Guatemala is a small country located in Central America, which has a great legacy of one of the biggest cultures of the American Continent, the Mayas, a civilization with a great scientific legacy and that developed a great understanding of astronomy. They measured the time based on astronomical events predicting solar eclipses and their calendar is one of the most precise ever developed....

Each civilization, since immemorial times, has developed their own culture, their own ethos and their own worldview. It was no different in the Inka culture. The man, in the different regions of the Inca empire (in Quechua, Tawantinsuyo), in his evolutionary process, also developed customs, habits, ways of being, ways of behavior. Finally, they sought to answer fundamental questions in the...

Northeast of Mexico City are the extant remains of one of the largest urban centers of the ancient world. Built long before, the Aztecs later adopted the site and named it "the place where the gods were created“, or Teotihuacan. They considered this to be the location where time began.

Elements of the vast complex were created with astronomical alignments, a common practice with many ancient...

The Pre-Hispanic city of Teotihuacán was the scene of multiple social dynamics, in which groups originating from various regions of Mesoamerica were involved. This is because the cosmopolitan nature of the city allowed the daily coexistence of people who came to it, either for reasons of exchange of objects and goods, such as the religious, political and cultural prestige that distinguished...

Almost fifty years after the paper "Introducing the Black Hole" by Ruffini and Wheeler and the Black Hole (BH) mass energy formula by Christodoulou, Ruffini and Hawking, we can finally assert that we have been observing the moment of creation of a BH in the BdHN I in GRB 190114C, GRB 130427A, GRB 160509A and GRB 160625B, with the corresponding rotational energy extraction process. The first...

In strongly magnetized plasmas of DA white dwarfs, where the magnetic field B could be as high as ~ (10$^2$ – 10$^5$) Tesla, electrons move along strongly helical trajectories. The allowance for helical trajectories of plasma electrons dramatically changes the Stark width of hydrogen spectral lines compared to all previous calculations. We show analytically that without allowance for this...

Going beyond the fuzzy dark matter model, we present the construction of multi-state configurations of the Gross-Pitaevskii-Poisson system that rules the dynamics of this matter, their stability, mechanism of formation and application in galactic astrophysics.

The localization of energy-momentum for a four-dimensional charged, static, and spherically symmetric, non-singular black hole solution that asymptotically behaves as a Reissner-Nordström solution, is studied. The space-time geometry is distinguished by a distribution function entering the mass function m(r). The non-singular character of the metric is warranted by the coupling of general...

We propose and test a fairly simple idea that could account for the blazar sequence: all jets are launched with similar energy per baryon, independently of their power. For instance, FSRQs, the most powerful jets, manage to accelerate to high bulk Lorentz factor, as observed in the radio. As a result, the emission region will have a rather modest magnetization which will induce a steep...

In this theoretical study, we establish a correlation between the neutron skin thickness and the nuclear symmetry energy for the even-even isotones for magic neutron N = 20, 40, 82, 126, 172 (expected) within self-consistent relativistic mean-field formalism for non-linear NL3* and density-dependent DD-ME2 parameter sets [1-3]. The local density approximation is used to formulate the symmetry...

We study the magnetic field dependence of the masses of pions, diquarks and nucleons in the context of the Nambu-Jona-Lasinio model. Eigenvalue equations associated with charged particles are obtained using the Ritus formalism. In this way we fully take into account the existence of non-vanishing Schwinger phases. Our results are compared with those available in the literature obtained using...

We analyse physical grounds for large braking indices of some young radio pulsars and investigated four hypothesis explaining origin of large braking indices: (1) binarity, (2) magnetic field decay, (3) evolution of the obliquity angle, and (4) complicated multipole structure of the poloidal magnetic field. We find that the magnetic field decay is the only plausible explanation for the...

