X-Ray Studies of Nucleosynthesis and Abundances in Supernova Remnants John P. Hughes

February 20, 2003February 20, 2003 Carnegie SymposumCarnegie Symposum 11

X-Ray Studies of X-Ray Studies of Nucleosynthesis and Nucleosynthesis and

Abundances in Supernova Abundances in Supernova RemnantsRemnants

John P. HughesJohn P. Hughes

Rutgers UniversityRutgers University


Why X-rays?Why X-rays? LyLy lines of all species from C (0.368 keV) to Zn (9.3 keV) lines of all species from C (0.368 keV) to Zn (9.3 keV) kT ~ 10kT ~ 1066 K to 10 K to 1088 K from shocks in ejecta and CSM/ISM K from shocks in ejecta and CSM/ISM

Si

Fe

S

Ar

Ca

W49B

ASCA


X-ray Emission/Atomic Processes X-ray Emission/Atomic Processes

Continuum emission – thermal bremsstrahlung:

Line emission:

Abundance of element

Z

Ionization fraction of ion i


Abundance Determination IssuesAbundance Determination Issues

Thermodynamic StateThermodynamic State– Nonequilibrium Ionization (NEI) (nNonequilibrium Ionization (NEI) (neet~10t~1055 cm cm-3-3 yr) yr)

– T, n evolution with time/radius (e.g., Sedov)T, n evolution with time/radius (e.g., Sedov)– Other effects:Other effects:

Heating/cooling in pure element ejectaHeating/cooling in pure element ejecta TTee/T/Tpp

Nonthermal particles (rates and excitation)Nonthermal particles (rates and excitation)

Absolute abundances (e.g., Si/H, O/H, Fe/H)Absolute abundances (e.g., Si/H, O/H, Fe/H)– Rely on assumption of H/He-dominated Rely on assumption of H/He-dominated

continuumcontinuum Relative abundances (e.g., Mg/Si, O/Fe)Relative abundances (e.g., Mg/Si, O/Fe)

– OK, if species have the same spatial distributionOK, if species have the same spatial distribution


Ejecta Mass Determination IssuesEjecta Mass Determination Issues

Volume estimationVolume estimation Clumping (reduces actual mass)Clumping (reduces actual mass) Distance (M~DDistance (M~D5/25/2)) Source of electronsSource of electrons

– Measure EM = nMeasure EM = neennIIVV

– Solar abundance: nSolar abundance: ne e ~ n~ nH H ~ n~ nFeFe/10/107.6-12 7.6-12 ~ ~ 25000n25000nFeFe

– Pure Fe: nPure Fe: ne e ~ 20n~ 20nFe Fe

– Inferred MInferred Mpure Fepure Fe /M /Msolarsolar ~ 35 ~ 35


Where do we find ejecta?Where do we find ejecta? Optical: SNRs with high velocity oxygen-rich featuresOptical: SNRs with high velocity oxygen-rich features Galactic: Cas A, G292.0+1.8, Puppis AGalactic: Cas A, G292.0+1.8, Puppis A LMC/SMC: N132D, E0540-69.3, E0102.2-72.2LMC/SMC: N132D, E0540-69.3, E0102.2-72.2 Other: an unresolved SNR in NGC 4449Other: an unresolved SNR in NGC 4449 Remnants of historical SNeRemnants of historical SNe e.g., SN1006, SN1572 (Tycho), SN1604 (Kepler)e.g., SN1006, SN1572 (Tycho), SN1604 (Kepler) Based on [Fe II] in absorption; X-ray spectraBased on [Fe II] in absorption; X-ray spectra Ejecta-dominated SNRs Ejecta-dominated SNRs e.g., W49B, G352.7-0.1, G337.2-0.7, G309.2-0.6e.g., W49B, G352.7-0.1, G337.2-0.7, G309.2-0.6 Based on X-ray spectra (mostly Based on X-ray spectra (mostly ASCAASCA)) Nearly all remnants up to ages of at least ~10,000 Nearly all remnants up to ages of at least ~10,000

yrs!!!yrs!!! N49, N63A, DEM71, N49B, and E0103-72.6N49, N63A, DEM71, N49B, and E0103-72.6 Based on Chandra spectro-imagingBased on Chandra spectro-imaging


Core Collapse SupernovaeCore Collapse Supernovae SN II, SN Ib/c (Zwicky & Baade 1934)SN II, SN Ib/c (Zwicky & Baade 1934)

