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Masanori Ohno (ISAS/JAXA). HXD: 10-600 keV WAM: 50keV-5MeV XIS: 0.2-12keV X-ray Afterglow (XIS + HXD withToO) Wide energy band (0.2-600 keV) Ultra-low.

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Presentation on theme: "Masanori Ohno (ISAS/JAXA). HXD: 10-600 keV WAM: 50keV-5MeV XIS: 0.2-12keV X-ray Afterglow (XIS + HXD withToO) Wide energy band (0.2-600 keV) Ultra-low."— Presentation transcript:

1 Masanori Ohno (ISAS/JAXA)

2 HXD: 10-600 keV WAM: 50keV-5MeV XIS: 0.2-12keV X-ray Afterglow (XIS + HXD withToO) Wide energy band (0.2-600 keV) Ultra-low level background Suzaku is the best tool to investigate 1)Emission line 2)Spectral variability in early phase of A.G. Prompt gamma-ray emission (WAM) Powerful tool to investigate the GRB prompt emission spectrum +

3 cross section top view Yamaoka et al. 09 Suzaku HXD-WAM Suzaku/HXD is surrounded by thick (4cm), large (40cm) 20 high-z BGO crystals for active shielding. Wide-band All-sky Monitor (WAM) Energy band: 50—5000 keV Effective area: 400cm 2 @1MeV highest effective area above 300 keV than any GRB missions.

4  Thanks to the WAM large effective area, high quality light curves and spectra can be obtained. 50-110 keV 110-240 keV 240-520 keV 520-5000 keV 1/64 sec, 4 energy bands (BST data) MeV emission GRB 060317 Yamaoka et al. 2009

5 Prompt emission with Suzaku

6 (1)Spectral parameter distribution - true distribution of E peak - differences between long and short GRBs (2) Time variability of GRB spectrum - PL relation in the Flux vs E peak ? a key for the emission mechanism e.g., Ryde & Petrosian (2002), Yonetoku(yonetoku et al. 2003), Liang (Liang et al. 2004) relation (3) MeV emission ? - extra component ? (IC or hadronic?) Kaneko et al. 2006 E peak ~300 keV IC ? proton component ? Energy (keV) 10 2 10 3 10 4 10 5 GRB941017 (Gonzaretz et al. 2003) BATSE E peak distribution νF ν Prompt emission mechanism of GRBs is still mysterious.... Wide energy coverage and large effective area of the WAM could answer for these questions. Prompt emission with Suzaku

7 confirmed GRB 510 (312) possible GRB 320 (151) SGR 374 (12) Solar flare 172 (28) confirmed possible BATSE 4B WAM event list from Aug. 2005 to Feb. 2009 140 GRBs/year ! Bimodal distribution like BATSE Prompt emission with Suzaku T90 Duration distribution by the WAM 93 GCN circulars -63 WAM spectral analysis -22 IPN localization (): triggered event

8 Low energy index αE peak WAM BATSE (Kaneko et al. 2006) -1 0 100 1000 (keV) Prompt emission with Suzaku Large BAT/WAM sample realizes wider energy coverage (15-5000 keV) Unbiased spectral parameter distribution compared with BATSE result Similar α distribution between BATSE and BAT/WAM sample E peak dist. shows broad wings both low/higher energy band (Krimm et al. in prep)

9 Prompt emission with Suzaku Most part of time-resolved E peak follows E peak ∝ L iso 0.5 Rising phase of each pulse tend to be outlier with higher E peak  indicates different Γ and/or emission site during pulse phase e.g., E peak ~ ε B ε e r -1 L 0.5 (synchrotron;Zhang&Meszaros 2002) ~ Γ 0.5 r -0.5 L 0.25 (photosphere; Ioka et al. 2007) Time-resolved spectra as a new probe for the Fireball dynamics GRB061007 ( Ohno et al. 2009) GRB080328 (Nakagawa et al. in prep) L iso (10 52 erg s -1 ) E p,s (keV) L iso (10 52 erg s -1 ) E p,s (MeV)

10 10 100 1000 (keV) WAM Long (T90>2sec) WAM Short(T90<2sec) E peak distribution Ep-Eiso relation + Amati 2006 E iso (10 52 erg) E peak (keV) E peak Short GRBs with z by Swift and WAM Prompt emission with Suzaku Compare the spectral properties between short and long GRBs Spectral correlations like Ep-Eiso relation using BAT/WAM sample Short GRB is harder than Long GRBs Short GRBs do not satisfy Amati relation unlike long GRBs (Ohno et al. in prep)

11 BAT Konus-Wind WAM Swift-BAT Prompt emission with Suzaku WAM detected very high-z (z=6.3) GRB 050904 and the WAM gives a tighter constraint on the spectral parameters (Sugita et al. 2009) GRB050904 also satisfies the Amati relation Dusty environment (n=670cm -2 ) is required to satisfy the Ghirlanda relation. GRB050904 spectrum GRB050904 Ghirlanda relation n=3cm -2 n=670cm -2 +:Ghirlanda et al. 04

12 X-ray afterglow with Suzaku

13 (1) Spectral change in early break of X-ray afterglow (2) Emission lines in the X-ray afterglow Nousek et al. very steepshallowclassical We try to provide the existence of continuous energy injection with broad band spectroscopy (XIS+HXD). Energy injection ? transition from hard to soft … ? Using the Suzaku-XIS to detect the emission lines, we try to CLOSE this chaotic issue.  Prominent iron emission line/edge is independently reported.  XMM-Newton shows emission lines of light element, and no iron line.  Almost all X-ray afterglows show NO emission lines… X-ray afterglow with Suzaku

14 Softening and/or less NH Tashiro et al. 2007 Suzaku/XIS Swift/BAT Swift/XRT Photon index N H 1 10 100 1000 10000 (Time from BAT trigger) Suzaku ToO observation 5.35 hrs after the Swift/BAT trigger No significant emission in hard X-ray band No emission lines in XRT/XIS spectrum (tighter upper limit) Swift/Suzaku light curve indicates very early jet-like break (~1hr)

15 X-ray afterglow with Suzaku Suzaku ToO obs. 9.4hrs after the BAT trigger (up to 1-day obs.) Rapid spectral softening (Γ=1.2  5.3) indicating the exponential cutoff in the prompt spectrum Γ=2.1 afterglow spectrum from Swift/Suzaku continuously. successfully distinguish the prompt spectrum from afterglow one !! 100 1000 10 4 10 5 Swift Suzaku Exp cut + AG comp Yonetoku et al. 2007

16 We performed 3 ToO observations with Suzaku. GRB060105 GRB060904A GRB070328 (3.3 hrs) (9.4 hrs) (5.3 hrs) We have not detected the hard X-ray emission 3 hrs We have to start the follow-up observation within 3 hours at least to detect the hard X-ray emission with the HXD. X-ray afterglow with Suzaku

17 Suzaku can observe both prompt emission and X-ray afterglow of GRBs Prompt emission = Wide-band All-sky Monitor (WAM) GRB detection rate of 140 per year Board winds in the higher (and lower) energy band in E peak distribution Time-resolved E p -L iso is also follow E p – L iso 0.5 but some outliers, reflecting a fireball dynamics. The spectral properties of short and long GRBs are different, indicating a different origin X-ray afterglow = Suzaku XIS and HXD 3 ToO observations have been performed No hard X-ray emission and No emission lines but tighter upper limit Need quick observations within 3hrs The Suzaku conference at Otaru Hokkaido, Japan 29 June - 2 July 2009

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