A Comparison of X-ray and Radio Emission from the Supernova Remnant Cassiopeia A

Abstract

We compare the radio and soft X-ray brightness as a function of position within the young supernova remnant Cassiopeia A. A moderately strong correlation (r = 0.7) was found between the X-ray emission (corrected for interstellar absorption) and radio emission, showing that the thermal and relativistic plasmas occupy the same volumes and are regulated by common underlying parameters. The logarithmic slope of the relationship, ln(Sx-ray) = 1.2 x Sradio + ln(k) implies that the variations in brightness are primarily due to path length differences. The X-ray and radio emissivities are both high in the same general locations, but their more detailed relationship is poorly constrained and probably shows significant scatter. The strongest radio and X-ray absorption is found at the western boundary of Cas A. Based on the properties of Cas A and the absorbing molecular cloud, we argue that they are physically interacting. We also compare ASCA derived column densities with 21 cm H I and 18 cm OH optical depths in the direction of Cas A, in order to provide an independent estimate of ISM properties. We derive an average value for the H I spin temperature of about 40 K and measure the ratio of OH to molecular hydrogen to be nominally larger than previous estimates. Keywords: Cas A, Cassiopeia A, interstellar medium, molecular clouds, radio astronomy, supernova remnants, X-ray astronomy

arXiv commentTo appear in Vol. 446 of The Astrophysical Journal on Aug. 1, 1996; 10 pages with 5 embedded figures; replaced because of updated references

Cited by in corpus (40)

• Nucleosynthesis and Mixing in Cassiopeia A
• Contour binning: a new technique for spatially-resolved X-ray spectroscopy applied to Cassiopeia A
• X-ray spectral imaging and Doppler mapping of Cassiopeia A
• The Compact Central Object in Cas A: A Neutron Star with Hot Polar Caps or a Black Hole?
• Mapping the X-ray Emitting Ejecta in Cassiopeia A with Chandra
• Cassiopeia A and its Clumpy Presupernova Wind
• A Detailed Kinematic Map of Cassiopeia A's Optical Main Shell and Outer High-Velocity Ejecta
• The Central X-Ray Point Source in Cassiopeia A
• Newly Synthesized Elements and Pristine Dust in the Cassiopeia A Supernova Remnant
• The Bubble-like Interior of the Core-Collapse Supernova Remnant Cassiopeia A
• $10^{51}$ Ergs: The Evolution of Shell Supernova Remnants
• Hubble Space Telescope WFPC-2 Imaging of Cassiopeia A
• A Systematic Survey for Broadened CO Emission Toward Galactic Supernova Remnants
• AKARI and BLAST Observations of the Cassiopeia A Supernova Remnant and Surrounding Interstellar Medium
• The X-ray nebula of the filled center supernova remnant 3C58 and its interaction with the environment
• Cosmic ray diffusion near the Bohm limit in the Cassiopeia A supernova remnant
• X-ray Measurements of the Particle Acceleration Properties at Inward Shocks in Cassiopeia A
• An HST Survey of the Highest-Velocity Ejecta in Cassiopeia A
• Evidence for past interaction with an asymmetric circumstellar shell in the young SNR Cassiopeia A
• Near-Infrared and Optical Limits for the Central X-ray Point Source in the Cassiopeia A Supernova Remnant
• The X-ray Expansion of the Supernova Remnant Cassiopeia A
• The Reddening Towards Cassiopeia A's Supernova: Constraining the 56Ni Yield
• Kinematics of X-ray Emitting Components in Cassiopeia A
• A Decline in the Nonthermal X-ray Emission from Cassiopeia A
• The X-ray Source at the Center of the Cassiopeia A Supernova Remnant
• The Shape of Cas A
• The Circumstellar Medium of Cassiopeia A Inferred from the Outer Ejecta Knot Properties
• Discovery of Radio/X-ray/Optical Resolved Supernova Remnants in the Center of the Andromeda Galaxy
• Interaction between Cassiopeia A and Nearby Molecular Clouds
• Molecular gas toward supernova remnant Cassiopeia A
• A Deep Near-Infrared [Fe II]+[Si I] Emission Line Image of the Supernova Remnant Cassiopeia A
• Near-infrared Extinction due to Cool Supernova Dust in Cassiopeia A
• X-ray Absorption in Young Core-Collapse Supernova Remnants
• High spatial resolution X-ray spectroscopy of SNR Cassiopeia A with {\sl Chandra}
• Probing Shock Properties with Non-thermal X-ray Filaments in Cas A
• Evidence for Proportionate Partition Between the Magnetic Field and Hot Gas in Turbulent Cassiopeia A
• A Multi-Frequency Study of the Milky Way-like Spiral Galaxy NGC 6744
• The Korean 1592--1593 Record of a Guest Star: An `impostor' of the Cassiopeia A Supernova?
• Spatially resolved spectroscopy of Cassiopeia A with MECS on board BeppoSAX
• The forward and reverse shock dynamics of Cassiopeia A