MBH-σ Relation Research Articles

A survey of molecular gas in luminous sub-millimetre galaxies

We present the results from a survey of 12CO emission in 40 luminous sub-millimetre galaxies (SMGs), with 850-μm fluxes of S850 μm = 4–20 mJy, conducted with the Plateau de Bure Interferometer. We detect 12CO emission in 32 SMGs at z ∼ 1.2–4.1, including 16 SMGs not previously published. Using multiple 12CO line (Jup = 2–7) observations, we derive a median spectral line energy distribution for luminous SMGs. We report the discovery of a fundamental relationship between 12CO FWHM and 12CO line luminosity in high-redshift starbursts, which we interpret as a natural consequence of the baryon-dominated dynamics within the regions probed by our observations. We use far-infrared luminosities to assess the star formation efficiency in our SMGs, finding that the slope of the L′CO-LFIR relation is close to linear. We derive molecular gas masses, finding a mean gas mass of (5.3 ± 1.0) × 1010 M⊙. Combining these with dynamical masses, we determine the redshift evolution of the gas content of SMGs, finding that they do not appear to be significantly more gas rich than less vigorously star-forming galaxies at high redshifts. Finally, we collate X-ray observations, and study the interdependence of gas and dynamical properties of SMGs with their AGN activity and supermassive black hole masses (MBH), finding that SMGs lie significantly below the local MBH-σ relation.

Black hole mass and radiation pressure of Seyfert 1 galaxies

We collect 214 Seyfert 1 galaxies(147 narrow line Seyfert 1 and 67 broad line Seyfert 1) and research black hole mass bulge velocity dispersion Eddington radio luminosity at 5100 Å and redshift. Our conclusions are follows: (1) when computing black hole mass, we should consider the effect of radiation pressure, especially for the narrow line Seyfert 1 galaxies; (2) when the effect of radiation pressure is considered, narrow line Seyfert 1 galaxies meet MBH-σ relation of normal galaxies and are in su-Eddington accretion; (3) in a large samples, the evolution of Seyfert 1 galaxies is from narrow line Seyfert 1 galaxies to broad line Seyfert 1 galaxies, which is consistent with other results obtained in different ways.

Narrow-Line Seyfert 1 Galaxies and the M BH -σ Relation

We have studied the location of narrow-line Seyfert 1 (NLS1) galaxies and broad-line Seyfert 1 (BLS1) galaxies on the MBH-σ relation of nonactive galaxies. We find that NLS1 galaxies as a class—as well as the BLS1 galaxies of our comparison sample—do follow the MBH-σ relation of nonactive galaxies if we use the width of the [S II] λλ6716, 6731 emission lines as a surrogate for stellar velocity dispersion, σ*. We also find that the width of [O III] λ5007 is a good surrogate for σ*, but only after (1) removal of asymmetric blue wings and, more importantly, after (2) excluding core [O III] lines with strong blueshifts (i.e., excluding galaxies which have their [O III] velocity fields dominated by radial motions, presumably outflows). The same galaxies which are extreme outliers in [O III] still follow the MBH-σ relation in [S II]. We systematically investigate the influence of several parameters on the NSL1 galaxies' location on the MBH-σ plane: [O III]core blueshift, L/LEdd, intensity ratio Fe II/Hβ, NLR density, and absolute magnitude. Implications for NLS1 models and for their evolution along the MBH-σ relation are discussed.

Fueling Low‐Level AGN Activity through Stochastic Accretion of Cold Gas

Using a simple description of feedback from black hole growth, we develop an analytic model for the fueling of Seyferts (low-luminosity active galactic nuclei [AGNs]) and their relation to their host galaxies, Eddington ratio distributions, and cosmological evolution. We derive a solution for the time evolution of accretion rates in a feedback-driven blast wave, applicable to large-scale outflows from bright quasars in galaxy mergers, low-luminosity AGNs, and black holes or neutron stars in supernova remnants. Under the assumption that cold gas stochastically accretes onto a central supermassive black hole at a rate set by the dynamics of that gas, our solution determines the evolution of Seyfert light curves. Using this model, we predict the Seyfert luminosity function, duty cycles and AGN lifetimes, and the distribution of host morphologies, Eddington ratios, and obscuration as a function of AGN luminosity and black hole mass, and we find agreement with observations at z = 0. We consider the breakdown of the contribution from this mechanism and from stellar wind and virialized hot gas accretion and merger-driven activity. We also make specific predictions for the weak evolution of the Seyfert luminosity function; i.e., luminosity function of quiescent as opposed to merger-driven activity, as a function of redshift, and for changes in both the slope and scatter of the MBH-σ relation at low MBH. Our modeling provides a quantitative and physical distinction between local, low-luminosity quiescent AGN activity and violent, merger-driven bright quasars. In our picture, the quiescent mode of fueling dominates over a wide range of luminosities (-15 MB -22) at z = 0, where most black hole growth occurs in objects with MBH 107 M☉, in S0 and Sa/b galaxies. However, quasar activity from gas-rich mergers evolves more rapidly with redshift, and by z = 1, quiescent fueling is important only at luminosities an order of magnitude or more below the break in the luminosity function. Consequently, although non-merger-driven fueling is important for black hole growth and the MBH-σ relation at low MBH, it does not significantly contribute to the black hole mass density of the universe or to cosmological backgrounds.

