Research

Current Fields of Research

• Cosmology: Dark Matter, Dark Energy, Tests of General Relativity and the standard cosmological model.
• High Energy Astrophysics: A Unified Theory of High Energy Astrophysical Phenomena (Gamma Ray Bursts, Cosmic Rays, Cosmic Gamma Rays and Neutrinos, Cooling Flow Clusters).
• Particle Astrophysics: Pulsars, Anomalous Pulsars, Neutron Stars, Quark Stars and Stellar Black Holes.
• Astrobiology: Astrophysical Mechanisms of Mass Extinctions; Solar Activity and Cosmic Rays Effects on Terrestrial Biology and Climate.

Major Scientific Achievement

Solution of the Gamma Ray Burst (GRB) mystery long before it was discovered/verified by observations, its implementation in a remarkable successful theory of GRBs and their afterglows, and suggesting their major implications for astrophysics, cosmology, cosmic rays and life extinctions on life supporting planets. (proposed together and verified step by step with various collaborators):

• GRBs Origin:  GRBs are cosmological in origin. Long GRBs are mainly produced in stripped envelope supernova (SN) explosions (the LGRB-SN association, publications #65 (1987) and # 55 (1992)). SHBs are produced in merger of neutron stars, phase transition in compact stars, and mass accretion on compact stars (publications # 65 (1987), # 55 (1992), # 13 (2009).
• GRB Production Mechanism: The prompt gamma ray emission is produced by inverse Compton scattering of glory light around striped envelope supernova by a highly relativistic jet of plasmoids ejected in such events (publications # 50 (1995), # 44 (1997) # 25 (2004). [Mounting observational evidence from Light-curves, Polarization, Spectrum, Spectral Evolution, and Correlations among observables, was exposed in several following publications).
• Afterglow Mechanisms: Synchrotron and synchrotron self Compton (SSC) emission during the deceleration of the highly relativistic jet of plasmoids in the circumstellar/interstellar medium, which correctly predict all the main observed properties of the the broad band afterglow (canonical behviour, break origin, chromatic behaviour, spectral evolurtion, closure relations (e.g., publications # 37 (2002), # 12 (2009), # 4 (2013), # 2 (2013)).
• Long Gamma Ray Bursts Trace The Star Formation History (publication # 2, and arXiv:astro-ph/9503105).
• Terrestrial life extinctions by Galactic GRBs. (publication # 45).

Research Experience

• Nuclear Physics
• Plasma Physics
• Particle Physics
• Astrophysics and Cosmology

Main Original Ideas and Achievements

Nuclear Physics

• Diffraction Model For Direct Nuclear Reactions.
• Semiclassical Models For Low and High Energy Heavy Ion Collisions.

Plasma Physics

• Fusion chain reaction in a cold matter (with Y. Grunzweig, A. Peres, M. Revzen and A. Ron).

Particle Physics

• Diffraction model for elastic Scattering (with Y. Dothan, M. Kugler and S. Nussinov).
• Absorption model for two body reactions.
• First demonstration of particle properties from the quark model (with V. F. Weisskopf).
• Quark model for high energy particle-nucleus and nucleus-nucleus collisions (with Y. Afek, G. Berlad and G. Eilam).

Particle Astrophysics

• Analytic calculation of the atmospheric neutrino background.
• Terrestrial tests of the neutrino oscillations solution to the solar neutrino problem (with A. Mann).
• The day/night effect for solar neutrinos (With A. Mann).
• Predicting and alerting IMB and Kamiokande proton decay detectors of the neutrino signal from SN1987a (with J. Bahcall and T. Piran).
• Limits on neutrino properties from the neutrino signal from SN1987A.
• Neutrino anihilation role in core collapse SN explpsions (with J. Goodman and S. Nussinov).
• GRBs from neutrino annihilation in neutron star mergers (with J. Goodman and S. Nussinov).

Astrophysics

• A cosmic GRB-SN association (with B. Kozlowski, S. Nussinov and R. Ramaty).
• A GRB-cosmic rays association (with B. Kozlowski, S. Nussinov and R. Ramaty).
• Jetted GRBs from accretion induced stellar collapse and from mergers of neutron stars (with N. Shaviv).
• Collimated afterglows from jetted GRBs.
• GRB origin of Galactic cosmic rays (with R. Plaga).
• The cannonball model of GRBs (with A. De Rujula).
• The cannonball model of GRB afterglows (with S. Dado and A. De Rujula).
• Afterglow Evidence for the GRB-SN association (with S. Dado and A. De Rujula).
• A heat source of cooling flow clusters (with S. Colafrancesco and A. De Rujula).
• Solution of the cosmic-ray origin puzzle (with A De Rujula).
• A unified theory of high energy astrophysical phenomena (with A. De Rujula).

Cosmology

• Long distance tests of general relativity.
• A cosmic MeV neutrino background from past supernova.
• A cosmic high energy neutrino background from AGN (with N. Shaviv).
• A cosmic-ray origin of the extragalactic gamma ray background (with A. De Rujula).

Astrobiology

• Terrestrial life extinctions by Galactic GRBs (with A. Laor and N. Shaviv).