The formation of neutron stars (NSs), both from collapses of massive stars and mergers of compact objects, can usually be indicated by a bright transient emission that is generated from the explosively-ejected material. In particular, as the newborn NSs can rotate very quickly and have a sufficiently high magnetic field, the spin-down of the NSs would provide a remarkable amount of energy to...

Theoretical models and observations suggest that primordial stellar Black Holes (Pop III-BHs) were prolifically formed in HMXBs, which are powerful jet-sources of synchrotron radiation called Microquasars (MQs). Possible signatures of large populations of BH-HMXB-MQs at cosmic dawn are: a synchrotron cosmic radio background (CRB) observed with ARCADE 2, and the unpredicted large excess...

We are now able to simulate much of the early universe from the time of the Electro-Weak Phase Transition through the end of primordial nucleosynthesis. This simulation is performed using a General Relativistic Magnetohydrodynamic code based on the Cactus framework. It solves both the relativistic magnetohydrodynamic equations and Einstein’s equations of General Relativity. As a result, it...

Relativistic jets in active galactic nuclei start as a Poynting flux produced in the ergosphere of rapidly rotating black holes. However, at distances of a few tens of gravitational radii from the black hole these jets produce synchrotron and inverse Compton radiation, a clear indication that they have a significant content of charged particles. In this talk I discuss the origin of such...

In this talk we present current cosmological results about Modified and Teleparallel Gravity Cosmology. We demonstrate that according the current astrophysical data (CC+Pantheon+BAO+GW samplers with late universe measurements SH0ES+H0LiCOW) these theories can provide another interpretation to the oscillatory behaviour of the dark energy equation of state when applied to late times and...

The model of ultra light bosons to conform the dark matter of the Universe has been under strong scrutiny in the last two decades, and has of lately become an alternative reference model to the cold dark matter one of the standard cosmological model. In this talk we will present the general results of the model and a summary of the observations that can constrain its physical parameters. In...

We consider spacetime foliation, at every given moment according to canonical observers, each with its speed at that moment. Consider a black hole spacetime as a spacetime with horizon. The Universe in that sense look like a sequence of frozen moments like a cartoon movie. The Rindler observer would analyze the ADM formalism as if the shift function Ni equal zero. Therefore, the normal vector...

We study the spheroidal magnetized Quark and Bose–Einstein Condensate (BEC) Stars. The former are supposed composed by strange quark matter while the later by the pairing of two-neutrons forming an interacting spin-one bosons. We calculate the equation of states (EoS) of the magnetized strange stars matter using Bag model while the corresponding EoS for magnetized BEC stars are doing...

We investigate the stability and $e^+e^-$ pair creation of supercritically charged superheavy nuclei, $ud$QM nuggets, strangelets, and strangeon nuggets based on the Thomas-Fermi approximation. The model parameters are fixed by reproducing masses and charge properties of these supercritically charged objects reported in earlier publications. It is found that $ud$QM nuggets, strangelets, and...

In this talk, I analyze the dynamical evolution of a black hole that is immersed in a universe that goes through a classical bounce. The black hole is represented by the McVittie metric, an exact solution of Einstein Field Equations for an inhomogeneity embedded in a Friedmann-Lemaître-Robertson-Walker cosmological background. I present a full analysis of the causal structure of the spacetime....

We study the anisotropic neutrino emission from the core of neutron stars induced by the star's magnetic field. We model the core as made out of a magnetized ideal gas of strange quark matter and implement the conditions for stellar equilibrium in this environment. The calculation is performed without resorting to analytical simplifications and for temperature, density and magnetic field...

We model the 3PCF of General Relativity (GR) and a representative model of Modified Gravity (f(R)) using Cosmological Perturbation Theory and compare it with the non-linear evolution of N-body simulations.

Several studies suggest that active galactic nuclei (AGN) play a significant role in the cosmological evolution of their host galaxies and dark matter halos. There is considerable evidence that the formation and evolution of the central AGN and the diffuse gas in the halo are coupled together by the activity of the supermassive blackhole (SMBH), usually termed as AGN feedback in the...

