Thermal X-ray spectral tools. I. Parameterizing impulsive X-ray heating with a cumulative initial temperature (CIT) distribution
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States)
In collisional ionization equilibrium, the X-ray spectrum from a plasma depends on the differential emission measure (DEM), distributed over temperature. Due to the well-known ill conditioning problem, no precisely resolved DEM can be inverted directly from the spectrum, so often only a gross parameterization of the DEM is used to approximate the data, in hopes that the parameterization can provide useful model-independent constraints on the heating process. However, ill conditioning also introduces ambiguity into the various different parameterizations that could approximate the data, which may spoil the perceived advantages of model independence. Thus, this paper instead suggests a single parameterization for both the heating mechanism and the X-ray sources, based on a model of impulsive heating followed by radiative cooling. This approach is similar to a 'cooling flow' approach but allows injection at multiple initial temperatures and applies even when the steady state is a distribution of different shock strengths, as for a standing shock with a range of obliquities, or for embedded stochastic shocks that are only steady in a statistical sense. This produces an alternative parameterization for X-ray spectra that is especially streamlined for higher density plasmas with efficient radiative cooling and minimal thermal conduction and mixing. The method also provides some internal consistency checks on the validity of its assumptions. A heuristic general version is then applied over a wide range of astrophysical applications to schematically explore potential alternative models for these phenomena.
- OSTI ID:
- 22356631
- Journal Information:
- Astrophysical Journal, Vol. 788, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Flow of stellar wind past X-radiation source
SIGNATURES OF IMPULSIVE LOCALIZED HEATING IN THE TEMPERATURE DISTRIBUTION OF MULTI-STRANDED CORONAL LOOPS
Related Subjects
COSMOLOGY AND ASTRONOMY
APPROXIMATIONS
ASTROPHYSICS
COLLISIONAL PLASMA
COLLISIONS
DISTRIBUTION
EMISSION
EQUILIBRIUM
HEATING
PLASMA DENSITY
RADIATIVE COOLING
STEADY-STATE CONDITIONS
STOCHASTIC PROCESSES
TEMPERATURE DISTRIBUTION
THERMAL CONDUCTION
X RADIATION
X-RAY SOURCES
X-RAY SPECTRA