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Long Duration High Energy Transients

Long Duration High Energy Transients. S. R. Kulkarni. An interlude – compactness problem. From sari’s talk (circa 2000). Energy. We measure F~10 -6 erg/cm 2 Cosmological: D ~ 10 28 cm E = 4  D 2 F ~ 10 51 erg. Temporal Variability. dT<1s, T~100  N=T/dT>100.

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Long Duration High Energy Transients

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  1. Long Duration High Energy Transients S. R. Kulkarni

  2. An interlude – compactness problem

  3. From sari’s talk (circa 2000)

  4. Energy • We measure F~10-6 erg/cm2 • Cosmological: D ~ 1028cm • E = 4D2F ~ 1051erg

  5. Temporal Variability • dT<1s, T~100  N=T/dT>100

  6. Implications of short timescale dt=R/c R/c

  7. COMPACTNESS PROBLEM g + g  e+ + e- • dT ~ 1ms  R < 3•107 cm • E ~ 1051ergs  1057 photonshigh photon density(many above 500 keV). • Optical depth T n R~1015>>1 • Inconsistent with the non thermal spectrum! Spectrum: Optically thin Size & Energy: Optically thick ? Paradox ?

  8. C R A ~1/ D B R  R Relativistic Time-Scales • tB-tA~ R (1-) / c ~ R/22c • tC-tA~ R(1-cos )/c ~ R/22c • tD-tA~ /c

  9. The Solution:Relativistic Motion • Due to Relativistic Motion • R = g2 c dT • Eph (emitted) = Eph (obs) / g • tgg = g-(4+2a) nsTR ~ 1015/g4+2a (Goodman; Paczynski; Krolik & Pier; Fenimore; Woods & Loeb; Piran & Shemi; Lithwick & RS 01) g > 100

  10. Relativistic Motion (Lithwick & RS 2001)

  11. References • F. J. Virigili et al. 2013 (ApJ 778) • A. J. Levan et al. 2013 (astroph)

  12. GRB091024A z=1.09

  13. Nuclear sources?

  14. Need a long lived engine • Collapsar model: What determines the duration of the engine? • Tidal Disruption Event • Long duration nicely explained • Magnetar powered?

  15. Tidal Disruption Flare?

  16. Movie!

  17. Grand Overview

  18. Observational difficulties • Most GRB missions work on “triggers” – spikes of emission • Such events are best seen in “imaging triggers” • But satellite must be pointed to the same piece of sky for 1000 s (not the case with Swift) • I wonder how well has the BAT data been analyzed for such objects (or for that matter WFC data)

  19. Tests • Does the object coincide with the nucleus? • Is there a 1998bw-like supernova associated with the object? • What is the total energy loss? (relative to say 1052 erg)

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