scholarly journals Testing the Kerr black hole hypothesis with the continuum-fitting and the iron line methods: the case of GRS 1915+105

2022 ◽  
Vol 2022 (01) ◽  
pp. 019
Author(s):  
Ashutosh Tripathi ◽  
Askar B. Abdikamalov ◽  
Dimitry Ayzenberg ◽  
Cosimo Bambi ◽  
Victoria Grinberg ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Deformation Parameter ◽  
Kerr Black Hole ◽  
Stellar Mass ◽  
Kerr Metric ◽  
Iron Line ◽  
Strong Gravity ◽  
The Continuum

Abstract The continuum-fitting and the iron line methods are currently the two leading techniques for probing the strong gravity region around accreting black holes. In the present work, we test the Kerr black hole hypothesis with the stellar-mass black hole in GRS 1915+105 by analyzing five disk-dominated RXTE spectra and one reflection-dominated Suzaku spectrum. The combination of the constraints from the continuum-fitting and the iron line methods has the potential to provide more stringent tests of the Kerr metric. Our constraint on the Johannsen deformation parameter α13 is -0.15 < α13 < 0.14 at 3σ, where the Kerr metric is recovered when α13 = 0.

scholarly journals Testing the Kerr Black Hole Hypothesis with GRS 1716-249 by Combining the Continuum Fitting and the Iron-line Methods

2022 ◽  
Vol 924 (2) ◽  
pp. 72
Author(s):  
Zuobin Zhang ◽  
Honghui Liu ◽  
Askar B. Abdikamalov ◽  
Dimitry Ayzenberg ◽  
Cosimo Bambi ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
State Of The Art ◽  
Kerr Black Hole ◽  
Thermal Component ◽  
Fundamental Physics ◽  
Iron Line ◽  
The Past ◽  
Black Hole Binary ◽  
The Continuum

Abstract The continuum-fitting and the iron-line methods are currently the two leading techniques for measuring the spins of accreting black holes. In the past few years, these two methods have been developed for testing fundamental physics. In the present work, we employ state-of-the-art models to test black holes through the continuum-fitting and the iron-line methods and we analyze three NuSTAR observations of the black hole binary GRS 1716-249 during its outburst in 2016–2017. In these three observations, the source was in a hard-intermediate state and the spectra show both a strong thermal component and prominent relativistic reflection features. Our analysis confirms the Kerr nature of the black hole in GRS 1716-249 and provides quite stringent constraints on possible deviations from the predictions of general relativity.

Extremal Kerr Black Holes, Naked Singularity & Wormholes

2020 ◽  
Author(s):  
Deep Bhattacharjee
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Angular Momentum ◽  
Event Horizon ◽  
Kerr Black Hole ◽  
Naked Singularity ◽  
Kerr Metric ◽  
Spin Angular Momentum ◽  
The Way

