Constraining the Source of the High Velocity Ejecta in the Type Ia SN 2019ein. (arXiv:2003.05946v1 [astro-ph.HE])

Constraining the Source of the High Velocity Ejecta in the Type Ia SN 2019ein. (arXiv:2003.05946v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Pellegrino_C/0/1/0/all/0/1">C. Pellegrino</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Howell_D/0/1/0/all/0/1">D. A. Howell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sarbadhicary_S/0/1/0/all/0/1">S. K. Sarbadhicary</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burke_J/0/1/0/all/0/1">J. Burke</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hiramatsu_D/0/1/0/all/0/1">D. Hiramatsu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McCully_C/0/1/0/all/0/1">C. McCully</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Milne_P/0/1/0/all/0/1">P. A. Milne</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Andrews_J/0/1/0/all/0/1">J. E. Andrews</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brown_P/0/1/0/all/0/1">P. Brown</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chomiuk_L/0/1/0/all/0/1">L. Chomiuk</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hsiao_E/0/1/0/all/0/1">E. Y. Hsiao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sand_D/0/1/0/all/0/1">D. J. Sand</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shahbandeh_M/0/1/0/all/0/1">M. Shahbandeh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Smith_N/0/1/0/all/0/1">N. Smith</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Valenti_S/0/1/0/all/0/1">S. Valenti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vinko_J/0/1/0/all/0/1">J. Vinkó</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wheeler_J/0/1/0/all/0/1">J. C. Wheeler</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wyatt_S/0/1/0/all/0/1">S. Wyatt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yang_Y/0/1/0/all/0/1">Y. Yang</a>

We present multi-wavelength photometric and spectroscopic observations of SN
2019ein, a High Velocity Type Ia supernova discovered in the nearby galaxy NGC
5353 with a two day non-detection limit. SN 2019ein exhibited some of the
highest measured expansion velocities of any Type Ia supernovae, with a Si II
absorption minimum blueshifted by 24,000 km s$^{-1}$ at 14 days before peak
brightness. More unusually, we observed the emission components of the P Cygni
profiles to be blueshifted upwards of 10,000 km s$^{-1}$ with respect to the
host galaxy redshift before B-band maximum light. This blueshift, among the
highest in a sample of other Type Ia supernovae, is greatest at our earliest
spectroscopic epoch and subsequently decreases toward maximum light. We discuss
models of progenitor systems and explosion mechanisms that could explain these
extreme absorption and emission velocities. Radio observations beginning 14
days before B-band maximum light yield non-detections at the position of SN
2019ein, which rules out symbiotic progenitor systems, most models of white
dwarfs powering fast optically-thick accretion winds, and optically thin shells
of mass $lesssim 10^{-6}$ M$_odot$ at radii $< 100$ AU. Comparing our spectra
to models and observations of other High Velocity Type Ia supernovae, we find
that the observational properties of SN 2019ein match those of a delayed
detonation explosion. We propose that the high velocity ejecta and blueshifted
emission may be the result of abundance enhancements due to ejecta mixing in an
asymmetric explosion, or optical depth effects in the photosphere of the ejecta
at early times. These findings may provide evidence for common explosion
mechanisms and ejecta geometries among High Velocity Type Ia supernovae.

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