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Cassiopea A

Cassiopea A. Age:  300 y Distance: 3.4 kpc Size: ~ 210 arcsec Average expansion (FMKs): 5290km/s. Cas A: Radio, IR. Radio. IR. Cas A: Chandra. Cas A: our work on Beppo SAX data. Broad-band spectrum .. LECS, MECS, HP, PDS 0.5 – 80 keV Imaging of spectral features ..

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Cassiopea A

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  1. Cassiopea A • Age: 300 y • Distance: 3.4 kpc • Size: ~210 arcsec • Average expansion (FMKs): 5290km/s

  2. Cas A: Radio, IR Radio IR

  3. Cas A: Chandra

  4. Cas A:our work on BeppoSAX data • Broad-band spectrum .. • LECS, MECS, HP, PDS • 0.5 – 80 keV • Imaging of spectral features .. • MECS, no deconvolution • Comparison of X-ray line and continuum morphology .. • MECS, deconvolution • Spatially resolved spectroscopy .. • MECS • deconvolution, data cube (X,Y,E)

  5. Cas A: obs. log Total net exp. time: 128.000 s Total n. of counts: 3.7 Mcts

  6. Intensity maps ( Fe K ) : Chandra BeppoSAX [Fe]

  7. Chandra

  8. Chandra:

  9. Spectral analysis:Fitting parameters • NEI (non-equilibrium ionization plasma) • NH : 0.9 – 1.7 E+22 • [M]: 0.02 – 20 x solar • kT • Net (ionization parameter): 6-12.5 • Power law • α : 2.95 (fixed) • Norm: computed assuming that the whole remnant contributes to the high energy component, with emissivity proportional to the MECS flux detected in each pixel. XMM: “the hard x-ray image and the hardness ratio indicate that” the 8.1-15keV “flux does not predominate in a few localized regions, but pervades the whole remnant in a distribution similar to the softer thermal component.”

  10. XMM Cas A: global spectrum XMM – EPIC (4-12 keV)

  11. Spectral analysis:results • Only one thermal component per pixel (previous global analysis: two th. comp.). This means that if two components are indeed present, they are spatially separated. • NH: consistent with previous results • kT: in most regions 1-2 keV, why? • Main shock unobserved, interacting with tenuous ISM • Reverse shock: a hydro-nonsense • Cold supersonic flow: azimuthal shocks?

  12. Spectral analysis:results • net: distribution clearly bimodal • 1) in density • 2) in shocking time • Case 1 more realistic: • Total emitting mass < 30 Msun • ISM => low density component • Ejecta => high density comp. • M(ISM)/M(EJ) < 0.1

  13. Abundances:Detections (out of the 182 pixels) and quality • [Si] 167 A: • [S] 164 A • [Ar] 106 B • [Ca] 90 C • [Fe] 105 A • [Ni] 49 C

  14. Abundances.Global overabundance factors by mass: Element (1) (2) [Si] 3.3 3.1 [S] 5.3 5.0 [Ar] 6.3 4.1 [Ca] 6.8 4.6 [Fe] 1.5 1.4 [Ni] 7.1 3.9 • We consider only pixels in which we detect the element • We consider also the contribution of all other pixels at solar value

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