1. A burst of new ideas Nature Vol 444 21/28 December 2006 徐佩君 HEAR group meeting 12/26 2006

2. Gamma-ray bursts GRBs are intense and short bursts of  -ray radiation that occur all over the sky ~1/day at very large distances. two main classes of GRBs

3. A burst defies the current scheme “A novel explosive process is required for the  -ray burst GRB 060614”, Gal-Yam et al. “An enigmatic long-lasting  -ray burst not accompanied by a bright supernova”. Della Valle et al. “No supernovae associated with two long-duration  - ray bursts”, Johan P. U. Fynbo et al. “A new  -ray burst classification scheme from GRB 060614”, N. Gehrels et al.

4. GRB 060614 On 14 June 2006, at 12:43 UT BAT on board the Swift satellite Duration: T 90 = 102 s (13-350keV) Detailed information was collected by the Swift BAT, XRT, and UVOT. at the outskirts of a relatively nearby faint dwarf galaxy at a redshift of z=0.125

5. light curve

6. No associated SN ! Any putative SN component must be more than 100 times fainter than the faintest GRB-associated supernova SN2006aj.

7. GRB 060614 short burst category? The spectral lag and low luminosity make it distinct from other long-duration GRBs

8. Afterglow of the burst has a large offset from the star-forming region of the host galaxy. star formation rate: 0.0084M ⊙ /yr small compared with those of normal long GRBs GRB 060614 short burst category?

9. Probabilities A long GRB associated with a collapsing star Its progenitor is different from those of other long GRBs Merger-type short GRB These should not carry the name “short.” Prototype of a different, 3rd category of burst ➔ More data are needed: Whether GRBs with similar properties will be detectable in elliptical host galaxies Thank you !

13. This image shows the durations of the 4B Catalog Gamma-Ray Bursts recorded with the Burst and Transient Source Experiment on board NASA's Compton Gamma-Ray Observatory. The duration parameter used is T90, which is the time over which a burst emits from 5% of its total measured counts to 95%. The data used for the calculation are the BATSE 4 energy channel discriminator data. Lightcurves used for the calculation of T90 are integrated over all 4 channels (E > 20 keV).