1. Gamma-ray Bursts and Supernovae
S. R. Kulkarni
California Institute of Technology
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2. TWO BIG QUESTIONS Do all cosmological GRBs have an underlying SN?
Do all nearby (Ib/c) supernovae have gamma-ray emission?
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3. Thanks to D. Frail (NRAO)
E. Berger, D. Djorgovski, D. Fox, F. Harrison, P. Price,
R. Sari, A. Soderberg, S. Yost (Caltech)
P. Price & B. Schmidt (ANU)
H. S. Park (LLNL)
C. Baltay & P. van Dokkum (Yale)
R. Chevalier (UVa)
Say Paul is so valuable that we list him twice
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4. Afterglow Emission: Fireball Model
Supernovae:
Point Explosion in r-n medium
Energy E ~ 1051 erg = 1 FOE
Mejecta ~ 1-10 Msun, Lorentz factor ~ 1.01
Sedov solution (non-radiative phase)
Supernova remnant (radiative phase)
GRBs:
Energy E ~ 1-10 FOE
Mejecta ~ 10-4 Msun, Lorentz factor ~ 100
Relativistic Sedov solution (Blandford-McKee)
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6. Jet Signatures: Optical/X-ray
Piran, Science, 08 Feb 2002
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7. Jet Opening Angles
Angles obtained from epoch of breaks in light curves in the homogeneous conical jet framework
(Caveat: Structured Jets)
Narrow Opening Angles!
only a few degrees wide
Incomplete Statistics for narrow jets
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8. Gamma-ray Energy Release
Frail et al. (2001)
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“Infamous” Frail et al. relation

9. Kinetic Energy of Fireballs
X-ray Afterglow:
L_x(t=8hr)*8hr traces E_Kinetic
Freedman & Waxman
Kumar
Application
Piro et al.
Berger et al.
Curiously E_gamma ~ E_Kinetic
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Berger et al. 2003

10. Long Duration GRBs: Massive Stars
GRB host galaxies are star-forming galaxies
Bloom PhD 2002
High column density/extincted bursts
Galama & Wijers, Djorgovski et al., Piro et al.
Circumburst medium: Wind-fed (011121)
talks by Frail, Chevalier
Most direct evidence comes from associated SNe
GRB Bloom et al. 1999
GRB Galama et al. 2000, Reichart et al. 1999
GRB Garnavich et al. 2002, Bloom et al. 2002
GRB Della Valle et al. 2003
GRB Stanek et al. 2003
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11. Do all cosmological GRBs (c-GRBs) have underlying SNe?
Some c-GRBs have associated bright supernovae
Many either do not have an associated SNe or else V > -19 mag
A wind circumburst medium may not be present around all GRBs
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12. Do all nearby (Ib/c) supernovae have gamma-ray emission?
Once upon a time (25-April-1998), a non-descript burst of gamma-rays occurred in the Southern hemisphere. Both GRB astronomers and SN astronomers who held each other in contempt were excited and this is how our story begins…
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13. GRB & SN 1998bw
GRB , a routine GRB, identified by BeppoSAX
Pian et al. 1999
Identified with bright optical SN with very wide absorption lines
Galama et al. 1998
Identified with super-bright radio SN
Kulkarni et al. 1998
Host Galaxy, distance 44 Mpc
E_gamma ~ erg (isotropic)
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14. High Brightness Temperature for first 3 weeks requires Gamma ~2 to 4
Relativistic Ejecta!
High Brightness Temperature for first 3 weeks requires Gamma ~2 to 4
Kulkarni et al. 1998
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15. Synchrotron Emission: Fast Primer
Basic Parameters: fm, num, nua, spectral index (p)
Example: GRB (nearest c-GRB)
Compute brightness TB and if TB > Teq (1011 K) then
pay either in energy or in size.
(For 1998bw, the parametric fit of Weiler et al. violates the above limit)
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16. SN 1998bw: Underlying Engine!
Chevalier & Li
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17. What is SN 1998bw? A c-GRB but viewed at an angle. Unlikely.
Nakamura; Iwamoto; Granot et al.; Ioka; Salmonson
A supernova with large E_K (and thus relativistic ejecta via whip mechanism)
Energetically Challenged Model Matzner, Tan & McKee
An engine-driven supernova i.e.
a low-luminosity GRB
Kulkarni et al; Bloom et al; Li & Chevalier
We term such nearby SN with gamma-ray emission as supernova-GRBs or s-GRBs
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18. s-GRBs and c-GRBs: Cousins?
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Berger et al. 2003