– Massive stars that explode with (SN II) or Massive stars that explode with (SN II) or w/out (SN Ib/c) their H envelopesw/out (SN Ib/c) their H envelopes

– Photodisintegration of Fe, plus electron Photodisintegration of Fe, plus electron capture on nuclei, remove central P supportcapture on nuclei, remove central P support

– Core collapses, leading to NS or BHCore collapses, leading to NS or BH– Core stiffens, rebounds and drives an Core stiffens, rebounds and drives an

outward moving shockoutward moving shock– Neutrinos or jets needed to produce Neutrinos or jets needed to produce

explosionexplosion– Mean Rate ~ 1.3 SNUMean Rate ~ 1.3 SNU


Nucleosynthesis in CC SNeNucleosynthesis in CC SNe Hydrostatic nucleosynthesisHydrostatic nucleosynthesis

– During hydrostatic evolution of starDuring hydrostatic evolution of star– Builds up shells rich in H, He, C, O, and SiBuilds up shells rich in H, He, C, O, and Si– Amount of C, O, Ne, Mg ejected varies strongly Amount of C, O, Ne, Mg ejected varies strongly

with progenitor masswith progenitor mass Explosive nucleosynthesisExplosive nucleosynthesis

– Some mechanism drives a shock wave with Some mechanism drives a shock wave with 10105151+ erg through the Fe-core+ erg through the Fe-core

– Burning front T’s of ~10Burning front T’s of ~1099 K cause explosive O- K cause explosive O- and Si-burningand Si-burning

– Only affects the central parts of the star – outer Only affects the central parts of the star – outer layers retain their pre-SN compositionlayers retain their pre-SN composition


Explosive NucleosynthesisExplosive Nucleosynthesis

ProcessProcess T (10T (1099 K)K) Main ProductsMain Products

Explosive complete Si-Explosive complete Si-burning burning 5.05.0 ““Fe”, HeFe”, He

Explosive incomplete Si-Explosive incomplete Si-burningburning 4.04.0 Si, S, Fe, Ar, CaSi, S, Fe, Ar, Ca

Explosive O-burningExplosive O-burning 3.33.3 O, Si, S, Ar, CaO, Si, S, Ar, Ca

Explosive Ne/C-burningExplosive Ne/C-burning 1.21.2 O, Mg, Si, NeO, Mg, Si, Ne


Overturning Our View of Cas AOverturning Our View of Cas A

Hughes, Rakowski, Burrows, and Slane 2000, ApJL, 528, L109.


Cas A - Doppler Imaging by Cas A - Doppler Imaging by XMMXMM

Similar velocity structures Similar velocity structures in different linesin different lines– SE knots blueshiftedSE knots blueshifted– N knots redshiftedN knots redshifted– Tight correlation between Tight correlation between

Si and S velocitiesSi and S velocities Fe Fe

– Note velocity distribution in Note velocity distribution in NN

– Extends to more positive Extends to more positive velocities than Si or Svelocities than Si or S

Willingale et al 2002, A&A, 381, 1039


Cas A – 3D Ejecta ModelCas A – 3D Ejecta Model

Red: Si K

Green: S K

Blue: Fe K

Circle: Main shock

“Plane of the sky” “Rotated”

Fe-rich ejecta lies outside Si/S-rich ejecta


Oxygen-Rich SNR G292.0+1.8Oxygen-Rich SNR G292.0+1.8

Park et al 2001, ApJL, 564, L39



Ejecta

Rich in O, Ne, and Mg, some Si

[O]/[Ne] < 1

No Si-rich or Fe-rich ejecta



Normal Composition, CSM

Central bright bar – an axisymmetric stellar wind (Blondin et al 1996)

Thin, circumferential filaments enclose ejecta-dominated material – red/blue supergiant wind boundary


Thermonuclear SupernovaeThermonuclear Supernovae SN Ia (Hoyle & Fowler 1960)SN Ia (Hoyle & Fowler 1960)

– No hydrogen, a solar mass of No hydrogen, a solar mass of 5656Ni, some Ni, some intermediate mass elements (O, Mg, Si, S,…)intermediate mass elements (O, Mg, Si, S,…)

– Subsonic burning (deflagration) of approx. Subsonic burning (deflagration) of approx. one Chandrasekhar mass of degenerate C/Oone Chandrasekhar mass of degenerate C/O

– C-O white dwarf accreting H/He-rich gas C-O white dwarf accreting H/He-rich gas from a companionfrom a companion

