Event horizon detecting invariants

Tavlayan, Aydin; Tekin, Bayram

doi:10.1103/physrevd.101.084034

“…its behavior at null spatial infinity, for locating its horizon(s) which can therefore be observed by experimental devices of finite sizes, taming its teleological nature pointed out in [43,44]. Therefore, we have explicitly shown that the horizon constitutes a local property of the manifold (in agreement with the core principles of any relativistic field theory), and that a curvature invariant can be constructed for its detection once the geometrical symmetries of the spacetime are known regardless the gravitational theory behind it: this is consistent with the geometric horizon conjecture [40,[45][46][47][48][49][50][51][52][53]. On the other hand, our results are important also from the practical point of view in light of the so-called excision technique in numerical relativity: the black hole horizon constitutes a causal boundary separating the evolutions of phenomena occurring outside it from what it may happen inside; thus, the spacetime region delimited by the horizon must be removed (or excised) when performing numerical simulations of the evolution of a black hole.…”

Section: A Curvature Syzygyssupporting

confidence: 84%

A Critical Assessment of Black Hole Solutions With a Linear Term in Their Redshift Function

Gregoris,

Ong,

Wang

2021

Preprint

0

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Different theories of gravity can admit the same black hole solution, but the parameters usually have different physical interpretations. In this work we study in depth the linear term βr in the redshift function of black holes, which arises in conformal gravity, de Rham-Gabadadze-Tolley (dRGT) massive gravity, f (R) gravity (as approximate solution) and general relativity. Geometrically we quantify the parameter β in terms of the curvature invariants. Astrophysically we found that β can be expressed in terms of the cosmological constant, the photon orbit radius and the innermost stable circular orbit (ISCO) radius. The metric degeneracy can be broken once black hole thermodynamics is taken into account. Notably, we show that under Hawking evaporation, different physical theories with the same black hole solution (at the level of the metric) can lead to black hole remnants with different values of their physical masses with direct consequences on their viability as dark matter candidates. In particular, the mass of the graviton in massive gravity can be expressed in terms of the cosmological constant and of the formation epoch of the remnant. Furthermore the upper bound of remnant mass can be estimated to be around 0.5 × 10 27 kg.

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“…its behavior at null spatial infinity, for locating its horizon(s) which can therefore be observed by experimental devices of finite sizes, taming its teleological nature pointed out in [43,44]. Therefore, we have explicitly shown that the horizon constitutes a local property of the manifold (in agreement with the core principles of any relativistic field theory), and that a curvature invariant can be constructed for its detection once the geometrical symmetries of the spacetime are known regardless the gravitational theory behind it: this is consistent with the geometric horizon conjecture [40,[45][46][47][48][49][50][51][52][53]. On the other hand, our results are important also from the practical point of view in light of the so-called excision technique in numerical relativity: the black hole horizon constitutes a causal boundary separating the evolutions of phenomena occurring outside it from what it may happen inside; thus, the spacetime region delimited by the horizon must be removed (or excised) when performing numerical simulations of the evolution of a black hole.…”

Section: Curvature Syzygyssupporting

confidence: 82%

A critical assessment of black hole solutions with a linear term in their redshift function

Gregoris

¹

,

Ong

²

,

Wang

³

2021

View full text Add to dashboard Cite

Different theories of gravity can admit the same black hole solution, but the parameters usually have different physical interpretations. In this work we study in depth the linear term $$\beta r$$ β r in the redshift function of black holes, which arises in conformal gravity, de Rham–Gabadadze–Tolley (dRGT) massive gravity, f(R) gravity (as approximate solution) and general relativity. Geometrically we quantify the parameter $$\beta $$ β in terms of the curvature invariants. Astrophysically we found that $$\beta $$ β can be expressed in terms of the cosmological constant, the photon orbit radius and the innermost stable circular orbit (ISCO) radius. The metric degeneracy can be broken once black hole thermodynamics is taken into account. Notably, we show that under Hawking evaporation, different physical theories with the same black hole solution (at the level of the metric) can lead to black hole remnants with different values of their physical masses with direct consequences on their viability as dark matter candidates. In particular, the mass of the graviton in massive gravity can be expressed in terms of the cosmological constant and of the formation epoch of the remnant. Furthermore the upper bound of remnant mass can be estimated to be around $$0.5 \times 10^{27}$$ 0.5 × 10 27 kg.

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“…In [119], a set of curvature scalars was proposed to detect the location of the event horizon and the ergosurface as well as to define some other properties, such as the mass and the spin of the black hole: [119,120]…”

Section: Thermodynamics Properties Of the Black Holementioning

confidence: 99%

Black Hole in Quantum Wave Dark Matter

Pantig

¹

,

Овгун

²

2022

Fortschritte der Physik

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In this work, we explored the effect of the fuzzy dark matter (FDM) (or wave dark matter) halo on a supermassive black hole (SMBH). Such a dark matter introduces a soliton core density profile, and we treat it ideally as a spherical distribution that surrounds the SMBH located at its center. In this direction, we obtained a new metric due to the union of the black hole and dark matter spacetime geometries. We applied the solution to the two known SMBH ‐ Sgr. A* and M87* and used the empirical data for the shadow diameter by EHT to constrain the soliton core radius rnormalc$r_\text{c}$ given some values of the boson mass mnormalb$m_\text{b}$. Then, we examine the behavior of the shadow radius based on such constraints and relative to a static observer. We found that different shadow sizes are perceived at regions robsrc$r_\text{obs}>r_\text{c}$, and the deviation is greater for values mb<10−22$m_\text{b}<10^{-22}$ eV. Concerning the shadow behavior, we have also analyzed the effect of the soliton profile on the thin‐accretion disk. Soliton dark matter effects manifest through the varying luminosity near the event horizon. We also analyzed the weak deflection angle and the produced Einstein rings due to soliton effects. We found considerable deviation, better than the shadow size deviation, for the light source near the SMBH with impact parameters comparable to the soliton core. Our results suggest the possible experimental detection of soliton dark matter effects using an SMBH at the galactic centers.

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Event horizon detecting invariants

Cited by 10 publications

References 17 publications

A Critical Assessment of Black Hole Solutions With a Linear Term in Their Redshift Function

A Critical Assessment of Black Hole Solutions With a Linear Term in Their Redshift Function

A critical assessment of black hole solutions with a linear term in their redshift function

Black Hole in Quantum Wave Dark Matter

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