This paper is totally based on the mathematical physics of the Black holes. In Einstein’s theory of “General Relativity”, Schwarzschild solution is the vacuum solutions of the Einstein Field Equations that describes the gravity potential from outside the body of a spherically symmetric object having zero charge, zero mass and zero cosmological constant[1]. It was discovered by Karl Schwarzschild in 1916, a little more than a month after the publication of the famous GR and the singularity is a point singularity which can be best described as a coordinate singularity rather than a real singularity, however, the drawback of this theory is that it fails to take into account the real life scenario of black holes with charge and spin angular momentum. The black hole is based on event horizon and Schwarzschild radius. However, Physicists were trying to develop a metric for the real life scenario of a black hole with a spin angular momen-tum and ultimately the exact solution of a charged rotating black hole had been discovered by Roy Kerr in 1965 as the Kerr-Newman metric[2][3]. The Kerr metric is one of the toughest metric in physics and is the extensional generalization to a rotating body of the Schwarzschild metric. The metric describes the vacuum geometry of space-time around a rotating axially-symmetric black hole with a quasipotential event horizon. In Kerr metric there are two event hori-zons (inner and outer), two ergospheres and an ergosurface. The most important effect of the Kerr metric is the frame dragging (also known as Lense-Thirring Precession) is a distinctive prediction of General relativity. The first direct observation of the collision of two Kerr Black Holes has been discovered by LIGO in 2016 hence setting up a milestone of General Relativity in the history of Physics. Here, the Kerr metric has been introduced in the Boyer-Lindquist forms and it is derived from the Schwarzschild metric using the Spin-Coefficient formalism. According to the “Cosmic Censorship Hypothesis”, a naked singularity cannot exist in nature as nature always hides the singularity via an event horizon. However, in this paper I will prove the existence of the “Naked Singularity" taking the advantage of the Ring Singularity of the Kerr Black Hole and thereby making the way to manipulate the mathematics by taking the larger root of Δ as zero and thereby vanishing the ergosphere and event horizon making the way for the naked ring singularity which can be easily connected via a cylindrical wormhole and as ‘a wormhole is a black hole without an event horizon’ therefore, this cylindrical connection paved the way for the Einstein-Rosen Bridge allowing particles or null rays to travel from one universe to another ending up in a future directed Cauchy horizon while changing constantly from spatial to temporal and again spatial paving the entrance to another Kerr Black hole (which would act as a white hole) in the other universes. I will not go in detail about the contradiction of ‘Chronology Protection Conjecture” [4]whether the Stress-Energy-Momentum Tensor can violate the ANEC (Average Null Energy Conditions) or not with the values of less than zero or greater than, equal to zero, instead I will focus definitely on the creation of the mathematical formulation of a wormhole from a Naked Ring Kerr Singularity of a Kerr Black Hole without any event horizon or ergosphere. Another important thing to mention in this paper is that I have taken the time to be imaginary[5] as because, a singularity being an eternal point of time can only be smoothen out if the time is imaginary rather than real which will allow the particle or null rays inside a wormhole to cross the singularity and making entrance to the other universe. The final conclusion would be to determine the mass-energy equivalence principle as spin angular momentum increases with a decrease in BH mass due to the vanishing event horizon and ergosphere thereby maintaining the equivalence via apparent and absolute masses in relation to spin J along the orthogonal Z axis. A ‘NAKED SINGULARITY’ alters every parameters of a BH and to include this parameters along with affine spin coefficient, it has been proved that without any spin angular momentum the generation of wormhole and vanishing of event horizon and singularity is not possible.

scholarly journals Quasi-periodic oscillations around Kerr-MOG black holes

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
Martin Kološ ◽  
Misbah Shahzadi ◽  
Zdeněk Stuchlík
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
High Frequency ◽  
Stellar Mass ◽  
Tidal Disruption ◽  
Periodic Oscillations ◽  
X Ray ◽  
Strong Gravity ◽  
Modified Theory Of Gravity ◽  
Modified Theory

Abstract The study of the quasi-periodic oscillations (QPOs) of X-ray flux observed in the stellar-mass black hole (BH) binaries can provide a powerful tool for testing the phenomena occurring in strong gravity regime. We thus present and apply to three known microquasars the model of epicyclic oscillations of Keplerian discs orbiting rotating BHs governed by the modified theory of gravity (MOG). We show that the standard geodesic models of QPOs can explain the observationally fixed data from the three microquasars, GRO 1655-40, XTE 1550-564, and GRS 1915+105. We perform a successful fitting of the high frequency (HF) QPOs observed in these microquasars, under assumption of MOG BHs, for epicyclic resonance and its variants, relativistic precession and its variants, tidal disruption, as well as warped disc models and discuss the corresponding constraints of parameters of the model, which are the mass and spin and parameter $$\alpha $$α of the BH.

