TY - JOUR
T1 - The host galaxies of luminous quasars
AU - Floyd, David J. E.
AU - Kukula, Marek J.
AU - Dunlop, James S.
AU - McLure, Ross J.
AU - Miller, Lance
AU - Percival, Will J.
AU - Baum, Stefi A.
AU - O'Dea, Christopher P.
PY - 2004/11/1
Y1 - 2004/11/1
N2 - We present the results of a deep Hubble Space Telescope (HST)/Wide Field
and Planetary Camera 2 imaging study of 17 quasars at z~= 0.4, designed
to determine the properties of their host galaxies. The sample consists
of quasars with absolute magnitudes in the range -24
>=MV>=- 28, allowing us to investigate host galaxy
properties across a decade in quasar luminosity, but at a single
redshift. Our previous imaging studies of active galactic nuclei hosts
have focused primarily on quasars of moderate luminosity, but the most
powerful objects in the current sample have powers comparable to the
most luminous quasars found at high redshifts.
We find that the host galaxies of all the radio-loud quasars, and all
the radio-quiet quasars in our sample with nuclear luminosities
MV <-24, are massive bulge-dominated galaxies, confirming
and extending the trends deduced from our previous studies. From the
best-fitting model host galaxies we have estimated spheroid and hence
black hole (BH) masses, and the efficiency (with respect to the
Eddington luminosity) with which each quasar emits radiation. The
largest inferred black hole mass in our sample is MBH~= 3
× 109 Msolar, comparable to the mass of the
black holes at the centres of M87 and Cygnus A. We find no evidence for
super-Eddington accretion rates in even the most luminous objects (0.05
<L/LEdd <1.0).
We investigate the role of scatter in the black hole-spheroid mass
relation in determining the ratio of quasar to host-galaxy luminosity,
by generating simulated populations of quasars lying in hosts with a
Schechter mass function. Within the subsample of the highest-luminosity
quasars, the observed variation in nuclear-host luminosity ratio is
consistent with being the result of the scatter in the black
hole-spheroid relation. Quasars with high nuclear-host luminosity ratios
can be explained in terms of sub-Eddington accretion rates on to black
holes in the high-mass tail of the black hole-spheroid relation. Our
results imply that, owing to the Schechter function cut-off, host mass
should not continue to increase linearly with quasar luminosity, at the
very highest luminosities. Any quasars more luminous than
MV=-27 should be found in massive elliptical hosts, which at
the present day would have MV~=-24.5.
AB - We present the results of a deep Hubble Space Telescope (HST)/Wide Field
and Planetary Camera 2 imaging study of 17 quasars at z~= 0.4, designed
to determine the properties of their host galaxies. The sample consists
of quasars with absolute magnitudes in the range -24
>=MV>=- 28, allowing us to investigate host galaxy
properties across a decade in quasar luminosity, but at a single
redshift. Our previous imaging studies of active galactic nuclei hosts
have focused primarily on quasars of moderate luminosity, but the most
powerful objects in the current sample have powers comparable to the
most luminous quasars found at high redshifts.
We find that the host galaxies of all the radio-loud quasars, and all
the radio-quiet quasars in our sample with nuclear luminosities
MV <-24, are massive bulge-dominated galaxies, confirming
and extending the trends deduced from our previous studies. From the
best-fitting model host galaxies we have estimated spheroid and hence
black hole (BH) masses, and the efficiency (with respect to the
Eddington luminosity) with which each quasar emits radiation. The
largest inferred black hole mass in our sample is MBH~= 3
× 109 Msolar, comparable to the mass of the
black holes at the centres of M87 and Cygnus A. We find no evidence for
super-Eddington accretion rates in even the most luminous objects (0.05
<L/LEdd <1.0).
We investigate the role of scatter in the black hole-spheroid mass
relation in determining the ratio of quasar to host-galaxy luminosity,
by generating simulated populations of quasars lying in hosts with a
Schechter mass function. Within the subsample of the highest-luminosity
quasars, the observed variation in nuclear-host luminosity ratio is
consistent with being the result of the scatter in the black
hole-spheroid relation. Quasars with high nuclear-host luminosity ratios
can be explained in terms of sub-Eddington accretion rates on to black
holes in the high-mass tail of the black hole-spheroid relation. Our
results imply that, owing to the Schechter function cut-off, host mass
should not continue to increase linearly with quasar luminosity, at the
very highest luminosities. Any quasars more luminous than
MV=-27 should be found in massive elliptical hosts, which at
the present day would have MV~=-24.5.
U2 - 10.1111/j.1365-2966.2004.08315.x
DO - 10.1111/j.1365-2966.2004.08315.x
M3 - Article
VL - 355
SP - 196
EP - 220
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
ER -