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Sloan Digital Sky Survey/XMM-Newton Type1 AGN X-Ray and Radio Properties Catalog

Metadata Updated: September 19, 2025

X-ray emission from active galactic nuclei (AGN) is dominated by the accretion disk around a supermassive black hole. The radio luminosity, however, has not such a clear origin except in the most powerful sources where jets are evident. The origin (and even the very existence) of the local bi-modal distribution in radio-loudness is also a debated issue. By analyzing X-ray, optical and radio properties of a large sample of type 1 AGN and quasars (QSOs) up to z > 2, where the bulk of this population resides, the authors aim to explore the interplay between radio and X-ray emission in AGN, in order to further our knowledge on the origin of radio emission, and its relation to accretion. They analyze a large (~800 sources) sample of type 1 AGN and QSOs selected from the 2XMMi XMM-Newton X-ray source catalog, cross-correlated with the SDSS DR7 spectroscopic catalog, covering a redshift range from z ~ 0.3 to z ~ 2.3. Supermassive black hole masses are estimated from the Mg II emission line, bolometric luminosities from the X-ray data, and radio emission or upper limits from the FIRST catalog. Most of the sources accrete close to the Eddington limit and the distribution in radio-loudness does not appear to have a bi-modal behavior. This study confirms that radio-loud AGN are also X-ray loud, with an X-ray-to-optical ratio up to twice that of radio-quiet objects, even excluding the most extreme strongly jetted sources. By analyzing complementary radio-selected control samples, the authors find evidence that these conclusions are not an effect of the X-ray selection, but are likely a property of the dominant QSO population. The authors of this catalog conclude that their findings are best interpreted in a context where radio emission in AGN, with the exception of a minority of beamed sources, arises from very close to the accretion disk and is therefore heavily linked to X-ray emission. They also speculate that the radio-loud/radio-quiet dichotomy might either be an evolutionary effect that developed well after the QSO peak epoch, or an effect of incompleteness in small samples. Basic information and derived properties are presented for the sample of X-ray selected type 1 AGN (as well as for the 11 X-ray undetected type 1 AGN in the "control sample"): coordinates, redshift, X-ray and radio fluxes, optical magnitudes, from the SDSS, 2XMMi, and FIRST catalogs; continuum luminosities at 3000 Angstroms and in the X-ray band, black hole masses, bolometric luminosities, Eddington ratios; for the sources falling in the FIRST field, optical fluxes at 2500 and 4400 Angstroms, X-ray-to-optical index, radio classification, and the ratios between the radio and the UV, optical, and X-ray fluxes. This table was created by the HEASARC in October 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/545/A66">CDS Catalog J/A+A/545/A66</a> files table3.dat, table4.dat and table5.dat. This is a service provided by NASA HEASARC .

Access & Use Information

Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Dates

Metadata Created Date April 11, 2025
Metadata Updated Date September 19, 2025

Metadata Source

Harvested from NASA Data.json

Additional Metadata

Resource Type Dataset
Metadata Created Date April 11, 2025
Metadata Updated Date September 19, 2025
Publisher High Energy Astrophysics Science Archive Research Center
Maintainer
Identifier ivo://nasa.heasarc/agnsdssxm2
Data Last Modified 2025-09-10
Category Astrophysics
Public Access Level public
Bureau Code 026:00
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id 9cd54784-a532-4348-9357-1c26a6e08d08
Harvest Source Id 58f92550-7a01-4f00-b1b2-8dc953bd598f
Harvest Source Title NASA Data.json
Homepage URL https://heasarc.gsfc.nasa.gov/W3Browse/all/agnsdssxm2.html
Program Code 026:000
Source Datajson Identifier True
Source Hash 6ba08660b19bb40f74491b9778c7460d45d6a62ef916a3bdf1404e88c67a0e87
Source Schema Version 1.1

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