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Table · dataset · 2026

Chandra Serendipitous Extragalactic X-Ray Source ID (SEXSI)/Spitzer AGN Catalog

Listed in IVOA Registry (Virtual Observatory)

The authors compare the relative merits of active galactic nuclei (AGN) selection at X-ray and mid-infrared wavelengths using data from moderately deep fields observed by both Chandra and Spitzer.

Description

The X-ray-selected AGN sample and associated photometric and spectroscopic optical follow-up are drawn from a subset of fields studied as part of the Serendipitous Extragalactic X-ray Source Identification (SEXSI) program. Mid-infrared data in these fields are derived from targeted and archival Spitzer imaging, and mid-infrared AGN selection is accomplished primarily through application of the Infrared Array Camera (IRAC) color-color AGN "wedge" selection technique.

Nearly all X-ray sources in these fields which exhibit clear spectroscopic signatures of AGN activity have mid-infrared colors consistent with IRAC AGN selection. These are predominantly the most luminous X-ray sources. X-ray sources that lack high-ionization and/or broad lines in their optical spectra are far less likely to be selected as AGNs by mid-infrared color selection techniques.

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The fraction of X-ray sources identified as AGN in the mid-infrared increases monotonically as the X-ray luminosity increases. Conversely, only 22% of mid-infrared-selected AGN are detected at X-ray energies in the moderately deep (t_exp_n~ 100 ks) SEXSI Chandra data. The authors have expanded the multi-wavelength data available for six SEXSI fields by obtaining Spitzer imaging observations.

All six fields have deep Chandra X-ray images, optical imaging, and extensive, deep optical spectroscopy -- all of which has been published in Harrison et al. (2003, ApJ, 596, 944), Eckart et al. (2005, ApJS, 156, 35), and Eckart et al. (2006, ApJS, 165, 19). The authors obtained mid-infrared imaging through both archival and targeted Spitzer programs which include imaging at 3.6, 4.5, 5.8, and 8 micron (µm) from IRAC (PID 00017, 00064, 20694 and 20808), and imaging at 24 um from MIPS (PID 20808 and 00083).

This table contains mid-IR photometric data for 290 hard X-ray-selected SEXSI sources. Each of the four IRAC catalogs as well as the MIPS catalog was individually matched to the SEXSI X-ray source positions using a 2.5 arcseconds search radius. To calculate a false match rate, the authors shifted the X-ray source catalog by 1' and matched to the IRAC and MIPS catalogs; this entire procedure was repeated 6 times using different 1' shifts.

The resulting false match rates were 10.1% (3.6 um), 7.2% (4.5 um), 3.7% (5.8 um), 2.6% (8.0 um), 1% (24 um), and <1% for four-band-detected IRAC sources. This table was created by the HEASARC in Match 2012 based on <a href="cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/708/584">CDS Catalog J/ApJ/708/584</a> file table2.dat. This is a service provided by NASA HEASARC .

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Stated by source
Infrared · X-Ray
Inferred from text
Astronomical sciences 74% · Image 65% · Imaging 75% · Tabular 65%
Provenance · 1 source records, 12 field assertions
SourceKeyLast seenRaw
IVOA Registry (Virtual Observatory)ivo://nasa.heasarc/chansexagn7 d agoJSON v1
FieldAssertionExtractorEvidence
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concepts[field].anzsrc:group:5101enrichment · IVOA Registrytaxonomy-embedding@1.1.0title+keywords+description (74%)
concepts[field].local:field:astronomymapping · IVOA Registryconnector:ivoa_registry@1.0.0
concepts[modality].ivoa_waveband:infraredsource · IVOA Registryconnector:ivoa_registry@1.0.0
concepts[modality].ivoa_waveband:x-raysource · IVOA Registryconnector:ivoa_registry@1.0.0
concepts[modality].local:modality:imageenrichment · IVOA Registrykeyword-concept-rules@1.0.0title+description (65%)
concepts[modality].local:modality:imagingenrichment · IVOA Registrykeyword-concept-rules@1.0.0title+description (75%)
concepts[modality].local:modality:tabularenrichment · IVOA Registrykeyword-concept-rules@1.0.0title+description (65%)
descriptionsource · IVOA Registryconnector:ivoa_registry@1.0.0rr.resource.res_description
publication_datesource · IVOA Registryconnector:ivoa_registry@1.0.0
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updated_datesource · IVOA Registryconnector:ivoa_registry@1.0.0