CENTER FOR APPLIED MATHEMATICS AND THEORETICAL PHYSICS
UNIVERZA V MARIBORU $\bullet$ UNIVERSITY OF MARIBOR
KREKOVA 2 $\bullet$ SI-2000 MARIBOR $\bullet$ SLOVENIA
Phone +(386) (2) 2355 350 and 2355 351 $\bullet$ Fax +(386) (2) 2355 360
Robnik@uni-mb.si $\bullet$ www.camtp.uni-mb.si
PROF.DR. MARKO ROBNIK, DIRECTOR

Seminarsko predavanje
Centra za uporabno matematiko in teoretično fiziko

GAMMA-RAY BURSTS, UPDATED

Professor Dr. Wolfgang Kundt
Institut für Astrophysik, Universität Bonn
Bonn, Germany

Abstract: Earth is hit daily by some four gamma-ray bursts (GRBs), with peak energies between $10 KeV$ and several $MeV$, with broad, hard power-law spectra, prompt plus afterglow, ranging from radio frequencies to $TeV$ energies (in so far exceptional cases), and with occasional precursors (by $\le 1$ hour), and occasional long tails (by $\le$ hours). Where do they come from? Their temporal fine structure asks for sources of size $s \le 20 km$, their power obeys the Eddington constraint ( $\le 10^{38.5} erg/s$) for nearby Galactic neutron stars ( $10^{-2} \le d/Kpc \le 0.5$), and their formerly two-humped lightcurves are about to fuse into a single-humped one, peaked at $1 s$, with typical burst durations of $10^2 s$, whereby subpulses have softening FRED structure, (Fast Rise Exponential Decay, with temporally decreasing hardness). The long bursts (Delta(t)$\ge$ 1s) look like superpositions of short bursts (Delta(t) $\le 1s$), whereby the short bursts reveal periodicities of $\le 10 s$ in their faint tails. The spectra of GRB afterglows can look reminiscent of SN explosions, cf. Nature 444, 1044 and 1055 (06). To me, all GRBs can be understood as coming from spasmodic, clumped accretion by the newly born, or dying (Galactic) pulsars, the latter of spindown age $\le 10^{6.4}$ years.

Seminarsko predavanje bo v petek, 20. aprila 2007 ob 15:15 uri v seminarski sobi CAMTP, Krekova 2, pritličje desno. Vljudno vabljeni vsi zainteresirani, tudi študentje.

Prof.Dr. Marko Robnik
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