DYNAMICAL CONSTRAINTS ON THE MASSES OF THE NUCLEAR STAR CLUSTER AND BLACK HOLE IN THE LATE-TYPE SPIRAL GALAXY NGC 3621

Abstract Galaxies can grow through their mutual gravitational attraction and subsequent union. While orbiting a regular high-surface-brightness galaxy, the body of a low-mass galaxy can be stripped away. However, the stellar heart of the infalling galaxy, if represented by a tightly bound nuclear star cluster, is more resilient. From archival Hubble Space Telescope images, we have discovered a red, tidally stretched star cluster positioned ∼5″ (∼400 pc in projection) from, and pointing toward the center of, the post-merger spiral galaxy NGC 4424. The star cluster, which we refer to as “Nikhuli,” has a near-infrared luminosity of (6.88 ± 1.85) × 106 L ⊙,F160W and likely represents the nucleus of a captured/wedded galaxy. Moreover, from our Chandra X-ray Observatory image, Nikhuli is seen to contain a high-energy X-ray point source, with L 0.5 − 8 keV = 6.31 − 3.77 + 7.50 × 10 38 erg s−1 (90% confidence). We argue that this is more likely to be an active massive black hole than an X-ray binary. Lacking an outward-pointing comet-like appearance, the stellar structure of Nikhuli favors infall rather than the ejection from a gravitational-wave recoil event. A minor merger with a low-mass early-type galaxy may have sown a massive black hole, aided an X-shaped pseudobulge, and be sewing a small bulge. The stellar mass and the velocity dispersion of NGC 4424 predict a central black hole of (0.6–1.0) × 105 M ⊙, similar to the expected intermediate-mass black hole in Nikhuli, and suggestive of a black hole supply mechanism for bulgeless late-type galaxies. We may potentially be witnessing black hole seeding by capture and sinking, with a nuclear star cluster the delivery vehicle.

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Improved Dynamical Constraints on the Masses of the Central Black Holes in Nearby Low-mass Early-type Galactic Nuclei and the First Black Hole Determination for NGC 205

The Astrophysical Journal ◽

10.3847/1538-4357/aafe7a ◽

2019 ◽

Vol 872 (1) ◽

pp. 104 ◽

Cited By ~ 25

Author(s):

Dieu D. Nguyen ◽

Anil C. Seth ◽

Nadine Neumayer ◽

Satoru Iguchi ◽

Michelle Cappellari ◽

...

Keyword(s):

Black Holes ◽

Black Hole ◽

Galactic Nuclei ◽

Early Type ◽

Low Mass ◽

Dynamical Constraints ◽

The Masses

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Refining the mass estimate for the intermediate-mass black hole candidate in NGC 3319

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2021.23 ◽

2021 ◽

Vol 38 ◽

Author(s):

Benjamin L. Davis ◽

Alister W. Graham

Keyword(s):

Black Holes ◽

Black Hole ◽

Meta Analysis ◽

Rotational Velocity ◽

Logarithmic Spiral ◽

Star Cluster ◽

Black Hole Mass ◽

Intermediate Mass ◽

Mass Scaling ◽

Cluster Mass

Abstract Recent X-ray observations by Jiang et al. have identified an active galactic nucleus (AGN) in the bulgeless spiral galaxy NGC 3319, located just $14.3\pm 1.1$ Mpc away, and suggest the presence of an intermediate-mass black hole (IMBH; $10^2\leq M_\bullet/\textrm{M}_{\odot}\leq 10^5$ ) if the Eddington ratios are as high as 3 to $3\times10^{-3}$ . In an effort to refine the black hole mass for this (currently) rare class of object, we have explored multiple black hole mass scaling relations, such as those involving the (not previously used) velocity dispersion, logarithmic spiral arm pitch angle, total galaxy stellar mass, nuclear star cluster mass, rotational velocity, and colour of NGC 3319, to obtain 10 mass estimates, of differing accuracy. We have calculated a mass of $3.14_{-2.20}^{+7.02}\times10^4\,\textrm{M}_\odot$ , with a confidence of 84% that it is $\leq $ $10^5\,\textrm{M}_\odot$ , based on the combined probability density function from seven of these individual estimates. Our conservative approach excluded two black hole mass estimates (via the nuclear star cluster mass and the fundamental plane of black hole activity—which only applies to black holes with low accretion rates) that were upper limits of ${\sim}10^5\,{\textrm M}_{\odot}$ , and it did not use the $M_\bullet$ – $L_{\textrm 2-10\,\textrm{keV}}$ relation’s prediction of $\sim$ $10^5\,{\textrm M}_{\odot}$ . This target provides an exceptional opportunity to study an IMBH in AGN mode and advance our demographic knowledge of black holes. Furthermore, we introduce our novel method of meta-analysis as a beneficial technique for identifying new IMBH candidates by quantifying the probability that a galaxy possesses an IMBH.

