Understanding the dynamical status of Galactic Globular Cluster NGC 6656

2019 ◽  
Vol 14 (S351) ◽  
pp. 512-515
Author(s):  
Gaurav Singh ◽  
R. K. S. Yadav
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Density Profile ◽  
Globular Cluster ◽  
Stellar Mass ◽  
Horizontal Branch ◽  
Inner Region ◽  
Branch Morphology

AbstractWe present the study of horizontal branch morphology of the cluster NGC 6656. A blueward shift in temperature of about ~5000 K (nM-jump) in the color-color plot is detected.To explain this feature, we study the presence of stellar-mass black hole by plotting Projected density profile (PDP) in the central HST region. The PDP in the inner region (r < 10″) can be nicely reproduced by the king+BH model. The blue ward shift in temperature can be due the presence of stellar mass black holes in the centre.

scholarly journals A supra-massive population of stellar-mass black holes in the globular cluster Palomar 5

2021 ◽  
Author(s):  
Mark Gieles ◽  
Denis Erkal ◽  
Fabio Antonini ◽  
Eduardo Balbinot ◽  
Jorge Peñarrubia
Keyword(s):  
Black Holes ◽  
Globular Cluster ◽  
Stellar Mass

scholarly journals Probing black hole accretion tracks, scaling relations, and radiative efficiencies from stacked X-ray active galactic nuclei

2019 ◽  
Vol 493 (1) ◽  
pp. 1500-1511 ◽  
Author(s):  
Francesco Shankar ◽  
David H Weinberg ◽  
Christopher Marsden ◽  
Philip J Grylls ◽  
Mariangela Bernardi ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Selection Bias ◽  
Stellar Mass ◽  
Supermassive Black Holes ◽  
Independent Evidence ◽  
X Ray ◽  
Black Hole Accretion ◽  
Black Hole Masses ◽  
Hole Accretion

ABSTRACT The masses of supermassive black holes at the centres of local galaxies appear to be tightly correlated with the mass and velocity dispersions of their galactic hosts. However, the local Mbh–Mstar relation inferred from dynamically measured inactive black holes is up to an order-of-magnitude higher than some estimates from active black holes, and recent work suggests that this discrepancy arises from selection bias on the sample of dynamical black hole mass measurements. In this work, we combine X-ray measurements of the mean black hole accretion luminosity as a function of stellar mass and redshift with empirical models of galaxy stellar mass growth, integrating over time to predict the evolving Mbh–Mstar relation. The implied relation is nearly independent of redshift, indicating that stellar and black hole masses grow, on average, at similar rates. Matching the de-biased local Mbh–Mstar relation requires a mean radiative efficiency ε ≳ 0.15, in line with theoretical expectations for accretion on to spinning black holes. However, matching the ‘raw’ observed relation for inactive black holes requires ε ∼ 0.02, far below theoretical expectations. This result provides independent evidence for selection bias in dynamically estimated black hole masses, a conclusion that is robust to uncertainties in bolometric corrections, obscured active black hole fractions, and kinetic accretion efficiency. For our fiducial assumptions, they favour moderate-to-rapid spins of typical supermassive black holes, to achieve ε ∼ 0.12–0.20. Our approach has similarities to the classic Soltan analysis, but by using galaxy-based data instead of integrated quantities we are able to focus on regimes where observational uncertainties are minimized.

scholarly journals The astrophysical odds of GW151216

2020 ◽  
Vol 498 (2) ◽  
pp. 1905-1910 ◽  
Author(s):  
Gregory Ashton ◽  
Eric Thrane
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Wave ◽  
Bayesian Method ◽  
Massive Stars ◽  
Stellar Mass ◽  
Population Analyses ◽  
Wave Detection ◽  
Binary Black Hole ◽  
Bona Fide

ABSTRACT The gravitational-wave candidate GW151216 is a proposed binary black hole event from the first observing run of the Advanced LIGO detectors. Not identified as a bona fide signal by the LIGO–Virgo collaboration, there is disagreement as to its authenticity, which is quantified by pastro, the probability that the event is astrophysical in origin. Previous estimates of pastro from different groups range from 0.18 to 0.71, making it unclear whether this event should be included in population analyses, which typically require pastro &gt; 0.5. Whether GW151216 is an astrophysical signal or not has implications for the population properties of stellar-mass black holes and hence the evolution of massive stars. Using the astrophysical odds, a Bayesian method that uses the signal coherence between detectors and a parametrized model of non-astrophysical detector noise, we find that pastro = 0.03, suggesting that GW151216 is unlikely to be a genuine signal. We also analyse GW150914 (the first gravitational-wave detection) and GW151012 (initially considered to be an ambiguous detection) and find pastro values of 1 and 0.997, respectively. We argue that the astrophysical odds presented here improve upon traditional methods for distinguishing signals from noise.

