The electron-capture origin of supernova 2018zd

Hiramatsu, Daichi; Howell, D. Andrew; Van Dyk, Schuyler D.; Goldberg, Jared A.; Maeda, Keiichi; Moriya, Takashi J.; Tominaga, Nozomu; Nomoto, Ken'ichi; Hosseinzadeh, Griffin; Arcavi, Iair; McCully, Curtis; Burke, Jamison; Bostroem, K. Azalee; Valenti, Stefano; Dong, Yize; Brown, Peter J.; Andrews, Jennifer E.; Bilinski, Christopher; Williams, G. Grant; Smith, Paul S.; Smith, Nathan; Sand, David J.; Anand, Gagandeep S.; Xu, Chengyuan; Filippenko, Alexei V.; Bersten, Melina C.; Folatelli, Gastón; Kelly, Patrick L.; Noguchi, Toshihide; Itagaki, Koichi

doi:10.48550/arxiv.2011.02176

Cited by 8 publications

(9 citation statements)

References 85 publications

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“…It was discovered in NGC 2146 by K. Itagaki on 2018 March 2 (Zhang et al 2018a), and classified initially as a Type IIn SN because of the narrow emission lines in the spectra (Zhang et al 2018b). Zhang et al (2020), Boian & Groh (2020), and Hiramatsu et al (2020) (hereafter Z20, B20 and H20, respectively), have published analysis of SN 2018zd, and we will compare our results to theirs throughout this paper. B20 include SN 2018zd in their sample of SNe with brief, early-time interaction signatures in their spectra, for which they constrain the progenitor and explosion properties by computing early-time spectra using the radiative transfer code (Hillier & Miller 1998).…”

Section: Introductionmentioning

confidence: 79%

How low can you go? SN 2018zd as a low-mass Fe core-collapse supernova

Callis¹,

Fraser²,

Pastorello³

et al. 2021

Preprint

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We present spectroscopy and photometry of SN 2018zd, a Type IIP core-collapse supernova with signatures of interaction with circumstantial material in its earliest spectra. High ionization lines, the earmark of shock breakout, are not seen in the earliest spectral epoch, and are only seen in a single spectrum at 4.9 d after explosion. The strength and brevity of these features imply a confined circumstellar material shell in the immediate vicinity of the progenitor. Once the narrow emission lines disappear, SN 2018zd evolves similarly to a Type IIP SN, although the blue colour and enhanced plateau magnitude of SN 2018zd suggests an additional source of luminosity throughout the plateau phase. While SN 2018zd has previously been proposed as an electron-capture SN, we suggest that it is an Fe core-collapse from a low mass red supergiant progenitor. Differences in interpretation for SN 2018zd arise in part due to the large uncertainty on the distance to the host-galaxy NGC 2146, which we re-derive here to be 15.6 +6.1 −3.0 Mpc. We find the ejected 56 Ni mass for SN 2018zd to be 0.017 M , significantly higher than models of ECSNe predict. We also find the Ni/Fe ratio in SN 2018zd to be much lower that would be expected for an ECSN.

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Section: Introductionmentioning

confidence: 79%

How low can you go? SN 2018zd as a low-mass Fe core-collapse supernova

Callis¹,

Fraser²,

Pastorello³

et al. 2021

Preprint

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show abstract

“…The Precision-Recall curve can also be used as an indicator of prediction confidence. We used this property to provide supplementary evidence that helped Hiramatsu et al (2020) determine a candidate progenitor to be a new type of stellar explosion -an electron-capture supernova. We rule out the presence of cosmic-ray hits at or around the progenitor site to determine the peak pixel is an actual stellar PSF with > 3σ confidence by plotting deepCR's (Zhang & Bloom 2020) predicted score on the corresponding Precision-Recall curve to read the model precision at the progenitor site.…”

Section: Resultsmentioning

confidence: 99%

Cosmic-CoNN: A Cosmic Ray Detection Deep-Learning Framework, Dataset, and Toolkit

McCully²,

Dong³

et al. 2021

Preprint

Self Cite

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Rejecting cosmic rays (CRs) is essential for scientific interpretation of CCD-captured data, but detecting CRs in single-exposure images has remained challenging. Conventional CR-detection algorithms require tuning multiple parameters experimentally, making it hard to automate across different instruments or observation requests. Recent work using deep learning to train CR-detection models has demonstrated promising results. However, instrument-specific models suffer from performance loss on images from ground-based facilities not included in the training data. In this work, we present Cosmic-CoNN, a deep-learning framework designed to produce generic CR-detection models. We build a large, diverse ground-based CR dataset leveraging thousands of images from the Las Cumbres Observatory global telescope network to produce a generic CR-detection model which achieves a 99.91% true-positive detection rate and maintains over 96.40% true-positive rates on unseen data from Gemini GMOS-N/S, with a false-positive rate of 0.01%. Apart from the open-source framework and dataset, we also build a suite of tools including console commands, a web-based application, and Python APIs to make automatic, robust CR detection widely accessible by the community of astronomers.

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“…As one of the scenarios to produce light NSs, an electroncapture supernova of an ONeMg core is suggested and has been confirmed from recent observation. 50 Setting the critical density of ONeMg core as 4.5×10 9 g cm −3 , the baryon mass of ONeMg core just before its collapse is estimated to be 1.375 M . Then, the baryonic mass of formed NS is given as M B 1.375 M .…”

Section: Possible Constraint From the Masses Of Psr J0737−3039(b)mentioning

confidence: 99%

Cooling of Isolated Neutron Stars with Pion Condensation: Possible Fast Cooling in a Low-Symmetry-Energy Model

Dohi,

Liu,

Noda

et al. 2021

Preprint

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We studied thermal evolution of isolated neutron stars (NSs) including the pion condensation core, with an emphasis on the stiffness of equation of state (EOS). Many temperature observations can be explained by the minimal cooling scenario which excludes the fast neutrino cooling process. However, several NSs are cold enough to require it. The most crucial problem for NS cooling theory is whether the nucleon direct Urca (DU) process is open. The DU process is forbidden if the nucleon symmetry energy is significantly low. Hence, another fast cooling process is required in such an EOS. As the candidate to solve this problem, we consider the pion condensation. We show that the low-symmetry-energy model can account for most cooling observations including cold NSs, with strong neutron superfluidity. Simultaneously, it holds the 2 M observations even if the pion condensation core exists. Thus, we propose the possibility of pion condensation, as an exotic state to solve the problem in low-symmetry-energy EOSs. We examined the consistency of our EOSs with other various observations as well.

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The electron-capture origin of supernova 2018zd

Cited by 8 publications

References 85 publications

How low can you go? SN 2018zd as a low-mass Fe core-collapse supernova

How low can you go? SN 2018zd as a low-mass Fe core-collapse supernova

Cosmic-CoNN: A Cosmic Ray Detection Deep-Learning Framework, Dataset, and Toolkit

Cooling of Isolated Neutron Stars with Pion Condensation: Possible Fast Cooling in a Low-Symmetry-Energy Model

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