High Mass but Low Spin: An Exclusion Region to Rule Out Hierarchical Black Hole Mergers as a Mechanism to Populate the Pair-instability Mass Gap

Abstract We investigate the presence of a central black hole (BH) in B023-G078, M31's most massive globular cluster. We present high-resolution, adaptive-optics assisted, integral-field spectroscopic kinematics from Gemini/NIFS that show a strong rotation (∼20 km s−1) and a velocity dispersion rise toward the center (37 km s−1). We combine the kinematic data with a mass model based on a two-component fit to HST ACS/HRC data of the cluster to estimate the mass of a putative BH. Our dynamical modeling suggests a >3σ detection of a BH component of 9.1 − 2.8 + 2.6 × 10 4 M ⊙ (1σ uncertainties). The inferred stellar mass of the cluster is 6.22 − 0.05 + 0.03 × 10 6 M ⊙ , consistent with previous estimates, thus the BH makes up 1.5% of its mass. We examine whether the observed kinematics are caused by a collection of stellar mass BHs by modeling an extended dark mass as a Plummer profile. The upper limit on the size scale of the extended mass is 0.56 pc (95% confidence), which does not rule out an extended mass. There is compelling evidence that B023-G078 is the tidally stripped nucleus of a galaxy with a stellar mass >109 M ⊙, including its high-mass, two-component luminosity profile, color, metallicity gradient, and spread in metallicity. Given the emerging evidence that the central BH occupation fraction of >109 M ⊙ galaxies is high, the most plausible interpretation of the kinematic data is that B023-G078 hosts a central BH. This makes it the strongest BH detection in a lower-mass (<107 M ⊙) stripped nucleus, and one of the few dynamically detected intermediate-mass BHs.

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Not so fast: LB-1 is unlikely to contain a 70 M⊙ black hole

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slaa004 ◽

2020 ◽

Vol 493 (1) ◽

pp. L22-L27 ◽

Cited By ~ 19

Author(s):

Kareem El-Badry ◽

Eliot Quataert

Keyword(s):

Black Hole ◽

Radial Velocity ◽

Emission Line ◽

Absorption Line ◽

Relative Velocity ◽

Stellar Mass ◽

Accretion Disc ◽

High Mass ◽

Mass Ratio ◽

Rule Out

ABSTRACT The recently discovered binary LB-1 has been reported to contain a ${\sim }70\, \mathrm{M}_{\odot}$ black hole (BH). The evidence for the unprecedentedly high mass of the unseen companion comes from reported radial velocity (RV) variability of the H α emission line, which has been proposed to originate from an accretion disc around a BH. We show that there is in fact no evidence for RV variability of the H α emission line, and that its apparent shifts instead originate from shifts in the luminous star’s H α absorption line. If not accounted for, such shifts will cause a stationary emission line to appear to shift in antiphase with the luminous star. We show that once the template spectrum of a B star is subtracted from the observed Keck/HIRES spectra of LB-1, evidence for RV variability vanishes. Indeed, the data rule out periodic variability of the line with velocity semi-amplitude $K_{\rm H\,\alpha } \gt 1.3\, {\rm {km}} \, s^{-1}$. This strongly suggests that the observed H α emission does not originate primarily from an accretion disc around a BH, and thus that the mass ratio cannot be constrained from the relative velocity amplitudes of the emission and absorption lines. The nature of the unseen companion remains uncertain, but a ‘normal’ stellar-mass BH with mass 5 ≲ M/M⊙ ≲ 20 seems most plausible. The H α emission likely originates primarily from circumbinary material, not from either component of the binary.

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Morphological evolution of supermassive black hole merger hosts and multimessenger signatures

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab721 ◽

2021 ◽

Vol 503 (3) ◽

pp. 3629-3642

Author(s):

Colin DeGraf ◽

Debora Sijacki ◽

Tiziana Di Matteo ◽

Kelly Holley-Bockelmann ◽

Greg Snyder ◽

...

