NOAO >   Observing Info >   Approved Programs >   2013A-0397

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Proposal Information for 2013A-0397


PI: P. Frank Winkler, Middlebury College, winkler@middlebury.edu
Address: Physics Department, Bicentennial Way, Middlebury, VT 05753, USA

CoI: Knox S. Long, Space Telescope Science Institute
CoI: William P. Blair, The Johns Hopkins University

Title: SNR Shocks and Cosmic Rays: a Critical Test in RCW86

Abstract: We propose to measure the efficiency of cosmic ray acceleration in fast supernova remnant shocks in the NE region of RCW 86-probable remnant of SN 185 and the ideal venue for such a measurement. We will find the shock velocity by measuring the proper motions for crisp Balmer filaments that delineate the shock front (the distance is well known), and we will obtain the the post-shock proton temperature spectroscopically from the widths of the broad Balmer lines emanating from these filaments. We plan to use GMOS on Gemini South for both measurements: direct imaging in \ha and a matched continuum to use as second-epoch images for measuring the proper motions through comparison with images from the Blanco + Mosaic II in 2010; and deep spectra at two positions cutting across the filaments, to obtain the Balmer line profiles and hence the post-shock temperature. Our experiment will resolve potential problems with the results of Helder \etal (2009), who from optical spectra measured a Balmer linewidth of 1100 km/s (FWHM). But in a proper motion measurement based on X-ray images, they found a surprisingly high shock velocity of 6000 km/s, far faster than elsewhere in RCW 86. If correct, their measurements suggest that a large fraction of shock energy goes into cosmic ray acceleration. But the proper-motion measurement has high uncertainty, and does \it not coincide with the slit position for their optical spectrum.


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