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Shock-cloud interaction in the Vela SNR: the XMM-Newton view

Shock-cloud interaction in the Vela SNR: the XMM-Newton view. M. Miceli 1 , F. Bocchino 2 , A. Maggio 2 , F. Reale 1 1.Dipartimento di Scienze Fisiche ed Astronomiche, Universit à di Palermo 2. INAF-Osservatorio Astronomico G. S. Vaiana di Palermo. Low spatial resolution (> 5’).

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Shock-cloud interaction in the Vela SNR: the XMM-Newton view

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  1. Shock-cloud interaction in the Vela SNR: the XMM-Newton view M. Miceli1, F. Bocchino2, A. Maggio2, F. Reale1 1.Dipartimento di Scienze Fisiche ed Astronomiche, Università di Palermo 2. INAF-Osservatorio Astronomico G. S. Vaiana di Palermo

  2. Low spatial resolution (> 5’). Low Aeff. Low spectral resolution (E/DE < 2) Low Aeff. Geometry of the system? No detailed comparison between X-ray and optical emission. Difficulty in estimating the physical parameters of the plasma. Detecting NEI effects. Interaction between the blast-wave shock of a middle-aged SNR and the inhomogeneities of the ISM. The analysis of past X-ray observations left many open issues: Impossibility of unambiguously describing the physics of the shock-cloud interaction.

  3. Thedata • Guaranteed Time Observation. • Coordinates: a (2000)=8h35m44s; d (2000) = -42º35’29’’. • Exposure time: 26.8 ksec (PN); 31.1 ksec (MOS). • Mode: Extended Full Frame (PN); Large Window (MOS). • Filter: Medium.

  4. Our aims: • Describing the morphology of the ISM clouds (shape, dimension, spatial distribution…). • Obtaining information about the physical properties and the internal structure of the clouds. • Studying the dynamics and the evolution of the shock-cloud interaction. ROSAT All Sky Survey (0.2-2.4 keV)

  5. EPIC count rate images RegNE ~ 2.4 pc 0 cnt/s 7.210-5 0 cnt/s 10-4 FilD

  6. Comparison between X-ray and optical emission in the FilD region • Color coding: • Green: Ha emission • Violet: OIII emission • Red: X-ray contour levels (0.3-0.5 keV) Maximum X-ray contour levels are just outside the optical filament: the optical emission follows a path that grazes, without crossing, the brightest X-ray FilD regions.

  7. Regions selected for spectral analysis 0.3-2 keV • Color coding: • Black: FilD • Red: South-Western region • Blue: RegNE In each region the mean photon energy E has low fluctuations: DE/Eavg  0.04

  8. Spectral analysis Representative folded spectrum O/O= 1.0 ± 0.1 Ne/Ne = 1.7 ± 0.2 Fe/Fe = 0.39 ± 0.05 All spectra are well described by two MEKAL components

  9. TII (106 K) TI (106 K) cnt/s The values of the temperature of both components don’t show significant variations in the field of view.

  10. nII2LII (1017 cm-5) nI2LI (1017 cm-5) cnt/s For both components the product n2L (where n is the particle density and L is the extension along the line of sight) presents huge inhomogeneities in the field of view.

  11. Evolution of the shocked clouds n = 0.5  1.9 cm-3 T  3.0  106 K Corona: trad> tcond Evaporation Collapse n = 3.2  8.2 cm-3 T = 3  10  104 K Optical filament: n = 1.4  5 cm-3 T  1.14  106 K Core: trad< tcond n < 0.07 cm-3 Intercloud medium: T = 4  8  106 K trad> tcond

  12. cores: radiative cooling collapse coronae: thermal conduction evaporation Conclusions: • We resolved different phases in ISM clouds. • 3-D map of the observed clouds (FilD mass  1031g for a core particle density of 2 cm-3). • Discriminate model (no reflected shocks). • Evolution of the shocked clouds

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