Gamma-ray Bursts and Supernovae S. R. Kulkarni California Institute of Technology 12:57

TWO BIG QUESTIONS Do all cosmological GRBs have an underlying SN? Do all nearby (Ib/c) supernovae have gamma-ray emission? 12:57

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 12:57

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) 12:57

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Jet Signatures: Optical/X-ray Piran, Science, 08 Feb 2002 12:57

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 12:57

Gamma-ray Energy Release Frail et al. (2001) 12:57 “Infamous” Frail et al. relation

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 12:57 Berger et al. 2003

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 980326 Bloom et al. 1999 GRB 970828 Galama et al. 2000, Reichart et al. 1999 GRB 011121 Garnavich et al. 2002, Bloom et al. 2002 GRB 021211 Della Valle et al. 2003 GRB 030329 Stanek et al. 2003 12:57

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 12:57

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… 12:57

GRB 980425 & SN 1998bw GRB 980425, 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 ~ 1048 erg (isotropic) 12:57

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 12:57

Synchrotron Emission: Fast Primer Basic Parameters: fm, num, nua, spectral index (p) Example: GRB 030329 (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) 12:57

SN 1998bw: Underlying Engine! Chevalier & Li 12:57

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 12:57

s-GRBs and c-GRBs: Cousins? 12:57 Berger et al. 2003

f-GRBs: a new sub-class of c-GRBs? Afterglow of GRB 980327 and GRB 980519 were already fading rapidly (t^-2). We term such GRBs as “f-GRBs” (for GRBs with rapidly fading afterglow) Bloom, Frail & Kulkarni 2003 12:57

GRB 030329: an f-GRB? 12:57 Price et al. (2003, submitted to Nature)

GRB 991216: 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 12:57

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 12:57

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 991216 is small compared to that inferred for low-Gamma ejecta (from radio observations) The gamma-ray energy release of GRB 980425 is only 1% of that inferred from radio observations  The energy in relativistic ejecta can vary enormously. 12:57

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 980425/1998bw) 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) 12:57

The story is just beginning ….. X-ray Flashes Short hard bursts SWIFT is expected to be launched in December 2003 12:57

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Backup Slides 12:57

Underlying Supernovae 12:57 Indepth discussion by J. Bloom and T. Matheson

Wind or ISM? In most afterglows no CLEAR signature for a wind circumstellar medium Clear case for GRB 021121 (Price et al. 2002) 12:57

External Shocks – Afterglows Sari, Piran, & Narayan 1998 Berger et al. 2000 GRB 000301C 12:57

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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 12:57

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 12:57