On the classification of GRBs and their occurrence rates

On the classification of GRBs and their occurrence rates

Prof. Remo Ruffini (ICRANet)

Auditório do 5 andar, às 16h.

GRBs have been traditionally considered to be single component systems characterized by relativistic jet emission and classified by their phenomenological properties into 'short' GRBs, those lasting less than two seconds, and 'long' GRBs, the remaining ones.

The discovery of their cosmological origin and associated tremendous energies comparable to the energy emitted by the billions of galaxies in our past visible universe, each composed of 100 billion stars, did not modify this general simplistic approach: the origin of their energy was shrouded in mystery, although the general presence of a black hole in the system was often considered.

In a series of papers over the past decade, a different scenario has emerged: GRB progenitors, far from being single component systems, are in fact multiple component systems. These systems evolve in the merger process which may lead to the formation of a black hole and a newly born neutron star or to more massive newly born neutron stars.

It also traditionally believed that each and every GRB originates from accretion in an already formed black hole system. Instead, in this new classification scheme, it is clear that only some of the GRB families imply the formation of a black hole, namely the most energetic ones.

What is the most beautiful and outstanding aspect of the new understanding is that in these cases one can identify the moment of the formation of the black hole within the evolution of the GRB, and its activity can be observed in the precise moment of its formation.

 

Remo Ruffini 

Nascido em 17 de maio de 1942, em Briga Marittima, Italia, é atualmente diretor do ICRANet (International Center for Relativistic Astrophysics Network) e do programa internacional de pós-graduação International Relativistic Astrophysics PhD (IRAP-PhD). Foi professor de física teórica na Universidade de Roma 'La Sapienza' entre 1978 e 2012.

Em sua vida acadêmica, trabalhou com nomes importantes da física teórica do século passado, como Pascual Jordan, Abdus Salam - com quem fundou os Marcel Grossmann Meetings em 1984 -, Demetrius Christodoulo, Tibaud Damour, entre outros.

Seus trabalhos clássicos com John A. Wheeler popularizaram o conceito de buracos negros e, na década de 1960, juntamente com Riccardo Giacconi, participou da identificação de Cignus X-1 como o primeiro buraco negro diretamente observado na Via Láctea, com dados do satélite Uhuru.

Remo Ruffini foi membro do Instituto de Estudos Avançados de Princeton e Presidente do Comitê Científico da Agência Espacial Italiana. Em 1972, recebeu o Prêmio Cressy Morrison, da Academia de Ciências de Nova York.