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

TY - JOUR

T1 - Chandra centres for COSMOS X-ray galaxy groups

T2 - differences in stellar properties between central dominant and offset brightest group galaxies

AU - Gozaliasl, G.

AU - Finoguenov, A.

AU - Tanaka, M.

AU - Dolag, K.

AU - Montanari, F.

AU - Kirkpatrick, C.~C.

AU - Vardoulaki, E.

AU - Khosroshahi, H.~G.

AU - Salvato, M.

AU - Laigle, C.

AU - McCracken, H.~J.

AU - Ilbert, O.

AU - Cappelluti, N.

AU - Daddi, E.

AU - Hasinger, G.

AU - Capak, P.

AU - Scoville, N.~Z.

AU - Toft, S.

AU - Civano, F.

AU - Griffiths, R.~E.

AU - Balogh, M.

AU - Li, Y.

AU - Ahoranta, J.

AU - Mei, S.

AU - Iovino, A.

AU - Henriques, B.~M.~B.

AU - Erfanianfar, G.

PY - 2019/3/1

Y1 - 2019/3/1

N2 - We present the results of a search for galaxy clusters and groups in the ∼2 deg2 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 M200c = 8 × 1012-3 × 1014 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.

AB - We present the results of a search for galaxy clusters and groups in the ∼2 deg2 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 M200c = 8 × 1012-3 × 1014 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.

KW - galaxies: clusters: general, galaxies: evolution, galaxies: groups: general, galaxies: statistics, galaxies: stellar content, X-rays: galaxies: clusters

U2 - 10.1093/mnras/sty3203

DO - 10.1093/mnras/sty3203

M3 - Journal article

SN - 0035-8711

VL - 483

SP - 3545

EP - 3565

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

ER -