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Swift ‘sub-prime’ GRB search

Swift ‘sub-prime’ GRB search. Concept and motivation Implementation Goal is to bring proposal to LSC-V in March. LSC (so far): E. Harstad**, R. Frey, I. Leonor (U of Oregon) Swift BAT: J.R. Cummings, H.A. Krimm (NASA GSFC), D.M. Palmer (LANL). Swift BAT. FOV: 1.4 sr

stephen-david
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Swift ‘sub-prime’ GRB search

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  1. Swift ‘sub-prime’ GRB search • Concept and motivation • Implementation • Goal is to bring proposal to LSC-V in March LSC (so far): E. Harstad**, R. Frey, I. Leonor (U of Oregon) Swift BAT: J.R. Cummings, H.A. Krimm (NASA GSFC), D.M. Palmer (LANL) R Frey U Maryland LSC-V 18 Dec 2008 G080655-00-Z

  2. Swift BAT • FOV: 1.4 sr • In general, a significant rate increase plus an image (position) • “a burst”, GCN notice, slew • Two classes of “sub” GRBs: • Real sources just outside the FOV (“rate trigger”) • Real sources with rate below the usual threshold (“sub threshold”) We are interested in both. R Frey U Maryland LSC-V 18 Dec 2008 G080655-00-Z

  3. BAT trigger rate and threshold Swift internal only • Swift’s goal is primarily to report GRBs with very high purity • There are clearly good GRBs below the usual BAT threshold Burst significance Trigger rate (au) R Frey U Maryland LSC-V 18 Dec 2008 G080655-00-Z

  4. GRB and GW brightness GRBs which are dim in gamma-rays are not necessarily correlated with low GW brightness • e.g. short GRBs are dimmer than long (even though nearer); but are much stronger in GW luminosity • gamma-rays from GRBs are beamed: position of Swift in beam is significant effect R Frey U Maryland LSC-V 18 Dec 2008 G080655-00-Z

  5. Analysis outline • The rate triggers (outside FOV): many of these already show up in the GCN circulars as GRBs after being confirmed by IPN, et al • High purity; not a large number of triggers • No position – analyze using time-coincidence analysis • The sub-threshold triggers: • Stay close to nominal Swift GRB threshold • The trigger information must be disentangled from several BAT log files and data products (in progress: Emelie) • Analyze as for main S5 GRB pipeline • This is a “standard” ExtTrig style search • Use reviewed pipelines • Omega pipeline is good candidate for bursts pipeline. CBC ? • Current plan involves only S5 R Frey U Maryland LSC-V 18 Dec 2008 G080655-00-Z

  6. Next steps • The Swift data is already public, including logs files, debug streams, etc. No permissions needed. • Some special knowledge is required to interpret it. But the BAT folks have been very helpful. • The BAT crew simply informs the Swift PI that this activity is taking place and that they are to be co-authors on any resulting publications. • Only impact on LSC resources is the analysis review. • We would like to propose this to the LSC-V for the Spring LVC meeting R Frey U Maryland LSC-V 18 Dec 2008 G080655-00-Z

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