1,720,984 research outputs found
Traces of quantum gravitational correction at third-order curvature through the black hole shadow and particle deflection at the weak field limit
Full text linkThis study investigates the impact of the quantum-gravity correction at the third-order curvature () on the black hole\u27s shadow and deflection angle on the weak field regime, both involving finite distances of observers. While the calculation of the photonsphere and shadow radius can easily be achieved by the standard Lagrangian for photons, the deflection angle employs the finite-distance version of the Gauss-Bonnet theorem (GBT). We find that the photonsphere reduces to the classical expression for both the Planck mass and the theoretical mass limit for BH, thus concealing the information about the applicability of the metric on the quantum and astrophysical grounds. Our calculation of the shadow, however, revealed that is strictly negative and constrains the applicability of the metric to quantum black holes. For instance, the bounds for the mass is . We also derived the analytic formula for the observer-dependent shadow, which confirms \u27s influence on quantum black holes even for observers in the asymptotic regions. The influence of such a parameter also strengthens near the quantum black hole. Our analytic calculation of is shown to be independent of if the finite distance , and is not coupled to any time-like geodesic. Finally, the effect of manifests in two ways: if is large enough to offset the small value of (which is beyond the theoretical mass limit), or if is comparable to for a quantum black hole.9 pages, 0 figures. Comments are welcome
Probing Schwarzschild-like Black Holes in Metric-Affine Bumblebee Gravity with Accretion Disk, Deflection Angle, Greybody Bounds, and Neutrino Propagation
Full text linkIn this paper, we investigate Schwarzschild-like black holes within the
framework of metric-affine bumblebee gravity. We explore the implications of
such a gravitational setup on various astrophysical phenomena, including the
presence of an accretion disk, the deflection angle of light rays, the
establishment of greybody bounds, and the propagation of neutrinos. The
metric-affine bumblebee gravity theory offers a unique perspective on
gravitational interactions by introducing a vector field that couples to
spacetime curvature. We analyze the behavior of accretion disks around
Schwarzschild-like black holes in this modified gravity scenario, considering
the effects of the bumblebee field on the accretion process. Furthermore, we
scrutinize the deflection angle of light rays as they traverse the
gravitational field, highlighting potential deviations from standard
predictions due to the underlying metric-affine structure. Investigating
greybody bounds in this context sheds light on the thermal radiation emitted by
black holes and how the modified gravity framework influences this phenomenon.
Moreover, we explore neutrino propagation around Schwarzschild-like black holes
within metric-affine bumblebee gravity, examining alterations in neutrino
trajectories and interactions compared to conventional general relativity. By
comprehensively probing these aspects, we aim to unravel the distinctive
features and consequences of Schwarzschild-like black holes in the context of
metric-affine bumblebee gravity, offering new insights into the nature of
gravitational interactions and their observable signatures.Comment: 14 pages, 7 figure
Investigating the Connection between Generalized Uncertainty Principle and Asymptotically Safe Gravity in Black Hole Signatures through Shadow and Quasinormal Modes
Full text linkThe links between the deformation parameter of the generalized
uncertainty principle (GUP) to the two free parameters and
of the running Newtonian coupling constant of the Asymptotic Safe
gravity (ASG) program, has been conducted recently in [Phys.Rev.D 105 (2022)
12, 124054]. In this paper, we test these findings by calculating and examining
the shadow and quasinormal modes of black holes and demonstrate that the
approach provides a theoretical framework for exploring the interplay between
quantum gravity and GUP. Our results confirm the consistency of ASG and GUP and
offer new insights into the nature of black holes and their signatures. The
implications of these findings for future studies in quantum gravity are also
discussed.Comment: 19 pages, 8 figure
Weak field deflection angle and analytical parameter estimation of the Lorentz-violating Bumblebee parameter through the black hole shadow using EHT data
