Imprints of dark matter on black hole shadows using spherical accretions

Abstract

We study the possibility of identifying dark matter in the galactic center from the physical properties of the electromagnetic radiation emitted from an optically-thin disk region around a static and spherically symmetric black hole. In particular, we consider two specific models for the optical-thin disk region: a gas at rest and a gas in a radial free fall. Due to the effect of dark matter on the spacetime geometry, we find that the dark matter can increase or decrease the intensity of the electromagnetic flux radiation depending on the dark matter model. To this end, we analyze two simple dark matter models having different mass functions $${\mathcal {M}}(r)$$ M ( r ) , with a matter mass M, thickness $$\Delta r_s$$ Δ r s along with a dark matter core radius surrounding the black hole. In addition to that, we explore the scenario of a perfect fluid dark matter surrounding the black hole. We show that in order to have significant effect of dark matter on the intensity of the electromagnetic flux radiation, a high energy density of dark matter near the black hole is needed. We also find that the surrounding dark matter distribution plays a key role on the shadow radius and the intensity of the electromagnetic flux radiation, respectively. Finally we have used the relation between the shadow radius and the quasinormal modes (QNMs) to compute the real part of QNM frequencies.

Constraints on Barrow Entropy from M87* and S2 Star Observations

“…Via this simple model, we can extract valuable information about the intensity of the radiation which can be detected by a distant observer. In order to achieve this we need to estimate the specific intensity at the observed photon frequency ν obs at the point (X, Y) of the observer's image [37,47,[89][90][91][92].…”

“…It is important to mention here that sign +(−) describes the case when the photon approaches (or draws away) from the black hole. The redshift function g can be calculated using [37,47,[89][90][91][92].…”

Image of a regular phantom compact object and its luminosity under spherical accretions

“…The effects of spherical accretion on the shadow for a four-dimensional Gauss-Bonnet black hole has been studied in [29], which indicates that the Gauss-Bonnet constant enhances the observed specific intensity of the black hole image. For a black hole with by dark matter hair [30], the intensity of the electromagnetic flux radiation in the spherical accretion depends on the dark matter model, and the dark matter distribution plays an important role on the shadow radius and the intensity of the electromagnetic flux radiation. Moreover, the effects of quintessence dark energy on image of black hole on the intensity of flux radiation is also investigated in the spherical accretion [31].…”

Joule-Thomson Expansion of RN-AdS Black Hole Immersed in Perfect Fluid Dark Matter

“…Based on this idea, the charged AdS black hole thermodynamic properties and plenty of other studies were successfully investigated [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24].…”