A parametrization to test black hole candidates with the spectrum of thin disks

Lin, Nan; Tsukamoto, Naoki; Ghasemi-Nodehi, M.; Bambi, Cosimo

doi:10.1140/epjc/s10052-015-3837-3

Cited by 31 publications

(55 citation statements)

References 75 publications

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“…This constrains a combination of the modification to the angular momentum of a test-particle in a non-Kerr spacetime and a modification to the location of the ISCO. The constraint above can be refined further by specifying a parametrically deformed Kerr spacetime [104,146,[246][247][248][249][250][251][252][253][254][255][256]. To give a concrete example, let us consider the quasi-Kerr metric [104], which is constructed to represent a generic deformation to the Kerr metric through a correction in its quadrupole moment…”

Section: Theoretical Implications For Exotic Spacetimesmentioning

confidence: 99%

Theoretical physics implications of the binary black-hole mergers GW150914 and GW151226

2016

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The gravitational wave observations GW150914 and GW151226 by Advanced LIGO provide the first opportunity to learn about physics in the extreme gravity environment of coalescing binary black holes. The LIGO Scientific Collaboration and the Virgo Collaboration have verified that this observation is consistent with Einstein's theory of General Relativity, constraining the presence of certain parametric anomalies in the signal. This paper expands their analysis to a larger class of anomalies, highlighting the inferences that can be drawn on non-standard theoretical physics mechanisms that could otherwise have affected the observed signals. We find that these gravitational wave events constrain a plethora of mechanisms associated with the generation and propagation of gravitational waves, including the activation of scalar fields, gravitational leakage into large extra dimensions, the variability of Newton's constant, the speed of gravity, a modified dispersion relation, gravitational Lorentz violation and the strong equivalence principle. Though other observations limit many of these mechanisms already, GW150914 and GW151226 are unique in that they are direct probes of dynamical strong-field gravity and of gravitational wave propagation. We also show that GW150914 constrains inferred properties of exotic compact object alternatives to Kerr black holes. We argue, however, that the true potential for GW150914 to both rule out exotic objects and constrain physics beyond General Relativity is severely limited by the lack of understanding of the coalescence regime in almost all relevant modified gravity theories. This event thus significantly raises the bar that these theories have to pass, both in terms of having a sound theoretical underpinning, and reaching the minimal level of being able to solve the equations of motion for binary merger events. We conclude with a discussion of the additional inferences that can be drawn if the lower-confidence observation of an electromagnetic counterpart to GW150914 holds true, or such a coincidence is observed with future events; this would provide dramatic constraints on the speed of gravity and gravitational Lorentz violation.

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Section: Theoretical Implications For Exotic Spacetimesmentioning

confidence: 99%

Theoretical physics implications of the binary black-hole mergers GW150914 and GW151226

2016

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“…The latter can confirm the Kerr nature of black hole candidates by constraining the values of the deformation parameters. There are several proposals in the literature, each of these with its advantages and disadvantages [13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…In the metrics proposed in [13][14][15][16][17][18][19], the Kerr solution is recovered when all the deformation parameters vanish. The defor-mation parameters introduce thus some additional terms, which should describe the spacetime geometry around black holes in alternative theories of gravity.…”

Section: Introductionmentioning

confidence: 99%

Note on a new parametrization for testing the Kerr metric

Ghasemi-Nodehi

Bambi

2016

Eur. Phys. J. C

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We propose a new parametrization for testing the Kerr nature of astrophysical black hole candidates. The common approaches focus on the attempt to constrain possible deviations from the Kerr solution described by new terms in the metric. Here we adopt a different perspective. The mass and the spin of a black hole make the spacetime curved and we want to check whether they do it with the strength predicted by general relativity. As an example, we apply our parametrization to the black hole shadow, an observation that may be possible in a not too distant future.

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“…Accretion around wormholes has also been an active area of research [32,33], more so because wormholes are special types of objects sourced by materials that violate at least the Null Energy Condition (hence exotic). Research included also other types of objects, e.g., quark, boson and fermion stars, brane-world black holes, gravastars, naked singularities (NS) [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50], f (R)-modified gravity models of black holes [51][52][53] and so on. One of the most promising method to distinguish different types of astrophysical objects through their accretion disk properties is the profile analysis of K α iron line [54][55][56][57][58].…”

Section: Introductionmentioning

confidence: 99%

Accretion disk around the rotating Damour–Solodukhin wormhole

Karimov¹,

Izmailov²,

Nandi³

2019

Eur. Phys. J. C

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A new rotating generalization of the Damour-Solodukhin wormhole (RDSWH), called Kerr-like wormhole, has recently been proposed and investigated by Bueno et al. for echoes in the gravitational wave signal. We show a novel feature of the RDSWH, viz., that the kinematic properties such as the ISCO or marginally stable radius r ms , efficiency and the disk potential V eff are independent of λ (which means they are identical to their KBH counterparts for any given spin). Differences however appear in the emissivity properties for higher values 0.1 < λ ≤ 1 (say) and for the extreme spin a = 0.998. The kinematic and emissivity are generic properties as variations of the wormhole mass and the rate of accretion within the model preserve these properties. Specifically, the behavior of the luminosity peak is quite opposite to each other for the two objects, which could be useful from the viewpoint of observations. Apart from this, an estimate of the difference Δ λ in the maxima of flux of radiation F(r) shows non-zero values but is too tiny to be observable at present for λ < 10 −3 permitted by the strong lensing bound. The broad conclusion is that RDSWH are experimentally indistinguishable from KBH by accretion characteristics.

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A parametrization to test black hole candidates with the spectrum of thin disks

Cited by 31 publications

References 75 publications

Theoretical physics implications of the binary black-hole mergers GW150914 and GW151226

Theoretical physics implications of the binary black-hole mergers GW150914 and GW151226

Note on a new parametrization for testing the Kerr metric

Accretion disk around the rotating Damour–Solodukhin wormhole

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