SN 2019ein: New Insights into the Similarities and Diversity among High-velocity Type Ia Supernovae

Kawabata, Miho; Maeda, Keiichi; Yamanaka, Masahito; Nakaoka, Tatsuya; Kawabata, Koji S.; Adachi, R.; Akitaya, Hiroshi; Burgaz, U.; Hanayama, H.; Horiuchi, Takashi; Hosokawa, R.; Iida, Katsuyoshi; Imazato, Fumiya; Isogai, Keisuke; Jiang, Ji-an; Katoh, Noriyuki; Kimura, Hiroki; Kino, Motoki; Kuroda, D.; Maehara, Hiroyuki; Matsubayashi, Kazuya; Morihana, K.; Murata, Katsuhiro L.; Nagao, Takashi; Niwano, Masafumi; Nogami, Daisaku; Oeda, M.; Ono, T.; Onozato, Hiroki; Otsuka, Masaaki; Saito, Tomoki; Sasada, Mahito; Shiraishi, K.; Sugiyama, H.; Taguchi, Kenta; Takahashi, Jun; Takagi, Kengo; Takagi, Seiko; Takayama, Masaki; Tozuka, Miyako; Sekiguchi, Kazuhiko

doi:10.3847/1538-4357/ab8236

Cited by 27 publications

(25 citation statements)

References 118 publications

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“…6), reaching a maximum at around the second light curve peak observed in the ZTF r -band. SN 2019ein has the highest recorded expansion velocities for a Type Ia SN at early times (Kawabata et al 2020;Pellegrino et al 2020). SN 2019ein also exhibited blue-shifted line profiles in early spectra (at -14 d relative to B-band maximum light), in particular for the strong Si II feature.…”

Section: Discussion and C O N C L U S I O N Smentioning

confidence: 94%

RINGO3 polarimetry of very young ZTF supernovae

Maund

Yang

Steele

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The early phases of the observed evolution of the supernovae (SNe) are expected to be dominated by the shock breakout and ‘flash’ ionization of the surrounding circumstellar medium. This material arises from the last stages of the evolution of the progenitor, such that photometry and spectroscopy of SNe at early times can place vital constraints on the latest and fastest evolutionary phases leading up to stellar death. These signatures are erased by the expansion of the ejecta within ∼5 days after explosion. Here we present the earliest constraints, to date, on the polarization of ten transients discovered by the Zwicky Transient Facility (ZTF), between June 2018 and August 2019. Rapid polarimetric followup was conducted using the Liverpool Telescope RINGO3 instrument, including 3 SNe observed within <1 day of detection by the ZTF. The limits on the polarization within the first 5 days of explosion, for all SN types, is generally $<2{{\ \rm per\ cent}}$, implying early asymmetries are limited to axial ratios >0.65 (assuming an oblate spheroidal configuration). We also present polarimetric observations of the Type I Superluminous SN 2018bsz and Type II SN 2018hna, observed around and after maximum light.

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Section: Discussion and C O N C L U S I O N Smentioning

confidence: 94%

RINGO3 polarimetry of very young ZTF supernovae

Maund

Yang

Steele

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…The polarization and position angle measurements of the two high-polarization standards observed on each night were respectively found to be within 0.1% and 3 • of the references (Schmidt et al 1992;Wolff et al 1996). (Kawabata et al 2020).…”

Section: Polarimetric Calibrationmentioning

confidence: 60%

“…An upper limit of the ISP from the host galaxy of SN 2019ein (NGC 5353) can be estimated based on the host reddening 𝐸 (𝐵 − 𝑉) host = 0.09 ± 0.02 mag (Kawabata et al 2020). Accounting for both the Galactic and SN 2019ein-host dust, we place an upper limit of 𝑝 ISP < 0.9% along the SN-Earth line of sight.…”

Section: Interstellar Polarizationmentioning

confidence: 90%

“…Owing to the sparsely sampled spectropolarimetry, we adopt the peak Si 𝜆6355 polarization measured at day −4 for SN 2019ein. The 𝐵band light-curve decline rate of SN 2019ein has been determined as Δ𝑚 15 (𝐵) = 1.36 ± 0.02 mag (Kawabata et al 2020) and Δ𝑚 15 (𝐵) = 5 The peak of the Si 𝜆6355 polarization is measured between roughly days −11 and +1 (Cikota et al 2019) 1.40±0.004 mag (Pellegrino et al 2020). We infer that SN 2019ein is consistent with the Δ𝑚 15 (𝐵)-𝑝 corr−5 SiII relation as presented by Wang et al (2007) and Cikota et al (2019).…”

