Short Bursts Daniel Perley Astro November 2005

Title Subject Daniel Perley9 November 2005 Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions PBHflaremergercollapsar >10 50 >10 50 pcMpcGpcGpc too shortOKOKtoo long? invisibleyoung NSold NSyoung star nearbygalactic star-forming galaxiesoutskirtsregions repeats?possibleIb/c supernova mini-SN

Long Bursts GRB Classes Daniel Perley9 November 2005 Short Bursts GRBs have long been known to fall into two general categories: time (seconds) count rate (ct/s) 45 s l o n g b u r s t Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Short Bursts GRB Classes Daniel Perley9 November 2005 time (seconds) count rate (ct/s) short burst 0.8 s GRBs have long been known to fall into two general categories: Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Burst Durations GRB Classes Daniel Perley9 November 2005 T 90 (seconds) N The separate populations are statsitcally robust, although intersecting Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Burst Durations GRB Classes Daniel Perley9 November 2005 T 90 (seconds) N The separate populations are statsitcally robust, although intersecting. short bursts l o n g b u r s t s Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Duration/Hardness GRB Classes Daniel Perley9 November 2005 T 90 (seconds) The two populations have different hardnesses: Hardness (S 3 /S 2 ) short bursts l o n g b u r s t s Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Duration/Fluence GRB Classes Daniel Perley9 November 2005 Other intrinsic differences have also been noticed. T 90 (seconds) F tot (erg/cm 2 ) Figure 1, Balasz et al l o n g b u r s t s short bursts Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Long Burst Localization Daniel Perley9 November 2005 First GRB (long burst) localized and first host identified in Many have followed since then. All long GRBs located in star-forming galaxies All long GRBs located in regions with massive stars Coincident type Ic supernova observed in one case → Long bursts are associated with supernovae. However, short GRBs long eluded localization, and no similar conclusions could be made. Short Bursts Before Swift Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Short Burst Localization Daniel Perley9 November 2005 The intrinsically short duration of a short burst makes determining the position of the prompt gamma emission even more difficult than usual. "Best" localizations (5-50 square arcmin) generally from Interplanetary Network. Short Bursts 5 ' Before Swift Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Afterglow Nondetections Before Swift Daniel Perley9 November 2005 Before thist year, no short burst afterglow had been found in any IPN or burst detection error box. Short Bursts 1 = arcmin 2 2 = B 24.5 arcmin 2 3 = arcmin 2 4 = arcmin 2 = long burst detected = long burst limit Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Galaxy Correlations Before Swift Daniel Perley9 November 2005 (Recent) study computes correlation function of BATSE short burst positions with nearby galaxies. Short Bursts Result: correlation significant to 2σ No correlation seen for long bursts. Estimate of 5-25% of GRBs from <100 Mpc Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Burst Models Daniel Perley9 November 2005 A large number of models had been proposed – mostly of the same which had been previously proposed for GRBs in general. Black hole evaporation SGR (magnetar) giant flares Neutron star – neutron star mergers Neutron star – black hole mergers Collapsar Neutron star collapse (supranova) Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Primordial Black Holes Burst Models Daniel Perley9 November 2005 An early suggestion: GRBs may be the evaporation of black holes produced in the early universe. T 90 (seconds) N Mass: 7 × g (mc 2 = 5 × erg) → Distance: ~few parsecs Burst duration: < ms cannot explain most short bursts Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Magnetar Giant Flare Burst Models Daniel Perley9 November 2005 Massive flare on the surface of highly magnetized neutron star. Catastrophic magnetic field reorganization. Some previous flares: - 5 March 1979 event: 4 × ergs (SGR , LMC) 0.2 s - 27 August 1998 event: 8 × ergs (SGR ) 0.2 s Duration and hardness consistent with short GRBs. Distance for GRB: 4 Mpc (Virgo cluster: 20 Mpc) But could there be much larger flares? Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Magnetar Giant Flare Burst Models Daniel Perley9 November March 1979 event: 4 × ergs (SGR , LMC) 0.2 s - 27 August 1998 event: 8 × ergs (SGR ) 0.2 s - 27 December 2004 event 2 × ergs (SGR ) 0.5 s 0.8 erg/cm 2 over 0.5s Most energetic Galactic event since Tycho. Sirius: erg/cm 2 /s Full Moon: 1 erg/cm 2 /s Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Magnetar Giant Flare Burst Models Daniel Perley9 November March 1979 event: 4 × ergs (SGR , LMC) 0.2 s - 27 August 1998 event: 8 × ergs (SGR ) 0.2 s - 27 December 2004 event 2 × ergs (SGR ) 0.5 s Duration and hardness consistent with short GRBs. (long ringing 'tail' would not be detectable at great distance) Distance for GRB: 30 Mpc (Virgo cluster: 20 Mpc) Magnetars all young: ~10 4 year lifetime (restricted to star-forming galaxies/regions) Repetition possible over long time scales Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Neutron Star-Neutron Star Merger Burst Models Daniel Perley9 November 2005 Gravitational binding energy: ~ erg → Mpc/Gpc distances Timescale for collapse: <~1 second Closely orbiting neutron stars (d ~< solar radius) lose energy from gravitational radiation. Systems known to exist (binary pulsars) Must eventually merge. Post-merger object quickly collapses to black hole Very high angular momentum of system : accretion disk forms; falls onto black hole. Short Bursts G M 2 R Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Neutron Star-Black Hole Merger Burst Models Daniel Perley9 November 2005 Gravitational binding energy: M NS c 2 ~ erg → Mpc/Gpc distances Timescale for accretion: <~1 second Closely orbiting neutron star / black hole pair also loses energy to gravitational radiation and merges. Neutron star is tidally disrupted into accretion disk; falls onto black hole. Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions Supernovae can 'kick' binary out of Galaxy.