In this paper we have investigated the gravitational lensing phenomenon in the strong field regime for a regular, charged, static, non-linear black hole having a electrodynamics source. We have obtained the angle of deflection and compared it to a Schwarzschild black hole and Reissner Nordstrom black hole with similar properties. We have also done a graphical study of the relativistic image...

The fast shocks in supernova remnants are known to accelerate particles to extremely high energies. The acceleration process is closely tied to the magnetic field structure in the shock region. This, in turn, can be modified considerably by the shock. Synchrotron emission from the shock regions provides crucial details about the magnetic field strength and orientation through its polarization....

One of the most intriguing questions in the astrophysics of neutron stars is whether their interiors harbour deconfined quark matter. With the first multi-messenger observation of a binary neutron star merger (GW170817) new constraints became available for masses and radii of neutron stars. In this lecture, I will discuss what we may infer for their mass and the central density at the onset of...

The Pierre Auger Observatory, covering an area of 3000 km$^2$ is currently the larges observatory to study the highest energy cosmic rays, with energies above $10^{18}$ eV. The main part observatory consists of a surface detector with about 1600 stations, spaced 1.5 km apart, and 4 fluorescence detector sites with a total of 17 telescopes, overlooking the surface detector. We will start our...

Surveys have shown radio-loud (RL) quasars constitute 10%-15% of the total quasar

population and rest are radio-quiet (RQ). However, it is unknown if the radio-loud fraction or RLF (RL quasars/Total quasars) remains consistent among different parameter spaces. This study shows that RLF increases for increasing full width half maximum (FWHM) velocity of the Hβ and MgII broad emission line. Our...

In this discussion, we have analysed the thermo-dynamical effects of a cosmological model using Einstein Theory. To study the model, we have considered several time varying dark energy states in two different assumptions, from which we found a phantom phase during spatially open universe for Λ ∝ 𝑎 𝑡−𝑛 and all remaining results indicates a quintessence phase. The temperature and entropy density...

An extension of the Standard Model (SM) is studied, in which two new vector bosons are introduced, a first boson (Z') coupled to the SM by the usual minimal coupling, producing an enlarged gauge sector in the SM and a second boson field, in the dark sector of the model, remains massless and originates a dark photon, in a hybrid mixing scenario based on a combined Higgs and Stueckelberg...

We study the quantum magnetic collapse of a partially bosonized npe-gas and obtain that this type of collapse might be one of the mechanisms behind matter expulsion out of compact objects. We check also that this gas might form a stable stream of matter whose collimation is due to its strong self-generated magnetic field. Possible astrophysical applications of these results, in particular...

We studied thermodynamic aspects of modified Rastall gravity; recently, we proposed a modified Rastall gravity related to unimodular gravity. In this context, we study the non-conservation of the energy-momentum tensor; we develop covariant formalism of the first and second laws of thermodynamics. The second law implies a non-zero entropy flow and it is necessary to introduce particle...

The stellar Initial Mass Function (IMF) appears to be close to universal within the Milky Way galaxy. However, it is strongly suspected to be different in the primordial Universe, where molecular hydrogen cooling is less efficient and the gas temperature can be higher by a factor of 30. In between these extreme cases, the gas temperature varies depending on the environment, metallicity and...

The relation between gravitational memory effects and Bondi-Metzner-Sachs symmetries of the asymptotically flat spacetimes is studied in the scalar-tensor theory. For this purpose, the solutions to the equations of motion near the future null infinity are obtained in the generalized Bondi-Sachs coordinates with a suitable determinant condition. It turns out that the Bondi-Metzner-Sachs group...

The HAWC gamma ray observatory situated at 4200 m altitude in the Volcan Sierra Negra, Central Mexico, has observed several sources that emit gamma rays of energies greater than 50 TeV. What are they? What is the production mechanism? How do they look in other frequencies? How do they relate to the sources of energetic cosmic rays? These are some of the questions that will be discussed.

