News Release on Black Holes Research: April -2019

Hair distributions in noncommutative Einstein-Born-Infeld black holes

We study hair mass distributions in noncommutative Einstein-Born-Infeld bushy black holes with non-zero cosmological constants. we discover that the larger noncommutative parameter makes the hair easier to condense within the close to horizon space. we tend to additionally show that Hod’s bound are often evaded within the noncommutative gravity. However, for big black holes with a non-negative constant, Hod’s lower hair mass sure almost holds within the sense that almost 1/2 the hair lays higher than the photonsphere. [1]

Excited Kerr black holes with scalar hair

In the context of a posh field coupled to Einstein gravity theory, we tend to gift a completely unique family of solutions of Kerr black holes with excited state scalar hair impressed by the work of Herdeiro and Radu in [Phys. Rev. Lett. 112, 221101 (2014)], which might be considered numerical solutions of rotating compact objects with excited scalar hair, as well as particle stars and black holes. In distinction to Kerr black holes with state scalar hair, we discover that the primary excited Kerr black holes with scalar hair have 2 forms of nodes, as well as radial nr=1 and angular nθ=1 nodes. Moreover, within the case of each nodes the curves of the mass versus the frequency type nontrivial loops. what is more, we tend to conjointly show the numerical results of the second excited states with even parity, and notice that the curves are often divided into 2 kinds: closed and open loops. we tend to conjointly study the dependence of the horizon space on momentum and Hawking temperature in these excited states. [2]

Weighing Black Holes Using Tidal Disruption Events

While once rare, observations of stars being tidally discontinuous  by supermassive black holes are quickly changing into commonplace. To still learn from these events, it’s necessary to robustly and consistently compare our growing variety of observations with theory. we tend to gift a periodic event disruption module for the standard Open supply Fitter for Transients (MOSFiT) and also the results from fitting fourteen tidal disruption events (TDEs). Our model uses FLASH simulations of TDEs to get measuring system luminosities and passes these luminosities through consistency and reprocessing transformation functions to make multiwavelength light-weight curves. It then uses associate degree MCMC fitting routine to match these theoretical light-weight curves with observations. we discover that none of the events show proof for viscous delays olympian some days, supporting the speculation that our current observant methods within the optical/UV are missing a major variety of viscously delayed flares. We find that the events have black hole masses of 106–108 M  and that the masses we predict are as reliable as those based on bulk galaxy properties. We also find that there is a preference for stars with mass <1 M , as expected when low-mass stars greatly outnumber high-mass stars. [3]

Observing black holes spin

The spin of a region retains the memory of however the black hole grew, and may be a potent supply of energy for powering relativistic jets. to grasp the diagnostic power and uranology significance of region spin, however, we tend to should initial devise experimental ways for activity spin. Here, I describe this state of region spin measurements, highlight the progress created by X-ray astronomers, similarly because the current excitement of gravitative wave- and radio astronomy-based techniques. Today’s spin measurements are already constrictive models for the expansion of supermassive black holes and giving new insights into the dynamics of stellar core collapse, similarly as hinting at the physics of relativistic jet production. Future X-ray, radio and gravitative wave observatories can rework region spin into a exactitude tool for astronomy and check basic theories of gravity. [4]

Characteristics of Non-spinning Black Holes

Aims: To derive an expression for the wavelength/frequency of Hawking radiation emitted by non-spinning black holes in terms of the radius of event horizon (λ=8πRs & vc/8πRs) using quantum theory of radiation (Ehv) energy of Hawking radiation and the radius of event horizon of non-spinning black holes (Rs =2GM/c2), which may be regarded as the characteristics of non-spinning black holes.

Study Design: Data for the frequencies and wavelengths of Hawking radiation emitted from black holes have been calculated with the help of rest masses for stellar – mass black holes (M ~ 5 ­ 20 Mʘ) in X-ray binaries and for the super massive black holes (M ~ 106 – 109.5 Mʘ) in active galactic nuclei using λ=8πRs & v= c/8πRs which corresponds to the research work entitled: Frequency of Hawking radiation from black holes by Mahto et al. in International Journal of Astrophysics and Space Science (Dec. 2013).

Place and Duration of Study: Department of Physics, Marwari College under University Department of Physics, T.M.B.U. Bhagalpur between January 2014 and June 2014.

Methodology: It is completely theoretical based work using Laptop done at Marwari College Bhagalpur and the residential research chamber of the first author.

Results: The astrophysical objects emitting the radiations of frequencies (8.092×102Hz to 2.023×102Hz) or wavelengths (3.707×105m to 14.828×105m) in X-ray binaries and frequencies (4.046×10-3Hz to 0.809×10-6Hz) or wavelengths (7.414×1010m to 37.070×1013m) in active galactic nuclei may be classified as non-spinning black holes.

Conclusion: The frequencies or wavelengths of Hawking radiation emitted from non-spinning black holes may be regarded as the characteristics of black holes in addition to the mass, spin and charge. [5]

 

Reference

[1] Peng, Y., 2019. Hair distributions in noncommutative Einstein-Born-Infeld black holes. Nuclear Physics B941, pp.1-10 (Web Link)

[2] Wang, Y.Q., Liu, Y.X. and Wei, S.W., 2019. Excited Kerr black holes with scalar hair. Physical Review D99(6), p.064036. (Web Link)

[3] Mockler, B., Guillochon, J. and Ramirez-Ruiz, E., 2019. Weighing Black Holes Using Tidal Disruption Events. The Astrophysical Journal872(2), p.151. (Web Link)

[4] Observing black holes spin

Christopher S. Reynolds
Nature Astronomy volume 3, pages 41–47 (2019) (Web Link)

[5] Characteristics of Non-spinning Black Holes

Dipo Mahto
partment of Physics, Marwari College, T.M.B.U., Bhagalpur, India.

Brajesh Kumar Jha
University Department of Physics, L.N.M.U., Darbhanga, India.

Murlidhar Prasad Singh
Department of Physics, B.N.M. College, Barhiya, T.M.B.U., Bhagalpur, India

Promod Jha
Department of Physics, C.M. Science College, L.N.M.U., Darbhanga, India. (Web Link)

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