Chandra Observations and Models of the Mixed-Morphology Supernova Remnant W44: Global Trends

Abstract

As with other mixed morphology remnants, W44's projected center is bright in thermal X-rays. It has an obvious radio shell, but no discernable X-ray shell. X-ray bright knots dot W44's image. The Chandra data show that the remnant's hot, bright projected center is metal-rich and that the bright knots are regions of comparatively elevated elemental abundances. The neon abundance is elevated, suggesting that the center is rich in ejecta. Furthermore, some of the emitting iron atoms appear to be underionized with respect to the other ions, providing the first X-ray evidence for dust destruction in a supernova remnant. We use the Chandra data to test the following explanations for W44's X-ray bright center: 1.) entropy mixing from thermal conduction or bulk mixing, 2.) cloud evaporation, and 3.) a metallicity gradient, possibly due to dust destruction and ejecta enrichment. In these tests, we assume that the remnant has evolved beyond the adiabatic evolutionary stage, which explains the X-ray dimness of the shell. The entropy mixed model spectrum was found to be a good match to the Chandra spectrum. The bright knots have similar levels of ionization as the surrounding regions, challenging the evaporating clouds model. While both of these models are known to predict centrally bright X-ray morphologies, their predictions fall short of the observed brightness gradient. The resulting brightness gap can be largely filled in by emission from the extra metals in and near the remnant's projected center. The preponderance of evidence suggests that W44's remarkable morphology can be attributed to dust destruction and ejecta enrichment within an entropy mixed, adiabatic phase supernova remnant.

arXiv commentAccepted for publication in the August 20, 2004 issue of ApJ. 22 pages (in well spaced layout), references, captions, and figures

References in corpus (17)

• Ionization balance for optically thin plasmas: rate coefficients for all atoms and ions of the elements H to Ni
• Supernova Remnants in Molecular Clouds
• Polarization Observations of 1720 MHz OH Masers toward the Three Supernova Remnants W28, W44, and IC443
• Mitigating Charge Transfer Inefficiency in the Chandra X-ray Observatory's ACIS Instrument
• Modeling W44 as a Supernova Remnant in a Density Gradient, with a Partially Formed Dense Shell and Thermal Conduction in the Hot Interior
• ASCA Observations of the Supernova Remnant IC 443: Thermal Structure and Detection of Overionized Plasma
• The Pulsar Wind Nebula Around PSR B1853+01 in the Supernova Remnant W44
• Supernova Remnants in the Magellanic Clouds III: An X-ray Atlas of LMC Supernova Remnants
• $10^{51}$ Ergs: The Evolution of Shell Supernova Remnants
• The X-ray Structure and Spectrum of the Pulsar Wind Nebula Surrounding PSR B1853+01 in W44
• Interpretation of the Center-Filled Emission from the Supernova Remnant W44
• ASCA Observations of the Thermal Composite Supernova Remnant 3C 391
• Thermal X-ray composites as an effect of projection
• The Radial Structure of the Cygnus Loop Supernova Remnant --- Possible evidence of a cavity explosion ---
• Discovery of an X-ray Synchrotron Nebula Associated with the Radio Pulsar PSR B1853+01 in the Supernova Remnant W44
• A Broadband X-Ray Study of the Supernova Remnant 3C 397
• Centrally Peaked X-Ray Supernova Remnants in the Small Magellanic Cloud Studied with ASCA and ROSAT

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