Swift Nanjing GRB Conference Prompt Emission Properties of X-ray Flashes and Gamma-ray Bursts T. Sakamoto (CRESST/UMBC/GSFC)

Swift Nanjing GRB Conference Contents 1.First BAT GRB catalog 2.X-ray Flashes (XRFs) 3.Prompt emission properties of XRFs (BATSE/BeppoSAX/HETE-2/Swift)? (4. X-ray flares) (5. X-ray afterglows of XRFs)

Swift Nanjing GRB Conference First BAT GRB catalog (BAT1 catalog) Sakamoto et al. ApJS, 175, 179

Swift Nanjing GRB Conference BAT GRB sky map BAT GRB sky map GRBs (from GRB to GRB ) - BAT event-by-event data analysis Galactic coordinate

Swift Nanjing GRB Conference T 90 /T 50 (mask-weighted keV)

Swift Nanjing GRB Conference Hardness – T 90

Swift Nanjing GRB Conference Time-averaged spectrum (PL fit)

Swift Nanjing GRB Conference PL photon index vs. P( keV)

Swift Nanjing GRB Conference Summary (I) BAT is fine. Detecting/localizing ~100 GRBs/yr. Watching for z>7 and z<0.1 GRBs. Watching for the next naked eye burst.

Swift Nanjing GRB Conference X-ray Flashes (XRFs)

Swift Nanjing GRB Conference X-ray band  ray band X-ray flash (XRF) Classical gamma-ray burst (C-GRB) (Heise et al. 2001) (in’t Zand et al. 1999) X-ray flashes and classical (long) GRBs : BeppoSAX/BATSE

Swift Nanjing GRB Conference XRF GRB X-ray flashes and classical (long) GRBs : HETE-2

Swift Nanjing GRB Conference GRB XRF A X-ray flashes and classical (long) GRBs: Swift BAT

Swift Nanjing GRB Conference “X-ray Flashes”

Swift Nanjing GRB Conference Empirical spectral models of GRBs E  exp (  E/E 0 ) EE E 0 = E peak / (2 +  ) E break = (  E 0 Band function dN/dE Energy (Band et al. 1993)

Swift Nanjing GRB Conference Spectral parameters of GRBs (BATSE) Band function  EpEp  3  2  log E p [keV] (  ~  2.5) (BATSE spectral catalog, Preece et at. 2000) Energy F E EpEp E  200 – 300 keV

Swift Nanjing GRB Conference X-Ray Flashes (XRFs) and X-ray rich GRBs (Ginga and BeppoSAX WFC) Ginga (Strohmayer et al. 1998)   log E p [keV] Number of events BATSE WFC / BATSE (Kippen et al. 2002) (22 GRBs) E p (keV) Peak Flux P 1024 (ph cm -2 s -1 ) XRFs: Systematically low E peak

Swift Nanjing GRB Conference Prompt emission properties of XRFs

Swift Nanjing GRB ConferenceObjective GRBs Classify XRFsXRRsC-GRBs (X-ray flashes) (X-ray-rich GRBs) (Classical GRBs) Spectral hardness XRFs XRRs C-GRBs XRFs XRRs C-GRBs

Swift Nanjing GRB Conference Classification of GRBs (Fluence in 2-30 keV : S X, Fluence in keV : S   log (S X / S  ) > 0  0.5 < log (S X / S  ) ≤ 0 log (S X / S  ) ≤  0.5 XRF XRR C-GRB (Sakamoto et al. 2005) HETE-2 BeppoSAX “XRFs: Detected by Wide Field Camera (WFC), but not by Gamma-Ray Burst Monitor (GRBM)” Swift/BAT ?

Swift Nanjing GRB Conference E peak vs. fluence ratio E peak (keV) S X / S  XRF XRR C-GRB HETE GRB sample

Swift Nanjing GRB Conference Classification of GRBs (Fluence in 2-30 keV : S X, Fluence in keV : S   log (S X / S  ) > 0  0.5 < log (S X / S  ) ≤ 0 log (S X / S  ) ≤  0.5 XRF XRR C-GRB (Sakamoto et al. 2005) HETE-2 BeppoSAX “XRFs: Detected by Wide Field Camera (WFC), but not by Gamma-ray burst monitor (GRBM)” Swift/BAT  Ep=30 keV  Ep=100 keV (Sakamoto et al. 2008)

Swift Nanjing GRB Conference GRB sample BATSE (Kaneko et al. 2006) - Time-averaged best fit spectral parameters by BAND and COMP fit 0 XRF 181 GRB 26 XRR 155 C-GRB Total 568 GRBs (342 GRBs) BeppoSAX (D’Alessio et al. 2006, Amati et al. 2002) - Only  Ep information 7 XRF 24 GRB 11 XRR 6 C-GRB HETE-2 (Sakamoto et al. 2005; Pelangeon et al. submitted A&A) 26 XRF 84 GRB 33 XRR 25 C-GRB Swift/BAT (Sakamoto et al ); 17 XRF 279 GRB 179 XRR 83 C-GRB Swift/BAT with Ep (Sakamoto et al ); 17 XRF 53 GRB 22 XRR 14 C-GRB

