what do they look like? - lund observatory · what do they look like? pinning down the shape of...
TRANSCRIPT
Mattia Bulla
S t u a r t S i m , M a r k u s K r o m e r,
R ü d i g e r P a k m o r, I v o S e i t e n z a h l , S t e f a n T a u b e n b e r g e r, F r i e d r i c h
R ö p k e , Wo l f g a n g H i l l e b r a n d t
Whatdotheylooklike?
PinningdowntheshapeofTypeIasupernovae
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Type Ia supernovae
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Ø Thermonuclear explosions of carbon-oxygen white dwarfs
Credits: lbl.gov
No Hydrogen No Helium
Type Ia supernovae
Ø Thermonuclear explosions of carbon-oxygen white dwarfs in binary systems
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Type Ia supernovae
Ø Thermonuclear explosions of carbon-oxygen white dwarfs in binary systems, powered by the 56Ni − 56Co − 56Fe radioactive chain
Sollerman+2004
56Co decay
56Ni
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Log(Luminosity)
Days since maximum light
56Nimass≈0.6Msun
Type Ia supernovae
Ø Nature of the companion star?
SingleDegenerateSystem DoubleDegenerateSystem
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Type Ia supernova explosion models
Ø Explosion mechanism?
56Nimass≈0.6Msun
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Type Ia supernova explosion models
Ø Explosion mechanism?
Chandrasekhar-massmodelWhitedwarfmass≈1.4Msun
(Seitenzahl+2013)
56Nimass≈0.6Msun
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Type Ia supernova explosion models
Ø Explosion mechanism?
(Seitenzahl+2013)
56Nimass≈0.6Msun
Chandrasekhar-massmodelWhitedwarfmass≈1.4Msun
NonChandrasekhar-massmodelsWhitedwarfmass≈1.1Msun
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Type Ia supernova explosion models
Ø Explosion mechanism?
Violentmerger(Pakmor+2012)(Seitenzahl+2013)
56Nimass≈0.6Msun
Chandrasekhar-massmodelWhitedwarfmass≈1.4Msun
NonChandrasekhar-massmodelsWhitedwarfmass≈1.1Msun
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Type Ia supernova explosion models
Red:SN2011feBlack:Models Time
MAX
Röpke+2012
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Wavelength
Flux
What can we learn from geometry?
Chandrasekhar-massmodel Violentmerger
Ø Test and discriminate models based on their geometries
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
What can we learn from geometry?
Ø Polarisation in SNe arises from electron scattering processes
Θ
e−
Unpolarised
Linearly polarised Pol
Q λ0
Pol
Q
U
λ0
Pol
Q
U
λ0
Pol
Q λ0
Pol
Q
U
λ0
Pol
Q
U
λ0
Pcont=0
Pcont≠0
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
What can we learn from geometry?
Ø Polarisation in SNe arises from electron scattering processes
Θ
e−
Unpolarised
Linearly polarised
Ø Line scattering depolarises radiation
Pol
Q λ0
Pol
Q
U
λ0
Pol
Q
U
λ0
Pol
Q λ0
Pol
Q
U
λ0
Pol
Q
U
λ0
Pcont=0
Pline≠0
Pcont≠0
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Ø Polarisation peaks ~ 1 week before maximum light and then decreases
What can we learn from geometry?
Time
Wang+2003
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Wavelength
Flux
Pol (%)
Ø Polarisation peaks ~ 1 week before maximum light and then decreases Ø Continuum: ≤ 0.3 % Overall geometry: ~ spherically symmetric Ø Lines: up to 1-2 % Element distribution: stronger asymmetries
What can we learn from geometry?
SiIICaII
SiIICaII
SiIICaII
ConVnuum ConVnuum ConVnuum
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Wang+2003Wavelength
Flux
Pol (%)
What can we learn from geometry?
