Professor Tsvi PiranTsvi Piran, Ph.D. is Schwarzmann University Chair, Racah Institute of Physics, Hebrew University. He is also on the Editorial Boards of the Journal of Cosmology and Astroparticle Physics and the International Journal of Modern Physics D.
Tsvi’s scientific fields of interest include relativistic astrophysics, cosmology, general relativity, high energy astrophysics, and space research.
At the time that most astronomers believed that Gamma-Ray Bursts (GRBs) were galactic, Tsvi proposed that GRBs originate from cosmological neutron star binary mergers, a model that is generally accepted today. In 1992 as soon as BATSE results were announced Tsvi was the first to realize that they imply that GRBs are cosmological. During the early nineties when the cosmological vs. galactic debate took place he was one of the strongest and most vocal proponents of cosmological origin, that was confirmed in 1987 with the discovery of Cosmological redshifts from GRB’s afterglows. Even before the cosmological origin of GRBs was discovered he laid the foundation to the generally accepted cosmic fireball model.
He was the first to suggest that GRBs herald the formation of newborn black holes. Later on he established the theory of GRB afterglows and of GRB jets. His extensive review papers are the standard literature on this subject.
Before working on GRBs Tsvi was among the founders of numerical relativity. In 1985 he wrote the first code capable of calculating the collapse and formation of a rotating black hole and the resulting gravitational radiation waveform. Detection of this waveform will provide the ultimate proof for the existence of black hole.
In addition to these works his contributions range over a wide selection of problems in Relativistic Astrophysics. In a seminal contribution he demonstrated the critical dependence of the stability of accretion disks on the cooling and heating mechanisms. He was the first to point that inflation is a generic phenomenon involving any scalar field (without requiring a specific potential) and later on to show that in fact the onset of inflation is not fully generic and it requires specific initial conditions, a concept whose full implications were not addressed up to now.
Tsvi was the first to suggest and show that cosmic biasing depends on galaxy types and that different galaxies are distributed differently in the universe. A concept that seems obvious today but was controversial when proposed in the late eighties. His work includes also contributions to the general theory of relativity such as one of the strongest counter examples to the cosmic censorship hypothesis and the demonstration of instability of the inner structure of black hole.
He is coeditor of Dark Matter In The Universe. His papers include GRBs Light Curves — Another Clue on the Inner Engine, Spectra and Light Curves of Gamma-Ray Burst Afterglows, Gamma-Ray Bursts and the Fireball Model, The Physics of Gamma-Ray Bursts, Jets in GRBs, Gamma-ray bursts as the death throes of massive binary stars, Neutron star and black hole binaries in the Galaxy, Variability in gamma-ray bursts: A clue, Can internal shocks produce the variability in gamma-ray bursts?, and Predictions for the very early afterglow and the optical flash. Read the full list of his publications!
Tsvi earned his BSc (Cum Laude) in Physics at Tel Aviv University in 1970. He earned his MSc (Magna Cum Laude) in Space Science at Tel Aviv University in 1972. He earned his Ph.D. in Physics at Hebrew University in 1976.
Read Gravitational Waves That Are “Sounds of the Universe” and Astronomers Link Old Stars And Mysterious Cosmic Explosions. View his Facebook page. Read his ResearchGate profile and his Wikipedia profile.