New parametrization for spherically symmetric black holes in metric theories of gravity

Rezzolla, Luciano; Zhidenko, A.

doi:10.1103/physrevd.90.084009

Cited by 207 publications

(247 citation statements)

References 67 publications

(127 reference statements)

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“…Spacetime is axisymmetric, not spherically symmetric, and if we try to alter by hand the Kerr metric it is difficult to avoid creating a spacetime with pathological features like naked singularities and regions with closed time-like curves. For the time being, there is not yet a standard formalism for testing the Kerr metric, even if some proposals are present in the literature (Johannsen & Psaltis 2011;Cardoso et al 2014;Rezzolla & Zhidenko 2014). In what follows, we adopt the Cardoso-Pani-Rico parametrization (Cardoso et al 2014 { }  (at increasingly high order).…”

Section: Testing the Kerr Paradigmmentioning

confidence: 99%

Testing the Kerr Nature of Black Hole Candidates Using Iron Line Spectra in the CPR Framework

Jiang

Bambi

Steiner

2015

ApJ

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The iron Kα line commonly observed in the X-ray spectrum of both stellar-mass and supermassive black hole (BH) candidates originates from X-ray fluorescence of the inner accretion disk. Accordingly, it can be used to map the spacetime geometry around these objects. In this paper, we extend previous work using the iron Kα line to test the Kerr BH hypothesis. We adopt the Cardoso-Pani-Rico parametrization and we test the possibility of constraining possible deviations from the Kerr solution that can be obtained from observations across the range of BH spins and inclination angles. We confirm previous claims that the iron Kα line is potentially a quite powerful probe for testing the Kerr metric given sufficiently high quality data and with systematics under control, especially in the case of fast-rotating BHs and high inclination angles since both conditions serve to maximize relativistic effects. We find that some geometric perturbations from Kerr geometry manifest more strongly in the iron line profile than others. While the perturbation parameter t 3  can be well constrained by the iron line profile, an orthogonal data set is necessary to constrain departures from Kerr geometry in .

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Section: Testing the Kerr Paradigmmentioning

confidence: 99%

Testing the Kerr Nature of Black Hole Candidates Using Iron Line Spectra in the CPR Framework

Jiang

Bambi

Steiner

2015

ApJ

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“…[8][9][10]), and investigate how much observations can constrain such deformations. A second avenue corresponds to attempts of studying generic black-hole spacetimes under some sufficiently broad parametrization scheme, with Schwarzschild and Kerr being particular realizations of the general framework, rather than fiducial solutions [11,12]. These two first approaches may be informative, but have the unsatisfactory feature that the deformed geometries, in general, do not have a clear origin as solutions of any sensible model.…”

Section: Introductionmentioning

confidence: 99%

Astrophysical imaging of Kerr black holes with scalar hair

et al. 2016

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We address the astrophysical imaging of a family of deformed Kerr black holes (BHs). These are stationary, asymptotically flat BH spacetimes that are solutions of general relativity minimally coupled to a massive, complex scalar field: Kerr BHs with scalar hair (KBHsSH). Such BHs bifurcate from the vacuum Kerr solution and can be regarded as a horizon within a rotating boson star. In a recent letter [P. V. P. Cunha, C. A. R. Herdeiro, E. Radu, and H. F. Rúnarsson, Phys. Rev. Lett. 115, 211102 (2015).], it was shown that KBHsSH can exhibit very distinct shadows from the ones of their vacuum counterparts. The setup therein, however, considers the light source to be a celestial sphere sufficiently far away from the BH. Here, we analyze KBHsSH surrounded by an emitting torus of matter simulating a more realistic astrophysical environment, and study the corresponding lensing of light as seen by a very faraway observer, to appropriately model ground-based observations of Sgr A Ã . We find that the differences in imaging between KBHsSH and comparable vacuum Kerr BHs remain, albeit less dramatic than those observed for the corresponding shadows in the previous setup. In particular, we highlight two observables that might allow differentiating KBHsSH and Kerr BHs. The first is the angular size of the photon ring (in a Kerr spacetime) or lensing ring (in a KBHSH spacetime), the latter being significantly smaller for sufficiently non-Kerr-like spacetimes. The second is the existence of an edge in the intensity distribution (the photon ring in Kerr spacetime). This edge can disappear for very non-Kerr-like KBHsSH. It is plausible, therefore, that sufficiently precise very long baseline interferometric observations of BH candidates can constrain this model.

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“…This implies that, at least for the Johannsen and Psaltis's model, the last circular orbit might be larger than the ISCO, because the ISCO (in the usual sense) often refers to the smallest circular orbit that is stable against the radial perturbation. [3,5,11,12,[22][23][24]26] It is left as a future work to study a more general case.…”

Section: Discussionmentioning

confidence: 99%

Nonradial stability of marginal stable circular orbits in stationary axisymmetric spacetimes

Ono¹,

Suzuki²,

Asada³

2016

Phys. Rev. D

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We study linear nonradial perturbations and stability of a marginal stable circular orbit (MSCO) such as the innermost stable circular orbit (ISCO) of a test particle in stationary axisymmetric spacetimes which possess a reflection symmetry with respect to the equatorial plane. A zenithal stability criterion is obtained in terms of the metric components, the specific energy and angular momentum of a test particle. The proposed approach is applied to Kerr solution and MajumdarPapapetrou solution to Einstein equation. Moreover, we reexamine MSCOs for a modified metric of a rapidly spinning black hole that has been recently proposed by Johannsen and Psaltis [PRD, 83, 124015 (2011)]. We show that, for the Johannsen and Psaltis's model, circular orbits that are stable against radial perturbations for some parameter region become unstable against zenithal perturbations. This suggests that the last circular orbit for this model may be larger than the ISCO.

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New parametrization for spherically symmetric black holes in metric theories of gravity

Cited by 207 publications

References 67 publications

Testing the Kerr Nature of Black Hole Candidates Using Iron Line Spectra in the CPR Framework

Testing the Kerr Nature of Black Hole Candidates Using Iron Line Spectra in the CPR Framework

Astrophysical imaging of Kerr black holes with scalar hair

Nonradial stability of marginal stable circular orbits in stationary axisymmetric spacetimes

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