A Radio Perspective on the GRB-SN Connection

Alicia SoderbergMay 25, 2005 – Zwicky Conference

Gamma-Ray Bursts

• highly relativistic (~100) jets ( ~ few degrees) -ray emission

• mildly relativistic (<10) ejecta produce “afterglow” emission

• imply central engine

• spherical explosion produces non-relativistic (<1) optical SN emission (Type Ibc)

• Rate: ~2.5 x 102 Gpc-3 yr-1

Type Ibc Supernovae

?

Type Ibc Supernovae

• NO H in optical spectra (10%)

• NO -ray emission

• NON-relativistic, <1, synchrotron emission from mildly asymmetric ejecta

• NO evidence for central engines

• spherical explosion drives non-relativistic optical SN

• Rate: 4.8 x 104 Gpc-3 yr-1~ 0.5 % of SNe Ibc associated with GRBs

GRBs

?

SNe Ibc

Spherical + Jet Framework

connection

(Galama et al., 1998; Pian et al. 2000)

z=0.0085 (~36 Mpc)

SN1998bw discovered within BeppoSAX error box for GRB 980425

Two key probes:

Optical & Radio

GRB980425 and Type Ic SN1998bw“A GRB/SN Connection”

GRB980425 and Type Ic SN1998bw“A luminous local SN”

Optical emission requires:

~ 0.5 M Nickelv ~ 60,000 km/s

(Iwamoto et al.1998; Woosley et al. 1999)

(Galama et al. 1998)

8.5 GHz

E ~ 5 x 1049 erg

~3 ejecta

(Kulkarni et al.1998; Li & Chevalier 1999)

What fraction of SNe Ibc are like SN1998bw?

GRB980425 and Type Ic SN1998bw“The most luminous radio SN”

RADIO is most sensitive to relativistic ejecta

1. Synchrotron emission traces the fastest ejecta

2. The synchrotron peak is near/below the radio band.

3. Higher frequencies dominated by other processes.

Observe EVERY (optically selected) SN Ibc within 100 Mpc

Caltech/NRAO/ATCA Radio Type Ibc SN Survey

VLA Surveyof Type Ibc Supernovae

Results:11 detections

82 upper limits

(Soderberg et al. 2005; Berger et al. 2002,03; Kulkarni et al. 1998)

Radio bright SN Ibc are rare and diverse.

Equipartition Energy and Velocity

Out of 93 SNe, none like SN1998bw and/or GRBs

< 1% GRB/SN

€

∝ d−1/17Fν ,p8 /17ν p

−1 μas

E ∝ d2Fν ,p4 ν p

−7θ−6 erg

Radio Analysis of SN 2003L

(Soderberg et al., 2005a)

Detailed Modeling:

E ~ 1049 erg

v ~ 0.2c

r ~ t

B ~ r -1

n ~ r -2

Mdot ~ 10-5 M/yr

log (time)

log

(F)

“Hidden” GRB Jets in Local SNe Ibc

No -rays seen

log (time)

log

(F)

“Hidden” GRB Jets in Local SNe Ibc

Afterglow begins

log (time)

log

(F)

“Hidden” GRB Jets in Local SNe Ibc

log (time)

log

(F)

“Hidden” GRB Jets in Local SNe Ibc

Type Ibc SN!

log (time)

log

(F)

“Hidden” GRB Jets in Local SNe Ibc

log (time)

log

(F)

“Hidden” GRB Jets in Local SNe Ibc

log (time)

log

(F)

“Hidden” GRB Jets in Local SNe Ibc

log (time)

log

(F)

“Hidden” GRB Jets in Local SNe Ibc

log (time)

log

(F)

“Hidden” GRB Jets in Local SNe Ibc

log (time)

log

(F)

t ~ 1 week to few yrs

“Hidden” GRB Jets in Local SNe Ibc

Constraints on Off-Axis GRBs

Out of 53 SNe Ibc,

None house GRBs

< 2% GRB/SN

Broad-lined events

are NO exception

< 20% GRB/BL

(Soderberg et al. in prep)

OPTICAL: Peak SN magnitudes

(Soderberg et al., 2005c)

GRB-SNe do NOT necessarily synthesize more 56Ni than local SNe Ibc.

Conclusions & Future Progress

Radio SNe Ibc are rare and diverse. Their optical properties are similarly diverse and overlap with GRBs

~10 % are radio bright

< 1% with relativistic ejecta

< 2% with off-axis GRB jets

ATA will enable further progress, but SN studies will still be limited by optical discoveries.

We need MORE small telescope campaigns.

Broad-lined SNe Ibc

Radio limits imply

unusual shock

parameters and/or low densities.