62,702 research outputs found
On the Correlations between Galaxy Properties and Supermassive Black Hole Mass
We use a large sample of upper limits and accurate estimates of supermassive
black holes masses coupled with libraries of host galaxy velocity dispersions,
rotational velocities and photometric parameters extracted from Sloan Digital
Sky Survey i-band images to establish correlations between the SMBH and host
galaxy parameters. We test whether the mass of the black hole, MBH, is
fundamentally driven by either local or global galaxy properties. We explore
correlations between MBH and stellar velocity dispersion sigma, bulge
luminosity, bulge mass Sersic index, bulge mean effective surface brightness,
luminosity of the galaxy, galaxy stellar mass, maximum circular velocity Vc,
galaxy dynamical and effective masses. We verify the tightness of the MBH-sigma
relation and find that correlations with other galaxy parameters do not yield
tighter trends. We do not find differences in the MBH-sigma relation of barred
and unbarred galaxies. The MBH-sigma relation of pseudo-bulges is also coarser
and has a different slope than that involving classical bulges. The MBH-bulge
mass is not as tight as the MBH-sigma relation, despite the bulge mass proving
to be a better proxy of MBH than bulge luminosity. We find a rather poor
correlation between MBH and Sersic index suggesting that MBH is not related to
the bulge light concentration. The correlations between MBH and galaxy
luminosity or mass are not a marked improvement over the MBH sigma relation. If
Vc is a proxy for the dark matter halo mass, the large scatter of the MBH-Vc
relation then suggests that MBH is more coupled to the baryonic rather than the
dark matter. We have tested the need for a third parameter in the MBH scaling
relations, through various linear correlations with bulge and galaxy
parameters, only to confirm that the fundamental plane of the SMBH is mainly
driven by sigma, with a small tilt due to the effective radius. (Abridged)Comment: 32 pages, 18 figures, 6 tables, accepted for publication in MNRA
Black hole scaling relations of active and quiescent galaxies: Addressing selection effects and constraining virial factors
Local samples of quiescent galaxies with dynamically measured black hole
masses (Mbh) may suffer from an angular resolution-related selection effect,
which could bias the observed scaling relations between Mbh and host galaxy
properties away from the intrinsic relations. In particular, previous work has
shown that the observed Mbh-Mstar (stellar mass) relation is more strongly
biased than the Mbh-sigma (velocity dispersion) relation. Local samples of
active galactic nuclei (AGN) do not suffer from this selection effect, as in
these samples Mbh is estimated from megamasers and/or reverberation
mapping-based techniques. With the exception of megamasers, Mbh-estimates in
these AGN samples are proportional to a virial coefficient fvir. Direct
modelling of the broad line region suggests that fvir~3.5. However, this
results in a Mbh-Mstar relation for AGN which lies below and is steeper than
the one observed for quiescent black hole samples. A similar though milder
trend is seen for the Mbh-sigma relation. Matching the high-mass end of the
Mbh-Mstar and Mbh-sigma relations observed in quiescent samples requires
fvir~15 and fvir~7, respectively. On the other hand, fvir~3.5 yields Mbh-sigma
and Mbh-Mstar relations for AGN which are remarkably consistent with the
expected `intrinsic' correlations for quiescent samples (i.e., once account has
been made of the angular resolution-related selection effect), providing
additional evidence that the sample of local quiescent black holes is biased.