Ø Test and discriminate models based on their polarisation signatures
Chandrasekhar-massmodel Violentmerger
MB,SimandKromer2015
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Modelling polarisation
MB,Sim,Kromeretal.2016
MB,Sim,Pakmoretal.2016
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Wavelength
Flux
Pol (%)
Comparison with data: single objects
Chandrasekharmass
Ø Good agreement in the overall polarisation level
Ø Only real issue with calcium near-IR triplet
MB,Sim,Kromeretal.2016
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Wavelength
Flux
Pol (%)
Comparison with data: single objects
ViolentMerger Ø Too much polarised for Type Ia supernovae
MB,Sim,Pakmoretal.2016
Wavelength
Flux
Pol (%)
Comparison with data
Continuum
Wavelength
Flux
Pol (%)
Comparison with data: continuum polarization
Observed polarisation level:
Ø ≤0.3 per cent Ø Peaks ~ 1 week
before maximum Ø Decreases thereafter
MB,Sim,Kromeretal.2016
MB,Sim,Pakmoretal.2016
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Cont. Pol (%)
Days since maximum light
Wavelength
Flux
Pol (%)
Comparison with data
Si II 6355 line
Comparison with data: Si II 6355
MB,Sim,Kromeretal.2016
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Fraction (%)
Si II 6355 Polarisation (%)
Comparison with data: Si II 6355
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
MB,Sim,Kromeretal.2016Fraction (%)
Si II 6355 Polarisation (%)
Comparison with data: Si II 6355
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
MB,Sim,Kromeretal.2016Fraction (%)
Si II 6355 Polarisation (%)
Conclusions
Ø Polarisation provides a powerful way to discriminate between different explosion models of Type Ia supernovae
Ø The Chandrasekhar-mass model of Seitenzahl+2013
is in good agreement with data Ø The Violent Merger model of Pakmor+2012
is too strongly asymmetric to account for the low polarisation levels observed in Type Ia supernovae
Mattia Bulla Big Questions in Astrophysics, Transients workshop, Lund, 3 Apr 2017
Type Ia supernova explosion models
Mattia Bulla EO Meeting, 10 Nov 2016
RadiaVveTransfer
HydrodynamicExplosionModel
Comparisonwithdata
Pakmor+2012
−20
−10
0
10
20
v z(1
03km
s−1 )
Log Xi
C
−4 −3 −2 −1 0
O
−20 −10 0 10 20
vx (103 km s−1)
−20
−10
0
10
20
v z(1
03km
s−1 )
IMEs
−20 −10 0 10 20
vx (103 km s−1)
IGEs
Modelling polarisation
Mattia Bulla EO Meeting, 10 Nov 2016
Pol
Q λ0
Pol
Q
U
λ0
Pol
Q
U
λ0
Q≠0U≈0
MB,Sim,Pakmoretal2016a
Type Ia supernova explosion models
Mattia Bulla EO Meeting, 10 Nov 2016
Ø Explosion mechanism?
Chandrasekhar-massmodel NonChandrasekhar-massmodels
Violentmerger(Pakmor+2012)
DoubleDetonaVon(Fink+2010)
Whitedwarfmass≈1.4Msun Whitedwarfmass≈1.1Msun
Nickelmass≈0.6Msun
(Seitenzahl+2013)
Future
Mattia Bulla EO Meeting, 10 Nov 2016
Ø Polarisation signatures for additional Type Ia SN models
Future
Mattia Bulla EO Meeting, 10 Nov 2016
Ø Polarisation signatures for additional Type Ia SN models
Ø Studying individual spectral
features in more details
ü Correlations between spectroscopic and polarimetric properties to further discriminate between explosion models
Future
Mattia Bulla EO Meeting, 10 Nov 2016
C II
Ø Polarisation signatures for additional Type Ia SN models
Ø Studying individual spectral
features in more details
ü Correlations between spectroscopic and polarimetric properties to further discriminate between explosion models
