Recent SMBH Projects
- Disk–Jet Coupling in NGC 4395
- What’s on Tap?
- Swift Galactic Plane Survey Discovery of a Galactic Supernova Remnant
- Regulation of Black Hole Winds and Jets
- What does an accretion disk with a gap in it look like?
- Discovery of a gigantic black hole (1.7 × 1011 M☉) in NGC 1277, a modestly sized galaxy
- Discovery of a QPO in a Tidal Disruption Event
- A Survey of SMBHs with Chandra
- Is There a Black Hole in NGC 4382?
- Orbit Based Dynamical Models of the Sombreo Galaxy
- X-Ray and Radio Constraints on the Mass of the Black Hole in Swift J164449.3+573451
- Observational Selection Effects and the M–σ Relation
- The Black Hole Mass in M87 from Gemini/NIFS Adaptive Optics Observations
- A Distinctive Disk-Jet Coupling in the Seyfert-1 Active Galactic Nucleus NGC 4051
- The Fundamental Plane of Black Hole Accretion
- The Intrinsic Scatter in Black Hole Scaling Relations
- Five Black Hole Mass Measurements.
G306.3−0.9: A newly discovered young galactic supernova remnant
(2013), G306.3−0.9: A Newly Discovered Young Galactic Supernova Remnant ApJ, 766, 112.
We discovered a new supernova remnant (SNR), G306.3-0.9, with the Swift Galactic Plane Survey. We followed it up with new Chandra and radio observations. Chandra imaging reveals a complex morphology, dominated by a bright shock. The X-ray spectrum is broadly consistent with a young SNR in the Sedov phase, implying an age of 2500 yr for a distance of 8 kpc, plausibly identifying this as one of the 20 youngest Galactic SNRs. Australia Telescope Compact Array (ATCA) imaging reveals a prominent ridge of radio emission that correlates with the X-ray emission. We find a flux density of ~160 mJy at 1 GHz, which is the lowest radio flux recorded for a Galactic SNR to date. The remnant is also detected at 24 μm, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant. I recognize that this is not a supermassive black hole, but I didn't have anywhere else obvious to put it. Besides, have you seen the image below?[+] Toggle Figure
What does an accretion disk with a gap in it look like?
(2012), “Observable Consequences of Merger-Driven Gaps and Holes in Black Hole Accretion Disks,” ApJ, 761, 90.
We calculate the observable signature of a black hole (BH) accretion disk with a gap or a hole created by a secondary BH embedded in the disk. We find that for an interesting range of parameters of BH masses (~106–109 M☉), orbital separation (~1 AU to ~0.1 pc), and gap width (10-190 disk scale heights), the missing thermal emission from a gap manifests itself in an observable decrement in the spectral energy distribution (SED). We present observational diagnostics in terms of power-law forms that can be fit to line-free regions in active galactic nucleus (AGN) spectra or in fluxes from sequences of broad filters. Most interestingly, the change in slope in the broken power law is almost entirely dependent on the width of the gap in the accretion disk, which in turn is uniquely determined by the mass ratio of the BHs, such that it scales roughly as q5/12. Thus, one can use spectral observations of the continuum of bright AGNs to infer not only the presence of a closely separated BH binary, but also the mass ratio. When the BH merger opens an entire hole (or cavity) in the inner disk, the broadband SED of the AGNs or quasar may serve as a diagnostic. Such sources should be especially luminous in optical bands but intrinsically faint in X-rays (i.e., not merely obscured). We briefly note that viable candidates may have already been identified, though extant detailed modeling of those with high-quality data have not yet revealed an inner cavity.[+] Toggle Figure
Discovery of a gigantic black hole in a modestly sized galaxy
(2012), “An over-massive black hole in the compact lenticular galaxy NGC1277, ” Nature, 491, 729.
