Jim Condon (NRAO)

Radio Emission from Optically Selected QSOs - Jim Condon Colloquium

ATNF Marsfield Lecture Theatre

Abstract

The first quasar (quasi-stellar radio source) was identified at Parkes
almost 50 years ago because it is a very strong radio source,
comparable with the most luminous radio galaxies. Although optically
selected quasi-stellar objects (QSOs) are generally similar to
quasars, their radio sources are typically several orders of magnitude
fainter and most have never been detected, leading to decades-long
unresolved debates about the nature of the radio emission from
radio-quiet QSOs and whether QSOs reside in elliptical or spiral
galaxies. Sensitive new statistical observations using NVSS data at
1.4 GHz and direct observations with the EVLA at 6 GHz have finally
detected nearly all QSOs in two large volume-limited samples of
low-redshift SDSS QSOs. The resulting radio luminosity functions and
spectral indices strongly suggest that (1) both AGNs and starbursts
contribute to their radio emission in ways that make the QSOs look
remarkably similar to luminous nearby galaxies and (2) QSOs reside in
a mixture of star-forming spiral galaxies and "red and dead"
elliptical galaxies.