Chandra centres for COSMOS X-ray galaxy groups: differences in stellar properties between central dominant and offset brightest group galaxies

Journal
Date Issued
2019
Author(s)
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
•
•
Henriques, Bruno M. B.
•
Erfanianfar, Ghazaleh
DOI
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× 10^{-16} erg cm^{-2 s}^{-1} in the 0.5-2 keV range, and identify 247 X-ray groups with M_{ 200c}=8× 10^{12}-3× 10^{14} M_{☉} 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.
Volume
483
Issue
3
Start page
3545
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2019MNRAS.483.3545G
Rights
open.access
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