Most massive galaxies have supermassive black holes at their centres, and the masses of the black holes are believed to correlate with properties of the host-galaxy bulge component. Several explanations have been proposed for the existence of these locally established empirical relationships, including the non-causal, statistical process of galaxy-galaxy merging, direct feedback between the black hole and its host galaxy, and galaxy-galaxy merging and the subsequent violent relaxation and dissipation. The empirical scaling relations are therefore important for distinguishing between various theoretical models of galaxy evolution, and they furthermore form the basis for all black-hole mass measurements at large distances. Observations have shown that the mass of the black hole is typically 0.1 per cent of the mass of the stellar bulge of the galaxy. Until now, the galaxy with the largest known fraction of its mass in its central black hole (11 per cent) was the small galaxy NGC4486B. Here we report observations of the stellar kinematics of NGC1277, which is a compact, lenticular galaxy with a mass of 1.2×1011 solar masses. From the data, we determine that the mass of the central black hole is 1.7×1010 solar masses, or 59 per cent of its bulge mass. We also show observations of five other compact galaxies that have properties similar to NGC1277 and therefore may also contain over-massive black holes. It is not yet known if these galaxies represent a tail of a distribution, or if disk-dominated galaxies fail to follow the usual black-hole mass scaling relations.[+] Toggle Figure
Discovery of a Quasi Periodic Oscillation in a Tidal Disruption Event
(2012), A 200-Second Quasi-Periodicity After the Tidal Disruption of a Star by a Dormant Black Hole Science, 337, 949.
Supermassive black holes (SMBHs; mass is greater than or approximately 105 times that of the Sun) are known to exist at the center of most galaxies with sufficient stellar mass. In the local universe, it is possible to infer their properties from the surrounding stars or gas. However, at high redshifts we require active, continuous accretion to infer the presence of the SMBHs, which often comes in the form of long-term accretion in active galactic nuclei. SMBHs can also capture and tidally disrupt stars orbiting nearby, resulting in bright flares from otherwise quiescent black holes. Here, we report on a ~200-second x-ray quasi-periodicity around a previously dormant SMBH located in the center of a galaxy at redshift z = 0.3534. This result may open the possibility of probing general relativity beyond our local universe.[+] Toggle Figure
A Chandra Survey of SMBHs with Dynamically Determined Masses
(2012), “A Chandra Survey of Supermassive Black Holes with Dynamical Mass Measurements,” ApJ, 749, 129.
We present Chandra observations of 12 galaxies that contain supermassive black holes (SMBHs) with dynamical mass measurements. Each galaxy was observed for 30 ks and resulted in a total of 68 point-source detections in the target galaxies including SMBH sources, ultraluminous X-ray sources (ULXs), 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 ~2 with a slight trend toward 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 6 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+0.6−0.3 × 1040 erg s−1.[+] Toggle Figure
Is the M–σ Relation an Upper Limit Relation?
(2011), “Observational Selection Effects and the M–σ Relation,” ApJ, 738, 17.
We examine the possibility that the observed relation between black hole mass and host-galaxy stellar velocity dispersion (the M–σ relation) is biased by an observational selection effect, the difficulty of detecting a black hole whose sphere of influence is smaller than the telescope resolution. In particular, we critically investigate recent claims that the M–σ relation only represents the upper limit to a broad distribution of black hole masses in galaxies of a given velocity dispersion. We find that this hypothesis can be rejected at a high confidence level, at least for the early-type galaxies with relatively high velocity dispersions (median 268 km s−1) that comprise most of our sample. We also describe a general procedure for incorporating observational selection effects in estimates of the properties of the M–σ relation. Applying this procedure we find results that are consistent with earlier estimates that did not account for selection effects, although with larger error bars. In particular, (1) the width of the M–σ relation is not significantly increased, (2) the slope and normalization of the M–σ relation are not significantly changed, and (3) most or all luminous early-type galaxies contain central black holes at zero redshift. Our results may not apply to late-type or small galaxies, which are not well represented in our sample.
The Fundamental Plane of Accretion onto Black Holes with Dynamical Masses
(2009c), Fundamental Plane of Accretion onto Black Holes with Dynamical Masses ApJ, 706, 404.
