Chandra centres for COSMOS X-ray galaxy groups: differences in stellar properties between central dominant and offset brightest group galaxies. Issue 3 (27th November 2018)

• Record Type: Journal Article
• Authors: Gozaliasl, Ghassem; Finoguenov, Alexis; Tanaka, Masayuki; Dolag, Klaus; Montanari, Francesco; Kirkpatrick, Charles C; Vardoulaki, Eleni; Khosroshahi, Habib G; Salvato, Mara; Laigle, Clotilde; McCracken, Henry J; Ilbert, Olivier; Cappelluti, Nico; Daddi, Emanuele; Hasinger, Guenther; Capak, Peter; Scoville, Nick Z; Toft, Sune; Civano, Francesca; Griffiths, Richard E; Balogh, Michael; Li, Yanxia; Ahoranta, Jussi; Mei, Simona; Iovino, Angela; Henriques, Bruno M B; Erfanianfar, Ghazaleh
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 483:Issue 3(2019)
• Page Start: 3545
• Page End: 3565
• Publication Date: 2018-11-27
• Subjects: galaxies: clusters: general -- galaxies: evolution -- galaxies: groups: general -- galaxies: statistics -- galaxies: stellar content -- X-rays: galaxies: clusters; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty3203
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present the results of a search for galaxy clusters and groups in the ∼2 deg 2 of the COSMOS field using all available X-ray observations from the XMM–Newton and Chandra observatories. We reach an X-ray flux limit of$3\times 10^{-16} \, \mathrm{erg\, cm^{-2}\, s}^{-1}$ in the 0.5–2 keV range, and identify 247 X-ray groups with$M_{\mathrm{ 200c}}=8\times 10^{12}\text{--}3\times 10^{14}\, \mathrm{M}_{\odot }$ at a redshift range of 0.08 ≤$z$ < 1.53, using the multiband photometric redshift and the master spectroscopic redshift catalogues of the COSMOS. The X-ray centres of groups are determined using high-resolution Chandra imaging. We investigate the relations between the offset of the brightest group galaxies (BGGs) from halo X-ray centre and group properties and compare with predictions from semi-analytic models and hydrodynamical simulations. We find that BGG offset decreases with both increasing halo mass and decreasing redshift with no strong dependence on the X-ray flux and SNR. We show that the BGG offset decreases as a function of increasing magnitude gap with no considerable redshift-dependent trend. The stellar mass of BGGs in observations extends over a wider dynamic range compared to model predictions. At$z$ < 0.5, the central dominant BGGs become more massive than those with large offsets by up to 0.3 dex, in agreement with model prediction. The observed and predicted log-normal scatter in the stellar mass of both low- and large-offset BGGs at fixed halo mass is ∼0.3 dex.