UCL Astrophysics Group


Latest Group Publications

Our large and diverse group are busy in a wide array of research. Please scroll down to see the latest publications.


Cross-sections for heavy atmospheres: H2O self-broadening

The discovery of super-Earth and mini-Neptune exoplanets means that atmospheric signals from low-mass, temperate exoplanets are being increasingly studied. The signal acquired as the planet transits its host star, known as the transit depth, is smaller for these planets and, as such, more difficult to analyze. The launch of the space telescopes James Webb (JWST) & Ariel will give rise to an explosion in the quality and quantity of spectroscopic data available for an unprecedented number of exoplanets in our galaxy. []

June 2022: Anisman, Lara O., Chubb, Katy L., Changeat, Quentin, Edwards, Billy, Yurchenko, Sergei N., et al (Journal of Quantitative Spectroscopy and Radiative Transfer)

Non-local thermal equilibrium spectra of atmospheric molecules for exoplanets

Here we present a study of non-local thermodynamic equilibrium (LTE) effects on the exoplanetary spectra of a collection of molecules that are key in the investigation of exoplanet atmospheres: water, methane, carbon monoxide, and titanium oxide. These molecules are chosen as examples of different spectral ranges (infrared and ultraviolet), molecular types (diatomics and polyatomics), and spectral types (electronic and rovibrational); the importance of different vibrational bands in forming distinct non-LTE spectral features is investigated. Most notably, such key spectral signatures for distinguishing between the LTE and non-LTE cases include: for CH4 the 3.15 $\mu$m band region; for H2O the 2.0 and 2.7 $\mu$m band regions; for TiO, a strong variation in intensity in the bands between 0.5 and 0.75 $\mu$m; and a sole CO signature between 5 and 6 $\mu$m. []

May 2022: Wright, Sam O. M., Waldmann, Ingo, Yurchenko, Sergei N. (Monthly Notices of the Royal Astronomical Society)

Deep learning methods for obtaining photometric redshift estimations from images

Knowing the redshift of galaxies is one of the first requirements of many cosmological experiments, and as it is impossible to perform spectroscopy for every galaxy being observed, photometric redshift (photo-z) estimations are still of particular interest. Here, we investigate different deep learning methods for obtaining photo-z estimates directly from images, comparing these with 'traditional' machine learning algorithms which make use of magnitudes retrieved through photometry. As well as testing a convolutional neural network (CNN) and inception-module CNN, we introduce a novel mixed-input model that allows for both images and magnitude data to be used in the same model as a way of further improving the estimated redshifts. []

May 2022: Henghes, Ben, Thiyagalingam, Jeyan, Pettitt, Connor, Hey, Tony, Lahav, Ofer (Monthly Notices of the Royal Astronomical Society)

COSMOPOWER: emulating cosmological power spectra for accelerated Bayesian inference from next-generation surveys

We present COSMOPOWER, a suite of neural cosmological power spectrum emulators providing orders-of-magnitude acceleration for parameter estimation from two-point statistics analyses of Large-Scale Structure (LSS) and Cosmic Microwave Background (CMB) surveys. The emulators replace the computation of matter and CMB power spectra from Boltzmann codes; thus, they do not need to be re-trained for different choices of astrophysical nuisance parameters or redshift distributions. The matter power spectrum emulation error is less than $0.4{{\ \rm per\ cent}}$ in the wavenumber range $k \in [10^{-5}, 10] \, \mathrm{Mpc}^{-1}$ for redshift z ∈ [0, 5]. []

April 2022: Spurio Mancini, Alessio, Piras, Davide, Alsing, Justin, Joachimi, Benjamin, Hobson, Michael P. (Monthly Notices of the Royal Astronomical Society)

ExoMol line lists - XLV. Rovibronic molecular line lists of calcium monohydride (CaH) and magnesium monohydride (MgH)

New molecular line lists for calcium monohydride (40Ca1H) and magnesium monohydride (24Mg1H) and its minor isotopologues (25Mg1H and 26Mg1H) are presented. The rotation-vibration-electronic (rovibronic) line lists, named XAB, consider transitions involving the $X\, {}^{2}\Sigma ^{+}$, $A\, {}^{2}\Pi$, and $B/B^{\prime }\, {}^{2}\Sigma ^{+}$ electronic states in the 0-30 000 cm-1 region (wavelengths λ > 0.33 μm) and are suitable for temperatures up to 5000 K. A comprehensive analysis of the published spectroscopic literature on CaH and MgH is used to obtain new extensive data sets of accurate rovibronic energy levels with measurement uncertainties and consistent quantum number labelling. []

April 2022: Owens, Alec, Dooley, Sophie, McLaughlin, Luke, Tan, Brandon, Zhang, Guanming, et al (Monthly Notices of the Royal Astronomical Society)

ExoMol molecular line lists - XLIII. Rovibronic transitions corresponding to the close-lying X 2Π and A 2Σ+ states of NaO

The sodium monoxide radical (NaO) is observed in night-glow in the Earth's mesosphere and likely has astronomical importance. This study concerns the optical transitions within the ground X 2Π state and to the very low-lying (Te ≍ 2000 cm-1) excited A 2Σ+ state. A line list consisting of rovibronic term values, allowed electric dipole transitions, Einstein coefficients, and partition functions for varying temperature are produced using a variational solution of the coupled-channel Schrödinger equations using the program DUO. []

April 2022: Mitev, G. B., Taylor, S., Tennyson, Jonathan, Yurchenko, S. N., Buchachenko, A. A., et al (Monthly Notices of the Royal Astronomical Society)

Explaining deep learning of galaxy morphology with saliency mapping

We successfully demonstrate the use of explainable artificial intelligence (XAI) techniques on astronomical data sets in the context of measuring galactic bar lengths. The method consists of training convolutional neural networks on human classified data from Galaxy Zoo in order to predict general galaxy morphologies, and then using SMOOTHGRAD (a saliency mapping technique) to extract the bar for measurement by a bespoke algorithm. We contrast this to another method of using a convolutional neural network to directly predict galaxy bar lengths. []

April 2022: Bhambra, Prabh, Joachimi, Benjamin, Lahav, Ofer (Monthly Notices of the Royal Astronomical Society)

Relentless and complex transits from a planetesimal debris disc

This article reports quasi-continuous transiting events towards WD 1054-226 at d = 36.2 pc and V = 16.0 mag, based on simultaneous, high-cadence, multiwavelength imaging photometry using ULTRACAM over 18 nights from 2019 to 2020 March. The predominant period is 25.02 h and corresponds to a circular orbit with blackbody Teq = 323 K, where a planetary surface can nominally support liquid water. The light curves reveal remarkable night-to-night similarity, with changes on longer time-scales, and lack any transit-free segments of unocculted starlight. []

April 2022: Farihi, J., Hermes, J. J., Marsh, T. R., Mustill, A. J., Wyatt, M. C., et al (Monthly Notices of the Royal Astronomical Society)

Infrared scaling for a graviton condensate

The coupling between gravity and matter provides an intriguing length scale in the infrared for theories of gravity within Einstein-Hilbert action and beyond. In particular, we will show that such an infrared length scale is determined by the number of gravitons Ng ≫ 1 associated to a given mass in the non-relativistic limit. After tracing out the matter degrees of freedom, the graviton vacuum is found to be in a displaced vacuum with an occupation number of gravitons Ng ≫ 1. []

April 2022: Bose, Sougato, Mazumdar, Anupam, Toroš, Marko (Nuclear Physics B)

On-sky validation of image-based adaptive optics wavefront sensor referencing

Context. Differentiating between a true exoplanet signal and residual speckle noise is a key challenge in high-contrast imaging (HCI). Speckles result from a combination of fast, slow, and static wavefront aberrations introduced by atmospheric turbulence and instrument optics. []

March 2022: Skaf, Nour, Guyon, Olivier, Gendron, Éric, Ahn, Kyohoon, Bertrou-Cantou, Arielle, et al (Astronomy and Astrophysics)

3D Line Radiative Transfer & Synthetic Observations with Magritte


March 2022: De Ceuster, Frederik, Ceulemans, Thomas, Srivastava, Atulit, Homan, Ward, Bolte, Jan, et al (The Journal of Open Source Software)

On Spectroscopic Phase-curve Retrievals: H2 Dissociation and Thermal Inversion in the Atmosphere of the Ultrahot Jupiter WASP-103 b

This work presents a reanalysis of the spectroscopic phase-curve observations of the ultrahot Jupiter WASP-103 b obtained by the Hubble Space Telescope (HST) and the Spitzer Telescope. Traditional 1D and unified 1.5D spectral retrieval techniques are employed, allowing to map the thermal structure and the abundances of trace gases in this planet as a function of longitude. On the dayside, the atmosphere is found to have a strong thermal inversion, with indications of thermal dissociation traced by continuum H- opacity. []

March 2022: Changeat, Quentin (The Astronomical Journal)

GOLDRUSH. IV. Luminosity Functions and Clustering Revealed with 4,000,000 Galaxies at z 2-7: Galaxy-AGN Transition, Star Formation Efficiency, and Implication for Evolution at z > 10

We present new measurements of rest-UV luminosity functions and angular correlation functions from 4,100,221 galaxies at z ~ 2-7 identified in the Subaru/Hyper Suprime-Cam survey and CFHT Large Area U-band Survey. The obtained luminosity functions at z ~ 4-7 cover a very wide UV luminosity range of ~ $0.002\mbox{--}2000{L}_{\mathrm{UV}}^{* }$ combined with previous studies, confirming that the dropout luminosity function is a superposition of the active galactic nucleus (AGN) luminosity function dominant at M UV ≲ -24 mag and the galaxy luminosity function dominant at M UV ≳ -22 mag, consistent with galaxy fractions based on 1037 spectroscopically identified sources. Galaxy luminosity functions estimated from the spectroscopic galaxy fractions show the bright-end excess beyond the Schechter function at ≳2σ levels, possibly made by inefficient mass quenching, low dust obscuration, and/or hidden AGN activity. []