Compact Object Mergers Burst Models Daniel Perley9 November 2005 Either type of merger: Inspiral takes ~ 1 Gyr. Star formation may have ceased. System may have migrated from point of origin – supernova explosions can kick the binary well outside galactic interior Possibility of "mini-supernova" due to production of radioactive elements in ejected matter. Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Collapsar Burst Models Daniel Perley9 November 2005 Collapsar (hypernova) model highly successful in describing long bursts. Collapse of iron core of highly massive star to black hole + accretion of material (0.1-5 M sun ). Relativistic jet penetrates stellar envelope Energies ~ erg : cosmological distances Fallback time for stellar core: ~few seconds too slow for short GRBs. Significant uncertanties in calculation; Breakout flash could be shorter? Massive stars short-lived: would be bound to star-forming regions (like long GRBs) Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Model Summary Burst Models Daniel Perley9 November 2005 PBHgiant flaremergercollapsar Energy (erg) ~10 50 >10 50 Distance scale pcMpcGpc Timescale too short OK too long? Progenitor mini-BHyoung NSold NS binary short-lived star Environment Galaxystar-forming galaxies in/near all types of galaxies star-forming galaxies Signatures possibility of repeat possible mini-SN type Ib/Ic supernova Short Bursts Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

GRB B The Swift Era Daniel Perley9 November 2005 Short Bursts First Swift short burst. First X-ray afterglow: XRT provided 2.8' localization This position is very close to large elliptical at center of low-z cluster. XRT Large elliptical z = blue T 90 = S = 1 × E = 3 × Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions all units CGS

GRB B The Swift Era Daniel Perley9 November 2005 Short Bursts Is the burst associated with the elliptical? Chance alignment probability very small. inside galaxy cluster: 3% within 45" of center: 0.07% (no long GRB ever seen in a cluster) XRT Large elliptical z = blue 40 kpc T 90 = S = 1 × E = 3 × Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

GRB B The Swift Era Daniel Perley9 November 2005 Short Bursts Is the burst associated with the elliptical? Chance alignment probability very small. inside galaxy cluster: 3% within 45" of center: 0.07% (no long GRB ever seen in a cluster) T 90 = S = 1 × E = 3 × Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions Additional arguments: Extremely short duration even for short GRBs – putting at high redshift (z~2) requires unrealistically short intrinsic duration. Energetics of putting at high-z similarly difficult for very short durations.

