A1 Refereed original research article in a scientific journal
Chandra centres for COSMOS X-ray galaxy groups: differences in stellar properties between central dominant and offset brightest group galaxies
Authors: Gozaliasl G, Finoguenov A, Tanaka M, Dolag K, Montanari F, Kirkpatrick CC, Vardoulaki E, Khosroshahi HG, Salvato M, Laigle C, McCracken HJ, Ilbert O, Cappelluti N, Daddi E, Hasinger G, Capak P, Scoville NZ, Toft S, Civano F, Griffiths RE, Balogh M, Li YX, Ahoranta J, Mei S, Iovino A, Henriques BMB, Erfanianfar G, Erfanianfar G
Publisher: OXFORD UNIV PRESS
Publication year: 2019
Journal: Monthly Notices of the Royal Astronomical Society
Journal name in source: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Journal acronym: MON NOT R ASTRON SOC
Volume: 483
Issue: 3
First page : 3545
Last page: 3565
Number of pages: 21
ISSN: 0035-8711
eISSN: 1365-2966
DOI: https://doi.org/10.1093/mnras/sty3203
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/39914979
We present the results of a search for galaxy clusters and groups in the similar to 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 x 10(-16) erg cm(-2) s(-1) in the 0.5-2 keV range, and identify 247 X-ray groups with M-200c = 8 x 10(12)-3 x 10(14)M(circle dot) 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 similar to 0.3 dex.
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