March 2022: Harikane, Yuichi, Ono, Yoshiaki, Ouchi, Masami, Liu, Chengze, Sawicki, Marcin, et al (The Astrophysical Journal Supplement Series)

No strong dependence of Lyman continuum leakage on physical properties of star-forming galaxies at ≲ z ≲ 3.5

We present Lyman continuum (LyC) radiation escape fraction (fesc) measurements for 183 spectroscopically confirmed star-forming galaxies in the redshift range 3.11 < z < 3.53 in the Chandra Deep Field South. We use ground-based imaging to measure fesc, and use ground- and space-based photometry to derive galaxy physical properties using spectral energy distribution (SED) fitting. We additionally derive [O III] + H β equivalent widths (that fall in the observed K band) by including nebular emission in SED fitting. []

March 2022: Saxena, A., Pentericci, L., Ellis, R. S., Guaita, L., Calabrò, A., et al (Monthly Notices of the Royal Astronomical Society)

Forecasting the potential of weak lensing magnification to enhance LSST large-scale structure analyses

Recent works have shown that weak lensing magnification must be included in upcoming large-scale structure analyses, such as for the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), to avoid biasing the cosmological results. In this work we investigate whether including magnification has a positive impact on the precision of the cosmological constraints, as well as being necessary to avoid bias. []

March 2022: Mahony, Constance, Fortuna, Maria Cristina, Joachimi, Benjamin, Korn, Andreas, Hoekstra, Henk, et al (Monthly Notices of the Royal Astronomical Society)

Single frequency CMB B-mode inference with realistic foregrounds from a single training image

With a single training image and using wavelet phase harmonic augmentation, we present polarized Cosmic Microwave Background (CMB) foreground marginalization in a high-dimensional likelihood-free (Bayesian) framework. We demonstrate robust foreground removal using only a single frequency of simulated data for a BICEP-like sky patch. Using Moment Networks, we estimate the pixel-level posterior probability for the underlying {E, B} signal and validate the statistical model with a quantile-type test using the estimated marginal posterior moments. []

February 2022: Jeffrey, Niall, Boulanger, François, Wandelt, Benjamin D., Regaldo-Saint Blancard, Bruno, Allys, Erwan, et al (Monthly Notices of the Royal Astronomical Society)

Considerations for Optimizing the Photometric Classification of Supernovae from the Rubin Observatory

The Vera C. Rubin Observatory will increase the number of observed supernovae (SNe) by an order of magnitude; however, it is impossible to spectroscopically confirm the class for all SNe discovered. Thus, photometric classification is crucial, but its accuracy depends on the not-yet-finalized observing strategy of Rubin Observatory's Legacy Survey of Space and Time (LSST). []

February 2022: Alves, Catarina S., Peiris, Hiranya V., Lochner, Michelle, McEwen, Jason D., Allam, Tarek, et al (The Astrophysical Journal Supplement Series)

Measuring Chemical Likeness of Stars with Relevant Scaled Component Analysis

Identification of chemically similar stars using elemental abundances is core to many pursuits within Galactic archeology. However, measuring the chemical likeness of stars using abundances directly is limited by systematic imprints of imperfect synthetic spectra in abundance derivation. We present a novel data-driven model that is capable of identifying chemically similar stars from spectra alone. []

February 2022: de Mijolla, Damien, Ness, Melissa K. (The Astrophysical Journal)

History-independent tracers. Forgetful molecular probes of the physical conditions of the dense interstellar medium

Context. Molecular line emission is a powerful probe of the physical conditions of astrophysical objects but can be complex to model, and it is often unclear which transitions would be the best targets for observers who wish to constrain a given parameter.
Aims: We produce a list of molecular species for which the gas history can be ignored, removing a major modelling complexity. []

February 2022: Holdship, J., Viti, S. (Astronomy and Astrophysics)

ExoMol line lists - XLIV. Infrared and ultraviolet line list for silicon monoxide (28Si16O)

A new silicon monoxide (28Si16O) line list covering infrared, visible, and ultraviolet regions called SiOUVenIR is presented. This line list extends the infrared EBJT ExoMol line list by including vibronic transitions to the $A\, {}^{1}\Pi$ and $E\, {}^{1}\Sigma ^{+}$ electronic states. Strong perturbations to the $A\, {}^{1}\Pi$ band system are accurately modelled through the treatment of six dark electronic states: $C\, {}^{1}\Sigma ^{-}$, $D\, {}^{1}\Delta$, $a\, {}^{3}\Sigma ^{+}$, $b\, {}^{3}\Pi$, $e\, {}^{3}\Sigma ^{-}$, and $d\, {}^{3}\Delta$. []

February 2022: Yurchenko, Sergei N., Tennyson, Jonathan, Syme, Anna-Maree, Adam, Ahmad Y., Clark, Victoria H. J., et al (Monthly Notices of the Royal Astronomical Society)

Cross-sections for heavy atmospheres: H2O continuum

Most of the exoplanets detected up to now transit in front of their host stars, allowing for the generation of transmission spectra; the study of exoplanet atmospheres relies heavily upon accurate analysis of these spectra. Recent discoveries mean that the study of atmospheric signals from low-mass, temperate worlds are becoming increasingly common. The observed transit depth in these planets is small and more difficult to analyze. []

February 2022: Anisman, Lara O., Chubb, Katy L., Elsey, Jonathan, Al-Refaie, Ahmed, Changeat, Quentin, et al (Journal of Quantitative Spectroscopy and Radiative Transfer)

Sewing spacetime with Lorentzian threads: complexity and the emergence of time in quantum gravity

Holographic entanglement entropy was recently recast in terms of Riemannian flows or `bit threads'. We consider the Lorentzian analog to reformulate the `complexity=volume' conjecture using Lorentzian flows — timelike vector fields whose minimum flux through a boundary subregion is equal to the volume of the homologous maximal bulk Cauchy slice. By the nesting of Lorentzian flows, holographic complexity is shown to obey a number of properties. []

February 2022: Pedraza, Juan F., Russo, Andrea, Svesko, Andrew, Weller-Davies, Zachary (Journal of High Energy Physics)

White dwarfs identified in LAMOST Data Release 5

In this paper, we report white dwarfs (WD) identified in the 5th Data Release of the Large Area Multi-Object fibre Spectroscopic Telescope (LAMOST), including spectral types of DA, DB, DC, DZ, and so on. There are 2625 DA spectra of 2281 DA stars, 182 DB spectra of 166 DB stars, 62 DC spectra of 58 DC stars, 36 DZ spectra of 33 DZ stars, and many other types identified, in addition to our previous paper (Data Release 2). Amongst those sources, 393 DA stars and 46 DB stars are new identifications after cross-matching with the literature. []

January 2022: Guo, Jincheng, Zhao, Jingkun, Zhang, Huawei, Zhang, Jiajun, Bai, Yu, et al (Monthly Notices of the Royal Astronomical Society)

Biosignatures Associated with Organic Matter in Late Paleoproterozoic Stromatolitic Dolomite and Implications for Martian Carbonates

The documentation of biosignatures in Precambrian rocks is an important requirement in the search for evidence of life on other ancient planetary surfaces. Three major kinds of biosignatures are crucially important: primary microbial sedimentary textures, diagenetic organomineral assemblages, and stable isotope compositions. This study presents new petrographic, mineralogical, and organic geochemical analyses of biosignatures in dolomitic stromatolites from the Pethei Group (N.W.T., Canada) and the Kasegalik Formation of the Belcher Group (Nunavut, Canada). []

January 2022: Goodwin, Arthur, Papineau, Dominic (Astrobiology)

Supernova induced processing of interstellar dust: impact of interstellar medium gas density and gas turbulence

Quantifying the efficiency of dust destruction in the interstellar medium (ISM) due to supernovae (SNe) is crucial for the understanding of galactic dust evolution. We present 3D hydrodynamic simulations of an SN blast wave propagating through the ISM. The interaction between the forward shock of the remnant and the surrounding ISM leads to destruction of ISM dust by the shock-heated gas. []

January 2022: Kirchschlager, Florian, Mattsson, Lars, Gent, Frederick A. (Monthly Notices of the Royal Astronomical Society)

Spectroscopy of an extreme [O III] emitting active galactic nucleus at z = 3.212: implications for the reionization era

Reionization-era galaxies often display intense nebular emission lines, both in rest-frame optical ([O III] + H β) and ultraviolet (UV; C III], C IV). How such strong nebular emission is powered remains unclear, with both active galactic nuclei (AGNs) and hot stars considered equally viable. The UV continuum slopes of these early systems tend to be very blue (β < -2), reflecting minimal dust obscuration, young ages, and low metallicities. []

January 2022: Tang, Mengtao, Stark, Daniel P., Ellis, Richard S., Charlot, Stéphane, Feltre, Anna, et al (Monthly Notices of the Royal Astronomical Society)

Observational Limits on the Early-time Dust Mass in SN 1987A

In recent years, dust masses of a few tenths of a solar mass have been found in the expanding ejecta of a number of core-collapse supernovae. How dust forms in such quantities remains poorly understood; theories of dust formation predict lower total masses and much faster formation rates than observations imply. One suggestion to reconcile observations and theory was made by Dwek et al., who proposed that the dust forms very rapidly, and because of its optical depth, is not initially observationally detectable, only being gradually revealed as the ejecta expand. []

December 2021: Wesson, Roger, Bevan, Antonia (The Astrophysical Journal)

A high-resolution line list for AlO

Indications of aluminium monoxide in atmospheres of exoplanets are being reported. Studies using high-resolution spectroscopy should allow a strong detection but require high-accuracy laboratory data. A MARVEL (measured active rotational-vibrational energy levels) analysis is performed for the available spectroscopic data on 27Al16O: 22 473 validated transitions are used to determine 6485 distinct energy levels. []

December 2021: Bowesman, Charles A., Shuai, Meiyin, Yurchenko, Sergei N., Tennyson, Jonathan (Monthly Notices of the Royal Astronomical Society)

