On the nature of the z=0 X-ray absorbers: II. The contrast between local and AGN host galaxy absorption - AstrophysicsReport as inadecuate




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Abstract: We search for highly-ionized gas near three AGN host galaxies using theChandra low-energy transmission grating spectrograph. Strong absorption linesfrom such gas are seen at z=0, most likely from one or more of the followingcomponents: 1 a Galactic corona, 2 the Local Group medium, and 3 anextended warm-hot intergalactic medium WHIM filament passing through ourlocal overdensity. Since AGNs reside within host galaxies that are alsoexpected to sit within cosmically overdense regions, similar absorptionresulting from these three components should appear at the AGN redshifts aswell. However, no such absorption is seen. The lack of strong absorption linesis likely a result of the gas in these host galaxies and surrounding galaxyclusters being much hotter, and hence more highly ionized, than the gas in theLocal Group+Galaxy system. We conclude that WHIM filaments produce nomeasurable absorption lines at the AGN redshifts, and therefore contribute atmost a small fraction of the observed z=0 warm-hot gas.



Author: Rik J. Williams Leiden, Smita Mathur Ohio State, Fabrizio Nicastro OAR-INAF and CfA

Source: https://arxiv.org/







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