Optically Selected Radio-Intermediate and Loud Quasars X-ray Emission Catalog

This catalog contains some of the results of an investigation into the X-ray properties of radio-intermediate and radio-loud quasars (RIQs and RLQs, respectively). The authors have combined large, modern optical (e.g., SDSS) and radio (e.g., FIRST) surveys with archival X-ray data from Chandra, XMM-Newton, and ROSAT to generate an optically selected sample that includes 188 RIQs and 603 RLQs. This sample is constructed independently of X-ray properties but has a high X-ray detection rate (85%); it provides broad and dense coverage of the luminosity-redshift (l-z) plane, including at high redshifts (22% of the objects have z = 2-5), and it extends to high radio-loudness R<sub>L</sub> values (33% of objects have R<sub>L</sub> = log(L<sub>r</sub>/L<sub>o</sub>) = 3 - 5), where L<sub>r</sub> and L<sub>o</sub> are the rest-frame monochromatic luminosities at 5 GHz and 2500 Angstroms, respectively). The authors measure the "excess" X-ray luminosity of RIQs and RLQs relative to radio-quiet quasars (RQQs) as a function of radio loudness and luminosity, and parametrize the X-ray luminosity of RIQs and RLQs both as a function of optical/UV luminosity and also as a joint function of optical/UV and radio luminosity. RIQs are only modestly X-ray bright relative to RQQs; it is only at high values of radio loudness (R<sub>L</sub> >~ 3.5) and radio luminosity that RLQs become strongly X-ray bright. This HEASARC table contains the primary sample from the reference paper. The authors consider three categories of quasars in this work: RQQs, RIQs, and RLQs (rather than just RQQs and RLQs), where the define RIQs to consist of objects with 1 <= R<sub>L</sub> < 2; consequently, the objects they classify as RLQs satisfy R<sub>L</sub> >= 2. The primary sample contained herein consists of 654 optically selected RIQs and RLQs with SDSS/FIRST observations and high-quality X-ray coverage from Chandra (171), XMM-Newton (202), or ROSAT (281). The primary sample is split nearly evenly between spectroscopic (312) and high-confidence photometric (342) quasars. Most (562) of the primary sample objects possess serendipitous off-axis X-ray coverage, while the remainder (92) were targeted in the observations used in this sample. The X-ray detection fraction for the primary sample is 84%; the detection fraction for those objects with Chandra/XMM-Newton/ROSAT coverage is 95%/92%/70% (typical ROSAT observations are comparatively less sensitive and have higher background). The authors adopt a standard cosmology with H<sub>0</sub> = 70 km s<sup>-1</sup> Mpc<sup>-1</sup>, Omega<sub>M</sub> = 0.3, and Omega<sub>Lambda</sub> = 0.7 throughout their study. This table was created by the HEASARC in October 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/726/20">CDS Catalog J/ApJ/726/20</a> file table1.dat. This is a service provided by NASA HEASARC .

Data and Resources

Field Value
accessLevel public
bureauCode {026:00}
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catalog_describedBy https://project-open-data.cio.gov/v1.1/schema/catalog.json
identifier ivo://nasa.heasarc/osrilqxray
landingPage https://heasarc.gsfc.nasa.gov/W3Browse/all/osrilqxray.html
modified 2025-09-10
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publisher High Energy Astrophysics Science Archive Research Center
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license_id notspecified
license_title License not specified
maintainer Tess Jaffe
maintainer_email tess.jaffe@nasa.gov
metadata_created 2025-09-23T15:57:43.069966
metadata_modified 2025-09-23T15:57:43.069972
notes This catalog contains some of the results of an investigation into the X-ray properties of radio-intermediate and radio-loud quasars (RIQs and RLQs, respectively). The authors have combined large, modern optical (e.g., SDSS) and radio (e.g., FIRST) surveys with archival X-ray data from Chandra, XMM-Newton, and ROSAT to generate an optically selected sample that includes 188 RIQs and 603 RLQs. This sample is constructed independently of X-ray properties but has a high X-ray detection rate (85%); it provides broad and dense coverage of the luminosity-redshift (l-z) plane, including at high redshifts (22% of the objects have z = 2-5), and it extends to high radio-loudness R&lt;sub&gt;L&lt;/sub&gt; values (33% of objects have R&lt;sub&gt;L&lt;/sub&gt; = log(L&lt;sub&gt;r&lt;/sub&gt;/L&lt;sub&gt;o&lt;/sub&gt;) = 3 - 5), where L&lt;sub&gt;r&lt;/sub&gt; and L&lt;sub&gt;o&lt;/sub&gt; are the rest-frame monochromatic luminosities at 5 GHz and 2500 Angstroms, respectively). The authors measure the &quot;excess&quot; X-ray luminosity of RIQs and RLQs relative to radio-quiet quasars (RQQs) as a function of radio loudness and luminosity, and parametrize the X-ray luminosity of RIQs and RLQs both as a function of optical/UV luminosity and also as a joint function of optical/UV and radio luminosity. RIQs are only modestly X-ray bright relative to RQQs; it is only at high values of radio loudness (R&lt;sub&gt;L&lt;/sub&gt; &gt;~ 3.5) and radio luminosity that RLQs become strongly X-ray bright. This HEASARC table contains the primary sample from the reference paper. The authors consider three categories of quasars in this work: RQQs, RIQs, and RLQs (rather than just RQQs and RLQs), where the define RIQs to consist of objects with 1 &lt;= R&lt;sub&gt;L&lt;/sub&gt; &lt; 2; consequently, the objects they classify as RLQs satisfy R&lt;sub&gt;L&lt;/sub&gt; &gt;= 2. The primary sample contained herein consists of 654 optically selected RIQs and RLQs with SDSS/FIRST observations and high-quality X-ray coverage from Chandra (171), XMM-Newton (202), or ROSAT (281). The primary sample is split nearly evenly between spectroscopic (312) and high-confidence photometric (342) quasars. Most (562) of the primary sample objects possess serendipitous off-axis X-ray coverage, while the remainder (92) were targeted in the observations used in this sample. The X-ray detection fraction for the primary sample is 84%; the detection fraction for those objects with Chandra/XMM-Newton/ROSAT coverage is 95%/92%/70% (typical ROSAT observations are comparatively less sensitive and have higher background). The authors adopt a standard cosmology with H&lt;sub&gt;0&lt;/sub&gt; = 70 km s&lt;sup&gt;-1&lt;/sup&gt; Mpc&lt;sup&gt;-1&lt;/sup&gt;, Omega&lt;sub&gt;M&lt;/sub&gt; = 0.3, and Omega&lt;sub&gt;Lambda&lt;/sub&gt; = 0.7 throughout their study. This table was created by the HEASARC in October 2012 based on &lt;a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/726/20"&gt;CDS Catalog J/ApJ/726/20&lt;/a&gt; file table1.dat. This is a service provided by NASA HEASARC .
num_resources 2
num_tags 9
title Optically Selected Radio-Intermediate and Loud Quasars X-ray Emission Catalog