# Brightest group galaxies-II : the relative contribution of BGGs to the total baryon content of groups at z <1.3

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http://hdl.handle.net/10138/233832

#### Citation

Gozaliasl , G , Finoguenov , A , Khosroshahi , H G , Henriques , B M B , Tanaka , M , Ilbert , O , Wuyts , S , McCracken , H J & Montanari , F 2018 , ' Brightest group galaxies-II : the relative contribution of BGGs to the total baryon content of groups at z <1.3 ' Monthly Notices of the Royal Astronomical Society , vol. 475 , no. 2 , pp. 2787-2808 . DOI: 10.1093/mnras/sty003

 Title: Brightest group galaxies-II : the relative contribution of BGGs to the total baryon content of groups at z <1.3 Author: Gozaliasl, Ghassem; Finoguenov, Alexis; Khosroshahi, Habib G.; Henriques, Bruno M. B.; Tanaka, Masayuki; Ilbert, Olivier; Wuyts, Stijn; McCracken, Henry J.; Montanari, Francesco Other contributor: University of Helsinki, Helsinki Institute of Physics University of Helsinki, Department of Physics University of Helsinki, Helsinki Institute of Physics Date: 2018-01-04 Language: eng Number of pages: 22 Belongs to series: Monthly Notices of the Royal Astronomical Society ISSN: 0035-8711 DOI: https://doi.org/10.1093/mnras/sty003 URI: http://hdl.handle.net/10138/233832 Abstract: We performed a detailed study of the evolution of the star formation rate (SFR) and stellar mass of the brightest group galaxies (BGGs) and their relative contribution to the total baryon budget within $R_{200}$ ($f^{BGG}_{b,200}$). The sample comprises 407 BGGs selected from X-ray galaxy groups ($M_{200}=10^{12.8}-10^{14} \;M_{\odot}$) out to $z\sim1.3$ identified in the COSMOS, XMM-LSS, and AEGIS fields. We find that BGGs constitute two distinct populations of quiescent and star-forming galaxies and their mean SFR is $\sim2$ dex higher than the median SFR at $z 2$ dex. The mean (median) of stellar mass of BGGs has grown by $0.3$ dex since $z=1.3$ to the present day. We show that up to $\sim45\%$ of the stellar mass growth in a star-forming BGG can be due to its star-formation activity. With respect to $f^{BGG}_{b,200}$, we find it to increase with decreasing redshift by $\sim0.35$ dex while decreasing with halo mass in a redshift dependent manner. We show that the slope of the relation between $f^{BGG}_{b,200}$ and halo mass increases negatively with decreasing redshift. This trend is driven by an insufficient star-formation in BGGs, compared to the halo growth rate. We separately show the BGGs with the 20\% highest $f^{BGG}_{b,200}$ are generally non-star-forming galaxies and grow in mass by processes not related to star formation (e.g., dry mergers and tidal striping). We present the $M_\star-M_h$ and $M_\star/M_h-M_h$ relations and compare them with semi-analytic model predictions and a number of results from the literature. We quantify the intrinsic scatter in stellar mass of BGGs at fixed halo mass ($\sigma_{log M_{\star}}$) and find that $\sigma_{log M_{\star}}$ increases from 0.3 dex at $z\sim0.2$ to 0.5 dex at $z\sim1.0$ due to the bimodal distribution of stellar mass. Subject: astro-ph.GA 115 Astronomy, Space science Rights:
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