The Rise and Fall of ASASSN-18pg: Following a TDE from Early To Late Times. (arXiv:2003.13693v1 [astro-ph.HE])

The Rise and Fall of ASASSN-18pg: Following a TDE from Early To Late Times. (arXiv:2003.13693v1 [astro-ph.HE])
<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:+Auchettl_K/0/1/0/all/0/1">Katie Auchettl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tucker_M/0/1/0/all/0/1">Michael A. Tucker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shappee_B/0/1/0/all/0/1">Benjamin J. Shappee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Patel_S/0/1/0/all/0/1">Shannon G. Patel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miller_Jones_J/0/1/0/all/0/1">James C. A. Miller-Jones</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:+Groenewald_D/0/1/0/all/0/1">Danièl N. Groenewald</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brown_J/0/1/0/all/0/1">Jonathan S. Brown</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kochanek_C/0/1/0/all/0/1">Christopher S. Kochanek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stanek_K/0/1/0/all/0/1">K. Z. Stanek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_P/0/1/0/all/0/1">Ping Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dong_S/0/1/0/all/0/1">Subo Dong</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prieto_J/0/1/0/all/0/1">Jose L. Prieto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Thompson_T/0/1/0/all/0/1">Todd A. Thompson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beaton_R/0/1/0/all/0/1">Rachael L. Beaton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Connor_T/0/1/0/all/0/1">Thomas Connor</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cowperthwaite_P/0/1/0/all/0/1">Philip S. Cowperthwaite</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dahmen_L/0/1/0/all/0/1">Linnea Dahmen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+French_K/0/1/0/all/0/1">K. Decker French</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Morrell_N/0/1/0/all/0/1">Nidia Morrell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Buckley_D/0/1/0/all/0/1">David A. H. Buckley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gromadzki_M/0/1/0/all/0/1">Mariusz Gromadzki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Roy_R/0/1/0/all/0/1">Rupak Roy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Coulter_D/0/1/0/all/0/1">David A. Coulter</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:+Foley_R/0/1/0/all/0/1">Ryan J. Foley</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:+Piro_A/0/1/0/all/0/1">Anthony L. Piro</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>

We present nearly 500 days of observations of the tidal disruption event
ASASSN-18pg, spanning from 54 days before peak light to 441 days after peak
light. Our dataset includes X-ray, UV, and optical photometry, optical
spectroscopy, radio observations, and the first published spectropolarimetric
observations of a TDE. ASASSN-18pg was discovered on 2018 July 11 by the
All-Sky Automated Survey for Supernovae (ASAS-SN) at a distance of $d=78.6$
Mpc, and with a peak UV magnitude of $msimeq14$ it is both one of the nearest
and brightest TDEs discovered to-date. The photometric data allow us to track
both the rise to peak and the long-term evolution of the TDE. ASASSN-18pg
peaked at a luminosity of $Lsimeq2.2times10^{44}$ erg s$^{-1}$, and its
late-time evolution is shallower than a flux $propto t^{-5/3}$ power-law
model, similar to what has been seen in other TDEs. ASASSN-18pg exhibited
Balmer lines and spectroscopic features consistent with Bowen fluorescence
prior to peak which remained detectable for roughly 225 days after peak.
Analysis of the two-component H$alpha$ profile indicates that, if they are the
result of reprocessing of emission from the accretion disk, the different
spectroscopic lines may be coming from regions between $sim10$ and $sim60$
light-days from the black hole. No X-ray emission is detected from the TDE and
there is no evidence of a jet or strong outflow detected in the radio. Our
spectropolarimetric observations give no strong evidence for significant
asphericity in the emission region, with the emission region having an axis
ratio of at least $sim0.65$.

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