-
Marta Burgay (INAF - Osservatorio Astronomico di Cagliari)
Pulsars are extremely stable natural clocks and, when found in relativistic binary systems, they can be used as exceptional laboratories to test Relativistic gravity in the strong field regime. In this talk I will present the results obtained in this context by studying the now 20-year-long dataset on the double pulsar system J0737-3039A/B, the only binary hosting two active radio pulsars, and...
Go to contribution page -
Baptiste Sirvente, Jorge Armando Rueda Hernandez (ICRANet)
We present a general relativistic framework to calculate the rate at which a compact star accretes dark matter particles from its environment. We apply the framework to a realistic neutron star in a fermionic dark matter halo. We discuss the effect of accreted dark matter on the interior structure and stability of the neutron star and outline astrophysical consequences, extensions, and...
Go to contribution page -
Zenia Zuraiq (Indian Institute of Science, Bangalore)
Neutron stars, at their cores, are highly dense and, thus, are expected to have a number of exotic processes. This includes a possible phase transition to deconfined quark matter at the core, leading to a hybrid star. The quark matter is expected to additionally be color superconducting. The physics of superconductivity plays an important role in understanding the high density matter in the...
Go to contribution page -
Shurui Zhang (ICRANet)
We report on the increase in irreducible mass resulting from a particle’s plunge along the inner most stable circular orbit (ISCO) into a black hole (BH), examining both cases: the conservative approximation and with gravitational wave (GW) radiation; the former corresponds to BH accretion, and the latter to extreme mass-ratio inspirals (EMRIs). For prograde orbits, we find that the ratio of...
Go to contribution page -
Dr Bobir Toshmatov (New Uzbekistan University)
We demonstrate how the shadow radius of regular black holes can serve as a powerful diagnostic tool for general relativity coupled with nonlinear electrodynamics (NED). By analyzing Bardeen-like, Hayward-like, and Maxwellian regular spacetimes, we highlight the critical distinction between standard null geodesics and the NED-driven effective photonsphere that governs light propagation. We show...
Go to contribution page -
Jutta Kunz (University of Oldenburg)
Black holes, with their strong gravitational fields, provide an important testing ground for theories of gravity beyond General Relativity. Among the many proposed alternatives, considerable recent work has focused on scalar-tensor theories in which a scalar field couples to higher-curvature terms. The black hole solutions that arise in such theories can differ significantly from the...
Go to contribution page -
Felix Mirabel (Instituto de Astronomia y Fisica Espacial. Universidad de Buenos Aires)
The radio emission from Microquasars (MQs), Little Red Dots (LRDs) and Active Galactic Nuclei (AGN) is crucial to gain insight into the mass accretion, relativistic jets and feedback of black holes (BHs) in these astronomical objects. Based on archived radio monitoring data and the VLASS and FIRST sky surveys of the National Radio Observatory (NRAO), were obtain the following achievements: (1)...
Go to contribution page -
Wentao Luo (USTC)
This work presents, for the first time, direct constraints on the black hole─halo mass relation using weak gravitational-lensing measurements. We construct type I and type II active galactic nucleus (AGN) samples from the Sloan Digital Sky Survey, with a mean redshift of 0.4 (0.1) for type I (type II) AGNs. This sample is cross correlated with weak-lensing shear from the Ultraviolet Near...
Go to contribution page -
Carlos Raúl Argüelles (Universidad Nacional de La Plata)
The study of disc accretion physics around supermassive black hole (BH) candidates provides essential theoretical tools to test their nature. In this talk I present recent results about the accretion flow and associated emission using generalised α-discs accreting onto horizonless dark compact objects, and compare with the traditional BH scenario. The BH alternative consists in a dense and...
Go to contribution page -
GeonWoo Kang (Seoul National University)
We present a powerful new diagnostics by which the running of scalar spectral index of primordial density fluctuations can be tightly and independently constrained. This new diagnostics utilizes coherent rotation of void galaxies, which can be observed as redshift asymmetry in opposite sides dichotomized by the projected spin axes of hosting voids. Comparing the numerical results from the...
Go to contribution page -
Gregory Vereshchagin (ICRANet)
Cooling of newborn quark stars occurs through neutrino emission from their interiors and photon and electron-positron pairs emission from their surface. We will discuss the cooling process of bare hot quark stars with particular emphasis on luminosity and spectrum, providing input for ongoing observational programs in X-rays.
Go to contribution page -
Eugene Oks (Auburn University, USA)
The explanation of a puzzling observation by Bowman et al 2018 (Nature, 555, 67) of the redshifted 21 cm spectral line from the early Universe, where it was found that the absorption in this line was about 2 to 3 times stronger than predicted by the standard cosmology and thus the primordial hydrogen gas was significantly cooler than predicted by the standard cosmology, required as the cooling...
Go to contribution page -
Jorge Armando Rueda Hernandez (ICRANet)
We discuss alternative astrophysical probes of dark matter by estimating its effects on the dynamics and structure of compact objects, such as white dwarfs, neutron stars, and black holes. We analyze gravitational dynamical friction on compact-object binaries, dark-matter accretion, and tidal disruption, and how these effects constrain the nature of the dark-matter particle in observed...
