Supernovae of type Ia: the final fate of low mass stars

in close bynary systems

Oscar Straniero INAF – Oss. Astr. di Collurania (TE)

CMB Temperature fluctuations

(COBE BOOMERANG

WMAP)

Supernova Cosmology Project

High-z Team (Brian Schmidt & co)

The Universe is Accelerating:

0.25 mag fainter than for an EMPTY Universe

(Saul Perlmutter & co.)

Fainter = Further

Moq2

1

Standard Model

=CDM model

CMB+

SNe+

H0

SNe + CMBSNe + CMB

SNe: Perlmutter et al. 1998, SNe: Perlmutter et al. 1998, Riess et al. 1998Riess et al. 1998

14.51 Gyr (Ho=63)

SNe+WMAP+HST

13.20.4 Gyr (Ho=71)

Spergel et al. 2003

13.70.2 Gyr

GyrMpcsKm

tH oo 9.1671 11

Gyr7.12

Gyr6.10

Gyr4.8

Gyr7.6

SNe Classification

Core collapse of massive stars

Thermonuclear explosion

I b (strong He)

I c (weak He)

SNe

II p

Type II

II L

No H

H

Type I

I a (strong Si)

based on spectra and light curve morphology

Standard Candles Bright Homogeneous No evolutionary effects

Supernovae Ia

Light Curve

L

time

56Ni 56Co 56 Fe

Thermonuclear Explosionof a CO WDM~MChandrasekhar

L MNi

~ 1.4 M

Observed Relations Riess et al. , 1997

Brighter Slower Decline

Dimmer Faster Decline

Calibrated locally

Phillips et al. 1996, 1999

<> = 0.17 mag

Maximum Brightness - Decline Relation

Do Supernovae change with z ??

Hamuy et al., 2000 Ivanov et al. 2000

SN Ia rate is smaller in Ellipticals Cappellaro et al. 1997SN Ia LCs Slower (brighter) in Bluer Galaxies Hamuy et al. , 1995, 1996 Branch et al. 1996

Hints...

Back in time>>Progenitors

Younger&

more metal-poor

…… bombs often fail. Similarly, most models for astrophysical bombs (Sne Ia) often fail.

The conceptually simplest model for a thermonuclear supernova is just an analog of a runaway chemical reaction that become explosive : a conventional bomb.

…… Further, astrophysical bombs must occur naturally and at the correct rate: there must be a convincing astronomical context.

log

log

P

5/3

4/3

M1

M2

Non-degenerate

Non-relativistic

relativistic

collapse

The virial theorem

5.1

3

1

0

2

0

M

Md

M

R

r

Mq

VPR

GMq

r

dMMG

rr

Rrr

g

3

2

3

442 MRMP

457.15.0

83.5 2

Che

eCh

MYif

YM

Massive stars and

core collapse

18.145.0 Che MY

• e-+p n+e (10 MeV)

• 56Fe+ 13+4n (124 MeV)

Limongi, Straniero & Chieffi, 2001

Evolutionary track of low mass stars

0.6 CO

0.55 He 0.2 CO

0.1 He

0.5 He

0.6 CO

WD

MS

RGBHB

AGB

PNM=1 M

=10 Gyr

Remnant: CO WD 0.6 M

Prada Moroni & Straniero 2002

Stellar evolution

M<0.8 M

0.8<M/M<8

8<M/M<11

11<M/M<100

M>100 M

GyrMyr 0.5<Mf /M<1.1 CO WD

Myr Mf

=1.2-1.3 M ONeMg WD

1-10 Myr Mf =1.2-2.5 M Fe (Ye0.45) collapse NS or BH1Myr O (pair jnstability) (Ye=0.5) may or may not explode

Astrophysical Explosive Devices

Gravitational collapse

Induced Core collapse (nuclear runaway fails)

Pair instability, core collapse & O explosion (core collapse fails)

C-deflagration

C or He detonation

C-delayed detonation

Thermonuclear SNe

RGWD

WD WD

Nucleosynthesisin Thermonuclear

SNe

He-detonation

C-delayed detonation

C-deflagration

SNe Ia Light Curves: mass

and metallicity effects

Domínguez, Hoflich, Straniero 2001

Most of the accreted material is lost during the H-pulse:

too long time

H accreting WDs

RG MS

Merging scenario:Double degenerate systems: CO+CO a) GWR loss

b) secondary tidal disruption

c) accretion 10-5 Myr-1

Too fast accretion

(M=810-6 M yr-1)

Double Degenerate CO WDs

(M=10-8 M yr-1)

Single Degenerate.

Massive WDs: the lifting effect of

rotation

H

HeCO

Dominguez, Straniero, Isern & Tornambe’ 1996

Double DegenerateAngular momentum deposition & GWR

c) accretion 10-5 Myr-1 (expansion)

d) “critical” accretion (contraction)

e) tri-axial configuration and energy loss via GWR

f) balance between ang. mom. deposition and energy loss (steady accretion)

g) Viscous dissipation and explosion

d

c ef g

---- disk ---- WD

Piersanti, Gagliardi, Iben & Tornambe’ 2003

Open Problems:

Progenitors ?? Accretion, Rotation. Propagation of the burning front (1D/3D) ?? Transition density How stellar populations evolve with z ??

Our main results for SNe Ia: Up to MMAX =0.2 mag C/O WDs due to different MMS

correlated with vph & trise

No dependence of MMAX with initial Z

The future