We present the results of a search for the magnetic field inhomogeneity for the red giant ϵ Tau. This research is based on observations obtained over 10 nights in 2008–2010 with the ESPaDOnS CFHT spectropolarimeter. We found a previously undescribed instrumental effect in the ESPaDOnS spectra, consisting of random polarization outliers. Therefore, to measure the magnetic field from the unblended individual

We outline our experience in organizing the 9th edition of the International Workshop on Astronomy and Relativistic Astrophysics: from Quarks to Cosmos, in virtual format, denominated IWARA2020 Video Conference, held from 6 to 12 September, 2020. The IWARA 2020 Video Conference aimed to bring together leading academic scientists, professors, students, and research scholars for exchanging experiences

The discovery of an elite burial in Tlailotlacan, a neighborhood of Teotihuacan, gave us a unique opportunity not only to put together a group of multidisciplinary specialists, but to revive this remarkable woman who inhabited, ate, drank, and traveled through most of Mesoamerican. The different analysis carried out provided us with a unique opportunity to reconstruct part of the relations between

In this contribution, we seek to identify points of contact between the conceptions about space, time, and Cosmos, carried out by thinkers and scientists throughout history, and the corresponding cosmogonic view of the Inka culture. We conclude that a proper understanding and interpretation of the Inka legacy in the fields of astronomy and archeoastronomy can only be carried out properly when inserted

In this paper, we discuss the astronomical orientations in the city plans of Teotihuacan and Tenochtitlan. Mesoamerica exhibits much archaeoastronomy and these two sites are rich examples. Both exhibit alignments for solar horizon events that are integral in deliberate calendrical systems. The logic of these systems is shown, and this demonstrates that these cities were carefully planned with astronomical

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 (GRBs), 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

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

When minimal length uncertainty emerging from a generalized uncertainty principle (GUP) is thoughtfully implemented, it is of great interest to consider its impacts on gravitational Einstein field equations (gEFEs) and to try to assess consequential modifications in metric manifesting properties of quantum geometry due to quantum gravity. GUP takes into account the gravitational impacts on the noncommutation

We outline the modifications in the numerical Boltzmann code Cosmic Linear Anisotropy Solving System (CLASS) in order to include extra inflationary fields. The functioning of the code is first described, how and where modifications are meant to be done are later explained. In the present study, we focus on the modifications needed for the implementation of a two‐field inflationary model, with canonical

In this work, we present a brief discussion about modified and extended cosmological models using current observational tests. We show that, according to these astrophysical samples based on late universe measurements, theories like f(R) and f(T, B) can provide a useful interpretation of a dynamical dark energy. At this stage, precision cosmostatistics has also become a well‐motivated endeavor by itself

We determine the causal structure of the McVittie spacetime for a cosmological model with an asymmetric bounce. The analysis includes the computation of trapping horizons; regular, trapped, and antitrapped regions; and the integration of the trajectories of radial null geodesics before, during, and after the bounce. We find a trapped region since the beginning of the contracting phase up to shortly

We present the results of General Relativistic Magnetohydrodynamic simulations utilizing initial conditions from both the Electroweak and Quantum Chromodynamic (QCD) phase transitions in order to determine if seed magnetic fields may be generated via the Biermann Battery Mechanism of Magnetogenesis. These simulations occur in a simulated early universe between 10−11 s and 103 s after the Big Bang.

The cosmological implications of the Covariant Canonical Gauge Theory of Gravity (CCGG) are investigated. CCGG is a Palatini theory derived from first principles using the canonical transformation formalism in the covariant Hamiltonian formulation. The Einstein‐Hilbert theory is thereby extended by a quadratic Riemann‐Cartan term in the Lagrangian. Moreover, the requirement of covariant conservation

In today's scenario, going beyond Einstein's theory of gravity leads us to some more complete and modified gravity theories. One of them is the f(R, T) gravity in which R is the Ricci scalar, and T is the trace of the energy‐momentum tensor. Using a well‐motivated linear f(R, T) gravity model with a single parameter, we studied the strong energy condition (SEC), the weak energy condition (WEC), the

