1. August 2006JD09 IAU GA Prague1 Constraints on SNIa from Their Remnants: X-ray studies of the Tycho SNR John P. Hughes Rutgers University Collaborators: Jessica Warren, Carles Badenes, Gamil Cassam-Chenai

2. August 2006JD09 IAU GA Prague2 Cassiopeia Discovery of SN 1572 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 brighter than Venus (visible at noon for “those gifted with keen sight”). 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 brighter than Venus (visible at noon for “those gifted with keen sight”). 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 remnant) and recorded its brightness until Mar 1574 when it became too faint to see. 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 remnant) and recorded its brightness until Mar 1574 when it became too faint to see. The remnant was discovered as a radio source in 1952 (also 3C10), then as a faint set of H  filaments, and lastly as an X-ray source in 1967. The remnant was discovered as a radio source in 1952 (also 3C10), then as a faint set of H  filaments, and lastly as an X-ray source in 1967.

3. August 2006JD09 IAU GA Prague3 A Modern View: Tycho’s SNR Across Wavebands VLA 1.4 GHzChandra 0.5-7 keV Optical H  Current size ~ 8’ diameter Only Balmer line optical emission X-ray spectrum dominated by ejecta Square root scale Spitzer 24  m Fe (red), Si (green), 4-6 keV (blue)

4. August 2006JD09 IAU GA Prague4 What we knew prior to Chandra Consistent with a Type Ia SN if most of the Fe remains unshocked in the interior (i.e., ejecta stratified) (Hamilton, Sarazin, & Szymkowiak 1986) Consistent with a Type Ia SN if most of the Fe remains unshocked in the interior (i.e., ejecta stratified) (Hamilton, Sarazin, & Szymkowiak 1986) There are Fe-rich blobs in SE (Vancura, Hughes, & Gorenstein 1995) There are Fe-rich blobs in SE (Vancura, Hughes, & Gorenstein 1995) Fe-K emission peaks interior to Fe-L/Si-K (Hwang & Gotthelf 1997) Fe-K emission peaks interior to Fe-L/Si-K (Hwang & Gotthelf 1997) Fe-K emission requires a distinct spectral component with higher kT and lower n e t than Si & S (Hwang, Hughes & Petre 1998) Fe-K emission requires a distinct spectral component with higher kT and lower n e t than Si & S (Hwang, Hughes & Petre 1998) X-ray expansion rate is ~0.124% yr -1, somewhat higher than radio (Hughes 2000) X-ray expansion rate is ~0.124% yr -1, somewhat higher than radio (Hughes 2000)

5. August 2006JD09 IAU GA Prague5 New Insights from Modeling I Radial variation in the X-ray spectrum due to kT gradient through ejecta Radial variation in the X-ray spectrum due to kT gradient through ejecta –Invoke modest amount of collisionless electron heating (  ~0.01-0.1) at the reverse shock (Badenes, Borkowski, & Bravo 2005)  =0.01  =  min  =0.1 Fe Si-S C-O

6. August 2006JD09 IAU GA Prague6 New Insights from Modeling II X-ray spectral modeling of SN Ia remnants can constrain explosion mechanism (Badenes et al. 2006) X-ray spectral modeling of SN Ia remnants can constrain explosion mechanism (Badenes et al. 2006) –1D hydro with realistic ejecta models evolved to age of Tycho (430 yrs) in uniform ambient medium –Use XMM spectrum from west (avoid Fe blobs) –Only 3 parameters:  AM, , N H Delayed detonation – GOOD fit Mixed 3D model – BAD fit

7. August 2006JD09 IAU GA Prague7 New Results from Chandra Forward shock in Tycho shows geometrically thin, spectrally featureless rims Forward shock in Tycho shows geometrically thin, spectrally 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

8. August 2006JD09 IAU GA Prague8 Why Featureless? Thermal interpretation untenable (Warren et al. 2005) Thermal interpretation untenable (Warren et al. 2005) –Low abundance  Would require < 3% solar composition –Low ionization timescale (Hwang et al. 2002)  Requires n e t < 10 8 cm -3 s or n e ~ 0.05 cm -3  Inconsistent with n e ~ 10 cm -3 from intensity Nonthermal (synchrotron) Nonthermal (synchrotron) –Photon index (  p = 2.7) consistent with Ginga 10-20 keV spectrum –Evidence for TeV energy electrons –Similar to SN1006 only more intense!

