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Off axis counterparts of SGRBs tagged by gravitational waves. Kazumi Kashiyama (Penn State) w ith K.Ioka , T.Nakamura and P. Meszaros. Why?. The era of gravitational wave astronomy will come soon!. 2 nd generation network . since 2015〜2017.
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Off axis counterparts of SGRBs tagged by gravitational waves Kazumi Kashiyama (Penn State) with K.Ioka, T.Nakamuraand P. Meszaros
Why? • The era of gravitational wave astronomy will come soon! 2ndgeneration network since 2015〜2017 • The “promising target” : compact binary mergers Distance detectable : 〜200Mpc, Event rate : 〜40yr-1 for NS-NS merger • Multi-messenger approach • • GW detectors have bad eyesight! Angular resolution of 2nd generation 〜 10deg2 • SGRBs are the most reliable counterpart, but low-frequent. if θj 〜 0.1, the GW-SGRB simultaneous detection rate〜 0.1yr-1 Off-axis X-ray, optical, radio counterpart searches
Point : “Pre-jet” envelope formation e.g. Lee et al. (2010) , Dessart et al. (2009), Shibata et al. (2011) Mildly relativistic! Optically thick! Neutron-rich! Hyper-massive neutron star Rotational plane of binary Tidal mass ejection Pre-jet envelope (Magnetically or Neutrino driven wind )
Possible off axis emissions from pre-jet envelope Optical (kilonova) Radio active heating in the envelope (β-decay, fission, 56Ni→56Co→56Fe) Li & Paczynski (1998) Metzger et al. (2010) 〜days Radio (afterglow) Interaction between the envelope and interstellar medium Nakar & Piran (2011) 〜years Interaction between the envelope and relativistic jets UV-X-ray ≤ minutes???
Jet penetration problem in SGRBs VS relativistic jet cocoon Black hole (magnetar) + accretion disk
Jet penetration problem in SGRBs Succeed penetration → jet+cocoon ( Fail → jet induced supernovae like? ) No cocoon Relativistic penetration Non-relativistic penetration Failed Penetration
Two possible off axis emissions from jet-envelope interaction 1. Hard X-rays from cocoon breakout 2.Soft X-ray quasi-thermal emission from cocoon itself relativistic jet cocoon Black hole (magnetar) + accretion disk
X-rays from cocoon breakout Jet-cocoon dynamics → Energy budget of breakout photons: Timescale of the emission: @ Too dim to be detected because of the small rcbo cocoon jet
UV-Soft X-rays from cocoon itself Jet-cocoon dynamics → Adiabatic expansion: cocoon @ for ~ minute @ soft X-ray or UV (down scattered) Marginally detectable by future facilities?
Summary • Off axis X-ray counterpart of compact binary mergers could be a key for GW astronomy. • Consider jet and pre-jet envelope interaction • Cocoon breakout emission → too dim • Emission from cocoon itself • could be soft X-ray transient ~minute • might be detected by future facilities? • need to be modeled more precisely. • Failed penetration cases could be also interesting.