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.

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.

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.

GLOBULAR CLUSTERS HOSTING INTERMEDIATE-MASS BLACK HOLES: NO MASS-SEGREGATION BASED CANDIDATES

2016 ◽  
Vol 823 (2) ◽  
pp. 135 ◽  
Author(s):  
Mario Pasquato ◽  
Paolo Miocchi ◽  
Sohn Bong Won ◽  
Young-Wook Lee
Keyword(s):  
Black Holes ◽  
Globular Clusters ◽  
Intermediate Mass ◽  
Mass Segregation ◽  
Intermediate Mass Black Holes

scholarly journals Observational evidence for intermediate-mass black holes

2017 ◽  
Vol 26 (11) ◽  
pp. 1730021 ◽  
Author(s):  
Mar Mezcua
Keyword(s):  
Black Holes ◽  
Galaxy Formation ◽  
Globular Clusters ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Observational Evidence ◽  
Intermediate Mass ◽  
X Ray ◽  
Mass Scaling ◽  
Intermediate Mass Black Holes

Intermediate-mass black holes (IMBHs), with masses in the range [Formula: see text]–[Formula: see text][Formula: see text]M[Formula: see text], are the link between stellar-mass BHs and supermassive BHs (SMBHs). They are thought to be the seeds from which SMBHs grow, which would explain the existence of quasars with BH masses of up to 10[Formula: see text][Formula: see text]M[Formula: see text] when the Universe was only 0.8 Gyr old. The detection and study of IMBHs has thus strong implications for understanding how SMBHs form and grow, which is ultimately linked to galaxy formation and growth, as well as for studies of the universality of BH accretion or the epoch of reionization. Proving the existence of seed BHs in the early Universe is not yet feasible with the current instrumentation; however, those seeds that did not grow into SMBHs can be found as IMBHs in the nearby Universe. In this review, I summarize the different scenarios proposed for the formation of IMBHs and gather all the observational evidence for the few hundreds of nearby IMBH candidates found in dwarf galaxies, globular clusters, and ultraluminous X-ray sources, as well as the possible discovery of a few seed BHs at high redshift. I discuss some of their properties, such as X-ray weakness and location in the BH mass scaling relations, and the possibility to discover IMBHs through high velocity clouds, tidal disruption events, gravitational waves, or accretion disks in active galactic nuclei. I finalize with the prospects for the detection of IMBHs with up-coming observatories.

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 On the coexistence of stellar-mass and intermediate-mass black holes in globular clusters

2014 ◽  
Vol 444 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Nathan W. C. Leigh ◽  
Nora Lützgendorf ◽  
Aaron M. Geller ◽  
Thomas J. Maccarone ◽  
Craig Heinke ◽  
...  
Keyword(s):  
Black Holes ◽  
Globular Clusters ◽  
Stellar Mass ◽  
Intermediate Mass ◽  
Intermediate Mass Black Holes
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