Lecture 5 GammaRay Bursts Light extinction GRBs are

Lecture 5: Gamma-Ray Bursts Light extinction:

GRBs are brief flashes of soft -ray radiation ( 100 ke. V), discovered in the 1970’s, the origin of which was not known until 1997 CGRO-BATSE

CGRO spectrum of a GRB

CGRO-BATSE (Fishman & Meegan 1995) Light curves of GRBs Fluence ~ if cosmological relativistic conditions are implied: Lorentz factor

The GRB distribution is isotropic

long short Bimodal distribution of GRB durations Different progenitors: SNe vs binary NS mergers Duration (s) Kulkarni 2000

Precisione di BATSE 1 grado

1996 -2002: The Beppo. SAX revolution Wide Field Cameras

Precisione delle WFC di BSAX Precisione di BATSE 1 grado

GRB 970228: first detection of X-ray and optical afterglow 8 hours 3 days Van Paradijs et al. 1997 Costa et al. 1997 6 months later

“Firecone” model: relativistic shocks in a jet ~ 100 ~ 10

Early Multiwavelength Counterparts (z = 6. 29) (z = 0. 937) (z = 1. 6) Bloom et al. 2008

Redshift Measurement Djorgovski et al. 1999

Bloom et al. 1998, 1999 Host galaxies exhibit emission lines of star formation: [O II], [O III], Balmer and Paschen series

Isotropic irradiated gamma–ray energy vs redshift Long GRB Short GRB

GRB 980425 Supernova 1998 bw (Type Ic) z = 0. 0085

Example of Supernova underlying GRB optical afterglow (z = 0. 695) Galama et al. 1999

Light curves of Ic SNe: GRB-SNe, broad-lined SNe, normal SNe