The Spectroscopic Classification of Astronomical Transients (SCAT) Survey: Overview, Pipeline Description, Initial Results, and Future Plans

Tucker, M. A.; Shappee, B. J.; Huber, M. E.; Payne, A. V.; Do, A.; Hinkle, J.; Jaeger, Thomas de; Ashall, C.; Desai, D.; Hoogendam, W. B.; Aldering, G.; Auchettl, Katie; Baranec, Christoph; Bulger, J.; Chambers, K.; Chun, Mark; Hodapp, K. W.; McKay, L.; Rampy, R.; Rubin, D.; Tonry, J.

doi:10.1088/1538-3873/aca719

Cited by 21 publications

(8 citation statements)

References 77 publications

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“…Like other 03fg-like SNe, this SN has a large spatial offset from its host galaxy, possibly indicating that it could have originated in a low-metallicity environment (Khan et al 2011). SN 2022pul was quickly classified as an SN Ia by the Spectroscopic Classification of Astronomical Transients Survey (Tucker et al 2022b) on 2022 August 1.…”

Section: Introductionmentioning

confidence: 99%

Ground-based and JWST Observations of SN 2022pul. I. Unusual Signatures of Carbon, Oxygen, and Circumstellar Interaction in a Peculiar Type Ia Supernova

Siebert,

Kwok,

Johansson

et al. 2023

ApJ

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Nebular-phase observations of peculiar Type Ia supernovae (SNe Ia) provide important constraints on progenitor scenarios and explosion dynamics for both these rare SNe and the more common, cosmologically useful SNe Ia. We present observations from an extensive ground- and space-based follow-up campaign to characterize SN 2022pul, a super-Chandrasekhar mass SN Ia (alternatively “03fg-like” SN), from before peak brightness to well into the nebular phase across optical to mid-infrared (MIR) wavelengths. The early rise of the light curve is atypical, exhibiting two distinct components, consistent with SN Ia ejecta interacting with dense carbon–oxygen (C/O)-rich circumstellar material (CSM). In the optical, SN 2022pul is most similar to SN 2012dn, having a low estimated peak luminosity (M B = −18.9 mag) and high photospheric velocity relative to other 03fg-like SNe. In the nebular phase, SN 2022pul adds to the increasing diversity of the 03fg-like subclass. From 168 to 336 days after peak B-band brightness, SN 2022pul exhibits asymmetric and narrow emission from [O i] λ λ6300, 6364 (FWHM ≈ 2000 km s−1), strong, broad emission from [Ca ii] λ λ7291, 7323 (FWHM ≈ 7300 km s−1), and a rapid Fe iii to Fe ii ionization change. Finally, we present the first ever optical-to-MIR nebular spectrum of an 03fg-like SN Ia using data from JWST. In the MIR, strong lines of neon and argon, weak emission from stable nickel, and strong thermal dust emission (with T ≈ 500 K), combined with prominent [O i] in the optical, suggest that SN 2022pul was produced by a white dwarf merger within C/O-rich CSM.

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Section: Introductionmentioning

confidence: 99%

Ground-based and JWST Observations of SN 2022pul. I. Unusual Signatures of Carbon, Oxygen, and Circumstellar Interaction in a Peculiar Type Ia Supernova

Siebert,

Kwok,

Johansson

et al. 2023

ApJ

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“…We obtained optical spectra of AT 2022aedm using EFOSC2 on the NTT (through ePESSTO+), the LCO 2 m telescopes, the SuperNova Integral Field Spectrograph (Lantz et al 2004;Tucker et al 2022) on the University of Hawaii 2.2 m telescope, and Binospec on the 6.5 m MMT (Fabricant et al 2019). Spectroscopy from ePESSTO+ commenced on 2022 December 31 (within a day after the object was flagged by ATLAS) and continued until 2023 February 20, by which time the spectrum was indistinguishable from a preexplosion host galaxy spectrum from SDSS.…”

Section: Spectroscopymentioning

confidence: 99%

AT 2022aedm and a New Class of Luminous, Fast-cooling Transients in Elliptical Galaxies