Semi-classical thermodynamics of quantum extremal surfaces in Jackiw-Teitelboim gravity

Quantum extremal surfaces (QES), codimension-2 spacelike regions which extremize the generalized entropy of a gravity-matter system, play a key role in the study of the black hole information problem. The thermodynamics of QESs, however, has been largely unexplored, as a proper interpretation requires a detailed understanding of backreaction due to quantum fields. We investigate this problem in semi-classical Jackiw-Teitelboim (JT) gravity, where the spacetime is the eternal two-dimensional Anti-de Sitter (AdS2) black hole, Hawking radiation is described by a conformal field theory with central charge c, and backreaction effects may be analyzed exactly. []

December 2021: Pedraza, Juan F., Svesko, Andrew, Sybesma, Watse, Visser, Manus R. (Journal of High Energy Physics)

Proper motions of OB stars in the far Carina Arm

In large-scale maps of the Galactic disc, the Carina Arm stands out as a clear spiral feature, hosting prominent star clusters and associations rich in massive stars. We study the proper motions of 4199 O and early B most likely in the far Carina Arm, at distances mainly in excess of 4 kpc from the Sun, within the sky region, 282° < ℓ < 294° and -3° < b < +1° (Galactic coordinates). The sample is constructed by extending an existing blue-selected catalogue, and cross-matching with Gaia EDR3 astrometry. []

December 2021: Drew, J. E., Monguió, M., Wright, N. J. (Monthly Notices of the Royal Astronomical Society)

The vibrational properties of benzene on an ordered water ice surface

We present a hybrid CCSD(T) + PBE-D3 approach to calculating the vibrational signatures for gas-phase benzene and benzene adsorbed on an ordered water ice surface. We compare the results of our method against experimentally recorded spectra and calculations performed using PBE-D3-only approaches (harmonic and anharmonic). Calculations use a proton ordered XIh water ice surface consisting of 288 water molecules, and results are compared against experimental spectra recorded for an ASW ice surface. []

December 2021: Clark, Victoria H. J., Benoit, David M. (Monthly Notices of the Royal Astronomical Society)

Outflows from starburst galaxies with various driving mechanisms and their X-ray properties

Outflows in starburst galaxies driven by thermal-mechanical energy, cosmic rays, and their mix are investigated with 1D and 2D hydrodynamic simulations. We show that these outflows could reach a stationary state, after which their hydrodynamic profiles asymptotically approach previous results obtained semi-analytically for stationary outflow configurations. The X-rays from the simulated outflows are computed, and high-resolution synthetic spectra and broad-band light curves are constructed. []

December 2021: Yu, B. P. Brian, Owen, Ellis R., Pan, Kuo-Chuan, Wu, Kinwah, Ferreras, Ignacio (Monthly Notices of the Royal Astronomical Society)

Lorentzian Threads as Gatelines and Holographic Complexity

The continuous min flow-max cut principle is used to reformulate the "complexity=volume " conjecture using Lorentzian flows—divergenceless norm-bounded timelike vector fields whose minimum flux through a boundary subregion is equal to the volume of the homologous maximal bulk Cauchy slice. The nesting property is used to show the rate of complexity is bounded below by "conditional complexity," describing a multistep optimization with intermediate and final target states. Conceptually, discretized Lorentzian flows are interpreted in terms of threads or gatelines such that complexity is equal to the minimum number of gatelines used to prepare a conformal field theory (CFT) state by an optimal tensor network (TN) discretizing the state. []

December 2021: Pedraza, Juan F., Russo, Andrea, Svesko, Andrew, Weller-Davies, Zachary (Physical Review Letters)

A buyer's guide to the Hubble constant

Since the expansion of the universe was first established by Edwin Hubble and Georges Lemaître about a century ago, the Hubble constant H0 which measures its rate has been of great interest to astronomers. Besides being interesting in its own right, few properties of the universe can be deduced without it. In the last decade, a significant gap has emerged between different methods of measuring it, some anchored in the nearby universe, others at cosmological distances. []

December 2021: Shah, Paul, Lemos, Pablo, Lahav, Ofer (Astronomy and Astrophysics Review)

The causal effect of environment on halo mass and concentration

Understanding the impact of environment on the formation and evolution of dark matter haloes and galaxies is a crucial open problem. Studying statistical correlations in large simulated populations sheds some light on these impacts, but the causal effect of an environment on individual objects is harder to pinpoint. Addressing this, we present a new method for resimulating a single dark matter halo in multiple large-scale environments. []

November 2021: Cadiou, Corentin, Pontzen, Andrew, Peiris, Hiranya V., Lucie-Smith, Luisa (Monthly Notices of the Royal Astronomical Society)

Geometry versus growth. Internal consistency of the flat ΛCDM model with KiDS-1000

We carry out a multi-probe self-consistency test of the flat Lambda Cold Dark Matter (ΛCDM) model with the aim of exploring potential causes of the reported tensions between high- and low-redshift cosmological observations. We divide the model into two theory regimes determined by the smooth background (geometry) and the evolution of matter density fluctuations (growth), each governed by an independent set of ΛCDM cosmological parameters. This extended model is constrained by a combination of weak gravitational lensing measurements from the Kilo-Degree Survey, galaxy clustering signatures extracted from Sloan Digital Sky Survey campaigns and the Six-Degree Field Galaxy Survey, and the angular baryon acoustic scale and the primordial scalar fluctuation power spectrum measured in Planck cosmic microwave background (CMB) data. []

November 2021: Ruiz-Zapatero, Jaime, Stölzner, Benjamin, Joachimi, Benjamin, Asgari, Marika, Bilicki, Maciej, et al (Astronomy and Astrophysics)

Peeking inside the Black Box: Interpreting Deep-learning Models for Exoplanet Atmospheric Retrievals

Deep-learning algorithms are growing in popularity in the field of exoplanetary science due to their ability to model highly nonlinear relations and solve interesting problems in a data-driven manner. Several works have attempted to perform fast retrievals of atmospheric parameters with the use of machine-learning algorithms like deep neural networks (DNNs). Yet, despite their high predictive power, DNNs are also infamous for being "black boxes." It is their apparent lack of explainability that makes the astrophysics community reluctant to adopt them. []

November 2021: Yip, Kai Hou, Changeat, Quentin, Nikolaou, Nikolaos, Morvan, Mario, Edwards, Billy, et al (The Astronomical Journal)

Quantifying the rarity of the local super-volume

We investigate the extent to which the number of clusters of mass exceeding $10^{15}\, M_{\odot }\, h^{-1}$ within the local super-volume ($\lt 135\mathrm{\, Mpc\, }h^{-1}$) is compatible with the standard ΛCDM cosmological model. Depending on the mass estimator used, we find that the observed number N of such massive structures can vary between 0 and 5. Adopting N = 5 yields ΛCDM likelihoods as low as 2.4 × 10-3 (with σ8 = 0.81) or 3.8 × 10-5 (with σ8 = 0.74). []

November 2021: Stopyra, Stephen, Peiris, Hiranya V., Pontzen, Andrew, Jasche, Jens, Natarajan, Priyamvada (Monthly Notices of the Royal Astronomical Society)

Qudits for witnessing quantum-gravity-induced entanglement of masses under decoherence

Recently, a theoretical and an experimental protocol known as quantum-gravity-induced entanglement of masses (QGEM) has been proposed to test the quantum nature of gravity using two mesoscopic masses, each placed in a superposition of two locations. If after eliminating all nongravitational interactions between them the particles become entangled, one can conclude that the gravitational potential is induced via a quantum mediator, i.e., graviton. In this paper we explore extensions of the QGEM experiment to multidimensional quantum objects and examine a range of different experiment geometries, in order to determine which would generate entanglement faster. []

November 2021: Tilly, Jules, Marshman, Ryan J., Mazumdar, Anupam, Bose, Sougato (Physical Review A)

Large-scale clustering amongst Fermi blazars; evidence for axis alignments?

We find evidence for large-scale clustering amongst Fermi-selected BL Lac objects but not amongst Fermi-selected flat spectrum radio quasars (FSRQs). Using two-point correlation functions, we have investigated the clustering properties of different classes of objects from the Fermi-LAT(Large Area Telescope) 4FGL catalogue. We wanted to test the idea based on optical polarization observations that there might be large volumes of space in which AGN axes are aligned. []

October 2021: Marchã, M. J. M., Browne, I. W. A. (Monthly Notices of the Royal Astronomical Society)

The distribution and origin of C2H in NGC 253 from ALCHEMI

Context. Observations of chemical species can provide insights into the physical conditions of the emitting gas however it is important to understand how their abundances and excitation vary within different heating environments. C2H is a molecule typically found in PDR regions of our own Galaxy but there is evidence to suggest it also traces other regions undergoing energetic processing in extragalactic environments. []

October 2021: Holdship, J., Viti, S., Martín, S., Harada, N., Mangum, J., et al (Astronomy and Astrophysics)

Carbon-enhanced stars with short orbital and spin periods

Many characteristics of dwarf carbon stars are broadly consistent with a binary origin, including mass transfer from an evolved companion. While the population overall appears to have old-disc or halo kinematics, roughly 2 per cent of these stars exhibit Hα emission, which in low-mass main-sequence stars is generally associated with rotation and relative youth. Its presence in an older population therefore suggests either irradiation or spin-up. []

October 2021: Whitehouse, L. J., Farihi, J., Howarth, I. D., Mancino, S., Walters, N., et al (Monthly Notices of the Royal Astronomical Society)

Unbiased likelihood-free inference of the Hubble constant from light standard sirens

Multimessenger observations of binary neutron star mergers offer a promising path toward resolution of the Hubble constant (H0) tension, provided their constraints are shown to be free from systematics such as the Malmquist bias. In the traditional Bayesian framework, accounting for selection effects in the likelihood requires calculation of the expected number (or fraction) of detections as a function of the parameters describing the population and cosmology; a potentially costly and/or inaccurate process. This calculation can, however, be bypassed completely by performing the inference in a framework in which the likelihood is never explicitly calculated, but instead fit using forward simulations of the data, which naturally include the selection. []

