scholarly journals Intermediate-mass black holes in globular clusters: observations and simulations - Update

2015 ◽  
Vol 12 (S316) ◽  
pp. 240-245
Author(s):  
Nora Lützgendorf ◽  
Markus Kissler-Patig ◽  
Karl Gebhardt ◽  
Holger Baumgardt ◽  
Diederik Kruijssen ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Globular Clusters ◽  
Galactic Center ◽  
Early Stage ◽  
Life Time ◽  
Intermediate Mass ◽  
Software Environment ◽  
Integral Field ◽  
Intermediate Mass Black Holes

AbstractThe study of intermediate-mass black holes (IMBHs) is a young and promising field of research. If IMBH exist, they could explain the rapid growth of supermassive black holes by acting as seeds in the early stage of galaxy formation. Formed by runaway collisions of massive stars in young and dense stellar clusters, intermediate-mass black holes could still be present in the centers of globular clusters, today. We measured the inner kinematic profiles with integral-field spectroscopy for 10 Galactic globular cluster and determined masses or upper limits of central black holes. In combination with literature data we further studied the positions of our results on known black-hole scaling relations (such as M• − σ) and found a similar but flatter correlation for IMBHs. Applying cluster evolution codes, the change in the slope could be explained with the stellar mass loss occurring in clusters in a tidal field over its life time. Furthermore, we present results from several numerical simulations on the topic of IMBHs and integral field units (IFUs). N-body simulations were used to simulate IFU data cubes. For the specific case of NGC 6388 we simulated two different IFU techniques and found that velocity dispersion measurements from individual velocities are strongly biased towards lower values due to blends of neighbouring stars and background light. In addition, we use the Astrophysical Multipurpose Software Environment (AMUSE) to combine gravitational physics, stellar evolution and hydrodynamics to simulate the accretion of stellar winds onto a black hole. We find that the S-stars need to provide very strong winds in order to explain the accretion rate in the galactic center.

scholarly journals Intermediate-mass black holes in globular clusters: observations and simulations

2014 ◽  
Vol 10 (S312) ◽  
pp. 181-188
Author(s):  
Nora Lützgendorf ◽  
Markus Kissler-Patig ◽  
Karl Gebhardt ◽  
Holger Baumgardt ◽  
Diederik Kruijssen ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Mass Loss ◽  
Globular Clusters ◽  
Early Stage ◽  
Life Time ◽  
Intermediate Mass ◽  
Software Environment ◽  
Integral Field ◽  
Intermediate Mass Black Holes

AbstractThe study of intermediate-mass black holes (IMBHs) is a young and promising field of research. If IMBHs exist, they could explain the rapid growth of supermassive black holes by acting as seeds in the early stage of galaxy formation. Formed by runaway collisions of massive stars in young and dense stellar clusters, intermediate-mass black holes could still be present in the centers of globular clusters, today. Our group investigated the presence of intermediate-mass black holes for a sample of 10 Galactic globular clusters. We measured the inner kinematic profiles with integral-field spectroscopy and determined masses or upper limits of central black holes in each cluster. In combination with literature data we further studied the positions of our results on known black-hole scaling relations (such as M• − σ) and found a similar but flatter correlation for IMBHs. Applying cluster evolution codes, the change in the slope could be explained with the stellar mass loss occurring in clusters in a tidal field over its life time. Furthermore, we present results from several numerical simulations on the topic of IMBHs and integral field units (IFUs). We ran N-body simulations of globular clusters containing IMBHs in a tidal field and studied their effects on mass-loss rates and remnant fractions and showed that an IMBH in the center prevents core collapse and ejects massive objects more rapidly. These simulations were further used to simulate IFU data cubes. For the specific case of NGC 6388 we simulated two different IFU techniques and found that velocity dispersion measurements from individual velocities are strongly biased towards lower values due to blends of neighboring stars and background light. In addition, we use the Astrophysical Multipurpose Software Environment (AMUSE) to combine gravitational physics, stellar evolution and hydrodynamics to simulate the accretion of stellar winds onto a black hole.

Intermediate-mass black holes in globular clusters: constraints on the spin of a black hole

Astrophysics ◽  
2011 ◽  
Vol 54 (4) ◽  
pp. 548-552 ◽  
Author(s):  
S. D. Buliga ◽  
V. I. Globina ◽  
Yu. N. Gnedin ◽  
T. M. Natsvlishvili ◽  
M. Yu. Piotrovich ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Globular Clusters ◽  
Intermediate Mass ◽  
Intermediate Mass Black Holes

scholarly journals mocca-survey Database I: Binary black hole mergers from globular clusters with intermediate mass black holes

2020 ◽  
Vol 498 (3) ◽  
pp. 4287-4294
Author(s):  
Jongsuk Hong ◽  
Abbas Askar ◽  
Mirek Giersz ◽  
Arkadiusz Hypki ◽  
Suk-Jin Yoon
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Waves ◽  
Globular Clusters ◽  
Stellar Mass ◽  
Intermediate Mass ◽  
Binary Black Holes ◽  
Black Hole Binaries ◽  
Binary Black Hole ◽  
Intermediate Mass Black Holes

