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Light curves of electron-capture and �Fe-core-collapse supernovae: �A new diagnostic of electron-capture supernovae

Masato Sato

(The Graduate University for Advanced Studies, SOKENDAI and NAOJ)

Collaborators：Nozomu Tominaga (NAOJ), Sergei I. Blinnikov, Marat Sh. Potashov (NRC Kurchatov Institute), Takashi J. Moriya (NAOJ), Daichi Hiramatsu (CfA | Harvard & Smithsonian)

Jan. 29^th, 2024

Transients Down Under

masato.sato@grad.nao.ac.jp

arXiv:2402.04611

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Core-collapse supernovae (CCSNe)

O+Ne+Mg

C+O

O+Ne+Mg

C+O

M_MS~8-10M_☉

M_MS≳10M_☉

Red supergiant (RSG)

↓

Fe-core-collapse (FeCC) SN

Super-AGB (SAGB) star

↓

Electron-capture (EC) SN

Mass boundary ?

Only 1 promising candidate

1. Introduction

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SN 2018zd

ECSN

(9.6Mpc)

low-mass FeCCSN

(15.6Mpc)

Hiramatsu+21

Callis+21

Distance uncertainty

Reveal the observational differences

Hiramatsu+21

1. Introduction

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Light curves of ECSN & low-mass FeCCSN

w/o CSM
little variation of E_exp

ECSN

low-mass FeCCSN

Blue

U~-16mag

Kozyreva+21

U~-12mag

Time [days]

Absolute magnitude

Core(Nomoto 87)+Envelope(MESA, Jones+13)

Time [days]

Absolute magnitude

M_ZAMS=9M_☉(Sukhbold+16)

ECSN: Blue plateau

1. Introduction

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CSM varieties

SN observations

RSG observations

Förster+18

Goldman+16

10^-6-10^-4　

M_☉/yr

10^-4-10^-2　

M_☉/yr

1. Introduction

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Explosion energies

Observational indications

Martínez+22

~10⁵⁰-10⁵¹erg

Theoretical estimations

Kitaura+06

Time

Explosion energy [10⁵¹erg]

Burrows+21

~10⁵⁰ erg

ECSN

FeCCSN

1. Introduction

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This work

Motivation
Identify ECSNe and reveal their nature.
Investigate robust observational differences between ECSNe and low-mass FeCCSNe.
This work
Calculate multicolor light curves of ECSNe and low-mass FeCCSNe using STELLA (Blinnikov+93) with

various CSM density profiles
various explosion energies

Propoes a new diagnostic method of ECSNe.

1. Introduction

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Progenitor models

	Progenitors
FeCC RSG	ZAMS mass M_ZAMS=9-12M_☉ (sukhbold+16)
EC SAGB	Envelope mass M_env=2.0-4.7M_☉ Envelope H abundance X(H)_env=0.2-0.7 (Tominaga+13)

RSG

SAGB

SAGB has low-density and extended envelope

Radius [cm]

Density [g/cm³]

2. Results

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Explosion energies and CSM density profiles

	Explosion energy E_exp [10⁵¹erg]		CSM radius r_out [cm]
FeCC	0.05-1.4	10^-6-10^-2	10¹⁴-10¹⁵
EC	0.06-1.4	10^-6-10^-2	10¹⁴-10¹⁵

Wide ranges of E_exp and CSM density profiles

2. Results

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w/o strong CSM interaction

Bolometric

u - g

FeCCSN

ECSN

Absolute magnitude

Time [days]

	Progenitor	E_exp
FeCC	M_ZAMS=9M_☉	3.6×10⁵⁰ erg
EC	M_env=3M_☉,X(H)_env=0.7	1.0×10⁵⁰ erg

Degenerate

Blue plateau of ECSN

2. Results

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w/ strong CSM interaction

	Progenitor	E_exp		r_out
FeCC	M_ZAMS=9M_☉	3.6×10⁵⁰erg	10^-2 M_☉/yr	10¹⁵ cm
EC	M_env=3M_☉,X(H)_env=0.7	1.0×10⁵⁰erg	10^-2 M_☉/yr	10¹⁵ cm

Blue plateau after CSM interaction

Bolometric

u - g

Time [day]

Absolute magnitude

FeCCSN

ECSN

2. Results

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Blue plateau of ECSN

Hot region inside the recombination front is observed.

Photosphere

Recombination front

Photosphere

Recombination front

Radius [cm]

Time [days]

FeCCSN

ECSN

3. Discussion

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Diagnostic method of ECSN

t_PT

t_PT/2

Absolute magnitude

Time [day]

t_PT[day]

Bluer

Redder

Identify ECSNe with blue plateau

FeCCSN

ECSN

3. Discussion

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Application to SN 2018zd

SN 2018zd

t_PT[day]

SN 2018zd is diagnosed as an ECSN

FeCCSN

ECSN

3. Discussion

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Find candidates in past

Preliminary

t_PT [days]

Data from Open SN Catalog

3. Discussion

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Summary

ECSNe show blue plateau originated from low-density envelope of SAGB progenitors.
Propose a new diagnostic method of ECSNe.
We will find and investigate ECSN candidates in past, present, and future.

4. Summary