Mining the XMM-Newton Serendipitous Ultraviolet Source Survey

Prof. Mark Cropper and Dr Roberto Mignani

With nearly 800 000 sources, the Serendipitous Ultraviolet Source Survey (SUSS), derived from observations performed from the Optical Monitor (OM) aboard the XMM-Newton X-ray observatory, is the largest ultraviolet (UV) catalogue ever produced, providing positions, multi-band flux information up to six passbands, morphological classification, and multi-epoch data. The Thesis project is aimed at the scientific exploitation of the SUSS catalogue in different fields of stellar astrophysics and galaxy evolution.

The scientific potentials of the SUSS catalogue, together with the available, fully-reduced, OM data, are several. They range from stellar population studies, to the UV census of entire classes of objects, to the X-ray source identification, to the measurement of object variability and dynamics. For instance, the cross-correlations with available multi-band optical and infrared (IR) catalogues, like the Guide Star Catalogue 2 (GSC2) and the Two Micron All-Sky Survey (2MASS) allows one to study the spectrum of several thousand objects at once from the IR to the UV and to select new populations of objects with peculiar colours which will be prime targets or follow-up observations with X-SHOOTER, the UV-to-IR spectrograph at the Very Large Telescope (VLT). Moreover, information on the morphological classification allows one to build the first UV catalogue of extended sources, like galaxies, nebulae, and supernova remnants. Multi-epoch flux information allows one to search for variable objects (variable stars, transients, novae) and for high-proper motion objects. Finally, the SUSS object positions can be cross-correlated with those of X-ray sources detected by XMM-Newton, to yield their optical/UV identifications, and with several other object catalogues to study, for the first time on a broad observational basis, the properties of specific stellar populations, e.g. OB stars, White dwarfs, Wolf-Rayet stars in Planetary Nebulae, to carry out the first serendipitous UV survey of open clusters, and stellar associations, etc.

The PhD student is expected to carry out independent research activity in at least some of the projects outlined above, take part to the preparation of follow-up observing proposals with the VLT and other observing facilities, carry out observing runs at the telescope, and be responsible of the data reduction and analysis. Given the wide range of scientific potentials of the SUSS catalogue, interactions with all members of the MSSL Astro Group are encouraged.

The pointing and source number content of the SUSS catalogue

The pointing and source number content of the SUSS catalogue (blue circles) mapped onto a Mollweide equal area projection of the sky in Galactic longitude and latitude. Size and colour of the circles trace the source density in each pointing, where N is the number of sources detected in each field. The colour image in the background is the Infra-Red Astronomy Satellite (IRAS) 100 micron all-sky map (Schlegel, Finkbeiner & Davis, 1998), revealing the dust associated with the Galactic plane (Image Credit: Page et al., 20110, submitted to MNRAS).

Image of the galaxy NGC5204 in the Ursa Major Constellation

Image of the galaxy NGC5204 in the Ursa Major Constellation, obtained with the Optical Monitor camera aboard the XMM-Newton satellite. The image is a colour-composite of exposures obtained through different passbands (Image Credit: Vladimir Yershov, MSSL).

Image of the four units of the Very Large Telescope (VLT) array of the European Southern Observatory

Image of the four units of the Very Large Telescope (VLT) array of the European Southern Observatory (ESO), 2400 m on top of Cerro Paranal in Chile. The second unit from the left hosts the X-SHOOTER instrument which will be used for follow-ups of SUSS sources (Image Credit: ESO).