No full textWe explored how the Lorentz symmetry breaking parameter ℓ affects the Reissner-Nordstöm BH solution in the context of weak field deflection angle, and the black hole shadow. We aim to derive the general expression for the weak deflection angle using the non-asymptotic version of the Gauss-Bonnet theorem, and we presented a way to simplify the calculations under the assumption that the distance of the source and the receiver are the same. Through the Solar System test, ℓ is constrained from around orders of magnitude to 0, implying challenging detection of ℓ through the deflection of light rays from the Sun. We also studied the black hole shadow in an analytic way, where we applied the EHT results under the far approximation in obtaining an estimate expression for ℓ. Using the realistic values of the black hole mass and observer distance for Sgr. A* and M87*, it was shown that is satisfied, implying the relevance and potential promise of the spontaneous Lorentz symmetry breaking parameter's role on the shadow radius uncertainties as measured by the EHT. We find constraints for ℓ to be negatively valued, where the upper and lower bounds are ∼ - 1.94 and ∼ - 2.04, respectively
Shadow, lensing, quasinormal modes, greybody bounds and neutrino propagation by dyonic ModMax black holes
No full textMotivated by recent work on the Modified Maxwell (ModMax) black holes [Phys Lett B 10.1016/j.physletb.2020.136011], which are invariant in duality rotations and conformal transformations founded in [Phys Rev D 10.1103/PhysRevD.102.121703], we probe its effects on the shadow cast, weak field gravitational lensing, and neutrino propagation in its vicinity. Using the EHT data for the shadow diameter of Sgr. A* and M87*, and LIGO/VIRGO experiments for the dyonic ModMax black hole perturbations, we find constraints for ModMax parameters such as and the screening factor . We also analyze how the shadow radius behaves as perceived by a static observer and one that is comoving with the cosmic expansion. The effect of the ModMax parameters is constant for a static observer, and we found That it varies when the observer is comoving with cosmic expansion. We also analyzed its effect on the weak deflection angle by exploiting the Gauss–Bonnet theorem and its application to Einstein ring formation. We also consider the finite distance effect and massive particle deflection. Our results indicate that the far approximation of massive particle gives the largest deflection angle and amplifies the effect of and . Then we also calculate the quasinormal modes and greybody bounds which encode unique characteristic features of the dyonic ModMax black hole. With the advent of improving space technology, we reported that it is possible to detect the deviation caused through the shadow cast, Einstein rings, quasinormal modes, and neutrino oscillations
The effect of dark matter on schwarzschild and kerr black holes: Considerations on the weak deflection angles and the kerr shadow
No full textWe consider the effect of a spherical dark matter distribution that surrounds a black hole of mass m. The dark matter is only characterized by its mass M, inner radius rs , and thickness ∆rs . A black hole surrounded by an astrophysical environment such as dark matter is called a dirty black hole. Considering first the dirty Schwarzschild black hole, we calculated the weak deflection angle using the [Ishihara et al., 2016] method, which considers the finite distance of the source and the receiver from the black hole. We found out the for notable deviation on the weak deflection to occur, the dark matter thickness is estimated to be ∆rs ∼ 2 √ 3mM. This implies that the weak deflection angle of a Schwarzschild black hole cannot be used to detect dark matter inside one’s galaxy unless the dark matter is distributed near it for a given value of M. Further in this study is the use of the Newman-Janis algorithm to extend the dirty Schwarzschild black hole to rotating dirty Kerr black hole. Findings indicate that considerable deviations in the horizons, null orbits, shadow radius, and its corresponding observables require high dark matter density. We also find that time-like orbits are very sensitive to deviation even if the dark matter mass to thickness ratio is estimated to be less than 10 percent. Moreover, the location where the Penrose process occurs remains uninfluenced by dark matter. The deviation in the energy emission rate indicates that dark matter tends to reduce the lifetime of a black hole. Finally, the analytic estimate for ∆rs in dirty Kerr black hole is obtained using the deviation in the weak deflection angle. Findings reveal that ∆rs for the slow-spin limit is greater than the ultra-relativistic limit. It implies that the rotation of black hole does not improve the value of ∆rs . In either case, however, these conditions are still not satisfied within our galaxy.
