1. New Views of Compact Object Mergers Via Short Gamma-Ray Bursts Derek B. Fox Astronomy & Astrophysics Penn State University New Views of the Universe – KICP December 11, 2005

2. Four Afterglows: 050509B: Swift BAT+XRT 050709: HETE, Chandra, Ground, HST 050724: Swift BAT+XRT, Ground, VLA, Chandra 050813: Swift BAT+XRT Nature - 6 Oct 2005

3. Four Afterglows: 050509B: Swift BAT+XRT 050709: HETE, Chandra, Ground, HST 050724: Swift BAT+XRT, Ground, VLA, Chandra 050813: Swift BAT+XRT 5 +051210 – Swift BAT+XRT+… Nature - 6 Oct 2005

4. Eichler, Livio, Piran & Schramm 1991: Well-known GW wave source Known GRB model, but: –Short bursts –Featureless spectra R-process elements Associated neutrino burst

5. Short Bursts as Compact Object Mergers

6. Evidence for mergers Circumstantial: Old stellar populations No associated supernovae Energetics –100x less than long burst / collapsar (but see: 050813) –1000x greater than the magnetar giant flare (27 Dec 2004) –Afterglow energy comparable –Okay for NS-NS, NS-BH And possibly: Offsets from host galaxies Very old population GRB 050509B (HST)

7. Evidence for mergers Circumstantial: Old stellar populations No associated supernovae Energetics –100x less than long burst / collapsar (but see: 050813) –1000x greater than the magnetar giant flare (27 Dec 2004) –Afterglow energy comparable –Okay for NS-NS, NS-BH And possibly: Offsets from host galaxies Very old population GRB 050509B (HST)

8. Kulkarni et al. 2005 GRB 050509B: Keck/Subaru Error radius = 9.3 arcsec

9. GRB 050509B: HST Imaging Host galaxy: Giant elliptical (one of 2 cD galaxies in cluster) Member of z=0.225 cluster L = 1.5 L* SFR < 0.1 M  yr -1 GRB 050509B (HST)

10. GRB 050509B Host Galaxy Bloom et al. 2005 z=0.225 SFR < 0.1 M  yr -1

11. Berger et al. 2005 GRB 050724: Radio, NIR, Chandra

12. Kulkarni & Cameron Red elliptical z=0.258 L=1.6 L * SFR<0.03 M  yr -1

13. GRB 050724: Gemini Spectra Berger et al. 2005 z=0.257

14. GRB 050813 Host Cluster Error circle is original XRT localization

15. GRB 050813 Imaging XRT 10” B C Galaxies “B” and “C” are at z=0.72 (Prochaska et al. 2005) BUT! Galaxy cluster in vicinity has z~1.8 (Gladders et al., in prep.) One likely cluster member is found in XRT circle No spectra as yet

16. GRB 051210 Host Cluster (?) During meeting! APM cluster at ~8’ distance (Berger & Fox, GCN 4316) z~0.114 (Dalton et al. 1997) Optical/radio searches ongoing Cluster X-ray BAT

17. Evidence for mergers Circumstantial: Old stellar populations No associated supernovae Energetics –100x less than long burst / collapsar (but see: 050813) –1000x greater than the magnetar giant flare (27 Dec 2004) –Afterglow energy comparable –Okay for NS-NS, NS-BH And possibly: Offsets from host galaxies Very old population GRB 050509B (HST)

18. GRB 050709: HST Movie Fox et al. 2005 4 epochs 6-35 days F814W Exp=6360 s Blue dwarf irregular galaxy z=0.16 L=0.1 L * SFR > 0.2 M  yr -1

19. Fox et al. 2005 & Hjorth et al. 2005b No SN / 050709

20. Hjorth et al. 2005a (Ground) Kulkarni et al. 2005 (HST) I AB > 27.7 mag No SN / 050509B HST

21. Evidence for mergers Circumstantial: Old stellar populations No associated supernovae Energetics –100x less than long burst / collapsar (but see: 050813) –1000x greater than the magnetar giant flare (27 Dec 2004) –Afterglow energy comparable –Okay for NS-NS, NS-BH And possibly: Offsets from host galaxies Very old population GRB 050509B (HST)

22. Adapted from Fox et al. 2005

23. Evidence for mergers Circumstantial: Old stellar populations No associated supernovae Energetics –100x less than long burst / collapsar (but see: 050813) –1000x greater than the magnetar giant flare (27 Dec 2004) –Afterglow energy comparable –Okay for NS-NS, NS-BH And possibly: Offsets from host galaxies Very old population GRB 050509B (HST)

24. Merger alternatives Collapsar and All-Magnetar models are in trouble. What about: Multiple source populations –Generic product of BH+Disk –Magnetars present at some level –GRB 050709 in a blue dwarf star- forming galaxy Varieties of compact-object merger –NS-NS vs. NS-BH –BH-BH (Blandford) New ideas –Accretion-Induced collapse of NS to BH (MacFadyen, Ramirez-Ruiz & Zhang 2005) – accomodates 100-s long X-ray flares MacFadyen et al. 2005

25. From Bursts to Rates Nakar, Gal-Yam & Fox astro-ph/0511254 Guetta & Piran astro-ph/0511239

26. Limiting distances for LIGO K.Thorne / NSF Review

27. Binary NS Lifetimes 8 relativistic pulsar binary systems 2 discovered since 2003: –PSR J0737-3039A @ 87 Myr –PSR J1906+0746 @ ~300 Myr Merger rate dominated by short-lived systems Lifetime distribution like  –1 (flat in log-space) Champion et al. 2004 + PSR J1906+0746 1/H 0