October 2021: Gerardi, Francesca, Feeney, Stephen M., Alsing, Justin (Physical Review D)

SUPER. V. ALMA continuum observations of z ∼ 2 AGN and the elusive evidence of outflows influencing star formation

We study the impact of active galactic nuclei (AGN) ionised outflows on star formation in high-redshift AGN host galaxies, by combining near-infrared integral field spectroscopic (IFS) observations, mapping the Hα emission and [O III]λ5007 outflows, with matched-resolution observations of the rest-frame far-infrared (FIR) emission. We present high-resolution ALMA Band 7 observations of eight X-ray selected AGN (L2 − 10 keV = 1043.8 − 1045.2 erg s−1) at z ∼ 2 from the SUPER (SINFONI Survey for Unveiling the Physics and Effect of Radiative feedback) sample, targeting the observed-frame 870 μm (rest-frame ∼260 μm) continuum at ∼2 kpc (0.2″) spatial resolution. The targets were selected among the SUPER AGN with an [O III] detection in the IFS maps and with a detection in the FIR photometry. []

October 2021: Lamperti, I., Harrison, C. M., Mainieri, V., Kakkad, D., Perna, M., et al (Astronomy and Astrophysics)

Cosmology beyond BAO from the 3D distribution of the Lyman-α forest

We propose a new method for fitting the full-shape of the Lyman-α (Ly α) forest 3D correlation function in order to measure the Alcock-Paczynski (AP) effect. Our method preserves the robustness of baryon acoustic oscillations (BAO) analyses, while also providing extra cosmological information from a broader range of scales. We compute idealized forecasts for the Dark Energy Spectroscopic Instrument (DESI) using the Ly α autocorrelation and its cross-correlation with quasars, and show how this type of analysis improves cosmological constraints. []

October 2021: Cuceu, Andrei, Font-Ribera, Andreu, Joachimi, Benjamin, Nadathur, Seshadri (Monthly Notices of the Royal Astronomical Society)

Evidence for sub-Chandrasekhar Type Ia supernovae from the last major merger

We investigate the contribution of sub-Chandrasekhar mass Type Ia supernovae to the chemical enrichment of the Gaia Sausage galaxy, the progenitor of a significant merger event in the early life of the Milky Way. Using a combination of data from Nissen & Schuster, the GALactic Archaeology with HERMES (GALAH) Data Release 3 [with 1D non-local thermal equilibrium (NLTE) abundance corrections], and the Apache Point Observatory Galactic Evolution Experiment (APOGEE) Data Release 16, we fit analytic chemical evolution models to a nine-dimensional chemical abundance space (Fe, Mg, Si, Ca, Cr, Mn, Ni, Cu, and Zn) in particular focusing on the iron-peak elements, Mn and Ni. We find that low [Mn/Fe] $\sim -0.15\, \mathrm{dex}$ and low [Ni/Fe] $\sim -0.3\, \mathrm{dex}$ Type Ia yields are required to explain the observed trends beyond the [α/Fe] knee of the Gaia Sausage (approximately at [Fe/H] $=-1.4\, \mathrm{dex}$). []

September 2021: Sanders, Jason L., Belokurov, Vasily, Man, Kai T. F. (Monthly Notices of the Royal Astronomical Society)

Disentangling atmospheric compositions of K2-18 b with next generation facilities

Recent analysis of the planet K2-18 b has shown the presence of water vapour in its atmosphere. While the H2O detection is significant, the Hubble Space Telescope (HST) WFC3 spectrum suggests three possible solutions of very different nature which can equally match the data. The three solutions are a primary cloudy atmosphere with traces of water vapour (cloudy sub-Neptune), a secondary atmosphere with a substantial amount (up to 50% Volume Mixing Ratio) of H2O (icy/water world) and/or an undetectable gas such as N2 (super-Earth). []

September 2021: Changeat, Quentin, Edwards, Billy, Al-Refaie, Ahmed F., Tsiaras, Angelos, Waldmann, Ingo P., et al (Experimental Astronomy)

Full-sky integrated Sachs-Wolfe maps for the MICE grand challenge lightcone simulation

We present full-sky maps of the Integrated Sachs-Wolfe effect (ISW) for the MICE Grand Challenge lightcone simulation up to redshift 1.4. The maps are constructed in the linear regime using spherical Bessel transforms. We compare and contrast this procedure against analytical approximations found in the literature. []

September 2021: Naidoo, Krishna, Fosalba, Pablo, Whiteway, Lorne, Lahav, Ofer (Monthly Notices of the Royal Astronomical Society)

Chemulator: Fast, accurate thermochemistry for dynamical models through emulation

Context. Chemical modelling serves two purposes in dynamical models: accounting for the effect of microphysics on the dynamics and providing observable signatures. Ideally, the former must be done as part of the hydrodynamic simulation but this comes with a prohibitive computational cost that leads to many simplifications being used in practice. []

September 2021: Holdship, J., Viti, S., Haworth, T. J., Ilee, J. D. (Astronomy and Astrophysics)

Collisions in a gas-rich white dwarf planetary debris disc

WD 0145+234 is a white dwarf that is accreting metals from a circumstellar disc of planetary material. It has exhibited a substantial and sustained increase in 3-5 $\mu$m flux since 2018. Follow-up Spitzer photometry reveals that emission from the disc had begun to decrease by late 2019. []

September 2021: Swan, Andrew, Kenyon, Scott J., Farihi, Jay, Dennihy, Erik, Gänsicke, Boris T., et al (Monthly Notices of the Royal Astronomical Society)

Gravitons in a box

Gravity and matter are universally coupled, and this unique universality provides us with an intriguing way to quantify quantum aspects of space-time in terms of the number of gravitons within a given box. In particular, we provide a limit on the number of gravitons if we trace out the matter degrees of freedom. We obtain the universal bound on the number of gravitons, which would be given by Ng≈(m /Mp)2. []

September 2021: Bose, Sougato, Mazumdar, Anupam, Toroš, Marko (Physical Review D)

Benchmarking and scalability of machine-learning methods for photometric redshift estimation

Obtaining accurate photometric redshift (photo-z) estimations is an important aspect of cosmology, remaining a prerequisite of many analyses. In creating novel methods to produce photo-z estimations, there has been a shift towards using machine-learning techniques. However, there has not been as much of a focus on how well different machine-learning methods scale or perform with the ever-increasing amounts of data being produced. []

August 2021: Henghes, Ben, Pettitt, Connor, Thiyagalingam, Jeyan, Hey, Tony, Lahav, Ofer (Monthly Notices of the Royal Astronomical Society)

The VANDELS Survey: new constraints on the high-mass X-ray binary populations in normal star-forming galaxies at 3 < z < 5.5

We use VANDELS spectroscopic data overlapping with the ≃7 Ms Chandra Deep Field South survey to extend studies of high-mass X-ray binary systems (HMXBs) in 301 normal star-forming galaxies in the redshift range 3 < z < 5.5. Our analysis evaluates correlations between X-ray luminosities (LX), star formation rates (SFRs), and stellar metallicities (Z) to higher redshifts and over a wider range in galaxy properties than hitherto. Using a stacking analysis performed in bins of both redshift and SFR for sources with robust spectroscopic redshifts without AGN signatures, we find convincing evolutionary trends in the ratio LX/SFR to the highest redshifts probed, with a stronger trend for galaxies with lower SFRs. []

August 2021: Saxena, A., Ellis, R. S., Förster, P. U., Calabrò, A., Pentericci, L., et al (Monthly Notices of the Royal Astronomical Society)

Dark Energy Survey Year 3 results: Curved-sky weak lensing mass map reconstruction

We present reconstructed convergence maps, mass maps, from the Dark Energy Survey (DES) third year (Y3) weak gravitational lensing data set. The mass maps are weighted projections of the density field (primarily dark matter) in the foreground of the observed galaxies. We use four reconstruction methods, each is a maximum a posteriori estimate with a different model for the prior probability of the map: Kaiser-Squires, null B-mode prior, Gaussian prior, and a sparsity prior. []

August 2021: Jeffrey, N., Gatti, M., Chang, C., Whiteway, L., Demirbozan, U., et al (Monthly Notices of the Royal Astronomical Society)

TauREx 3: A Fast, Dynamic, and Extendable Framework for Retrievals

TauREx 3 is the next generation of the TauREx exoplanet atmospheric retrieval framework for Windows, Mac, and Linux. It is a complete rewrite with a full Python stack that makes it easy-to-use, high-performance, dynamic, and flexible. The new main TauREx program is built with modularity in mind, allowing the user to augment its functionalities with custom code and efficiently perform retrievals on custom parameters. []

August 2021: Al-Refaie, A. F., Changeat, Q., Waldmann, I. P., Tinetti, G. (The Astrophysical Journal)

Assessing tension metrics with dark energy survey and Planck data

Quantifying tensions - inconsistencies amongst measurements of cosmological parameters by different experiments - has emerged as a crucial part of modern cosmological data analysis. Statistically significant tensions between two experiments or cosmological probes may indicate new physics extending beyond the standard cosmological model and need to be promptly identified. We apply several tension estimators proposed in the literature to the dark energy survey (DES) large-scale structure measurement and Planck cosmic microwave background data. []

August 2021: Lemos, P., Raveri, M., Campos, A., Park, Y., Chang, C., et al (Monthly Notices of the Royal Astronomical Society)

Revealing the Physical Conditions around Sgr A* Using Bayesian Inference. I. Observations and Radiative Transfer

We report subarcsecond Atacama Large Millimeter/submillimeter Array (ALMA) observations between 272 and 375 GHz toward Sgr A*'s circumnuclear disk (CND). Our data comprise eight individual pointings, with significant SiO (87-76) and SO (7-6) emission detected toward 98 positions within these pointings. Additionally, we identify H2CS (91,9-81,8), OCS (25-24), and CH3OH (21,1-20,2) toward a smaller subset of positions. []

