VLA 6-GHz Observations of Low-Redshift SDSS QSOs

This table contains results from 6-GHz Jansky Very Large Array (JVLA) observations covering a volume-limited sample of 178 low-redshift (0.2 &lt; z &lt;0.3) optically selected quasi-stellar objects (QSOs). These 176 radio detections fall into two clear categories: (1) about 20% are radio-loud QSOs (RLQs) with spectral luminosities of L&lt;sub&gt;6&lt;/sub&gt; &gt;~ 10&lt;sup&gt;23.2&lt;/sup&gt; W/Hz that are primarily generated in the active galactic nucleus (AGN) responsible for the excess optical luminosity that defines a bona fide QSO; and (2) the remaining 80% that are radio-quiet QSOs (RQQs) that have 10&lt;sup&gt;21&lt;/sup&gt; &lt;~ L&lt;sub&gt;6&lt;/sub&gt; &lt;~ 10&lt;sup&gt;23.2&lt;/sup&gt; W/Hz and radio sizes &lt;~ 10 kpc, and the authors suggest that the bulk of their radio emission is powered by star formation in their host galaxies. &quot;Radio-silent&quot; QSOs (L_6_&lt;~ 10&lt;sup&gt;21&lt;/sup&gt; W/Hz) are rare, so most RQQ host galaxies form stars faster than the Milky Way; they are not &quot;red and dead&quot; ellipticals. Earlier radio observations did not have the luminosity sensitivity of L&lt;sub&gt;6&lt;/sub&gt; &lt;~ 10&lt;sup&gt;21&lt;/sup&gt; W/Hz that is needed to distinguish between such RLQs and RQQs. Strong, generally double-sided radio emission spanning &gt;&gt; 10 kpc was found to be associated with 13 of the 18 RLQ cores with peak flux densities of S&lt;sub&gt;p&lt;/sub&gt; &gt; 5 mJy/beam (log(L) &gt;~ 24). The radio luminosity function of optically selected QSOs and the extended radio emission associated with RLQs are both inconsistent with simple &quot;unified&quot; models that invoke relativistic beaming from randomly oriented QSOs to explain the difference between RLQs and RQQs. Some intrinsic property of the AGN or their host galaxies must also determine whether or not a QSO appears radio-loud. The authors have reprocessed the VLA observations of a sample of SDSS QSOs discussed in Kimball et al. (2011, ApJ, 739, L29). These were obtained using the VLA C configuration with a central frequency of 6 GHz and a bandwidth of 2 GHz in each of the two circular polarizations: with natural weighting the synthesized beam width was 3.5 arcseconds FWHM. The authors generated a catalog of radio sources associated with each QSO. They detected radio emission at 6 GHz from all but two of the 178 color-selected SDSS QSOs contained in this volume-limited sample of QSOs more luminous than M&lt;sub&gt;i&lt;/sub&gt; = -23 and with redshifts 0.2 &lt; z &lt; 0.3. All calculations in the reference paper assume a flat LambdaCDM 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; and Omega&lt;sub&gt;Lambda&lt;/sub&gt; = 0.7. Spectral luminosities are specified by their source-frame frequencies, flux densities are specified in the observer&#39;s frame, and a mean spectral index of alpha = d(log S)/d(log nu) = -0.7 is used to make frequency conversions This table was created by the HEASARC in April 2017 based upon the &lt;a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/831/168"&gt;CDS Catalog J/ApJ/831/168&lt;/a&gt; file table1.dat. This is a service provided by NASA HEASARC .

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Organization: National Aeronautics and Space Administration