Abstract
We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 5 and Cycle 6 observations of CO (2−1) and CO (3−2) emission at 0.″2−0.″3 resolution in two radio-bright, brightest ...group/cluster early-type galaxies, NGC 315 and NGC 4261. The data resolve CO emission that extends within their black hole (BH) spheres of influence (
r
g
), tracing regular Keplerian rotation down to just tens of parsecs from the BHs. The projected molecular gas speeds in the highly inclined (
i
≳ 60°) disks rise at least to 500 km s
−1
near their galaxy centers. We fit dynamical models of thin-disk rotation directly to the ALMA data cubes and account for the extended stellar mass distributions by constructing galaxy surface brightness profiles corrected for a range of plausible dust extinction values. The best-fit models yield
for NGC 315 and
for NGC 4261, the latter of which is larger than previous estimates by a factor of ∼3. The BH masses are broadly consistent with the relations between BH masses and host galaxy properties. These are among the first ALMA observations to map dynamically cold gas kinematics well within the BH-dominated regions of radio galaxies, resolving the respective
r
g
by factors of ∼5−10. The observations demonstrate ALMA’s ability to precisely measure BH masses in active galaxies, which will enable more confident probes of accretion physics for the most massive galaxies.
Ultra-compact dwarf galaxies are among the densest stellar systems in the Universe. These systems have masses of up to 2 × 10(8) solar masses, but half-light radii of just 3-50 parsecs. Dynamical ...mass estimates show that many such dwarfs are more massive than expected from their luminosity. It remains unclear whether these high dynamical mass estimates arise because of the presence of supermassive black holes or result from a non-standard stellar initial mass function that causes the average stellar mass to be higher than expected. Here we report adaptive optics kinematic data of the ultra-compact dwarf galaxy M60-UCD1 that show a central velocity dispersion peak exceeding 100 kilometres per second and modest rotation. Dynamical modelling of these data reveals the presence of a supermassive black hole with a mass of 2.1 × 10(7) solar masses. This is 15 per cent of the object's total mass. The high black hole mass and mass fraction suggest that M60-UCD1 is the stripped nucleus of a galaxy. Our analysis also shows that M60-UCD1's stellar mass is consistent with its luminosity, implying a large population of previously unrecognized supermassive black holes in other ultra-compact dwarf galaxies.
ABSTRACT We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 3 observations of CO(2-1) emission from the circumnuclear disk in the E/S0 galaxy NGC 1332 at 0 044 resolution. The disk ...exhibits regular rotational kinematics and central high-velocity emission ( 500 km s−1) consistent with the presence of a compact central mass. We construct models for a thin, dynamically cold disk in the gravitational potential of the host galaxy and black hole and fit the beam-smeared model line profiles directly to the ALMA data cube. Model fits successfully reproduce the disk kinematics out to r = 200 pc. Fitting models just to spatial pixels within projected r = 50 pc of the nucleus (two times larger than the black hole's gravitational radius of influence), we find M BH = ( 6.64 − 0.63 + 0.65 ) × 10 8 M . This observation demonstrates ALMA's powerful capability to determine the masses of supermassive black holes by resolving gas kinematics on small angular scales in galaxy nuclei.
The recent discovery of massive black holes (BHs) in the centers of high-mass ultra-compact dwarf galaxies (UCDs) suggests that at least some are the stripped nuclear star clusters of dwarf galaxies. ...We present the first study that investigates whether such massive BHs, and therefore stripped nuclei, also exist in low-mass (M < 107 M ) UCDs. We constrain the BH masses of two UCDs located in Centaurus A (UCD 320 and UCD 330) using Jeans modeling of the resolved stellar kinematics from adaptive optics data obtained with the SINFONI integral field spectrograph at the Very Large Telescope (VLT/SINFONI). No massive BHs are found in either UCD. We find a 3 upper limit on the central BH mass in UCD 330 of M < 1.0 × 105 M , which corresponds to 1.7% of the total mass. This excludes a high-mass fraction BH and would only allow low-mass BHs similar to those claimed to be detected in Local Group globular clusters. For UCD 320, poorer data quality results in a less constraining 3 upper limit of M < 1 × 106 M , which is equal to 37.7% of the total mass. The dynamical mass-to-light ratios of UCD 320 and UCD 330 are not inflated compared to predictions from stellar population models. The non-detection of BHs in these low-mass UCDs is consistent with the idea that elevated dynamical mass-to-light ratios do indicate the presence of a substantial BH. Although no massive BHs are detected, these systems could still be stripped nuclei. The strong rotation (v/ of 0.3-0.4) in both UCDs and the two-component light profile in UCD 330 support the idea that these UCDs may be stripped nuclei of low-mass galaxies whose BH occupation fraction is not yet known.
