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Title: TIME-DEPENDENT DIFFUSIVE SHOCK ACCELERATION IN SLOW SUPERNOVA REMNANT SHOCKS

Abstract

Recent gamma-ray observations show that middle-aged supernova remnants (SNRs) interacting with molecular clouds can be sources of both GeV and TeV emission. Models involving reacceleration of preexisting cosmic rays (CRs) in the ambient medium and direct interaction between SNR and molecular clouds have been proposed to explain the observed gamma-ray emission. For the reacceleration process, standard diffusive shock acceleration (DSA) theory in the test particle limit produces a steady-state particle spectrum that is too flat compared to observations, which suggests that the high-energy part of the observed spectrum has not yet reached a steady state. We derive a time-dependent DSA solution in the test particle limit for situations involving reacceleration of preexisting CRs in the preshock medium. Simple estimates with our time-dependent DSA solution plus a molecular cloud interaction model can reproduce the overall shape of the spectra of IC 443 and W44 from GeV to TeV energies through pure π{sup 0}-decay emission. We allow for a power-law momentum dependence of the diffusion coefficient, finding that a power-law index of 0.5 is favored.

Authors:
;  [1]
  1. Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)
Publication Date:
OSTI Identifier:
22522098
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 800; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; CLOUDS; COMPARATIVE EVALUATIONS; COSMIC RADIATION; DIFFUSION; EMISSION SPECTRA; GAMMA RADIATION; GEV RANGE; PHOTON EMISSION; SUPERNOVA REMNANTS; TEV RANGE; TIME DEPENDENCE

Citation Formats

Tang, Xiaping, and Chevalier, Roger A., E-mail: xt5ur@virginia.edu, E-mail: rac5x@virginia.edu. TIME-DEPENDENT DIFFUSIVE SHOCK ACCELERATION IN SLOW SUPERNOVA REMNANT SHOCKS. United States: N. p., 2015. Web. doi:10.1088/0004-637X/800/2/103.
Tang, Xiaping, & Chevalier, Roger A., E-mail: xt5ur@virginia.edu, E-mail: rac5x@virginia.edu. TIME-DEPENDENT DIFFUSIVE SHOCK ACCELERATION IN SLOW SUPERNOVA REMNANT SHOCKS. United States. doi:10.1088/0004-637X/800/2/103.
Tang, Xiaping, and Chevalier, Roger A., E-mail: xt5ur@virginia.edu, E-mail: rac5x@virginia.edu. Fri . "TIME-DEPENDENT DIFFUSIVE SHOCK ACCELERATION IN SLOW SUPERNOVA REMNANT SHOCKS". United States. doi:10.1088/0004-637X/800/2/103.
@article{osti_22522098,
title = {TIME-DEPENDENT DIFFUSIVE SHOCK ACCELERATION IN SLOW SUPERNOVA REMNANT SHOCKS},
author = {Tang, Xiaping and Chevalier, Roger A., E-mail: xt5ur@virginia.edu, E-mail: rac5x@virginia.edu},
abstractNote = {Recent gamma-ray observations show that middle-aged supernova remnants (SNRs) interacting with molecular clouds can be sources of both GeV and TeV emission. Models involving reacceleration of preexisting cosmic rays (CRs) in the ambient medium and direct interaction between SNR and molecular clouds have been proposed to explain the observed gamma-ray emission. For the reacceleration process, standard diffusive shock acceleration (DSA) theory in the test particle limit produces a steady-state particle spectrum that is too flat compared to observations, which suggests that the high-energy part of the observed spectrum has not yet reached a steady state. We derive a time-dependent DSA solution in the test particle limit for situations involving reacceleration of preexisting CRs in the preshock medium. Simple estimates with our time-dependent DSA solution plus a molecular cloud interaction model can reproduce the overall shape of the spectra of IC 443 and W44 from GeV to TeV energies through pure π{sup 0}-decay emission. We allow for a power-law momentum dependence of the diffusion coefficient, finding that a power-law index of 0.5 is favored.},
doi = {10.1088/0004-637X/800/2/103},
journal = {Astrophysical Journal},
number = 2,
volume = 800,
place = {United States},
year = {Fri Feb 20 00:00:00 EST 2015},
month = {Fri Feb 20 00:00:00 EST 2015}
}