Discovery of a Fast Iron Low-ionization Outflow in the Early Evolution of the Nearby Tidal Disruption Event AT2019qiz. (arXiv:2011.01593v2 [astro-ph.HE] UPDATED)

Discovery of a Fast Iron Low-ionization Outflow in the Early Evolution of the Nearby Tidal Disruption Event AT2019qiz. (arXiv:2011.01593v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Hung_T/0/1/0/all/0/1">Tiara Hung</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Foley_R/0/1/0/all/0/1">Ryan J. Foley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Veilleux_S/0/1/0/all/0/1">S. Veilleux</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cenko_S/0/1/0/all/0/1">S. B. Cenko</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dai_J/0/1/0/all/0/1">Jane L. Dai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Auchettl_K/0/1/0/all/0/1">Katie Auchettl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brink_T/0/1/0/all/0/1">Thomas G. Brink</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dimitriadis_G/0/1/0/all/0/1">Georgios Dimitriadis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Filippenko_A/0/1/0/all/0/1">Alexei V. Filippenko</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gezari_S/0/1/0/all/0/1">S. Gezari</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Holoien_T/0/1/0/all/0/1">Thomas W.-S. Holoien</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kilpatrick_C/0/1/0/all/0/1">Charles D. Kilpatrick</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mockler_B/0/1/0/all/0/1">Brenna Mockler</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Piro_A/0/1/0/all/0/1">Anthony L. Piro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ramirez_Ruiz_E/0/1/0/all/0/1">Enrico Ramirez-Ruiz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rojas_Bravo_C/0/1/0/all/0/1">César Rojas-Bravo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Siebert_M/0/1/0/all/0/1">Matthew R. Siebert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Velzen_S/0/1/0/all/0/1">Sjoert van Velzen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zheng_W/0/1/0/all/0/1">WeiKang Zheng</a>

We report the results of ultraviolet (UV) and optical photometric and
spectroscopic analysis of the tidal disruption event (TDE) AT2019qiz. Our
follow-up observations started $<$10 days after the source began to brighten in
the optical and lasted for a period of six months. Our late-time host-dominated
spectrum indicates that the host galaxy likely harbors a weak active galactic
nucleus. The initial {it Hubble Space Telescope (HST)} spectrum of AT2019qiz
exhibits an iron and low-ionization broad absorption line (FeLoBAL) system that
is seen for the first time in a TDE. This spectrum also bears a striking
resemblance to that of Gaia16apd, a superluminous supernova. Our observations
provide insights into the outflow properties in TDEs and show evidence for a
connection between TDEs and engine-powered supernovae at early phase, as
originally suggested in Metzger & Stone (2016). In a time frame of 50 days, the
UV spectra of AT2019qiz started to resemble previous TDEs with only
high-ionization BALs. The change in UV spectral signatures is accompanied by a
decrease in the outflow velocity, which began at $15,000$ km s$^{-1}$ and
decelerated to $sim10,000$ km s$^{-1}$. A similar evolution in the H$alpha$
emission line width further supports the speculation that the broad Balmer
emission lines are formed in TDE outflows. In addition, we detect narrow
absorption features on top of the FeLoBAL signatures in the early HST UV
spectrum of AT2019qiz. The measured HI column density corresponds to a
Lyman-limit system whereas the metal absorption lines, such as NV, CIV, FeII,
and MgII, are likely probing the circumnuclear gas and interstellar medium in
the host galaxy.

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