Radio properties of optically selected quasars

Eric J. Hooper, Chris D. Impey, Craig B. Foltz, Paul C. Hewett

Research output: Contribution to journalArticlepeer-review

81 Scopus citations


Approximately one-quarter (256 objects) of the Large Bright Quasar Survey (LBQS) has been observed with the VLA at 8.4 GHz, resulting in 44 detections (17%) with a median 3 σ noise limit of 0.29 mJy. Quasars with radio luminosity detectable at this limit are underrepresented at faint absolute blue magnitudes (MB ≥ -24), an effect which cannot be explained by a potential LBQS selection bias against quasars which have large radio luminosities and small optical luminosities. The radio-loud (8 GHz luminosity > 1025 W Hz-1) fraction is observed to change as a function of redshift and MB, for MB < -24, although the causal variable is ambiguous. The description most consistent with the available data is that radio-loud fraction is approximately constant over the range -27.5 ≲ MB ≲ -24 and increases at brighter absolute magnitudes. The radio-loud fraction as a function of redshift reaches a local maximum at z ≈ 1, and, aside from the effects of increased radio-loud fraction at bright MB, remains roughly constant to redshifts approaching 5. The log R8.4 distribution (radio-to-optical luminosity ratio) of the current LBQS sample may be bimodal, but the results of statistical tests are ambiguous, requiring a larger sample size to become definite.

Original languageEnglish (US)
Pages (from-to)62-79
Number of pages18
JournalAstrophysical Journal
Issue number1
StatePublished - May 20 1995


  • Quasars: general
  • Radio continuum: galaxies
  • Surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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