A Rapid Ionization Change in the Nebular-Phase Spectra of the Type Ia SN 2011fe

Abstract

We present three new spectra of the nearby Type Ia supernova (SN Ia) 2011fe covering $\approx 480-850$days after maximum light and show that the ejecta undergoes a rapid ionization shift at $\sim 500$days after explosion. The prominent [FeIII] emission lines at $\approx 4600$Å are replaced with the permitted FeI+FeII blends at $\sim 4400$Å and $\sim 5400$Å. The $\approx 7300$Å feature, which is produced by [FeII]+[NiII] at $\lesssim 400$days after explosion, is replaced by broad ($\approx \pm 15000\mathrm{km}{\mathrm{s}}^{-1}$) symmetric [CaII] emission. Models predict this ionization transition occurring $\sim 100$ days later than what is observed, which we attribute to clumping in the ejecta. Finally, we use the nebular-phase spectra to test several proposed progenitor scenarios for SN2011fe. Non-detections of H and He exclude nearby non-degenerate companions, [OI] non-detections disfavor the violent merger of two white dwarfs, and the symmetric emission-line profiles favor a symmetric explosion.

8 pages, 1 table, 6 figures. Accepted by ApJL

References in corpus (22)

• The Rising Light Curves of Type Ia Supernovae
• 3D simulations of RS Oph: from accretion to nova blast
• Nebular spectra and abundance tomography of the type Ia supernova SN 2011fe: a normal SN Ia with a stable Fe core
• No trace of a single-degenerate companion in late spectra of SNe 2011fe and 2014J
• Nebular-Phase Spectra of Nearby Type Ia Supernovae
• Monte Carlo radiative transfer for the nebular phase of Type Ia supernovae
• Nebular Models of Sub-Chandrasekhar Mass Type Ia Supernovae: Clues to the Origin of Ca-rich Transients
• Strong Calcium Emission Indicates that the Ultraviolet-Flashing Type Ia SN 2019yvq was the Result of a Sub-Chandrasekhar Mass Double-Detonation Explosion
• Twins for life? A comparative analysis of the Type Ia supernovae 2011fe and 2011by
• Spectroscopy of the Type Ia supernova 2011fe past 1000 days
• The detonation of a sub-Chandrasekhar-mass white dwarf at the origin of the low-luminosity Type Ia supernova 1999by
• Ejecta Mass Diagnostics of Type Ia Supernovae
• Extremely late photometry of SN~2011fe
• A Bright Ultraviolet Excess in the Transitional 02es-like Type Ia Supernova 2019yvq
• Very late photometry of SN 2011fe
• Herschel limits on far-infrared emission from circumstellar dust around nearby Type Ia supernovae
• Measuring an off-Center Detonation through Infrared Line Profiles: The peculiar Type Ia Supernova SN~2020qxp/ASASSN-20jq
• Spectral signatures of H-rich material stripped from a non-degenerate companion by a Type Ia supernova
• SN2019yvq Does Not Conform to SN Ia Explosion Models
• A year-long plateau in the late-time near-infrared light curves of Type Ia supernovae
• The intermediate nebular phase of SN 2014J: onset of clumping as the source of recombination
• Type Ia Supernova Models: Asymmetric Remnants and Supernova Remnant G1.9+0.3

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• From Out of the Blue: Swift Links 2002es-like, 2003fg-like, and Early-Time Bump Type Ia Supernovae
• The origin and evolution of the normal Type Ia SN 2018aoz with infant-phase reddening and excess emission
• The Whisper of a Whimper of a Bang: 2400 Days of the Type Ia SN 2011fe Reveals the Decay of ${}^{55}$Fe
• Origin of high-velocity ejecta and early red excess emission in the infant Type Ia supernova 2021aefx
• Signatures of a surviving helium-star companion in Type Ia supernovae and constraints on the progenitor companion of SN 2011fe
• Near-infrared and Optical Nebular-phase Spectra of Type Ia Supernovae SN 2013aa and SN 2017cbv in NGC 5643
• The HST Non-Detection of SN Ia 2011fe 11.5yr After Explosion Further Restricts Single-Degenerate Progenitor Systems
• Producing type Ia supernovae from hybrid CONe white dwarfs with main-sequence binary companions at low metallicity of Z = 0.0001