Don Warren – 31 Oct 2013 – Kyoto SN conf.

Three-dimensional numericalinvestigations of themorphology of Type Ia SNRs
Don Warren
North Carolina State University

Anything without citation isfrom Warren & Blondin (2013)

Don Warren – 31 Oct 2013 – Kyoto SN conf.

現在地
You are here

Thanks to W. Hillebrandt!

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Outline• Motivation• Numerical model / setup• Output• Implications for Tycho’s SNR & SNR 1006
• Conclusions

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Motivation• X-ray images of Tycho’s SNR and SN 1006 showlots of structure. Can simple hydrodynamics do
this, or do we need more physics?
Tycho’s SNR

SN 1006

Warren+ (2005)

CassamCassamChenai+Chenai+ (2008)

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Motivation• Points of interest:• Ejecta structures in central
regions• Close proximity of ejecta to
forward shock• Knots of ejecta ahead offorward shock?
• Can we infer dynamical age ofboth SNRs?

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Numerical model• Used exponential radial
density profile(Dwarkadas & Chevalier 1998)• Swept out across full4π steradians using“Yin-Yang” grid(Kageyama & Sato 2004)

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Numerical model• 3-D grid size
180 zones
360 zones(r x θ x ϕ x YY): 360 x 360 x 1080 x 2• Tracked ionization timescale andejecta fraction
540 zones

900 zones• To approximate efficiency of CR acceleration, ran
three different simulations with differing
adiabatic indices: γeff = 5/3, γeff = 4/3, & γeff = 6/5(c.f. Blondin & Ellison 2001)

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Brief aside• 2-D runs showed 3 “epochs” regarding fluid
instabilities like R-T fingers:• Growth• Saturation• “Freeze-out”• Saturation period very important to our results,
so need to start early enough to reach it(one big difference between our paper andOrlando+ 2012)

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Brief aside• Initially smooth ejecta
generates all structures
to follow

NOT smallThanks to A. Wongwathanarat
Wongwathanarat!

• Effect of saturation: initialinstability seed irrelevant(for small initial perturbations)Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• γ = 5/3 run at t = 0.12

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• γ = 5/3 run at t = 0.75

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• γ = 5/3 run at t = 2.0

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• γ = 4/3 run at t = 2.0

Don Warren – 31 Oct 2013 – Kyoto SN conf.

OutputThanks to F. Winkler!

• γ = 6/5 run at t = 2.0

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• To directly compare against observations, wealso generated line-of-sight projections• Ejecta contributes as n2 (i.e. thermal emission)• Shocked ISM contributes radio synchrotron (soshocked ISM region broader than for X-raysynchrotron)

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• More images: γ = 5/3 run at t = 0.12

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• More images: γ = 5/3 run at t = 0.75

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• More images: γ = 5/3 run at t = 2.0

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• More images: γ = 4/3 run at t = 2.0

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• More images: γ = 6/5 run at t = 2.0

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• Key results:• Smooth ejecta can generate structures seen inTycho and SN 1006 – no physics beyond fluid
instabilities needed• Long simulation duration washes out small
initial instabilities• Remnants look very different at different
times, or with different compressibilities

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• Key results:• Increase age  increase size of RT structures• Change γ  change shape of RT structures• Decrease γ  make observed forward shock
filamentary• Decrease γ  dramatically reduce separation
between ejecta and forward shock• Hydrodynamics simulations give amazingly
pretty results

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• Ejecta knots ahead of forward shock is projection
effect combined with faint forward shock

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Output• Haven’t mentioned
ionization age yet• Instituting minimum τfor emission excludes
freshly shocked ejecta• Changes location &shape of reverse shock

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Implications for Tycho & SN1006• Ejecta structures larger in Tycho
than SN1006; larger dynamical
age for Tycho?
• Also, exponential model governedby 3 parameters – Me/MCh, E51,
and n0. Can we determine those?

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Implications for Tycho & SN1006• Methods available to determine these quantities:• Shock separation• Fluid/shock velocities• (Mostly) known distance/size information

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Implications for Tycho & SN1006• Ratio RRS/RCD for Tycho with (good) assumptionthat γ = 5/3 for ejecta gives estimate of t = 1.6• Can also use RRS/RFS (as in Warren+ 2005), but
requires extra assumption about compressibilityof material at forward shock• Assuming γFS ≥ 4/3 also gives t = 1.6

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Implications for Tycho & SN1006• SN1006 reverse shock speed of 7026 km/s
(Hamilton+ 2007) suggests t = 1.0• Tycho Fe Kα line speed of 4000 km/s (Hayato+ 2010)
suggests t = 1.1• Tycho ejecta expansion velocity of 4700 km/s
(Hayato+ 2010) suggests t = 1.0• Mystery: Tycho’s velocities and radial profile
each internally consistent, but don’t mutuallyagree

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Implications for Tycho & SN1006• For SN1006 have goodidea of distance, 2.18
kpc (Winkler+ 2003)• Angular size meansr = 9.19 pc• Best estimate:n0 = 0.019, E51 = 1.4(or n0 = 0.03, E51 = 2.1
if Me/MCh = 1.5)

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Implications for Tycho & SN1006• With n0 = 0.019, E51 = 1.4 and Me/MCh = 1,
dynamical age of SN1006 is t = 1.3• Measured RCD/RFS gives γeff ≈ 6/5• Less information for Tycho, but best guess is thatt = 1.0 and γeff slightly higher than 4/3• Reason for larger ejecta structures unclear

Don Warren – 31 Oct 2013 – Kyoto SN conf.

Conclusions• Morphology of Tycho & SN 1006 consistent withsignificant energy loss to CRs at forward shock• Smooth ejecta sufficient to generate observed
ejecta, forward shock structures• Dynamical ages of Tycho, SN 1006 both ≈ 1, butevidence for Tycho inconsistent• Much work to be done on both remnants

Don Warren – 31 Oct 2013 – Kyoto SN conf.