We also show that, as is the case for quiescent black holes, the Mbh-Mstar
scaling relation of AGN is driven by velocity dispersion, thus providing
additional key constraints to black hole-galaxy co-evolution models.Comment: 15 pages, 5 Figures. MNRAS, accepte
Refining the M_BH-V_c scaling relation with HI rotation curves of water megamaser galaxies
Black hole - galaxy scaling relations provide information about the
coevolution of supermassive black holes and their host galaxies. We compare the
black hole mass - circular velocity (MBH - Vc) relation with the black hole
mass - bulge stellar velocity dispersion (MBH - sigma) relation, to see whether
the scaling relations can passively emerge from a large number of mergers, or
require a physical mechanism, such as feedback from an active nucleus. We
present VLA H I observations of five galaxies, including three water megamaser
galaxies, to measure the circular velocity. Using twenty-two galaxies with
dynamical MBH measurements and Vc measurements extending to large radius, our
best-fit MBH - Vc relation, log MBH = alpha + beta log(Vc /200 km s^-1), yields
alpha = 7.43+/-0.13, beta = 3.68+1.23/-1.20, and intrinsic scatter epsilon_int
= 0.51+0.11/-0.09. The intrinsic scatter may well be higher than 0.51, as we
take great care to ascribe conservatively large observational errors. We find
comparable scatter in the MBH - sigma relations, epsilon_int = 0.48+0.10/-0.08,
while pure merging scenarios would likely result in a tighter scaling with the
dark halo (as traced by Vc) than baryonic (sigma) properties. Instead, feedback
from the active nucleus may act on bulge scales to tighten the MBH - sigma
relation with respect to the MBH - Vc relation, as observed.Comment: 27 pages, 15 figures, ApJ accepte
The evolution of active galactic nuclei and their spins
Massive black holes (MBHs) in contrast to stellar mass black holes are
expected to substantially change their properties over their lifetime. MBH
masses increase by several order of magnitude over the Hubble time, as
illustrated by Soltan's argument. MBH spins also must evolve through the series
of accretion and mergers events that grow the MBH's masses. We present a simple
model that traces the joint evolution of MBH masses and spins across cosmic
time. Our model includes MBH-MBH mergers, merger-driven gas accretion,
stochastic fueling of MBHs through molecular cloud capture, and a basic
implementation of accretion of recycled gas. This approach aims at improving
the modeling of low-redshift MBHs and AGN, whose properties can be more easily
estimated observationally. Despite the simplicity of the model, it captures
well the global evolution of the MBH population from z\sim6 to today. Under our
assumptions, we find that the typical spin and radiative efficiency of MBHs
decrease with cosmic time because of the higher incidence of stochastic
processes in gas-rich galaxies and MBH-MBH mergers in gas-poor galaxies. At z=0
the spin distribution in gas-poor galaxies peaks at spins 0.4-0.8, and it is
not strongly mass dependent. MBHs in gas-rich galaxies have a more complex
evolution, with low-mass MBHs at low redshift having low spins, and spins
increasing at larger masses and redshifts. We also find that at z>1 MBH spins
are on average highest in high luminosity AGN, while at lower redshifts these
differences disappear.Comment: ApJ, in pres
Supermassive Black Holes and Their Host Galaxies - II. The correlation with near-infrared luminosity revisited
We present an investigation of the scaling relations between Supermassive
Black Hole (SMBH) masses (Mbh), and their host galaxies' K-band bulge (Lbul)
and total (Ltot) luminosities. The wide-field WIRCam imager at the
Canada-France-Hawaii-Telescope (CFHT) was used to obtain the deepest and
highest resolution near infrared images available for a sample of 35 galaxies
with securely measured Mbh, selected irrespective of Hubble type. For each
galaxy, we derive bulge and total magnitudes using a two-dimensional image
decomposition code that allows us to account, if necessary, for large- and
small-scale disks, cores, bars, nuclei, rings, envelopes and spiral arms. We
find that the present-day Mbh-Lbul and Mbh-Ltot relations have consistent
intrinsic scatter, suggesting that Mbh correlates equally well with bulge and
total luminosity of the host. Our analysis provides only mild evidence of a
decreased scatter if the fit is restricted to elliptical galaxies. The
log-slopes of the Mbh-Lbul and Mbh-Ltot relations are 0.75+/-0.10 and
0.92+/-0.14, respectively. However, while the slope of the Mbh-Lbul relation
depends on the detail of the image decomposition, the characterization of
Mbh-Ltot does not. Given the difficulties and ambiguities of decomposing galaxy
images into separate components, our results indicate that Ltot is more
