Tsvi Piran

In addition to Piran's work as an astrophysicist, he has served from 2005 until 2009 as the dean of the Hebrew University School of Business Administration. During this term he has made revisions in the school.

At a time when most astronomers believed that GRBs were galactic (see however an earlier suggestion by Bohdan Paczynski ) with Eichler, Livio and Schramm, Piran proposed that GRBs originate from cosmological neutron star binary mergers, a model that is generally accepted today. 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, which was confirmed in 1997 with the discovery of cosmological redshifts from GRB's afterglow. Even before the cosmological origin of GRBs was discovered Piran laid the foundation to the generally accepted cosmic fireball model. He suggested that GRBs herald the formation of a newborn black hole. Later on, together with Re'em Sari and other collaborators, Piran further developed the theory of GRB afterglows, in a paper which has by now more than 1000 citations, and of GRB jets. His review papers are the standard literature on this subject.

Before working on GRBs, Piran made important contributions to numerical relativity, the numerical solution of Einstein's equations. In 1985 he wrote the first numerical code calculating the collapse and formation of a rotating black hole and the resulting gravitational radiation waveform. This waveform shows relaxation towards the quasinormal modes of the black hole that forms. Detection of this waveform in the future by advanced gravitational radiation detectors might provide the ultimate proof of the existence of a black hole.

Tsvi Piran (born May 6, 1949) is an Israeli theoretical physicist and astrophysicist, best known for his work on Gamma-ray Bursts (GRBs) and on numerical relativity. The recipient of the 2019 EMET prize award in Physics and Space Research.