High Resolution X-ray Spectroscopy of SN 1006 X-ray Diagnostics of Astrophysical Plasmas Jacco Vink (SRON Nat. Inst. for Space Research) Cambridge Ma,

High Resolution X-ray Spectroscopy of SN 1006 X-ray Diagnostics of Astrophysical Plasmas Jacco Vink (SRON Nat. Inst. for Space Research) Cambridge Ma, Nov.

2004

Jacco Vink SRON National Institute for Space

ResearchThe Netherlands

High Resolution X-ray Spectroscopy

of

SN 1006


2004

Supernova Remnant & Plasma Physics

X-rays from SNRs are interesting for many reasons:● Studying the supernova phenomenon: - nucleosynthesis (bulk mass visible in X-rays, alpha elements) - explosion energy and asymmetries● Studying the interaction with the CSM/ISM● Studying plasma/shock physics: - high Mach number collisionless shocks - cosmic ray acceleration (prime sources up to 1015 eV?) - influence of cosmic rays on plasma (energy drain) - physics of hot, thin plasmas● Knowledge of plasma physics is a prerequisite for point 1


2004

Physics of SNR Plasmas● Plasmas are very tenuous, typically 1 cm-3

● SNR plasma are young ~10 – 50000 yr● Result: number of collisions between particles has been low!● Two main consequences:

- Plasmas are generally not in ionization equilibrium (it is in the process of being ionized) electron temperature and ionization out of synch! presence of satellite lines/inner shell ionization (ions in low ionization states/electrons energetic enough to knock out K-shell electron, while L, M shell electrons present)

- Plasma constituents may not be in temperature equilibrium● Important question: How come the plasma is heated at the shock front in the 1st place? Answer: plasma waves


2004

Non-Equilibrium Ionization (NEI)

log net = 12

11

10

9

Collision Ionization Equilibrium

NEI

SN 1006 Tycho

(oxygen)

Cas A

He-like


2004

Temperature Non-equilibrationSimplified plane parallel shock model, no equilibration:

Electrons

Protons

Question: Is collisionless heating accompanied byinstantaneous temperature equilibration (Te=Tp), or not?

For strong shock,neglecting cosmic raysinks:

kTi= 2(γ-1)(γ+1)-2 mi

vs2

= 3/16 mi vs2

(for γ =5/3)


2004

● young (~1000 yr) and low density (0.1 ions/cc)

ionization and equilibration scale with net

for SN 1006 ~ 3 x 109 cm-3s cf Cas A net > 1011 cm-3s

(ionization and temperature equilibrium net >

1012 cm-3s)

● Optical/ UV spectroscopy indicates temperature non-equilibration (Laming et al. 1996; Ghavamian et al 2002)● High Mach shock: >3000 km/s● Interesting historical, supernova remnant

Why SN1006?


2004

SN 1006 aka G327.6+14.6 (NB high latitude!):● bright (<-6 mag) “ guest star” in AD 1006 recorded in Middle East, Asia & Europe● likely to be Type Ia (but lack of observed Fe) ● distance 2.1 kpc (Ghavamian et al. 2002, Winkler et al.

2002)

● 30 arcmin diameter ● Average velocity 9375 km/s● Absorption column: NH ~7 x 1020 cm-2

● First shell remnant for which X-ray synchrotron emission was established (Koyama et al. 1995)

SN 1006 some background


2004

XMM-Newton's Reflection Grating Specrometers

(RGS)

- Three telescopes- Two gratings- No slit, spectral degradation: Δλ = 0.124( Δφ/1') Å


2004

Target

Knot size < 1 arcmin (0.4 arcmin FWHM) Spectral resolution for bright lines e.g OVII (~22Å): > 1/170

Observational Strategy


2004

RGS SpectrumO VII He α(triplet)

NVI He α(triplet)

NVI He β

NVI He γ,δ?! O VII He βOVIII Lyα

He γ

He δ,ε.. Ne VI/VII

N VIILy β

NB No bright Fe XVII lines(e.g. @15.0 Å)


2004

Low charge state of neon

Ne Kα (RGS 2 order 1)measured centroid 13.78 +/- 0.06 Å

cf Ne IX w : 13.44 Å, z :13.70 ÅSo not in Ne IX like state or unusually large f/r ratio


2004

Single temperature NEI model

OVII

Ne MgSi

OVII/O VIII

● net = 2.4 x109 cm-

3s● kTe = 1.5 ±0.2 keV● OVII dominated● Si ab. > 2 x solar

EPIC (CCD) spectra

Si Ka

Kα lines support low ionization parameter: Mg 1.33 ± 0.01 keV (cf. 1.35 keV MgXI)Si 1.80 ±0.01 keV (vs 1.85 keV Si XIV)


2004

Constraining NEI


2004

The OVII Thermal Broadening

No rapid equilibration of electron, proton

and oxygen temperature!!

Results on line dispersion :(21.3 - 22.5 Å, Chandra profile)

σE = 3.4±0.5 eV

kTOVII = 528 ± 150 keV (6x109 K)

vs ~ 4000 km/s

Statistical confidence : 6.5–9.8 σ


2004

OVII higher order lines

Fits well withn > 2 to n=1 intensities followingoscillator strengths

Dominated byHe α (some Lyα)He β/He α = 0.18expected 0.20

OVII G-ratio ~ 1


2004

The Spectrum of the Eastern RimHopeless for the RGS or perhaps not?

Pointing


2004

O VII triplet spectrumShifted

Over prediction

● Best fit shell velocity: 6010 ± 1227 km/s (90% conf)● Foreground shell dominates (~65%)● No large thermal broadening required● Inferred He-triplet ratio: G ~ 0.9

The Shell Velocity of SN 1006


2004

O VII He-like triplet

Based on rates calculated by M. Gu


2004

Summary● XMM's RGS allows high resolution spectroscopy of

~1 arcmin sized objects, or larger if small details are present● Many lines resolved that cannot be seen in CCD spectra, e.g. N VI,O VII n=4,5,6 -> n=1● No evidence for FeL lines, due to low ionization● Plasma far out of ionization equilibration: net ~ 2 x 109

cm-3s● CCD/RGS spectra: K line not always from He-like ionization state (Ne, Mg, Si), but due to inner shell processes ● Slow temp. equilibration of electrons and ions in NW: kTe ~ 1.5 keV and kTOVII ~ 500 keV● Evidence for 6000 km/s shell velocity in East

Results published in:J. Vink, J.M. Laming, M.F. Gu, A. Rasmussen, J. S. KaastraAstrophysical Journal Letters 587, L31 (2003)


2004

Ne He α

OVII He γ,δ,..

OVII Heα

OVII Heβ, OVIII Ly α

NVI Heβ, NVII Ly α Other?NVI Heα

(CVI Lyβ)

NB no bright Fe lines!

RGS SpectraPulse height (energy)

Dispersion (wavelength)

(Expected Fe XVII)

Documents

High Resolution X-ray Spectroscopy of SN 1006 X-ray Diagnostics of Astrophysical Plasmas Jacco Vink (SRON Nat. Inst. for Space Research) Cambridge Ma,