Diagnostics of the origin of X- ray emission in Cygnus Loop Xin Zhou, INAF – Osservatorio Astronomico di Palermo, Italy & Nanjing University, ChinaCollaborators: Fabrizio Bocchino, INAF – Osservatorio Astronomico di Palermo, Italy Marco Miceli, Università di Palermo, Italy & INAF – Osservatorio Astronomico di Palermo, Italy Salvatore Orlando, INAF – Osservatorio Astronomico di Palermo, Italy Yang Chen, Nanjing University, China

ROSAT HRI Numerical models Diagnostic tools Observation The role of TC

Numerical Models: Orlando et al, 2005, A&A, 444, 505; Orlando et al. 2010, A&A, 514, 29 Case table n ISM =0.1 cm -3 T ISM =10 4 K

Results of models — fluid structure: Orlando et al Stronger transmitted shock; Weaker reflected shock; Depress the HY instabilities; Reducing the mixing of the cloud; Evaporating the cloud material. Without TC With TC

Results of models — X-ray emission: Orlando et al. 2006, A&A, 457, 545 Two seperate high-emission regions in pure HY model; HY instabilities are not clearly visible from X-ray emission.

What affects the efficiency of TC: Orlando et al. 2008, ApJ, 678, 274; Orlando et al Density contrast (between the cloud and surrounding medium); Velocity of shock; Magnetic field.

Analytic tools to know when TC is efficient: Orlando et al. 2010; Miceli et al. 2006, A&A, 458, 213 When TC is efficient: T low [DR]/T low [knot] > 1; em low [DR]/em low [knot] < 0.5. the MPE vs CR plot is flatter.

ROSAT HRI XA region, observed by XMM the Cygnus Loop: Zhou et al Hard band emission gives the information of the distribution of ejecta; The shock front is curved; Central low MPE region indicates a “dense finger”; The long strip indicates a large extension of the central “dense finger”; Clumpy features in soft band map and the diffuse emission behind them in the medium band map;

Zhou et al Spectral analysis: Abundance of shocked ISM is low; Hot component in regions 4 and 9 mainly originate from ejecta; T ejecta >T ISM.

Fig.3 Zhou et al The slope is flatter then the model without TC (~-0.45); TC is less efficient in region 7&8; The ascending trend in region 3&4 may caused by the presence of ejecta. TC is predominant in all of the shock-cloud interaction regions.

Summary: TC is important to understand the evolution of shock-cloud interaction; In the XA region: The surrounding ISM is dense and clumpy; TC is prominent in all the shock-cloud interaction regions; In addition: The abundances of the surrounding ISM are found to be lower than the solar value; A long bent “finger” protruding from the cavity wall is present in this region, which was not known before.

The End. Thanks for your attention!!