Cosmic Evolution of Black Holes and Spheroids. I. TheMBH‐σ Relation atz= 0.36

We test the evolution of the correlation between black hole mass and bulge velocity dispersion (MBH-σ), using a carefully selected sample of 14 Seyfert 1 galaxies at z = 0.36±0.01. We measure velocity dispersion from stellar absorption lines around Mg b (5175 A) and Fe (5270 A) using high-S/N Keck spectra and estimate black hole mass from the Hβ line width and the optical luminosity at 5100 A, based on the empirically calibrated photoionization method. We find a significant offset from the local relation, in the sense that velocity dispersions were smaller for given black hole masses at z = 0.36 than locally. We investigate various sources of systematic uncertainties and find that those cannot account for the observed offset. The measured offset is Δlog MBH = 0.62 ±0.10±0.25; i.e., Δlog σ = 0.15±0.03±0. 06, where the error bars include a random component and an upper limit to the systematics. At face value, this result implies a substantial growth of bulges in the last 4 Gyr, assuming that the local MBH-σ relation is the universal evolutionary endpoint. Along with two samples of active galaxies with consistently determined black hole mass and stellar velocity dispersion taken from the literature, we quantify the observed evolution with the best-fit linear relation: Δlog MBH = (1-66±0.43)z + (0.04±0.09) with respect to the local relationship of Tremaine and coworkers, and Δlog MBH = (1-55 ±0.46)z + (0.01 ±0.12) with respect to that of Ferrarese. This result is consistent with the growth of black holes predating the final growth of bulges at these mass scales (〈σ〉 = 170 km s-1). © 2006. The American Astronomical Society. All rights reserved.

VLT Diffraction‐limited Imaging and Spectroscopy in the NIR: Weighing the Black Hole in Centaurus A with NACO

We present high spatial resolution near-infrared spectra and images of the nucleus of Centaurus A (NGC 5128) obtained with NAOS-CONICA at the VLT. The adaptive optics-corrected data have a spatial resolution of 006 (FWHM) in K and 011 in H band, 4 times higher than previous studies. The kinematics of the ionized gas ([Fe II]) are mapped along four slit positions. The observed gas motions suggest a kinematically hot disk that is orbiting a central object and is oriented nearly perpendicular to the nuclear jet. We model the central rotation and velocity dispersion curves of the [Fe II] gas in the combined potential of the stellar mass and the (dominant) black hole. Our physically most plausible model, a dynamically hot and geometrically thin gas disk, yields a black hole mass of Mbh = 6.1 × 107 M☉. As the physical state of the gas is not well understood, we also consider two limiting cases: first, a cold disk model, which completely neglects the velocity dispersion but is in line with many earlier gas disk models; it yields an Mbh estimate that is almost 2 times lower. Second, a spherical gas distribution in hydrostatic equilibrium via the Jeans equation; the best-fit black hole mass increases by a factor of 1.5. This wide mass range spanned by the limiting cases shows how important the gas physics is even for high-resolution data. Our overall best-fitting black hole mass is a factor of 2-4 lower than previous measurements. A substantially lower Mbh estimate when using higher resolution kinematics was also found for many other black hole mass measurements as HST data became available. With our revised Mbh estimate, Cen A's offset from the Mbh-σ relation is significantly reduced.

