601 talks across 60 sessions. Search by title, author or full text.
601 results
al-Farabi Kazakh National University We study numerically a combined gravitational and nonlinear magnetic lensing effect on electromagnetic flux. A magnetar with a dipole magnetic field and background gravitational field is considered to deflect the light rays…
We explore the properties of photospheric emission in gamma-ray bursts (GRBs) based on relativistic hydrodynamical simulations and Monte Carlo radiation transfer calculations. Our simulations confirm that photospheric emission gives rise to correlations betwee…
In loop quantum gravity (LQG), the volume operator plays a crucial role in the study of quantum geometry and quantum dynamics. However, the effect of the volume operator is studied only for some simple cases. In this talk, we introduce a numerical algorithm th…
I will review the recent developments of GR MHD numerical simulations of GRB central engines. I will also present some multi-messenger observational challenges still unsolved by these models. Extended theories of electromagnetism and their impact on laboratory…
Remnants of binary black-hole mergers can gain significant recoil or kick velocities due to the anisotropic emission of gravitational waves, which may leave a characteristic imprint in the observed signal. So far, only one gravitational-wave event supports a n…
JWST’s discoveries of black holes with masses ∼ 108M when the Universe was less than 5% of its current age challenge our understanding of star and black hole formation. The leading hypothesis to explain these observations is the inflowing of a large amount of…
With the proliferation new and more sensitive detector technologies, coincident observation of triggers for two or more messengers (gravitational-waves, electromagnetic, neutrinos) will become increasingly frequent. I will discuss implications and unmet needs…
Most observed binary black hole (BBH) mergers belong to the stellar-mass BBH population produced by the collapse of isolated stars. A pair-instability supernova (PISN) mechanism prevents the formation of black holes from the stellar collapse with mass greater…
The deployment of large sky surveys are enabling the characterization of the transient night sky in unprecedented detail. Among other things, such surveys are revealing novel modes of variability around supermassive black holes which are incompatible with the…
The peculiar motion of an observer relative to an ideal reference frame at rest with respect to the cosmic background produces boosting effects which modify and transfer at higher multipoles the frequency spectrum of the isotropic background. To mitigate the c…
Horizonless compact objects may produce phenomenological features which distinguish them observationally from black holes. In particular, the images of the accretion disks around them possess a characteristic morphology including a series of central bright rin…
A cosmological model with a new variant of Chaplygin gas obeying an equation of state(EoS), p = −B where B = B0an [1], is investigated in the context of its thermodynamical behaviour. Here B0 and n are constants and a is scale factor. We show that the equation…
We discuss a possible electromagnetic analog of MOND by extending the recently proposed mechanism of emergence of MOND from quantum fluctuations of spin connection in precanonically quantized general relativity (arXiv:2311.05525 [gr-qc]) to a classical particl…
In this talk I will first review the late-time phenomenology required to solve the Hubble tension, making especial emphasis on the pivotal role played by the data on baryon acoustic oscillations (BAO) in the building of the inverse distance ladder. I will show…
In the binary-driven hypernova (BdHN) scenario, long gamma-ray bursts (GRBs) originate in a binary system composed of a carbon-oxygen (CO) star and a neutron star (NS) companion in close orbit. The collapse of the CO star generates a newborn NS (νNS) at its ce…
The interface between Quantum Information and Quantum Field Theory –especially Quantum Gravity – is emerging as a forefront area of fundamental physics. But there is some tension between the way the basic concepts are commonly understood by the two communities…
USJ-IRAP-ITP We investigate whether there are evidences for the existence of a new tension on the matter density parameter, independent or in relation with the Hubble or the matter fluctuation parameter tension, and that using a combination of multiple probes…
The dynamical stability of differentially rotating neutron stars is of paramount importance in understanding the fate of the post-merger remnant of binary neutron stars mergers and the formation of black holes during core collapse supernovae. We study systemat…
Double white-dwarf (DWD) mergers are relevant astrophysical sources expected to produce massive, highly-magnetized WDs, supernovae (SNe) Ia, and neutron stars (NSs). There are expected to be numerous sources in the sky, but none have been yet detected, evading…
Cosmic voids, large under-dense regions in the Universe, serve as promising laboratories for extracting cosmological information. They offer opportunities to explore deviations from ΛCDM and provide insights into dark energy and modification of gravity. Upcomi…
Recent measurements revealed the presence of several features in the cosmic ray spectrum. In particular, the proton and helium spectra exhibit a spectral hardening at ≈ 300 GV and a spectral steeping at ~ 15 TV, followed by the well known knee-like feature at…
Many stripped-envelope supernovae (SNe) present a signature of high-velocity material responsible for broad absorption lines in the observed spectrum. These include SNe associated with long gamma-ray bursts (LGRBs), low-luminosity GRBs (llGRBs), and SNe not as…
Astrometric data presented in ATNF Pulsar Catalogue have enabled us to determine the trajectories through the Galactic potential for different kick-velocity models of pulsars. The system was disrupted ~0.2-0.8 Myr ago, which must correspond to the true age of…
Astrometric data presented in ATNF Pulsar Catalogue have enabled us to determine the trajectories through the Galactic potential for different kick-velocity models of pulsars. The system was disrupted ~0.2-0.8 Myr ago, which must correspond to the true age of…
Observations and numerical simulations indicate that non-homogeneous magnetic fields are ubiquitous in astrophysical settings. However, in most models of astrophysical non-thermal radiation they are not treated as non-homogeneous. Here we present our analysis…