Keyword(s):

Black Holes ◽

Black Hole ◽

Star Formation ◽

Morphological Evolution ◽

Full Range ◽

High Mass ◽

Morphological Evidence ◽

Galaxy Mergers ◽

Host Galaxies ◽

Supermassive Black Hole

ABSTRACT With projects such as Laser Interferometer Space Antenna (LISA) and Pulsar Timing Arrays (PTAs) expected to detect gravitational waves from supermassive black hole mergers in the near future, it is key that we understand what we expect those detections to be, and maximize what we can learn from them. To address this, we study the mergers of supermassive black holes in the Illustris simulation, the overall rate of mergers, and the correlation between merging black holes and their host galaxies. We find these mergers occur in typical galaxies along the MBH−M* relation, and that between LISA and PTAs we expect to probe the full range of galaxy masses. As galaxy mergers can trigger star formation, we find that galaxies hosting low-mass black hole mergers tend to show a slight increase in star formation rates compared to a mass-matched sample. However, high-mass merger hosts have typical star formation rates, due to a combination of low gas fractions and powerful active galactic nucleus feedback. Although minor black hole mergers do not correlate with disturbed morphologies, major mergers (especially at high-masses) tend to show morphological evidence of recent galaxy mergers which survive for ∼500 Myr. This is on the same scale as the infall/hardening time of merging black holes, suggesting that electromagnetic follow-ups to gravitational wave signals may not be able to observe this correlation. We further find that incorporating a realistic time-scale delay for the black hole mergers could shift the merger distribution towards higher masses, decreasing the rate of LISA detections while increasing the rate of PTA detections.

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Observational manifestations of ‘cosmological dinosaurs’ at redshifts z ∼ 20

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab689 ◽

2021 ◽

Vol 503 (2) ◽

pp. 3081-3088

Author(s):

V K Dubrovich ◽

Yu N Eroshenko ◽

S I Grachev

Keyword(s):

Black Hole ◽

Atomic Hydrogen ◽

Radiation Transfer ◽

Ring Width ◽

High Mass ◽

Primordial Black Hole ◽

Array Type ◽

Local Sources ◽

Order Of Magnitude ◽

Very High

ABSTRACT We consider a primordial black hole of very high mass, $10^9\!-\!10^{10}\, \mathrm{M}_\odot$, surrounded by the dark matter and bayonic halo at redshifts z ∼ 20 without any local sources of energy release. Such heavy and concentrated objects in the early Universe were previously called ‘cosmological dinosaurs’. Spectral distribution and spatial variation of the brightness in the 21-cm line of atomic hydrogen are calculated with the theory of radiation transfer. It is shown that a narrow and deep absorption arises in the form of the spherical shell around the primordial black hole at the certain radius. The parameters of this shell depend almost exclusively on the mass of the black hole. The angular diameter 18 arcsec of the absorption ring at z ∼ 20 is well within the current technical possibilities of the Square Kilometre Array type telescopes. But the observation of the ring width itself requires an order of magnitude better resolution.

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Black hole, neutron star, and white dwarf merger rates in AGN discs

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2681 ◽

2020 ◽

Vol 498 (3) ◽

pp. 4088-4094 ◽

Cited By ~ 4

Author(s):

B McKernan ◽

K E S Ford ◽

R O’Shaughnessy

Keyword(s):

Black Hole ◽

Compact Object ◽

Relative Number ◽

Expected Number ◽

Lower Mass ◽

Strong Function ◽

Mass Gap ◽

Mass Segregation ◽

The Hill ◽

Mass Functions

ABSTRACT Advanced LIGO and Advanced Virgo are detecting a large number of binary stellar origin black hole (BH) mergers. A promising channel for accelerated BH merger lies in active galactic nucleus (AGN) discs of gas around supermasssive BHs. Here, we investigate the relative number of compact object (CO) mergers in AGN disc models, including BH, neutron stars (NS), and white dwarfs, via Monte Carlo simulations. We find the number of all merger types in the bulk disc grows ∝ t1/3 which is driven by the Hill sphere of the more massive merger component. Median mass ratios of NS–BH mergers in AGN discs are $\tilde{q}=0.07\pm 0.06(0.14\pm 0.07)$ for mass functions (MF) M−1(− 2). If a fraction fAGN of the observed rate of BH–BH mergers (RBH–BH) come from AGN, the rate of NS–BH (NS–NS) mergers in the AGN channel is ${R}_{\mathrm{ BH}\!-\!\mathrm{ NS}} \sim f_{\mathrm{ AGN}}[10,300]\, \rm {Gpc}^{-3}\, \rm {yr}^{-1},({\mathit{ R}}_{NS\!-\!NS} \le \mathit{ f}_{AGN}400\, \rm {Gpc}^{-3}\, \rm {yr}^{-1}$). Given the ratio of NS–NS/BH–BH LIGO search volumes, from preliminary O3 results the AGN channel is not the dominant contribution to observed NS–NS mergers. The number of lower mass gap events expected is a strong function of the nuclear MF and mass segregation efficiency. CO merger ratios derived from LIGO can restrict models of MF, mass segregation, and populations embedded in AGN discs. The expected number of electromagnetic (EM) counterparts to NS–BH mergers in AGN discs at z < 1 is $\sim [30,900]\, {\rm {yr}}^{-1}(f_{\mathrm{ AGN}}/0.1)$. EM searches for flaring events in large AGN surveys will complement LIGO constraints on AGN models and the embedded populations that must live in them.

