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The Swift Gamma-Ray Burst Explorer Paolo D’Avanzo INAF-Osservatorio Astronomico Di Brera

The Swift Gamma-Ray Burst Explorer Paolo D’Avanzo INAF-Osservatorio Astronomico Di Brera (MISTICI team) Universita` degli studi dell’Insubria. M ultiwavelength I talian Swift T eam with I nternational C o- I nvestigators. The Swift Mission.

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The Swift Gamma-Ray Burst Explorer Paolo D’Avanzo INAF-Osservatorio Astronomico Di Brera

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  1. The Swift Gamma-Ray Burst Explorer Paolo D’Avanzo INAF-Osservatorio Astronomico Di Brera (MISTICI team) Universita` degli studi dell’Insubria Multiwavelength Italian SwiftTeam with International Co-Investigators

  2. The Swift Mission • Successfully launched on the 20th of November 2004 • 267 days in orbit • All instruments operating to spec • BAT First Light: 3 December 2004 • XRT First Light: 11 December 2004 • First BAT Burst: 17 December 2004 • First XRT Afterglow: 23 December 2004 • UVOT First Light: 12 January 2005 • First UVOT Afterglow 15 March 2005 • Calibration phase ended on Apr 5

  3. OUTLINE • GRB: theory and open matters • Swift & REM: instruments, performances & science • GRB: results • Observationals procedures: BA & DS • Secondary science: X-Ray Binaries • Conclusions & Future

  4. GRB Characteristics (BATSE+SAX) • Short (10 ms < t < 1000 s) and intense (E ~ 10^54 erg) pulse of gamma rays occurring at random positions in the sky • Isotropic distribution (BATSE) • Afterglow era (SAX) • Cosmological distances (SAX)

  5. The standard model: fireball UV/opt/IR/radio gamma-ray gamma-ray X-ray UV/optical IR mm radio central photosphere internal external shocks engine (shocks) (reverse)(forward) Emission mechanism: synchrotron emission from power-law distribution electrons in highly relativistic outflows Rees & Meszaros 1994; Paczynski & Xu 1994

  6. Progenitors: long GRBs Light curves Spectra GRB 021211 (Massimo Della Valle, Daniele Malesani, Stefano Benetti, Vincenzo Testa, Mario Hamuy, L. Angelo Antonelli, Guido Chincarini, Gabriele Cocozza, Stefano Covino, Paolo D'Avanzo & 7 coautori A&A 406, L33-L37 (2003)) SN - Connection GRB 980425 (Galama et al., 1998) First GRB – SN association GRB 031203 (Daniele Malesani, Gianpiero Tagliaferri Guido Chincarini, Stefano Covino, Massimo Della Valle, Dino Fugazza, Paolo Mazzali, Filippo M. Zerbi, Paolo D'Avanzo & 17 coautori ApJ 609, L5-L8 (2004))

  7. 8 hour data gap 4 orders of magnitude The data gap Beppo-SAX takes at least 6-8 hours to perform an afterglow follow-up observation with its narrow field instruments. During this time, afterglow fades orders of magnitude. Swift was designed to fill in the gap making very early observations of the afterglows, beginning approximately a minute after the burst.

  8. UVOT BAT BAT XRT UVOT XRT Spacecraft Spacecraft Swift Mission • Burst Alert Telescope (BAT) • 15-150 keV • FOV: 2 steradiants • Centroid accuracy: 1’ - 4’ • X-Ray Telescope (XRT) • 0.2-10.0 keV • FOV: 23.6’ x 23.6’ • centroid accuracy:5” • (UVOT) UV/Optical Telescope • 30 cm telescope • 6 filters (170 nm – 600 nm) • FOV: 17’ x 17’ • 24th mag sensitivity (1000 sec) • Centroid accuracy 0.5”

  9. A fast moving telescope … • Alt-az 60 cm f/8 RC silver-coated • 2 Nasmyth foci (one idle) • 60 deg 5 sec – to any , in 60 sec • 10x10 am2 FoV • … with a high throughput NIR Camera… • 10x10 am2 FoV • 1.2 as pixel scale (diff.limited) • 0.9-2.3 microns (Z’,J,H,Ks) • 512x512 HgCdTe chip @77 Kelvin • Wobbling plate for dithering

  10. XRT Image UVOT/REM Image BAT Burst Image T<10 sec  < 4' T<100 sec  < 5'' T<300 sec T< 60 sec BAT Error Circle Observing Scenario • Burst Alert Telescope triggers on GRB, calculates position on sky to < 4 arcmin • Spacecraft autonomously slews to GRB position in 20-70 s • X-ray Telescope determines position to < 5 arcseconds • UV/Optical Telescope images field, transmits finding chart to ground

