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CLoGS: the complete local-volume groups sample - poster for 20 years of Chandra meeting 2019

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posted on 2019-11-29, 16:39 authored by Ewan O'SullivanEwan O'Sullivan, Konstantinos Kolokythas, Jan M Vrtilek, Laurence P David, Schellenberger, Gerrit, myriam gitti, Simona Giacintucci, arif babul, Somak Raychaudhury
Galaxy groups are arguably the most important environment for our understanding of galaxy evolution, AGN feedback and the development of the hot intergalactic medium (IGM). Previous studies of groups in the nearby universe have either used optically-selected samples to examine galaxy populations, or X-ray selected samples (mainly derived from the ROSAT All-Sky Survey) to examine IGM properties. While these approaches have yielded important results, their selection methods mean they are subject to significant biases. We have created the the Complete Local-Volume Groups Sample (CLoGS), an optically-selected statistically-complete sample of 53 groups in the nearby Universe (D<80 Mpc), surveyed in the X-ray (Chandra and/or XMM-Newton), low-frequency radio (GMRT 235 & 610 MHz) and, for the dominant galaxies, molecular gas (IRAM 30m or APEX CO). This combination of data allows us to confirm which groups are fully virialized, examine their dynamical and thermal state, and investigate the role of AGN feedback in these systems. We will present results from the sample, showing that roughly one third of X-ray bright groups in the local universe are dynamically active (merging or sloshing), and roughly one third show evidence of ongoing or recent feedback from central AGN. We will examine the conditions under which feedback occurs in groups, and show examples of powerful outbursts which may dramatically over-heat the IGM. We will also show that a significant fraction (>30%) of the nearby group population has been missed by previous studies, and discuss the implications for future surveys.

(To be presented at the 20 years of Chandra Symposium in Boston, MA, 3-6 December 2019)

Further details of the CLoGS project can be found at http://www.sr.bham.ac.uk/~ejos/CLoGS.html

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