Masanori Ohno (ISAS/JAXA)

HXD: keV WAM: 50keV-5MeV XIS: keV X-ray Afterglow (XIS + HXD withToO) Wide energy band ( 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 +

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 highest effective area above 300 keV than any GRB missions.

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

Prompt emission with Suzaku

(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 E peak ~300 keV IC ? proton component ? Energy (keV) GRB (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

confirmed GRB 510 (312) possible GRB 320 (151) SGR 374 (12) Solar flare 172 (28) confirmed possible BATSE 4B WAM event list from Aug to Feb 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

Low energy index αE peak WAM BATSE (Kaneko et al. 2006) (keV) Prompt emission with Suzaku Large BAT/WAM sample realizes wider energy coverage ( 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)

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 GRB ( Ohno et al. 2009) GRB (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)

(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)

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

X-ray afterglow with Suzaku

(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

Softening and/or less NH Tashiro et al Suzaku/XIS Swift/BAT Swift/XRT Photon index N H (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)

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 !! Swift Suzaku Exp cut + AG comp Yonetoku et al. 2007

We performed 3 ToO observations with Suzaku. GRB GRB060904A GRB (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

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