arXiv subjects

Marcella Brusa

Publications and source records attributed to Marcella Brusa.

93 records · Page 6Linked to original sources

arXiv2004

Are QSO2 hiding among EROs?

We present the results of a deep (80 ks) XMM-Newton survey of one of the largest sample of near-infrared selected Extremely Red Objects (R-K>5) available to date (~300 objects, Daddi et al. 2000). The fraction of individually detected, X-ray emitting EROs is of the order of ~3.5%, down to F_x > 4x10^-15 cgs and Ks<19.2. In order to derive the X-ray intrinsic properties of AGN EROs and to place our findings in a broader context, we have also considered all the X-ray detected EROs available in the literature. The X-ray, optical, and near-infrared properties of those X-ray selected EROs with a spectroscopic or photometric redshift nicely match those expected for quasars 2, the high-luminosity, high-redshift obscured AGNs predicted in XRB synthesis models.

astro-ph↗

arXiv2004

A broad iron K alpha line at z=1.146

We report the discovery of a strong iron K alpha line in the hard X-ray selected source CXOJ 123716.7+621733 in the Chandra Deep Field North survey at z=1.146. The analysis is made possible by the very deep exposure ~2 Ms and low background of the ACIS detector. The line profile seems to be inconsistent with a narrow feature. The best fit solution is achieved with a broad line. Most of the flux in the broad component originates at energies below 6.4 keV with a shape similar to that expected from emission in the innermost regions of the accretion disk.

astro-ph↗

arXiv2002

Hard X-ray observations of Extremely Red Objects

Extremely Red Objects (EROs, R-K>5) constitute a heterogenous class of extragalactic sources including high redshift elliptical galaxies, dusty star-forming systems and heavily obscured AGNs. Hard X-ray observations provide an unique and powerful tool to uncover obscured nuclear or star-forming activity. We present the results of XMM-Newton observations of the largest sample of EROs available to date (about 450 objects over a contiguous area of 700 arcmin^2). Five of the 46 hard X-ray selected sources brighter than 3x10^{-15} cgs in the 2-10 keV band, are associated with EROs. All of the X-ray detected EROs show rather extreme X-ray-to-optical flux ratios, suggesting the presence of highly obscured AGN activity. We also report on the X-ray stacking analysis of spectroscopically identified EROs in the Chandra Deep Field South.

astro-ph↗