ABSTRACT The motion data of the S-stars around Galactic Centre gathered in last 28 yr imply that Sgr A* hosts a supermassive compact object about $4 \times 10^6\, {\rm M}_{\odot }$, result awarded with Nobel Prize Physics 2020. A non-rotating black hole (BH) nature has been uncritically adopted since S-star orbits agree Schwarzschild geometry geodesics. orbit S2 served as test general relativity predictions such gravitational redshift and relativistic precession. central BH model is,...

Long and short gamma-ray bursts (GRBs) are thought to arise from different unrelated astrophysical progenitors. The association of long GRBs with supernovae (SNe) the difference in distributions galactocentric offsets within their host galaxies have often been considered strong evidence origins. result collapse single massive stars, while come mergers compact-object binaries. Our present study challenges this conventional view. We demonstrate that observational properties, such as SNe...

The concept of the irreducible mass (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>M</a:mi><a:mi>irr</a:mi></a:msub></a:math>) has led to mass-energy (<b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mi>M</b:mi></b:math>) formula a Kerr black hole (BH), in turn leading its surface area <c:math...

We investigate the distribution of dark matter in galaxies by solving equations equilibrium a self-gravitating system massive fermions ('inos') at selected temperatures and degeneracy parameters within general relativity. Our most solutions show, as function radius, segregation three physical regimes: (1) an inner core almost constant density governed degenerate quantum statistics; (2) intermediate region with sharply decreasing followed extended plateau, implying corrections; (3)...

The properties of uniformly rotating white dwarfs (RWDs) are analyzed within the framework general relativity. Hartle's formalism is applied to construct internal and external solutions Einstein equations. dwarf (WD) matter described by relativistic Feynman–Metropolis–Teller equation state which generalizes that Salpeter taking into account finite size nuclei, Coulomb interactions as well electroweak equilibrium in a self-consistent fashion. mass M, radius R, angular momentum J, eccentricity...

It is understood that the supernovae (SNe) associated with gamma-ray bursts (GRBs) are of Type Ib/c. The temporal coincidence GRB and SN continues to represent a major enigma Relativistic Astrophysics. We elaborate here, from earlier paradigm, concept induced gravitational collapse essential explain GRB–SN connection. specific case close (orbital period <1 hr) binary system composed an evolved star neutron (NS) companion considered. evaluate accretion rate onto NS material expelled explosion...

We construct equilibrium configurations of uniformly rotating neutron stars for selected relativistic mean-field nuclear matter equations state (EOS). compute, in particular, the gravitational mass ($M$), equatorial (${R}_{\text{eq}}$) and polar (${R}_{\text{pol}}$) radii, eccentricity, angular momentum ($J$), moment inertia ($I$) quadrupole (${M}_{2}$) stable against shedding secular axisymmetric instability. By constructing constant frequency sequence $f=716\text{ }\text{ }\mathrm{Hz}$...

[Abridged] The S-stars motion around the Galactic center (Sgr A*) implies existence of a compact source with mass about $4\times 10^6 M_\odot$, traditionally assumed to be massive black hole (BH). Important for any model is explanation multiyear, accurate astrometric data S2 and challenging G2: its post-pericenter velocity decelerates faster than expected from Keplerian orbit putative BH. This has been reconciled in literature by acting on G2 drag force an accretion flow. Alternatively, we...

We show that the gravitomagnetic interaction of a Kerr black hole (BH) with surrounding magnetic field induces an electric accelerates charged particles to ultra-relativistic energies in vicinity BH. Along BH rotation axis, these electrons/protons can reach even thousands PeV, so stellar-mass BHs long gamma-ray bursts (GRBs) and supermassive active galactic nuclei (AGN) contribute ultrahigh-energy cosmic rays (UHECRs) thorough this mechanism. At off-axis latitudes, accelerate hundreds GeV...

SGR 0418$+$5729 is a “Rosetta Stone” for deciphering the energy source of Soft Gamma Ray Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs). We present model based on canonical physics astrophysics SGRs AXPs powered by massive highly magnetized rotating white dwarfs (WDs), in total analogy with pulsars neutron stars (NSs). predict lower limit its spin-down rate, $\dot{P}~\geq~L_{\rm X} P^3/$(4$\pi^2 I$) $=$ 1.18 $\times$ 10$^{-16}$, where $I$ moment inertia WD. show that occurrence glitch...

The recent formulation of the relativistic Thomas-Fermi model within Feynman-Metropolis-Teller theory for compressed atoms is applied to study general white dwarf equilibrium configurations. equation state, which takes into account \beta-equilibrium, nuclear and Coulomb interactions between nuclei surrounding electrons, obtained as a function compression by considering each atom constrained in Wigner-Seitz cell. contribution quantum statistics, weak, nuclear, electromagnetic determination...

