A second catalog of compact sources delivered by Planck

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The Planck Collaboration has just put online a new catalog highly anticipated by the community. This second catalog uses the complete mission data to identify tens of thousands of compact sources. For the first time, the polarization information is also available for several hundreds of them. Thus this new catalog surpasses its predecessors in quantity but also in quality. Astronomers will be able to use it for a wide variety of studies.

Analysis of temperature and polarization data in the nine frequency bands includes point source identification and characterization. This work has resulted in the production of a catalogue of galactic and extra-galactic sources, available to the entire community.

Galactic coordinate map of the distribution of a selection of compact sources seen by Planck from 30 to 857 GHz. The sources identified in the 30 GHz channel are shown in red, those identified at 143 GHz in blue and finally those detected at 857 GHz in green. Credits: ESA – Planck collaboration

A more complete and reliable catalogue

With nearly five complete sky covers with the HFI instrument and more than eight with the LFI instrument, this catalogue significantly surpasses the previous lists delivered by Planck in 2011 and 2013. Improved data analysis has also contributed to this result, which is more complete but also more reliable than the previous ones.

But that’s not all: when it was large enough to be detected, polarization information, accessible from 30 to 353 GHz, is also made available, in addition to the position and total intensity of the source.

Multiple uses for this catalogue

This catalogue is part of the Planck legacy archive: the data are public in a format adapted to astrophysicists’ tools. Sources can be searched by name or coordinates, the feed is available in various methods so that everyone can choose the optimal technique for their preferred source.

This tool contains a real celestial menagerie: radio-galaxies, blazars, galaxies shining in the infrared, galaxy clusters, supernova remnants, cold molecular cloud cores, stars in their dust shells and many others that remain to be identified. The fields of astronomy that will benefit from these results are therefore very broad!

Understanding the physics of a source generally requires a multi-wavelength study. With its nine frequencies that are not or hardly accessible from the ground and its complete sky coverage, this catalogue perfectly complements the data from radio-galaxies or molecular clouds for example.

But this tool is also valuable for those studying fossil radiation. Indeed, it is essential to mask foreground point sources when analyzing the primordial signal. This information is thus available over the entire sky, in temperature and polarization.

Centaurus A seen by Planck in intensity (top images) and polarization (bottom images) from 30 to 353 GHz. This information complements the infrared, visible or X-ray observations. Credits: ESA – Planck collaboration

Further Resources

  • Web INSU : “Le second catalogue de sources compactes livré par Planck”
  • Web Planck HFI : “Un nouvel outil pour les astronomes : le second catalogue de sources compactes livré par Planck”

Contact IRAP :

  • Ludovic Montier, ludovic.montier@irap.omp.eu – Tél 05 61 55 65 51

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