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Type Ia Supernovae
Jordi Isern
Institute for Space-Sciences
(CSIC-IEEC)
Barcelona
2nd ASTROGAM Workshop
Paris, March 26th 2015
Overview on Supernovae
Taxonomy:
Light curves
The light curve is essentially powered by
Supernovae
the desintegration
chain
Ni  56Co  56 Fe
Can   rays be used as a diagnostic tool?
56
Clayton et al 1969
Gehrels et al 1987
Ambwani & Sutherland 1988
Burrows & The, 1991
The et al 1993
Ruiz-Lapuente et al 1993
Hoflich et al 1994
Kumagai & Nomoto 1995
Woosley & Timmes 1997
Gómez-Gomar et al 1998
Summa et al 2013
(from S. Woosley ppt)
IBIS/ISGRI flux in the 67 – 190 keV band
(2.2 ± 0.4) x 10-4 cm-2 s-1 sig ~ 5.4 σ
Rev: 1380-1385
SPI: Emission excess in the 700 -1100 band
Excess in the 650 – 1300 kev band:
(1.2±0.4 (stat)±0.1(sys) x 10-3 cm-2s-1 sig ~3σ
Broad line
Center: 155.0 ±1.9 keV
FWHN: 5.3 ± 3.9 keV
Flux: (2.4 ±1.6) x 10-4 cm-2 s-1 (3.5 σ)
Transient
Churazov et al. 2014
Rev 1390-1396 (~46 – 63 days a.e.)
SN2014J
• These arguments:
• Absence of H at the moment of the explosion
• The explosion should produce at least ~ 0.3 M0 of 56Ni to
account for the light curve and late time spectrum
• The short risetime of the light curve indicates that the
exploding star is a compact object
• Progenitors should be long lived to account for their presence in
all galaxies, including ellipticals
SNIa are caused by the thermonuclear explosion
of a C/O white dwarf near the Chandrasekhar’s mass
in a close binary system
(He white dwarfs detonate and are converted in Fe
and ONe collapse to a neutron star)
Spectral and photometric homogeneity supported this paradigm!
The B-light curve of 22 SNIA,
showing the similarity among
them (Cadonau ‘87)
Spectral homogeneity near the
maximum light &over the time
(Fillipenko)
However, differences among
individuals…
‘Fast’ & ‘Slow’ Barbon+’74
Pskovskii-Branch correlations’77
Phillips (1993; ApJ 413, L105)
A peculiar object is just a better observed object!
Everything able to explode eventually do it!
31%?
It makes sense to look for different
coexisting scenarios & explosion mechanisms
Scenarios leading
to a SNIa
Accreted matter:
H, He or C+O
# Everything able to explode eventually do it!
# At a first glance both scenarios SD & DD can coexist!
The presence of intermediate elements, the absence of important
amounts Fe-peak elements at maximum
The burning has to be subsonic (deflagration)
Detonations confined to regions with ρ ≤ 107 g/cm3
Deflagration and detonation can be combined:
In 1D
The equivalent in 3D
# Deflagration
also exist
# Delayed detonation
# Pulsational delayed detonation
Sub-Chandrasekhar models
CO-WD + He star
CO + He WD/He star
For dM/dt = 1 to 5 10-8 Mo/yr, He ignites off-center
before reaching the Chandrasekhar’s mass
ΔMHe = 0.05 – 0.1 Mo
He detonation occurs if ρ >2·106 g/cm3 and the T profile
is flat enough.
- He deflagration: Faint transients
- Single He detonation
- Double detonation
Off center detonations (E. Bravo et al ‘07)
(temperature)
Merging of CO + He WD
Dominguez et al
Inconsistent with observations
Sim + ‘10
He-detonation
Artificially suppressing
the effects of the outer layers
Guillochon et al’10
The detailed process of formation of the He envelope is
critical Guillochon et al’2010
Hot spots can trigger the detonation of He
C+He mixture is extremely flammable
Fink et al’11
Light curve properties
Origin of the Width-Luminosity relationship
(Kasen & Woosley’07; Woosley et al’07)
The models have the same kinetic energy,
but the Ni mass is substitued by IME
# It is a broad band effect.
The bolometric luminosity is not afected
# The luminosity at maximum:
L ~ f MNi exp(-tp/tNi)
# The width depends on the
diffusion time:
td ~ ΦNi κ1/2 M3/4 EK -1/4
The mass & distribution of Ni
is poorly known
Gamma-ray emission from 56Ni chain
Main properties of the ejecta
Model
56
DEF
0.5
Ni(Mo) V1Mo/109 EK(1051
cm/s
erg)
0.02
0.2
0.7
DEL
0.8
0.02
1.1
1.7
DET
0.7
0.04
1.1
1.5
SUB
0.6
0.01
0.6
1
Ni(Mo)
57
DET
SUB
DEL
Additionally: Each one of these models
rely on several parameters that introduce
further variety in the nucleosynthesis
products
Sub-Chandrasekhar models produce large
amounts of 44Ti
DEF
20d
D = 5 Mpc
•DEF only shows the continuum
•DEL,DET,SUB display strong lines
•56Ni still present
•56Ni & 56 Co prominent in SUB/DET
DET
DEL
DEF
SUB
Spectral evolution for:
•Deflagration
•Delayed detonation
•Detonation
•Sub-Chandrasekhar
Because of the presence of
low Z elements, continuum
extends to lower energies in
DEF & DEL
Gomez-Gomar, Isern, Jean’98
D = 5 Mpc
• 56Ni
lines have disappeared
• 122 - 136 keV 57Co lines appear
• the line intensity in DEL,DET, SUB ≈k· m of radioactive elements
• the energy cut-off of DEF is still below
60d
Spectral evolution for:
•Deflagration
•Delayed detonation
•Detonation
•Sub-Chandrasekhar
DET
DEL
DEF
SUB
D = 5 Mpc
• Optically thin
•Continuum dominated by annihilation
DET DEL
DEF SUB
120d
F(847)200d/F(158)max
DEF
8
DEL
2.2
SUB
1.3
DET
0.7
F (847)200 d / F (158) max 


56
56
Ni 
Ni 
tot
surface
Spectral evolution for:
•Deflagration
•Delayed detonation
•Detonation
•Sub-Chandrasekhar
Despite the distance
of SN2014J, the signal
is very weak!
Detection of
847 and 1248 keV lines
with 4.7 & 4,3 sigma
Mni = 0.63 Mo
Churazov et al 14, 15
SPI data
16 – 35 days a.e.
IBIS/ISGRI
Detected SNIa from 2003-07
Broad lines
~ 35 keV
Conclusions
#The classical problem still remain: which systems explode?
why they explode? How they explode?
# The first goal, to detect SNIa in gamma, accomplished
158 keV 56Ni & 847 , 1238 keV 56Co lines
# Lines are broad (~ 3%) and variable
#Gamma-rays allow to determine the total amount of 56Ni and
provide constraints to its distribution.
# A statistically representative sample of SNIa must be observed
# The ASTROGAM sensitivity is encouraging:
( ~10-5.06 cm-2 s-1 /35 keV ~ 3 x 10-7 cm-2 s-1 keV-1)