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Late-time Observations of Calcium-rich Transient SN 2019ehk Reveal a Pure Radioactive Decay Power Source

Jacobson-Galán, Wynn V. ; Margutti, Raffaella ; Kilpatrick, Charles D. ; Raymond, John ; Berger, Edo ; Blanchard, Peter K. ; Bobrick, Alexey LU orcid ; Foley, Ryan J. ; Gomez, Sebastian and Hosseinzadeh, Griffin , et al. (2021) In Astrophysical Journal Letters 908(2).
Abstract

We present multiband Hubble Space Telescope imaging of the calcium-rich supernova (SN) SN 2019ehk at 276-389 days after explosion. These observations represent the latest B-band to near-IR photometric measurements of a calcium-rich transient to date and allow for the first opportunity to analyze the late-time bolometric evolution of an object in this observational SN class. We find that the late-time bolometric light curve of SN 2019ehk can be described predominantly through the radioactive decay of 56Co for which we derive a mass of M(56Co) = (2.8 ± 0.1) × 10-2 M o. Furthermore, the rate of decline in bolometric luminosity requires the leakage of γ-rays on timescale t γ = 53.9 ± 1.30 days, but we find no statistical evidence for... (More)

We present multiband Hubble Space Telescope imaging of the calcium-rich supernova (SN) SN 2019ehk at 276-389 days after explosion. These observations represent the latest B-band to near-IR photometric measurements of a calcium-rich transient to date and allow for the first opportunity to analyze the late-time bolometric evolution of an object in this observational SN class. We find that the late-time bolometric light curve of SN 2019ehk can be described predominantly through the radioactive decay of 56Co for which we derive a mass of M(56Co) = (2.8 ± 0.1) × 10-2 M o. Furthermore, the rate of decline in bolometric luminosity requires the leakage of γ-rays on timescale t γ = 53.9 ± 1.30 days, but we find no statistical evidence for incomplete positron trapping in the SN ejecta. While our observations cannot constrain the exact masses of other radioactive isotopes synthesized in SN 2019ehk, we estimate a mass ratio limit of M(57Co)/M(56Co) ≤ 0.030. This limit is consistent with the explosive nucleosynthesis produced in the merger of low-mass white dwarfs, which is one of the favored progenitor scenarios in early-time studies of SN 2019ehk.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Astrophysical Journal Letters
volume
908
issue
2
article number
L32
publisher
IOP Publishing
external identifiers
  • scopus:85102374776
ISSN
2041-8205
DOI
10.3847/2041-8213/abdebc
language
English
LU publication?
yes
id
87f5c74a-21db-4204-ab92-a2731fa117c7
date added to LUP
2021-03-26 08:54:04
date last changed
2024-04-18 04:26:40
@article{87f5c74a-21db-4204-ab92-a2731fa117c7,
  abstract     = {{<p>We present multiband Hubble Space Telescope imaging of the calcium-rich supernova (SN) SN 2019ehk at 276-389 days after explosion. These observations represent the latest B-band to near-IR photometric measurements of a calcium-rich transient to date and allow for the first opportunity to analyze the late-time bolometric evolution of an object in this observational SN class. We find that the late-time bolometric light curve of SN 2019ehk can be described predominantly through the radioactive decay of 56Co for which we derive a mass of M(56Co) = (2.8 ± 0.1) × 10-2 M o. Furthermore, the rate of decline in bolometric luminosity requires the leakage of γ-rays on timescale t γ = 53.9 ± 1.30 days, but we find no statistical evidence for incomplete positron trapping in the SN ejecta. While our observations cannot constrain the exact masses of other radioactive isotopes synthesized in SN 2019ehk, we estimate a mass ratio limit of M(57Co)/M(56Co) ≤ 0.030. This limit is consistent with the explosive nucleosynthesis produced in the merger of low-mass white dwarfs, which is one of the favored progenitor scenarios in early-time studies of SN 2019ehk. </p>}},
  author       = {{Jacobson-Galán, Wynn V. and Margutti, Raffaella and Kilpatrick, Charles D. and Raymond, John and Berger, Edo and Blanchard, Peter K. and Bobrick, Alexey and Foley, Ryan J. and Gomez, Sebastian and Hosseinzadeh, Griffin and Milisavljevic, Danny and Perets, Hagai and Terreran, Giacomo and Zenati, Yossef}},
  issn         = {{2041-8205}},
  language     = {{eng}},
  number       = {{2}},
  publisher    = {{IOP Publishing}},
  series       = {{Astrophysical Journal Letters}},
  title        = {{Late-time Observations of Calcium-rich Transient SN 2019ehk Reveal a Pure Radioactive Decay Power Source}},
  url          = {{http://dx.doi.org/10.3847/2041-8213/abdebc}},
  doi          = {{10.3847/2041-8213/abdebc}},
  volume       = {{908}},
  year         = {{2021}},
}