J/MNRAS/498/4095 X-ray active galactic nucleus at z∼0.4 (Noordeh+, 2020)
The environmental dependence of X-ray AGN activity at z∼0.4.
Noordeh E., Canning R.E.A., King A., Allen S.W., Mantz A., Morris R.G.,
Ehlert S., von der Linden A., Brandt W.N., Luo B., Xue Y.Q., Kelly P.
<Mon. Not. R. Astron. Soc., 498, 4095-4108 (2020)>
=2020MNRAS.498.4095N 2020MNRAS.498.4095N (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Active gal. nuclei ; X-ray sources ;
Redshifts ; Spectra, optical
Keywords: galaxies: active - galaxies: clusters: general -
X-rays: galaxies: clusters
Abstract:
We present an analysis of the X-ray active galactic nucleus (AGN)
population in a sample of seven massive galaxy clusters in the
redshift range 0.35<z<0.45. We utilize high-quality Chandra X-ray
imaging to robustly identify AGN and precisely determine cluster
masses and centroids. Follow-up VIsible Multi-Object Spectrograph
optical spectroscopy allows us to determine which AGN are cluster
members. Studying the subset of AGN with 0.5-8keV luminosities
>6.8x1042erg/s, within r~<2r500 (approximately the virial radius),
we find that the cluster AGN space density scales with cluster mass as
∼M(-2.0+0.8-0.9). This result rules out zero mass dependence of
the cluster X-ray AGN space density at the 2.5σ level. We
compare our cluster X-ray AGN sample to a control field with identical
selection and find that the cluster AGN fraction is significantly
suppressed relative to the field when considering the brightest
galaxies with V<21.5. For fainter galaxies, this difference is not
present. Comparing the X-ray hardness ratios of cluster member AGN to
those in the control field, we find no evidence for enhanced X-ray
obscuration of cluster member AGN. Lastly, we see tentative evidence
that disturbed cluster environments may contribute to enhanced AGN
activity.
Description:
Our study includes seven galaxy clusters drawn from the MAssive
Cluster Survey (MACS, Ebeling et al. 2010MNRAS.407...83E 2010MNRAS.407...83E) that are
visible from the south with redshifts between z=0.355 and 0.451 and
M500 values ranging from 5.5x1014 to 2.2x1015M☉. These are
some of the most massive and X-ray luminous clusters known, where we
would expect any environmental influence on AGN activity to be most
pronounced. We select a narrow redshift band in order to control for
possible redshift evolution in the cluster AGN population. This
particular band is well suited to VIMOS (VIsible Multi-Object
Spectrograph) spectroscopy (see Section 2.5). All clusters have been
observed with the Advanced CCD Imaging Spectrometer (ACIS) aboard the
Chandra X-ray Observatory and have multiband Subaru Suprime-Cam (BJ,
VJ, RC, IC, i+, z+) photometry from the Weighing the Giants
Survey (WtG; von der Linden et al. 2014MNRAS.439....2V 2014MNRAS.439....2V).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
allspecz.dat 110 1912 Catalogue of the 1912 reliable redshifts
acquired in this study
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Byte-by-byte Description of file: allspecz.dat
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Bytes Format Units Label Explanations
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1- 19 F19.15 deg RAdeg Right ascension (J2000)
21- 43 F23.19 deg DEdeg Declination (J2000)
45- 63 F19.15 mag Vmag Subaru V-band magnitude
65- 87 E23.16 --- z Spectroscopic redshift
89- 110 E22.16 --- e_z Error on z
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 07-Aug-2023