| Tsvi Piran | |
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Tsvi Piran
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| Born | May 6, 1949 Tel Aviv, Israel |
| Fields | Theoretical Physics and Astrophysics |
| Institutions | The Hebrew University of Jerusalem |
| Alma mater | The Hebrew University of Jerusalem |
| Doctoral advisor | Jacob Shaham and Joseph katz |
| Notable students | Amos Ori, Eli Waxman, Reem Sari, Ehud Nakar, Jonathan Granot |
Tsvi Piran (born May 6, 1949 in Tel Aviv, Israel) is an Israeli theoretical physicist and astrophysicist, best known for his work on Gamma-ray Bursts and on Numerical Relativity.
At the time that most astronomers believed that GRBs are galactic Piran proposed that GRBs originate form cosmological neutron star binary mergers [1] a model that is generally accepted today. In 1992 as soon as BATSE results were announced Piran was the first[1] to realize that they imply that GRBs are cosmological. During the early nineties when the cosmological vs. galactic debate took place Piran was one of the strongest and most vocal proponents of cosmological origin,[1] that was confirmed in 1987 with the discovery of Cosmological redshifts from GRB's afterglow. Even before the cosmological origin of GRBs was discovered Piran laied the foundation to the generally accepted cosmic fireball model.[1]
Piran was the first to suggest that GRBs herald the formation of a newborn black holes.[1] Later on Piran established the theory of GRB afterglows[1] and of GRB jets[1]his extensive review papers[1] are the standard literature on this subject.
Before working on GRBs Piran was among the founders of Numerical Relatiity. In 1985 he wrote the first code capable of calculating the collapse and formation of a rotating black hole[1] and the resulting gravitational radiation waveform {insert here a picture} Detection, one day of this waveform will provide the ultimate proof for the existence of black hole .
In addition to these works Piran' contributions range over a wide selection of problems in Relativistic Astrophsyics. In a seminal contribution he demonstrated the critical dependence of the stability of f accretion disks on the cooling and heating mechnisms. Piran was the first to point that inflation is a generic phenomenon involving any scalar field (without requiring a specific potential)[1] 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.. He 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 controvercial when proposed in the late eighties .[1]Piran's work include also contributions to the general theory of relativity such as one of the strongest counter examples to the Cosmic Censhorship Hypothesis[1] and the demonstration of instability of the inner structure of black hole.[1]
Awards Landau Prize for a distinguished PhD thesis - 1976
Distinguished Moore Fellowship Caltech - 2005
ERC Advanced Reaserch Grant - 2009