Go to contribution page -
Manuel Hohmann (University of Tartu)
One of the most important open questions in cosmology is the so-called Hubble tension, which is an apparent disagreement between local universe measurements of the present-time Hubble parameter and measurements inferred from early-universe observations under the assumption of the $\Lambda$CDM model, which supplements general relativity (GR) with a cosmological constant $\Lambda$ and cold dark...
Go to contribution page -
Stanislav Komarov (Belarusian State University)
The charged axially-symmetric conductor with charge in the vicinity of Kerr black hole is considered. The electromagnetic field of this conductor in the form of multipole expansion is calculated by using the Teukolsky equation. The structure of electric and magnetic field lines is analyzed. The case when conductor is located almost at the event horizon is considered. The astrophysical...
Go to contribution page -
Noraiz Tahir (Department of Physics and Astronomy, School of Natural Sciences (SNS), National University of Science and Technology (NUST), H12, Islamabad, Pakistan)
It had been proposed [Qadir A., Tahir N., and Sakhi M., PRD 100, (2019)] that virial clouds “propped up” by the cosmic microwave background (CMB), and hence at that temperature, populate dark matter halos and may account for a significant fraction of the missing baryons. To understand the nature of these clouds, it is necessary to trace their evolution from the last scattering surface (LSS)...
Go to contribution page -
Jaan Einasto (Prof.)
I provide a review of the fractal properties of the cosmic web. Extreme views on fractal properties were expressed by Pietronero and Davis. To get an unbiased view on fractal properties I describe fractal function found from angular 2D and spatial 3D distributions of galaxies, using numerical simulations and SDSS samples of galaxies in a box of side length 512 Mpc/h. To measure the fractal...
Go to contribution page -
Prof. Nigel Bishop (Rhodes University)
The interaction of gravitational waves (GWs) passing through matter is normally treated as being very weak. We have re-investigated this issue using linearized perturbations within the Bondi-Sachs formalism, with a model comprising a spherical shell of matter surrounding a GW source. We find analytic expressions for the GWs when the background is Minkowskian, but for a general spherically...
Go to contribution page -
Dr Yerlan Aimuratov (Fesenkov Astrophysical Institute)
Observations of supernovae (SNe) Ic occurring after the prompt emission of long gamma-ray bursts (GRBs) are addressed within the binary-driven hypernova (BdHN) model, where GRBs originate from a binary composed of 10 solar masses carbon–oxygen (CO) star and a neutron star (NS). We report on recent progress in understanding the phenomenon and draw some prospects on GRB-SN research.
Go to contribution page -
Prof. Oleg Zaslavskii (Kharkov V. N. Karazin National University)
During last decade and a half many results are obtained that show when (i) particle collisions in a strong gravitational eld lead to an unbounded energy in the center of mass Ec:m: of two colliding particles, (ii) when the process leads also to signi cant energy extraction measured at in nity. The set of possible scenarios can be divided to three main cases: (i) collisions near black holes,...
Go to contribution page -
Prof. Banibrata Mukhopadhyay (Indian Institute of Science)
Over the last one and half decades, along with my group members and collaborators, I have been exploring the possible existence of (highly) magnetized white dwarfs exceeding the Chandrasekhar limit. This helps understanding perculiar over-luminous type Ia supernovae which predict their progenitor mass well above 1.4 solar mass Chandrasekhar limit. By theory, numerical calculations and...
Go to contribution page -
Roland Diehl (Max Planck Institut fuer extraterrestrische Physik and TU Munich, Garching, Germany)
Characteristic gamma-ray lines can be measured from nuclear processes and from positron annihilations in cosmic sites. Nuclear transitions may originate from radioactive by-products of nucleosynthesis, or from energetic collisions at MeV to GeV energies. Positrons may originate from pair production in strong fields or from nuclear decays. Both the nuclear decays and the annihilations of...
Go to contribution page -
Federico Lelli (INAF - Arcetri Astrophysical Observatory)
Milgromian dynamics (or Modified Newtonian Dynamics, MOND) is a major alternative to particle dark matter proposed in 1983 by Mordehai Milgrom. MOND modifies the non-relativistic laws of gravity and/or inertia at low accelerations, below a characteristic acceleration scale a0. In this invited talk, I will showcase the content of the first "MOND white paper" which results from the collaboration...
Go to contribution page -
Gennady Bisnovatyi-Kogan (Space Research Institute Rus. Acad. Sci., Moscow, Russia)
Models of neutron and strange stars are studied within the approximation of a uniform density distribution. A universal algebraic equation, valid for any equation of state, is used to estimate the stellar mass at a given density without resorting to the numerical integration of differential equations. Different equations of state for neutron stars had been used.
