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

2. 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. 3 Bloom et al. 1999 GRB 980326

4. 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. 5 Family Portrait of SN (?) Bumps Reichart et al. 1999; Galama et al. 2000 Bjornsson et al. 2001 Lazzati et al. 2001 Price et al. 2003 Castro-Tirado et al. 2001 GRB 970228 GRB 990712 GRB 000911 GRB 991208 Garnavich et al. 2003 Bloom et al. 1999

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

7. 7 Della Valle et al. 2006 GRB 050525A standstill ~ 500d ~ 5d F echo (t) ~ T SN F SN f(t) (for rigorous treat. Chevalier 1986) T SN ~ 40d (Patat et al. 2005) T AG ~ 40/100=0.4d

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9. 9 The progenitors collapses or coalesceces, forming a spinning BH Progenitor 4x10 11 cm Campana et al. 2006 …and the colliding shells give rise to the GRB GRB location <10 14 cm The energy escapes in the form of jets… observer Afterglow location <10 18 cm Kinetic Energy Shock dissipation Afterglow Dense cloud

10. 10 Stanek et al. 2005 Echoes light can be an interesting alternative to the SN interpretation

11. 11 Della Valle et al. 2006 Spectrum

12. 12 GRB 021211 Della Valle et al. 2003 (MISTICI Collaboration)

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14. 14 GRB 021211

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32. 32 Ca Della Valle et al. 2003

33. 33 SUPERNOVA (1994I-like or 2002ap) The spectrum of the afterglow associated with GRB 021211, obtained during the bump, reveals the presence of a broad absorption feature (FWHM~150 A), blueshifted by ~15000 km/s, which has been identified with CaII H+K SUPERNOVA (1994I-like or 2002ap)

34. 34 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 T 90 =9s AG radio (Cameron & Frail 2005) IR (Garnavich et al. 2005) Blustin et al. 2005 E(B-V)=0.1 Blustin et al. 2006 A R ~ 0.35 A R ~ 0.25 (MW)

35. 35 Follow-up at TNG, NTT and VLT+FORS2

36. 36 z=0.606 Foley et al. 2005

37. 37 Follow-up at TNG, NTT and VLT+FORS2 Della Valle et al. 2006

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44. 44 Follow-up at TNG, NTT and VLT+FORS2 Della Valle et al. 2006 Spectrum

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46. 46 +5 days

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48. 48 + 10 days

49. 49 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.

50. 50 SN 1994I GRB 021211/SN 2002lt

51. 51 Conclusions contd 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).

52. 52 FINE

53. 53 Soderberg et al. 2005

54. 54 Soderberg et al. 2005 XRF 040701 fainter than 2002ap/SN 1994I by 3-6 mag (i.e. M V ~ -13/-15)

55. 55 Radio light curves of HNe Soderberg et al.2006 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