19. f-GRBs: a new sub-class of c-GRBs?
Afterglow of GRB and GRB were already fading rapidly (t^-2). We term such GRBs as “f-GRBs” (for GRBs with rapidly fading afterglow)
Bloom, Frail & Kulkarni 2003
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20. GRB : an f-GRB?
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Price et al. (2003, submitted to Nature)

21. GRB : Narrow & Wide Jets?
Differing decay index(X-ray, optical & radio)
Optical data shows t_jet~1day (Halpern et al)
A narrow angle jet
(X-ray and optical) +
A wide angle jet (radio)
Frail et al. 1999
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22. Our Working Hypothesis
Major observational difference between ordinary SN and GRBs is the presence of relativistic ejecta.
We suggest that only an underlying ENGINE can drive significant relativistic ejecta.
DIRECT TRACERS: synchrotron emission
strong afterglow emission
INDIRECT (reliable?) TRACERS: broad optical lines
large inferred SN energy release
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23. f-GRBs and wide+narrow jetted GRBs
f-GRBs appear to be systematically possess low E_gamma but much larger energy in the afterglow
The gamma-ray energy release in GRB is small compared to that inferred for low-Gamma ejecta (from radio observations)
The gamma-ray energy release of GRB is only 1% of that inferred from radio observations
 The energy in relativistic ejecta can vary enormously.
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24. In Summary : c-GRBs, s-GRBs and f-GRBs
A very small fraction (1%) of the local Ib/Ic SNe can be expected to host c-GRBs.
f-GRBs (fast fading afterglows) may constitute a significant
fraction of c-GRBs
“s-GRBs” (GRB /1998bw) are arguably a new of Ib/Ic SNe. However, our VLA search for s-GRBs show that these objects are rare, <10% (Berger et al. 2003)
The primary parameter differentiating c-GRGBs, f-GRBs and s-GRBs is the amount of ejecta with large Lorentz factor (relativistic ejecta).
The sum total of local c-GRBs, s-GRBs and f-GRBs is less than 10% of the local Ib/Ic sample (Berger et al.)
(Norris 2003 estimate appears too optimistic)
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25. The story is just beginning …..
X-ray Flashes
Short hard bursts
SWIFT is expected to be launched in December 2003
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27. Backup Slides
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28. Underlying Supernovae
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Indepth discussion by J. Bloom and T. Matheson

29. Wind or ISM?
In most afterglows no CLEAR signature for a wind circumstellar medium
Clear case for GRB (Price et al. 2002)
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30. External Shocks – Afterglows
Sari, Piran, & Narayan 1998
Berger et al. 2000
GRB C
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32. Major Clue: Circumstellar Medium
Density ~ r0 (“Interstellar Medium”)
Expected if GRBs result from coalescence
Density ~ r-2 (“Wind Medium”)
Expected if GRBs arise result from massive stars
 Chevalier and Frail talk
Note: For GRBs, length ~ 2 * c * t * gamma* gamma .
In contrast, for SNRs, length ~ v * t ~ 0.03 * c * t
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33. Diversity in Cosmological High Energy Transients
Gamma-ray bursts (GRB)
-- peak luminosity in the range 50 to 500 keV
-- Short duration (T < 1 second)
-- Long Duration (T > a few seconds)
X-ray Flashes (XRF)
-- peak luminosity in the range below 50 keV
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