Event horizon silhouette: implications to supermassive black holes in the galaxies M87 and Milky Way

Dokuchaev, V. I.; Nazarova, Natalia O.; Smirnov, Vadim P.

doi:10.1007/s10714-019-2564-8

Cited by 21 publications

(19 citation statements)

References 48 publications

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“…The size of the event horizon silhouette, computed in Ref. [17], turns out to be in the agreement with the prediction of the general relativity.…”

Section: Introductionsupporting

confidence: 70%

Spin oscillations of neutrinos scattered off a rotating black hole

Dvornikov

2020

Eur. Phys. J. C

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Spin oscillations of neutrinos, gravitationally scattered off a black hole (BH), are studied. The cases of nonrotating and rotating BHs are analyzed. We derive the analytic expressions for the transition and survival probabilities of spin oscillations when neutrinos interact with these gravitational backgrounds. The obtained transition probabilities depend on the impact parameter, as well as the neutrino energy and the particle mass. We find that there is a possibility of spin oscillations of ultrarelativistic neutrinos scattering off a rotating BH. Then, considering the neutrino scattering off BH surrounded by background matter, we derive the effective Schrödinger equation for spin oscillations. The numerical solution of this equation is obtained in the case of a supermassive BH with a realistic accretion disk. Spin effects turn out to be negligible in the neutrino scattering in the Schwarzschild metric. In the Kerr metric, we find that the observed neutrino fluxes can be reduced almost 10% because of spin oscillations when ultrarelativistic neutrinos experience gravitational scattering. The neutrino interaction with an accretion disk results in the additional modification of the intensities of outgoing neutrino fluxes. We consider the applications of the obtained results for the neutrino astronomy.

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“…The size of the event horizon silhouette, computed in Ref. [17], turns out to be in the agreement with the prediction of the general relativity.…”

Section: Introductionsupporting

confidence: 70%

Spin oscillations of neutrinos scattered off a rotating black hole

Dvornikov

2020

Eur. Phys. J. C

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“…The solid green, blue, and purple curves show A S , A J , and A Q that are derived in [21] and implicitly defined in Eqs. ( 5), (6), and (7). The cyan curves show the influence of an external quadrupolar potential from a cluster of ambient stars of mass 200 M ⊙ at a distance of 3 × 10 4 times the black hole mass M.…”

Section: Relationship Between Observations and Theoretical Modelmentioning

confidence: 99%

“…The supermassive black hole at the center of our galaxy provides unique opportunities to investigate dynamics near a strongly gravitating source [1,2]. Radio telescopes have imaged the immediate vicinity of the black hole [3,4], allowing direct constraints on the strong gravitational field regime near the black hole via imaging accretion flows [5][6][7][8][9][10]. Stellar motions also constrain the number and orbits of nearby perturbers [11].…”

Section: Introductionmentioning

confidence: 99%

Testing the black hole no-hair theorem with Galactic Center stellar orbits

O’Shaughnessy

Brady

2021

Phys. Rev. D

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Theoretical investigations have provided proof-of-principle calculations suggesting measurements of stellar or pulsar orbits near the Galactic Center could strongly constrain the properties of the Galactic Center black hole, local matter, and even the theory of gravity itself. As in previous studies, we use a Markov chain Monte Carlo to quantify what properties of the Galactic Center environment measurements can constrain. In this work, however, we also develop an analytic model (Fisher matrix) to understand what parameters are well-constrained and why. Using both tools, we conclude that existing astrometric measurements cannot constrain the spin of the Galactic Center black hole. Extrapolating to the precision and cadence of future experiments, we anticipate that the black hole spin can be measured with the known star S2. Our calculations show that we can measure the dimensionless black hole spin to a precision of ∼0.1 with weekly measurements of the orbit of S2 for 40 years using the GRAVITY telescope's best resolution at the Galactic Center, i.e., an angular resolution of 10 μarcsec and a radial velocity resolution of 500 m=s. An analytic expression is derived for the measurement uncertainty of the black hole spin using the Fisher matrix in terms of observation strategy, star's orbital parameters, and instrument resolution. From it we conclude that highly eccentric orbits can provide better constraints on the spin, and that an orbit with a higher eccentricity is more favorable even when the orbital period is longer. We also apply it to S62, S4711, and S4714 to show whether they can constrain the black hole spin sooner than S2. If in addition future measurements include the discovery of a new, tighter stellar orbit, then future data could conceivably enable tests of strong field gravity, by directly measuring the black hole quadrupole moment. Our simulations show that with a stellar orbit similar to that of S2 but at one-fifth the distance to the Galactic Center and GRAVITY's resolution limits on the Galactic Center, we can start to test the no-hair theorem with 20 years of weekly orbital measurements.

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“…The requested photon energy in the frame, comoving with the small disk element (or compact gas cloud) at θ = π/2, is [34,38] In this equation, the azimuth velocity V (ϕ) of the small disk element with orbital parameters E, L and Q = 0 relative the LNRF, falling in the equatorial plane onto a black hole, is…”

Section: Event Horizon Silhouettementioning

confidence: 99%

The Brightest Point in Accretion Disk and Black Hole Spin: Implication to the Image of Black Hole M87*

Dokuchaev

Nazarova

2019

Universe

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We propose the simple new method for extracting the value of the black hole spin from the direct high-resolution image of black hole by using a thin accretion disk model. In this model the observed dark region on the first image of the supermassive black hole in the galaxy M87, obtained by the Event Horizon Telescope, is a silhouette of the black hole event horizon. The outline of this silhouette is the equator of the event horizon sphere. The dark silhouette of the black hole event horizon is placed within the expected position of the black hole shadow, which is not revealed on the first image. We calculated numerically the relation between the observed position of the black hole silhouette and the brightest point in the thin accretion disk, depending on the black hole spin. From this relation we derive the spin of the supermassive black hole M87*, a = 0.75 ± 0.15.

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Event horizon silhouette: implications to supermassive black holes in the galaxies M87 and Milky Way

Cited by 21 publications

References 48 publications

Spin oscillations of neutrinos scattered off a rotating black hole

Spin oscillations of neutrinos scattered off a rotating black hole

Testing the black hole no-hair theorem with Galactic Center stellar orbits

The Brightest Point in Accretion Disk and Black Hole Spin: Implication to the Image of Black Hole M87*

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