The AGN-Starburst Connection, Galactic Superwinds, and M BH -σ

Recent observations of young galaxies at redshifts z ~ 3 have revealed simultaneous AGN and starburst activity, as well as galaxy-wide superwinds. I show that there is probably a close connection between these phenomena by extending an earlier treatment of the MBH-σ relation. As the black hole grows, an outflow drives a shell into the surrounding gas. This stalls after a dynamical time at a size determined by the hole's current mass and thereafter grows on the Salpeter timescale. The gas trapped inside this bubble cools, forms stars, and is recycled as accretion and outflow. The consequent high metallicity agrees with that commonly observed in AGN accretion. Once the hole reaches a critical mass, this region attains a size such that the gas can no longer cool efficiently. The resulting energy-driven flow expels the remaining gas as a superwind, fixing both the MBH-σ relation and the total stellar bulge mass at values in good agreement with observations. Black hole growth thus produces starbursts and ultimately a superwind.

Dwarf Seyfert 1 Nuclei and the Low-Mass End of the M BH -σ Relation

To examine the relationship between black hole mass and host galaxy velocity dispersion for low black hole masses, we have measured the velocity dispersions of 15 Seyfert 1 galaxies from the recent catalog of Greene & Ho. These Seyfert galaxies were selected from the Sloan Digital Sky Survey to have estimated black hole masses below 106 M☉. The data are consistent with a straightforward downward extrapolation of the local MBH-σ relation, indicating that this correlation extends over a range of more than 4 orders of magnitude in black hole mass. The rms scatter of the sample about the extrapolated MBH-σ relation is 0.57 dex, consistent with the expected scatter of single-epoch mass estimates for Seyfert 1 galaxies.

M BH - Relation for a Complete Sample of Soft X-Ray-selected Active Galactic Nuclei

We present the black hole mass-bulge velocity dispersion relation for a complete sample of 75 soft X-ray-selected active galactic nuclei (AGNs): 43 broad-line Seyfert 1 galaxies (BLS1s) and 32 narrow-line Seyfert 1 galaxies (NLS1s). We use luminosity and FWHM(Hβ) as surrogates for black hole mass and FWHM([O III]) as a surrogate for the bulge velocity dispersion. We find that NLS1s lie below the MBH-σ relation of BLS1s, confirming the Mathur et al. result. The statistical result is robust and not due to any systematic measurement error. This has important consequences toward our understanding of black hole formation and growth: black holes grow by accretion in well-formed bulges, possibly after a major merger. As they grow, they get closer to the MBH-σ relation for normal galaxies. The accretion is highest in the beginning and dwindles as the time goes by. Our result does not support theories of MBH-σ relation in which the black hole mass is a constant fraction of the bulge mass/velocity dispersion at all times or those in which bulge growth is controlled by AGN feedback.

Observational evidence for a connection between SMBHs and dark matter haloes

We investigate the relation between circular velocity vc and bulge velocity dispersion σ in spiral galaxies, based on literature data and new spectroscopic observations. We find a strong, nearly linear vc−σ correlation with a negligible intrinsic scatter, and a striking agreement with the corresponding relation for elliptical galaxies. The least massive galaxies (σ<80 km s−1) significantly deviate from this relation. We combine this vc−σ correlation with the well-known MBHσ relation to obtain a tight correlation between circular velocity and supermassive black hole mass, and interpret this as observational evidence for a close link between supermassive black holes and the dark matter haloes in which they presumably formed. Apart from being an important ingredient for theoretical models of galaxy formation and evolution, the relation between MBH and circular velocity has the potential to become an important practical tool in estimating supermassive black hole masses in spiral galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Self‐regulated Growth of Supermassive Black Holes in Galaxies as the Origin of the Optical and X‐Ray Luminosity Functions of Quasars

We postulate that supermassive black holes grow in the centers of galaxies until they unbind the galactic gas that feeds them. We show that the corresponding self-regulation condition yields a correlation between black hole mass (Mbh) and galaxy velocity dispersion (σ) as inferred in the local universe and recovers the observed optical and X-ray luminosity functions of quasars at redshifts up to z ~ 6 based on the hierarchical evolution of galaxy halos in a Λ-dominated cold dark matter cosmology. With only one free parameter and a simple algorithm, our model yields the observed evolution in the number density of optically bright or X-ray-faint quasars with 2 z 6 across 3 orders of magnitude in bolometric luminosity and 3 orders of magnitude in comoving density per logarithm of luminosity. The self-regulation condition identifies the dynamical time of galactic disks during the epoch of peak quasar activity (z ~ 2.5) as the origin of the inferred characteristic quasar lifetime of ~107 yr. Since the lifetime becomes comparable to the Salpeter e-folding time at this epoch, the model also implies that the Mbh-σ relation is a product of feedback-regulated accretion during the peak of quasar activity. The mass density in black holes accreted by that time is consistent with the local black hole mass density ρbh ~ (2.3) × 105 M☉ Mpc-3, which we have computed by combining the Mbh-σ relation with the measured velocity dispersion function of Sloan Digital Sky Survey galaxies. Comparison of the local black hole mass function with that inferred from combining the feedback relation with the halo mass function suggests that most massive (>109 M☉) black holes may have already been in place by z ~ 6. Applying a similar self-regulation principle to supernova-driven winds from starbursts, we find that the local ratio between the black hole mass and the stellar mass of galactic spheroids should be ~0.001, independent of mass and in agreement with observations. This ratio increases with redshift, although the Mbh-σ relation is redshift-independent.

