{
  "@type": "dcat:Dataset",
  "accessLevel": "public",
  "bureauCode": [
    "026:00"
  ],
  "contactPoint": {
    "@type": "vcard:Contact",
    "fn": "HEASARC Help Desk",
    "hasEmail": "mailto:andrew.ptak@nasa.gov"
  },
  "description": "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 .",
  "distribution": [
    {
      "@type": "dcat:Distribution",
      "downloadURL": "https://heasarc.gsfc.nasa.gov/W3Browse/all/osrilqxray.html",
      "format": "HTML",
      "mediaType": "text/html"
    },
    {
      "@type": "dcat:Distribution",
      "downloadURL": "https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=osrilqxray&",
      "format": "BIN",
      "mediaType": "application/octet-stream"
    }
  ],
  "identifier": "ivo://nasa.heasarc/osrilqxray",
  "keyword": [
    "__"
  ],
  "landingPage": "ivo://nasa.heasarc/osrilqxray",
  "license": "https://www.usa.gov/government-works",
  "modified": "2026-09-07",
  "programCode": [
    "026:000"
  ],
  "publisher": {
    "@type": "org:Organization",
    "name": "High Energy Astrophysics Science Archive Research Center"
  },
  "theme": [
    "Astrophysics"
  ],
  "title": "Optically Selected Radio-Intermediate and Loud Quasars X-ray Emission Catalog"
}