28. Binary NS Lifetimes Kalogera et al. 2004: Minimal rate is 7 LIGO-I events kyr –1 Maximal rate is very sensitive to new discoveries (e.g. PSR J1906+0746) Estimated range: 7 to 122 kyr –1 (95% c.l.) Max. one event per 8 years for LIGO-I Kalogera et al. 2004

29. SHB Rates & Lifetimes Start with: –Cosmic SFR(z) –BATSE catalog of burst fluences –Guesses at luminosity and lifetime distributions Add: 1. SHB redshifts (Swift, HETE, IPN) 2. Or matched SHB redshifts + luminosities at a fixed threshold (Swift) 3. Estimate of burst beaming Guetta & Piran 2005

30. BATSE SHB Fluences Guetta & Piran 2005

31. SHBs Old and New Old error boxes: 1 cluster (z=0.09), one bright galaxy (z=0.14), and two empty error boxes (z>0.25) – Gal-Yam et al. 2005

32. Fox et al. 2005 & Hjorth et al. 2005b Jet Break / 050709 30:1 beaming

33. Progenitor lifetimes Begin with star-formation rate SFR(z) Single power-law luminosity function allows use of all redshifts Test various progenitor lifetime distributions  ~ 6 Gyr for narrow log- normal distributions Inconsistent with  –1 distribution (red line) Nakar, Gal-Yam & Fox 2005

34. Progenitor lifetimes Begin with star-formation rate SFR(z) Single power-law luminosity function allows use of all redshifts Test various progenitor lifetime distributions  ~ 6 Gyr for narrow log- normal distributions Inconsistent with  –1 distribution (red line) Guetta & Piran 2005

35. Lifetimes & Luminosities Nakar, Gal-Yam & Fox 2005

36. Lifetimes & Luminosities Nakar, Gal-Yam & Fox 2005

37. Lifetimes & Luminosities Nakar, Gal-Yam & Fox 2005 z=0.72 -> 1.8 z=0.114

38. Lifetimes & Luminosities Nakar, Gal-Yam & Fox 2005 z=0.72 -> 1.8 z=0.114

39. GRB 050709 SHBs and LIGO Long progenitor lifetimes and a high local rate R ≈ 10 Gpc -3 yr -1 for NS-NS with no beaming and no extrapolation to lower fluxes R > 300 Gpc -3 yr -1 with 30:1 beaming At limit of 10 47 erg s -1 (Tanvir et al. 2005): R=10 5 Gpc -3 yr -1 Max. 3 LIGO-I events yr –1 ; 0.3 yr –1 more likely Compare: 0.007–0.122 yr –1 from pulsars NS-BH or BH-BH models result in even higher rates

40. New Views of Compact Object Mergers

41. Do compact object mergers produce a strong EM signal? What is the local rate? –GW detection: LIGO, Virgo… –r-process elements Where & when are they happening? –Host types & host offsets –Progenitor lifetimes & systemic velocities Are the explosions beamed? Do they expel significant quantities of nucleon-rich ejecta? –X-ray flaring –SN-like signal Nakar, Gal-Yam & Fox 2005

42. Nakar, Gal-Yam & Fox 2005 Do compact object mergers produce a strong EM signal? What is the local rate? –GW detection: LIGO, Virgo… –r-process elements Where & when are they happening? –Host types & host offsets –Progenitor lifetimes & systemic velocities Are the explosions beamed? Do they expel significant quantities of nucleon-rich ejecta? –X-ray flaring –SN-like signal New Views of Compact Object Mergers Short bursts  LIGO-I detections feasible Majority elliptical + clusters  > 3 Gyr 1/f b ~ 30 ? Theory still young (Kulkarni 2005)

43. New Views of Compact Object Mergers Progress will require: More Swift redshifts, host galaxies, host clusters More beaming constraints Evaluation of Swift BAT thresholds or: LIGO-I Science Run 5 – in progress Nakar, Gal-Yam & Fox 2005

44. Collaborators Caltech-NRAO GRB Collaboration –S.R. Kulkarni, S.B. Cenko, A.M. Soderberg, P.B. Cameron, A. Gal-Yam, E. Nakar, D.-S. Moon, M.M. Kasliwal, F.A. Harrison at Caltech –D.A. Frail (NRAO), P.A. Price (UH IfA), T. Piran (Hebrew U.), B. Schmidt (ANU), B. Penprase (Pomona), H.-S. Park (LLNL) Carnegie Observatories –E. Berger, M. Gladders, E. Persson Swift Team –Penn State: J. Racusin, D.N. Burrows, J. Nousek, P. Mészáros, L. Gou –GSFC: C. Markwardt, T. Sakamoto –UCL: A. Blustin, M. Page SHBs with HST –P. Kumar (UT), A. Panaitescu (LANL), R. Chevalier (UVA), A. MacFadyen (IAS)

45. & Coauthors M. Roth, Carnegie D. J. Sand, Caltech S. Shectman, Carnegie M. Takada, Tohuku U. T. Totani, Kyoto U. W. T. Vestrand, LANL D. Watson, Copenhagen R. White, LANL P. Wozniak, LANL J. Wren, LANL B. L. Lee, U. Toronto P. J. McCarthy, Carnegie D. C. Murphy, Carnegie S. E. Persson, Carnegie B. A. Peterson, ANU M. M. Phillips, Carnegie J. Rich, ANU M. Rauch, Carnegie K. Roth, Gemini Obs K. Aoki, NAOJ L. L. Cowie, UH IfA A. Dey, NOAO S. Evans, LANL H. Furusawa, TIT K. C. Hurley, Berkeley N. Kawai, TIT G. Kosugi, NAOJ W. Krzeminski, Carnegie D. C. Leonard, Caltech

46. The End