GRB B The Swift Era Daniel Perley9 November 2005 Short Bursts No counterpart seen at other wavelengths. Cannot be a supernova (if in cluster). No mini-supernova observed. T 90 = S = 1 × E = 3 × Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions SNIa peak

GRB The Swift Era Daniel Perley9 November 2005 Short Bursts HETE-II short burst. X-ray afterglow seen. Unambiguously in low-z galaxy. Optical transient (first ever for short GRB) detected coincident with X-ray position. XRT HST Transient Star-forming irregular z = kpc T 90 = S = 3 × E = 2 × Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

GRB The Swift Era Daniel Perley9 November 2005 Short Bursts Optical light curve: power-law decay with jet break (like long burst – no supernova bump) T 90 = S = 3 × E = 2 × Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions X-ray Optical Radio

GRB The Swift Era Daniel Perley9 November 2005 Short Bursts Optical and radio (first for short GRB) transients seen. Unambiguously associated with non star-forming galaxy (within last Gyr) at low-z. Not in a cluster. Transient Early-type z = XRT 2.6 kpc T 90 = 3 S = 6 × E = 1 × Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

GRB The Swift Era Daniel Perley9 November 2005 Short Bursts X-ray afterglow, but no optical/radio transient. Inside a cluster - numerous possible hosts. XRT Elliptical z = Elliptical z = 0.73 Elliptical z = T 90 = 0.6 S = 6 × E = 1 × Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

GRB The Swift Era Daniel Perley9 November 2005 Short Bursts No X-ray afterglow detected. BAT position consistent with IC 326. BATIC 326 z = IC 327 p ~ 0.1% T 90 = 3 S = 6 × E = 1 × at 133 Mpc Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

GRB The Swift Era Daniel Perley9 November 2005 Short Bursts Soft, thermal spectrum. Galactic latitude: b = - 0.1° Strong radio source – no optical or X-ray detections. SGR flare ('new' SGR) T 90 = 0.13 S = 8 × E = 1 × at 20 kpc Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

GRB The Swift Era Daniel Perley9 November 2005 Short Bursts IPN detection of bright short GRB. Consistent with outer regions of M81. M 81 Sb z = 0 M 82 Irr z = 0 p ~ 0.5% T 90 = 0.17 S = 2 × E = 5 × at 4 Mpc (M81) ~ at 500 Mpc Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

GRB A The Swift Era Daniel Perley9 November 2005 Short Bursts No X-ray afterglow detected. BAT T 90 = 0.13 S = 2 × E = ? Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

Recent Short Bursts The Swift Era Daniel Perley9 November 2005 Short Bursts redshifthost trans most likely origin B0.2248E (cl)3 × XNS-NS/BH merger Irr2 × XONS-NS/BH merger early1 × XORNS-NS/BH merger E (cl)2 × XNS-NS/BH merger ?S1 × giant flare? Galaxy ~ large SGR flare ?Sb?5 × giant flare? A?? energy (erg) Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions

The Swift Era Daniel Perley9 November 2005 Short Bursts Most short bursts are due to compact object mergers. Short bursts are beamed. Some short bursts may be due to magnetar giant flares in other galaxies, but a definitive example is still lacking. Short bursts occur more frequently per volume than long bursts (or are beamed less), but are intrinsically fainter. Classes of GRBs Long Bursts Short Bursts Durations Duration vs. Hardness Duration vs. Fluence Short Bursts before Swift Long Burst Localization Short Burst Localization Afterglow Nondetections Galaxy Correlations Short Burst Models Primordial Black Holes Magnetar Giant Flare NS-NS Merger NS-BH Merger Collapsar Summary Short Bursts since Swift GRB050509B GRB GRB GRB GRB GRB GRB GRB051105A Summary Conclusions