Context :

Aims : Wewanttoprobethephysicsoffastcollision-lessshocksinsupernovaremnants.Weareinterestedinthenon-equilibrationoftemperaturesandparticleacceleration.Specifically , weaimtomeasuretheoxygentemperaturewithregardstotheelectrontemperature.Inaddition , wesearchforsynchrotronemissioninthenorthwesternthermalrim .

Methods : ThisstudyispartofadedicateddeepobservationalprojectofSN1006usingXMM-Newton , whichprovidesuswithcurrentlythebestresolutionspectraofthebrightnorthwesternoxygenknot.Weaimtousethereflectiongratingspectrometertomeasurethethermalbroadeningofthe { O \textsc { vii } } linetripletbyconvolvingtheemissionprofileoftheremnantwiththeresponsematrix .

Results : Thelinebroadeningwasmeasuredtobe \sigma _ { e } = 2.4 \pm 0.3 eV , correspondingtoanoxygentemperatureof 275 ^ { +72 } _ { -63 } keV.FromtheEPICspectraweobtainanelectrontemperatureof 1.35 \pm 0.10 keV.Thedifferenceintemperaturebetweenthespeciesprovidesfurtherevidenceofnon-equilibrationoftemperaturesinashock.Inaddition , wefindevidenceforabowshockthatemitsX-raysynchrotronradiation , whichisatoddswiththegeneralideathatduetothemagneticfieldorientationonlyintheNEandSWregionX-raysynchrotronradiationshouldbeemitted.WefindanunusualH \alpha andX-raysynchrotrongeometry , inthattheH \alpha emissionpeaksdownstreamofthesynchrotronemission.ThismaybeanindicationforapeculiarH \alpha shock , inwhichthedensityislowerandneutralfractionarehigherthaninothersupernovaremnants , resultinginapeakinH \alpha emissionfurtherdownstreamoftheshock .

Conclusions :