There exist gravitational memory effects in Brans‐Dicke theory. They are closely related to the Bondi‐Metzner‐Sachs symmetries present on the null infinity in an isolated system. By studying the asymptotically flat spacetime in Brans‐Dicke theory and the asymptotic symmetries, one discovers that the displacement memory effect in the tensor sector is due to the vacuum transition caused by the null energy

The present study reports a reconstruction scheme for f(T) gravity under the assumption that the density due to the torsion T evolves like the variable‐generalized Chaplygin gas (VGCG), a phenomenological candidate of dark energy. This reconstruction has been demonstrated in viscous as well as non‐viscous cases. The state‐finder trajectory {r − s} has been found to attain the ΛCDM fixed point under

We study the magnetic properties of a relativistic neutral vector bosons gas under the action of a constant and uniform magnetic field. An analytical expression for the magnetization at any temperature is obtained, and a discussion of the influence of the antiparticles, the vacuum, and the Bose‐Einstein condensation over this magnitude is presented. We analyze the validity of the non‐relativistic and

In 2015, the first direct detection of gravitational waves was reported. Data analysis indicated that the waves had originated from the violent collision of two black holes, which scattered them through space–time as Einstein predicted. That detection was made possible by many advances in measurement technology, mainly vibration isolation of the detector optics, since, at 10 Hz, the motion of the

In this work, a methodology to design two‐mode mechanical transducers for the spherical resonant‐mass gravitational wave detector SCHENBERG is presented. This detector uses microwave multiparametric sensors and has 17 mechanical modes together with 6 electromagnetic modes for the microwave cavities. These transducers, when placed on the spherical surface of the detector, must have an effective mass

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. We will consider both weak

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). The path, on how to determine the axial modes, serve as a starting point for more general extensions of GR, involving additions of r‐dependent functions to g00.

Surveys have shown radio‐loud (RL) quasars constitute 10–15% of the total quasar population. However, it is unknown if the radio‐loud fraction (RL quasars/Total quasars) remains consistent among different parameter spaces. This study shows that radio‐loud fraction increases for increasing full width half maximum (FWHM) velocity of the Hβ and MgII broad emission line. Our data have been obtained from

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, flat‐spectrum radio quasars (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

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 the environment‐galaxy relation is established, we study protoclusters, which are numerically dense environments of galaxies in the early Universe, and which give rise to galaxy clusters today. In this work, we use submillimeter galaxies

The stellar Initial Mass Function (IMF) seems to be close to universal in the local star‐forming regions. However, this quantity of a newborn stellar population responds differently at gas metallicities Z ∼ Z⊙ than Z = 0. A view on the cosmic star formation history suggests that the cooling agents in the gas vary both in their types and molecular abundances. For instance, in the primordial gas environment

To investigate the effect of feedback from active galactic nuclei (AGN) on their surrounding medium, we study the diffuse X‐ray emission from galaxy groups and clusters by coupling the Astrophysical Plasma Emission Code (APEC) with the cosmological hydrodynamic simulation involving AGN feedback. We construct a statistical sample of synthetic Chandra X‐ray photon maps to observationally characterize

We present a new approach to improve the forward modeling of reconstruction method for the Baryonic Acoustic Oscillations study. We use probability information from the Halo Occupation Distribution (HOD) function of a given type of galaxies in order to enhance the estimation of the local density field of the dark matter. We couple the HOD information to the Conditional Luminosity Function of red type

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 to 45 TeV by the SHALON telescope are presented. Also, the emission from the galactic source of non‐thermal radio and X‐ray emission GK Per (Nova 1901) of classical nova type was found as it accompanied to the observations. For

The process of stationary acceleration of protons by an electric field in the electromagnetic field of active galactic nuclei, including the regions of the magnetosphere of a supermassive black hole and a relativistic jet, is considered. The process of collisionless acceleration of the proton as a component of ultrahigh‐energy cosmic rays is assumed. It is shown that during acceleration to the maximum

Infrared luminous galaxies are rare locally but dominate the star formation activity at z ≥ 1. The study of these objects is difficult at optical wavelengths especially on account of the abundant dust. At the smallest scales, dust becomes micron‐sized molecules known as PAHs that are excited by UV photons and whose emission can be used to reveal physical properties of obscured regions that otherwise