The scientific potential of a wide field of view, and very high duty cycle, ground based gamma ray detector has been demonstrated by the current generation of instruments, such as HAWC and ARGO, and will be further extended in the Northern hemisphere by LHAASO. Nevertheless, no such instrument exists in the southern hemisphere yet, where a great potential lies uncovered for the mapping of...

The long-awaited detection of a gravitational wave (GW) from the merger of a binary neutron star (BNS) in August 2017 (GW170817) marked the beginning of the new field of multi-messenger gravitational wave astronomy. By exploiting the extracted tidal deformations of the two neutron stars from the late inspiral phase of GW170817, it was possible to constrain several global properties of the...

The possible detection of a compact object in the remnant of SN 1987A presents an unprecedented opportunity to follow its early evolution. The suspected detection stems from an excess of infrared emission from a dust blob near the compact object's predicted position. The infrared excess could be due to the decay of isotopes like 44Ti, accretion luminosity from a neutron star or black hole,...

We review the properties of the strongly interacting quark-gluon plasma (QGP) created in heavy-ion collisions at ultrarelativistic energies, i.e. out-of equilibrium, and compare them to the equilibrium case.

The description of the strongly interacting (non-perturbative) QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is...

Based on quantum mechanical framework for the minimal length uncertainty, we demonstrate that the generalized uncertainty principle (GUP) parameter - on one hand - could be best constrained by recent gravitational waves observations, and - on other hand - suggest modified dispersion relations (MDRs) to calculate the difference between the group velocity of gravitons and that of photons....

When minimal length uncertainty emerging from generalized uncertainty principle (GUP) is thoughtfully implemented, it is of great interest to consider its impacts on Einstein’s gravitational field equations (EFE) and to find out whether the corresponding modification in the metric manifests properties of quantum geometry due to quantum gravity. GUP takes into account the gravitational impacts...

Static (not stationary) solutions of the Einstein-Klein-Gordon (EKG) equations including matter are obtained for real scalar fields. The scalar field interaction with matter is considered. The introduced coupling allows the existence of static solutions in contraposition with the case of the simpler EKG equations for real scalar fields and gravity. Surprisingly, when the considered matter is a...

With the discovery of gravitational waves from merging pairs of massive black holes, the interest in the question of whether Primordial Black Holes (PBHs) could constitute the Dark Matter (DM) has recently been revived. In this talk, I will review the different mechanisms for (DM) PBHs formation with a focus on inflation which can source the required large density fluctuations for PBHs...

A new code to simulate special relativistic hydrodynamic flows on supercomputer architectures with distributed memory is described. The code is based on a combination of Godunov's method and a piecewise parabolic method with a local stencil. This approach has good conservation properties, correctly reproduces shock waves, and ensures high accuracy on smooth solutions and low dissipation on...

In Einstein’s general relativity, gravity is mediated by a massless metric field. The extension of general relativity to consistently include a mass for the graviton has profound implications for gravitation and cosmology. Salient features of various massive gravity theories can be captured by Galileon models, the simplest of which is the cubic Galileon. The presence of the Galileon field...

Late time accelerated expansion of the Universe is well documented in the literature. An exotic matter, characterized by negative pressure is considered to be the driving force behind this late time acceleration of the Universe and it is dubbed as dark energy (DE). The negative pressure p leads to negative equation of state (EoS) parameter w = p/ρ, where ρ is the density of the Universe. In...

We study an impact of asymmetric dark matter on properties of the neutron stars and their ability to reach the two solar masses limit, which allows us to present a new range of masses of dark matter particles and their fractions inside the star. Our analysis is based on the observational fact of the existence of three pulsars reaching this limit and on the theoretically predicted reduction of...

