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Title: SUPERNOVA RESONANCE-SCATTERING LINE PROFILES IN THE ABSENCE OF A PHOTOSPHERE

Abstract

In supernova (SN) spectroscopy relatively little attention has been given to the properties of optically thick spectral lines in epochs following the photosphere's recession. Most treatments and analyses of post-photospheric optical spectra of SNe assume that forbidden-line emission comprises most if not all spectral features. However, evidence exists that suggests that some spectra exhibit line profiles formed via optically thick resonance-scattering even months or years after the SN explosion. To explore this possibility, we present a geometrical approach to SN spectrum formation based on the 'Elementary Supernova' model, wherein we investigate the characteristics of resonance-scattering in optically thick lines while replacing the photosphere with a transparent central core emitting non-blackbody continuum radiation, akin to the optical continuum provided by decaying {sup 56}Co formed during the explosion. We develop the mathematical framework necessary for solving the radiative transfer equation under these conditions and calculate spectra for both isolated and blended lines. Our comparisons with analogous results from the Elementary Supernova code SYNOW reveal several marked differences in line formation. Most notably, resonance lines in these conditions form P Cygni-like profiles, but the emission peaks and absorption troughs shift redward and blueward, respectively, from the line's rest wavelength by a significant amount,more » despite the spherically symmetric distribution of the line optical depth in the ejecta. These properties and others that we find in this work could lead to misidentification of lines or misattribution of properties of line-forming material at post-photospheric times in SN optical spectra.« less

Authors:
; ; ;  [1];  [2];  [3]
  1. Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Rm. 100, Norman, OK 73019 (United States)
  2. 6127 Wilder Lab, Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States)
  3. Computational Cosmology Center, Computational Research Division, Lawrence Berkeley National Laboratory, MS 50B-4206, 1 Cyclotron Road, CA 94720 (United States)
Publication Date:
OSTI Identifier:
22089796
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal, Supplement Series
Additional Journal Information:
Journal Volume: 203; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0067-0049
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; COBALT 56; COMPARATIVE EVALUATIONS; EMISSION SPECTROSCOPY; PHOTOSPHERE; RADIANT HEAT TRANSFER; RESCATTERING; RESONANCE; RESONANCE SCATTERING; S CODES; SUPERNOVAE; SYMMETRY; WAVELENGTHS

Citation Formats

Friesen, Brian, Baron, E., Branch, David, Chen Bin, Parrent, Jerod T., and Thomas, R. C. SUPERNOVA RESONANCE-SCATTERING LINE PROFILES IN THE ABSENCE OF A PHOTOSPHERE. United States: N. p., 2012. Web. doi:10.1088/0067-0049/203/1/12.
Friesen, Brian, Baron, E., Branch, David, Chen Bin, Parrent, Jerod T., & Thomas, R. C. SUPERNOVA RESONANCE-SCATTERING LINE PROFILES IN THE ABSENCE OF A PHOTOSPHERE. United States. doi:10.1088/0067-0049/203/1/12.
Friesen, Brian, Baron, E., Branch, David, Chen Bin, Parrent, Jerod T., and Thomas, R. C. Thu . "SUPERNOVA RESONANCE-SCATTERING LINE PROFILES IN THE ABSENCE OF A PHOTOSPHERE". United States. doi:10.1088/0067-0049/203/1/12.
@article{osti_22089796,
title = {SUPERNOVA RESONANCE-SCATTERING LINE PROFILES IN THE ABSENCE OF A PHOTOSPHERE},
author = {Friesen, Brian and Baron, E. and Branch, David and Chen Bin and Parrent, Jerod T. and Thomas, R. C.},
abstractNote = {In supernova (SN) spectroscopy relatively little attention has been given to the properties of optically thick spectral lines in epochs following the photosphere's recession. Most treatments and analyses of post-photospheric optical spectra of SNe assume that forbidden-line emission comprises most if not all spectral features. However, evidence exists that suggests that some spectra exhibit line profiles formed via optically thick resonance-scattering even months or years after the SN explosion. To explore this possibility, we present a geometrical approach to SN spectrum formation based on the 'Elementary Supernova' model, wherein we investigate the characteristics of resonance-scattering in optically thick lines while replacing the photosphere with a transparent central core emitting non-blackbody continuum radiation, akin to the optical continuum provided by decaying {sup 56}Co formed during the explosion. We develop the mathematical framework necessary for solving the radiative transfer equation under these conditions and calculate spectra for both isolated and blended lines. Our comparisons with analogous results from the Elementary Supernova code SYNOW reveal several marked differences in line formation. Most notably, resonance lines in these conditions form P Cygni-like profiles, but the emission peaks and absorption troughs shift redward and blueward, respectively, from the line's rest wavelength by a significant amount, despite the spherically symmetric distribution of the line optical depth in the ejecta. These properties and others that we find in this work could lead to misidentification of lines or misattribution of properties of line-forming material at post-photospheric times in SN optical spectra.},
doi = {10.1088/0067-0049/203/1/12},
journal = {Astrophysical Journal, Supplement Series},
issn = {0067-0049},
number = 1,
volume = 203,
place = {United States},
year = {2012},
month = {11}
}