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
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
Low spatial resolution
Low spectral resolution (E/DE < 2)
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.
The analysis of past X-ray observations left many open issues:
Impossibility of unambiguously describing the physics of the shock-cloud interaction.
ROSAT All Sky Survey (0.2-2.4 keV)
EPIC count rate images
~ 2.4 pc
Comparison between X-ray and optical emission in the FilD region
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.
Regions selected for spectral analysis
In each region the mean photon energy E has low fluctuations:
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
TII (106 K)
TI (106 K)
The values of the temperature of both components don’t show significant variations in the field of view.
nII2LII (1017 cm-5)
nI2LI (1017 cm-5)
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.
Evolution of the shocked clouds
n = 0.5 1.9 cm-3
T 3.0 106 K
n = 3.2 8.2 cm-3
T = 3 10 104 K
n = 1.4 5 cm-3
T 1.14 106 K
n < 0.07 cm-3
T = 4 8 106 K
cores: radiative cooling collapse
coronae: thermal conduction evaporation
(FilD mass 1031g for a core particle density of 2 cm-3).