Dynamic property investigation of segmented acoustic black hole beam with different power-law thicknesses

2021 ◽  
Vol 30 (5) ◽  
pp. 055001
Author(s):  
Qidi Fu ◽  
Xiaofei Du ◽  
Jianwei Wu ◽  
Jianrun Zhang
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Dynamic Property

CAN WE DIFFERENTIATE NEUTRINOS FROM ANTI-NEUTRINOS IN EVOLUTION OF MASSLESS DIRAC FIELDS IN SCHWARZSCHILD BLACK-HOLE BACKGROUND?

2006 ◽  
Vol 21 (07) ◽  
pp. 593-601
Author(s):  
JILIANG JING
Keyword(s):  
Black Hole ◽  
Decay Rate ◽  
Power Law ◽  
Quasinormal Modes ◽  
Tail Behavior ◽  
Schwarzschild Black Hole ◽  
Dirac Fields ◽  
Black Hole Background ◽  
Opposite Chirality

We study analytically the evolution of massless Dirac fields in the background of the Schwarzschild black hole. It is shown that although the quasinormal frequencies are the same for opposite chirality with the same |k|, we can differentiate neutrinos from anti-neutrinos in evolution of the massless Dirac fields provided we know both stages for the quasinormal modes and the power-law tail behavior since the decay rate of the neutrinos is described by t-(2|k|+1) while anti-neutrinos is t-(2|k|+3).

scholarly journals Discovery of a New X-ray Transient in Scorpius GRO J1655-40 ≡ X-ray Nova Scorpii 1994

1996 ◽  
Vol 165 ◽  
pp. 363-367
Author(s):  
W.S. Paciesas ◽  
S.N. Zhang ◽  
B.C. Rubin ◽  
B.A. Harmon ◽  
C.A. Wilson ◽  
...  
Keyword(s):  
Black Hole ◽  
High Resolution ◽  
Power Law ◽  
Radio Observations ◽  
X Ray ◽  
Black Hole Candidate ◽  
Radio Jets ◽  
Transient Source ◽  
Galactic Source ◽  
Photon Index

A bright transient X-ray source, GRO J1655-40 (X-ray Nova Scorpii 1994) was discovered with BATSE (the Burst and Transient Source Experiment) in late July 1994. More recently, the source also became a strong radio emitter, its rise in the radio being approximately anti-correlated with a decline in the hard X-ray intensity. High-resolution radio observations subsequent to this symposium showed evidence for superluminally expanding jets. Since the hard X-ray emission extends to at least 200 keV and we find no evidence of pulsations, we tentatively classify the source as a black-hole candidate. However, its hard X-ray spectrum is unusually steep (power-law photon index α ≃ −3) relative to most other black-hole candidates. In this regard, it resembles GRS 1915+105, the first galactic source to show superluminal radio jets.

scholarly journals Third order quasitopological black hole with a power-law Maxwell nonlinear source

2019 ◽  
Vol 99 (2) ◽  
Author(s):  
M. Ghanaatian ◽  
F. Naeimipour ◽  
A. Bazrafshan ◽  
M. Eftekharian ◽  
A. Ahmadi
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Third Order ◽  
Nonlinear Source

scholarly journals Characterisation of the continuum and kinematical properties of nearby NLS1

2019 ◽  
Vol 629 ◽  
pp. A50
Author(s):  
Gabriel A. Oio ◽  
Luis R. Vega ◽  
Eduardo O. Schmidt ◽  
Diego Ferreiro
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Velocity Dispersion ◽  
Spectral Synthesis ◽  
Sloan Digital Sky Survey ◽  
Black Hole Mass ◽  
Composite Spectra ◽  
Sky Survey ◽  
Stellar Velocity ◽  
Gaussian Decomposition