Black hole accretion and jet production are areas of intensive study in astrophysics. Recent work has found a relation between radio luminosity, X-ray luminosity, and black hole mass. With the assumption that radio and X-ray luminosities are suitable proxies for jet power and accretion power, respectively, a broad fundamental connection between accretion and jet production is implied. In an effort to refine these links and enhance their power, we have explored the above relations exclusively among black holes with direct, dynamical mass-measurements. This approach not only eliminates systematic errors incurred through the use of secondary mass measurements, but also effectively restricts the range of distances considered to a volume-limited sample. Further, we have exclusively used archival data from the Chandra X-ray Observatory to best isolate nuclear sources. We find log LR = (4.80 ± 0.24) + (0.78 ± 0.27)log M BH + (0.67 ± 0.12)log LX , in broad agreement with prior efforts. Owing to the nature of our sample, the plane can be turned into an effective mass predictor. When the full sample is considered, masses are predicted less accurately than with the well-known M-σ relation. If obscured active galactic nuclei are excluded, the plane is potentially a better predictor than other scaling measures.[+] Toggle Figure
The M–σ and M–L Relations in Galactic Bulges, and Determinations of Their Intrinsic Scatter
(2009b), The M–σ and M–L Relations in Galactic Bulges, and Determinations of Their Intrinsic Scatter ApJ, 698, 198.
We derive improved versions of the relations between supermassive black hole mass (MBH) and host-galaxy bulge velocity dispersion (σ) and luminosity (L; the M–σ and M–L relations), based on 49 MBH measurements and 19 upper limits. Particular attention is paid to recovery of the intrinsic scatter (ε0) in both relations. We find log(MBH / M⊙) = α + β * log(σ / 200 km/s) with (α, β, ε0) = (8.12 ± 0.08, 4.24 ± 0.41, 0.44 ± 0.06) for all galaxies and (α, β, ε0) = (8.23 ± 0.08, 3.96 ± 0.42, 0.31 ± 0.06) for ellipticals. The results for ellipticals are consistent with previous studies, but the intrinsic scatter recovered for spirals is significantly larger. The scatter inferred reinforces the need for its consideration when calculating local black hole mass function based on the M-sigma relation, and further implies that there may be substantial selection bias in studies of the evolution of the M–σ relation. We estimate the M–L relationship as log(MBH / M⊙) = α + β * log(LV / 1011 L⊙,V) of (α, β, ε0) = (8.95 ± 0.11, 1.11 ± 0.18, 0.38 ± 0.09); using only early-type galaxies. These results appear to be insensitive to a wide range of assumptions about the measurement errors and the distribution of intrinsic scatter. We show that culling the sample according to the resolution of the black hole’s sphere of influence biases the relations to larger mean masses, larger slopes, and incorrect intrinsic residuals.[+] Toggle Figure
A Quintet of Black Hole Mass Determinations
(2009a), A Quintet of Black Hole Mass Determinations ApJ, 695, 1577.
We report five new measurements of central black hole masses based on
Space Telescope Imaging Spectrograph (STIS) and Wide Field Planetary Camera 2
(WFPC2) observations with the Hubble Space Telescope (HST)
axisymmetric, three-integral, Schwarzschild orbit-library kinematic
models. We selected a sample of galaxies within a narrow range in
velocity dispersion that cover a range of galaxy parameters (including
Hubble type and core/power-law surface density profile) where we
expected to be able to resolve the galaxy’s sphere of influence
based on the predicted value of the black hole mass from the
M–σ relation. We find masses for the following
NGC 3607, MBH = 1.2 (+0.4, -0.4) × 108 M⊙;
NGC 4026, MBH = 2.1 (+0.7, -0.4) × 108 M⊙; and
NGC 5576, MBH = 1.8 (+0.3, -0.4) × 108 M⊙,
all significantly excluding MBH = 0. For
which is significantly below predictions from M–σ and M–L relations and consistent with MBH = 0, though the presence of a double bar in this galaxy may present problems for our axisymmetric code.[+] Toggle Figure