Magnetars are a kind of pulsars powered mainly by superhigh magnetic fields. They are popular sources with many unsolved issues in themselves, but also linked to various high-energy phenomena, such as Quasi-periodic oscillation, giant flares, fast radio bursts and super-luminous supernovae. In this presentation, combining with the latest EoSs, we first introduce the eigen equations of Ohmic...

While the large scale structures formation is dominated by Cold Dark Matter (CDM) field evolution, we generally have only access to baryonic tracer like galaxies. In particular, Mexico is involved in three of the most important galaxy surveys of next decade: DESI, SDSS-V and LSST. The usual method is to link the galaxy distribution to the CDM density field using a linear bias. We propose to...

The equation of state (EoS) of strongly interacting matter for finite chemical potentials cannot be calculated from first principles (lattice QCD) so one have to rely on effective theories like the Polyakov-Nambu-Jona-Lasinio model. Recently it has been shown that they can reproduce the lattice calculations at vanishing chemical potential and provide therefore a solid basis for the...

In this talk we derive closed general relativistic formulas for the mass M and the spin parameter a of a Kerr black hole in terms of observational data: the red- and blue-shifts of photons emitted by massive particles (stars or gas) geodesically orbiting around the black hole, and their respective orbital radius. It turns out that given a set of two (three) stars revolving around the Kerr...

Quark matter surface tension plays a key role in the understanding of neutron star (NS) interiors. However, despite its relevance for NS physics, the surface tension is still poorly known for quark matter. We focus on the thermodynamic conditions prevailing in NSs, hot lepton-rich protoneutron stars (PNSs), and binary NS mergers. We explore the role of temperature, baryon number density,...

In 2015 the first detection of gravitational waves was made, gravitational waves from the violent collision of two black holes. This collision sent waves through space-time as Einstein predicted. This detection was made possible by many advances in measurement technology, mainly vibration isolation for the detector optics; at 10 Hz, the motion of the laser interferometer detector mirrors is at...

Local galaxies are the endpoint of all cosmological evolution: to understand how galaxies evolve through cosmic time, we need a careful characterization of galaxy structures in the local universe. The Spitzer Survey of Stellar Structure in Galaxies (S4G) is one of the major legacy surveys of the post-cryogenic campaign of the Spitzer Space Telescope. With deep mid-infrared (3.6/4.5um) imaging...

During this talk I will present a novel proposal to explain cosmic inflation in the Universe with the following features: (i) its vacuum spectrum solely consists of a graviton and is ghost-free, (ii) it possesses well-behaved black hole solutions which coincide with those of Einsteinian cubic gravity, (iii) its cosmology is well-posed as an initial value problem and, most importantly, (iv) it...

In this talk I will present a systematic analysis of dark matter production during post-inflationary reheating. The damped oscillations of the inflation as it decays, the thermalization rate of its decay products, and the evolution of the temperature of the subsequently thermalized radiation determine the production rate of dark matter, and they are in turn dependent on the shape of the...

In this work, we calculate the decay rates of some resonances that can be considered as hybrid mesons. This study was carried out using the constituent gluon model. We specifically studied the resonances $\pi_1(1400)$ and $\pi_1(1600)$, since the lightest hybrid meson, with quantum numbers $J^{PC}$ = $1^{−+}$, is expected to be in this region of hadronic spectrum. The constituent gluon model...

Pulsars emit pulsed radiation in well-defined frequencies. In the canonical model, a pulsar is assumed to be a rotating, highly magnetized sphere made mostly of neutrons that has a magnetic dipole misaligned with respect to its rotation axis, which would be responsible for the emission of the observed pulses. The measurement of the pulse frequency and its first two derivatives allows the...

In today’s scenario, going beyond Einstein’s theory of gravity leads us to some more complete and modified theories of gravity. One of them is the f(R,T) gravity in which R is the Ricci scalar, and T is the trace of energy-momentum tensor. A well-motivated f(R,T) gravity model, f(R,T) = R + αRT where α is the model parameter is considered here. In this work, we studied the strong energy...

