Mar 15 – 20, 2020
Europe/Berlin timezone

The X-ray Properties of Optically Selected Galaxy Groups

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The overlap between the GAMA optical survey and the XXL X-ray survey creates an exciting opportunity to explore galaxy groups across multiple wavelengths with independent selection criteria. This overlap region contains 234 galaxy groups with five or more members optically detected by GAMA. Using forced X-ray aperture photometry on these groups allows the study of their X-ray properties in the regime of very low signal-to-noise X-ray data. Not only does this sample of galaxy groups extend to lower X-ray luminosities than X-ray selected samples, but also has different sources of selection bias. The X-ray luminosity function (XLF) of the sample was explored to look for evidence for non-gravitational processes such as AGN-feedback at low X-ray luminosities which may modify the form of the XLF. Preliminary results are consistent with the extrapolation of the XLF from X-ray selected samples at higher luminosities. Following from this, the data will be used to infer the form of the scaling relation between X-ray luminosity and mass at lower masses and luminosities than has previously been possible in X-ray selected samples. This approach can be translated to eROSITA data, combined with future all-sky optical surveys to constrain the X-ray properties of galaxy groups and clusters in the limits of high redshift and low mass.

Presenter status Conference attendee

Primary author

Mr Cai Wood (University of Bristol)


Ben Maughan (University of Bristol)

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