Swift Kyoto GRB Conference BAT2 GRB Catalog Prompt Emission Properties of Swift GRBs T. Sakamoto (CRESST/UMBC/GSFC) on behalf of Swift/BAT team
Swift Kyoto GRB ConferenceContents BAT2 GRB catalog Overview of the BAT2 GRB catalog Short GRBs vs. Long GRBs Observed properties vs. redshift Summary
Swift Kyoto GRB Conference BAT2 GRB Catalog 476 GRBs (from GRB to GRB ) - 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
Swift 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
Swift Kyoto GRB Conference Short GRBs vs. Long GRBs
Swift Kyoto GRB Conference ( keV) ( keV) 70 s 32 s 0.5 s T 90 Duration S-GRBs: 9% S-GRBs: 25%
Swift Kyoto GRB Conference (Total 402) (Total 38) (Averaged -1.6) (Averaged -1.2) BAT Time-ave PL Photon index
Swift 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 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.
Swift 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 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.
Swift Kyoto GRB Conference Prompt Emission Properties vs. Redshift
Swift Kyoto GRB Conference T 90 vs. Redshift
Swift Kyoto GRB Conference T 90 vs. Redshift z=2 z=3 z=4 z=5 z=6 z=7 z=8
Swift Kyoto GRB Conference T 90 vs. Redshift
Swift Kyoto GRB Conference BAT PL PhIndex vs. Redshift
Swift Kyoto GRB Conference BAT PL PhIndex vs. Redshift E peak - relation (Sakamoto et al. 2009)
Swift 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.
Swift 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!