UCL Department of Physics and Astronomy

UCL Astrophysics Group

• Home
• Contact Us
• People
• Seminars
• Events
• Research Topics
  • Astro. Instrumentation
  • Cosmology
    • The Group
  • Planets & Atmospheres
  • Stars and Galaxies
• Undergraduate Studies
• PhD Admissions
• University of London Observatory
• Outreach
• Publications
• Useful Links
• Astrophysics Wiki Pages
• Vacancies page

Planck

The next great leap in our understanding of the early Universe comes from ESA's Planck Cosmic Microwave Background (CMB) satellite, which began surveying the microwave sky in the autumn of 2009. Planck gives us a definitive picture of the primordial fluctuations present in the CMB temperature, and also makes a great advance in our understanding of CMB polarization. Planck has already provided many new results in our understanding of the evolution of structure in the Universe and our own Galaxy: more information can be found here. The first cosmology results are eagerly anticipated in early 2013. Members of the UCL Cosmology Group  are using the Planck data to test the physics of the early Universe. 

Credit ESA press release: This multi-frequency all-sky image of the microwave sky has been composed using data from Planck covering the electromagnetic spectrum from 30 GHz to 857 GHz. The mottled structure of the CMB, with its tiny temperature fluctuations reflecting the primordial density variations from which today's cosmic structure originated, is clearly visible in the high-latitude regions of the map. The central band is the plane of our Galaxy. A large portion of the image is dominated by the diffuse emission from its gas and dust. The image was derived from data collected by Planck during its first all-sky survey and comes from observations taken between August 2009 and June 2010. This image is a low-resolution version of the full data set.

With the Planck High Frequency Instrument having completed its mission, the data received is allowing us to dig deeper in order to understand the performance of the instrument to a higher degree of precision. With the ongoing data analysis additional physical modelling of the optical components will help characterize small differences in instrument response due to different source spectral indices or contamination by strong spectral lines.

Credit: ESA and the HFI Consortium, IRAS. This image shows the local dust structures within 500 light-years of the Sun. It is a three-colour combination constructed from Planck's two highest frequency channels (545 and 857 GHz, corresponding to wavelengths of 540 and 350 micrometres), and an image at the shorter wavelength of 100 micrometres made by the IRAS satellite.

Planck's pixels are unlike many instruments where the optical features such as angular response in the sky or spectral efficiency are identical across the focal plane. Detecting microwaves requires macroscopic size pixels and each pixel is made singly. This in turn means that small differences between pixels need to be correctly characterised in order to correct for them at the later stage in data analysis.

Giorgio Savini in the Instrumentation Group is deeply involved in the characterization of the instrument, so that we can extract cosmological results to the high precision required by the science goals.