83 research outputs found
The Impact of Black Hole Scaling Relation Assumptions on the Mass Density of Black Holes
We examine the effect of supermassive black hole (SMBH) mass scaling relation
choice on the inferred SMBH mass population since redshift . To make
robust predictions for the gravitational wave background (GWB) we must have a
solid understanding of the underlying SMBH demographics. Using the SDSS and 3D
HST+CANDELS surveys for we evaluate the inferred SMBH masses from
two SMBH-galaxy scaling relations: - and
-. Our SMBH mass functions come directly from stellar
mass measurements for -, and indirectly
from stellar mass and galaxy radius measurements along with the galaxy mass
fundamental plane for -. We find that there is a
substantial difference in predictions especially for , and this
difference increases out to . In particular we find that using velocity
dispersion predicts a greater number of SMBHs with masses greater than . The GWB that pulsar timing arrays find evidence for is
higher in amplitude than expected from GWB predictions which rely on high
redshift extrapolations of local SMBH mass-galaxy scaling relations. The
difference in SMBH demographics resulting from different scaling relations may
be the origin for the mismatch between the signal amplitude and predictions.
Generally, our results suggest that a deeper understanding of the potential
redshift evolution of these relations is needed if we are to draw significant
insight from their predictions at Comment: Accepted by MNRA
Effects of Inclination on Measuring Velocity Dispersion and Implications for Black Holes
The relation of central black hole mass and stellar spheroid velocity
dispersion (the M- relation) is one of the best-known and tightest
correlations linking black holes and their host galaxies. There has been much
scrutiny concerning the difficulty of obtaining accurate black hole
measurements, and rightly so; however, it has been taken for granted that
measurements of velocity dispersion are essentially straightforward. We examine
five disk galaxies from cosmological SPH simulations and find that
line-of-sight effects due to galaxy orientation can affect the measured
by 30%, and consequently black hole mass predictions by up to 1.0 dex.
Face-on orientations correspond to systematically lower velocity dispersion
measurements, while more edge-on orientations give higher velocity dispersions,
due to contamination by disk stars when measuring line of sight quantities. We
caution observers that the uncertainty of velocity dispersion measurements is
at least 20 km/s, and can be much larger for moderate inclinations. This effect
may account for some of the scatter in the locally measured M-
relation, particularly at the low-mass end. We provide a method for correcting
observed values for inclination effects based on observable
quantities.Comment: 11 pages, 7 figures, replaced with accepted versio
How important is the dark matter halo for black hole growth?
In this paper, we examine if the properties of central black holes in
galactic nuclei correlate with their host dark matter halo. We analyze the
entire sample of galaxies where black hole mass, velocity dispersion, sigma,
and asymptotic circular velocity, Vc, have all been measured. We fit M-sigma
and M-Vc to a power law, and find that in both relationships the scatter and
slope are similar. This model-independent analysis suggests that although the
black hole masses are not uniquely determined by dark matter halo mass, when
considered for the current sample as a whole, the M-Vc correlation may be as
strong (or as weak) as M-sigma. Although the data are sparse, there appears to
be more scatter in the correlation for both sigma and Vc at the low--mass end.
This is not unexpected given our current understanding of galaxy and black hole
assembly. In fact, there are several compelling reasons that account for this:
(i) SMBH formation is likely less efficient in low-mass galaxies with large
angular momentum content; (ii) SMBH growth is less efficient in low-mass disk
galaxies that have not experienced major mergers; (iii) dynamical effects, such
as gravitational recoil, increase scatter preferentially at the low-mass end.
Therefore, the recent observational claim of the absence of central SMBHs in
bulgeless, low mass galaxies, or deviations from the correlations defined by
high-mass black holes in large galaxies today is, in fact, predicated by
current models of black hole growth. We show how this arises as a direct
consequence of the coupling between dark matter halos and central black holes
at the earliest epochs.Comment: ApJ, in pres
A Chandra Survey of Supermassive Black Holes with Dynamical Mass Measurements
We present Chandra observations of 12 galaxies that contain supermassive
black holes with dynamical mass measurements. Each galaxy was observed for 30
ksec and resulted in a total of 68 point source detections in the target
galaxies including supermassive black hole sources, ultraluminous X-ray
sources, and extragalactic X-ray binaries. Based on our fits of the X-ray
spectra, we report fluxes, luminosities, Eddington ratios, and slope of the
power-law spectrum. Normalized to the Eddington luminosity, the 2--10 keV band
X-ray luminosities of the SMBH sources range from to , and
the power-law slopes are centered at with a slight trend towards
steeper (softer) slopes at smaller Eddington fractions, implying a change in
the physical processes responsible for their emission at low accretion rates.
