Statistics – Computation
Scientific paper
Dec 2004
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004aas...205.8404s&link_type=abstract
American Astronomical Society Meeting 205, #84.04; Bulletin of the American Astronomical Society, Vol. 36, p.1481
Statistics
Computation
Scientific paper
X-ray observations of thermally dominated young supernova remnants such as Cassiopeia A, Kepler, and Tycho show complex morphology. The color separations visible in any energy-colored counts image of one of these remnants suggest the different physics occurring in different regions, for example, thermally emitting ejecta lobes and nonthermally radiating outer shocks. However, there is considerable physics which is still hidden: temperature variation, ionisation states, true separation of line and continuum emission, effects of interstellar (and perhaps circumstellar) absorption, and the velocity of the ejecta. Using the spectroscopic capability of the Chandra Advanced CCD Imaging Spectrometer, we can literally map the spectral features of remnants. We will briefly explain our techniques using the Interactive Spectral Interpretation System (ISIS) and the Chandra Interactive Analysis of Observations software for reducing and analyzing the data to produce high resolution (1'' to 5'') maps of the spectral parameters of Cas A, Kepler, and Tycho. Our process is a two-phase approach, and we will compare and contrast some of the ``first'' and ``second'' generation analysis products for these remnants. The first analysis phase consists of an initial mapping using computationally simple models to represent the major line and continuum features of the remnant. In the second phase, we use the first set of maps to identify and locate regions of interest to fit with specialized models. For example, we have discovered that anomalously high fit temperatures to the bremsstrahlung model in the first map is a powerful indicator of regions which are dominated by synchrotron emission. Fitting these identified regions with the more appropriate synchrotron model allows us to measure the rates of particle acceleration in the shock fronts (see Allen et al., this conference) and show that the rates approach the Bohm limit. We will briefly present some of these synchrotron emission results, as well as results for the velocity and structure of the thermal emission in these young remnants. This work is made possible in part by the NASA LTSA grant NAG5-9237.
Allen Glenn E.
Davis Jesse E.
Houck John C.
Stage Michael D.
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