90 research outputs found
The Luminosity Function of QSO Host Galaxies
We present some results from our HST archival image study of 71 QSO host
galaxies. The objects are selected to have z < 0.46 and total absolute
magnitude M_V < -23 (H_0=50 km/s/Mpc). This initial study investigates host
morphology and radio loudness, and it derives the QSO host galaxy luminosity
function. We have analyzed available WFPC2 broad band images, using a uniform
set of procedures. The host galaxies span a narrow range of luminosities and
are exceptionally bright, much more so than normal galaxies, usually L > L*_V.
The QSOs are almost equally divided among radio-loud QSOs with elliptical
hosts, radio-quiet QSOs with elliptical hosts, and radio-quiet QSOs with spiral
hosts. Using a weighting procedure, we derive the combined luminosity function
of QSO host galaxies. We find that the luminosity function of QSO hosts differs
in shape from that of normal galaxies but that they coincide at the highest
luminosities. The ratio of the number of quasar hosts to the number of normal
galaxies at a luminosity L_V is R = [L_V/(11.48 L*_V)]^2.46, where L*_V
corresponds to M*_V = -22.35, and a QSO is defined to be an object with total
nuclear plus host light M_V < -23. This ratio can be interpreted as the
probability that a galaxy with luminosity L_V will host a QSO at redshift z ~
0.26. (Abridged)Comment: 36 pages, 11 figures, LaTeX. Expanded analysis and additional
figures. To be published in the Astrophysical Journal, v576, September 1,
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