– No compact remnantNo compact remnant– Mean rate ~ 0.3 SNUMean rate ~ 0.3 SNU


Identifying Remnants of SN Identifying Remnants of SN IaIa

Balmer-dominated SNRs Balmer-dominated SNRs (partially neutral ISM)(partially neutral ISM)

Ejecta abundances (Si and Ejecta abundances (Si and Fe rich, poor in O and Ne)Fe rich, poor in O and Ne)

Remnant structure (uniform Remnant structure (uniform ISM, “smoother” ejecta, little ISM, “smoother” ejecta, little spectral variation)spectral variation)

Tycho

E0509-67.5


SN Ia Spectra and SN Ia Spectra and AbundancesAbundances

W7: Nomoto et al 1984, Thielemann et al 1993

WDD1: Iwamoto et al 1999

NEI fit: Warren et al 2003

Comparison to models O, Ne, Mg: relatively low Si, S, Ar, Ca: consistent Fe: very low (<0.1)

Other spectral results Fe: co-spatial with Si, but hotter and lower net


ISM Abundances of the LMCISM Abundances of the LMC

Using SNRs as a probe of the ISMUsing SNRs as a probe of the ISM 7 SNRs, ages from 2,000 yr to 20,000 7 SNRs, ages from 2,000 yr to 20,000

yryr Data from Data from ASCAASCA Spectra calculated for evolutionary Spectra calculated for evolutionary

models (Sedov solution)models (Sedov solution)– spatial variationspatial variation– temporal variationtemporal variation


LMC SNRs: Integrated AbundancesLMC SNRs: Integrated AbundancesFrom fits to ASCA global X-ray spectra of 7 evolved LMC

remnants

Hughes, Hayashi, & Koyama 1998, ApJ, 505, 732

N49BDEM L71


LMC Metal AbundancesLMC Metal Abundances

HHK95: ASCA X-ray SNRs

Duf84: UV/Optical spectra H II regions (Dufour 1984)

RD92: F supergiants (Mg, Si, Fe) (Russell & Bessel 1989)

H II regions, SNRs (O, Ne, S) (Russell & Dopita 1990)

SpecieSpeciess

HHK98HHK98 Duf84Duf84 RD92RD92

OO 8.21(7)8.21(7) 8.43(8)8.43(8) 8.35(6)8.35(6)

NeNe 7.55(8)7.55(8) 7.64(107.64(10))

7.61(5)7.61(5)

MgMg 7.08(7)7.08(7) . . .. . . 7.47(137.47(13))

SiSi 7.04(8)7.04(8) . . .. . . ~7.8~7.8

SS 6.77(13)6.77(13) 6.85(116.85(11))

6.70(9)6.70(9)

FeFe 7.01(11)7.01(11) . . .. . . 7.23(147.23(14))


DEM L71DEM L71 Middle-aged SNRMiddle-aged SNR

– 36” (8.7 pc) in radius36” (8.7 pc) in radius– 4,000 yrs old4,000 yrs old

Rims: LMC compositionRims: LMC composition Core: [Fe]/[O] > 5 times solarCore: [Fe]/[O] > 5 times solar Ejecta mass: 1.5 MEjecta mass: 1.5 Msunsun

Hughes, Ghavamian, Rakowski, & Slane 2003, ApJ, 582, L95

SN Ia ejecta


N49BN49B Middle-aged SNRMiddle-aged SNR

– 80” (19 pc) in radius80” (19 pc) in radius– 5000-10,000 yrs old5000-10,000 yrs old

Bright and faint rimsBright and faint rims– LMC compositionLMC composition– ISM density varies by x10ISM density varies by x10

EjectaEjecta– Revealed by equivalent-width Revealed by equivalent-width

mapsmaps– Mg & Si rich, no strong O or NeMg & Si rich, no strong O or Ne

Park, Hughes, Slane, Burrows, Garmire, & Nousek 2003, ApJ, submitted.


SNR 0103-72.6SNR 0103-72.6 Middle-aged SNRMiddle-aged SNR

– 87” (25 pc) in radius87” (25 pc) in radius– >10,000 yrs old (?)>10,000 yrs old (?)

Circular rimCircular rim– SMC compositionSMC composition

Central bright regionCentral bright region– O, Ne, Mg, Si-rich ejectaO, Ne, Mg, Si-rich ejecta– No Fe enhancementNo Fe enhancement

Park, et al 2003, ApJ, in prep.