Go to contribution page
Homogeneous strange star... -
Dr Reinoud Slagter (ASFYON, Astronomisch Fysisch Onderzoek Nederland)
It is believed that black holes remain a clean laboratoryfor probing ideas about quantum gravity. Decades of work on these obscure objects have shown they behave could behave like ordinary thermodynamic systems with temperature and entropy, or to the extreme, even as elementary particles.
Go to contribution page
It remains a huge challenge to reconcile the large-scale properties with the underlying quantum... -
Dr Igor Kanatchikov (Natl. Quantum Information Center in Gdansk)
We show that a variety of non-Keplerian galaxy rotation curves, together with the corresponding modifications of the Newtonian potential and dynamics, including MOND, qMOND, and mMOND-type behaviors, can be derived for test particles propagating on a background quantum geometry associated with a quantum spin connection, as described by precanonical quantum gravity (pQG).
In particular, we...
Go to contribution page -
Yuanbin Wu (Nankai University)
Owing to the capability of providing extreme conditions such as extremely intense electromagnetic files and high-energy-density environments in the laboratory, high-power laser facilities offer powerful platforms for the studies of various research fields such as particle physics, nuclear physics, and astrophysics. In this talk, we will present and discuss our recent progresses on the studies...
Go to contribution page -
Kirill Zhirkov (Lomonosov Moscow State University)
In 2013, neutrino observatory IceCube first reported discovery of high-energy (100 TeV and more) neutrinos of astrophysical origin. However, due to a bad spatial localization of these neutrinos (more than 1 arcdegree) origin of these neutrinoes stayed unknown. To find their progenitor, IceCube Collaboration organized multimessenger observations. Since 2016, IceCube Collaboration has published...
Go to contribution page -
Prof. She-Sheng Xue (ICRANet, Physics Department, Sapienza University of Rome)
Wheeler's spacetime foams (wormholes) at the Planck length undergo quantum nucleation, oscillation and annihilation. Their collective excitations over foamy spacetime interact with field operators at large distances. We describe such collective excitation and interaction using an effective ``foamon'' field coupled with field operators. The Wilson renormalisation group approach shows that the...
Go to contribution page -
Prof. Marat Gilfanov (MPA, Garching & IKI, Moscow)
After more than two years of scanning the sky during 2019--2022 the eROSITA X-ray telescope aboard SRG orbital observatory produced the best ever X-ray maps of the sky and discovered more than three million X-ray sources, of which about 20\% are stars with active coronas in the Milky Way, and most of the rest are galaxies with active nuclei, quasars and clusters of galaxies. eROSITA detected...
Go to contribution page -
Paul Frampton (UniSalento)
We discuss an electromagnetic theory for accelerated cosmic expansion which predicts charged Reissner-Nordstrom objects named astrons. In the theory electromagnetism dominates gravitation at the largest cosmological scales, over 100Mpc, just like inside an atom. If there is time, we shall discuss a possible astron explanation for the Hubble tension and briefly discuss possible detection of astrons.
Go to contribution page -
Dr Kirsten Hall (Center for Astrophysics | Harvard & Smithsonian)
Despite recent discoveries of quasar feedback in action through outflows and jets, the amount of energy that the active nucleus is capable of injecting into the extended medium of the host galaxy remains unknown. Theory suggests that quasar winds produce very hot gas bubbles that extend through the host galaxy and into the circumgalactic medium. Because this gas component is so hot and...
Go to contribution page -
Patricio Gallardo (University of Pennsylvania)
The inverse-square law of gravitation has been tested from microscopic to solar system scales. However, directly probing gravity at galactic and cosmological scales remains a challenge. At galactic scales, the missing mass dominates rotation curves, while extragalactic tests often depend on the assumed expansion history of the universe. These dependencies complicate model-agnostic tests of...
Go to contribution page -
Fernando Izaurieta (Universidad San Sebastián)
A single geometric invariant fixes the relative normalization and structure of gravity, Yang-Mills theory, and fermion kinetic terms, including ghost freedom in the gravitational sector, without tuning. Our results establish a minimal geometric route to unification that does not rely on extra dimensions or symmetry breaking by hand. Unlike previous gauge-gravity constructions, the relative...
Go to contribution page -
Prof. Sergey Bulanov (ELI-ERIC, ELI BEAMLINES, Za Radnicí 835, Dolní Břežany, 25241, Czech Republic)
Reaching and exceeding the critical quantum electrodynamics (QED) field strength—the Schwinger limit—remains a central open challenge in modern physics. In this regime, the vacuum becomes unstable with respect to electron–positron pair production, marking the onset of nonperturbative strong-field phenomena. Access to such conditions would establish a qualitatively new domain of laboratory...
Go to contribution page -
Asghar Qadir (None)
A modification of the Einstein-Hilbert Lagrangian by introducing an explicit coupling between the gravitational field, given by the Weyl tensor, and the matter-energy content, given by the stress-energy tensor, was proposed to explain flat galactic rotation curves without the exotic (non-baryonic) dark matter (DM) [Qadir, A., and Lee, H.W., IJMPD, 28, 2040014, (2019)], as Modified Relativistic...
Go to contribution page
Choose timezone
Your profile timezone: