constraints on snia from their remnants: x-ray studies of the tycho snr john p. hughes

August 2006August 2006 JD09 IAU GA PragueJD09 IAU GA Prague 11

Constraints on SNIa from Constraints on SNIa from

Their Remnants: X-ray Their Remnants: X-ray

studies of the Tycho SNRstudies of the Tycho SNRJohn P. HughesJohn P. Hughes

Rutgers UniversityRutgers University

Collaborators: Jessica Warren, Carles Badenes, Gamil Cassam-

Chenai


Cassiopeia

Discovery of SN 1572

SN 1572 was first sighted in Korea and (probably) Spain on 6 November, SN 1572 was first sighted in Korea and (probably) Spain on 6 November, 1572, then shortly thereafter in China and elsewhere in Europe. It was 1572, then shortly thereafter in China and elsewhere in Europe. It was brighter than Venus (visible at noon for “those gifted with keen sight”).brighter than Venus (visible at noon for “those gifted with keen sight”).

Tycho Brahe noted the new star on the evening of 11 November, Tycho Brahe noted the new star on the evening of 11 November, carefully measured its position (his value is within ~2’ of the center of the carefully measured its position (his value is within ~2’ of the center of the remnant) and recorded its brightness until Mar 1574 when it became too remnant) and recorded its brightness until Mar 1574 when it became too faint to see.faint to see.

The remnant was discovered as a radio source in 1952 (also 3C10), The remnant was discovered as a radio source in 1952 (also 3C10), then as a faint set of Hthen as a faint set of H filaments, and lastly as an X-ray source in 1967. filaments, and lastly as an X-ray source in 1967.


A Modern View: Tycho’s SNR A Modern View: Tycho’s SNR Across WavebandsAcross Wavebands

VLA 1.4 GHz Chandra 0.5-7 keVOptical H

Current size ~ 8’ diameterOnly Balmer line optical emissionX-ray spectrum dominated by ejecta

Square root scale

Spitzer 24 mFe (red), Si (green), 4-6 keV

(blue)


What we knew prior to What we knew prior to ChandraChandra

Consistent with a Type Ia SN if most of the Consistent with a Type Ia SN if most of the Fe remains unshocked in the interior (i.e., Fe remains unshocked in the interior (i.e., ejecta stratified) ejecta stratified) (Hamilton, Sarazin, & Szymkowiak (Hamilton, Sarazin, & Szymkowiak 1986)1986)

There are Fe-rich blobs in SE There are Fe-rich blobs in SE (Vancura, Hughes, & (Vancura, Hughes, & Gorenstein 1995)Gorenstein 1995)

Fe-K emission peaks interior to Fe-L/Si-K Fe-K emission peaks interior to Fe-L/Si-K (Hwang & Gotthelf 1997) (Hwang & Gotthelf 1997)

Fe-K emission requires a distinct spectral Fe-K emission requires a distinct spectral component with higher kT and lower ncomponent with higher kT and lower neet t than Si & S than Si & S (Hwang, Hughes & Petre 1998) (Hwang, Hughes & Petre 1998)

X-ray expansion rate is ~0.124% yrX-ray expansion rate is ~0.124% yr-1-1, , somewhat higher than radio somewhat higher than radio (Hughes 2000)(Hughes 2000)


New Insights from Modeling INew Insights from Modeling I Radial variation in the X-ray spectrum Radial variation in the X-ray spectrum

due to kT gradient through ejectadue to kT gradient through ejecta– Invoke modest amount of collisionless Invoke modest amount of collisionless

electron heating (electron heating (~0.01-0.1) at the ~0.01-0.1) at the reverse shock reverse shock (Badenes, Borkowski, & Bravo 2005)(Badenes, Borkowski, & Bravo 2005)

=0.01=0.01

==minmin

=0.1=0.1

FeSi-S C-O


New Insights from Modeling IINew Insights from Modeling II X-ray spectral modeling of SN Ia remnants can X-ray spectral modeling of SN Ia remnants can

constrain explosion mechanism constrain explosion mechanism (Badenes et al. 2006)(Badenes et al. 2006)

– 1D hydro with realistic ejecta models evolved to age 1D hydro with realistic ejecta models evolved to age of Tycho (430 yrs) in uniform ambient mediumof Tycho (430 yrs) in uniform ambient medium

– Use XMM spectrum from west (avoid Fe blobs)Use XMM spectrum from west (avoid Fe blobs)

– Only 3 parameters: Only 3 parameters: AMAM, , , N, NHH

Delayed detonation – GOOD fit

Mixed 3D model – BAD fit


New Results from New Results from ChandraChandra Forward shock in Tycho shows Forward shock in Tycho shows

geometrically thin, spectrally geometrically thin, spectrally featureless rims featureless rims

(Hwang et al. 2002, Warren et al. 2005)(Hwang et al. 2002, Warren et al. 2005)4-6 keV continuum band

sqrt displaylinear display


Why Featureless?Why Featureless? Thermal interpretation untenable Thermal interpretation untenable (Warren et al. (Warren et al.