Nicholl,

Srivastav,

Fulton

et al. 2023

ApJL

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We present the discovery and extensive follow-up of a remarkable fast-evolving optical transient, AT 2022aedm, detected by the Asteroid Terrestrial impact Last Alert Survey (ATLAS). In the ATLAS o band, AT 2022aedm exhibited a rise time of 9 ± 1 days, reaching a luminous peak with M g ≈ −22 mag. It faded by 2 mag in the g band during the next 15 days. These timescales are consistent with other rapidly evolving transients, though the luminosity is extreme. Most surprisingly, the host galaxy is a massive elliptical with negligible current star formation. Radio and X-ray observations rule out a relativistic AT 2018cow–like explosion. A spectrum in the first few days after explosion showed short-lived He ii emission resembling young core-collapse supernovae, but obvious broad supernova features never developed; later spectra showed only a fast-cooling continuum and narrow, blueshifted absorption lines, possibly arising in a wind with v ≈ 2700 km s−1. We identify two further transients in the literature (Dougie in particular, as well as AT 2020bot) that share similarities in their luminosities, timescales, color evolution, and largely featureless spectra and propose that these may constitute a new class of transients: luminous fast coolers. All three events occurred in passive galaxies at offsets of ∼4–10 kpc from the nucleus, posing a challenge for progenitor models involving massive stars or black holes. The light curves and spectra appear to be consistent with shock breakout emission, though this mechanism is usually associated with core-collapse supernovae. The encounter of a star with a stellar-mass black hole may provide a promising alternative explanation.

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“…One epoch from the University of Hawaii 2.2 m telescope was obtained on 2022 July 24.62 (MJD 59784.62) using SNIFS (Lantz et al 2004). The SNIFS spectrum was reduced using the Spectroscopic Classification of Astronomical Transients (SCAT) survey pipeline (Tucker et al 2022).…”

Section: Spectroscopymentioning

confidence: 99%

SN 2022jli: A Type Ic Supernova with Periodic Modulation of Its Light Curve and an Unusually Long Rise

Moore,

Smartt,

Nicholl

et al. 2023

ApJL

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We present multiwavelength photometry and spectroscopy of SN 2022jli, an unprecedented Type Ic supernova discovered in the galaxy NGC 157 at a distance of ≈ 23 Mpc. The multiband light curves reveal many remarkable characteristics. Peaking at a magnitude of g = 15.11 ± 0.02, the high-cadence photometry reveals periodic undulations of 12.5 ± 0.2 days superimposed on the 200-day supernova decline. This periodicity is observed in the light curves from nine separate filter and instrument configurations with peak-to-peak amplitudes of ≃ 0.1 mag. This is the first time that repeated periodic oscillations, over many cycles, have been detected in a supernova light curve. SN 2022jli also displays an extreme early excess that fades over ≈25 days, followed by a rise to a peak luminosity of L opt = 1042.1 erg s−1. Although the exact explosion epoch is not constrained by data, the time from explosion to maximum light is ≳ 59 days. The luminosity can be explained by a large ejecta mass (M ej ≈ 12 ± 6 M ⊙) powered by 56Ni, but we find it difficult to quantitatively model the early excess with circumstellar interaction and cooling. Collision between the supernova ejecta and a binary companion is a possible source of this emission. We discuss the origin of the periodic variability in the light curve, including interaction of the SN ejecta with nested shells of circumstellar matter and neutron stars colliding with binary companions.

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The Spectroscopic Classification of Astronomical Transients (SCAT) Survey: Overview, Pipeline Description, Initial Results, and Future Plans

Cited by 21 publications

References 77 publications

Ground-based and JWST Observations of SN 2022pul. I. Unusual Signatures of Carbon, Oxygen, and Circumstellar Interaction in a Peculiar Type Ia Supernova

Ground-based and JWST Observations of SN 2022pul. I. Unusual Signatures of Carbon, Oxygen, and Circumstellar Interaction in a Peculiar Type Ia Supernova

AT 2022aedm and a New Class of Luminous, Fast-cooling Transients in Elliptical Galaxies

SN 2022jli: A Type Ic Supernova with Periodic Modulation of Its Light Curve and an Unusually Long Rise

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