ABSTRACT The dynamical formation of black hole binaries in globular clusters that merge due to gravitational waves occurs more frequently in higher stellar density. Meanwhile, the probability to form intermediate mass black holes (IMBHs) also increases with the density. To explore the impact of the formation and growth of IMBHs on the population of stellar mass black hole binaries from globular clusters, we analyse the existing large survey of Monte Carlo globular cluster simulation data (mocca-survey Database I). We show that the number of binary black hole mergers agrees with the prediction based on clusters’ initial properties when the IMBH mass is not massive enough or the IMBH seed forms at a later time. However, binary black hole formation and subsequent merger events are significantly reduced compared to the prediction when the present-day IMBH mass is more massive than ${\sim}10^4\, \rm M_{\odot }$ or the present-day IMBH mass exceeds about 1 per cent of cluster’s initial total mass. By examining the maximum black hole mass in the system at the moment of black hole binary escaping, we find that ∼90 per cent of the merging binary black holes escape before the formation and growth of the IMBH. Furthermore, large fraction of stellar mass black holes are merged into the IMBH or escape as single black holes from globular clusters in cases of massive IMBHs, which can lead to the significant underpopulation of binary black holes merging with gravitational waves by a factor of 2 depending on the clusters’ initial distributions.

scholarly journals Eccentric binary black hole mergers in globular clusters hosting intermediate-mass black holes

2019 ◽  
Vol 488 (3) ◽  
pp. 4370-4377 ◽  
Author(s):  
Giacomo Fragione ◽  
Omer Bromberg
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Globular Clusters ◽  
Dynamical Friction ◽  
Intermediate Mass ◽  
Triple Systems ◽  
Binary Black Hole ◽  
Binary Orbit ◽  
Short Time ◽  
Intermediate Mass Black Holes

Abstract Globular clusters (GCs) may harbour intermediate-mass black holes (IMBHs) at their centres. In these dynamically active environments, stellar-mass black holes (SBHs) sink to the centre soon after formation, due to dynamical friction and start interacting among themselves and with the central IMBH. Likely, some of the SBHs will form bound systems with the IMBH. A fraction of those will be triple systems composed of binary SBHs and the IMBH acting as a third distant perturber. If the SBH binary orbit is sufficiently inclined, it can develop Lidov–Kozai (LK) oscillations, which can drive the system to high eccentricities and eventually to a merger due to gravitational wave (GW) emission on short time-scales. In this work, we focus on the dynamics of the IMBH–SBH–SBH triples and illustrate that these systems can be possible sources of GWs. A distinctive signature of this scenario is that a considerable fraction of these mergers are highly eccentric when entering the LIGO band (10 Hz). Assuming that $\sim 20{{\ \rm per\ cent}}$ of GCs host IMBHs and a GC density in the range $n_{{\rm GC}}=0.32\!-\!2.31\, \mathrm{Mpc}^{-3}$, we have estimated a rate $\Gamma =0.06\!-\!0.46\, \mathrm{Gpc}^{-3}\, \mathrm{yr}^{-1}$ of these events. This suggests that dynamically driven binary SBH mergers in this scenario could contribute to the merger events observed by LIGO/VIRGO. Full N-body simulations of GCs harbouring IMBHs are highly desirable to give a more precise constrain on this scenario.

scholarly journals Searching for intermediate mass black holes: understanding the data first

2014 ◽  
Vol 10 (S312) ◽  
pp. 223-226
Author(s):  
Paolo Bianchini ◽  
Mark Norris ◽  
Glenn van de Ven ◽  
Eva Schinnerer
Keyword(s):  
Black Holes ◽  
Globular Clusters ◽  
Velocity Dispersion ◽  
Data Cube ◽  
Intermediate Mass ◽  
Integral Field Spectroscopy ◽  
Kinematic Measurement ◽  
Intrinsic Scatter ◽  
Integral Field ◽  
Intermediate Mass Black Holes

AbstractThe detection of intermediate mass black holes (IMBHs) in globular clusters has been hotly debated, with different observational methods delivering different outcomes for the same object. In order to understand these discrepancies, we construct detailed mock integral field spectroscopy (IFU) observations of globular clusters, starting from realistic Monte Carlo cluster simulations. The output is a data cube of spectra in a given field-of-view that can be analyzed in the same manner as real observations and compared to other (resolved) kinematic measurement methods. We show that the main discrepancies arise because the luminosity-weighted IFU observations can be strongly biased by the presence of a few bright stars that introduce a scatter in velocity dispersion measurements of several km s−1. We show that this intrinsic scatter can prevent a sound assessment of the central kinematics, and therefore should be fully taken into account to correctly interpret the signature of an IMBH.

