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Title: EVOLUTION OF HIGH-ENERGY PARTICLE DISTRIBUTION IN MATURE SHELL-TYPE SUPERNOVA REMNANTS

Abstract

Multi-wavelength observations of mature supernova remnants (SNRs), especially with recent advances in γ -ray astronomy, make it possible to constrain energy distribution of energetic particles within these remnants. In consideration of the SNR origin of Galactic cosmic rays and physics related to particle acceleration and radiative processes, we use a simple one-zone model to fit the nonthermal emission spectra of three shell-type SNRs located within 2° on the sky: RX J1713.7−3946, CTB 37B, and CTB 37A. Although radio images of these three sources all show a shell (or half-shell) structure, their radio, X-ray, and γ -ray spectra are quite different, offering an ideal case to explore evolution of energetic particle distribution in SNRs. Our spectral fitting shows that (1) the particle distribution becomes harder with aging of these SNRs, implying a continuous acceleration process, and the particle distributions of CTB 37A and CTB 37B in the GeV range are harder than the hardest distribution that can be produced at a shock via the linear diffusive shock particle acceleration process, so spatial transport may play a role; (2) the energy loss timescale of electrons at the high-energy cutoff due to synchrotron radiation appears to be always a bit (within a factormore » of a few) shorter than the age of the corresponding remnant, which also requires continuous particle acceleration; (3) double power-law distributions are needed to fit the spectra of CTB 37B and CTB 37A, which may be attributed to shock interaction with molecular clouds.« less

Authors:
; ; ;  [1];  [2];  [3]
  1. Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)
  2. University of Arizona, Tucson, Arizona, 85721 (United States)
  3. Key Laboratory of Astroparticle Physics of Yunnan Province, Kunming, 650091 (China)
Publication Date:
OSTI Identifier:
22661362
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 834; 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; AGING; CLOUDS; COSMIC RADIATION; EMISSION SPECTRA; ENERGY LOSSES; ENERGY SPECTRA; GAMMA ASTRONOMY; GAMMA RADIATION; GAMMA SPECTRA; GEV RANGE; IMAGES; MILKY WAY; SUPERNOVA REMNANTS; SYNCHROTRON RADIATION; WAVELENGTHS; X RADIATION