August 2021: James, Tomas A., Viti, Serena, Yusef-Zadeh, Farhad, Royster, Marc, Wardle, Mark (The Astrophysical Journal)

ExoMol molecular line lists - XLII. Rovibronic molecular line list for the low-lying states of NO

An accurate line list, called XABC, is computed for nitric oxide which covers its pure rotational, vibrational and rovibronic spectra. A mixture of empirical and theoretical electronic transition dipole moments are used for the final calculation of 14N16O rovibronic $\mathrm{A}\, ^2\Sigma ^+$ - $\mathrm{X}\, ^2\Pi$, $\mathrm{B}\, ^2\Pi$ - X2Π, and $\mathrm{C}\, ^2\Pi$ - $\mathrm{X}\, ^2\Pi$ which correspond to the γ, β, and δ band systems, respectively, as well as minor improvements to transitions within the $\mathrm{X}\, ^2\Pi$ ground state. The work is a major update of the ExoMol NOname line list. []

July 2021: Qu, Qianwei, Yurchenko, Sergei N., Tennyson, Jonathan (Monthly Notices of the Royal Astronomical Society)

Constraints on the dust extinction law of the Galaxy with Swift/UVOT, Gaia, and 2MASS

We explore variations of the dust extinction law of the Milky Way by selecting stars from the Swift/UVOT Serendipitous Source Catalogue, cross-matched with Gaia DR2 and 2MASS to produce a sample of 10 452 stars out to ~4 kpc with photometry covering a wide spectral window. The near ultraviolet passbands optimally encompass the 2175 Å bump, so that we can simultaneously fit the net extinction, quoted in the V band (AV), the steepness of the wavelength dependence (δ), and the bump strength (Eb). The methodology compares the observed magnitudes with theoretical stellar atmospheres from the models of Coelho. []

July 2021: Ferreras, Ignacio, Tress, Mónica, Bruzual, Gustavo, Charlot, Stéphane, Page, Mat, et al (Monthly Notices of the Royal Astronomical Society)

Original Research by Young Twinkle Students (ORBYTS): ephemeris refinement of transiting exoplanets

We report follow-up observations of transiting exoplanets that have either large uncertainties (>10 min) in their transit times or have not been observed for over 3 yr. A fully robotic ground-based telescope network, observations from citizen astronomers, and data from TESS have been used to study eight planets, refining their ephemerides and orbital data. Such follow-up observations are key for ensuring accurate transit times for upcoming ground- and space-based telescopes, which may seek to characterize the atmospheres of these planets. []

July 2021: Edwards, Billy, Changeat, Quentin, Yip, Kai Hou, Tsiaras, Angelos, Taylor, Jake, et al (Monthly Notices of the Royal Astronomical Society)

The dust mass in Cassiopeia A from infrared and optical line flux differences

The large quantities of dust that have been found in a number of high-redshift galaxies have led to suggestions that core-collapse supernovae (CCSNe) are the main sources of their dust and have motivated the measurement of the dust masses formed by local CCSNe. For Cassiopeia A (Cas A), an oxygen-rich remnant of a Type IIb CCSN, a dust mass of 0.6-1.1 M has already been determined by two different methods, namely (a) from its far-infrared spectral energy distribution and (b) from analysis of the red-blue emission line asymmetries in its integrated optical spectrum. We present a third, independent, method for determining the mass of dust contained within Cas A. []

June 2021: Niculescu-Duvaz, Maria, Barlow, M. J., Bevan, A., Milisavljevic, D., De Looze, I. (Monthly Notices of the Royal Astronomical Society)

Magnification bias in galaxy surveys with complex sample selection functions

Gravitational lensing magnification modifies the observed spatial distribution of galaxies and can severely bias cosmological probes of large-scale structure if not accurately modelled. Standard approaches to modelling this magnification bias may not be applicable in practice as many galaxy samples have complex, often implicit, selection functions. We propose and test a procedure to quantify the magnification bias induced in clustering and galaxy-galaxy lensing (GGL) signals in galaxy samples subject to a selection function beyond a simple flux limit. []

June 2021: von Wietersheim-Kramsta, Maximilian, Joachimi, Benjamin, van den Busch, Jan Luca, Heymans, Catherine, Hildebrandt, Hendrik, et al (Monthly Notices of the Royal Astronomical Society)

Terminus: A Versatile Simulator for Space-based Telescopes

Space-based telescopes offer unparalleled opportunities for characterizing exoplanets, solar system bodies, and stellar objects. However, observatories in low-Earth orbits (e.g., Hubble, CHaracterising ExOPlanets Satellite, Twinkle, and an ever-increasing number of cubesats) cannot always be continuously pointed at a target due to Earth obscuration. For exoplanet observations consisting of transit, or eclipse, spectroscopy, this causes gaps in the light curve, which reduces the information content and can diminish the science return of the observation. []

June 2021: Edwards, Billy, Stotesbury, Ian (The Astronomical Journal)

Self-calibration and robust propagation of photometric redshift distribution uncertainties in weak gravitational lensing

We present a method that accurately propagates residual uncertainties in photometric redshift distributions into the cosmological inference from weak lensing measurements. The redshift distributions of tomographic redshift bins are parameterised using a flexible modified Gaussian mixture model. We fit this model to pre-calibrated redshift distributions and implement an analytic marginalisation over the potentially several hundred redshift nuisance parameters in the weak lensing likelihood, which is demonstrated to accurately recover the cosmological posterior. []

June 2021: Stölzner, B., Joachimi, B., Korn, A., Hildebrandt, H., Wright, A. H. (Astronomy and Astrophysics)

Chronos: A NIR spectroscopic galaxy survey to probe the most fundamental stages of galaxy evolution

We propose a dedicated, ultra-deep spectroscopic survey in the near infrared (NIR), that will target a mass-limited sample of galaxies during two of the most fundamental epochs of cosmic evolution: the formation of the first galaxies (at z ≳ 6; cosmic dawn), and at the peak of galaxy formation activity (at redshift z∼1-3; cosmic noon). By way of NIR observations (λ= 0.8-2μ m), it is possible to study the UV Lyman-α region in the former, and the optical rest-frame in the latter, allowing us to extract fundamental observables such as gas and stellar kinematics, chemical abundances, and ages, providing a unique legacy database covering these two crucial stages of cosmic evolution. The need to work in the NIR at extremely low flux levels makes a ground-based approach unfeasible due to atmospheric emission and absorption. []

June 2021: Ferreras, I., Cropper, M., Sharples, R., Bland-Hawthorn, J., Bruzual, G., et al (Experimental Astronomy)

A test of the planet-star unipolar inductor for magnetic white dwarfs

Despite thousands of spectroscopic detections, only four isolated white dwarfs exhibit Balmer emission lines. The temperature inversion mechanism is a puzzle over 30 years old that has defied conventional explanations. One hypothesis is a unipolar inductor that achieves surface heating via ohmic dissipation of a current loop between a conducting planet and a magnetic white dwarf. []

May 2021: Walters, N., Farihi, J., Marsh, T. R., Bagnulo, S., Landstreet, J. D., et al (Monthly Notices of the Royal Astronomical Society)

Fine structure of type III solar radio bursts from Langmuir wave motion in turbulent plasma

The Sun frequently accelerates near-relativistic electron beams that travel out through the solar corona and interplanetary space. Interacting with their plasma environment, these beams produce type III radio bursts—the brightest astrophysical radio sources seen from Earth. The formation and motion of type III fine frequency structures is a puzzle, but is commonly believed to be related to plasma turbulence in the solar corona and solar wind. []

May 2021: Reid, Hamish A. S., Kontar, Eduard P. (Nature Astronomy)

Electron Bulk Heating at Saturn's Magnetopause

Magnetic reconnection at the magnetopause (MP) energizes ambient plasma via the release of magnetic energy and produces an "open" magnetosphere allowing solar wind particles to directly enter the system. At Saturn, the nature of MP reconnection remains unclear. The current study examines electron bulk heating at MP crossings, in order to probe the relationship between observed and predicted reconnection heating proposed by Phan et al. []

May 2021: Cheng, I., Achilleos, N., Masters, A., Lewis, G., Kane, M., et al (Journal of Geophysical Research (Space Physics))

An emulator for the Lyman-α forest in beyond-ΛCDM cosmologies

Interpreting observations of the Lyman-α forest flux power spectrum requires interpolation between a small number of expensive simulations. We present a Gaussian process emulator modelling the 1D flux power spectrum as a function of the amplitude and slope of the small-scale linear matter power spectrum, and the state of the intergalactic medium at the epoch of interest (2 < z < 4). This parameterisation enables the prediction of the flux power spectrum in extended cosmological models that are not explicitly included in the training set, eliminating the need to construct bespoke emulators for a number of extensions to ΛCDM. []

May 2021: Pedersen, Christian, Font-Ribera, Andreu, Rogers, Keir K., McDonald, Patrick, Peiris, Hiranya V., et al (Journal of Cosmology and Astroparticle Physics)

The PAU Survey: narrow-band photometric redshifts using Gaussian processes

We study the performance of the hybrid template machine learning photometric redshift (photo-z) algorithm DELIGHT, which uses Gaussian processes, on a subset of the early data release of the Physics of the Accelerating Universe Survey (PAUS). We calibrate the fluxes of the 40 PAUS narrow bands with six broad-band fluxes (uBVriz) in the Cosmic Evolution Survey (COSMOS) field using three different methods, including a new method that utilizes the correlation between the apparent size and overall flux of the galaxy. We use a rich set of empirically derived galaxy spectral templates as guides to train the Gaussian process, and we show that our results are competitive with other standard photometric redshift algorithms. []

May 2021: Soo, John Y. H., Joachimi, Benjamin, Eriksen, Martin, Siudek, Małgorzata, Alarcon, Alex, et al (Monthly Notices of the Royal Astronomical Society)