2005)2005)

– Low abundanceLow abundance Would require < 3% solar compositionWould require < 3% solar composition

– Low ionization timescale Low ionization timescale (Hwang et al. 2002)(Hwang et al. 2002)

Requires nRequires neet < 10t < 1088 cm cm-3-3 s or n s or nee ~ 0.05 cm ~ 0.05 cm-3-3

Inconsistent with nInconsistent with nee ~ 10 cm ~ 10 cm-3-3 from intensity from intensity

Nonthermal (synchrotron)Nonthermal (synchrotron)– Photon index (Photon index (pp = 2.7) consistent with = 2.7) consistent with GingaGinga

10-20 keV spectrum10-20 keV spectrum– Evidence for TeV energy electronsEvidence for TeV energy electrons– Similar to SN1006 only more intense!Similar to SN1006 only more intense!


Rim Morphology: Further Evidence Rim Morphology: Further Evidence for Relativistic Electrons at the Blast for Relativistic Electrons at the Blast

WaveWave Extract surface brightness Extract surface brightness

profiles and fit with thin profiles and fit with thin shell models (include shell models (include ChandraChandra PSF) PSF)– Thickness < 5”Thickness < 5”– B ~ 30-450 B ~ 30-450 GG Final nail: morphology of rim inconsistent Final nail: morphology of rim inconsistent

with thermal emission from shocked ambient with thermal emission from shocked ambient medium (from Badenes’ 1D hydro and medium (from Badenes’ 1D hydro and ionization model)ionization model)– Limits on thermal emission imply ambient density < 0.3 Limits on thermal emission imply ambient density < 0.3

cmcm-3 -3 (Cassam-Chenai et al 2006)(Cassam-Chenai et al 2006)

Thermal model only

Thermal model plus thin rim


Map of Thermal vs. nonthermal

Continuum-subtracted Fe-K

Locating the BW, CD, RS in Locating the BW, CD, RS in TychoTycho

Green contour defines Green contour defines contact discontinuity contact discontinuity (CD), as boundary (CD), as boundary between thermal and between thermal and nonthermal emissionnonthermal emission

Outermost edge Outermost edge of X-ray emission of X-ray emission defines blast defines blast wave (BW)wave (BW)

Reverse shock Reverse shock (RS) from shell (RS) from shell fits to Fe K imagefits to Fe K image

Broadband 0.5-7 keV


Locating the BW, CD, RS in Locating the BW, CD, RS in TychoTycho

Mean radii:Mean radii:– BW: 251” 1.0 (black)BW: 251” 1.0 (black)– CD: 241” 0.93 (green)CD: 241” 0.93 (green)– RS: 183” 0.72 (purple)RS: 183” 0.72 (purple)

Relative positions Relative positions constrain dynamical constrain dynamical state: inconsistent with state: inconsistent with shock hydro-modelsshock hydro-models

Problem: CD too close to BW Solution: CR acceleration

Insufficient pressure in relativistic electrons – large hadronic component required

Blondin & Ellison 2001


ChandraChandra View of Si/Fe in View of Si/Fe in TychoTycho

Hughes et al. 2006, in prep.

Broadband Chandra image

“Fe-rich” emission

Si-rich emission

1.8 keV (Si) to 0.8 keV (Fe) emission ratio

Examine spectra of six knots at breakout on rimSi-richFe-rich


Chandra Spectra of Tycho Chandra Spectra of Tycho Knots Knots

[Si/Fe]

[Si/Fe]

0.32

0.35

0.64

20

15

6

Single component fits, kT ~ 1-3 keV, net ~ 3x1010 cm-3 sSi abundances all > 2 x solar (confirmed ejecta knots)Factor of >60 range in [Si/Fe], but no pure Fe or Si knots

Fe-rich Si-rich


Origin of SN Ia Ejecta Clumps IOrigin of SN Ia Ejecta Clumps I

Clumps may originate in the region between Si+S and Fe rich zones A consequence of the nickel bubble effect? BUT WHY ONLY A SINGLE SUCH FE-RICH CLUMP?


Origin of SN Ia Ejecta Clumps IIOrigin of SN Ia Ejecta Clumps IIIgnition of the thermonuclear flame occurs near the star’s centerThe resulting hot bubble of Fe-rich “ash” is buoyantNot yet clear how many such bubbles are involvedHigh velocity, asymmetric Ca emission from Ia SNe (e.g., SN2001el)

Simulation of a buoyant bubble being sheared by Rayleigh-Taylor instabilities (from Flash Center at Chicago)

Is this a spark from the ignition of the SN Ia explosion that formed the Tycho SNR?

Would be a unique view of the SNIa ignition process!!


Tycho ScorecardTycho Scorecard Previous results confirmed/explainedPrevious results confirmed/explained

– Tycho is the remnant of a SN IaTycho is the remnant of a SN Ia Realistic SN Ia explosion models (~10Realistic SN Ia explosion models (~105151 ergs, ergs,

1.4 M1.4 Msunsun of compositionally-stratified ejecta, of compositionally-stratified ejecta, density & velocity profiles) describe the X-density & velocity profiles) describe the X-ray spectra, size, and age of Tycho.ray spectra, size, and age of Tycho.

– Fe-K peaks interior to Fe-L/Si-KFe-K peaks interior to Fe-L/Si-K Requires some collisionless electron heating Requires some collisionless electron heating

at reverse shockat reverse shock


Tycho ScorecardTycho Scorecard New findings (explained)New findings (explained)

– Spectrally featureless, geometrically-thin rims Spectrally featureless, geometrically-thin rims Synchrotron emission from relativistic electrons – Synchrotron emission from relativistic electrons –

evidence for diffusive shock accelerationevidence for diffusive shock acceleration Also present in Cas A, Kepler, SN1006, RCW 86, …Also present in Cas A, Kepler, SN1006, RCW 86, …

– Closeness of contact discontinuity to forward shockCloseness of contact discontinuity to forward shock Cosmic-ray modified dynamics – requires relativistic Cosmic-ray modified dynamics – requires relativistic

protons – strong evidence for the hadronic component of protons – strong evidence for the hadronic component of cosmic rayscosmic rays

Consequences:Consequences:– No measurements of forward shock temperature or No measurements of forward shock temperature or

ambient medium density from X-raysambient medium density from X-rays– Dynamical models that ignore CR acceleration Dynamical models that ignore CR acceleration

(e.g., Truelove & McKee 1999) now inadequate(e.g., Truelove & McKee 1999) now inadequate


Tycho ScorecardTycho Scorecard New findings (not yet fully explained)New findings (not yet fully explained)

– Single Fe-rich clump at rimSingle Fe-rich clump at rim A “spark” from the SN Ia ignition process ??A “spark” from the SN Ia ignition process ??

– Spatial variation in emission from low-Z Spatial variation in emission from low-Z (O, Ne, Mg) vs. high-Z (Si, S, Ar, Ca) (O, Ne, Mg) vs. high-Z (Si, S, Ar, Ca) species species (Warren 2006, PhD thesis; Warren & Hughes (Warren 2006, PhD thesis; Warren & Hughes 2006)2006)

Compositional inhomogeneity in SN Ia or an Compositional inhomogeneity in SN Ia or an excitation effect ??excitation effect ??

Spectra contain less (rim, west) or more (interior, east) emission below 0.7 keV

Low-Z (O, Ne, Mg)/High-Z (S, Ar, Ca)

[O/S] ~ 0.13 to 0.33


SN1006 SNR: Also a DDT? Carles Badenes Cefalú 14/06/06

19

➢ The thermal X-ray emission in SN1006 is also dominated by ejecta.

➢ Model DDTe (ρAM

=2x10-25 g.cm-3, β=0.1) + powerlaw + absorption.

➢ Work in progress, but DDT models are the only ones that work well so far...

O HeαO He

Ne HeαMg Heα

Si Heα

S Heα

Ar Heα

SN 1006 SNR. Top: Chandra image [Hughes et al. in prep.]. Left: Chandra spectrum [Badenes et al. in prep.]


THE ENDTHE END


Evidence for Type Ia originEvidence for Type Ia origin– Pure Balmer spectra Pure Balmer spectra (Kirshner & Chevalier 1978)(Kirshner & Chevalier 1978)

Partially neutral ambient mediumPartially neutral ambient medium

– No compact remnantNo compact remnant– X-ray spectrum X-ray spectrum (Hwang et al. 1998)(Hwang et al. 1998)

– X-ray structureX-ray structure Uniform ISM, “smoother” ejecta, modest Uniform ISM, “smoother” ejecta, modest

spectral variationsspectral variations

– 1.4 solar masses of ejecta 1.4 solar masses of ejecta (Hamilton et al. (Hamilton et al. 1986)1986)

What Type Of Explosion?What Type Of Explosion? Evidence for Type Ia originEvidence for Type Ia origin

– Light curveLight curve Based on historical records Based on historical records (Baade 1945, Ruiz-(Baade 1945, Ruiz-

Lapuenta 2004)Lapuenta 2004)


Principal Component AnalysisPrincipal Component Analysis

Spectra vary from Strong Fe-L (e.g., eastern blob) to Strong Si-K

Fe-rich/Si-rich

Spectra contain less (rim, west) or more (interior, east) emission below 0.7 keV

Low-Z (O, Ne, Mg)/High-Z (S, Ar, Ca)

Spectra vary from Line-dominated to Featureless

Thermal/Synchrotron

(Warren 2006, PhD thesis, Warren & Hughes (Warren 2006, PhD thesis, Warren & Hughes 2006)2006)


FinFin

constraints on snia from their remnants: x-ray studies of the tycho snr john p. hughes

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