We study static, spherically symmetric, self-gravitating systems minimally coupled to a scalar field with U(1) gauge symmetry: charged boson stars. find numerical solutions the EinsteinMaxwell equations relativistic Klein-Gordon equation. It is shown that bound stable configurations exist only for values of coupling constant less than or equal certain critical value. The metric coefficients and relevant physical quantities such as total mass charge, turn out be in general functions radial...

ABSTRACT Following the induced gravitational collapse (IGC) paradigm of gamma-ray bursts (GRBs) associated with type Ib/c supernovae, we present numerical simulations explosion a carbon–oxygen (CO) core in binary system neutron-star (NS) companion. The supernova ejecta trigger hypercritical accretion process onto NS thanks to copious neutrino emission and trapping photons within flow. We show that temperatures 1–10 MeV develop near surface, hence electron–positron annihilation into neutrinos...

The induced gravitational collapse (IGC) paradigm has been successfully applied to the explanation of concomitance gamma-ray bursts (GRBs) with supernovae (SNe) Ic. progenitor is a tight binary system composed by carbon-oxygen (CO) core and neutron star (NS) companion. explosion SN leads hypercritical accretion onto NS companion which reaches critical mass, hence inducing its black hole (BH) consequent emission GRB. first estimates this process were based on simplified model parameters...

ABSTRACT There is mounting evidence for the binary nature of progenitors gamma-ray bursts (GRBs). For a long GRB, induced gravitational collapse paradigm proposes as progenitor, or “in-state,” tight system composed carbon–oxygen core (CO <?CDATA ${}_{\mathrm{core}}$?> ) undergoing supernova explosion that triggers hypercritical accretion onto neutron star (NS) companion. short GRB (S-GRB), an NS–NS merger traditionally adopted progenitor. We divide and S-GRBs into two subclasses, depending...

We propose that the "inner engine" of a type I binary-driven hypernova (BdHN) is composed Kerr black hole (BH) in non-stationary state, embedded uniform magnetic field $B_0$ aligned with BH rotation axis, and surrounded by an ionized plasma extremely low density $10^{-14}$~g~cm$^{-3}$. Using GRB 130427A as prototype we show this acts sequence "elementary impulses". Electrons are accelerated to ultra-relativistic energy near horizon and, propagating along polar $\theta =0$, they can reach...

Abstract Nonlinear structure formation for fermionic dark matter particles leads to density profiles with a degenerate compact core surrounded by diluted halo. For given fermion mass, the has critical mass that collapses into supermassive black hole (SMBH). Galactic dynamics constraints suggest ∼100 keV/ c 2 fermion, which ∼10 7 M ⊙ mass. Here, we show baryonic (ordinary) accretion drives an initially stable SMBH and determines accreted threshold induces it. Baryonic gas ρ b velocity v...

The Feynman, Metropolis and Teller treatment of compressed atoms is extended to the relativistic regimes. Each atomic configuration confined by a Wigner-Seitz cell characterized positive electron Fermi energy. non-relativistic assumes point-like nucleus infinite values energy can be attained. In there exists limiting configuration, reached when radius equals nucleus, with maximum value $(E_e^F)_{max}$, here expressed analytically in ultra-relativistic approximation. corrections given...

The joint X and gamma-ray observations of GRB 090618 by a large number satellites offer an unprecedented possibility testing crucial aspects theoretical models. In particular, it allows us to test (a) the formation optically thick e+e- baryon plasma self-accelerating Lorentz factors in range 200 < g 3000; (b) its transparency condition with emission component 10^{53-54} baryons TeV region (c) collision these circumburst medium clouds, characterized dimensions 10^{15-16} cm. addition, new...

Binary-driven hypernovae (BdHNe) within the induced gravitational collapse paradigm have been introduced to explain energetic (E_{iso}≳10^{52} erg), long gamma-ray bursts (GRBs) associated with type Ic supernovae (SNe). The progenitor is a tight binary composed of carbon-oxygen (CO) core and neutron-star (NS) companion, subclass newly proposed "ultrastripped" binaries. CO-NS short-period orbit causes NS accrete appreciable matter from SN ejecta when CO collapses, ultimately causing it black...

Abstract We show that the high-energy emission of GRBs originates in inner engine : a Kerr black hole (BH) surrounded by matter and magnetic field $$B_0$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>B</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:math> . It radiates sequence discrete events particle acceleration, each energy $${{\mathscr {E}}} = \hbar \,\varOmega _{\mathrm{eff}}$$...

The nature of dark matter (DM) is one the most relevant questions in modern astrophysics. We present a brief overview recent results that inquire into possible fermionic quantum DM particles, focusing mainly on interconnection between microphysics neutral fermions and macrophysical structure galactic halos, including their formation both linear non-linear cosmological regimes. discuss general relativistic Ruffini–Argüelles–Rueda (RAR) model galaxies, its applications to Milky Way,...