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Remo Ruffini (ICRANet)19/06/2023, 09:00
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Dong-Hoon Kim (Seoul National University)19/06/2023, 09:45
We consider a situation in which a quasar contains a source of gravitational waves (e.g. binary black holes) and electromagnetic waves from the quasar interact with gravitational waves from the source. The effect will be appreciable if the interaction initially takes place close to the source of gravitational waves where the strain amplitude can be large. This situation can be modeled...
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Carlo Luciano Bianco (ICRANet)19/06/2023, 11:00
Due to the technical time delay of the XRT instrument on board the Neil Gehrels Swift Observatory satellite, we cannot observe the X-ray emission occurring less than ∼40 s after a gamma-ray burst (GRB) trigger time. We here indicate a new strategy of using the cosmological time dilatation in high redshift GRBs to observe the earliest X-ray emission by Swift/XRT in the GRB cosmological...
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Wonwoo Lee19/06/2023, 16:00
We report the charged rotating black hole with an additional matter field. The geometry is obtained by adopting the Newman-Janis algorithm, and the solution of Maxwell fields is also obtained by that. We discuss the properties of that rotating black hole with the energetics, black hole shadow, and others.
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Mr Shurui Zhang (ICRANet & USTC)19/06/2023, 16:45
We analyze the “ballistic method” of rotational energy extraction from an (extreme) Kerr black hole (BH) by massive particle decay in the BH ergosphere pioneered by Roger Penrose. We focus on the negative energy counterrotating particles in-going to the horizon and evaluate the feedback on the BH irreducible mass (∆Mirr > |E1|). The change in irreducible mass is a function of the ratio of the...
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Sang Pyo Kim (Kunsan National University)20/06/2023, 09:00
Charged black holes have been proposed as a central engine for GRBs.Damour and Ruffini proposed Schwinger mechanism of KN black holes as the central engine [Phys. Rev. Lett. 35, 332 (1975)] while Blandford and Znajek proposed that the magnetic fields surrounding rotating black holes supported by current of disks induce strong electric fields to produce electron-positron pairs for GRBs [Mon....
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Gregory Vereshchagin (ICRANet)20/06/2023, 09:45
We consider pair production in uniform electric field in presence of electron-positron plasma. Depending on initial pair distirbution in momentum space pairs are either created or annihilated in external field. Pair are either created or annihilated depending on their initial distribution. We show that electric field cannot be enhanced by inverse Schwinger process.
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Gregory Vereshchagin (ICRANet)20/06/2023, 10:05
We determine multipole coefficients of electromagnetic field for charged particle, radially falling into Schwarzschild black hole by approximating the Regge-Wheeler potential by the Dirac delta-function. Considering the limit when the particle is approaching the event horizon of the black hole we show analytically that all multipoles except for the monopole vanish exponentially fast.
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Massimo Della Valle20/06/2023, 11:00
Optical surveys have been proven inefficient in detecting Supernovae events in our galaxy. In the face of 7 expected core-collapse SNe in the last 4 centuries, zero SNe have actually been observed. Present and future neutrino telescopes such as Super-Kam or Hyper-Kam have the capabilities to observe large numbers of neutrinos from SNe occurring ìnside the Milky Way and Local Group of Galaxies,...
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Chan Park (Institute for Basic Science)20/06/2023, 16:00
Gravitational wave (GW) detection using electromagnetic (EM) cavities has garnered significant attention in recent years. With ongoing experiments on axion detection using highly sensitive electromagnetic cavity, there is potential to apply these existing facilities to GW detection, opening up a new channel of GW observation. In this review, we comprehensively examine the principles of GW...
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Jorge Armando Rueda Hernandez (ICRANet)20/06/2023, 16:45
The binary-driven hypernova (BdHN) model explains long GRBs associated with type Ic supernovae (SNe) with a binary composed of a carbon-oxygen (CO) star and a neutron star (NS) companion in close orbit. The CO core-collapse SN generates a newborn NS (new-NS) at its center and ejects the CO outer layers. This process triggers the GRB, starting from the accretion of ejecta onto the new-NS (via...
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Prof. Stefano Scopel (Sogang University)21/06/2023, 09:00
Weakly interacting massive particles (WIMPs) can be captured in compact stars such as white dwarves (WDs) if they are in a dark matter-rich environment, leading to an increase in the star luminosity through their annihilation process. I will show that if the WIMP interacts with nuclear targets through inelastic scattering the data on low-temperature large-mass WDs in the Messier 4 globular...
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Lorenzo Amati (INAF - OAS Bologna)21/06/2023, 09:45
The huge luminosity, the redshift distribution extending at least up to z∼10 and the association with the explosive death of very massive stars make long GRBs (i.e., those lasting up to a few minutes) potentially extremely powerful probes for shedding light on main open issues in our understanding of the early Universe: star formation rate evolution up to the first generation of stars...