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Toward Precision Measurement of Central Black Hole Masses

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310006095 ◽

2009 ◽

Vol 5 (S267) ◽

pp. 151-160 ◽

Cited By ~ 4

Author(s):

Bradley M. Peterson

Keyword(s):

Black Holes ◽

Black Hole ◽

Host Galaxy ◽

Reverberation Mapping ◽

Line Region ◽

The Masses ◽

The Relationship ◽

Black Hole Masses ◽

Intrinsic Scatter ◽

Direct And Indirect Methods

AbstractWe review briefly direct and indirect methods of measuring the masses of black holes in galactic nuclei, and then focus attention on supermassive black holes in active nuclei, with special attention to results from reverberation mapping and their limitations. We find that the intrinsic scatter in the relationship between the AGN luminosity and the broad-line region size is very small, ~0.11 dex, comparable to the uncertainties in the better reverberation measurements. We also find that the relationship between reverberation-based black hole masses and host-galaxy bulge luminosities also seems to have surprisingly little intrinsic scatter, ~0.17 dex. We note, however, that there are still potential systematics that could affect the overall mass calibration at the level of a factor of a few.

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Spectroscopy of H II regions in the late-type spiral galaxy NGC 6946

Astrophysical Bulletin ◽

10.1134/s1990341313010045 ◽

2013 ◽

Vol 68 (1) ◽

pp. 40-52 ◽

Cited By ~ 6

Author(s):

A. S. Gusev ◽

F. H. Sakhibov ◽

S. N. Dodonov

Keyword(s):

Spiral Galaxy ◽

H Ii Regions ◽

Late Type ◽

Ngc 6946

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An exceptional population of late-type WC stars in the metal-rich spiral galaxy M 83

Astronomy and Astrophysics ◽

10.1051/0004-6361:20040128 ◽

2004 ◽

Vol 419 (2) ◽

pp. L17-L20 ◽

Cited By ~ 9

Author(s):

P. A. Crowther ◽

L. J. Hadfield ◽

H. Schild ◽

W. Schmutz

Keyword(s):

Spiral Galaxy ◽

Late Type

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The imprint of arms and bars on rotation curves: in-plane and off-plane

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1677 ◽

2020 ◽

Vol 496 (2) ◽

pp. 1845-1856

Author(s):

Luis A Martinez-Medina ◽

Barbara Pichardo ◽

Antonio Peimbert

Keyword(s):

Spiral Galaxy ◽

Pitch Angle ◽

Local Minima ◽

Late Type ◽

Rotation Curves ◽

Spiral Arms ◽

Stellar Disc ◽

Secular Evolution ◽

Galaxy Model ◽

Characteristic Features

ABSTRACT Within rotation curves (RCs) is encoded the kinematical state of the stellar disc as well as information about the dynamical mechanisms driving the secular evolution of galaxies. To explain the characteristic features of RCs which arise by the influence of spiral patterns and bar, we study the kinematics of the stellar disc in a set of spiral galaxy models specifically tailored for this purpose. We find that, for our models, the induced non-circular motions are more prominent for spirals with larger pitch angle, the ones typical in late-type galaxies. Moreover, inside corotation, stars rotate slower along the spiral arms than along the interarm, which translates into a local minima or maxima in the RC, respectively. We also see, from off-plane RC, that the rotation is faster for stars that at observed closer to the plane, and diminishes as one looks farther off plane; this trend is more noticeable in our Sa galaxy model than our Sc galaxy model. Additionally, in a previous work we found that the diagonal ridges in the Vϕ–R plane, revealed through the GaiaDR2, have a resonant origin due to the spiral arms and bar and that these ridges project themselves as wiggles in the RC; here, we further notice that the development of these ridges, and the development of high orbital eccentricities in the stellar disc are the same. Hence, we conclude that, the following explanations of bumps and wiggles in RCs are equivalent: they are manifestations of diagonal ridges in the Vϕ–R plane, or of the rearrangement of the orbital eccentricities in the stellar disc.

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New Reverberation Mapping Results from the Lick AGN Monitoring Project

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310006174 ◽

2009 ◽

Vol 5 (S267) ◽

pp. 197-197

Author(s):

Misty C. Bentz ◽

Keyword(s):

Black Hole ◽

Reverberation Mapping ◽

Scaling Relationships ◽

Mapping Experiment ◽

The Masses ◽

Black Hole Masses

AbstractEight new black hole masses have been derived from a recent reverberation-mapping experiment carried out at Lick Observatory. The masses lie in the range ~ 106–107M⊙ and will allow us to extend the low end of AGN scaling relationships by a factor of ~10.

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