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D. N. Burrows, S. Park (Penn State University), S. Zhekov, E. Michael, R. McCray (U. Colorado), G. P. Garmire (Penn State University)
We report on the results of our monitoring program of the remnant of SN 1987A with the Advanced CCD Imaging Spectrometer (ACIS) on the Chandra X-ray Observatory. Two new observations have been performed in AO2, bringing the total to four monitoring observations over the past two years. A fifth observation is scheduled for November 2001 and may be included in the poster as well.
Over the past two years, the data processing techniques available to us at Penn State have expanded, and now include special techniques for correction of imperfect Charge Transfer Efficiency and for use of charge spreading to provide angular resolution at better than the pixel size of the CCD detector. We have processed all of our observations using sub-pixel resolution to obtain the highest possible angular resolution, and using our CTI correction software to provide more reliable spectral analysis and flux estimations.
We report the results of the data analysis from all of the four Chandra observations of SN 1987A. The high angular resolution images indicate the associations of soft X-ray bright knots with the optical hot spots as observed with HST, while hard X-ray features are better correlated with radio images. This can be understood in terms of a model in which fast shocks propagating through the circumstellar HII region produce the hard X-ray and radio emission, while the soft X-ray and UV emission arise in slower shocks propagating into high-density knots in the circumstellar inner ring. The X-ray flux variation implies an increase of 60% over the 18-month period of these observations, with the X-ray flux currently increasing linearly. Finally, we present evidence for direct detection of the expansion rate of the X-ray remnant.