Multicolor light curves ofelectron-capture supernovae
Nozomu Tominaga(Konan Univ.)
NT, Blinnikov, Nomoto 2013 ApJ 771 L12

31st Oct 2013
SN conference, Kyoto

Outline Introduction
 Super Asymptotic Giant Branch star Electron-Capture Supernovae Theoretical light curves of ECSNe
 Observable features
 Pulsar contribution

 Comparisons with possible ECSNe
 SN1054 (Crab SNR) SN2008S

Introduction

Please refer Mr. Jones’ talk, Mr.Takahashi’s poster.

Super AGB star w/ ONeMg core
Typical mass range: ~8-10M8

Siess 07
Poelarends+08
Jones+13
Takahashi+13Enclosed mass

He-rich envelope
X(He)~0.8-0.7
Siess 07

Strongly degenerated
O+Ne+Mg core
Nomoto 84

Time until the explosion

Please refer Tuesday morning session.

Electron capture supernovae
Successful explosion in 1D!!

Kitaura + 06
Burrows+07
Janka + 08
Wanajo + 09,13a,b

Explosion properties
Low explosion energy
E~1.5x1050erg
Neutron starMB~1.36M8
Small ejected 56Ni mass
Motivation
M(56Ni)~0.002-0.004M8
Let’s calculate a theoretical lightcurveECSNHigh
Ni/Feofratio
Ni/Fe~1.3-1.5
based on first-principle simulations.

Theoretical light curves

Progenitor models
Density structure

HR diagram
They locate at a
tip of SAGB stars.

Hydrostatic envelope
Menv=2.0-4.7M8
Xenv(H)=0.2-0.7

Light curves
Bolometric LCs(adopted STELLA, Blinnikov+98,00,06)

V-band LCs

Typical brightnessof SNe IIP(Richardson+02)

ECSNe with larger Menv
or higher X(H) have alonger and fainter plateau.

Observational features-how to distinguish ECSNe from Fe-CCSNe Plateau
 slightly short duration: 60-100 days (~100day)
 slightly slower photospheric velocity:

3-4x103 km s-1 (~3-6x103 km s-1)
(faint Fe-CCSNe: ~1-2x103 km s-1)
 similar brightness: L~1042 erg s-1
 Tail fainter: Mbol~ -11mag at the beginning (~13mag)

Luminosity drops by ~4mag.

Pulsar contribution
 ECSN is a NS-forming SN.
 Crab pulsar (Hester 2008)
 Lsd ∼ 5 x 1038 erg s−1
 tsd ~ 700 yr
 nsd ~ 2.5

 Initial spindown luminosity
 Lsd,0 ∼ 3.3 x 1039 erg s−1

The spin-down luminosity could
contribute to the LC of ECSN.
Note: however, we do not know how
efficiently the energy is deposited to theenvelope just after the explosion.

©ChandraPulsar contribution~7mag differenceComparisons with observations

Possible ECSNe
 SN1054 ( Crab SNR) (Davidson + 82; Nomoto + 82) small ejecta mass: 4.6±1.8M8 (Fesen + 97)
 low kinetic energy: E~3x1049erg for Mej=1-2M8
 high He abundance: 1.6<He/H<8 (Davidson 73)
 high Ni/Fe ratio: Ni/Fe~0.76-4 (Henry 84) SN2008S (Prieto+08; Botticella+09)
 dust-surrounding progenitor
 faint light curve slow evolution

Observations of SN1054(Pskovskii 1985; Stephenson&Green 2002)

They are enscrolled in historiographies.
 We take 3 points with large error bars.
1.

July 4, 1054 (possibly fromMay 10, 1054)
as bright as Venus
mopt ∼ −3.5 to −5
2. until July 27, 1054
visible in the daytime
mopt ∼ −3
3. April 6, 1056
disappeared in the night
mopt ∼ 6

Meigetsuki (明月記)
Teika Fujiwara (藤原定家)

Comparison with SN1054

The last point cannot be reproduced
without pulsar or any energy source otherthan 56Ni, as suggested in Sollerman+01.

Multicolor LCs of SN2008S
A fainter and longer
plateau is needed.
SN2008S

Analytic speculation for SN2008S
 Explosion energy
 E~3.5x1048erg

 Envelope mass
 Menv ~ 3.4M8
Dependence of plateau (Eastman + 94)

 Shock breakout luminosity
 L ~ 1.4x1042erg s-1 (eq. in Matzner & McKee 99)

 dust cavity with Rcavity~1011km(cf. Rcavity~3-10x1011km for SN2008S, Botticella+09)

Summary We present first self-consistent multicolor

light curves of ECSNe.
 ECSNe have
 a plateau with L ∼ 1042 erg s-1 and t ∼ 60–100 days,
 a faint tail (luminosity drops by ∼4 mag), and a photospheric velocity at plateau of 3-4x103 km s-1.

 Crab SNR is a remnant of ECSN SN1054.
 The model with 1.5 x 1050 erg is too energeticfor SN2008S.

Can ECSNe explode with E~1048erg?