This work starts from a toy model for inflation in a class of modified theories of gravity in the metric formalism. Instead of the standard procedure -- assuming a non-linear Lagrangian f(R) in the Jordan frame -- we start from a simple φ$^2$ potential in the Einstein frame and investigate the corresponding f(R) in the former picture. The addition of an ad-hoc Cosmological Constant in the...

The detection of gravitational waves and accompanying EM signals from a binary neutron star merger, GW 170817 was one of the most remarkable scientific achievements of the last decade. The discovery confirmed numerous long standing predictions, ranging from the mergers being the cosmic foundries of r-process elements to the origin of short gamma-ray bursts. It also revealed the potential of...

An outlook of different aspects of the incidence of magnetic fields on early universe events is presented. The events we will focus on include inflation and the electroweak phase transition. The guideline of the study is mainly the effect of the magnetic field on the effective potential of phase transitions and the decay process of the field leading the phase transition to other fields. We...

Gravitational waves astrophysics is a new and promising field of research of the Universe. In contrast to the observations of the electromagnetic waves (radio waves, visible light, X rays and gamma), which are the main source of our current knowledge, we ''listen" to the Universe by registering minor disturbances of the space time curvature using the LIGO and Virgo laser interferometric...

One of the most prominent AGNs, the ultrasoft Narrow-Line Seyfert 1 Galaxy 1H 0707-495, has been observed with eROSITA as one of the first CAL/PV observations on October 13, 2019 for about 60.000 seconds. 1H 0707-495 is a highly variable AGN, with a complex, steep X-ray spectrum, which has been the subject of intense study with XMM- Newton in the past. Large amplitude variability with a factor...

Cosmology in the XXI century is experiencing a "Golden Age", with observations and theoretical models contributing to a large-scale description of the Universe. The current view is that it can be well described by the so-called Lambda-CDM model, but some open problems challenge physics and cosmology, including the origin and properties of so-called dark energy. The so-called baryonic acoustic...

A numerical rotating neutron star solver is used to study the temporal evolution of accreting neutron stars using a multi-polytrope model for the nuclear equation of state named ACB5. The solver is based on a quadrupole expansion of the metric, but confirms the results of previous works, revealing the possibility of an abrupt transition of a neutron star from a purely hadronic branch to a...

We study the properties of photon propagation both in QED vacuum and medium, taking into account radiative corrections, in an external magnetic field. We explore possible applications of the results in an astrophysical context.

In this work we study the influences of the dark matter fermion mass on the structure of the hybrid star. We fixed the Fermi momentum of dark matter and considered the mass of dark matter from 0.1 GeV to 100 GeV, since the mass of dark matter is more uncertain than its density approximation related to ordinary matter. Further, we used the Maxwell construction to make the phase transition...

In this work we investigate the diffractive gluon jet production in electron-ion collisions at the energies of the EIC, LHeC, HE-LHeC and FCC-eA, assuming that the diffractive mass is much larger than the photon virtuality. In addition, we apply a model inspired in the GBW parametrization to describe the dipole amplitude, showing that the diffractive cross section is highly sensitive to the...

We give an alternative way for deducing the Hawking-Bekenstein black hole temperature and entropy by using the Heisenberg uncertainty principle. We consider as known the black hole mass as M and consequently its energy. Quantities as temperature T and entropy S can be found under the hypothesis that incoming radiation and matter leads to a thermodynamic equilibrium state. Obviously this is not...

We calculate the axial ring-down frequencies of the merger of two black holes, using a modified version of the pseudo-complex General Relativity (pc-GR) and comparing it with the standard General Relativity (GR).

In the present work we show that it is possible to model galactic dark matter from nonlinear scalar field theories coupled to the gravity sector. In order to obtain analytical solutions for the scalar fields we consider a spherically symmetric space-time. We also assume a theoretical framework where dark matter consists of a complex scalar field, which is responsible for producing galactic...