In this work, we construct a sample of black hole X‐ray binaries (BH XRBs), low‐luminosity active galactic nuclei (LLAGNs), and FR Is with wider distribution of Eddington ratios and re‐explore their fundamental plane of BH activities, that is, . We find that the quiescent BH sources follow a similar fundamental plane (ξX ∼ 0.6) with sub‐Eddington BH sources very well, while the strong radio sources

We derive closed formulas for the mass M and spin a parameters of a Kerr black hole in terms of a minimal quantity of observational data: the red‐/blue‐shifts of photons emitted by massive particles (stars) moving on geodesics around the black hole and their respective orbital radius. It turns out that for a single star orbiting the black hole, we need a minimal set of four observational measurements

In spite of its key role in compact star physics, the surface tension of quark matter is not well comprehended yet. In this work, we analyze the behavior of the surface tension of three‐flavor quark matter in the outer and inner core of cold deleptonized magnetars, proto magnetars born in core collapse supernovae, and hot magnetars produced in binary neutron stars mergers. We explore the role of temperature

We study the neutrino chirality flip during the birth of a neutron star, produced in a core made of strange quark matter. This mechanism is applied to the neutron star kick velocity problem and we show that it is efficient when the neutrino magnetic moment is not smaller than 4.7 × 10−15μB, where μB is the Bohr magneton. When this lower bound is combined with the most stringent upper bound, our results

The role of magnetic field decay in normal radio pulsars is still debated. In this paper, we present results which demonstrate that an episode of magnetic field decay in hot young neutron stars can explain anomalous values of braking indices recently measured for more than a dozen of sources. It is enough to have few tens of per cent of such hot neutron stars in the total population to explain observables

Pulsars are stars whose electromagnetic radiation is observed to pulsate in well‐defined time intervals while they rotate as long as the electromagnetic signal is not emitted in the direction of the rotation axis. The frequencies of the pulses decay with time as quantified by the braking index (n). In the canonical model, n = 3 for all pulsars, but observational data yield n < 3. In this work, this

With the first multi‐messenger observation of a binary neutron star merger (GW170817), new constraints became available for masses and radii of neutron stars. We introduce a class of hybrid EoS that fulfills all these constraints and predicts a region in the mass‐radius diagram that could be populated only by hybrid neutron stars with quark matter cores. A confirmation of this conjecture would be provided

Transition of a compact star into the third family for an equation of state (EoS) featuring mass twins is considered. The energy released at a baryon number conserving the transition of static compact stars configurations is computed for two sets of models for comparison. The EoS of choice is the density‐dependent functional DD2 EoS with excluded model corrections for hadronic matter, which suffers

The stability of the recently proposed static solutions for boson stars is analyzed. These solutions of Einstein‐Klein‐Gordon (EKG) equations are obtained by considering the interaction of a real scalar field with matter. We assume that the inclusion of the scalar field in addition to matter allows one to justify that stability implies that the total mass of the solution should grow when the initial

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. 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 formation. I will also explain

In this paper, we attribute high braking indices n > 3 of two magnetars SGR 0501+4516 and 1E 2259+586 to the decrease in their inclination angles using the double magnetic‐dipole model proposed by Hamil et al. (2016). In this model, there are two magnetic moments inside a neutron star—one is generated by the rotation effect of a charged sphere, M1, and the other is generated by the magnetization of

Pulsars emit pulsed radiation at 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 calculation

In this work, we calculated the toroidal magnetic field decay rates and magnetic energy decay rates by considering the general relativity effect of AXP 1E2259 + 586 associated with the supernova remnant CTB 109. The results confirmed that the high thermal radiation on the surface of the star could be attributed to Joule heating caused by the dissipation of crustal magnetic field. We also investigated

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 particular distribution function entering the mass function m(r). The non‐singular character of the metric is warranted by the coupling of general

The equation of state provided by effective models of strongly interacting matter should comply with the restrictions imposed by current astrophysical observations on compact stars. Using the equation of state given by the (axial‐)vector meson extended linear sigma model, we determine the mass–radius relation and study whether these restrictions are satisfied under the assumption that most of the star

In high‐energy astrophysics scenarios such as Blazars, gamma‐ray bursts, or pulsar wind nebulae, it is highly probable that ultrarelativistic particles interact with photons in their environment through scattering. As long as the energy of the particle is greater than the energy of the interacting photon, the (classical) scattering is known to be in the Thomson regime. Otherwise, quantum effects will