Swift Nanjing GRB Conference List of XRFs I (BeppoSAX/HETE-2/Swift) XRF Mission E peak obs [keV] AG z SAX 19 +/ SAX 26 +/- 3 X SAX 15 +/ SAX 9 (-7/+50) X SAX 38 +/ SAX 1.6 +/ HETE HETE-2 32 (+27/-9) HETE-2 19 (+18/-9) HETE-2 < HETE-2 NA HETE-2 28 (+13/-7) SAX 3 +/- 3 X HETE-2 9 (+5/-3) HETE-2 3 +/- 1 O,R HETE-2 15 (+14/-7) HETE-2 28 (+17/-8) - - XRF Mission E peak obs [keV] AG z HETE-2 3 (+1/-2) HETE-2 35 (+12/-8) O HETE /- 5 X,O HETE-2 < 8.9 X,O HETE-2 27 (+7/-5) HETE (+2/-4) B HETE-2 38 (+28/-12) B HETE-2 6 (+4/-5) HETE-2 30 (+5/-4) HETE-2 < 3.4 X B HETE-2 25 (+16/-8) A HETE-2 14 (+3/-4) B HETE-2 17 (+13/-13) X HETE-2 < 3.5 O Swift 29 (+7/-12) X,O HETE-2 26 (+11/-7) X,O A Swift 17 (+6/-10) X,O,R

Swift Nanjing GRB Conference List of XRFs II (BeppoSAX/HETE-2/Swift) XRF Mission E peak obs [keV] AG z HETE-2 < B Swift 27 (+7/-18) X Swift 22 (+6/-17) X Swift < 19 X,O Swift 4.7 (-0.3/+0.4) X,O,R Swift < 33 X B Swift 23 (+5/-12) X,O Swift 23 (+8/-18) X,O B Swift < 27.6 X Swift < 23 X,O Swift 19 (+11/-8) Swift < 35 X,O A Swift < 20 X A Swift < 30 X,O B Swift 20 (+5/-6) Swift < 24 X,O Swift 24 (+5/-5) X,O - Total: 51 XRFs XA : 24 XRFs OA : 17 XRFs z : 11 XRFs

Swift Nanjing GRB Conference Histogram of log[S(2-30 keV)/S( keV)] C-GRBs XRRXRF

Swift Nanjing GRB Conference Histogram of S(25-50 keV)/S( keV) C-GRBs XRRXRF Broad continuum in the fluence distribution

Swift Nanjing GRB Conference S(2-30 keV) vs. S( keV) C-GRBs/XRR XRR/XRF

Swift Nanjing GRB Conference S(2-30 keV) vs. S( keV) C-GRBs/XRR XRR/XRF

Swift Nanjing GRB Conference S(25-50 keV) vs. S( keV) C-GRBs/XRR XRR/XRF

Swift Nanjing GRB Conference S(25-50 keV) vs. S( keV) C-GRBs/XRR XRR/XRF

Swift Nanjing GRB Conference S(25-50 keV) vs. S( keV) C-GRBs/XRR XRR/XRF Single distribution in the fluence-fluence plane

Swift Nanjing GRB Conference Histogram of E peak obs Broad E peak obs distribution (from a few keV to a few MeV)

Swift Nanjing GRB Conference E peak obs vs. alpha

Swift Nanjing GRB Conference E peak obs vs. alpha

Swift Nanjing GRB Conference E peak obs vs. alpha

Swift Nanjing GRB Conference E peak obs vs. alpha alpha ~ -1 for all GRBs

Swift Nanjing GRB Conference E peak obs vs. beta

Swift Nanjing GRB Conference E peak obs vs. beta

Swift Nanjing GRB Conference E peak obs vs. beta

Swift Nanjing GRB Conference E peak obs vs. beta beta ~ -2.5 for all GRBs

Swift Nanjing GRB Conference E peak obs vs. S(2-400 keV)

Swift Nanjing GRB Conference E peak obs vs. S(2-400 keV)

Swift Nanjing GRB Conference E peak obs vs. S( keV)

Swift Nanjing GRB Conference E peak obs vs. S( keV)

Swift Nanjing GRB Conference E peak obs vs. S( keV) Positive correlation between E peak obs and the fluence E peak obs ~ S 0.5

Swift Nanjing GRB Conference Redshift distributions

Swift Nanjing GRB Conference E peak src distribution Broad E peak src distribution

Swift Nanjing GRB Conference E peak -E iso relation E peak src = 95 keV (E iso /10 52 ergs) 0.5 (Amati 2006)

Swift Nanjing GRB Conference Re-classify XRFs at the rest frame XRF z E peak obs E peak src Re-classification XRF C-GRBs XRR B XRR XRR A XRF <19 <34 XRF/XRR XRF XRR <23 <97 XRR <24 <60 XRR Only three XRFs cab be classified as XRF at the rest frame.