Black Hole Growth and Activity in a Λ Cold Dark Matter Universe

The observed properties of supermassive black holes suggest a fundamental link between their assembly and the formation of their host spheroids. We model the growth and activity of black holes in galaxies using Λ cold dark matter cosmological hydrodynamic simulations by following the evolution of the baryonic mass component in galaxy potential wells. We find that the observed steep relation between black hole mass and spheroid velocity dispersion, MBH σ4, is reproduced if the gas mass in bulges is linearly proportional to the black hole mass. To a good approximation, this is equivalent to assuming the conversion of a fixed fraction of gas mass into black hole mass. In this model, star formation and supernova feedback in the gas are sufficient for regulating and limiting the growth of the central black hole and of its gas supply. Black hole growth saturates because of the competition with star formation and, in particular, feedback, both of which determine the gas fraction available for accretion. Unless other processes also operate, we predict that the MBH-σ relation is not set in primordial structures but is fully established at low redshifts, z 2, and is shallower at earlier times. Once this relation is established, we find that central black hole masses are related to their dark matter halos simply via MBH ≈ M. We assume that galaxies undergo a quasar phase with a typical lifetime, tQ ~ 2 × 107 yr, the only free parameter of the model, and show that star formation-regulated depletion of gas in spheroids is sufficient to explain, for the most part, the decrease of the quasar population at redshift z < 3 in the optical blue band. However, with the simplest assumption of a redshift-independent quasar lifetime, the model slightly overpredicts optical quasar numbers at high redshifts, although it yields the observed evolution of number density of X-ray-faint quasars over the whole redshift range 1 < z < 6. Finally, we find that the majority of black hole mass is assembled in galaxies by z ~ 3 and that the black hole accretion rate density peaks in rough correspondence to the star formation rate density at z ~ 4-5.

The Slope of the Black Hole Mass versus Velocity Dispersion Correlation

Observations of nearby galaxies reveal a strong correlation between the mass of the central dark object MBH and the velocity dispersion σ of the host galaxy, of the form log(MBH/M☉) = α + β log(σ/σ0); however, published estimates of the slope β span a wide range (3.75-5.3). Merritt & Ferrarese have argued that low slopes (≲4) arise because of neglect of random measurement errors in the dispersions and an incorrect choice for the dispersion of the Milky Way Galaxy. We show that these explanations and several others account for at most a small part of the slope range. Instead, the range of slopes arises mostly because of systematic differences in the velocity dispersions used by different groups for the same galaxies. The origin of these differences remains unclear, but we suggest that one significant component of the difference results from Ferrarese & Merritt's extrapolation of central velocity dispersions to re/8 (re is the effective radius) using an empirical formula. Another component may arise from dispersion-dependent systematic errors in the measurements. A new determination of the slope using 31 galaxies yields β = 4.02 ± 0.32, α = 8.13 ± 0.06 for σ0 = 200 km s-1. The MBH-σ relation has an intrinsic dispersion in log MBH that is no larger than 0.25-0.3 dex and may be smaller if observational errors have been underestimated. In an appendix, we present a simple kinematic model for the velocity-dispersion profile of the Galactic bulge.

