Swift 2010. 4. 19. 2010 Kyoto GRB Conference BAT2 GRB Catalog Prompt Emission Properties of Swift...
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Transcript of Swift 2010. 4. 19. 2010 Kyoto GRB Conference BAT2 GRB Catalog Prompt Emission Properties of Swift...
2010. 4. 19. 2010 Kyoto GRB Conference Swift
BAT2 GRB CatalogBAT2 GRB CatalogPrompt Emission Properties of Prompt Emission Properties of
Swift GRBsSwift GRBs
T. Sakamoto (CRESST/UMBC/GSFC)
on behalf of Swift/BAT team
2010. 4. 19. 2010 Kyoto GRB Conference Swift
ContentsContents
BAT2 GRB catalog Overview of the BAT2 GRB catalog Short GRBs vs. Long GRBs Observed properties vs. redshift Summary
2010. 4. 19. 2010 Kyoto GRB Conference Swift
BAT2 GRB CatalogBAT2 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: T902 s S-GRB: T90 < 2 s
• 146 known-z GRBs
2010. 4. 19. 2010 Kyoto GRB Conference Swift
Overview of BAT2 GRB CatalogOverview 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 Epeak (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
2010. 4. 19. 2010 Kyoto GRB Conference Swift
Short GRBs vs. Long GRBsShort GRBs vs. Long GRBs
2010. 4. 19. 2010 Kyoto GRB Conference Swift
(15-150 keV)
(25 - 5000 keV)
70 s
32 s
0.5 s
TT9090 Duration Duration
S-GRBs: 9%
S-GRBs: 25%
2010. 4. 19. 2010 Kyoto GRB Conference Swift
(Total 402)
(Total 38)
(Averaged -1.6)
(Averaged -1.2)
BAT Time-ave PL Photon indexBAT Time-ave PL Photon index
2010. 4. 19. 2010 Kyoto GRB Conference Swift
Discussion: Short on S-GRBs in BATDiscussion: 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.
2010. 4. 19. 2010 Kyoto GRB Conference Swift
Discussion: Short on S-GRBs in BATDiscussion: 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.
2010. 4. 19. 2010 Kyoto GRB Conference Swift
Prompt Emission Properties Prompt Emission Properties vs. vs.
RedshiftRedshift
2010. 4. 19. 2010 Kyoto GRB Conference Swift
TT9090 vs. Redshift vs. Redshift
2010. 4. 19. 2010 Kyoto GRB Conference Swift
TT9090 vs. Redshift vs. Redshift
z=2 z=3z=4 z=5 z=6 z=7 z=8
2010. 4. 19. 2010 Kyoto GRB Conference Swift
TT9090 vs. Redshift vs. Redshift
2010. 4. 19. 2010 Kyoto GRB Conference Swift
BAT PL PhIndex vs. RedshiftBAT PL PhIndex vs. Redshift
2010. 4. 19. 2010 Kyoto GRB Conference Swift
BAT PL PhIndex vs. RedshiftBAT PL PhIndex vs. RedshiftEpeak- relation(Sakamoto et al. 2009)
2010. 4. 19. 2010 Kyoto GRB Conference Swift
Discussion: BAT High-z GRBsDiscussion: BAT High-z GRBs
• T90 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.
2010. 4. 19. 2010 Kyoto GRB Conference Swift
SummarySummaryL-GRBs vs. S-GRBs
• BAT <T90> = 70 s (BATSE <T90> = 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)
• T90 is not all long• Observed spectrum is not soft
Stay tune for the BAT2 GRB catalog!Stay tune for the BAT2 GRB catalog!