We find 20 ULX candidates, of which six are likely ( chance) to be true
ULXs. The most promising ULX candidate has an isotropic luminosity in the
0.3--10 keV band of erg/s.Comment: Accepted by ApJ. 16 pages, 8 figures, 5 table
MRK 1216 & NGC 1277 - An orbit-based dynamical analysis of compact, high velocity dispersion galaxies
We present a dynamical analysis to infer the structural parameters and
properties of the two nearby, compact, high velocity dispersion galaxies
MRK1216 & NGC1277. Combining deep HST imaging, wide-field IFU stellar
kinematics, and complementary long-slit spectroscopic data out to 3 R_e, we
construct orbit-based models to constrain their black hole masses, dark matter
content and stellar mass-to-light ratios. We obtain a black hole mass of
log(Mbh/Msun) = 10.1(+0.1/-0.2) for NGC1277 and an upper limit of log(Mbh/Msun)
= 10.0 for MRK1216, within 99.7 per cent confidence. The stellar mass-to-light
ratios span a range of Upsilon_V = 6.5(+1.5/-1.5) in NGC1277 and Upsilon_H =
1.8(+0.5/-0.8) in MRK1216 and are in good agreement with SSP models of a single
power-law Salpeter IMF. Even though our models do not place strong constraints
on the dark halo parameters, they suggest that dark matter is a necessary
ingredient in MRK1216, with a dark matter contribution of 22(+30/-20) per cent
to the total mass budget within 1 R_e. NGC1277, on the other hand, can be
reproduced without the need for a dark halo, and a maximal dark matter fraction
of 13 per cent within the same radial extent. In addition, we investigate the
orbital structures of both galaxies, which are rotationally supported and
consistent with photometric multi-S\'ersic decompositions, indicating that
these compact objects do not host classical, non-rotating bulges formed during
recent (z <= 2) dissipative events or through violent relaxation. Finally, both
MRK 1216 and NGC 1277 are anisotropic, with a global anisotropy parameter delta
of 0.33 and 0.58, respectively. While MRK 1216 follows the trend of
fast-rotating, oblate galaxies with a flattened velocity dispersion tensor in
the meridional plane of the order of beta_z = delta, NGC 1277 is highly
tangentially anisotropic and seems to belong kinematically to a distinct class
of objects.Comment: 27 pages, 15 figures and 4 tables. Accepted for publication in MNRA
The Black Hole in the Compact, High-dispersion Galaxy NGC 1271
Located in the Perseus cluster, NGC 1271 is an early-type galaxy with a small
effective radius of 2.2 kpc and a large stellar velocity dispersion of 276 km/s
for its K-band luminosity of 8.9x10^{10} L_sun. We present a mass measurement
for the black hole in this compact, high-dispersion galaxy using observations
from the integral field spectrograph NIFS on the Gemini North telescope
assisted by laser guide star adaptive optics, large-scale integral field unit
observations with PPAK at the Calar Alto Observatory, and Hubble Space
Telescope WFC3 imaging observations. We are able to map out the stellar
kinematics on small spatial scales, within the black hole sphere of influence,
and on large scales that extend out to four times the galaxy's effective
radius. We find that the galaxy is rapidly rotating and exhibits a sharp rise
in the velocity dispersion. Through the use of orbit-based stellar dynamical
models, we determine that the black hole has a mass of (3.0^{+1.0}_{-1.1}) x
10^9 M_sun and the H-band stellar mass-to-light ratio is 1.40^{+0.13}_{-0.11}
M_sun/L_sun (1-sigma uncertainties). NGC 1271 occupies the sparsely-populated
upper end of the black hole mass distribution, but is very different from the
Brightest Cluster Galaxies (BCGs) and giant elliptical galaxies that are
expected to host the most massive black holes. Interestingly, the black hole
mass is an order of magnitude larger than expectations based on the galaxy's
bulge luminosity, but is consistent with the mass predicted using the galaxy's
bulge stellar velocity dispersion. More compact, high-dispersion galaxies need
to be studied using high spatial resolution observations to securely determine
black hole masses, as there could be systematic differences in the black hole
scaling relations between these types of galaxies and the BCGs/giant
ellipticals, thereby implying different pathways for black hole and galaxy
growth.Comment: accepted for publication in Ap
The Fundamental Plane of Black Hole Accretion and its Use as a Black Hole-Mass Estimator
We present an analysis of the fundamental plane of black hole accretion, an
empirical correlation of the mass of a black hole (), its 5 GHz radio
continuum luminosity (), and its 2-10 keV X-ray power-law
continuum luminosity (). We compile a sample of black holes with primary,
direct black hole-mass measurements that also have sensitive,
high-spatial-resolution radio and X-ray data. Taking into account a number of
systematic sources of uncertainty and their correlations with the measurements,
we use Markov chain Monte Carlo methods to fit a mass-predictor function of the
form . Our best-fit results are , , and
with the natural logarithm of the Gaussian intrinsic scatter in the log-mass
direction . This result is a
significant improvement over our earlier mass scaling result because of the
increase in active galactic nuclei sample size (from 18 to 30), improvement in
our X-ray binary sample selection, better identification of Seyferts, and
improvements in our analysis that takes into account systematic uncertainties
and correlated uncertainties. Because of these significant improvements, we are
able to consider potential influences on our sample by including all sources
with compact radio and X-ray emission but ultimately conclude that the
fundamental plane can empirically describe all such sources. We end with advice
for how to use this as a tool for estimating black hole masses.Comment: ApJ Accepted. Online interactive version of Figure 7 available at
http://kayhan.astro.lsa.umich.edu/supplementary_material/fp
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