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Observations of the “Bump” Observations of the “Bump” associated with GRB 050525Aassociated with GRB 050525A

Massimo Della ValleINAF-ArcetriVenezia, Giugno 2006

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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

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Bloom et al. 1999GRB 980326

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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)

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Family Portrait of SN (?) Family Portrait of SN (?) Bumps Bumps

Reichart et al. 1999; Galama et al. 2000

Bjornsson et al. 2001

Lazzati et al. 2001

Price et al. 2003

Castro-TiradoCastro-Tirado et al. 2001et al. 2001

GRB 970228GRB 990712

GRB 000911

GRB 991208

Garnavich et al. 2003

Bloom et al. 1999

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SN 2002lt/GRB 021211 z=1.006

“rebrightening”

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Della Valle et al. 2006GRB 050525A

“standstill”

~ 500d

~ 5d

Fecho(t) ~ TSN FSN f(t) (for rigorous treat. Chevalier 1986)

TSN ~ 40d (Patat et al. 2005) TAG ~ 40/100=0.4d

10Stanek et al. 2005

Echoes light can be an interesting alternative to the SN interpretation

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Della Valle et al. 2006

Spectrum

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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)

Blustin et al. 2005

E(B-V)=0.1 Blustin et al. 2006

AR ~ 0.35

AR ~ 0.25 (MW)

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Follow-up at TNG, NTT and VLT+FORS2

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z=0.606

Foley et al. 2005

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Follow-up at TNG, NTT and VLT+FORS2

Della Valle et al. 2006

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Follow-up at TNG, NTT and VLT+FORS2

Della Valle et al. 2006

Spectrum

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+5 days

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+ 10 days

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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.

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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).

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FINE

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Soderberg et al. 2005

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Soderberg et al. 2005

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

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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