Abstract
We present 0.″14 resolution Atacama Large Millimeter/submillimeter Array (ALMA) CO(2−1) observations of the circumnuclear gas disk in UGC 2698, a local compact galaxy. The disk exhibits ...regular rotation with projected velocities rising to 450 km s
−1
near the galaxy center. We fit gas-dynamical models to the ALMA data cube, assuming the CO emission originates from a dynamically cold, thin disk, and measured the mass of the supermassive black hole (BH) in UGC 2698 to be
M
BH
= (2.46 ± 0.07 1
σ
statistical
−
0.78
+
0.70
systematic) × 10
9
M
⊙
. UGC 2698 is part of a sample of nearby early-type galaxies that are plausible
z
∼ 2 red nugget relics. Previous stellar-dynamical modeling for three galaxies in the sample found BH masses consistent with the BH mass−stellar velocity dispersion (
M
BH
−
σ
⋆
) relation but over-massive relative to the BH mass−bulge luminosity (
M
BH
−
L
bul
) correlation, suggesting that BHs may gain the majority of their mass before their host galaxies. However, UGC 2698 is consistent with both
M
BH
−
σ
⋆
and
M
BH
−
L
bul
. As UGC 2698 has the largest stellar mass and effective radius in the local compact galaxy sample, it may have undergone more recent mergers that brought it in line with the BH scaling relations. Alternatively, given that the three previously measured compact galaxies are outliers from
M
BH
−
L
bul
, while UGC 2698 is not, there may be significant scatter at the poorly sampled high-mass end of the relation. Additional gas-dynamical
M
BH
measurements for the compact galaxy sample will improve our understanding of BH−galaxy co-evolution.
We measure the stellar populations as a function of the radius for 90 early-type galaxies (ETGs) in the MASSIVE survey, a volume-limited integral-field spectroscopic (IFS) galaxy survey targeting all ...northern-sky ETGs with an absolute K-band magnitude of MK < −25.3 mag or a stellar mass of , within 108 Mpc. We are able to measure reliable stellar population parameters for individual galaxies out to 10-20 kpc (1-3 Re) depending on the galaxy. Focusing on ∼Re (∼10 kpc), we find significant correlations between the abundance ratios, , and at a large radius, but we also find that the abundance ratios saturate in the highest-mass bin. We see a strong correlation between the kurtosis of the line-of-sight velocity distribution (h4) and the stellar population parameters beyond Re. Galaxies with higher radial anisotropy appear to be older, with metal-poorer stars and enhanced /Fe. We suggest that the higher radial anisotropy may derive from more accretion of small satellites. Finally, we see some evidence for correlations between environmental metrics (measured locally and on >5 Mpc scales) and the stellar populations, as expected if satellites are quenched earlier in denser environments.
We use high spatial resolution stellar velocity maps from the Gemini integral-field spectrograph (IFS) and wide-field velocity maps from the McDonald Mitchell IFS to study the stellar velocity ...profiles and kinematic misalignments from ∼200 pc to ∼20 kpc in 20 early-type galaxies (ETGs) with stellar mass M* > 1011.7M in the MASSIVE survey. While 80% of the galaxies have low spins (λ < 0.1) and low rotational velocities (<50 km s−1) in both the central region and the main body, we find a diverse range of velocity features and misalignment angles. For the 18 galaxies with measurable central kinematic axes, 10 have well aligned kinematic axis and photometric major axis, and the other eight galaxies have misalignment angles that are distributed quite evenly from 15° to the maximal value of 90°. There is a strong correlation between central kinematic misalignment and galaxy spin, where all four galaxies with significant spins have well aligned kinematic and photometric axes, but only 43% of the low-spin galaxies are well aligned. The central and main-body kinematic axes within a galaxy are not always aligned. When the two kinematic axes are aligned (∼60% of the cases), they are either also aligned with the photometric major axis or orthogonal to it. We find 13 galaxies to also exhibit noticeable local kinematic twists, and one galaxy to have a counterrotating core. A diverse assembly history consisting of multiple gas-poor mergers of a variety of progenitor mass ratios and orbits is likely to be needed to account for the predominance of low spins and the wide range of central and main-body velocity features reported here for local massive ETGs.
