Observations of the “Bump”
associated with GRB 050525A
Massimo Della Valle
INAF-Arcetri
Venezia, 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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GRB 980326
Bloom et al. 1999
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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 reemission 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 (?) Bumps
GRB 970228
Bloom et al. 1999
GRB 990712
Reichart et al. 1999; Galama et al. 2000
Bjornsson et al. 2001
Price et al. 2003
GRB 991208
GRB 000911
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Lazzati et al. 2001
Castro-Tirado et al. 2001
Garnavich et al. 2003
SN 2002lt/GRB 021211 z=1.006
“rebrightening”
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GRB 050525A
Della Valle et al. 2006
~ 5d
Fecho(t) ~ DTSN FSN f(t)
DTSN ~ 40d
(Patat et al. 2005)
(for rigorous treat. Chevalier 1986)
 DTAG ~ 40/100=0.4d
“standstill”
~ 500d
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Echoes light can be an interesting alternative to the SN interpretation
Stanek et al. 2005
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Della Valle et al. 2006
Spectrum
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GRB 050525A and SN 2005nc
Blustin et al. 2005
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)=0.1 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
Only GRB-SNe
show strong radio
emission.
No-GRB-HNe,
like 2002ap, do
not.
Either no jets or
low-density
environments.
Soderberg et al.2006
The presence of
relativistic jets is
the mark between
GRB/XRF-HNe
and ordinary
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SNe/HNe