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 $z \sim 3$. 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 $0 < z < 3$ we evaluate the inferred SMBH masses from two SMBH-galaxy scaling relations: $\mathrm{M_{BH}}$-$\mathrm{M_{bulge}}$ and $\mathrm{M_{BH}}$-$\sigma$. Our SMBH mass functions come directly from stellar mass measurements for $\mathrm{M_{BH}}$-$\mathrm{M_{bulge}}$, and indirectly from stellar mass and galaxy radius measurements along with the galaxy mass fundamental plane for $\mathrm{M_{BH}}$-$\sigma$. We find that there is a substantial difference in predictions especially for $z > 1$, and this difference increases out to $z = 3$. In particular we find that using velocity dispersion predicts a greater number of SMBHs with masses greater than $10^9 \mathrm{M}_\odot$. 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 $z > 1$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-$\sigma$ 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 $\sigma$ 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-$\sigma$ relation, particularly at the low-mass end. We provide a method for correcting observed $\sigma_{\rm los}$ 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 $10^{-8}$ to $10^{-6}$, and the power-law slopes are centered at $\sim2$ 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 ($>90$ chance) to be true ULXs. The most promising ULX candidate has an isotropic luminosity in the 0.3--10 keV band of $1.0_{-0.3}^{+0.6} \times 10^{40}$ 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 ($M$), its 5 GHz radio continuum luminosity ($\nu L_{\nu}$), and its 2-10 keV X-ray power-law continuum luminosity ($L_X$). 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 $\log(M/10^{8}\,M_{\scriptscriptstyle \odot}) = \mu_0 + \xi_{\mu R} \log(L_R / 10^{38}\,\mathrm{erg\,s^{-1}}) + \xi_{\mu X} \log(L_X / 10^{40}\,\mathrm{erg\,s^{-1}})$. Our best-fit results are $\mu_0 = 0.55 \pm 0.22$, $\xi_{\mu R} = 1.09 \pm 0.10$, and $\xi_{\mu X} = -0.59^{+0.16}_{-0.15}$ with the natural logarithm of the Gaussian intrinsic scatter in the log-mass direction $\ln\epsilon_\mu = -0.04^{+0.14}_{-0.13}$. 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