Multiwavelength selection of obscured agn and contributions to the X-ray background

dc.contributorByrd, Gene G.
dc.contributorCrenshaw, Daniel Michael
dc.contributorIrwin, Jimmy A.
dc.contributorVisscher, Pieter B.
dc.contributorWhite, Raymond E.
dc.contributor.advisorKeel, W. C.
dc.contributor.authorMay, Branyon
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.descriptionElectronic Thesis or Dissertationen_US
dc.description.abstractObscuration in AGN is a crucial component to understanding the observed spectrum of the X-ray Background. We tested numerous AGN selection techniques in X-ray, mid-infrared, and optical to test for multiwavelength correlations and to help establish selection criteria for obscured AGN. With AGN sources dominating background X-ray sources, we selected medium-depth archival Chandra observations covering 5.6 deg^2 of sky and generating a large sample of serendipitous X-ray sources (greater than 10,000). The mid-infrared component came from archival Spitzer data, with ~3,500 sources being detected in at least two IRAC bands and 1,485 in all 4 bands. For the optical component, greater than 70% of the Chandra observations also had full coverage within the SDSS Data Release 7, >2,300 optical counterparts and 125 spectra. In analyzing the sample, we have identified the parameter spaces in the X-ray/mid-infrared/optical that are optimized for containing members of the elusive class of obscured AGN, and provide a candidate list. We cross-check our X-ray number counts and source densities with contributions to the X-ray background, and find that we resolve approximately 90% of the X-ray Background in the 0.5-8.0 keV range. Testing populations divided on X-ray hardness and flux-level confirms that the unresolved hard X-ray background will be dominated by large populations of increasingly fainter and harder sources.en_US
dc.format.extent96 p.
dc.publisherUniversity of Alabama Libraries
dc.relation.hasversionborn digital
dc.relation.ispartofThe University of Alabama Electronic Theses and Dissertations
dc.relation.ispartofThe University of Alabama Libraries Digital Collections
dc.rightsAll rights reserved by the author unless otherwise indicated.en_US
dc.titleMultiwavelength selection of obscured agn and contributions to the X-ray backgrounden_US
dc.typetext of Alabama. Department of Physics and Astronomy University of Alabama
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