Detection of [C I] Emission in Nebular Spectra of a Peculiar Type Ia Supernova 2022pul

Abstract

SN 2022pul gains special attention due to its possible origin of a super-Chandarsekhar-mass white dwarf explosion (or called a 03fg-like type Ia supernova), which shows prominent [O I], [Ne II], and [Ca II] lines in its late-time spectra taken at $\sim +$300 days after the peak brightness. In this paper, we present new optical observations for this peculiar object, extending up to over 500 days after the peak brightness. In particular, in the $t\approx +515$ days spectrum, we identified for the first time the presence of narrow emission from [C I] $\lambda \lambda 9824,9850$, which appears asymmetric and quite similar to the accompanied [O I] $\lambda 6300$ line in strength and profile. Based on the violent merger model that accounts well for previous observations but leaves little carbon in the center of the ejecta, this carbon line can be reproduced by increasing the degree of clumping in the ejecta and setting the carbon mass the same as that of oxygen ($\sim$0.06 $M_{\odot }$) in the innermost region ($\lesssim 2000$ km s${}^{-1}$). In principle, the central carbon could come from the secondary white dwarf (WD) if it is ignited when hit by the shockwave of the explosion of the primary WD and explodes as a Ca-rich supernova, whereas pure deflagration of a super-Chandarsekhar-mass WD can account for such unburnt carbon more naturally.

arXiv comment8 pages, 6 figures, 2 tables, published in ApJL

References in corpus (41)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• emcee: The MCMC Hammer
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• Type Ia Supernova Explosion Models
• The Reddening-Free Decline Rate Versus Luminosity Relationship for Type Ia Supernovae
• The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star
• Normal Type Ia supernovae from violent mergers of white dwarf binaries
• Nearby Supernova Factory Observations of SN 2007if: First Total Mass Measurement of a Super-Chandrasekhar-Mass Progenitor
• Berkeley Supernova Ia Program I: Observations, Data Reduction, and Spectroscopic Sample of 582 Low-Redshift Type Ia Supernovae
• Three-dimensional pure deflagration models with nucleosynthesis and synthetic observables for Type Ia supernovae
• Remnant evolution after a carbon-oxygen white dwarf merger
• Fully-Automated Reduction of Longslit Spectroscopy with the Low Resolution Imaging Spectrometer at Keck Observatory
• On the evolution of rapidly rotating massive white dwarfs towards supernovae or collapses
• Fourteen Months of Observations of the Possible Super-Chandrasekhar Mass Type Ia Supernova 2009dc
• High luminosity, slow ejecta and persistent carbon lines: SN 2009dc challenges thermonuclear explosion scenarios
• Optical and Near-Infrared Observations of the Highly Reddened, Rapidly Expanding Type Ia Supernova 2006X in M100
• Type Ia Supernovae: Their Origin and Possible Applications in Cosmology
• Time Dependent Radiative Transfer Calculations for Supernovae
• The Xinglong 2.16-m Telescope: Current Instruments and Scientific Projects
• The Rising Light Curves of Type Ia Supernovae
• Three-dimensional modeling of Type Ia supernovae - The power of late time spectra
• Optical Observations of the Type Ia Supernova 2011fe in M101 for Nearly 500 Days
• Gaia Data Release 3: The Galaxy in your preferred colours. Synthetic photometry from Gaia low-resolution spectra
• The Type Ic SN 2007gr: a census of the ejecta from late-time optical-infrared spectra
• Lick Observatory Supernova Search Follow-Up Program: Photometry Data Release of 93 Type Ia Supernovae
• On the fate of the secondary white dwarf in double-degenerate double-detonation Type Ia supernovae
• The Photometric System of Tsinghua-NAOC 80-cm Telescope at NAOC Xinglong Observatory
• Nebular-Phase Spectra of Nearby Type Ia Supernovae
• PESSTO monitoring of SN 2012hn: further heterogeneity among faint type I supernovae
• The Automated Photometry Of Transients (AutoPhOT) pipeline
• Carnegie Supernova Project: The First Homogeneous Sample of "Super-Chandrasekhar Mass"/2003fg-like Type Ia Supernova
• Thermonuclear explosions of rapidly rotating white dwarfs - II. Detonations
• Thermonuclear explosions of rapidly rotating white dwarfs - I. Deflagrations
• The origins of Calcium-rich supernovae from disruptions of CO white-dwarfs by hybrid He-CO white-dwarfs
• SN 2021zny: an early flux excess combined with late-time oxygen emission suggests a double white dwarf merger event
• A Carbon/Oxygen-dominated Atmosphere Days After Explosion for the "Super-Chandrasekhar" Type Ia SN 2020esm
• Ground-based and JWST Observations of SN 2022pul: II. Evidence from Nebular Spectroscopy for a Violent Merger in a Peculiar Type-Ia Supernova
• From Out of the Blue: Swift Links 2002es-like, 2003fg-like, and Early-Time Bump Type Ia Supernovae

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