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 &gt; 0.5 M⊙, main-sequence stars with a (1D) velocity v &gt; 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 &gt; 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.

scholarly journals Multivariate analysis of globular cluster horizontal branch morphology: searching for the second parameter

2006 ◽  
Vol 452 (3) ◽  
pp. 875-884 ◽  
Author(s):  
A. Recio-Blanco ◽  
A. Aparicio ◽  
G. Piotto ◽  
F. De Angeli ◽  
S. G. Djorgovski
Keyword(s):  
Multivariate Analysis ◽  
Globular Cluster ◽  
Horizontal Branch ◽  
Branch Morphology

scholarly journals Comparing the birth rate of stellar black holes in binary black hole mergers and long gamma-ray bursts

2018 ◽  
Vol 610 ◽  
pp. A58
Author(s):  
J.-L. Atteia ◽  
J.-P. Dezalay ◽  
O. Godet ◽  
A. Klotz ◽  
D. Turpin ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Birth Rate ◽  
Gamma Ray ◽  
Reference Model ◽  
Stellar Mass ◽  
Gamma Ray Bursts ◽  
Birth Rates ◽  
Binary Black Hole ◽  
History Of

Context. Gravitational wave interferometers have proven the existence of a new class of binary black hole (BBH) weighing tens of solar masses, and have provided the first reliable measurement of the rate of coalescing black holes (BHs) in the local Universe. Furthermore, long gamma-ray bursts (GRBs) detected with gamma-ray satellites are believed to be associated with the birth of stellar-mass BHs, providing a measure of the rate of these events across the history of the Universe, thanks to the measure of their cosmological redshift. These two types of sources, which are subject to different detection biases and involve BHs born in different environments with potentially different characteristics, provide complementary information on the birth rate of stellar BHs. Aims. We compare the birth rates of BHs found in BBH mergers and in long GRBs. Methods. We construct a simple model that makes reasonable assumptions on the history of GRB formation, and takes into account some major uncertainties, like the beaming angle of GRBs or the delay between the formation of BBHs and their coalescence. We use this model to evaluate the ratio of the number of stellar mass BHs formed in BBH mergers to those formed in GRBs. Results. We find that in our reference model the birth rate of stellar BHs in BBH mergers represents a significant fraction of the rate of long GRBs and that comparable birth rates are favored by models with moderate beaming angles. These numbers, however, do not consider subluminous GRBs, which may represent another population of sources associated with the birth of stellar mass BHs. We briefly discuss this result in view of our understanding of the progenitors of GRBs and BBH mergers, and we emphasize that this ratio, which will be better constrained in the coming years, can be directly compared with the prediction of stellar evolution models if a single model is used to produce GRBs and BBH mergers with the same assumptions.

scholarly journals Observational evidence for stellar-mass black holes

2006 ◽  
Vol 2 (S238) ◽  
pp. 3-12 ◽  
Author(s):  
Jorge Casares
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Mass Spectrum ◽  
Radial Velocity ◽  
Stellar Mass ◽  
Observational Evidence ◽  
X Ray ◽  
History Of ◽  
X Ray Binaries ◽  
Dynamical Masses

AbstractRadial velocity studies of X-ray binaries provide the most solid evidence for the existence of stellar-mass black holes. We currently have 20 confirmed cases, with dynamical masses in excess of 3 M⊙. Accurate masses have been obtained for a subset of systems which gives us a hint at the mass spectrum of the black hole population. This review summarizes the history of black hole discoveries and presents the latest results in the field.

scholarly journals VVV SURVEY OBSERVATIONS OF A MICROLENSING STELLAR MASS BLACK HOLE CANDIDATE IN THE FIELD OF THE GLOBULAR CLUSTER NGC 6553

2015 ◽  
Vol 810 (2) ◽  
pp. L20 ◽  
Author(s):  
D. Minniti ◽  
R. Contreras Ramos ◽  
J. Alonso-García ◽  
T. Anguita ◽  
M. Catelan ◽  
...  
Keyword(s):  
Black Hole ◽  
Globular Cluster ◽  
Stellar Mass ◽  
Black Hole Candidate

scholarly journals Ultralight bosons for strong gravity applications from simple Standard Model extensions

2021 ◽  
Vol 2021 (12) ◽  
pp. 047
Author(s):  
Felipe F. Freitas ◽  
Carlos A.R. Herdeiro ◽  
António P. Morais ◽  
António Onofre ◽  
Roman Pasechnik ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Mass Spectrum ◽  
Standard Model ◽  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Mass Range ◽  
Stellar Mass ◽  
Compact Objects ◽  
The Standard Model

Abstract We construct families, and concrete examples, of simple extensions of the Standard Model that can yield ultralight real or complex vectors or scalars with potential astrophysical relevance. Specifically, the mass range for these putative fundamental bosons (∼ 10-10-10-20 eV) would lead dynamically to both new non-black hole compact objects (bosonic stars) and new non-Kerr black holes, with masses of ∼ M⊙ to ∼ 1010 M⊙, corresponding to the mass range of astrophysical black hole candidates (from stellar mass to supermassive). For each model, we study the properties of the mass spectrum and interactions after spontaneous symmetry breaking, discuss its theoretical viability and caveats, as well as some of its potential and most relevant phenomenological implications linking them to the physics of compact objects.

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