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Jorge Armando Rueda Hernandez (ICRANet)21/06/2023, 11:00
The binary-driven hypernova (BdHN) model explains long GRBs associated with type Ic supernovae (SNe) with a binary composed of a carbon-oxygen (CO) star and a neutron star (NS) companion in close orbit. The CO core-collapse SN generates a newborn NS (new-NS) at its center and ejects the CO outer layers. This process triggers the GRB, starting from the accretion of ejecta onto the new-NS (via...
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Rahim Moradi (ICRANet and ICRA-Sapienza)21/06/2023, 11:45
We propose that the progenitor of the Crab Nebula and the Crab pulsar shares similarities with binary-driven hypernovae. The understanding of binary-driven hypernovae has revealed the crucial role played by the explosion of the supernova, as well as the hypercritical accretion of the supernova ejecta onto the binary companion neutron star (NS) and the newborn NS (νNS) in determining the...
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Dong-hun Lee22/06/2023, 09:00
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Yu Wang (ICRANet, INAF)22/06/2023, 09:45
I will provide two examples of machine learning applications in astrophysics. The first example is using deep neural networks to test the unification model of active galactic nucleus (AGN). The second example is a comparison between a simple specific neural network and a Fine-Tuned GPT model for the estimation of spectral redshift.
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Antonio Enea Romano (UDEA/CERN)22/06/2023, 11:00
Using conformal invariance of gravitational waves, we show that for a luminal modified gravity theory, the gravitational-wave propagation and luminosity distance are the same as in general relativity. The relation between the gravitational-wave and electromagnetic-wave luminosity distance gets however modified for electromagnetism minimally coupled to the Jordan frame metric. Using effective...
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Bum-Hoon Lee22/06/2023, 16:00
Recent precise measurements suggest the needs beyond the standard lambda CDM cosmological model. We specifically consider gravity with the additional Gauss-Bonnet higher curvature term and study some astrophysical and cosmological implications.
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Jose Fernando Rodriguez Ruiz (Universidad Industrial de Santander)22/06/2023, 16:45
Semi-analytical models of gravitational wave (GW) radiation are constructed following first principles. They are more than mere academic exercises and can be used to compute qualitative and quantitative results. We study a semi-analytical approach to gravitational radiation from rotating ellipsoids (Riemann ellipsoids), whose internal matter is described by a polytropic equation of state. It...
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Chanyong Park23/06/2023, 09:00
We study the time evolution of entanglement entropy in expanding universes with various matters. To describe expanding universes holographically, we take into account a braneworld moving in an asymptotic AdS space involving a uniform p-brane gas. In the braneworld model, an observer living in the braneworld detects the bulk motion of the braneworld as an expanding universe. We show that the...
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Remo Ruffini (ICRANet, ICRA, INAF)23/06/2023, 09:45
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Prof. Muhammad Sharif23/06/2023, 11:00
In this paper, we consider a non-static spherical geometry and formulate its extension for the case of anisotropic matter configuration through minimal gravitational decoupling in curvature-matter coupled gravity. We apply a particular transformation only on the radial metric function that divides the modified field equations into two distinct sectors corresponding to their parent (original...
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Abdel Nasser Tawfik (Egyptian Center for Theoretical Physics, Future University in Egypt)23/06/2023, 11:20
To reconcile principles of general relativity (GR) and quantum mechanics (QM), differential and quantum geometry, duality-symmetry configurations of distance and momentum, the Born reciprocity principle (BRP), and noncommutative algebra, especially the relativistic generalized uncertainty principle (RGUP), are simultaneously applied on GR and QM. The latter integrates gravitational fields in...
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Sung-Won Kim23/06/2023, 16:00
We consider a binary system consisting of two traversable wormholes as one of the gravitational wave source candidates. If the two wormholes are far enough apart from each other, they can be treated as point masses, and the properties of gravitational waves generated by the system is very similar to those of a binary compact star system. However, when they approach each other and the system is...
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She-Sheng Xue (ICRANet, Physics Department, Sapienza University of Rome)23/06/2023, 16:45
We study the classical Friedman equations for the time-varying cosmological term $\tilde\Lambda$
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and Hubble function $H$, together with quantised field equations for the production of massive $M\gg H$ particles, namely, the $\tilde\Lambda$CDM scenario of dark energy and matter interactions. Classical slow components ${\mathcal O}(H^{-1})$ are separated from quantum fast components ${\mathcal... -
Abdel Nasser Tawfik (Egyptian Center for Theoretical Physics)
General theory and quantum mechanics are fundamentally very different theories with distinct formulations. Nevertheless, both of them claim to predict how Nature works! The everlasting battle for exploring and understanding the Universe and for privileging a consistent perception of reality is therefore awaiting a consolidator rather than a conqueror. This should be capable of either unifying...
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