Aims. In order to study the slope and strength of the non-stellar continuum, we analysed a sample from nearby Narrow Line Seyfert 1 (NLS1). Also, we re-examined the location of NLS1 galaxies on the MBH − σ⋆ relation, using the stellar velocity dispersion and the [OIII]λ5007 emission line as a surrogate of the former. Methods. We studied spectra of a sample of 131 NLS1 galaxies taken from the Sloan Digital Sky Survey (SDSS) DR7. We approached determining the non-stellar continuum by employing the spectral synthesis technique, which uses the code STARLIGHT, and by adopting a power-law base to model the non-stellar continuum. Composite spectra of NLS1 galaxies were also obtained based on the sample. In addition, we obtained the stellar velocity dispersion from the code and by measuring Calcium II Triplet absorption lines and [OIII] emission lines. From Gaussian decomposition of the Hβ profile we calculated the black hole mass. Results. We obtained a median slope of β = −1.6 with a median fraction of contribution of the non-stellar continuum to the total flux of 0.64. We determined black hole masses in the range of log(MBH/M⊙) = 5.6–7.5, which is in agreement with previous works. We found a correlation between the luminosity of the broad component of Hβ and black hole mass with the fraction of a power-law component. Finally, according to our results, NLS1 galaxies in our sample are located mostly underneath the MBH − σ⋆ relation, both considering the stellar velocity dispersion (σ⋆) and the core component of [OIII]λ5007.

scholarly journals THERMODYNAMICS OF A SCHWARZSCHILD BLACK HOLE IN PHANTOM COSMOLOGY WITH ENTROPY CORRECTIONS

2012 ◽  
Vol 21 (07) ◽  
pp. 1250065 ◽  
Author(s):  
MUBASHER JAMIL ◽  
D. MOMENI ◽  
KAZUHARU BAMBA ◽  
RATBAY MYRZAKULOV
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Phantom Energy ◽  
Upper Bounds ◽  
Quantum Corrections ◽  
Second Law ◽  
Schwarzschild Black Hole ◽  
Frw Universe ◽  
Generalized Second Law ◽  
Entropy Corrections

Motivated by some earlier works [G. Izquierdo and D. Pavon, Phys. Lett. B 639 (2006) 1; H. M. Sadjadi, Phys. Lett. B 645 (2007) 108.] dealing with the study of generalized second law (GSL) of thermodynamics for a system comprising of a Schwarzschild black hole accreting a test nonself-gravitating fluid namely phantom energy in FRW universe, we extend them when the entropy of horizons of black hole and the cosmological undergo quantum corrections. Two types of such corrections are relevant here including logarithmic and power-law, while both are motivated from different theoretical backgrounds. We obtain general mathematical conditions for the validity of GSL in each case. Further we find that GSL restricts the mass of black hole for accretion of phantom energy. As such we obtain upper bounds on the mass of black hole above which the black hole cannot accrete the phantom fluid, otherwise the GSL is violated.

scholarly journals Power law corrections to BTZ black hole entropy

2014 ◽  
Vol 24 (01) ◽  
pp. 1550001 ◽  
Author(s):  
Dharm Veer Singh
Keyword(s):  
Black Hole ◽  
Excited State ◽  
Power Law ◽  
Ground State ◽  
Entanglement Entropy ◽  
Black Hole Entropy ◽  
Mixed States ◽  
Btz Black Hole ◽  
First Excited State ◽  
Area Law

We study the quantum scalar field in the background of BTZ black hole and evaluate the entanglement entropy of the nonvacuum states. The entropy is proportional to the area of event horizon for the ground state, but the area law is violated in the case of nonvacuum states (first excited state and mixed states) and the corrections scale as power law.

scholarly journals Where are the degrees of freedom responsible for black-hole entropy?