The stability of the integrated profile of PSR B0329 + 54 at 1,540 MHz is studied with the observation data of the Nanshan 25‐m radio telescope of up to 453 hr from 2003 to 2009. We find that the profiles of two modes tend to stabilize at a faster rate first, then change to a slower rate, and then become rapidly stabilized again. It is also shown that there are distinct differences in the profile stability

In this paper, by using a perturbation theory, we evaluate the scattering solution to Schrödinger equation under the Newtonian gravitational potential. We find that the scattering amplitude f(θ) depends on the potential U, which is composed of the external part Uex and the internal part Uin, respectively. The above results are related to the mass density of a rotating Maclaurin spheroid. In the future

We present in this talk an overview of the neutron star origin events and masses. Using the existing sample of ∼80 measured neutron star masses, we show that the distribution requires more than one mass‐scale and that its highest value inferred from the sample is compatible with 2.5M⊙, suggesting that very heavy neutron stars may be present in Nature. The case of some “spider” systems and the enigmatic

In Einstein's general relativity (GR), gravity is described by a massless spin‐2 metric field, and the extension of GR to include a mass term for the graviton has profound implication for gravitation and cosmology. Besides the gravity experiments carried out in the Solar System and those recently with gravitational waves (GWs), pulsar timing observations provide a complementary means to test the masslessness

The detection of event GW170817 and its electromagnetic counterpart started the era of multi‐messenger astronomy with gravitational waves. The observational constraints from this event and the estimation of mass and radius of PSR J0030 + 0451 is being used to get insights related to the nature of matter inside these compact objects. In this work, we construct hybrid equations of state using modern

Compact stars consisting of strange quark matter and strange matter with admissible dark matter are studied by solving the Tolman‐Oppenheimer‐Volkoff equations for two fluids interacting only by gravity, with the dark‐matter EoS obtained by means of galaxy rotation curves. The properties of these stars are explored by means of the modeling of their mass‐radius relations and gravitational redshifts

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 from the accretion disk is occurring. The region where this process takes place, called the corona, is characterized by only two parameters: its thermal energy kT and its optical depth τ. Hard X‐ray spectra analysis is, thus, an imperative tool in diagnosing

What if normal baryonic matter is compressed so tightly that atomic nuclei come into close contact? This question has been asked since 1930s. The first answer was presented by Lev Landau whose speculation has been developed, and the concept of neutron star is then popularized. However, another answer is related to strange star, which becomes worthy of attention especially after the establishment of

The macroscopic structure of magnetized Compact Objects is deformed due to the anisotropy of pressures as a consequence of the magnetic field. In this work, we study the impact of the magnetic deformation in the moment of inertia and mass quadrupole moment of strange stars. In order to do that, we first solve the structure equations using the gamma metric: an axially symmetric metric in spherical coordinates

We present a modeling of the thermal evolution of the neutron stars, incorporating an effect of neutron and proton pairing. The considered equation of state with induced surface tension (IST) reproduces properties of normal nuclear matter, fulfills the proton flow constraint, provides a high‐quality description of particle yields created in heavy‐ion collisions, and is equally compatible with the constraints

Cygnus X‐3 (Cyg X‐3) is the famous binary system containing a black hole. It is actively studied through the wide range of electromagnetic spectra from radio band up to ultrahigh energies. Cyg X‐3 has long been considered 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 to 100 TeV with the SHALON telescope

The experimental data obtained with Pamela, Fermi, AMS‐02, and other 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 1 kpc. These sources could explain the growth of the ratio of galactic positrons to electrons with an increase of their

In this work, we investigate how the assumption of chemical equilibrium with leptons affects the deconfinement phase transition to quark matter. This is carried out within the framework of the Chiral Mean Field model allowing for nonzero net strangeness, corresponding to the conditions found in astrophysical scenarios. We build three‐dimensional quantum chromodynamics phase diagrams with temperature

An analysis of accelerated kaon decays based on the Unruh effect shows a slight decrease in a CP violation parameter for very high accelerations as a consequence of the previously known increase in decay rates for noninertial systems. Its consequences regarding the understanding of the relation between thermal and noninertial phenomena are briefly discussed.