Abstract
The origin of ultracompact dwarfs (UCDs), a class of compact stellar systems discovered two decades ago, still remains a matter of debate. Recent discoveries of central supermassive black ...holes in UCDs likely inherited from their massive progenitor galaxies provide support for the tidal stripping hypothesis. At the same time, on statistical grounds, some massive UCDs might be representatives of the high luminosity tail of the globular cluster luminosity function. Here we present a detection of a $3.3^{+1.4}_{-1.2}\times 10^6\,M_{{\odot }}$ black hole (1σ uncertainty) in the centre of the UCD3 galaxy in the Fornax cluster, which corresponds to 4 per cent of its stellar mass. We performed isotropic Jeans dynamical modelling of UCD3 using internal kinematics derived from adaptive optics-assisted observations with the SINFONI spectrograph and seeing limited data collected with the FLAMES spectrograph at the ESO VLT. We rule out the zero black hole mass at the 3σ confidence level when adopting a mass-to-light ratio inferred from stellar populations. This is the fourth supermassive black hole found in a UCD and the first one in the Fornax cluster. Similarly to other known UCDs that harbour black holes, UCD3 hosts metal rich stars enhanced in α-elements that support the tidal stripping of a massive progenitor as its likely formation scenario. We estimate that up to 80 per cent of luminous UCDs in galaxy clusters host central black holes. This fraction should be lower for UCDs in groups, because their progenitors are more likely to be dwarf galaxies, which do not usually host black holes massive enough to be detected.
Abstract
We present 0.″22-resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations of CO(2−1) emission from the circumnuclear gas disk in the red nugget relic galaxy PGC 11179. The ...disk shows regular rotation, with projected velocities near the center of 400 km s
−1
. We assume the CO emission originates from a dynamically cold, thin disk and fit gas-dynamical models directly to the ALMA data. In addition, we explore systematic uncertainties by testing the impacts of various model assumptions on our results. The supermassive black hole (BH) mass (
M
BH
) is measured to be
M
BH
= (1.91 ± 0.04 1
σ
statistical
−
0.51
+
0.11
systematic) × 10
9
M
⊙
, and the
H
-band stellar mass-to-light ratio
M
/
L
H
= 1.620 ± 0.004 1
σ
statistical
−
0.107
+
0.211
systematic
M
⊙
/
L
⊙
. This
M
BH
is consistent with the BH mass−stellar velocity dispersion relation but over-massive compared to the BH mass−bulge luminosity relation by a factor of 3.7. PGC 11179 is part of a sample of local compact early-type galaxies that are plausible relics of
z
∼ 2 red nuggets, and its behavior relative to the scaling relations echoes that of three relic galaxy BHs previously measured with stellar dynamics. These over-massive BHs could suggest that BHs gain most of their mass before their host galaxies do. However, our results could also be explained by greater intrinsic scatter at the high-mass end of the scaling relations, or by systematic differences in gas- and stellar-dynamical methods. Additional
M
BH
measurements in the sample, including independent cross-checks between molecular gas- and stellar-dynamical methods, will advance our understanding of the co-evolution of BHs and their host galaxies.
Abstract
We present a stellar dynamical mass measurement of a newly detected supermassive black hole (SMBH) at the center of the fast-rotating, massive elliptical galaxy NGC 2693 as part of the ...MASSIVE survey. We combine high signal-to-noise ratio integral field spectroscopy (IFS) from the Gemini Multi-Object Spectrograph with wide-field data from the Mitchell Spectrograph at McDonald Observatory to extract and model stellar kinematics of NGC 2693 from the central ∼150 pc out to ∼2.5 effective radii. Observations from Hubble Space Telescope WFC3 are used to determine the stellar light distribution. We perform fully triaxial Schwarzschild orbit modeling using the latest TriOS code and a Bayesian search in 6D galaxy model parameter space to determine NGC 2693's SMBH mass (
M
BH
), stellar mass-to-light ratio, dark matter content, and intrinsic shape. We find
M
BH
=
1.7
±
0.4
×
10
9
M
⊙
and a triaxial intrinsic shape with axis ratios
p
=
b
/
a
= 0.902 ± 0.009 and
q
=
c
/
a
=
0.721
−
0.010
+
0.011
, triaxiality parameter
T
= 0.39 ± 0.04. In comparison, the best-fit orbit model in the axisymmetric limit and (cylindrical) Jeans anisotropic model of NGC 2693 prefer
M
BH
=
2.4
±
0.6
×
10
9
M
⊙
and
M
BH
=
2.9
±
0.3
×
10
9
M
⊙
, respectively. Neither model can account for the non-axisymmetric stellar velocity features present in the IFS data.
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