Sec$on 9.
Radia$on from supernovae
9.1 Observa$ons of supernovae
9.2 Radia$on mechanism of supernovae

Goals of this lecture• Standard proper$es of stars• Stellar structure and proper$es• Stellar evolu$on• Origin of the elements in the Universe• Nucleosynthesis in stars and supernovae• Explosion mechanism of supernovae• Topics in $me-domain astronomy• Radia$on from explosive phenomena• Mul$-messenger astronomy

Sec$on 9.
Radia$on from supernovae
9.1 Observa$ons of supernovae
9.2 Radia$on mechanism of supernovaeSpot the diﬀerence!!Answer

Spot the diﬀerence!
(level **)0.25 deg(C) Rod Pommierh.ps://www.sbig.com

AnswerSupernova(C) Rod Pommierh.ps://www.sbig.com

Observa$ons of transients• Light curve• Time evolu=on of luminosity(total or in a certain band)• Spectra• Flux as a func=on of wavelengths(and their =me evolu=on)

Light curves-20Type Ia
Type Ib and Ic
Type II

1043 erg s-1

Type I

1042

1041

Absolute magnitude

-18

-16

- Peak- L(Ia) > L(Ib, Ic)-14

Type II- plateau- L(Ia) > L(II)-12-10050100
150
200
250
Days after the explosion

300350Spectra of supernovae
H
Relative flux + const- Thermal con$nuum

3000

Si- Broad absorp$on- Doppler shi[He

4000

5000
6000
7000
Restwavelength(Å)
Wavelength(A)- Associated withemission component8000

4 types of supernovae
Type I
Si

Yes

HNo

Yes
Type IINo

Core-collapse SNeHeType Ia

Yes

Thermonuclear
SNe
Type Ib

No
Type Ic

Core-collapse SNeLine proﬁle2

H alpha(6563 A)

Flux

Absorp$on“P-Cygni”
Proﬁle106000

6200

6400
6600
Wavelength (A)68007000

Observer

Doppler eﬀects
=3=cv
c0=3v
( 0)
=c0

λλ0

Line proﬁle2H alpha(6563 A)

v/c = 163/6563

Flux

Absorp$on=>
v = 0.025 x c~ 7,000 km/s

1~6400
0
6000

6200

6400
6600
Wavelength (A)

6800

7000

Sec$on 9.
Radia$on from supernovae
9.1 Observa$ons of supernovae
9.2 Radia$on mechanism of supernovae

Light curves-20Type Ia
Type Ib and Ic
Type II1043 erg s-1

Type I1042

1041

Absolute magnitude-18-16- Peak- L(Ia) > L(Ib, Ic)-14

Type II- plateau- L(Ia) > L(II)-12-10050100
150
200250Days after the explosion

300350What determines the luminosity and$mescale of radia$on?

What can we learn from observa$ons?

Hea$ng source of supernovae
1. Radioac$vity (56Ni)
Important in all the types
Type Ia > Core-collapse
2. Shock hea$ng
Important for large-radius star (Type II)
3. Interac$on with CSM
Ekin => Eth (Type IIn)
4. Magnetar?
Erot => energy loss by spin down

56Ni

e capture56Co

e capture
pos decay

τ = 8.8 days

τ = 110 daysNadyozhin 94

Type Ia
SNSun56Ni

SN ejecta
Op$cal/infrared photons
Gamma-rays(E loss by Compton scat=> photoelectric absorp$on)

y toward optical wavelengths. As was noted byes & Wagoner (1995), the line opacity between 2000
000 A! falls o† roughly as d ln i/d ln j D [10. We willj
that the steepness of this decline toward the opticaltimes, where p is the probability per scattering for escape,which is accomplished by Doppler shifting out of resonance. In spite of the possiblyof scatterings-13 large number-3
needed for escape, a photon spends only a small fraction of

Opacity in supernova ejecta (Type Ia SN, ρ = 10-9κ (cm2 g-1)

10-10

103

10-1110210-1210-13

10-14

10-15

e-

10-2

10-16

電子散乱

10-3

10-17

10-18

opacity [cm ]10-1g cm )束縛遷移

10lines

1.0
10-1

free-freebound-free
10

3

10

4

wavelength [A]1.ÈMonochromatic opacity sources at maximum light for a Chandrasekhar-mass model of a Type Ia supernova from a time-dependent, multiPinto& Eastman
2000
cy, LTE calculation. The physical conditions are o \ 10~13 g cm~3, T \ 2.5 ] 104 K and t \ 14 days. The line opacity
shown
here is the frequency
eraged expansion opacity, as given by equation (9) (see text) and not the much larger monochromatic Sobolev opacity. The line opacity has not been
below 2 ] 10~14 cm~1, so as not to obscure the contributions from continuum opacity sources.

Light curves-20Type Ia
Type Ib and Ic
Type II56Ni

1043 erg s-1

Absolute magnitude-18

Shock hea$ng

1042 erg s-1-1656Ni~20 days-14-12-10Type Ia SNe eject
more 56Ni~100 days
050100150200250
Days after the explosion

300350Observa$ons <=> physical quan$$es

Stripped2envelope2SN2(Type2Ib/c,2Ia)
Light curves 56Spectra
E,2Mej,2and2M( Ni)
1/2 Mej-1/2v~EL
M(56Ni)+ chemical composi$on
2 spectrum

Flux

M(56Ni)t2~2κ1/22EG1/42Mej3/4~2202dt

velocity~2E1/22MejG1/2
10
5600

5800

3E, Mej, M(56Ni), X (element)

6000
6200
Wavelength (A)

6400

6600

Summary: Radia$on from supernovae•Erad ~ 1049 erg<< Ekin (1051 erg) << Egrav (1053 erg)

• Power source• Radioac=vity ( Ni)• Shock hea=ng, interac=on with CSM, magnetar, …
• Timescale of emission• Photons diﬀuse out from SN ejecta• bound-bound transi=ons and e-sca.ering
Mej Ek• Typical =mescale t~~κκ Mejv
56

1/2

3/4

1/2

1/2

-1/4

-1/2