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Sensitivity of the lower edge of the pair-instability black hole mass gap to the treatment of time-dependent convection

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa549 ◽

2020 ◽

Vol 493 (3) ◽

pp. 4333-4341 ◽

Cited By ~ 16

Author(s):

M Renzo ◽

R J Farmer ◽

S Justham ◽

S E de Mink ◽

Y Götberg ◽

...

Keyword(s):

Black Hole ◽

Gravitational Wave ◽

Time Scale ◽

Turnover Time ◽

Black Hole Mass ◽

The Third ◽

Mass Gap ◽

Mixing Length Theory ◽

State Assumption ◽

Additional Equation

ABSTRACT Gravitational-wave detections are now probing the black hole (BH) mass distribution, including the predicted pair-instability mass gap. These data require robust quantitative predictions, which are challenging to obtain. The most massive BH progenitors experience episodic mass ejections on time-scales shorter than the convective turnover time-scale. This invalidates the steady-state assumption on which the classic mixing length theory relies. We compare the final BH masses computed with two different versions of the stellar evolutionary code $\tt{MESA}$: (i) using the default implementation of Paxton et al. (2018) and (ii) solving an additional equation accounting for the time-scale for convective deceleration. In the second grid, where stronger convection develops during the pulses and carries part of the energy, we find weaker pulses. This leads to lower amounts of mass being ejected and thus higher final BH masses of up to ∼$5\, \mathrm{M}_\odot$. The differences are much smaller for the progenitors that determine the maximum mass of BHs below the gap. This prediction is robust at $M_{\rm BH, max}\simeq 48\, \mathrm{M}_\odot$, at least within the idealized context of this study. This is an encouraging indication that current models are robust enough for comparison with the present-day gravitational-wave detections. However, the large differences between individual models emphasize the importance of improving the treatment of convection in stellar models, especially in the light of the data anticipated from the third generation of gravitational-wave detectors.

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Constraining the stellar mass function from the deficiency of tidal disruption flares in the nuclei of massive galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz652 ◽

2019 ◽

Vol 485 (3) ◽

pp. 4413-4422 ◽

Cited By ~ 1

Author(s):

Daniel J D’Orazio ◽

Abraham Loeb ◽

James Guillochon

Keyword(s):

Black Hole ◽

Mass Function ◽

Stellar Mass ◽

High Mass ◽

Black Hole Mass ◽

Tidal Disruption ◽

Massive Black Hole ◽

Massive Black Holes ◽

Massive Galaxies ◽

O 10

ABSTRACT The rate of tidal disruption flares (TDFs) per mass of the disrupting black hole encodes information on the present-day mass function (PDMF) of stars in the clusters surrounding super massive black holes. We explore how the shape of the TDF rate with black hole mass can constrain the PDMF, with only weak dependence on black hole spin. We show that existing data can marginally constrain the minimum and maximum masses of stars in the cluster, and the high-mass end of the PDMF slope, as well as the overall TDF rate. With $\mathcal {O}(100)$ TDFs expected to be identified with the Zwicky Transient Facility, the overall rate can be highly constrained, but still with only marginal constraints on the PDMF. However, if ${\lesssim } 10 {{\ \rm per\ cent}}$ of the TDFs expected to be found by LSST over a decade ($\mathcal {O}(10^3)$ TDFs) are identified, then precise and accurate estimates can be made for the minimum stellar mass (within a factor of 2) and the average slope of the high-mass PDMF (to within $\mathcal {O}(10{{\ \rm per\ cent}})$) in nuclear star clusters. This technique could be adapted in the future to probe, in addition to the PDMF, the local black hole mass function and possibly the massive black hole binary population.

