A5039967505- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Solar and Space Plasma Dynamics
- Laser-Plasma Interactions and Diagnostics
- Galaxies: Formation, Evolution, Phenomena
- Neutrino Physics Research
- Complex Systems and Time Series Analysis
- Nuclear physics research studies
- Astronomical Observations and Instrumentation
- Planetary Science and Exploration
- Evolutionary Game Theory and Cooperation
- Dark Matter and Cosmic Phenomena
- Methane Hydrates and Related Phenomena
- Evolution and Genetic Dynamics
- Cosmology and Gravitation Theories
- Ionosphere and magnetosphere dynamics
- Plant Water Relations and Carbon Dynamics
- Geophysics and Gravity Measurements
- Theoretical and Computational Physics
- Particle Accelerators and Free-Electron Lasers
Tel Aviv University
2015-2024
The University of Tokyo
2020
Hebrew University of Jerusalem
1999-2015
Sapienza University of Rome
2015
California Institute of Technology
2005-2010
Centre for Theoretical Physics and Astrophysics
2006
Centre National de la Recherche Scientifique
2005
Institut d'Astrophysique de Paris
2004-2005
Institute for Advanced Study
2004
Hebrew College
2002
Gravitational waves have been detected from a binary neutron star merger event, GW170817. The detection of electromagnetic radiation the same source has shown that occurred in outskirts galaxy NGC 4993, at distance 40 megaparsecs Earth. We report counterpart radio appears 16 days after allowing us to diagnose energetics and environment merger. observed emission can be explained by either collimated ultra-relativistic jet viewed off-axis, or cocoon mildly relativistic ejecta. Within 100...
Merging neutron stars offer an exquisite laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of electromagnetic counterpart EM170817 to gravitational waves (GW170817) detected from merging stars. By synthesizing a panchromatic dataset, we demonstrate that are long-sought production site forging heavy elements by r-process nucleosynthesis. The weak gamma-rays seen dissimilar classical short gamma-ray bursts with...
We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to September 2009, for total 76 GRBs, and present an additional three pre-Swift not included in earlier sample. Furthermore, we publish 840 new points 42 GRB afterglows, sets 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A 080810. analyzed light curves all derived spectral energy distributions with best quality, allowing us estimate host...
With the first direct detection of merging black holes in 2015, era gravitational wave (GW) astrophysics began. A complete picture compact object mergers, however, requires an electromagnetic (EM) counterpart. We report ultraviolet (UV) and X-ray observations by Swift Nuclear Spectroscopic Telescope ARray (NuSTAR) EM counterpart binary neutron star merger GW170817. The bright, rapidly fading emission indicates a high mass ($\approx0.03$ solar masses) wind-driven outflow with moderate...
Compact binary mergers are prime sources of gravitational waves (GWs), targeted by current and next generation detectors. The question 'what is the observable electromagnetic (EM) signature a compact merger?' an intriguing one with crucial consequences to quest for GWs. We present large set numerical simulations that focus on EM signals emerge from dynamically ejected subrelativistic material. These outflows produce time-scale day macronovae – short-lived infrared (IR) ultraviolet (UV)...
Gamma-ray bursts (GRBs) have been separated into two classes, originally along the lines of duration and spectral properties, called "short/hard" "long/soft." The latter conclusively linked to explosive deaths massive stars, while former are thought result from merger or collapse compact objects. In recent years, indications accumulating that short/hard versus long/soft division does not map directly onto what would be expected classes progenitors, leading a new classification scheme Type I...
As a long GRB jet propagates within the surrounding stellar atmosphere it creates cocoon composed of an outer Newtonian shocked material and inner (possibly relativistic) material. The deposits $10^{51}-10^{52}$ erg into this cocoon. This energy is comparable to GRB's accompanying supernova, yet its signature has been largely neglected so far. A fraction released during expansion following breakout from star later as interacts with matter. We explore here possible signatures emission outline...
The short Gamma-Ray Burst, GRB170817A, that followed the binary neutron star merger gravitational waves signal, GW170817, is not a usual sGRB. It weaker by three orders of magnitude than weakest sGRB seen before and its spectra, showing hard early signal softer thermal spectrum, unique. We show, first, $\gamma$-rays must have emerged from at least mildly relativistic outflow, implying jet was launched following merger. then show observations are consistent with predictions shock breakout:...
Short Gamma-Ray Bursts (SGRBs) are believed to arise from compact binary mergers (either neutron star-neutron star or black hole-neutron star). If so their jets must penetrate outflows that ejected during the merger. As a jet crosses ejecta it dissipates its energy, producing hot cocoon which surrounds it. We present here 3D numerical simulations of propagation in mergers' and we calculate resulting emission. This emission consists two components: cooling emission, leakage thermal energy...
The first light from a supernova (SN) emerges once the SN shock breaks out of stellar surface. light, typically UV or X-ray flash, is followed by broken power-law decay luminosity generated radiation that leaks expanding gas sphere. Motivated recent detection emission very early stages several SNe, we revisit theory breakout and following emission, paying special attention to photon–gas coupling deviations thermal equilibrium. We derive simple analytic curves SNe various progenitors at...
We present detailed optical, X-ray and radio observations of the bright afterglow short gamma-ray burst 051221a obtained with Gemini, Swift/XRT, Very Large Array, as well optical spectra from which we measure redshift burst, z=0.5464. At this isotropic-equivalent prompt energy release was about 1.5 x 10^51 erg, using standard synchrotron model find that blastwave kinetic is similar, E_K,iso ~ 8.4 erg. An observed jet break at t 5 days indicates opening angle 7 degrees total beaming-corrected...
The light from a shock breakout of stellar explosions, which carries wealth information, strongly depends on the velocity at time breakout. emission Newtonian breakouts, typical in regular core-collapse supernovae (SNe), has been explored extensively. However, large variety explosions result mildly or ultrarelativistic where observed signature is unknown. Here we calculate luminosity and spectrum produced by relativistic breakouts. In order to do so, improve analytic description...