Related papers: The vacuum polarization around an axionic stringy …
In this paper, we discuss the weak gravitational lensing in the context of stringy black holes. Initially, we examine the deflection angle of photon by charged stringy black hole. For this desire, we compute the Gaussian optical curvature…
Non-relativistic QCD axions or axion-like particles are among the most popular candidates for cold Dark Matter (DM) in the universe. We proposed to detect axion-like DM, using linearly polarized pulsar light as a probe. Because of…
In 4-dimensional General Relativity, black holes are described by the Kerr solution and are completely specified by their mass $M$ and by their spin angular momentum $J$. A fundamental limit for a black hole in General Relativity is the…
It turns out that repulsive effect due to rotation of a rotating black hole dominates over attraction due to mass for large $r$ in dimensions $>5$. This gives rise to a remarkable result that black hole in these higher dimensions in…
Observations of the cosmological large-scale structure provide well-established neutrino mass limits. We extend this argument to thermal relic axions. We calculate the axion thermal freeze-out temperature and thus their cosmological…
Spherically gravitational collapse towards a black hole with non-zero tangential pressure is studied. Exact solutions corresponding to different equations of state are given. We find that when taking the tangential pressure into account,…
It has been shown that the mass of the scalar field in the charged stringy black hole is never able to generate a potential well outside the event horizon to trap the superradiant modes. This is to say that the charged stringy black hole is…
It has been argued that a black hole horizon can support the long range fields of a Nielsen-Olesen string, and that one can think of such a vortex as black hole ``hair''. In this paper, we examine the properties of an Abelian Higgs vortex…
Near the black hole threshold in phase space, the black hole mass as a function of the initial data shows the "critical scaling" M \simeq C (p-p_*)^\gamma, where p labels a family of initial data, p_* is the value of p at the threshold, and…
We show that primordial black holes (PBHs) develop non-negligible spins through Hawking emission of the large number of axion-like particles generically present in string theory compactifications. This is because scalars can be emitted in…
We re-examine the problem of vacuum decay in the presence of spherically symmetric black holes. Within the semiclassical approximation, we study configurations describing a bubble of true vacuum propagating outside a black hole formed from…
In this paper, we investigate the influence of the angular momentum of a charged particle around non-extremal and extremal Einstein-Maxwell-Dilaton-Axion black holes on the Lyapunov exponent. The angular momentum's ranges and spatial…
A polarized gamma ray emission spread over a sufficiently wide energy band from a strongly magnetized astrophysical object like gamma ray bursts (GRBs) offers an opportunity to test the hypothesis of invisible axion. The axionic induced…
Zajacek et al made an interesting theoretical prediction on the electrification of a non-rotating black hole; if a non-rotating black hole is surrounded by plasma composed of protons and electrons, it will acquire electric charge due to the…
Most black holes are known to be unstable to emitting Hawking radiation (in asymptotically flat spacetime). If the black holes are non-extreme, they have positive temperature and emit thermally. If they are extremal rotating black holes,…
We consider the spacetimes corresponding to static Global Monopoles with interior boundaries corresponding to a Black Hole Horizon and analyze the behavior of the appropriate ADM mass as a function of the horizon radius r_H. We find that…
We propose a novel experiment to search for axion dark matter which differentiates the phase velocities of the left and right-handed polarized photons. Our optical cavity measures the difference of the resonant frequencies between two…
Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm. In the present paper we consider four benchmark measurements: the universality of the central surface density of galaxy…
In this paper we generalize the black hole bound of arXiv:0706.2050 to de Sitter spaces, and apply it to various vacua in the landscape, with a special emphasis on slow-roll inflationary vacua. Non-trivial constraints on the lifetime and…
Massive stellar gravitational collapse is not an endless process. The Standard Model of particle physics predicts the existence of a repulsive interaction, two-neutrino mediated, with a coherent weak charge of macroscopic matter…