Binary Black Hole Merger: Mass-Separation Relation and Intermediate Mass Black Holes

2020 ◽  
Author(s):  
Kushaal Kumar Pothula
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Globular Clusters ◽  
Mass Range ◽  
Mass Separation ◽  
Intermediate Mass ◽  
Binary Black Hole ◽  
Separation Relation ◽  
Hubble Time ◽  
Intermediate Mass Black Holes

Abstract Intermediate Mass Black Holes (IMBHs) are an elusive category of black holes in the mass range of 100 to 100000 Solar Masses. Binary IMBHs might form due to mergers of Globular Clusters, Pair Instability Supernovae, and in Young Massive Star Clusters. In this Research Note, merger timescale, constraints on the separation based on the timescale, and other parameters of Binary IMBHs are calculated analytically and are discussed. The calculations were conducted using Newtonian and Einstienian dynamics. The timescale of a Binary IMBH system to reach maximum gravitational wave amplitude is also calculated ad discussed. We also present the relation between the combined Mass of a Binary Black Hole (BBH) System and the Separation between two BHs required for a BBH system to merge within a given timescale tc, solely due to Gravitational Radiation is a function of the total mass of the system. In this article, tc is set equal to Hubble time tH. Now, the relation obtained is essentially the relation between separation of a BBH system (collide within tH) and its Mass. The calculations were conducted for all three categories of Black Holes: Stellar, Intermediate, and Supermassive. Time ahead, the relation might be used for determining whether a BBH merger would be observational. The relation is also solved for Intermediate Mass Black Holes (IMBHs), and and tc separation for collision within tH was calculated.

scholarly journals Intermediate-Mass Black Holes

2020 ◽  
Vol 58 (1) ◽  
pp. 257-312 ◽  
Author(s):  
Jenny E. Greene ◽  
Jay Strader ◽  
Luis C. Ho
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Globular Clusters ◽  
High Redshift ◽  
Mass Function ◽  
Intermediate Mass ◽  
The Galaxy ◽  
Robust Measurements ◽  
Black Hole Masses ◽  
Intermediate Mass Black Holes

We describe ongoing searches for intermediate-mass black holes with MBH ≈ 10–105 M⊙. We review a range of search mechanisms, both dynamical and those that rely on accretion signatures. We find the following conclusions: ▪  Dynamical and accretion signatures alike point to a high fraction of 109–1010 M⊙ galaxies hosting black holes with MBH∼ 105 M⊙. In contrast, there are no solid detections of black holes in globular clusters. ▪  There are few observational constraints on black holes in any environment with MBH ≈ 100–104 M⊙. ▪  Considering low-mass galaxies with dynamical black hole masses and constraining limits, we find that the MBH–σ* relation continues unbroken to MBH ∼105 M⊙, albeit with large scatter. We believe the scatter is at least partially driven by a broad range in black hole masses, because the occupation fraction appears to be relatively high in these galaxies. ▪  We fold the observed scaling relations with our empirical limits on occupation fraction and the galaxy mass function to put observational bounds on the black hole mass function in galaxy nuclei. ▪  We are pessimistic that local demographic observations of galaxy nuclei alone could constrain seeding mechanisms, although either high-redshift luminosity functions or robust measurements of off-nuclear black holes could begin to discriminate models.

scholarly journals No evidence for intermediate-mass black holes in the globular clusters ω Cen and NGC 6624

2019 ◽  
Vol 488 (4) ◽  
pp. 5340-5351 ◽  
Author(s):  
H Baumgardt ◽  
C He ◽  
S M Sweet ◽  
M Drinkwater ◽  
A Sollima ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Velocity Dispersion ◽  
Stellar Mass ◽  
Main Sequence Stars ◽  
Intermediate Mass ◽  
Measured Velocity ◽  
Large Grid

ABSTRACT We compare the results of a large grid of N-body simulations with the surface brightness and velocity dispersion profiles of the globular clusters ω Cen and NGC 6624. Our models include clusters with varying stellar-mass black hole retention fractions and varying masses of a central intermediate-mass black hole (IMBH). We find that an $\sim 45\, 000$ M⊙ IMBH, whose presence has been suggested based on the measured velocity dispersion profile of ω Cen, predicts the existence of about 20 fast-moving, m > 0.5 M⊙, main-sequence stars with a (1D) velocity v > 60 km s−1 in the central 20 arcsec of ω Cen. However, no such star is present in the HST/ACS proper motion catalogue of Bellini et al. (2017), strongly ruling out the presence of a massive IMBH in the core of ω Cen. Instead, we find that all available data can be fitted by a model that contains 4.6 per cent of the mass of ω Cen in a centrally concentrated cluster of stellar-mass black holes. We show that this mass fraction in stellar-mass BHs is compatible with the predictions of stellar evolution models of massive stars. We also compare our grid of N-body simulations with NGC 6624, a cluster recently claimed to harbour a 20 000 M⊙ black hole based on timing observations of millisecond pulsars. However, we find that models with MIMBH > 1000 M⊙ IMBHs are incompatible with the observed velocity dispersion and surface brightness profile of NGC 6624, ruling out the presence of a massive IMBH in this cluster. Models without an IMBH provide again an excellent fit to NGC 6624.

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