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

Fermionic dark matter (DM) with attractive self-interaction is possible to form black holes (BH) inside the Gyr-old neutron stars (NS). Therefore by observing such NS corresponding to their adjacent DM environments can place bounds on DM…

Sagittarius A* (Sgr A*) is the central supermassive black hole with the mass $\sim 4\times 10^6 M_{\odot}$ in the Milky Way and stars are orbiting around it. In May 2018, one of the nearest stars to Sgr A* named S0-2/S2 experienced the…

We construct a charged Bardeen black hole (BH) surrounded by perfect fluid dark matter (PFDM) and coupled to a cloud of strings (CS). The metric function combines the magnetic monopole charge from nonlinear electrodynamics, the PFDM…

We are fitting dynamics of electrically neutral hot-spot orbiting around Sgr A* source in Galactic center, represented by various modifications of the standard Kerr black hole (BH), to the three flares observed by the GRAVITY instrument on…

There is growing evidence that every galaxy with a considerable spheroidal component hosts a supermassive black hole (SMBH) at its center. Strong correlations between the SMBH and the spheroidal component suggest a physical connection…

We show that the mass of a self-interacting dark matter candidate, specifically a Dirac fermion, can be generated by composite dynamics, with a light scalar mediator emerging alongside the Higgs itself as composite particles. These novel…

The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact…

We show that the gap in the compactness between black holes and neutron stars witnessed in general relativity may be vanishing in Ho\v{r}ava-Lifshitz (HL) gravity. Assuming a fermion equation-of-state for simplicity, and solving the…

The Galactic Center black hole Sgr A* shows significant variability and flares in the submillimeter, infrared, and X-ray wavelengths. Owing to its exquisite resolution in the IR bands, the GRAVITY experiment for the first time spatially…

Rotating fermion-boson stars are hypothetical celestial objects that consist of both fermionic and bosonic matter interacting exclusively through gravity. Bosonic fields are believed to arise in certain models of particle physics describing…

The existence of black holes remains open to doubt until other conceivable options are excluded. With this motivation, we consider a model of a compact star in which most of the mass consists of dark particles of some kind, and a small…

Observations of the S-stars, the cluster of young stars in the inner 0.1 pc of the Galactic Center, have been crucial in providing conclusive evidence for a supermassive black hole at the center of our galaxy. Since some of the stars have…

Two forms are suggested for the energy-momentum source term associated with an aggregate of dark matter (with the properties described in Paper I). Both have large pressure-like components which dominate the density terms. Using one form a…

Understanding the origin and evolution of supermassive black holes (SMBH) stands as one of the most important challenges in astrophysics and cosmology, with little current theoretical consensus. Improved observational constraints on the…

With the recent release of the second gravitational-wave transient catalogue (GWTC-2), which introduced dozens of new detections, we are at a turning point of gravitational wave astronomy, as we are now able to directly infer constraints on…

Stellar-remnant black holes (BH) in dense stellar clusters comprise a natural setup to trigger general-relativistic (GR) inspiral and merger of binary black holes (BBH), detectable by the LISA and the LIGO-Virgo, through dynamical…

After the amazing discoveries by the GRAVITY collaboration in the last few years on the star S2 orbiting the black hole Sgr A* in the center of the Milky Way, we present a detailed investigation of the impact of gravitational lensing on the…

In this work, we explore the possible scenario of strange stars admixed with fermionic or bosonic dark matter. For the description of the ``visible'' sector, we use a specific phenomenological quark model that takes into account in-medium…

The compact dark objects with very large masses residing at the centres of galaxies are believed to be black holes. Due to the gravitational lensing effect, they would cast a shadow larger than their horizon size over the background, whose…

Several observations suggest the existence of super-massive black holes (SMBH) at the centers of giant galaxies. However the mechanism under which these objects form remains non completely understood. In this work we review an alternative…