Observations of the “Bump” associated with GRB 050525A

1. Observations of the “Bump” associated with GRB 050525A Massimo Della Valle INAF-Arcetri Venezia, Giugno 2006

2. SN/GRB connection • Local Universe: GRBs – SNe-Ic(BL) GRB 980425/SN 1998bw; GRB 030329/SN 2003dh; GRB 031203/SN 2003lw and GRB 060218/SN 2006aj • High-z (z > 0.2): Bumps in the late stages of the afterglows • Hosts of the GRBs: star forming galaxies

3. GRB 980326 Bloom et al. 1999

4. Are the bumps representative of signatures of incipient SNe? Or they can be produced by different phenomena as dust echoes or thermal re-emission of the afterglow or thermal radiation from a pre-existing SN remnant(e.g. Esin & Blandfors 2000; Waxman & Draine 2000; Dermer 2003)

5. Bloom et al. 1999 Family Portrait of SN (?) Bumps GRB 990712 GRB 970228 Reichart et al. 1999; Galama et al. 2000 Bjornsson et al. 2001 Price et al. 2003 GRB 991208 GRB 000911 Castro-Tiradoet al. 2001 Garnavich et al. 2003 Lazzati et al. 2001

6. SN 2002lt/GRB 021211 z=1.006 “rebrightening”

7. Della Valle et al. 2006 GRB 050525A ~ 5d Fecho(t) ~ DTSN FSN f(t) (for rigorous treat. Chevalier 1986) DTSN ~ 40d (Patat et al. 2005) DTAG ~ 40/100=0.4d “standstill” ~ 500d

8. Echoes light can be an interesting alternative to the SN interpretation Stanek et al. 2005

9. Della Valle et al. 2006 Spectrum

10. Blustin et al. 2005 GRB 050525A and SN 2005nc Discovered by Swift (Band et al. 2005) solid = 15-25 keV dots = 25-50 keV short dashed = 50-100 keV long dashed = 100-350 keV T90=9s AG radio (Cameron & Frail 2005)  IR (Garnavich et al. 2005) • E(B-V)=0.1Blustin et al. 2006 • AR ~ 0.35 • AR ~ 0.25 (MW)

11. Follow-up at TNG, NTT and VLT+FORS2

12. z=0.606 Foley et al. 2005

13. Della Valle et al. 2006 Follow-up at TNG, NTT and VLT+FORS2

20. Della Valle et al. 2006 Spectrum Follow-up at TNG, NTT and VLT+FORS2

22. +5 days

24. + 10 days

25. Conclusions • Spectroscopic observations of the Bump associated with GRB 050525A are suggestive for the presence of a SN (~ 0.4 mag fainter than 1998bw) therefore excluding the presence of an echo light. Time lag between SN and GRB? Within ~1d. SN 2005nc has a faster rising time than SN 1998bw, about 10-11d rather than 14-15d (SN 1998bw in B band). • Maeda et al. (2006) show that asymmetric SNe peak earlier if observed along their polar axis. • Since GRBs at high-z are likely viewed on-axis IF asymmetry play an importan role in the SN-GRB phenomenon  SNe associated with high-z GRBs should have “ on average” faster rising times than GRB-SNe observed locally.

26. Conclusions cont’d • Only two bumps out of about a dozen have been spectroscopically observed. The distributions of the absolute mag at max of bumps and standard Ibc are statistically indistinguishable  do they derive from the same (very heterogeneous) SN population? • SNe associated with local GRBs belong to the bright tail of GRB-SN distribution  observational bias (scanty statistic) ? Or SNe associated to local and cosmological GRBs have different absolute mag at max? Evolution with z ? (metallicity).

27. FINE

28. Soderberg et al. 2005

29. Soderberg et al. 2005 XRF 040701 fainter than 2002ap/SN 1994I by 3-6 mag (i.e. MV ~ -13/-15)

30. Radio light curves of HNe Only GRB-SNe show strong radio emission. No-GRB-HNe, like 2002ap, do not. Either no jets or low-density environments. The presence of relativistic jets is the mark between GRB/XRF-HNe and ordinary SNe/HNe Soderberg et al.2006