Faint Core-Collapse Supernovae with Fallback Takashi Moriya (IPMU, University of Tokyo) N. Tominaga (Konan Univ.), M. Tanaka (IPMU), K. Nomoto (IPMU), D. Sauer (Stockholm Univ.), P . Mazzali (MPA), & Maeda (IPMU)
long GRBs - death of massive stars • collapsar? • SN-GRB connection • magnetar? GRB 100316D/ SN 2010bh 5 Day 1.39 4 Flux (f � ) + constant 2.33 3.3 3 4.3 5.2 2 6.1 7.0 1 11.0 21.2 Ages in rest frame time after BAT trigger 4000 5000 6000 7000 8000 9000 10000 Rest Wavelength (Å) Chornock et al. (2010)
long GRBs without a supernova • GRB 060614 (Della Valle et al. 2006)
why? • some long GRBs not associated with death of massive stars? • an alternative mechanism for long GRBs not related to death of stars? • associated SNe are too faint to be observed? • the SNe must be as faint as - 16 mag at maximum (case of GRB060614) • such faint type Ic SNe have not been discovered
discovery of the missing piece: SN 2008ha • very faint (Valenti et al. 2009; Foley et al. 2009) Over luminous • ~ -14 mag at maximum Type Ia ( SN 1991T ) • a peculiar type Ia SN? • too small expected ejecta mass (~ 0.1 Msun) SN 2002cx normal Type Ia ( SN 2003du ) • a core-collapse SN? SN 2008ha • a very faint type Ic SN?
how a type Ic SN becomes faint? 1. 2. 3. C + O Injection of energy Propagation of shock 4. 5. Fallback Inner layer does not exceed Ejection of the outer layer escape velocity
SN 2008ha: a faint core-collapse SN with fallback • numerical calculations • hydrodynamics, nucleosynthesis, & radiation transport • It Works! • a core-collapse model of SN 2008ha M MS = 13 M ⊙ = > M preSN = 2 . 7 M ⊙ E kin = 1 . 2 × 10 48 erg , M ej = 0 . 074 M ⊙ , M Ni56 = 0 . 003 M ⊙ -14 8000 Bolometric LC Photospheric velocity (13COG) 13COG Photospheric velocity (25CO: LC fitted) 13CO(269) Na I D 7000 13CO(276) -13.5 O I 7774 absolute bolometric magnitude 6000 -13 velocity (km s -1 ) 5000 -12.5 4000 3000 -12 2000 -11.5 1000 -11 0 0 10 20 30 40 50 60 70 0 10 20 30 40 50 days days since the explosion
conclusion long GRBs without observed SNe: the associated SNe were just too faint! long GRBs without observed SNe are also related to death of massive stars
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