SummarySummary Core Collapse SNeCore Collapse SNe

– Cas ACas A X-ray ejecta dominated by Si, S, and FeX-ray ejecta dominated by Si, S, and Fe

– explosive nucleosynthesisexplosive nucleosynthesis

Extensive mixing and overturning of ejecta layersExtensive mixing and overturning of ejecta layers

– G292.0+1.8G292.0+1.8 X-ray ejecta dominated by O, Ne, and Mg (no Fe)X-ray ejecta dominated by O, Ne, and Mg (no Fe) Ambient medium strongly modified by progenitorAmbient medium strongly modified by progenitor Contains “normal” young pulsar and its wind nebulaContains “normal” young pulsar and its wind nebula

Highly Structured Ejecta/Environment


SummarySummary Thermonuclear SNe (Tycho, E0509-67.5)Thermonuclear SNe (Tycho, E0509-67.5)

– X-ray ejecta dominated by Si, S, and FeX-ray ejecta dominated by Si, S, and Fe– Stratification (most of the Fe core Stratification (most of the Fe core

unshocked)unshocked)– Fe: higher kT, lower nFe: higher kT, lower neet – due to:t – due to:

evolution (ejecta density profile)evolution (ejecta density profile) radioactivityradioactivity

– Ejecta relatively smooth and symmetricEjecta relatively smooth and symmetric only factor of 2 intensity variationsonly factor of 2 intensity variations little spectral variationlittle spectral variation few (one or two) clumps of Fe-rich ejectafew (one or two) clumps of Fe-rich ejecta


SummarySummary Evolved LMC SNRsEvolved LMC SNRs

– Global X-ray abundances consistent with Global X-ray abundances consistent with optical/UV valuesoptical/UV values

– Individual SNRs show obvious signs of ejectaIndividual SNRs show obvious signs of ejecta DEM L71: 4,000 yrs, Si and Fe-rich SN Ia ejectaDEM L71: 4,000 yrs, Si and Fe-rich SN Ia ejecta N49B: 5,000-10,000 yrs, Mg and Si-rich ejectaN49B: 5,000-10,000 yrs, Mg and Si-rich ejecta E0103-72.6: 10,000+ yrs, O, Ne, and Mg-rich E0103-72.6: 10,000+ yrs, O, Ne, and Mg-rich

ejectaejecta

Issues for nucleosynthesis modelsIssues for nucleosynthesis models– O/Ne ratio < 1 (G292.0+1.8)O/Ne ratio < 1 (G292.0+1.8)– O,Ne/Mg << 1 (N49B)O,Ne/Mg << 1 (N49B)


THE ENDTHE END


SN Ia Spectra and SN Ia Spectra and AbundancesAbundances


Properties of DEM L71 EjectaProperties of DEM L71 Ejecta Outer rim: lowered abundances, ~0.2 solar (LMC ISM)Outer rim: lowered abundances, ~0.2 solar (LMC ISM) Core: enhanced Fe abundance, [Fe]/[O] > 5 times solar (ejecta)Core: enhanced Fe abundance, [Fe]/[O] > 5 times solar (ejecta) Thick elliptical shell, 32” by 40” across (3.9 pc by 4.8 pc)Thick elliptical shell, 32” by 40” across (3.9 pc by 4.8 pc) Dynamical mass estimate Dynamical mass estimate

r’ ~ 3.0Mej = 1.1 Mch (n/0.5 cm-3)

Wang & Chevalier 2001

EM mass estimateEM mass estimate

EM ~ ne nFe VMFe < 2 Msun

Main error: source of Main error: source of electronselectrons

Fe-rich, low mass SN Ia


N63AN63A Middle-aged SNRMiddle-aged SNR

– 34” (8.2 pc) in radius34” (8.2 pc) in radius– 2000-5000 yrs old2000-5000 yrs old– 22ndnd brightest LMC SNR brightest LMC SNR

““Crescent”-shaped featuresCrescent”-shaped features– Similar to features in VelaSimilar to features in Vela– Clumps of high speed Clumps of high speed

ejectaejecta– Not ejecta dominatedNot ejecta dominated

Triangular hole Triangular hole – X-ray absorptionX-ray absorption– Approx. 450 solar mass Approx. 450 solar mass

cloudcloud– On near sideOn near side

No PSR or PWNNo PSR or PWN– LLXX < 4x10 < 4x103434 erg s erg s-1-1Warren, Hughes, & Slane, ApJ, in press (20 Jan

2003)

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X-Ray Studies of Nucleosynthesis and Abundances in Supernova Remnants John P. Hughes