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Swift 2010. 4. 19. 2010 Kyoto GRB Conference BAT2 GRB Catalog Prompt Emission Properties of Swift GRBs T. Sakamoto (CRESST/UMBC/GSFC) on behalf of Swift/BAT team
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Swift 2010. 4. 19. 2010 Kyoto GRB ConferenceContents BAT2 GRB catalog Overview of the BAT2 GRB catalog Short GRBs vs. Long GRBs Observed properties vs. redshift Summary
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference BAT2 GRB Catalog 476 GRBs (from GRB 041219 to GRB 091221) - including 25 GRBs found in ground processing 476 GRBs 426 Long-duration GRBs (L-GRBs) 41 Short-duration GRBs (S-GRBs) 9 Short-duration GRBs with extended emissions (S-GRBs w/ E.E.) (89%) (9%) (2%) 3323 time-resolved spectra Working definition of L-GRB vs. S-GRB: L-GRB: T 90 2 s S-GRB: T 90 < 2 s 146 known-z GRBs
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference Overview of BAT2 GRB Catalog Updates on BAT In-orbit Calibration GRB Sky map Duration – Duration distribution – Duration vs. Hardness (BAT/BATSE/HETE-2) Peak flux and fluence – Peak flux vs. fluence – fluence vs. fluence (BAT/BATSE/HETE-2 ) BAT time-averaged spectral properties –BAT PL Photon index distribution (short vs. long) –BAT E peak (CPL fit) distribution BAT time-resolved spectral properties –PL Photon index distribution (time-ave vs. time-res) –Line of death problem Observed prompt emission properties vs. redshift
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference Short GRBs vs. Long GRBs
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference (15-150 keV) (25 - 5000 keV) 70 s 32 s 0.5 s T 90 Duration S-GRBs: 9% S-GRBs: 25%
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference (Total 402) (Total 38) (Averaged -1.6) (Averaged -1.2) BAT Time-ave PL Photon index
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference Discussion: Short on S-GRBs in BAT BAT: 10% S-GRBs (90% L-GRBs) BATSE: 25% S-GRBs (75% L-GRBs) Factor of 2.5 small # on S-GRBs in BAT Histograms of 50-100 keV fluence of S-GRBs BAT BATSE No significant difference in the S-GRBs fluence distribution … 1. BAT is not missing S-GRBs 2. BAT is missing S-GRBs Possibility BATSE’s missIDs: TGFs, SGRs, … Might be a room to improve S-GRB detection in BAT BATSE - Rate trigger BAT - Rate trigger - Imaging vs.
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference Discussion: Short on S-GRBs in BAT BAT: 10% S-GRBs (90% L-GRBs) BATSE: 25% S-GRBs (75% L-GRBs) Factor of 2.5 small # on S-GRBs in BAT Histograms of 50-100 keV fluence of S-GRBs BAT BATSE No significant difference in the S-GRBs fluence distribution … 1. BAT is not missing S-GRBs 2. BAT is missing S-GRBs Possibility BATSE’s missIDs: TGFs, SGRs, … Might be a room to improve S-GRB detection in BAT BATSE - Rate trigger BAT - Rate trigger - Imaging vs.
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference Prompt Emission Properties vs. Redshift
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference T 90 vs. Redshift
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference T 90 vs. Redshift z=2 z=3 z=4 z=5 z=6 z=7 z=8
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference T 90 vs. Redshift
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference BAT PL PhIndex vs. Redshift
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference BAT PL PhIndex vs. Redshift E peak - relation (Sakamoto et al. 2009)
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference Discussion: BAT High-z GRBs T 90 is not all long. Observed spectrum is not soft. BAT High-z GRBs: If you are interested in hunting high-z GRBs… Detector with a softer energy band (e.g. X-ray) might not help. Detector with a large effective area (high sensitivity). Large FOV (high-z GRB is rare). Sophisticated on-board trigger/localization software.
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Swift 2010. 4. 19. 2010 Kyoto GRB Conference Summary L-GRBs vs. S-GRBs BAT = 70 s (BATSE = 30 s) Significantly longer duration in BAT (softer energy band) BAT S-GRBs are harder than L-GRBs (large overlap) Lack of S-GRBs in BAT: BAT S-GRBs 10% (BATSE S-GRBs 25% ) Observed properties vs. Redshift (BAT high-z GRBs) T 90 is not all long Observed spectrum is not soft Stay tune for the BAT2 GRB catalog!
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