Shadows as a tool to evaluate black hole parameters and a dimension of spacetime

Zakharov, A. F.; Paolis, F. De; Ingrosso, G.; Nucita, A. A.

doi:10.1016/j.newar.2011.09.002

Cited by 56 publications

(33 citation statements)

References 85 publications

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“…Assuming that a radiation in a spectral line is emitted from a disk near a black hole horizon, it was found (and after that it was observed the X-ray K α -line) that an observed shape of the spectral line can be an important indicator of a strong gravitational field near a black hole, moreover, one can evaluate a black hole spin analyzing a spectral line structure [78][79][80] 2 (see also more recent reviews [88,89] on the subject). Another phenomenon, where one really needs a strong gravitational field approach, is simulations of a shadow formation started since [90][91][92][93] (see also calculations of shadows for different cases [94][95][96][97][98][99] and recent reviews on the subject [100,101]). …”

Section: Observational Signatures Of Black Holesmentioning

confidence: 99%

Graviton mass bounds from an analysis of bright star trajectories at the Galactic Center

2017

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Abstract. In February 2016 the LIGO & VIRGO collaboration reported the discovery of gravitational waves in merging black holes, therefore, the team confirmed GR predictions about an existence of black holes and gravitational waves in the strong gravitational field limit. Moreover, in their papers the joint LIGO & VIRGO team presented an upper limit on graviton mass such as m g < 1.2 × 10 −22 eV . So, the authors concluded that their observational data do not show any violation of classical general relativity. We show that an analysis of bright star trajectories could constrain graviton mass with a comparable accuracy with accuracies reached with gravitational wave interferometers and the estimate is consistent with the one obtained by the LIGO & VIRGO collaboration. This analysis gives an opportunity to treat observations of bright stars near the Galactic Center as a useful tool to obtain constraints on the fundamental gravity law such as modifications of the Newton gravity law in a weak field approximation. In that way, based on a potential reconstruction at the Galactic Center we obtain bounds on a graviton mass.

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Section: Observational Signatures Of Black Holesmentioning

confidence: 99%

Graviton mass bounds from an analysis of bright star trajectories at the Galactic Center

2017

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“…spectral line structure [1,2,3] 8 (see also more recent reviews [11,12] on the subject). Another phenomenon, where one really needs a strong gravitational field approach, is simulations of a shadow formation started since [13,14,15,16] (see also calculations of shadows for different cases [17,18,19,20,21,22] and recent reviews on the subject [23,24]). The problem is connected with attempts to resolve the smallest spot at the Galactic Center with VLBI interferometry in mm-band [25].…”

Section: Introductionmentioning

confidence: 99%

Graviton mass evaluation with trajectories of bright stars at the Galactic Center

Jovanović

Borka

Jovanović

2017

J. Phys.: Conf. Ser.

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“…In such situations, the ratio of the triples of the resonant frequencies is directly related to the black hole spin, independently of the black hole mass. The related possibility of directly measuring the black hole spin is very important because of relatively high uncertainties in observational estimates of the black hole mass that are necessary for determining the black hole spin in general resonant phenomena (Török et al , 2011, or in black hole spin determinations based on the measurements of profiled spectral lines (Laor 1991;Karas et al 1992;Dovčiak et al 2004;Fabian & Miniutti 2005;Zakharov 2003;Zakharov & Repin 2006;Zakharov et al 2012;Fanton et al 1997;Čadež et al 2003;Čadež & Calvani 2005).…”

Section: Discussionmentioning

confidence: 99%

Multi-resonance orbital model of high-frequency quasi-periodic oscillations: possible high-precision determination of black hole and neutron star spin

Stuchlík

Kotrlová

Török

2013

A&A

107

129

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Context. Using known frequencies of the twin-peak high-frequency quasiperiodic oscillations (HF QPOs) and known mass of the central black hole, the black-hole dimensionless spin a can be determined by assuming a concrete version of the resonance model. However, a wide range of observationally limited values of the black hole mass implies low precision of the spin estimates. Aims. We discuss the possibility of higher precision for the black hole spin a measurements in the framework of a multi-resonance model inspired by observations of more than two HF QPOs in the black hole systems, which are expected to occur at two (or more) different radii of the accretion disc. This framework is also applied in a modified form to the neutron star systems. Methods. We determine the spin and mass dependence of the twin-peak frequencies with a general rational ratio n:m, assuming a non-linear resonance of oscillations with the epicyclic and Keplerian frequencies or their combinations. In the multi-resonant model, the twin-peak resonances are combined properly to give the observed frequency set. For the black hole systems we focus on the special case of duplex frequencies, when the top, bottom, or mixed frequency is common at two different radii where the resonances occur giving triple frequency sets. Results. The sets of triple frequency ratios and the related spin a are given. The resonances are considered up to n = 5 since excitation of higher order resonances is improbable. The strong resonance model for "magic" values of the black hole spin means that two (or more) versions of resonance could occur at the same radius, allowing cooperative effects between the resonances. For neutron star systems we introduce a resonant switch model that assumes switching of oscillatory modes at resonant points. Conclusions. In the case of doubled twin-peak HF QPOs excited at two different radii with common top, bottom, or mixed frequency, the black hole spin a is given by the triple frequency ratio set. The spin is determined precisely, but not uniquely, because the same frequency set could correspond to more than one concrete spin a. The black hole mass is given by the magnitude of the observed frequencies. The resonant switch model puts relevant limits on the mass and spin of neutron stars, and we expect a strong increase in the fitting procedure precision when different twin oscillatory modes are applied to data in the vicinity of different resonant points. We expect the multi-resonance model to be applicable to data from the planned LOFT or similar X-ray satellite observatory.

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Shadows as a tool to evaluate black hole parameters and a dimension of spacetime

Cited by 56 publications

References 85 publications

Graviton mass bounds from an analysis of bright star trajectories at the Galactic Center

Graviton mass bounds from an analysis of bright star trajectories at the Galactic Center

Graviton mass evaluation with trajectories of bright stars at the Galactic Center

Multi-resonance orbital model of high-frequency quasi-periodic oscillations: possible high-precision determination of black hole and neutron star spin

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