In this contribution, we investigate the possibility of a third family of compact stars under different scenarios. First, we will focus on the microscopic description of stars and discuss how different properties of matter can influence the rising of twin stars. For doing so, we carry out an analysis of different parameters used to describe hadronic and quark matter with relativistic mean...

We study the effects of large scale magnetic field on the dynamics of charged particles near a rotating black hole. We consider a scenario in which the initially neutral particles on geodesic orbits in the equatorial plane are destabilized by a charging process. Fraction of charged particles are then accelerated out of the equatorial plane and then follow jet-like trajectories with...

As for strong condensed matter, normal nuclei are 2-flavored (u, d), but what if matter is squeezed so great that nuclei come in close contact to form giant strong matter? The latter could be 3-flavored (u, d, s) because of leptonic asymmetry (i.e., electron and positron), since both the strong and the weak interactions play an important role there. Therefore, one should focus on three flavors...

We study in detail the nuclear aspects of a neutron-star merger in which deconfinement to quark matter takes place. For this purpose, we make use of the Chiral Mean Field (CMF) model, an effective relativistic model that includes self-consistent chiral symmetry restoration and deconfinement to quark matter and, for this reason, predicts the existence of different degrees of freedom depending...

One of the most important open questions in cosmology today is the understanding of the accelerated expansion of the Universe. Spectroscopic surveys provided a unique opportunity to explore the expansion history of the Universe as well as to measure the growth of structure through the analysis of the large-scale structure in the Universe. Cosmic Acceleration can be explained by either...

A brief review on algebraic extensions of General Relativity will be given. After a short summary of first attempts by Max Born and Albert Einstein, all possible algebraic extensions will be discussed, with the pseudo-complex extension left as the only viable one, because it does not contain ghost solutions. Some predictions of the pseudo-complex extension are given.

In this work a method to design two mechanical modes transducers for spherical resonant mass gravitational wave detectors is presented. Applied for SCHENBERG detector that uses microwave multiparametric sensors. The detector has 17 mechanical modes and more 6 electromagnetic modes for the microwave cavities. Here these aspects of the mechanical design that should allow amplification in...

Cyg X-3 is the famous binary system containing a black hole. It is actively studied through the wide range of electromagnetic spectrum from radio band up to ultrahigh energies. Cyg X-3 has long been considered as an object for very high energy gamma-ray observations. We present the results of more than 20-year-long studies of Cyg X-3 in the range of 800 GeV–100 TeV with the SHALON telescope....

The $^{12}$C+$^{12}$C fusion reaction holds a great significance in the later phases of stellar evolution. To get involved in this evolution, one must understand the corresponding fusion-fission dynamics and reaction characteristics. In the present analysis, we have studied the fusion cross-section along with the S-factor for this reaction using the well-known M3Y and recently developed R3Y...

Properties of galaxies, such as color, age and star formation activity, appear to be associated with the environment in which they are immersed. To investigate how environment influences galaxy evolution, astronomers study galaxies in dense regions (i.e., galaxy clusters), where the environmental effects become more intense and evident. However, to study how the environment-galaxy relation is...

The hypothesis that one or more biodiversity drops in the Phanerozoic eon, evident in the geological record, might have been caused by the most powerful kind of stellar explosion so far known (Gamma Ray Bursts) has been discussed in several works. These stellar explosions could have left an imprint in the biological evolution on Earth and in other habitable planets. In this work we calculate...

Several studies have been dedicated to study the nature of dark matter (DM) and to try to discover its origin. Different approaches have been employed to understand how DM interacts and what are possible mechanisms to detect it. Theories beyond the Standard Model of Elementary Particles (SM) could achieve this by employing effective, simplified, or more complete models. Direct, indirect, and...