ü Studying very weak spectral features (e.g. carbon lines)
Mattia Bulla EO Meeting, 10 Nov 2016
RadiaVveTransfer
HydrodynamicExplosionModel
Modelling polarisation
~ 1N
Modelling polarisation
Mattia Bulla EO Meeting, 10 Nov 2016
VirtualPackets
Modelling polarisation
Mattia Bulla EO Meeting, 10 Nov 2016
VirtualPackets
MB+2015
STOT = SjdPdΩ
ϑOBS,ϕOBS( ) ⋅exp −τ j( )$
%&'
()j∑
Modelling polarisation
Mattia Bulla EO Meeting, 10 Nov 2016
VirtualPackets
Scaaeringprobability
Probabilityofreachingtheobserver
Modelling polarisation
Mattia Bulla EO Meeting, 10 Nov 2016
Observer'
v(packets'
r(packet'
Observer'
v(packets' r(packet'
Modelling polarisation
λ
P(%)
Observer
Modelling polarisation
0.0
0.5
1.0
1.5Sc
aled
Flux
�20 �15 �10 �5 0 5 10Velocity (103 km s�1)
0.0
0.5
1.0
1.5
P(%
)
5600 5800 6000 6200Wavelength (A)
�30
0
30
60
90
c(d
eg)
l
rc
8000 km s�1
�0.5 0.0 0.5 1.0Q/I (%)
�0.5
0.0
0.5
1.0
1.5
U/I
(%)
2c
5.6
5.8
6.0
6.2
Wav
elen
gth
(103
A)
Modelling polarisation
0.5 1.0 1.5
∆m15 (mag)
0.0
0.5
1.0
1.5
2.0
PS
iII
(%)
SN 2001V
SN 1999by
SN 2005ke
SN 2004dt
SN 2006X
SN 2012fr
SN 2014J
Mattia Bulla EO Meeting, 10 Nov 2016
−20 −10 0 10 20
−20
−10
0
10
20
v z(1
03km
s−1 ) Si
−20 −10 0 10 20vr (103 km s−1)
Ca
−20 −10 0 10 20
IGEs
Mattia Bulla EO Meeting, 10 Nov 2016
−20 −10 0 10 20vx (103 km s−1)
−20
−10
0
10
20
v z(1
03km
s−1 )
Si
−20 −10 0 10 20vx (103 km s−1)
Ca
−20 −10 0 10 20vx (103 km s−1)
IGEs
Mattia Bulla EO Meeting, 10 Nov 2016
z
y
x
45°
45°
m1
m2
m3
m4
m5
45°
Mattia Bulla EO Meeting, 10 Nov 2016
5500 6000 6500 7000 7500 8000
Wavelength (A)
−0.4
0.0
0.4
UR
OT
/I
(%)
MC Noise
−0.4
0.0
0.4
0.8
QR
OT
/I
(%)
S IIλ5454λ5640-10000
Si IIλ5972-11000
Si IIλ6355-13000 O I λ7774
Si II λ7849Mg II λ7887
Ca II λ8498-26000
0.0
1.0
2.0
3.0I
(10−
11
erg
s−1
cm−
2A−
1)
2D D-DET
l1
Mattia Bulla EO Meeting, 10 Nov 2016
5500 6000 6500 7000 7500 8000
Wavelength (A)
−0.4
0.0
0.4
UR
OT
/I
(%)
−0.4
0.0
0.4
0.8
QR
OT
/I
(%)
S IIλ5454λ5640-10000
Si IIλ5972-11000
Si II λ6355-13000
O I λ7774Si II λ7849
Mg II λ7887
Ca IIλ8498-13000
0.0
1.0
2.0
3.0
I(1
0−
11
erg
s−1
cm−
2A−
1)
3D N100-DDT
n1
Mattia Bulla EO Meeting, 10 Nov 2016
0 1
−1
0
1
U/
I(%
)
5.9◦ m2
4 5 6 7 8
Wavelength (103 A)
0 1
-3.5◦ m3
0 1
6.4◦ m4
−1 0 1 2 3 4
Q / I (%)
−4
−3
−2
−1
0
1
U/
I(%
)
-17.8◦
Ca II
Si II
m1
−3 −2 −1 0 1 2
Q / I (%)
5.8◦ m5
Mattia Bulla EO Meeting, 10 Nov 2016
7000 7200 7400 7600 7800 8000 8200 8400
Wavelength (A)
−0.4
−0.2
0.0
0.2
0.4
0.6
0.8
QR
OT
/I
(%)
C A B
0.0
0.2
0.4
0.6
0.8
I(1
0−
11
erg
s−1
cm−
2A−
1)
−20 −10 0 10 20
A
Ca
Q+rotQ+
rot
−20 −10 0 10 20
v (103 km s−1)
B
Ca
Q−
rot
−20 −10 0 10 20−20
−10
0
10
20
v(1
03
km
s−1)
C
O
Q−
rot
−0.75 −0.50 −0.25 0.00Log N (scaled)
−20 −10 0 10 20
C
Mg
Q+rotQ+
rot
−20 −10 0 10 20
C
Si
Q+rotQ+
rot
Mattia Bulla EO Meeting, 10 Nov 2016
0
1
2
3
Sca
led
Fλ
SN 2004dt (scaled) −7 d
VM-11-09 m5 −7 d
4000 5000 6000 7000 8000
Wavelength (A)
0.0
0.5
1.0
1.5
2.0
2.5
P(%
)
0
1
2
3
SN 2004dt (scaled) +4 d
VM-11-09 m5 +4 d
4000 5000 6000 7000 8000
Wavelength (A)
0.0
0.5
1.0
1.5
2.0
2.5
Mattia Bulla EO Meeting, 10 Nov 2016
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
P(%
)
D-DET l2 −5 d N100-DDT n3 −5 d
-25 -20 -15 -10 -5 0
Velocity (103 km s−1)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
P(%
)
VM-11-09 m4 −5 d
-25 -20 -15 -10 -5 0
Velocity (103 km s−1)
Telluric
SN 2012fr −5 d