Disentangled Representation Learning for Astronomical Chemical Tagging

Modern astronomical surveys are observing spectral data for millions of stars. These spectra contain chemical information that can be used to trace the Galaxy's formation and chemical enrichment history. However, extracting the information from spectra and making precise and accurate chemical abundance measurements is challenging. []

May 2021: de Mijolla, Damien, Ness, Melissa Kay, Viti, Serena, Wheeler, Adam Joseph (The Astrophysical Journal)

Self-calibration of weak lensing systematic effects using combined two- and three-point statistics

We investigate the prospects for using the weak lensing bispectrum alongside the power spectrum to control systematic uncertainties in a Euclid-like survey. Three systematic effects are considered: the intrinsic alignment of galaxies, uncertainties in the means of tomographic redshift distributions, and multiplicative bias in the measurement of the shear signal. We find that the bispectrum is very effective in mitigating these systematic errors. []

May 2021: Pyne, Susan, Joachimi, Benjamin (Monthly Notices of the Royal Astronomical Society)

An Exploration of Model Degeneracies with a Unified Phase Curve Retrieval Analysis: The Light and Dark Sides of WASP-43 b

The analysis of exoplanetary atmospheres often relies upon the observation of transit or eclipse events. While very powerful, these snapshots provide mainly one-dimensional information on the planet structure and do not easily allow precise latitude-longitude characterizations. The phase curve technique, which consists of measuring the planet emission throughout its entire orbit, can break this limitation and provide useful two-dimensional thermal and chemical constraints on the atmosphere. []

May 2021: Changeat, Q., Al-Refaie, A. F., Edwards, B., Waldmann, I. P., Tinetti, G. (The Astrophysical Journal)

An improved rovibrational linelist of formaldehyde, H212 C16O

Published high-resolution rotation-vibration transitions of H212C16O, the principal isotopologue of methanal, are analyzed using the MARVEL (Measured Active Rotation-Vibration Energy Levels) procedure. The literature results are augmented by new, high-accuracy measurements of pure rotational transitions within the ground, ν3 , ν4 , and ν6 vibrational states. Of the 16 596 non-redundant transitions processed, which come from 43 sources including the present work, 16 403 could be validated, providing 5029 empirical energy levels of H212C16O with statistically well-defined uncertainties. []

May 2021: Al-Derzi, Afaf R., Tennyson, Jonathan, Yurchenko, Sergei N., Melosso, Mattia, Jiang, Ningjing, et al (Journal of Quantitative Spectroscopy and Radiative Transfer)

Lyman-alpha spectroscopy of extreme [O III] emitting galaxies at z ≃ 2-3: implications for Lyα visibility and LyC leakage at z > 6

Spectroscopic observations of massive z > 7 galaxies selected to have extremely large [O III] + H β equivalent width (EW ~1500 Å) have recently revealed large Ly α detection rates, in contrast to the weak emission seen in the general population. Why these systems are uniquely visible in Ly α at redshifts where the intergalactic medium (IGM) is likely significantly neutral is not clear. With the goal of better understanding these results, we have begun a campaign with MMT and Magellan to measure Ly α in galaxies with similar [O III] + H β EWs at z ≃ 2-3. []

May 2021: Tang, Mengtao, Stark, Daniel P., Chevallard, Jacopo, Charlot, Stéphane, Endsley, Ryan, et al (Monthly Notices of the Royal Astronomical Society)

A comparison of quasar emission reconstruction techniques for z ≥ 5.0 Lyman α and Lyman β transmission

Reconstruction techniques for intrinsic quasar continua are crucial for the precision study of Lyman α (Ly α) and Lyman β (Ly β) transmission at z > 5.5, where the λ < 1215 Å emission of quasars is nearly completely absorbed. While the number and quality of spectroscopic observations have become theoretically sufficient to quantify Ly α transmission at 5.0 < z < 6.0 to better than $1{{\ \rm per\ cent}}$, the biases and uncertainties arising from predicting the unabsorbed continuum are not known to the same level. In this paper, we systematically evaluate eight reconstruction techniques on a unified testing sample of 2.7 < z < 3.5 quasars drawn from the Extended Baryon Oscillation Spectroscopic Survey. []

May 2021: Bosman, Sarah E. I., Ďurovčíková, Dominika, Davies, Frederick B., Eilers, Anna-Christina (Monthly Notices of the Royal Astronomical Society)

Organised randoms: Learning and correcting for systematic galaxy clustering patterns in KiDS using self-organising maps

We present a new method for the mitigation of observational systematic effects in angular galaxy clustering through the use of corrective random galaxy catalogues. Real and synthetic galaxy data from the Kilo Degree Survey's (KiDS) 4th Data Release (KiDS-1000) and the Full-sky Lognormal Astro-fields Simulation Kit package, respectively, are used to train self-organising maps to learn the multivariate relationships between observed galaxy number density and up to six systematic-tracer variables, including seeing, Galactic dust extinction, and Galactic stellar density. We then create `organised' randoms; random galaxy catalogues with spatially variable number densities, mimicking the learnt systematic density modes in the data. []

April 2021: Johnston, Harry, Wright, Angus H., Joachimi, Benjamin, Bilicki, Maciej, Elisa Chisari, Nora, et al (Astronomy and Astrophysics)

Erratum: Evaluating hydrodynamical simulations with green valley galaxies


April 2021: Angthopo, J., Negri, A., Ferreras, I., de la Rosa, I. G., Vecchia, C. Dalla, et al (Monthly Notices of the Royal Astronomical Society)

Angular momentum evolution can be predicted from cosmological initial conditions

The angular momentum of dark matter haloes controls their spin magnitude and orientation, which in turn influences the galaxies therein. However, the process by which dark matter haloes acquire angular momentum is not fully understood; in particular, it is unclear whether angular momentum growth is stochastic. To address this question, we extend the genetic modification technique to allow control over the angular momentum of any region in the initial conditions. []

April 2021: Cadiou, Corentin, Pontzen, Andrew, Peiris, Hiranya V. (Monthly Notices of the Royal Astronomical Society)

Prospects for Measuring the Hubble Constant with Neutron-Star-Black-Hole Mergers

Gravitational wave (GW) and electromagnetic (EM) observations of neutron-star-black-hole (NSBH) mergers can provide precise local measurements of the Hubble constant (H0), ideal for resolving the current H0 tension. We perform end-to-end analyses of realistic populations of simulated NSBHs, incorporating both GW and EM selection for the first time. We show that NSBHs could achieve unbiased 1.5%-2.4% precision H0 estimates by 2030. []

April 2021: Feeney, Stephen M., Peiris, Hiranya V., Nissanke, Samaya M., Mortlock, Daniel J. (Physical Review Letters)

Phase-curve Pollution of Exoplanet Transmission Spectra

The occurrence of a planet transiting in front of its host star offers the opportunity to observe the planet's atmosphere filtering starlight. The fraction of occulted stellar flux is roughly proportional to the optically thick area of the planet, the extent of which depends on the opacity of the planet's gaseous envelope at the observed wavelengths. Chemical species, haze, and clouds are now routinely detected in exoplanet atmospheres through rather small features in transmission spectra, i.e., collections of planet-to-star area ratios across multiple spectral bins and/or photometric bands. []

April 2021: Morello, Giuseppe, Zingales, Tiziano, Martin-Lagarde, Marine, Gastaud, René, Lagage, Pierre-Olivier (The Astronomical Journal)

A machine learning approach to galaxy properties: joint redshift-stellar mass probability distributions with Random Forest

We demonstrate that highly accurate joint redshift-stellar mass probability distribution functions (PDFs) can be obtained using the Random Forest (RF) machine learning (ML) algorithm, even with few photometric bands available. As an example, we use the Dark Energy Survey (DES), combined with the COSMOS2015 catalogue for redshifts and stellar masses. We build two ML models: one containing deep photometry in the griz bands, and the second reflecting the photometric scatter present in the main DES survey, with carefully constructed representative training data in each case. []

April 2021: Mucesh, S., Hartley, W. G., Palmese, A., Lahav, O., Whiteway, L., et al (Monthly Notices of the Royal Astronomical Society)

Evaluating hydrodynamical simulations with green valley galaxies

We test cosmological hydrodynamical simulations of galaxy formation regarding the properties of the blue cloud (BC), green valley (GV), and red sequence (RS), as measured on the 4000Å break strength versus stellar mass plane at z = 0.1. We analyse the RefL0100N1504 run of EAGLE and the TNG100 run of IllustrisTNG project, by comparing them with the Sloan Digital Sky Survey (SDSS), while taking into account selection bias. Our analysis focuses on the GV, within stellar mass $\log \, \mathrm{{\it M}_\star /M_{\odot }} \simeq 10\!-\!11$ , selected from the bimodal distribution of galaxies on the Dn(4000) versus stellar mass plane, following Angthopo et al. []

April 2021: Angthopo, J., Negri, A., Ferreras, I., de la Rosa, I. G., Dalla Vecchia, C., et al (Monthly Notices of the Royal Astronomical Society)

SSSpaNG! stellar spectra as sparse, data-driven, non-Gaussian processes

Upcoming million-star spectroscopic surveys have the potential to revolutionize our view of the formation and chemical evolution of the Milky Way. Realizing this potential requires automated approaches to optimize estimates of stellar properties, such as chemical element abundances, from the spectra. The sheer volume and quality of the observations strongly motivate that these approaches should be driven by the data. []

March 2021: Feeney, Stephen M., Wandelt, Benjamin D., Ness, Melissa K. (Monthly Notices of the Royal Astronomical Society)

Quantifying the global parameter tensions between ACT, SPT, and Planck

The overall cosmological parameter tension between the Atacama Cosmology Telescope 2020 fourth data release (ACT) and Planck 2018 data within the concordance cosmological model is quantified using the Suspiciousness statistic to be 2.6 σ . Between ACT and the South Pole Telescope (SPT) we find a tension of 2.4 σ , and 2.8 σ between ACT and Planck +SPT combined. While it is unclear whether the tension is caused by statistical fluctuations, systematic effects or new physics, caution should be exercised in combining these cosmic microwave background datasets in the context of the Λ CDM standard model of the universe.

