Related papers: The dynamics of S-stars and G-sources orbiting a s…

We investigate the structural and oscillation properties of dark matter (DM) admixed strange quark stars (DMSQSs). The strange quark matter (SQM) is described with the well-known Nambu-Jona-Lasino (NJL) model and the self-interacting…

We implement a Markov Chain Monte Carlo method to obtain posterior probability distributions for the parameters of the S2 star orbit around Sagittarius A*, for seven representative non-rotating black hole space-time solutions. In…

The structure of dark matter admixed neutron stars (DANSs) are investigated, adopting a non-annihilating self-interacting fermionic dark matter (DM) model, with a particular focus on the case of the light DM particle mass $m_D \in…

One of the most compelling candidates for Dark Matter (DM) are light pseudo-scalar particles (axions), motivated by the strong CP problem and axiverse scenario in string theory. Depending on their mass and type of self-interaction, these…

In the Milky Way the central massive black hole, SgrA*, coexists with a compact nuclear star cluster that contains a sub-parsec concentration of fast-moving young stars called S-stars. Their location and age are not easily explained by…

Till today, the nature of Dark Matter (DM) remains elusive despite all our efforts. This missing matter of the universe has not been observed by the already operating DM direct-detection experiments, but we can infer its gravitational…

We investigate the connection between supermassive black holes (SMBHs) and their host dark matter halos in the local universe using the clustering statistics and luminosity function of AGN from the Swift/BAT AGN Spectroscopic survey (BASS…

Our Galactic Center, Sagittarius A* (Sgr A*), is believed to harbour a supermassive black hole (BH), as suggested by observations tracking individual orbiting stars. Upcoming sub-millimetre very-long-baseline-interferometry (VLBI) images of…

The hierarchical nature of galaxy formation suggests that a supermassive black hole binary could exist in our galactic center. We propose a new approach to constraining the possible orbital configuration of such a binary companion to the…

A preliminary estimation of gravitational waves (GWs) from the extreme-mass-ratio-inspirals (EMRIs) system in the Galactic Centre (GC) is given for the 37 observed S-stars revolving around the supermassive black hole (SMBH) at Sagittarius…

Recent observations of the Milky-way galactic center at various frequencies suggest a supermassive compact object. Generally, that supermassive compact object is assumed to be a `Black Hole', having more than four million solar masses. In…

In this work I use astrometric and spectroscopic data on the S2 star at the Galactic Centre (GC) up to 2016 to derive specific constraints on the size of a dark matter (DM) spike around the central supermassive black hole Sgr A*. These…

Merging compact black-hole (BH) binaries are likely to exist in the nuclear star clusters around supermassive BHs (SMBHs), such as Sgr A$^\ast$. They may also form in the accretion disks of active galactic nuclei. Such compact binaries can…

We study an impact of asymmetric fermionic dark matter on neutron star properties, including tidal deformability, mass, radius, etc. We present the conditions at which dark matter particles tend to form a compact structure in a core of the…

Two recent papers (Ghez et al. 2008, Gillessen et al. 2009) have estimated the mass of and the distance to the massive black hole in the center of the Milky Way using stellar orbits. The two astrometric data sets are independent and yielded…

A dynamically relaxed dense cluster comprised of about 40 stars (the so-called S-stars) inhabits the central region of the Galaxy. Their stars revolve around the Sgr A$^*$ massive object. To understand the dynamical evolution of planetary…

The Galactic center provides a unique astrophysical laboratory for us to study various astrophysical processes. In this paper, we review and outline the latest results from observations of Sgr~A$^*$ in terms of source structure and…

In this paper, we start from a static black hole (BH) immersed in a Deanne-type dark matter (DM) halo and employ the Newman-Janis algorithm (NJA) to generate the rotating black hole solution with a dark matter halo. Also, we have checked…

Studying the orbital motion of stars around Sagittarius A* in the Galactic Center provides a unique opportunity to probe the gravitational potential near the supermassive black hole at the heart of our Galaxy. Interferometric data obtained…

This thesis includes two main projects. In the first part, we assess the feasibility of a recently suggested strong-field general relativity test, in which future observations of a hypothetical class of stars orbiting very close to the…