Elemental Composition and Distribution in Supernova Remnants : X-ray Spectroscopy

Anne DecourchelleService d'Astrophysique

CEA Saclay, France

I - X-ray morphology of the interaction region

II - Spatially resolved X-ray spectroscopy of the ejecta

III -Spectroscopy of the forward shock: particle acceleration

Collaborators:

G. Cassam-Chenai (PhD student, CEA Saclay)

J. Ballet, J.L. Sauvageot (CEA Saclay)

U. Hwang, R. Petre (NASA Goddard)

J. Hughes (Rutgers Univ.), D. Ellison (NCSU)

<----------Ejecta --------->

2 shocksInterstellar medium

Contact discontinuity

Young supernova remnants

SN material ejected at high velocity⇒ Heating of the ejecta and ISM

Progenitor/supernova:

-Nucleosynthesis products

-Element mixing-Density structure

Shock physics:-Non-equipartition between Te and Ti

-Particle acceleration

Interaction with the ambient medium:

-Rayleigh-Taylor instabilities

X-ray morphology of the interaction region

Remnants of type II

supernova

Cas A

E0102.2-7219(SMC)

Chandra

5 arcmin

Continuum 4-6 keVGotthelf et al. 2001, ApJ 552, L39

Color image: 0.6-1.6 keV, 1.6-1.2 keV, 2.2-7.5 keV

X (Chandra) / Visible (HST) / Radio (ATCA)Gaetz et al. 2000, ApJ 534, L47

Rayleigh-Taylor instabilities at the interface

40 arcsecHughes et al. 2000, ApJ 528,

L109

Cas A: D = 3.4 kpc

E0102.2-7219: D = 60 kpc

Type : SN Ia (white dwarf deflagration) Distance ~ 2.3 kpc

=> Production of heavy elements (O, Ne, Mg, Si, S, Ar, Ca, Fe)

8 arcmin

Remnants of type Ia supernova: Tycho (SN 1572)

X-ray Chandra 0.5-10 keVRadio VLA 6 cm

DeLaney et al., 2002, ApJ 580, 914

Kepler's Supernova Remnant (SN 1604): SN type ?

SN I a ? Light curve (Baade 1943) and Large distance above the Galactic planeSN II ? Circumstellar medium suggested by optical observations

Distance ~ 5 kpc

3 arcmin

Dwarkadas and Chevalier 1998, ApJ 497, 807

RADIUS

DENSITYprofile without particle accelerationExponential =>SN Ia Power law => SN II Constant profile=> plateau

Arnett 1988, ApJ 331, 377

Ejecta

Log R (cm)

RADIUS

Blondin and Ellison 2001, ApJ 560, 244Decourchelle, Ellison, Ballet 2000, ApJ 543, L57

Initial conditions for SN 1987A:

Interaction structuredepends on the

initial profiles of density

X-ray spatially resolved spectroscopy of the ejecta

Decourchelle et al., 2001, A&A 365, L218

Fe-L Mg S

ArCa

Fe-K

Fe XVII

Ne X Lyα

Mg XI Heα

Si XIII Heα

Si XIV Lyα

Ca

Fe Kα

SAr

Cassam-Chenai, Decourchelle, Ballet et al., 2003, A&A submitted

Kepler

Si

EPIC PN

EPIC MOS1EPIC MOS2

Mg S

ArCa

Fe-K

O Ne Fe

Fe-L

Tycho

Cas A

Willingale et al., 2002, A&A

Overall X-ray spectra obtained with XMM-

Newton

Si

ChandraCas A

Abundance ratios : core collapse of a 12 M starWillingale et al., 2002 A&A 381, 1039

Abundance maps

S/Si Ar/Si Ca/Si

Mapping heavy

elements

Heating of the gas

Particle acceleration

Interaction with the

interstellar medium

Fe K image FeL contours 4-6 keV

Fe L Si K

XMM-NEWTON

Kepler's SNR

Si K

Fe L

NorthSpatial distribution of silicon and iron

Si K

Fe LSouth

Fe L image and Si K contours

Cas A Tycho Kepler

Azimuthally averaged radial profile

Nucleosynthesis products

=> Asymmetrical line emission

=> Similar global repartition

except in particular locations.

Azimuthally averaged radial profile

Fe L image and Fe K contours

Cas A Tycho Kepler

Fe L

Fe K

Iron K EQW + Fe Lcontours

Chandra XMM-Newton XMM-Newton

Spatial distributionof Fe K and L lines

=> Higher temperature

toward the interior for Tycho

and Kepler

=> Constraints on the initial

density profile

Exponential

Constant density

Power law

Good overall correlation between the Si K and Fe L images

- except in particular knots in Tycho and Kepler

- except in the southeast of Cas A: inversion between Fe and Si layers

Fe K emission peaks distinctly at a lower radius than Fe L

-> higher temperature towards the reverse shock: constraints on the initial density profile

North/south asymmetry in the line emission:

Tycho: spatial variations of the elemental abundances or/and temperature

Kepler: spatial variations of the ambient density

Temperaturein models

X-ray spectroscopy of the forward shock: particle acceleration

Thermal component: kT ~ 3.5 keV and net ~ 4 1010 cm-3sNon-thermal component:RIM: 84 % of the 4-6 keV continuum, power law α ~ 2.2INSIDE: 11% of the 4-6 keV continuum, power law α > 4.5

=>width of the rim inconsistent with thermal emission=> X-ray synchrotron due to limited lifetime

of the ultrarelativistic electrons.

Vink and Laming 2003, ApJ 584, 758

VLA radioX-ray continuumChandra

(x 10)

Spectrum of the forward shock in Cas A

No emission line features !

Thermal interpretation:

kT = 2.1 keV and net = 108 cm-3s => strong ionization delay but problem with the morphology

Non-thermal interpretation:

X-ray power law: α ~ 2.8

Rolloff frequency: ν ~7 1016 Hz

=> maximum electron energies ~ 1-12 TeV

Hwang, Decourchelle, Holt, Petre 2002, ApJ 581, 1101

Broad band x-raysRadio 22cmX-ray Continuum

Chandra Chandra

Spectrum of the forward shock in Tycho

Shocked ejecta:=> thermal non ionization equilibrium emission

Shocked ambient medium:=> synchrotron emission using radio constraintsMaximum energy of accelerated electrons ~ 60 TeV

Shocked ejecta

Shocked ambient medium

XMM Continuum

Chandra Continuum

Cassam-Chenai, Decourchelle, Ballet, et al. 2003, A&A submitted

Spectrum of the forward shock in Kepler

SNRs with different characteristics :

- Forward shock traced by the high energy continuum emission in Tycho and Kepler and located close to the contact discontinuity unlike Cas A: in all cases, spectra and morphology indicates a nonthermal origin -> electrons up to energies of 1-60 TeV

- Discovery of particularly bright and hard continuum knots on the eastern and western edges of Tycho -> possible sites of efficient acceleration ?

- Different asymmetries in the line emission and in the high energy continuum:asymmetry of the explosion in Cas A, effect of abundances or/and of temperature in Tycho, density variation in the ambient medium for Kepler

- Iron K line at a smaller radius than iron L line : higher temperature towards the reverse shock -> constraints on the density profile

A DETAILED SPECTRAL ANALYSIS AT SMALL SCALE IS REQUIRED TO QUANTIFY ABUNDANCES/ TEMPERATURE BUT MODEL DEPENDENT

CONCLUSIONS