2008 ◽  
Vol 86 (4) ◽  
pp. 653-658 ◽  
Author(s):  
S Das ◽  
S Shankaranarayanan ◽  
S Sur
Keyword(s):  
Black Hole ◽  
Excited State ◽  
Power Law ◽  
Ground State ◽  
Degrees Of Freedom ◽  
Black Hole Entropy ◽  
Quantum Field ◽  
Hole Area ◽  
Area Law ◽  
03.65 Ud

Considering the entanglement between quantum field degrees of freedom inside and outside the horizon as a plausible source of black-hole entropy, we address the question: where are the degrees of freedom that give rise to this entropy located? When the field is in ground state, the black-hole area law is obeyed and the degrees of freedom near the horizon contribute most to the entropy. However, for excited state, or a superposition of ground state and excited state, power-law corrections to the area law are obtained, and more significant contributions from the degrees of freedom far from the horizon are shown.PACS Nos.: 04.60.–m, 04.62., 04.70.–s, 03.65.Ud

scholarly journals Phase transition and geometrical thermodynamics of energy-dependent dilatonic BTZ black holes with power-law electrodynamics

2020 ◽  
Vol 2020 (3) ◽  
Author(s):  
M Dehghani ◽  
M Badpa
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Power Law ◽  
Scalar Potential ◽  
Standard Form ◽  
Three Dimensional ◽  
Nonlinear Electrodynamics ◽  
De Sitter ◽  
Field Equations ◽  
Energy Dependent

Abstract The coupled scalar, electromagnetic, and gravitational field equations of Einstein–dilaton gravity theory have been solved in a three-dimensional energy-dependent spacetime and in the presence of power-law nonlinear electrodynamics. The scalar potential is written as the linear combination of two exponential functions, and two families of three-dimensional dilatonic black hole solutions have been introduced which indicate the impacts of rainbow functions on the spacetime geometry. Through consideration of curvature scalars, it has been found that the asymptotic behavior of the solutions is neither flat nor anti-de Sitter. It has been illustrated that, with a suitable choice of parameters, the solutions can produce the two-horizon, extreme and naked singularity black holes. By calculating the black hole charge, mass, entropy, temperature, and electric potential, it has been proved that they fulfill the standard form of the first law of black hole thermodynamics. The thermodynamic stability of the black holes has been analyzed by utilizing the canonical and grand canonical ensembles and noting the signature of the black hole heat capacity and Gibbs free energy of the black holes. The points of type-1, type-2, and Hawking–Page phase transitions and the ranges at which the black holes are locally or globally stable have been determined. The geometrical thermodynamics of the black holes has been studied by use of different thermodynamic metrics, and the results of different approaches have been compared.

scholarly journals X-ray and optical observations of the black hole candidate MAXI J1828−249

2019 ◽  
Vol 71 (5) ◽  
Author(s):  
Sonoe Oda ◽  
Megumi Shidatsu ◽  
Satoshi Nakahira ◽  
Toru Tamagawa ◽  
Yuki Moritani ◽  
...  
Keyword(s):  
Black Hole ◽  
Low Temperature ◽  
Power Law ◽  
Spectral Power ◽  
Spectral Energy Distribution ◽  
Disk Surface ◽  
Optical Observations ◽  
Spectral Energy ◽  
X Ray ◽  
Black Hole Candidate

Abstract We report results from X-ray and optical observations of the Galactic black hole candidate MAXI J1828−249 performed with Suzaku and the Kanata telescope around the X-ray flux peak in the 2013 outburst. The time-averaged X-ray spectrum covering 0.6–168 keV was approximately characterized by a strong multi-color disk blackbody component with an inner disk temperature of ∼0.6 keV, and a power-law tail with a photon index of ∼2.0. We detected an additional structure at 5–10 keV, which can be modeled neither with X-ray reflection on the disk nor relativistic broadening of the disk emission. Instead, it was successfully reproduced with a Comptonization of disk photons by thermal electrons with a relatively low temperature (≲10 keV). We infer that the source was in the intermediate state, considering its long-term trend in the hardness intensity diagram, the strength of the spectral power-law tail, and its variability properties. The low-temperature Comptonization component could be produced in a boundary region between the truncated standard disk and the hot inner flow, or a Comptonizing region that somehow developed above the disk surface. The multi-wavelength spectral energy distribution suggests that the optical and ultraviolet fluxes were dominated by irradiated outer disk emission.

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