Section: The Si 𝜆6355 Polarization Compared With a Larger Samplementioning

confidence: 99%

“…Pellegrino et al (2020) suggested that the apparent blueshift may be caused by an asymmetric explosion resulting in enhanced abundance of material at high velocities or due to optical-depth effects in the photosphere, in which most of the flux comes from material moving along the SN-Earth line of sight. The rise time of SN 2019ein was short (15.37±0.55 days), after which the SN faded rapidly with a 15 day post-peak 𝐵-band magnitude decline (Phillips 1993) Δ𝑚 15 (𝐵) = 1.36 ± 0.02 mag (Kawabata et al 2020).…”

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confidence: 99%

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Spectropolarimetry of the Type Ia SN 2019ein rules out significant global asphericity of the ejecta

Patra,

Yang,

Brink

et al. 2021

Preprint

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Detailed spectropolarimetric studies may hold the key to probing the explosion mechanisms and the progenitor scenarios of Type Ia supernovae (SNe Ia). We present multi-epoch spectropolarimetry and imaging polarimetry of SN 2019ein, an SN Ia showing high expansion velocities at early phases. The spectropolarimetry sequence spans from ∼ −11 to +10 days relative to peak brightness in the 𝐵-band. We find that the level of the continuum polarization of SN 2019ein, after subtracting estimated interstellar polarization, is in the range 0.0-0.3%, typical for SNe Ia. The polarization position angle remains roughly constant before and after the SN light-curve peak, implying that the inner regions share the same axisymmetry as the outer layers. We observe high polarization (∼ 1%) across both the Si 𝜆6355 and Ca near-infrared triplet features. These two lines also display complex polarization modulations. The spectropolarimetric properties of SN 2019ein rule out a significant departure from spherical symmetry of the ejecta for up to a month after the explosion. These observations disfavour merger-induced and double-detonation models for SN 2019ein. The imaging polarimetry shows weak evidence for a modest increase in polarization after ∼ 20 days since the 𝐵-band maximum. If this rise is real and is observed in other SNe Ia at similar phases, we may have seen, for the first time, an aspherical interior similar to what has been previously observed for SNe IIP. Future polarization observations of SNe Ia extending to post-peak epochs will help to examine the inner structure of the explosion.

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The Pantheon+ analysis: Improving the redshifts and peculiar velocities of Type Ia supernovae used in cosmological analyses

Carr

Davis

Scolnic

et al. 2022

Publ. Astron. Soc. Aust.

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We examine the redshifts of a comprehensive set of published Type Ia supernovae, and provide a combined, improved catalogue with updated redshifts. We improve on the original catalogues by using the most up-to-date heliocentric redshift data available; ensuring all redshifts have uncertainty estimates; using the exact formulae to convert heliocentric redshifts into the Cosmic Microwave Background (CMB) frame; and utilising an improved peculiar velocity model that calculates local motions in redshift-space and more realistically accounts for the external bulk flow at high-redshifts. We review 2607 supernova redshifts; 2285 are from unique supernovae and 322 are from repeat-observations of the same supernova. In total, we updated 990 unique heliocentric redshifts, and found 5 cases of missing or incorrect heliocentric corrections, 44 incorrect or missing supernova coordinates, 230 missing heliocentric or CMB frame redshifts, and 1200 missing redshift uncertainties. The absolute corrections range between $10^{-8} \leq \Delta z \leq 0.038$ , and RMS $(\Delta z) \sim 3{\times 10^{-3}}$ . The sign of the correction was essentially random, so the mean and median corrections are small: $4{\times 10^{-4}}$ and $4{\times 10^{-6}}$ respectively. We examine the impact of these improvements for $H_0$ and the dark energy equation of state w and find that the cosmological results change by $\Delta H_0 = -0.12\,\mathrm{km\,s}^{-1}\mathrm{Mpc}^{-1}$ and $\Delta w = 0.003$ , both significantly smaller than previously reported uncertainties for $H_0$ of 1.0 $\mathrm{km\,s}^{-1}\mathrm{Mpc}^{-1}$ and w of 0.04 respectively.

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SN 2019ein: New Insights into the Similarities and Diversity among High-velocity Type Ia Supernovae

Cited by 27 publications

References 118 publications

RINGO3 polarimetry of very young ZTF supernovae

RINGO3 polarimetry of very young ZTF supernovae

Spectropolarimetry of the Type Ia SN 2019ein rules out significant global asphericity of the ejecta

The Pantheon+ analysis: Improving the redshifts and peculiar velocities of Type Ia supernovae used in cosmological analyses

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