Forbidden Line Emission from Type Ia Supernova Remnants Containing Balmer-Dominated Shells

Abstract

Balmer-dominated shells in supernova remnants (SNRs) are produced by collisionless shocks advancing into a partially neutral medium, and are most frequently associated with Type Ia supernovae. We have analyzed Hubble Space Telescope (HST) images and VLT/MUSE or AAT/WiFeS observations of five Type Ia SNRs containing Balmer-dominated shells in the LMC: 0509-67.5, 0519-69.0, N103B, DEM L71, and 0548-70.4. Contrary to expectations, we find bright forbidden line emission from small dense knots embedded in four of these SNRs. The electron densities in some knots are higher than 10${}^4$ cm${}^{-3}$. The size and density of these knots are not characteristic for interstellar medium (ISM) -- they most likely originate from a circumstellar medium (CSM) ejected by the SN progenitor. Physical property variations of dense knots in the SNRs appear to reflect an evolutionary effect. The recombination timescales for high densities are short, and HST images of N103B taken 3.5 yr apart already show brightness changes in some knots. VLT/MUSE observations detect [Fe XIV] line emission from reverse shocks into SN ejecta as well as forward shocks into the dense knots. Faint [O III] line emission is also detected from the Balmer shell in 0519-69.0, N103B, and DEM L71. We exclude the postshock origin because the [O III] line is narrow. For the preshock origin, we considered three possibilities: photoionization precursor, cosmic ray precursor, and neutral precursor. We conclude that the [O III] emission arises from oxygen that has been photoionized by [He II] $\lambda$304 photons and is then collisionally excited in a shock precursor heated mainly by cosmic rays.

arXiv comment20 pages, 2 tables, 14 figures, accepted for publication in The Astrophysical Journal (ApJ)

References in corpus (29)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• The NumPy array: a structure for efficient numerical computation
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• CHIANTI - An atomic database for Emission Lines. Version 8
• Balmer-Dominated Spectra of Nonradiative Shocks in the Cygnus Loop, RCW 86 and Tycho Supernova Remnants
• Echoes from Ancient Supernovae in the Large Magellanic Cloud
• Electron-Ion Temperature Equilibration in Collisionless Shocks: the Supernova Remnant-Solar Wind Connection
• Balmer-Dominated Shocks: A Concise Review
• High Resolution Spectroscopy of Balmer-Dominated Shocks in the RCW 86, Kepler and SN 1006 Supernova Remnants
• Resolved shock structure of the Balmer-dominated filaments in Tycho's supernova remnant: Cosmic-ray precursor?
• Abundances and density structure of the inner circumstellar ring around SN 1987A
• The Destruction of the Circumstellar Ring of SN 1987A
• The Physics of Supernova Remnant Blast Waves. I. Kinematics of DEM L71 in the Large Magellanic Cloud
• Collisionless shock in a partially ionized medium. II. Balmer emission
• Optical tomography of chemical elements synthesized in Type Ia supernovae
• Calibrating Interstellar Abundances using SNR Radiative Shocks
• Collisionless shocks in a partially ionized medium: III. Efficient cosmic ray acceleration
• Spitzer Observations of the Type Ia Supernova Remnant N103B: Kepler's Older Cousin?
• ALMA CO Observations of Gamma-Ray Supernova Remnant N132D in the Large Magellanic Cloud: Possible Evidence for Shocked Molecular Clouds Illuminated by Cosmic-Ray Protons
• Shocked Interstellar clouds and dust grain destruction in the LMC Supernova Remnant N132D
• Search for Surviving Companions of Progenitors of Young LMC Type Ia Supernova Remnants
• Physical Structures of the Type Ia Supernova Remnant N103B
• Integral Field Spectroscopy of Balmer-Dominated Shocks in the Magellanic Cloud Supernova Remnant N103B
• ALMA CO Observations of Supernova Remnant N63A in the Large Magellanic Cloud: Discovery of Dense Molecular Clouds Embedded within Shock-Ionized and Photoionized Nebulae
• Spatially-Resolved Spectroscopy of a Balmer-Dominated Shock in the Cygnus Loop: An Extremely Thin Cosmic-Ray Precursor?
• Constraints on Cosmic-ray Acceleration Efficiency in Balmer Shocks of Two Young Type Ia Supernova Remnants in the Large Magellanic Cloud
• Balmer filaments in Tycho's supernova remnant: an interplay between cosmic-ray and broad-neutral precursors
• Imagery and UV Spectroscopy of the LMC Supernova Remnant N103B Using HST

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