2007/05/31 by Kevin Heng, Matthew van Adelsberg, Richard McCray +2 · 34 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Atomic physics #Balmer series #Dimensionless quantity #Emission spectrum #Gamma-ray bursts and supernovae #Ion #Ionization #Mechanics #Physics #Shock (circulatory) #Shock wave #Spectral line #astro-ph
paper · pdf · doi:10.1086/521298
published in The Astrophysical Journal 668(1), 275-284 (IOP Publishing) · 25 pages, 8 figures. Accepted by Astrophysical Journal
arxiv created 2007/06/28 · openalex publication_date 2007/10/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We examine the structure of the postshock region in supernova remnants (SNRs). The "shock transition zone" is set up by charge transfer and ionization events between atoms and ions and has a width ~(10 15 cm -2 ) n , where n 0 is the total preshock density (including both atoms and ions). For Balmer-dominated SNRs with shock velocity v s ≳ 1000 km s -1 , the Rankine-Hugoniot conditions for ion velocity and temperature are obeyed instantly, leaving the full width at half-maximum (FWHM) of the broad Hα line versus v s relation intact. However, the spatial variation in the postshock densities is relevant to the problem of Lyα resonant scattering in young, core-collapse SNRs. Both two- (preshock atoms and ions) and three-component (preshock atoms, broad neutrals, and ions) models are considered. We compute the spatial emissivities of the broad (ξ b ) and narrow (ξ n ) Hα lines; a calculation of these emissivities in SN 1006 is in general agreement with the computed ones of Raymond and coworkers. The (dimensionless) spatial shift, Θ shift , between the centroids of ξ b and ξ n is unique for a given shock velocity and f ion , the preshock ion fraction. Measurements of Θ shift can be used to constrain n 0 .