  11. BAT Bursts • 66 GRBs detected/imaged since Dec. 17 (33.5 weeks as of 08/30/05) 041217 050315050410050502B 050603 050715 050730 050815 041219A,B,C 050318050412050505 050607 050716 050803 050819 041220 050319050416A,B050507 050701 050716 050805 050820A,B 041223050326 050418 050509A,B050712 050721 050807 050822 041224 050401 050421 050525 050713A,B 050724 050813 050824 041226 050406050422 050528 050714B 050726 050814 050830 041228 050117 050124 050126 050128 050202 050215A 050215B 050219A,B 050223 050306 Average rate is ~90/year

  12. XRF Short GRB XRF XRF XRF XRF Short GRB XRF XRF Short GRB

  13. RESULTS

  14. Progenitors: short GRBs (I) GRB 050509B: first detection of the X-ray afterglow of a short GRB (N. Gehrels et al., 2005 Nature) GRB 050709: first detection of the optical afterglow of a short GRB (S. Covino, D. Malesani, G.L. Israel, P. D’Avanzo & 29 coauthors, 2005 A&AL, submitted) GRB 050724: again a detection of the optical afterglow of a short GRB (S.D. Barthelmy, G. Chincarini, D.N Burrows, N. Geherels, S. Covino, A. Moretti, P. Romano, P.T. O’Brien, C.L. Sarazin, C. Kouvelotou, M. Goad, S. Vaughan, G. Tagliaferri, B. Zhang, A. Antonelli, S. Campana, P. D’Avanzo & 12 coauthors, 2005 Nature, submitted) Host Galaxies

  15. Progenitors: short GRBs (II) GRB 050509B & GRB 050724 Host Galaxies Host Galaxies of long GRB XRT position • early type elliptical • red color spectrum • no emission lines vs. Low star formation rate Population of very old stars GRB 050709 Host Galaxy • late type irregular • blue color spectrum • Hα emission line off-core (3 kpc) position of the OT, consistent with a system of age 10^9 y BUT...

  16. The fartest GRB ever observed z = 6.3! ESO press release 12 Sep 2005

  17. Observational procedures (I) REM

  18. Observational procedures (II) • Burst Advocate • Rem Duty Scientist

  19. Science with Swift & REM GRB! GRBs observed rate now is about 2 burst per week but also latitude/longitude constraints have to be taken into account. This is leaving free Swift & REM observing time that is largely used for: Any program requesting fast multi-frequency observations • Multifrequency monitoring of AGNs • X-Ray Binaries • Flare Stars • Others...

  20. X-Ray Binaries SXRT • sporadic outbursts • long quiescent periods

  21. Doppler tomography • image reconstruction • monitoring at different orbital phases • bidimensional maps spectral lines … and corresponding velocity coordinates familiar spatial coordinates…

  22. Centaurus X-4 – quiescent optical emmission Hα HeI 5875 HeI 6678 • circular ring-like structure in • emission • emission from the companion • visible “hot spot” Irradiation hypothesis: • DISC • Hα emission from external • region • HeI emission from internal • region • COMPANION STAR • Hα emission from low • velocity regions • HeI emission from high • velocity regions

  23. Origin of the quiescent emission (I) The companion fills its Roche Lobe and could be subject to irradiation from the NS fase 0 fase 0.25 fase 0.5 fase 0.75

  24. Origin of the quiescent emission (II) EW = 4.4 ± 0.5 Å log FHα = log EW(Hα) + 0.113(B-V)2 – 1.188(B-V) +7.487 (Soderblom et al., 1993) FHα= 7 x 106 erg cm-2 s-1 LX = 4 x 1032 erg s-1 (Campana et al., 2004) FX= LX/(4πa2) = 5 x 108 erg cm-2 s-1 a = 3.6 solar radius 1% of the incident X-Ray flux should be reprocessed to Hαphotons LHα= f1f2LX = 5 x 10-3 LX = 0.5% LX f1= solid angle f2= 0. 3 (Osterbrock 1987) D'Avanzo et al. 2005, A&A, accepted

  25. ms X-Ray Pulsars Campana, D'Avanzo et al., 2004, ApJ TNG approved proposal (P.I.: P. D’Avanzo) ESO – VLT proposal (in prep.)

  26. Conclusions (I) • Exciting Swift results on: • GRB progenitors • Host Galaxy morfology • High z GRB • New light on quiescent optical emission of SXRTs • Opportunity to investigate the link between ms X-Ray Pulsars and ms Radio Pulsars

  27. Conclusions (II) • Our results on GRB led to: • 42 GCN circulars • 3 published papers • 3 submitted papers • 2 papers in preparation • Our results on SXRT led to: • 1 paper published • 1 approved TNG proposal • 3 ESO proposals in preparation

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