Index Terms—Dirty black hole; Dark matter; Gauss-Bonnet theorem; Weak deflection angle; Finite-distance; Newman-Janis algorithm; Black hole shadow; Hamilton-Jacobi formalism
Kerr black hole surrounded by dark matter: Horizon, photonosphere and shadow
No full textWe study the effect of a simple spherical model of dark matter with mass D and thickness Δr to a Kerr black hole of mass M. It is shown that the horizon and ergosphere radii are affected. We utilize the Hamilton-Jacobi equation in deriving the equations of motion to study the photonsphere and generate a black hole shadow image. For increasing D and fixed Δr, the radial distance of the photon\u27s last unstable prograde orbit tends to increase as the Kerr black hole approaches extremality. The condition also makes the photon\u27s last unstable retrograde orbit to decrease in distance from the black hole. These results to the black hole\u27s shadow radius to increase. Dramatic distortion to black hole shadow can occur if the dark matter density is abnormally high. A very low dark matter density results to an almost negligible effect to the black hole shadow. The expression for the condition such that the noticeable effect of dark matter starts to occur is rather cumbersome. A study of this kind can pave a way for sophisticated future observations to indirectly detect dark matter, if there is any
Apparent and emergent dark matter around a Schwarzschild black hole
Full text linkInspired by the two different dark matter frameworks that were studied
recently: one that arises from the non-local effects of entanglement entropy as
emergent gravity (characterized by the parameter , and zero-point scale
length ), and one from dark energy viewed as a superconducting medium
(characterized by , and screening length parameter ),
two black hole solutions spherically surrounded with these dark matter models
were derived. The effect of these two frameworks on SMBH was analyzed through
the resulting deviations in the null regions and the black hole shadow. In
addition, constraints to the parameters and (at level)
were found using the available EHT data for Sgr. A* and M87*. These constraints
allow one to deduce the effective mass , which causes uncertainties in the
measurement. On the other hand, if the effective mass is known, one can also
deduce the constants associated with , and . The former framework
also introduces an Appell function, a hypergeometric function of two variables
that separately allows the analysis of macroscopic and (hypothetical)
microscopic black holes. This first framework was found to decrease the radii
of the null regions respective to the Schwarzschild counterpart. The shadow
radius, however, behaves reversibly. The result of the numerical analysis for
the latter framework revealed increased values for the photonsphere and shadow
radii. Remarkably, the study also showed that for SMBHs, the amplifying effects
of are stronger than the scale length . Finally, results
of constraints, as an example, for the upper bound in for M87* indicated
that the effective mass causing the deviation was around given that the observed Milgrom's constant is .Comment: 12 pages, 12 figures, 1 table. Accepted for publication at PD
Constraining a one-dimensional wave-type gravitational wave parameter through the shadow of M87* via Event Horizon Telescope
Full text linkDuring the glorious success of the EHT in providing the first image of a
black hole, numerous papers have been published about the effect of different
astrophysical environments on black hole geometry. Motivated by the work on how
gravitational wave affects the shadow of a Schwarzschild black hole [Eur. Phys.
J. C 10.1140/epjc/s10052-021-09287-2], we extend it by considering a quantum
correction on the black hole through the extended uncertainty principle (EUP).
Along with this correction, we probe the gravitational wave's effect on the
null geodesics, and photonsphere, and find constraints to the gravitational
wave parameter using the black hole shadow of M87* for some given
test value for the gravitational wave frequency . Not only that some
nodes were found in the light trajectory, but the general behavior of paths
changes in a periodic way as the time progresses. These patterns then
confirm the chaotic formation of the shadow seen by some remote observer.
Finally, the constraint that we find for is orders of
magnitude for the effect of the gravitational wave to be seen at a distance of
Mpc. As a consequence of such a value for , another result
reveals that while there is are gravitational wave effect on the shadow
perceived at , the deviations on the photonsphere are nearly non-existent.
Apart from Earth-based detectors for gravitational waves, the study implies the
possibility of an alternative detection method especially if a gravitational
wave source is near a lone black hole.Comment: 10 pages, 6 figure
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