The formation of supermassive black holes (SMBHs) and their co-evolution with the host galaxy is poorly understood in the early Universe. How is the growth of the stellar bulge related to the growth of the SMBH? Looking at the coexistence of star formation activity and SMBHs in high redshift galaxies is critical to address this question.

At high redshifts, it is hard to study galaxies as...

The origin of neutrino masses heralds new physics. Some theories that explain small neutrino masses, predict the existence of sterile neutrinos. Observationally, there is no evidence that neutrinos cause attractive gravity. Exploring a new idea, we study constraints posed by data as to what if sterile neutrinos cause repulsive gravity. We use an effective negative gravitational constant (-G')...

One of the most straightforward ways to explain the hard X-ray spectra observed in X-ray binaries is to assume that comptonization of soft photons, originated in the disk, is occurring. The region in which such comptonization takes place, called the corona, is commonly characterized by only two parameters: its thermal energy $kT$ and its optical depth $\tau$. Thus, hard X-ray spectra analysis...

The behavior of $\pi^0$ meson properties in the presence of a uniform external magnetic field is studied in the context of a nonlocal extension of the Polyakov-Nambu-Jona-Lasinio model which predicts the existence of inverse magnetic catalysis at finite temperature. The analysis includes the $\pi^0$ mass, the effective $\pi^0$-quark coupling and the pion-to-vacuum hadronic form factors, both...

Acceleration of the high energy cosmic rays protons in the active galactic nuclei is considered.

The major acceleration stage is the centrifugal acceleration in a magnetosphere of the central machine light cylinder surface. In the during to calculations, the received dependence of the maximum energy on the parameter of the magnetization $\kappa$ and relation parameter $\alpha$ of toroidal...

The experimental data obtained with Pamela, Fermi, AMS-02, spectrometers cannot be explained using the diﬀusive models of propagation of cosmic-rays accelerated at the supernova shocks and require the existence of nearby sources of cosmic rays at the distances less than one kpc. These sources could explain the growth of the ratio of galactic positrons to electrons with an increase of their...

We will present the detection of eight candidate extragalactic fast X-ray transients (+ XRT 170831 which was identified previously by Lin et al. 2019) from a parent sample of 214,701 sources in the Chandra Source Catalog Release 2.0 above $|b|{>}10^{\circ}$ (160.96 Ms over 592.4 deg$^{2}$). Our candidates have peak fluxes between 3.5$\times$10$^{-15}$ to 1.1$\times$10$^{-13}$ erg cm$^{-2}$...

The transit method is one of the most effective and reliable methods to detect the exoplanets around other stars in our galaxy. As an exoplanet passes in front of its host star along our line of sight, it causes a periodic dimming of the system’s brightness. This follows as the exoplanet blocks a portion of the host star’s radiant flux. Consequently, light curves of the system are generated,...

It is of great importance to study the properties of a proto-neutron star (PNS) because of its complex evolution into a cold NS. Under the framework of relativistic mean field theory, the repulsion and attraction between hyperons and hyperons are considered simultaneously. In addition, the hyperon-meson couplings satisfy SU(6) symmetry. By considering entropy, temperature and neutrino,...

We present X-ray spectra spanning 18 years of evolution for SN1996cr, one of the five nearest (~4 Mpc) SNe detected in the modern era. HETG observations allow us to resolve spectrally the velocity profiles of Ne, Mg, Si, S, and Fe emission lines and monitor their evolution as tracers of the ejecta-circumstellar medium (CSM) interaction. To explain the diversity of X-ray line profiles, we...

The results of 20-year observations of the Perseus cluster centering on the NGC 1275 including IC 310 radio galaxy and extragalactic supernova SN 2006gy at energies 800 GeV - 45 TeV by the SHALON telescope are presented. Also, the emission from the galactic source of nonthermal radio and X-ray emission GK Per (Nova 1901) of classical nova type was found as it accompanied to the observations....