The X-ray properties of high-z FRI candidates in the COSMOS field

Abstract

We report the X-ray analysis of a sample of candidate high-redshift (1<z<2) FRI sources from the sample of Chiaberge et al. (2009), observed in the Chandra COSMOS field (C-COSMOS). Our main goals are to study their nuclear properties by means of unresolved X-ray emission, and to constrain the presence of clusters surrounding the FRI sources from the diffuse X-ray emission by the associated hot plasma. Among 19 FRI candidates, 6 have an X-ray unresolved counterpart in the C-COSMOS catalog. Two additional sources are not present in the C-COSMOS catalog but are clearly detected in the Chandra images. X-ray spectral analysis, when possible, or hardness ratio of the stacked emission from X-ray detected sources, suggest that some of them have significant intrinsic absorption (N_H~10^22 cm^-2), and high X-ray luminosities with respect to local FRIs. From the stacking analysis of the 11 non-detected sources, however, we find evidence for unresolved soft X-ray emission and no detected hard emission, suggesting an unabsorbed spectrum. Therefore, the X-ray properties vary significantly from source to source among these FRI candidates. From the analysis of the stacked images of all 19 FRI candidates we can rule out the presence of virialized haloes with temperatures larger than 2-3 keV; however, the upper limit on the average extended emission is still consistent with the presence of ~1-2 keV hot gas.

11 pages, 5 figures, MNRAS accepted; added co-author affiliation

References in corpus (18)

• COSMOS Photometric Redshifts with 30-bands for 2-deg2
• zCOSMOS: A Large VLT/VIMOS redshift survey covering 0 < z < 3 in the COSMOS field
• The Chandra Deep Field-South Survey: 4 Ms Source Catalogs
• The Chandra COSMOS Survey, I: Overview and Point Source Catalog
• X-ray spectral properties of AGN in the Chandra Deep Field South
• The XMM-Newton wide-field survey in the COSMOS field: I. Survey description
• On the prevalence of radio-loud AGN in brightest cluster galaxies: implications for AGN heating of cooling flows
• The VLA-COSMOS Survey: II. Source Catalog of the Large Project
• The XMM-Newton wide-field survey in the COSMOS field. The point-like X-ray source catalogue
• Searching for Cool Core Clusters at High redshift
• Large Structures and Galaxy Evolution in COSMOS at z < 1.1
• The accretion mechanism in low-power radio galaxies
• Magellan Spectroscopy of AGN Candidates in the COSMOS Field
• Radiative pressure feedback by a quasar in a galactic bulge
• The XMM-LSS Survey: A well controlled X-ray cluster sample over the D1 CFHTLS area
• ChaMP Serendipitous Galaxy Cluster Survey
• Red sequence determination of the redshift of the cluster of galaxies JKCS041: z~2.2
• Bulges and disks in the Host Galaxies of low redshift 3CR Sources: a near-IR view of their radial brightness profile

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• X-ray spectral analyses of AGNs from the 7Ms Chandra Deep Field-South survey: the distribution, variability, and evolution of AGN's obscuration
• Cluster candidates around low power radio-galaxies at z~1-2 in COSMOS
• Spectral Energy Distributions of low-luminosity radio galaxies at z~1-3: a high-z view of the host/AGN connection
• A new method to search for high redshift clusters using photometric redshifts