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IPM
30
YEARS OLD

“School of Astronomy”

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Paper   IPM / Astronomy / 15489
School of Astronomy
  Title:   Chandra centres for COSMOS X-ray galaxy groups: Differences in stellar properties between central dominant and offset brightest group galaxies
  Author(s): 
1.  Ghassem . Gozaliasl
2.  Alexis . Finoguenov
3.  Masayuki . Tanaka
4.  Klaus . Dolag
5.  Francesco . Montanari
6.  Charles . C. Kirkpatrick
7.  Eleni . Vardoulaki
8.  Habib . G. Khosroshahi
9.  Mara . Salvato
10.  Clotilde . Laigle
11.  Henry . J. McCracken
12.  Olivier . Ilbert
13.  Nico . Cappelluti
14.  Emanuele . Daddi
15.  Guenther . Hasinger
16.  Peter . Capak
17.  Nick Z. . Scoville
18.  Sune . Toft
19.  Francesca . Civano
20.  Richard . E. Griffiths
21.  Michael . Balogh
22.  Yanxia . Li
23.  Jussi . Ahoranta
24.  Simona . Mei
25.  Angela . Iovino
26.  Bruno . M. B. Henriques
27.  Ghazaleh . Erfanianfar
  Status:   Published
  Journal: MNRAS
  Vol.:  483
  Year:  2018
  Supported by:            ipm IPM
  Abstract:
We present the results of a search for galaxy clusters and groups in the ∼2 square degree 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 3×10−16ergscm−2s−1 in 0.5-2 keV range, and identify 247 X-ray groups with M200c=8×1012−3×1014M⊙ 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 0.3dex, in agreement with model prediction. The observed and predicted lognormal scatter in the stellar mass of both low- and large-offset BGGs at fixed halo mass is ∼0.3dex.

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