Citation Formats

Zeng, Houdun, Xin, Yuliang, Liu, Siming, Zhang, Shuinai, Jokipii, J. R., and Zhang, Li, E-mail: zhd@pmo.ac.cn, E-mail: liusm@pmo.ac.cn. EVOLUTION OF HIGH-ENERGY PARTICLE DISTRIBUTION IN MATURE SHELL-TYPE SUPERNOVA REMNANTS. United States: N. p., 2017. Web. doi:10.3847/1538-4357/834/2/153.
Zeng, Houdun, Xin, Yuliang, Liu, Siming, Zhang, Shuinai, Jokipii, J. R., & Zhang, Li, E-mail: zhd@pmo.ac.cn, E-mail: liusm@pmo.ac.cn. EVOLUTION OF HIGH-ENERGY PARTICLE DISTRIBUTION IN MATURE SHELL-TYPE SUPERNOVA REMNANTS. United States. doi:10.3847/1538-4357/834/2/153.
Zeng, Houdun, Xin, Yuliang, Liu, Siming, Zhang, Shuinai, Jokipii, J. R., and Zhang, Li, E-mail: zhd@pmo.ac.cn, E-mail: liusm@pmo.ac.cn. Tue . "EVOLUTION OF HIGH-ENERGY PARTICLE DISTRIBUTION IN MATURE SHELL-TYPE SUPERNOVA REMNANTS". United States. doi:10.3847/1538-4357/834/2/153.
@article{osti_22661362,
title = {EVOLUTION OF HIGH-ENERGY PARTICLE DISTRIBUTION IN MATURE SHELL-TYPE SUPERNOVA REMNANTS},
author = {Zeng, Houdun and Xin, Yuliang and Liu, Siming and Zhang, Shuinai and Jokipii, J. R. and Zhang, Li, E-mail: zhd@pmo.ac.cn, E-mail: liusm@pmo.ac.cn},
abstractNote = {Multi-wavelength observations of mature supernova remnants (SNRs), especially with recent advances in γ -ray astronomy, make it possible to constrain energy distribution of energetic particles within these remnants. In consideration of the SNR origin of Galactic cosmic rays and physics related to particle acceleration and radiative processes, we use a simple one-zone model to fit the nonthermal emission spectra of three shell-type SNRs located within 2° on the sky: RX J1713.7−3946, CTB 37B, and CTB 37A. Although radio images of these three sources all show a shell (or half-shell) structure, their radio, X-ray, and γ -ray spectra are quite different, offering an ideal case to explore evolution of energetic particle distribution in SNRs. Our spectral fitting shows that (1) the particle distribution becomes harder with aging of these SNRs, implying a continuous acceleration process, and the particle distributions of CTB 37A and CTB 37B in the GeV range are harder than the hardest distribution that can be produced at a shock via the linear diffusive shock particle acceleration process, so spatial transport may play a role; (2) the energy loss timescale of electrons at the high-energy cutoff due to synchrotron radiation appears to be always a bit (within a factor of a few) shorter than the age of the corresponding remnant, which also requires continuous particle acceleration; (3) double power-law distributions are needed to fit the spectra of CTB 37B and CTB 37A, which may be attributed to shock interaction with molecular clouds.},
doi = {10.3847/1538-4357/834/2/153},
journal = {Astrophysical Journal},
number = 2,
volume = 834,
place = {United States},
year = {Tue Jan 10 00:00:00 EST 2017},
month = {Tue Jan 10 00:00:00 EST 2017}
}
  • Results for the Galactic distribution of shell-type SNRs are obtained, using empirically derived correction factors to account for selection effects. The spatial distribution has a peak 4-6 kpc from the Galactic center, and is shown to resemble that obtained by Johnson and MacLeod (1963) for spiral galaxy SN. Using the Cox (1979) model, an average SNR age of 6800 yr is found with about 50 percent uncertainty. Constraints are placed on the SNR birthrate which are consistent with the SN rate. 24 refs.
  • Nonthermal radiative properties of three TeV shell-type supernova remnants (SNRs) RX J1713.7-3946, RX J0852.0-4622, and RCW 86, argued to be expanding into low-density hot bubbles created by the wind of the massive progenitor stars, are investigated based on a semi-analytical solution to diffusive acceleration at nonlinear shocks. In the model, a free-escape boundary upstream of the shock is used to mimic the escape of cosmic rays from the SNR, with the dynamic reaction of the self-generated magnetic field via resonant streaming instability on the shock taken into account. Origins of the {gamma}-rays from the three remnants are studied with appropriatemore » parameters, and consistent results with the multiband observed fluxes are obtained within the nonlinear diffusive shock acceleration regime. The order of the resulting downstream magnetic field strength for the three SNRs is between 60 and 100 {mu}G, and the observed TeV {gamma}-rays are mainly produced via the decay of neutral {pi} mesons produced from the hadronic collisions.« less
  • Supernova remnants (SNRs) retain crucial information about both their parent explosion and circumstellar material left behind by their progenitor. However, the complexity of the interaction between supernova ejecta and ambient medium often blurs this information, and it is not uncommon for the basic progenitor type (Ia or core-collapse) of well-studied remnants to remain uncertain. Here we present a powerful new observational diagnostic to discriminate between progenitor types and constrain the ambient medium density of SNRs using solely Fe K-shell X-ray emission. We analyze all extant Suzaku observations of SNRs and detect Fe Kα emission from 23 young or middle-aged remnants,more » including five first detections (IC 443, G292.0+1.8, G337.2-0.7, N49, and N63A). The Fe Kα centroids clearly separate progenitor types, with the Fe-rich ejecta in Type Ia remnants being significantly less ionized than in core-collapse SNRs. Within each progenitor group, the Fe Kα luminosity and centroid are well correlated, with more luminous objects having more highly ionized Fe. Our results indicate that there is a strong connection between explosion type and ambient medium density, and suggest that Type Ia supernova progenitors do not substantially modify their surroundings at radii of up to several parsecs. We also detect a K-shell radiative recombination continuum of Fe in W49B and IC 443, implying a strong circumstellar interaction in the early evolutionary phases of these core-collapse remnants.« less