March 2021: Handley, Will, Lemos, Pablo (Physical Review D)

Hydrodynamic escape of mineral atmosphere from hot rocky exoplanet. I. Model description

Recent exoplanet statistics indicate that photo-evaporation has a great impact on the mass and bulk composition of close-in low-mass planets. While there are many studies addressing photo-evaporation of hydrogen- or water-rich atmospheres, no detailed investigation regarding rocky vapour atmospheres (or mineral atmospheres) has been conducted. Here, we develop a new 1D hydrodynamic model of the ultraviolet (UV)-irradiated mineral atmosphere composed of Na, Mg, O, Si, their ions and electrons, including molecular diffusion, thermal conduction, photo-/thermochemistry, X-ray and UV heating, and radiative line cooling (i.e. []

March 2021: Ito, Yuichi, Ikoma, Masahiro (Monthly Notices of the Royal Astronomical Society)

ExoMol line lists - XLI. High-temperature molecular line lists for the alkali metal hydroxides KOH and NaOH

Potassium hydroxide (KOH) and sodium hydroxide (NaOH) are expected to occur in the atmospheres of hot rocky super-Earth exoplanets but a lack of spectroscopic data is hampering their potential detection. Using robust first-principles methodologies, comprehensive molecular line lists for KOH and NaOH that are applicable for temperatures up to T = 3500 K are presented. The KOH OYT4 line list covers the 0-6000 cm-1 (wavelengths λ > 1.67 µm) range and comprises 38 billion transitions between 7.3 million energy levels with rotational excitation up to J = 255. []

March 2021: Owens, A., Tennyson, J., Yurchenko, S. N. (Monthly Notices of the Royal Astronomical Society)

Constraining cosmology using galaxy position angle-only cosmic shear

We investigate cosmological parameter inference from realistic simulated weak lensing image data using only galaxy position angles, as opposed to full-ellipticity information. We demonstrate that input shear fields can be accurately reconstructed using only the statistics of source galaxy position angles and that, from these shear fields, we can successfully recover power spectra and infer the input cosmology. This paper builds on previous work on angle-only weak lensing estimation by extending the method to deal with variable and anisotropic point spread function (PSF) convolution and variable shear fields. []

March 2021: Whittaker, Lee (Monthly Notices of the Royal Astronomical Society)

H α fluxes and extinction distances for planetary nebulae in the IPHAS survey of the northern galactic plane

We report H α filter photometry for 197 Northern hemisphere planetary nebulae (PNe) obtained using imaging data from the IPHAS survey. H α+[N II] fluxes were measured for 46 confirmed or possible PNe discovered by the IPHAS survey and for 151 previously catalogued PNe that fell within the area of the northern Galactic Plane surveyed by IPHAS. After correcting for [N II] emission admitted by the IPHAS H α filter, the resulting H α fluxes were combined with published radio free-free fluxes and H β fluxes, in order to estimate mean optical extinctions to 143 PNe using ratios involving their integrated Balmer line fluxes and their extinction-free radio fluxes. []

March 2021: Dharmawardena, Thavisha E., Barlow, M. J., Drew, J. E., Seales, A., Sale, S. E., et al (Monthly Notices of the Royal Astronomical Society)

PyLightcurve-torch: a transit modeling package for deep learning applications in PyTorch

We present a new open source python package, based on PyLightcurve and PyTorch Paszke et al., tailored for efficient computation and automatic differentiation of exoplanetary transits. The classes and functions implemented are fully vectorised, natively GPU-compatible and differentiable with respect to the stellar and planetary parameters. This makes PyLightcurve-torch suitable for traditional forward computation of transits, but also extends the range of possible applications with inference and optimization algorithms requiring access to the gradients of the physical model. []

March 2021: Morvan, Mario, Tsiaras, Angelos, Nikolaou, Nikolaos, Waldmann, Ingo P. (Publications of the Astronomical Society of the Pacific)

Group-scale intrinsic galaxy alignments in the Illustris-TNG and MassiveBlack-II simulations

We study the alignments of satellite galaxies, and their anisotropic distribution, with respect to location and orientation of their host central galaxy in MassiveBlack-II (MB-II) and IllustrisTNG simulations. We find that: the shape of the satellite system in haloes of mass ($\gt 10^{13}\, h^{-1}\, \mathrm{M}_{\odot }$) is well aligned with the shape of the central galaxy at z = 0.06 with the mean alignment between the major axes being ~Δθ = 12° when compared to a uniform random distribution; that satellite galaxies tend to be anisotropically distributed along the major axis of the central galaxy with a stronger alignment in haloes of higher mass or luminosity; and that the satellite distribution is more anisotropic for central galaxies with lower star formation rate, which are spheroidal, and for red central galaxies. Radially, we find that satellites tend to be distributed along the major axis of the shape of the stellar component of central galaxies at smaller scales and the dark matter component on larger scales. []

March 2021: Tenneti, Ananth, Kitching, Thomas D., Joachimi, Benjamin, Di Matteo, Tiziana (Monthly Notices of the Royal Astronomical Society)

The PAU Survey: Intrinsic alignments and clustering of narrow-band photometric galaxies

We present the first measurements of the projected clustering and intrinsic alignments (IA) of galaxies observed by the Physics of the Accelerating Universe Survey (PAUS). With photometry in 40 narrow optical passbands (4500 Å-8500 Å), the quality of photometric redshift estimation is σz ∼ 0.01(1 + z) for galaxies in the 19 deg2 Canada-France-Hawaii Telescope Legacy Survey W3 field, allowing us to measure the projected 3D clustering and IA for flux-limited, faint galaxies (i < 22.5) out to z ∼ 0.8. To measure two-point statistics, we developed, and tested with mock photometric redshift samples, `cloned' random galaxy catalogues which can reproduce data selection functions in 3D and account for photometric redshift errors. []

February 2021: Johnston, Harry, Joachimi, Benjamin, Norberg, Peder, Hoekstra, Henk, Eriksen, Martin, et al (Astronomy and Astrophysics)

The cosmic abundance of cold gas in the local Universe

We determine the cosmic abundance of molecular hydrogen (H2) in the local Universe from the xCOLD GASS survey. To constrain the H2 mass function at low masses and correct for the effect of the lower stellar mass limit of $10^9 \, \mathrm{M}_{\odot }$ in the xCOLD GASS survey, we use an empirical approach based on an observed scaling relation between star formation rate and gas mass. We also constrain the H I and H I+H2 mass functions using the xGASS survey and compare them to the H I mass function from the ALFALFA survey. []

February 2021: Fletcher, Thomas J., Saintonge, Amélie, Soares, Paula S., Pontzen, Andrew (Monthly Notices of the Royal Astronomical Society)

EDGE: a new approach to suppressing numerical diffusion in adaptive mesh simulations of galaxy formation

We introduce a new method to mitigate numerical diffusion in adaptive mesh refinement (AMR) simulations of cosmological galaxy formation, and study its impact on a simulated dwarf galaxy as part of the 'EDGE' project. The target galaxy has a maximum circular velocity of $21\, \mathrm{km}\, \mathrm{s}^{-1}$ but evolves in a region that is moving at up to $90\, \mathrm{km}\, \mathrm{s}^{-1}$ relative to the hydrodynamic grid. In the absence of any mitigation, diffusion softens the filaments feeding our galaxy. []

February 2021: Pontzen, Andrew, Rey, Martin P., Cadiou, Corentin, Agertz, Oscar, Teyssier, Romain, et al (Monthly Notices of the Royal Astronomical Society)

Likelihood-free inference with neural compression of DES SV weak lensing map statistics

In many cosmological inference problems, the likelihood (the probability of the observed data as a function of the unknown parameters) is unknown or intractable. This necessitates approximations and assumptions, which can lead to incorrect inference of cosmological parameters, including the nature of dark matter and dark energy, or create artificial model tensions. Likelihood-free inference covers a novel family of methods to rigorously estimate posterior distributions of parameters using forward modelling of mock data. []

February 2021: Jeffrey, Niall, Alsing, Justin, Lanusse, François (Monthly Notices of the Royal Astronomical Society)

GenetIC—A New Initial Conditions Generator to Support Genetically Modified Zoom Simulations

We present genetIC, a new code for generating initial conditions for cosmological N-body simulations. The code allows precise, user-specified alterations to be made to arbitrary regions of the simulation (while maintaining consistency with the statistical ensemble). These "genetic modifications" allow, for example, the history, mass, or environment of a target halo to be altered in order to study the effect on their evolution. []

February 2021: Stopyra, Stephen, Pontzen, Andrew, Peiris, Hiranya, Roth, Nina, Rey, Martin P. (The Astrophysical Journal Supplement Series)

SUPER. IV. CO(J = 3-2) properties of active galactic nucleus hosts at cosmic noon revealed by ALMA

Feedback from active galactic nuclei (AGN) is thought to be key in shaping the life cycle of their host galaxies by regulating star-formation activity. Therefore, to understand the impact of AGN on star formation, it is essential to trace the molecular gas out of which stars form. In this paper we present the first systematic study of the CO properties of AGN hosts at z ≈ 2 for a sample of 27 X-ray selected AGN spanning two orders of magnitude in AGN bolometric luminosity (log Lbol / erg s-1 = 44.7 - 46.9) by using ALMA Band 3 observations of the CO(3-2) transition (∼1″ angular resolution). []

February 2021: Circosta, C., Mainieri, V., Lamperti, I., Padovani, P., Bischetti, M., et al (Astronomy and Astrophysics)

Radiation Hydrodynamics of Turbulent H II Regions in Molecular Clouds: A Physical Origin of LyC Leakage and the Associated Lyα Spectra