The Counterrotating Core and the Black Hole Mass of IC 1459

The E3 giant elliptical galaxy IC 1459 is the prototypical galaxy with a fast counterrotating stellar core. We obtained one Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) long-slit spectrum along the major axis of this galaxy and Cerro Tololo Inter-American Observatory (CTIO) spectra along five position angles. The signal-to-noise ratio (S/N) of the ground-based data is such that also the higher order Gauss-Hermite moments (h3-h6) can be extracted reliably. We present self-consistent three-integral axisymmetric models of the stellar kinematics, obtained with Schwarzschild's numerical orbit superposition method. The available data allow us to study the dynamics of the kinematically decoupled core (KDC) in IC 1459, and we find that it consists of stars that are well separated from the rest of the galaxy in phase space. In particular, our study indicates that the stars in the KDC counterrotate in a disk on orbits that are close to circular. We estimate that the KDC mass is ≈0.5% of the total galaxy mass or ≈3 × 109 M☉. We estimate the central black hole (BH) mass MBH of IC 1459 independently from both its stellar and its gaseous kinematics. Although both tracers rule out models without a central BH, neither yields a particularly accurate determination of the BH mass. The main problem for the stellar dynamical modeling is the fact that the modest S/N of the STIS spectrum and the presence of strong gas emission lines preclude measuring the full line-of-sight velocity distribution (LOSVD) at HST resolution. The main problem for the gasdynamical modeling is that there is evidence that the gas motions are disturbed, possibly as a result of nongravitational forces acting on the gas. These complications probably explain why we find rather discrepant BH masses with the different methods. The stellar kinematics suggest that MBH = (2.6 ± 1.1) × 109 M☉ (3 σ error). The gas kinematics suggests that MBH ≈ 3.5 × 108 M☉ if the gas is assumed to rotate at the circular velocity in a thin disk. If the observed velocity dispersion of the gas is assumed to be gravitational, then MBH could be as high as ~1.0 × 109 M☉. These different estimates bracket the value MBH = (1.1 ± 0.3) × 109 M☉ predicted by the MBH-σ relation. It will be an important goal for future studies to attempt comparisons of BH mass determinations from stellar and gaseous kinematics for other galaxies. This will assess the reliability of BH mass determinations with either technique. This is essential if one wants to interpret the correlation between the BH mass and other global galaxy parameters (e.g., velocity dispersion) and in particular the scatter in these correlations (believed to be only ~0.3 dex).

Black Hole Growth in Dark Matter and theMBH‐σ Relation

In this paper, we consider the growth of seed black holes immersed in dark matter halos. We investigate first the adiabatic growth in various initial distribution functions (isothermal; power law; and Navarro, Frenk, and White) and find the resulting density, radial velocity, and anisotropy profiles. In addition, we estimate the growth rate for a given black hole mass in the corresponding adiabatically modified dark matter distribution function. Only in the isothermal case is there a convincing black hole mass-age relation. By calculating the line-of-sight velocity dispersion for the various cases as a function of the black hole mass, we find the predicted adiabatic MBH-σ relation, which never approaches the recently observed power law. We conclude by abandoning adiabaticity, suggesting that the black hole grows proportionally to the dark matter halo itself on a dynamic timescale. This allows us to relate the observed MBH-σ relation to the cosmological power spectrum on galactic scales by using dimensional scaling arguments.

On the black hole-bulge mass relation in active and inactive galaxies

New black hole mass estimates are presented for a sample of 72 active galactic nuclei (AGNs) covering three decades in optical luminosity. Using a subsample of Seyfert galaxies, which have black hole mass estimates from both reverberation mapping and stellar velocity dispersions, we investigate the geometry of the AGNs’ broad-line region. It is demonstrated that a model in which the orbits of the line-emitting material have a flattened geometry is favoured over randomly-orientated orbits. Using this model we investigate the Mbh-Lbulge relation for a combined 90-object sample consisting of the AGNs plus a sample of 18 nearby inactive elliptical galaxies with dynamical black hole mass measurements. It is found that, for all reasonable mass-to-light ratios, the Mbh-Lbulge relation is equivalent to a linear scaling between bulge and black hole mass. The best-fitting normalization of the Mbh-Mbulge relation is found to be Mbh=0.0012Mbulge, in agreement with recent black hole mass studies based on stellar velocity dispersions. Furthermore, the scatter around the Mbh-Lbulge relation for the full sample is found to be significantly smaller than has been previously reported (Δlog Mbh=0.39 dex). Finally, using the nearby inactive elliptical galaxy sample alone, it is shown that the scatter in the Mbh-Lbulge relation is only 0.33 dex, comparable with that of the Mbh-σ relation. These results indicate that reliable black hole mass estimates can be obtained for high redshift galaxies.

A Fundamental Relation between Supermassive Black Holes and Their Host Galaxies

The masses of supermassive black holes correlate almost perfectly with the velocity dispersions of their host bulges, Mbh ∝ σα, where α = 4.8 ± 0.5. The relation is much tighter than the relation between Mbh and bulge luminosity, with a scatter no larger than expected on the basis of measurement error alone. Black hole masses recently estimated by Magorrian et al. lie systematically above the Mbh-σ relation defined by more accurate mass estimates, some by as much as 2 orders of magnitude. The tightness of the Mbh-σ relation implies a strong link between black hole formation and the properties of the stellar bulge.