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Mass transfer on a nuclear timescale in models of supergiant and ultra-luminous X-ray binaries

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935453 ◽

2019 ◽

Vol 628 ◽

pp. A19 ◽

Cited By ~ 6

Author(s):

M. Quast ◽

N. Langer ◽

T. M. Tauris

Keyword(s):

Mass Transfer ◽

Black Hole ◽

Neutron Star ◽

Roche Lobe ◽

High Mass ◽

X Rays ◽

X Ray ◽

Mass Ratios ◽

X Ray Binaries ◽

Eddington Limit

Context. The origin and number of the Galactic supergiant X-ray binaries is currently not well understood. They consist of an evolved massive star and a neutron star or black-hole companion. X-rays are thought to be generated from the accretion of wind material donated by the supergiant, while mass transfer due to Roche-lobe overflow is mostly disregarded because the high mass ratios of these systems are thought to render this process unstable. Aims. We investigate how the proximity of supergiant donor stars to the Eddington limit, and their advanced evolutionary stage, may influence the evolution of massive and ultra-luminous X-ray binaries with supergiant donor stars (SGXBs and ULXs). Methods. We constructed models of massive stars with different internal hydrogen and helium gradients (H/He gradients) and different hydrogen-rich envelope masses, and exposed them to slow mass-loss to probe the response of the stellar radius. In addition, we computed the corresponding Roche-lobe overflow mass-transfer evolution with our detailed binary stellar evolution code, approximating the compact objects as point masses. Results. We find that a H/He gradient in the layers beneath the surface, as it is likely present in the well-studied donor stars of observed SGBXs, can enable mass transfer in SGXBs on a nuclear timescale with a black-hole or a neutron star accretor, even for mass ratios in excess of 20. In our binary evolution models, the donor stars rapidly decrease their thermal equilibrium radius and can therefore cope with the inevitably strong orbital contraction imposed by the high mass ratio. We find that the orbital period derivatives of our models agree well with empirical values. We argue that the SGXB phase may be preceded by a common-envelope evolution. The envelope inflation near the Eddington limit means that this mechanism more likely occurs at high metallicity. Conclusion. Our results open a new perspective for understanding that SGBXs are numerous in our Galaxy and are almost completely absent in the Small Magellanic Cloud. Our results may also offer a way to find more ULX systems, to detect mass transfer on nuclear timescales in ULX systems even with neutron star accretors, and shed new light on the origin of the strong B-field in these neutron stars.

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High-Mass X-ray Binaries: progenitors of double compact objects

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319001315 ◽

2018 ◽

Vol 14 (S346) ◽

pp. 1-13

Author(s):

Edward P. J. van den Heuvel

Keyword(s):

Black Holes ◽

Black Hole ◽

Neutron Stars ◽

Compact Objects ◽

High Mass ◽

X Ray ◽

Future Evolution ◽

Short Period ◽

Orbital Periods ◽

X Ray Binaries

AbstractA summary is given of the present state of our knowledge of High-Mass X-ray Binaries (HMXBs), their formation and expected future evolution. Among the HMXB-systems that contain neutron stars, only those that have orbital periods upwards of one year will survive the Common-Envelope (CE) evolution that follows the HMXB phase. These systems may produce close double neutron stars with eccentric orbits. The HMXBs that contain black holes do not necessarily evolve into a CE phase. Systems with relatively short orbital periods will evolve by stable Roche-lobe overflow to short-period Wolf-Rayet (WR) X-ray binaries containing a black hole. Two other ways for the formation of WR X-ray binaries with black holes are identified: CE-evolution of wide HMXBs and homogeneous evolution of very close systems. In all three cases, the final product of the WR X-ray binary will be a double black hole or a black hole neutron star binary.

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A ROBUST TEST OF GENERAL RELATIVITY IN SPACE

International Journal of Modern Physics D ◽

10.1142/s0218271807011401 ◽

2007 ◽

Vol 16 (12a) ◽

pp. 2319-2324 ◽

Cited By ~ 1

Author(s):

JAMES GRABER

Keyword(s):

Black Holes ◽

General Relativity ◽

Black Hole ◽

Quadrupole Moment ◽

Binary Systems ◽

High Mass ◽

Uniqueness Theorems ◽

Mass Ratio ◽

Intermediate Mass ◽

Robust Test

LISA may make it possible to test the black-hole uniqueness theorems of general relativity, also called the no-hair theorems, by Ryan's method of detecting the quadrupole moment of a black hole using high-mass-ratio inspirals. This test can be performed more robustly by observing inspirals in earlier stages, where the simplifications used in making inspiral predictions by the perturbative and post-Newtonian methods are more nearly correct. Current concepts for future missions such as DECIGO and BBO would allow even more stringent tests by this same method. Recently discovered evidence supports the existence of intermediate-mass black holes (IMBHs). Inspirals of binary systems with one IMBH and one stellar-mass black hole would fall into the frequency band of proposed maximum sensitivity for DECIGO and BBO. This would enable us to perform the Ryan test more precisely and more robustly. We explain why tests based on observations earlier in the inspiral are more robust and provide preliminary estimates of possible optimal future observations.

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