We examine Lyman continuum (LyC) leakage through H II regions regulated by turbulence and radiative feedback in a giant molecular cloud in the context of fully coupled radiation hydrodynamics (RHD). The physical relations of the LyC escape with H I covering fraction, kinematics, ionizing photon production efficiency, and emergent Lyα line profiles are studied using a series of RHD turbulence simulations performed with RAMSES-RT. The turbulence-regulated mechanism allows ionizing photons to leak out at early times before the onset of supernova feedback. []

February 2021: Kakiichi, Koki, Gronke, Max (The Astrophysical Journal)

KiDS-1000 methodology: Modelling and inference for joint weak gravitational lensing and spectroscopic galaxy clustering analysis

We present the methodology for a joint cosmological analysis of weak gravitational lensing from the fourth data release of the ESO Kilo-Degree Survey (KiDS-1000) and galaxy clustering from the partially overlapping Baryon Oscillation Spectroscopic Survey (BOSS) and the 2-degree Field Lensing Survey (2dFLenS). Cross-correlations between BOSS and 2dFLenS galaxy positions and source galaxy ellipticities have been incorporated into the analysis, necessitating the development of a hybrid model of non-linear scales that blends perturbative and non-perturbative approaches, and an assessment of signal contributions by astrophysical effects. All weak lensing signals were measured consistently via Fourier-space statistics that are insensitive to the survey mask and display low levels of mode mixing. []

February 2021: Joachimi, B., Lin, C. -A., Asgari, M., Tröster, T., Heymans, C., et al (Astronomy and Astrophysics)

The ExoMolOP database: Cross sections and k-tables for molecules of interest in high-temperature exoplanet atmospheres

Here we present a publicly available database of opacities for molecules of astrophysical interest named ExoMolOP that has been compiled for over 80 species, and is based on the latest line list data from the ExoMol, HITEMP, and MoLLIST databases. These data are generally suitable for characterising high-temperature exoplanet or cool stellar and substellar atmospheres, and have been computed at a variety of pressures and temperatures, with a few molecules included at room temperature only from the HITRAN database. The data are formatted in different ways for four different exoplanet atmosphere retrieval codes; ARCiS, TauREx, NEMESIS, and petitRADTRANS, and include both cross sections (at R = λ/Δλ = 15000) and k-tables (at R = λ/Δλ = 1000) for the 0.3-50 μm wavelength region. []

February 2021: Chubb, Katy L., Rocchetto, Marco, Yurchenko, Sergei N., Min, Michiel, Waldmann, Ingo, et al (Astronomy and Astrophysics)

Detectability of Rocky-Vapour atmospheres on super-Earths with Ariel

Ariel will mark the dawn of a new era as the first large-scale survey characterising exoplanetary atmospheres with science objectives to address fundamental questions about planetary composition, evolution and formation. In this study, we explore the detectability of atmospheres vaporised from magma oceans on dry, rocky Super-Earths orbiting very close to their host stars. The detection of such atmospheres would provide a definitive piece of evidence for rocky planets but are challenging measurements with currently available instruments due to their small spectral signatures. []

January 2021: Ito, Yuichi, Changeat, Quentin, Edwards, Billy, Al-Refaie, Ahmed, Tinetti, Giovanna, et al (Experimental Astronomy)

Hubble WFC3 Spectroscopy of the Habitable-zone Super-Earth LHS 1140 b

Atmospheric characterization of temperate, rocky planets is the holy grail of exoplanet studies. These worlds are at the limits of our capabilities with current instrumentation in transmission spectroscopy and challenge our state-of-the-art statistical techniques. Here we present the transmission spectrum of the temperate super-Earth LHS 1140b using the Hubble Space Telescope (HST). []

January 2021: Edwards, Billy, Changeat, Quentin, Mori, Mayuko, Anisman, Lara O., Morvan, Mario, et al (The Astronomical Journal)

Quenching and morphological evolution due to circumgalactic gas expulsion in a simulated galaxy with a controlled assembly history

We examine the influence of dark matter halo assembly on the evolution of a simulated ∼L galaxy. Starting from a zoom-in simulation of a star-forming galaxy evolved with the EAGLE galaxy formation model, we use the genetic modification technique to create a pair of complementary assembly histories: one in which the halo assembles later than in the unmodified case, and one in which it assembles earlier. Delayed assembly leads to the galaxy exhibiting a greater present-day star formation rate than its unmodified counterpart, while in the accelerated case the galaxy quenches at z ≃ 1, and becomes spheroidal. []

January 2021: Davies, Jonathan J., Crain, Robert A., Pontzen, Andrew (Monthly Notices of the Royal Astronomical Society)

How to build a catalogue of linearly evolving cosmic voids

Cosmic voids provide a powerful probe of the origin and evolution of structures in the Universe because their dynamics can remain near-linear to the present day. As a result, they have the potential to connect large-scale structure at late times to early Universe physics. Existing 'watershed'-based algorithms, however, define voids in terms of their morphological properties at low redshift. []

January 2021: Stopyra, Stephen, Peiris, Hiranya V., Pontzen, Andrew (Monthly Notices of the Royal Astronomical Society)

The Hubble WFC3 Emission Spectrum of the Extremely Hot Jupiter KELT-9b

Recent studies of ultra-hot Jupiters suggested that their atmospheres could have thermal inversions due to the presence of optical absorbers such as titanium oxide (TiO), vanadium oxide (VO), iron hydride (FeH), and other metal hydride/oxides. However, it is expected that these molecules would thermally dissociate at extremely high temperatures, thus leading to featureless spectra in the infrared. KELT-9 b, the hottest exoplanet discovered so far, is thought to belong to this regime and host an atmosphere dominated by neutral hydrogen from dissociation and atomic/ionic species. []

January 2021: Changeat, Quentin, Edwards, Billy (The Astrophysical Journal)

Machine Learning for Searching the Dark Energy Survey for Trans-Neptunian Objects

In this paper we investigate how implementing machine learning could improve the efficiency of the search for Trans-Neptunian Objects (TNOs) within Dark Energy Survey (DES) data when used alongside orbit fitting. The discovery of multiple TNOs that appear to show a similarity in their orbital parameters has led to the suggestion that one or more undetected planets, an as yet undiscovered "Planet 9", may be present in the outer solar system. DES is well placed to detect such a planet and has already been used to discover many other TNOs. []

January 2021: Henghes, B., Lahav, O., Gerdes, D. W., Lin, H. W., Morgan, R., et al (Publications of the Astronomical Society of the Pacific)

Water ice deposition and growth in molecular clouds

In interstellar clouds, the deposition of water ice on to grains only occurs at visual extinctions above some threshold value (Ath). At extinctions greater than Ath, there is a (near-linear) correlation between the inferred column density of the water ice and AV. For individual cloud complexes such as Taurus, Serpens, and ρ-Ophiuchi, Ath and the gradients of the correlation are very similar along all lines of sight. []

January 2021: Rawlings, Jonathan M. C., Williams, D. A. (Monthly Notices of the Royal Astronomical Society)

Centrally concentrated molecular gas driving galactic-scale ionized gas outflows in star-forming galaxies

We perform a joint analysis of high spatial resolution molecular gas and star-formation rate (SFR) maps in main-sequence star-forming galaxies experiencing galactic-scale outflows of ionized gas. Our aim is to understand the mechanism that determines which galaxies are able to launch these intense winds. We observed CO(1→0) at 1-arcsec resolution with ALMA in 16 edge-on galaxies, which also have 2-arcsec spatial-resolution optical integral field observations from the SAMI Galaxy Survey. []

January 2021: Hogarth, L. M., Saintonge, A., Cortese, L., Davis, T. A., Croom, S. M., et al (Monthly Notices of the Royal Astronomical Society)

Double-peaked Lyman α emission at z = 6.803: a reionization-era galaxy self-ionizing its local H II bubble

We report the discovery of a double-peaked Lyman α profile in a galaxy at z = 6.803, A370p_z1, in the parallel Frontier Field of Abell 370. The velocity separation between the blue and red peaks of the Lyman α profile ( $\Delta v=101_{-19}^{+38} (\pm 48)\, \rm km\, \rm s^{-1}$ ) suggests an extremely high escape fraction of ionizing photons $\gt 59(51){{\ \rm per\ cent}} (2\sigma)$ . The spectral energy distribution indicates a young (50 Myr), star-forming ( $12\pm 6 \, \rm {M}_\odot \rm {yr}^{-1}$ ) galaxy with an IRAC excess implying strong [O III] + H β emission. []

January 2021: Meyer, Romain A., Laporte, Nicolas, Ellis, Richard S., Verhamme, Anne, Garel, Thibault (Monthly Notices of the Royal Astronomical Society)

On the Compatibility of Ground-based and Space-based Data: WASP-96 b, an Example

The study of exoplanetary atmospheres relies on detecting minute changes in the transit depth at different wavelengths. To date, a number of ground- and space-based instruments have been used to obtain transmission spectra of exoplanets in different spectral bands. One common practice is to combine observations from different instruments in order to achieve a broader wavelength coverage. []

January 2021: Yip, Kai Hou, Changeat, Quentin, Edwards, Billy, Morvan, Mario, Chubb, Katy L., et al (The Astronomical Journal)

Sum of the masses of the Milky Way and M31: A likelihood-free inference approach

We use density estimation likelihood-free inference, Λ cold dark matter simulations of ∼2 M galaxy pairs, and data from Gaia and the Hubble Space Telescope to infer the sum of the masses of the Milky Way and Andromeda (M31) galaxies, the two main components of the local group. This method overcomes most of the approximations of the traditional timing argument, makes the writing of a theoretical likelihood unnecessary, and allows the nonlinear modeling of observational errors that take into account correlations in the data and non-Gaussian distributions. We obtain an M200 mass estimate MMW +M 31=4. []

January 2021: Lemos, Pablo, Jeffrey, Niall, Whiteway, Lorne, Lahav, Ofer, Libeskind, Noam, et al (Physical Review D)