9. August 2006JD09 IAU GA Prague9 Rim Morphology: Further Evidence for Relativistic Electrons at the Blast Wave Extract surface brightness profiles and fit with thin shell models (include Chandra PSF) Extract surface brightness profiles and fit with thin shell models (include Chandra PSF) –Thickness < 5” –B ~ 30-450  G Final nail: morphology of rim inconsistent with thermal emission from shocked ambient medium (from Badenes’ 1D hydro and ionization model) Final nail: morphology of rim inconsistent with thermal emission from shocked ambient medium (from Badenes’ 1D hydro and ionization model) –Limits on thermal emission imply ambient density < 0.3 cm -3 (Cassam-Chenai et al 2006) Thermal model only Thermal model plus thin rim

10. August 2006JD09 IAU GA Prague10 Map of Thermal vs. nonthermal Continuum-subtracted Fe-K Locating the BW, CD, RS in Tycho Green contour defines contact discontinuity (CD), as boundary between thermal and nonthermal emission Green contour defines contact discontinuity (CD), as boundary between thermal and nonthermal emission Outermost edge of X-ray emission defines blast wave (BW) Outermost edge of X-ray emission defines blast wave (BW) Reverse shock (RS) from shell fits to Fe K image Reverse shock (RS) from shell fits to Fe K image Broadband 0.5-7 keV

11. August 2006JD09 IAU GA Prague11 Locating the BW, CD, RS in Tycho Mean radii: Mean radii: –BW: 251” 1.0 (black) –CD: 241” 0.93 (green) –RS: 183” 0.72 (purple) Relative positions constrain dynamical state: inconsistent with shock hydro-models Relative positions constrain dynamical state: inconsistent with shock hydro-models Problem: CD too close to BW Solution: CR acceleration Insufficient pressure in relativistic electrons – large hadronic component required Blondin & Ellison 2001

12. August 2006JD09 IAU GA Prague12 Chandra View of Si/Fe in Tycho 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 rim Si-rich Fe-rich

13. August 2006JD09 IAU GA Prague13 Chandra Spectra of Tycho Knots [Si/Fe] 0.32 0.35 0.64 20 15 6 Single component fits, kT ~ 1-3 keV, n e t ~ 3x10 10 cm -3 s Si abundances all > 2 x solar (confirmed ejecta knots) Factor of >60 range in [Si/Fe], but no pure Fe or Si knots Fe-richSi-rich

14. August 2006JD09 IAU GA Prague14 Origin 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?

15. August 2006JD09 IAU GA Prague15 Origin of SN Ia Ejecta Clumps II Ignition of the thermonuclear flame occurs near the star’s center The resulting hot bubble of Fe-rich “ash” is buoyant Not yet clear how many such bubbles are involved High 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!!

16. August 2006JD09 IAU GA Prague16 Tycho Scorecard Previous results confirmed/explained Previous results confirmed/explained –Tycho is the remnant of a SN Ia  Realistic SN Ia explosion models (~10 51 ergs, 1.4 M sun of compositionally-stratified ejecta, density & velocity profiles) describe the X-ray spectra, size, and age of Tycho. –Fe-K peaks interior to Fe-L/Si-K  Requires some collisionless electron heating at reverse shock

17. August 2006JD09 IAU GA Prague17 Tycho Scorecard New findings (explained) New findings (explained) –Spectrally featureless, geometrically-thin rims  Synchrotron emission from relativistic electrons – evidence for diffusive shock acceleration  Also present in Cas A, Kepler, SN1006, RCW 86, … –Closeness of contact discontinuity to forward shock  Cosmic-ray modified dynamics – requires relativistic protons – strong evidence for the hadronic component of cosmic rays Consequences: Consequences: –No measurements of forward shock temperature or ambient medium density from X-rays –Dynamical models that ignore CR acceleration (e.g., Truelove & McKee 1999) now inadequate

18. August 2006JD09 IAU GA Prague18 Tycho Scorecard New findings (not yet fully explained) New findings (not yet fully explained) –Single Fe-rich clump at rim  A “spark” from the SN Ia ignition process ?? –Spatial variation in emission from low-Z (O, Ne, Mg) vs. high-Z (Si, S, Ar, Ca) species (Warren 2006, PhD thesis; Warren & Hughes 2006)  Compositional inhomogeneity in SN Ia or an 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

19. August 2006JD09 IAU GA Prague19 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 (ρ AM =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 He α O He  Ne He α Mg He α Si He α S He α Ar He α SN 1006 SNR. Top: Chandra image [Hughes et al. in prep.]. Left: Chandra spectrum [Badenes et al. in prep.]

20. August 2006JD09 IAU GA Prague20 THE END

21. August 2006JD09 IAU GA Prague21 Evidence for Type Ia origin Evidence for Type Ia origin –Pure Balmer spectra (Kirshner & Chevalier 1978)  Partially neutral ambient medium –No compact remnant –X-ray spectrum (Hwang et al. 1998) –X-ray structure  Uniform ISM, “smoother” ejecta, modest spectral variations –1.4 solar masses of ejecta (Hamilton et al. 1986) What Type Of Explosion? Evidence for Type Ia origin Evidence for Type Ia origin –Light curve  Based on historical records (Baade 1945, Ruiz-Lapuenta 2004)

22. August 2006JD09 IAU GA Prague22 Principal 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 2006)

23. August 2006JD09 IAU GA Prague23 Fin