what do they look like? - lund observatory · what do they look like? pinning down the shape of...

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


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


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


Log(Luminosity)

Days since maximum light

56Nimass≈0.6Msun

Type Ia supernovae

Ø  Nature of the companion star?

SingleDegenerateSystem DoubleDegenerateSystem


Type Ia supernova explosion models

Ø  Explosion mechanism?

56Nimass≈0.6Msun




Chandrasekhar-massmodelWhitedwarfmass≈1.4Msun

(Seitenzahl+2013)

56Nimass≈0.6Msun




(Seitenzahl+2013)

56Nimass≈0.6Msun


NonChandrasekhar-massmodelsWhitedwarfmass≈1.1Msun




Violentmerger(Pakmor+2012)(Seitenzahl+2013)

56Nimass≈0.6Msun


NonChandrasekhar-massmodelsWhitedwarfmass≈1.1Msun



Red:SN2011feBlack:Models Time

MAX

Röpke+2012


Wavelength

Flux

What can we learn from geometry?

Chandrasekhar-massmodel Violentmerger

Ø  Test and discriminate models based on their geometries



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



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


Ø  Polarisation peaks ~ 1 week before maximum light and then decreases


Time

Wang+2003


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


SiIICaII

SiIICaII

SiIICaII

ConVnuum ConVnuum ConVnuum


Wang+2003Wavelength

Flux

Pol (%)


Ø  Test and discriminate models based on their polarisation signatures

Chandrasekhar-massmodel Violentmerger

MB,SimandKromer2015


Modelling polarisation

MB,Sim,Kromeretal.2016

MB,Sim,Pakmoretal.2016


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



Wavelength

Flux

Pol (%)

Comparison with data: single objects

ViolentMerger Ø  Too much polarised for Type Ia supernovae


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




Cont. Pol (%)

Days since maximum light

Wavelength

Flux

Pol (%)

Comparison with data

Si II 6355 line

Comparison with data: Si II 6355



Fraction (%)

Si II 6355 Polarisation (%)

Comparison with data: Si II 6355


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 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



Pol

Q λ0

Pol

Q

U

λ0

Pol

Q

U

λ0

Q≠0U≈0

MB,Sim,Pakmoretal2016a




Chandrasekhar-massmodel NonChandrasekhar-massmodels

Violentmerger(Pakmor+2012)

DoubleDetonaVon(Fink+2010)

Whitedwarfmass≈1.4Msun Whitedwarfmass≈1.1Msun

Nickelmass≈0.6Msun

(Seitenzahl+2013)

Future


Ø  Polarisation signatures for additional Type Ia SN models

Future



Ø  Studying individual spectral

features in more details

ü  Correlations between spectroscopic and polarimetric properties to further discriminate between explosion models

Future


C II


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)


RadiaVveTransfer

HydrodynamicExplosionModel


~ 1N



VirtualPackets



VirtualPackets

MB+2015

STOT = SjdPdΩ

ϑOBS,ϕOBS( ) ⋅exp −τ j( )$

%&'

()j∑



VirtualPackets

Scaaeringprobability

Probabilityofreachingtheobserver



Observer'

v(packets'

r(packet'

Observer'

v(packets' r(packet'


λ

P(%)

Observer


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)


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


−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


−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


z

y

x

45°

45°

m1

m2

m3

m4

m5

45°


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


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


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


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


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


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

what do they look like? - lund observatory · what do they look like? pinning down the shape of...

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