GRB-Supernova observations: State of the art

Probing the Supernova Mechanism by Observations 16 July 2012

Elena Pian

INAF, Trieste Astronomical Observatory &Scuola Normale Superiore di Pisa, Italy

GRBs are brief flashes of soft -ray radiation (100 keV), discovered in the 1970’s, the origin of which was not known

until 1997

CGRO-BATSE

The GRB distribution is isotropic

8 hours 3 days

GRB970228: first detection of X-ray and optical afterglow

6 monthslater

Costa et al. 1997

Van Paradijs et al. 1997

Fields of GRBs

(physical scale across each image is about 7 kpc)

Starling et al. 2011

Early Multiwavelength Counterparts

(z = 0.937)

Bloom et al. 2008

(z = 6.29)

(z = 1.6)

Bimodal distribution of GRBdurations

short

long

Different progenitors: SNevs binary NS mergers

Kulkarni 2000Duration (s)

Isotropic irradiated –ray energy vs redshift

Long GRB

Short GRB

Relativistic jet model of a GRB:“Unified scheme” for GRBs and Sne?

GRB980425Supernova 1998bw (Type Ic)

z = 0.0085

Galama et al. 1998

GRB-Supernovae with ESO VLT+FORS

z = 0.168

z = 0.105

GRB031203/SN2003lw

GRB-SNe have kinetic energies exceeding those of normal SNe byan order of magnitude (e52 erg)Hjorth et al. 2003

Malesani et al. 2004

X-ray Flashes

Swift was triggered by XRF060218 on Feb 18.149, 2006 UT

Prompt event

afterglow

Shock breakout or jet cocoon interaction with CSM,Or central engine, or synchrotron + inverse Compton ?

Campana et al. 2006

SN

UVOT

z = 0.033

M(56Ni) = 0.2 MsunM(progenitor) = 20 Msun

Mass of remnant is compatibleWith neutron star rather thanBlack hole

Pian et al. 2006; Mazzali et al. 2006; Ferrero et al. 2006

SN2006aj (z = 0.033)

Starling et al. 2011

X-ray light curves of low-redshift GRBs

Shock breakout in SN2010bh (Cano et al. 2011)

Starling derives an initial radius of 8e11 cm from X-ray spectroscopy

GRB/XRFs associated with supernovae

Zhang et al. 2012, arXiv:1206.0298

z = 0.28

GRB120422A/SN2012bz (z = 0.283)

Perley et al. 2012

26 April 2012

VLT FORS spectra of GRB120422A/SN2012bz

z = 0.283

SN1998bw

SN2006aj

GRB091127/SN2009nz (z = 0.49)

Cobb et al. 2010 Berger et al. 2011

Light Curves of GRB and XRF Supernovae at z < 0.3

Melandri et al. 2012

Photospheric velocities of Type Ic SNe

Pian et al. 2006Bufano et al. 2012

Properties of GRB-SNe

Berger et al. 2011

light curves of the optical afterglow of the “normal” long GRB060614 (z = 0.125)

Della Valle et al. 2006

Gal-Yam et al. 2006

spectra of GRB060614 (z = 0.125): no SN features

GMOS, 15 Jul 06

VLT, 29 Jul 06

Della Valle et al. 2006Gal-Yam et al. 2006

Light curves of Ic SNe: GRB-SNe, broad-lined SNe, normal SNe

-14 GRB060614GRB060505

Della Valle et al. 2006Fynbo et al. 2006Gal-Yam et al. 2006

Summary

Most long GRBs and XRFs are associated with energetic spectroscopically identified Type Ic Sne. SNe associated with GRBs are more luminous than XRF-SNe

Mechanisms:Collapsar: a BH forms after the core collapses, and rapid accretion on it feeds the GRB jet. Magnetar: the NS spin-down powers a relativistic jet

Not all long GRBs are accompanied by energetic Type Ic Sne

Is the early high energy emission due to an engine (jet) or to shock breakout? Late time SN spectroscopy may be a tool to investigate this via reconstruction of supernova explosion geometry (VLT; Subaru)