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LNGS Summer Institute 2005. GRB: Modern Status. Elena Pian - INAF, Trieste Astronomical Observatory, Italy. Outline. Connection between Supernovae and long GRBs / X-ray Flashes Swift: early GRB counterparts Short Gamma-Ray Bursts. long. Bimodal distribution of GRB durations. short.

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LNGS Summer Institute 2005

GRB: Modern Status

Elena Pian - INAF, Trieste Astronomical Observatory, Italy


Connection between Supernovae and long GRBs / X-ray Flashes

Swift: early GRB counterparts

Short Gamma-Ray Bursts




of GRB



The progenitors of

short bursts are still

to be identified!!!

Binary neutron stars?

Kulkarni 2000


Supernova 1998bw (Type Ic)

z = 0.0085

GRB030329/SN 2003dh

z = 0.168


Photospheric velocity

Si II 6355

Hjorth et al. 2003

Grb031202 sn2003lw

z = 0.105


Malesani et al. 2004

z = 0.695


Galama et al. 2000


Fynbo et al. 2004

Soderberg et al. 2004

Tominaga et al. 2004

Is there a unifying scheme for SNe and GRBs?

Four clear cases of SN-GRB association have been detected spectroscopically, all are Type Ic SNe. In all of these, the SN is very powerful (high luminosity, large kinetic energy), i.e. it is a “Hypernova” (Paczynski 1998; Iwamoto et al. 1998)

SNe with hypernova characteristics have been detected, although they are not accompanied by a GRB (SNe 1997dq, 1997ef, 2002ap, 2004aw…); see also IPN survey

The rate of GRBs (taking into account collimation) corresponds to the relative rate of hypernovae with respect to the total number of Ic SNe (i.e. ~5%, Podsiadlowski et al. 2004)

Do all hypernovae have jets and produce GRBs, so that only those aligned with the line of sight are detected?

Can we test this “unified scenario”?

Signatures of asphericity in sn1998bw

In nebular spectra of SN1998bw, Fe lines are broader than O lines

A spherically symmetric explosion of a massive star would result in the opposite

Signatures of asphericity in SN1998bw

[OI] 6300A


[FeII] 5200A


SN 1998bw

0.7 s lines

1.5 s

2D explosion: KE=11foe, MBH(final)=5.9M, M(56Ni)=0.11M



Maeda et al. 2002

Spherical lines



Aspherical explosion: confined nucleosynthesis

[OI] 6300A

FeII] 5200A

SN 1998bw


Orientation 15 deg

Maeda et al. 2002

The bright type ic sn 2003jd
The bright Type Ic SN 2003jd lines

Discovered 25 Oct 2003; distance: 80 Mpc

Courtesy: K. Kawabata

The bright type ic sn 2003jd1
The bright Type Ic SN 2003jd lines

  • SN 2003jd was as bright at peak as SN1998bw (Mv = -18.7)

  • Early-time spectra had broad lines, similar to hypernova SN2002ap

  • No GRB or XRF

Sn 2003jd
SN 2003jd: lines

an aspherical SN viewed off-axis


Subaru+FOCAS, at 330 days

Keck+LRIS, at 370 days

The [O I] 6300A line shows a double peak, suggesting an explosion similar to SN1998bw but viewed ~70° from the axis


Mazzali et al. 2005, Science 308, 1284

SN2003jd: an aspherical supernova viewed off-axis lines



Mg I]

[Ca II]

[Fe II]

[O I]

Mazzali et al. 2005

[O I] nebular lines


[O I] line:



on viewing


Mazzali et al. 2005

Was sn 2003jd also a grb hn
Was SN 2003jd also a GRB/HN? lines


  • Radio and X-ray upper limits are not in contradiction with a GRB viewed off-axis


Mazzali et al. 2005

Swift lines

Launched 20 Nov 2004

Examples of Swift-XRT light curves lines

Steep decline common

Gets shallower around here

Nousek et al. 2005

GRB990123 lines



2-10 keV

15-28 keV


Maiorano et al. 2004

Corsi et al. 2004

GRB990123 (z = 1.6) lines

Fruchter et al. 1999

GRB041219a: Optical flash from internal shocks lines


Internal shock


Reverse shock

Akerlof et al. 1999; Vestrand et al. 2005

Optical Flashes lines

Guidorzi et al. 2005

GRB050502a lines

z = 3.793

Liverpool 2m telescope

+ Robonet consortium

Forward shock in ISM

In variable density


Guidorzi et al. 2005

1 kev x ray light curve

GRB050509b (T lines90=0.04s)

1 keV X-ray light curve

BAT+XRT emission consistent with a single decay rate of 1.2±0.09

Gehrels et al. 2005

GRB050509b lines

Host galaxy

Bloom et al. 2005

GRB050509b (z = 0.22) lines

Upper limits on optical

Flux are inconsistent

With supernova

Hjorth et al. 2005

Grb050724 z 0 257

GRB050724 looks long to BAT (T lines90=153s), but would be short to BATSE (<1s)

GRB050724 (z = 0.257)

t-4 ν-1

Host Galaxy of the Short GRB050724 (z = 0.257) lines

SFR < 0.03 Msun/yr

Bloom et al. 2005

Isotropic irradiated lines–ray energy vs redshift


Short GRB


z = 6.29

Conclusions lines

The nebular spectrum of the Type Ic energetic SN2003jd is different

from that of SN1998bw: it exhibits a double-peaked [O I] emission line,

which suggests an aspherical geometry and an equatorial view. This is

consistent with the lack of a detected GRB, and could support a unified

scenario for SNe and GRBs

Are hypernovae the only aspherical SNe Ic? No, normal Ic are polarized

Are hypernovae the most aspherical SNe? Possibly, and this would be

related to the presence of GRBs

In this picture, X-ray flashes may be off-axis GRBs or weaker explosions

Short GRBs have afterglows similar to those of long GRBs. They are

Preferentially detected at lower redshifts, and in galaxies with scarce

Star formation. The evidence that they are not associated with supernovae

is increasing. They are probably double neutron star mergers

Optical flashes probe the early emission mechanisms and circumburst