Swift Nanjing GRB Conference Summary (II) XRFs, XRRs, and GRBs form a continuum (BATSE/BeppoSAX/HETE-2/Swift). E peak obs is broadly distributed from a few keV to a few MeV (same for E peak src ). The redshift distribution of XRFs could be systematically lower than C-GRBs. We only have three samples of intrinsic XRFs. C-GRB XRR XRF E -1 E- 2.5 E peak

Swift Nanjing GRB Conference X-ray Flares

Swift Nanjing GRB Conference X-ray Flare: Prompt X-ray emission GRB (Metzger et al, 1974) (Apollo 16 and Vela 6A) GRB

Swift Nanjing GRB Conference GRB X-ray flare Counts/sec/det Counts/sec Counts/sec/wire

Swift Nanjing GRB Conference Late-time X-ray flares are unique… (Watson et al. 2005) X-ray flares T 0 > 1000 s Very unique Swift/XRT observations However… X-ray flares T 0 < 1000 s Same prompt X-ray emission observed by previous missions (e.g. HETE-2/WXM) GRB

Swift Nanjing GRB Conference X-ray afterglows of XRFs (Sakamoto et al. 2008, ApJ, 679, 570)

Swift Nanjing GRB Conference XRF X-ray afterglow

Swift Nanjing GRB Conference C-GRB X-ray afterglow

Swift Nanjing GRB Conference X-ray light curve at the rest-frame E peak src < 100 keV 100 keV < E peak src < 300 keV E peak src > 300 keV

Swift Nanjing GRB Conference FxFx Time [s] t –0.5 – t –1.0 t -1.0 – t-2.0 t -1 C-GRB XRF sec C-GRB: Break around sec XRF: Simple decay with the index of -1 Flux is systematically lower Must be telling something…

Swift Nanjing GRB Conference Summary (III) XRFs, XRRs, and GRBs form a continuum (BATSE/BeppoSAX/HETE-2/Swift). E peak obs is broadly distributed from a few keV to a few MeV (same for E peak src ). The redshift distribution of XRFs could be systematically lower than C-GRBs. We only have three samples of intrinsic XRFs. Clear definition in “X-ray flare” is needed. Distinct difference in X-ray afterglows between XRFs and C-GRBs.

Swift Nanjing GRB Conference

Swift Nanjing GRB Conference

Swift Nanjing GRB Conference E peak vs. Energy Flux Number of simulated spectra      Band –    PL ) > 6 BAT keV E peak measurement with BAT: > ~ 2 x ergs/cm 2 /s (log F(15-150) = -7.7)

Swift Nanjing GRB Conference E peak -Gamma relation

Swift Nanjing GRB Conference E peak -Gamma relation

Swift Nanjing GRB Conference BAT (81 GRBs) BATSE BAT T 90 vs. Hardness

Swift Nanjing GRB Conference GRB GRB Sakamoto et al. Villasenor et al. HETE (46 GRBs) BATSE HETE T 90 vs. Hardness

Swift Nanjing GRB Conference Konus-Wind T 90 vs. Hardness Mazets et al. : short GRBs V. Pal’shin : long GRBs Konus-Wind (125 GRBs) BATSE

Swift Nanjing GRB Conference Konus-Wind Histograms of Hardness long GRBs (T 90  2 sec.) Short GRBs (T 90 < 2 sec.) HR ≧ 6: 10% short GRBs (46% BATSE) HR ≧ 8: 0% short GRBs (26% BATSE) S( keV) / S( keV) Number of GRBs

Swift Nanjing GRB Conference Histogram of Hardness - Short GRBs - S( keV) / S( keV) Number of GRBs BAT HETE BATSE Konus-Wind

Swift Nanjing GRB Conference  vs. E 0  vs. E 0  E 0 [keV] Hardness = S( keV) S( keV)

Swift Nanjing GRB Conference S(2-30 keV) vs. S( keV)

Swift Nanjing GRB Conference “Short XRFs” in the Swift sample?

Swift Nanjing GRB Conference “Short XRFs” in the Swift sample?

Swift Nanjing GRB Conference “Short XRFs” in the Swift sample?

Swift Nanjing GRB Conference “Short XRFs” in the Swift sample?

Swift Nanjing GRB Conference How to make short XRF with BAT? dN/dE E E -1 E -2.3 Ep Flux ( keV) Input light curve Ep = 50 keV Ep = 30 keV Ep = 20 keV Count rate [c/s] - BAT energy response (30 deg) - background included - Xspec fakeit “Shortness” of BAT XRF is very likely due to the instrumental effect.

Swift Nanjing GRB Conference XRF XRR C-GRB Energy spectrum of XRFs Energy (keV)  2 10  4 F  (keV cm  2 s  1 )

Swift Nanjing GRB Conference Discussion (1) Two categories in the luminosity evolution in the optical light curves (Liang & Zhang). = 96 keV for the dim group = 543 keV for the bright group (ref Amati 2006) Consistent with the X-ray luminosity light curves Understanding Shallow-to-normal break in the geometrical jet model.

Swift Nanjing GRB Conference Discussion (2) Shallow-to-normal break E peak Thick ring jet model