scholarly journals Statistical Properties of Kerr BH Flywheel Model of QSOs/AGNs

2000 ◽  
Vol 195 ◽  
pp. 417-418
Author(s):  
S. Nitta
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Kerr Black Hole ◽  
Mass Function ◽  
Initial Mass Function ◽  
Number Density ◽  
Disk System ◽  
The Press ◽  
The Individual ◽  
Density Population

The aim of this work is to demonstrate the properties of the magnetospheric model around Kerr black holes, so-called the “flywheel” (rotation powered) model. The fly-wheel engine of the BH accretion disk system is applied to the statistics of QSOs/AGNs. Nitta, Takahashi, & Tomimatsu clarified the individual evolution of the Kerr black-hole fly-wheel engine, which is parameterized by black-hole mass, initial Kerr parameter, magnetic field near the horizon, and a dimensionless small parameter. We impose a statistical model for the initial mass function of an ensemble of black holes using the Press-Schechter formalism. With the help of additional assumptions, we can discuss the evolution of the luminosity function and the spatial number density (population) of QSOs/AGNs. The result explains well the decrease of very bright QSOs and decrease of population after z ~ 2.

Bound orbits around modified Hayward black holes

2021 ◽  
Author(s):  
Bo Gao ◽  
Xue-Mei Deng
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Gravitational Field ◽  
Periodic Orbits ◽  
Kerr Black Hole ◽  
Periodic Oscillations ◽  
Test Particles ◽  
Spin Parameter ◽  
Bound Orbits

The neutral time-like particle’s bound orbits around modified Hayward black holes have been investigated. We find that both in the marginally bound orbits (MBO) and the innermost stable circular orbits (ISCO), the test particle’s radius and its angular momentum are all more sensitive to one of the parameters [Formula: see text]. Especially, modified Hayward black holes with [Formula: see text] could mimic the same ISCO radius around the Kerr black hole with the spin parameter up to [Formula: see text]. Small [Formula: see text] could mimic the ISCO of small-spinning test particles around Schwarzschild black holes. Meanwhile, rational (periodic) orbits around modified Hayward black holes have also been studied. The epicyclic frequencies of the quasi-circular motion around modified Hayward black holes are calculated and discussed with respect to the observed Quasi-periodic oscillations (QPOs) frequencies. Our results show that rational orbits around modified Hayward black holes have different values of the energy from the ones of Schwarzschild black holes. The epicyclic frequencies in modified Hayward black holes have different frequencies from Schwarzschild and Kerr ones. These might provide hints for distinguishing modified Hayward black holes from Schwarzschild and Kerr ones by using the dynamics of time-like particles around the strong gravitational field.

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 Evidence for Strong Gravity in the AGN Plasmas

1998 ◽  
Vol 188 ◽  
pp. 141-144
Author(s):  
K. Iwasawa
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Relativistic Effects ◽  
Iron Line ◽  
X Ray ◽  
Strong Gravity

X-ray spectroscopy of the broad iron line has revealed some relativistic effects caused by strong gravity about a black hole in active galactic nuclei (AGN). Recent results from ASCA observations of AGNs are reviewed.

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.

Effect of charge and deformation parameter on energy extraction in charged non-Kerr black holes

2019 ◽  
Vol 28 (16) ◽  
pp. 2040012
Author(s):  
Rehana Rahim ◽  
Khalid Saifullah
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Deformation Parameter ◽  
High Efficiency ◽  
Process Efficiency ◽  
Energy Extraction ◽  
Penrose Process ◽  
Kerr Black Holes ◽  
Very High

We analyze the charged Johannsen–Psaltis black hole for energy extraction via the Penrose process. Efficiency of the Penrose process is found to be dependent on the deformation parameter of the metric and charge. Doing the calculations numerically, we find that, in the nonextremal limit, presence of charge leads to lesser efficiency than the Kerr. In the extremal cases with negative deformation parameter, charge leads to a very high efficiency, higher than that of the Kerr and Johannsen–Psaltis black holes.

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