Hot interstellar tunnels. I. Simulation of interacting supernova remnants

Journal Article · Sat Jan 15 04:00:00 EST 1977 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/154946· OSTI ID:7115973

Smith, B W

Reexamining a suggestion of Cox and Smith, we find that intersecting supernova remnants can indeed generate and maintain hot interstellar regions with napproximately-less-than10/sup -2/ cm/sup -3/ and Tapprox.10/sup 6/ K. These regions are likely to occupy at least 30% of the volume of a spiral arm near the midplane of the gaseous disk if the local supernova rate there is greater than 1.5 x 10/sup -7/ Myr/sup -1/ pc/sup -3/. Their presence in the interstellar medium is supported by observations of the soft X-ray background. The theory required to build a numerical simulation of interacting supernova remnants is developed. The hot cavities within a population of remnants will become connected for a variety of assumed conditions in the outer shells of old remnants. Extensive hot cavity regions or tunnels are built and enlarged by supernovae occurring in relatively dense gas which produce connections, but tunnels are kept hot primarily by supernovae occurring within the tunnels. The latter supernovae initiate fast shock waves which apparently reheat tunnels faster than they are destroyed by thermal conduction in a galactic magnetic field or by radiative cooling. However, the dispersal of these rejuvenating shocks over a wide volume is inhibited by motions of cooler interstellar gas in the interval between shocks. These motions disrupt the contiguity of the component cavities of a tunnel and may cause its death.The Monte Carlo simulations indicate that a quasi-equilibrium is reached within 10/sup 7/ years of the first supernova in a spiral arm. This equilibrium is characterized by a constant average filling fraction for cavities in the interstellar volume. Aspects of the equilibrium are discussed for a range of supernova rates. Two predictions of Cox and Smith are not confirmed within this range: critical growth of hot regions to encompass the entire medium, and the efficient quenching of a remnant's expansion by interaction with other cavities.

• Research Organization: Space Physics Laboratory, University of Wisconsin-Madison
• OSTI ID: 7115973
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 211:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC RADIATION
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
ENERGY TRANSFER
FLUID MECHANICS
HEAT TRANSFER
HYDRODYNAMICS
INSTABILITY
INTERSTELLAR SPACE
IONIZING RADIATIONS
MECHANICS
MONTE CARLO METHOD
RADIATIONS
RAYLEIGH-TAYLOR INSTABILITY
SHOCK WAVES
SIMULATION
SPACE
STAR EVOLUTION
SUPERNOVA REMNANTS
THERMAL CONDUCTION
X RADIATION