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GRB sensitivity and Search for Delay Emission

GRB sensitivity and Search for Delay Emission. Magda and David N. 3sigma, un-triggered bursts, Zang=18-27, binsize= 1.2 or 1.6 Red Solid / Red dashed = 2. Better sensitivity for triggered bursts because we know Zang Black/Blue = 1.76 lower than Julie’s.

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GRB sensitivity and Search for Delay Emission

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  1. GRB sensitivity and Search for Delay Emission Magda and David N.

  2. 3sigma, un-triggered bursts, Zang=18-27, • binsize= 1.2 or 1.6 • Red Solid / Red dashed = 2

  3. Better sensitivity for triggered bursts • because we know Zang • Black/Blue = 1.76 lower than Julie’s

  4. binsize = 1.5, Blue/Black = 1.62 • binsize = 2.0, Blue/Black = 1.76 • best binsize in each case, Blue/Black = 1.59 • Trigger 4 is not making sensitivity a lot better

  5. Sensitivity improves with energy cutoff, But, trigger 4 makes less difference

  6. -18 -14s 14 - 47s 47 - 80s 80 - 113s 113 - 211s • GRB940217, T90=150s • THE= 90min, Emax= 18GeV • GRB970417, T90=8s • THE= 8s, Emax= TeV • GRB941017, T90=77s • THE= 200s, Emax= 200MeV

  7. Plan: • Propose search(es) for delayed emission (done) • Understand the effect of trials factors for the search(es) – probability of detecting a fake burst. (in progress) • Efficiency of search(es) to detect a real • burst. (next)

  8. Proposed Searches: CASE 1.- For delayed emission happening at T90 and/or lasting longer. CASE 2.- For delayed emission lasting tens of seconds or shorter, starting after T90. CASE 3.- For delayed emission lasting hundreds of seconds, starting after T90.

  9. CASE 1 • Tbin_min = T90/2. • Tbin_increase = P% of T90, let say 10% • T_tot = M*T90 or • find Nsigma or fixed time (1000s) • IDEA: • Start with a time bin of Tbin_min. • Increase the time bin by Tbin_increase letting lower edge fixed. • - Ends at T_tot

  10. CASE 3 (CASE 2) • Tbin = 100s (10s) • Tbin_change = 50s, 10s, 1s (5s, 1s, 0.1s) • T_tot = 4hr or until GRB is out of field of view. • (maybe 500s) • IDEA: • Divide T_tot in k Tbin intervals • Look for the Tbins above Nsignificance • Move tbins by 50s and compare with the • above. • If no improvement and no tbins above significance, quit • Otherwise, take better binning. • Increase tbin by 10s, one edge at the time, keep bigger tbin if improves significance. • If the tbin size does not change, decrease tbin by 10s • Divide tbin(s) in 10s intervals and repeat.

  11. Issues to study: • Significance required in detection. • T_tot, number of tbins and effect in trials, • minimum fluence to detect. • Efficiency to detect a burst of D duration. • spectral index, E cutoff • STATUS: • We finished the sensitivity study • We are working on the MC, almost done with • Case 1.

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