scholarly journals Inner structure of black holes in Eddington-inspired Born-Infeld gravity: The role of mass inflation

2016 ◽  
Vol 93 (4) ◽  
Author(s):  
P. P. Avelino
Keyword(s):  
Black Holes ◽  
Mass Inflation

scholarly journals Black hole and neutron star mergers in galactic nuclei: the role of triples

2019 ◽  
Vol 488 (2) ◽  
pp. 2825-2835 ◽  
Author(s):  
Giacomo Fragione ◽  
Nathan W C Leigh ◽  
Rosalba Perna
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Star ◽  
Massive Stars ◽  
Star Clusters ◽  
Galactic Nuclei ◽  
Compact Objects ◽  
Large Numbers ◽  
Binary Case

ABSTRACT Nuclear star clusters that surround supermassive black holes (SMBHs) in galactic nuclei are thought to contain large numbers of black holes (BHs) and neutron stars (NSs), a fraction of which form binaries and could merge by Kozai–Lidov oscillations (KL). Triple compact objects are likely to be present, given what is known about the multiplicity of massive stars, whose life ends either as an NS or a BH. In this paper, we present a new possible scenario for merging BHs and NSs in galactic nuclei. We study the evolution of a triple black hole (BH) or neutron star (NS) system orbiting an SMBH in a galactic nucleus by means of direct high-precision N-body simulations, including post-Newtonian terms. We find that the four-body dynamical interactions can increase the KL angle window for mergers compared to the binary case and make BH and NS binaries merge on shorter time-scales. We show that the merger fraction can be up to ∼5–8 times higher for triples than for binaries. Therefore, even if the triple fraction is only ∼10–$20\rm{\,per\,cent}$ of the binary fraction, they could contribute to the merger events observed by LIGO/VIRGO in comparable numbers.

scholarly journals The energetic role of massive stars in the AGN phenomenon

1999 ◽  
Vol 193 ◽  
pp. 703-715
Author(s):  
Timothy M. Heckman
Keyword(s):  
Black Holes ◽  
Massive Stars ◽  
Uv Light ◽  
Radiant Energy ◽  
Supermassive Black Holes ◽  
High Mass ◽  
Continuum Emission ◽  
Hot Stars

I review the evidence for a possible connection between AGN and starbursts and assess the energetic role of massive stars in the AGN phenomenon. My particular focus is on UV spectroscopy, since this is the energetically dominant spectral regime for the hot high-mass stars that power starbursts, and contains a wealth of spectral features for diagnosing the presence of such stars. I also review the non-stellar sources of UV line and continuum emission in AGN, including scattered or reprocessed light from the ‘central engine’. Spectroscopy directly shows that hot stars provide most of the UV light in about half of the brightest type 2 Seyfert nuclei and UV-bright LINERS. The population of hot stars in these AGN is typically heavily extinct and reddened by dust with A(1600Å) ≃ 2–4 mag. The implied intrinsic UV luminosities of the starburst range from 108 to 109 L⊙ in the LINERS to 1010 to 1011 L⊙ in the type 2 Seyferts. Massive stars play an energetically significant role in many AGN, but the causal or evolution connection between starbursts and AGN is unclear. I also consider the energetics of massive stars and accreting supermassive black holes from a global, cosmic perspective. Recent inventories in the local universe of the cumulative effect of nuclear burning (metal production) and of AGN-fueling (compact dark objects in galactic nuclei) imply that accretion onto supermassive black holes may have produced as much radiant energy as massive stars over the history of the universe.

scholarly journals Violation of the Dominant Energy Condition in Geometrodynamics

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 400
Author(s):  
Vladimir Lasukov
Keyword(s):  
Black Holes ◽  
Dark Energy ◽  
Energy Condition ◽  
Dominant Energy Condition ◽  
Isotropic Energy ◽  
Cosmological Singularity ◽  
Dominant Condition ◽  
Field Theoretical Model ◽  
Over Time

It is shown that in Einstein’s theory and in the theory of gravity with Logunov constraints, there is a field-theoretical model of dark energy that is consistent with the observational data indicating that the Hubble value increases over time. In the developed model of dark energy, the isotropic energy dominant condition is violated. It solves the problem of the cosmological singularity and the singularity of “black holes”. The compact configuration of the scalar field can generate a flux of particles by the pairs of particles production mechanism from the vacuum by a field of barrier and in the process of transformation of thermal energy (Hawking radiation) and acceleration energy into radiation. The scalars can play the role of the so-called “black holes” with no singularity inside themselves.

scholarly journals The Role of Gas Fragmentation During the Formation of Supermassive Black Holes

2019 ◽  
Vol 885 (2) ◽  
pp. 127 ◽  
Author(s):  
Matías Suazo ◽  
Joaquín Prieto ◽  
Andrés Escala ◽  
Dominik R. G. Schleicher
Keyword(s):  
Black Holes ◽  
Supermassive Black Holes

Inner-horizon instability and mass inflation in black holes

1989 ◽  
Vol 63 (16) ◽  
pp. 1663-1666 ◽  
Author(s):  
E. Poisson ◽  
W. Israel
Keyword(s):  
Black Holes ◽  
Inner Horizon ◽  
Mass Inflation

scholarly journals The role of Compton heating in radiation-regulated accretion on to black holes

2014 ◽  
Vol 445 (3) ◽  
pp. 2325-2330 ◽  
Author(s):  
KwangHo Park ◽  
Massimo Ricotti ◽  
Tiziana Di Matteo ◽  
Christopher S. Reynolds
Keyword(s):  
Black Holes

scholarly journals Role of electric charge in shaping equilibrium configurations of fluid tori encircling black holes

2011 ◽  
Vol 84 (8) ◽  
Author(s):  
Jiří Kovář ◽  
Petr Slaný ◽  
Zdeněk Stuchlík ◽  
Vladimír Karas ◽  
Claudio Cremaschini ◽  
...  
Keyword(s):  
Black Holes ◽  
Electric Charge ◽  
Equilibrium Configurations

scholarly journals The Role of Gravitational Instabilities in the Feeding of Supermassive Black Holes

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Giuseppe Lodato
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
High Redshift ◽  
Supermassive Black Holes ◽  
Point Of View ◽  
Accretion Discs ◽  
Theoretical Point ◽  
Interstellar Gas ◽  
Massive Black Hole

I review the recent progresses that have been obtained, especially through the use of high-resolution numerical simulations, on the dynamics of self-gravitating accretion discs. A coherent picture is emerging, where the disc dynamics is controlled by a small number of parameters that determine whether the disc is stable or unstable, whether the instability saturates in a self-regulated state or runs away into fragmentation, and whether the dynamics is local or global. I then apply these concepts to the case of AGN discs, discussing the implications of such evolution on the feeding of supermassive black holes. Nonfragmenting, self-gravitating discs appear to play a fundamental role in the process of formation of massive black hole seeds at high redshift ( 10–15) through direct gas collapse. On the other hand, the different cooling properties of the interstellar gas at low redshifts determine a radically different behaviour for the outskirts of the accretion discs feeding typical AGNs. Here the situation is much less clear from a theoretical point of view, and while several observational clues point to the important role of massive discs at a distance of roughly a parsec from their central black hole, their dynamics is still under debate.

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