suitable as a tracer of SMBH mass than Lbul, and that the Mbh-Ltot relation
should be used when studying the co-evolution of SMBHs and galaxies.Comment: 19 pages, 3 figures, 7 table
The Relation between Black Hole Mass, Bulge Mass, and Near-Infrared Luminosity
We present new accurate near-infrared (NIR) spheroid (bulge) structural
parameters obtained by two-dimensional image analysis for all galaxies with a
direct black hole (BH) mass determination. As expected, NIR bulge luminosities
Lbul and BH masses are tightly correlated, and if we consider only those
galaxies with secure BH mass measurement and accurate Lbul (27 objects), the
spread of MBH-Lbul is similar to MBH-sigma, where sigma is the effective
stellar velocity dispersion. We find an intrinsic rms scatter of ~0.3 dex in
log MBH. By combining the bulge effective radii R_e measured in our analysis
with sigma, we find a tight linear correlation (rms ~ 0.25 dex) between MBH and
the virial bulge mass (propto R_e sigma^2), with ~ 0.002. A partial
correlation analysis shows that MBH depends on both sigma and R_e, and that
both variables are necessary to drive the correlations between MBH and other
bulge properties.Comment: Astrophysical Journal Letters, in pres
Growing Massive Black Hole Pairs in Minor Mergers of Disk Galaxies
We perform a suite of high-resolution smoothed particle hydrodynamics
simulations to investigate the orbital decay and mass evolution of massive
black hole (MBH) pairs down to scales of ~30 pc during minor mergers of disk
galaxies. Our simulation set includes star formation and accretion onto the
MBHs, as well as feedback from both processes. We consider 1:10 merger events
starting at z~3, with MBH masses in the sensitivity window of the Laser
Interferometer Space Antenna, and we follow the coupling between the merger
dynamics and the evolution of the MBH mass ratio until the satellite galaxy is
tidally disrupted. While the more massive MBH accretes in most cases as if the
galaxy were in isolation, the satellite MBH may undergo distinct episodes of
enhanced accretion, owing to strong tidal torques acting on its host galaxy and
to orbital circularization inside the disk of the primary galaxy. As a
consequence, the initial 1:10 mass ratio of the MBHs changes by the time the
satellite is disrupted. Depending on the initial fraction of cold gas in the
galactic disks and the geometry of the encounter, the mass ratios of the MBH
pairs at the time of satellite disruption can stay unchanged or become as large
as 1:2. Remarkably, the efficiency of MBH orbital decay correlates with the
final mass ratio of the pair itself: MBH pairs that increase significantly
their mass ratio are also expected to inspiral more promptly down to
nuclear-scale separations. These findings indicate that the mass ratios of MBH
pairs in galactic nuclei do not necessarily trace the mass ratios of their
merging host galaxies, but are determined by the complex interplay between gas
accretion and merger dynamics.Comment: 5 pages, 4 figures, replaced to match accepted version on Ap
Gravitational recoil: effects on massive black hole occupation fraction over cosmic time
We assess the influence of massive black hole (MBH) ejections from galaxy
centres, due to the gravitational radiation recoil, along the cosmic merger
history of the MBH population. We discuss the 'danger' of the recoil for MBHs
as a function of different MBH spin/orbit configurations and of the host halo
cosmic bias, and on how that reflects on the 'occupation fraction' of MBHs. We
assess ejection probabilities for mergers occurring in a gas-poor environment,
where the MBH binary coalescence is driven by stellar dynamical processes, and
the spin/orbit configuration is expected to be isotropically distributed. We
contrast this case with the 'aligned' case. The latter is the most realistic
situation for 'wet', gas-rich mergers, which are the expectation for
high-redshift galaxies. We find that if all halos at z>5-7 host a MBH, the
probability of the Milky Way (or similar size galaxy) to host a MBH today is
less than 50%, unless MBHs form continuously in galaxies. The 'occupation
fraction' of MBHs, intimately related to halo bias and MBH formation
efficiency, plays a crucial role in increasing the retention fraction. Small
halos, with shallow potential wells and low escape velocities, have a high
ejection probability, but the MBH merger rate is very low along their galaxy
formation merger hierarchy: MBH formation processes are likely inefficient in
such shallow potential wells. Recoils can decrease the overall frequency of
MBHs in small galaxies to ~60%, while they have little effect on the frequency
of MBHs in large galaxies (at most a 20% effect).Comment: Accepted for publication in MNRA
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