Discovery and Follow-up of ASASSN-19dj: An X-ray and UV Luminous TDE in an Extreme Post-Starburst Galaxy. (arXiv:2006.06690v1 [astro-ph.HE])

Discovery and Follow-up of ASASSN-19dj: An X-ray and UV Luminous TDE in an Extreme Post-Starburst Galaxy. (arXiv:2006.06690v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Hinkle_J/0/1/0/all/0/1">Jason T. Hinkle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Holoien_T/0/1/0/all/0/1">T. W.-S. Holoien</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Auchettl_K/0/1/0/all/0/1">K. Auchettl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shappee_B/0/1/0/all/0/1">B. J. Shappee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Neustadt_J/0/1/0/all/0/1">J. M. M. Neustadt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Payne_A/0/1/0/all/0/1">A. V. Payne</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brown_J/0/1/0/all/0/1">J. S. Brown</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kochanek_C/0/1/0/all/0/1">C. 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:+Graham_M/0/1/0/all/0/1">M. J. Graham</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tucker_M/0/1/0/all/0/1">M. A. Tucker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Do_A/0/1/0/all/0/1">A. Do</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Anderson_J/0/1/0/all/0/1">J. P. Anderson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bose_S/0/1/0/all/0/1">S. Bose</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_P/0/1/0/all/0/1">P. Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Coulter_D/0/1/0/all/0/1">D. A. Coulter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dimitriadis_G/0/1/0/all/0/1">G. Dimitriadis</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:+Foley_R/0/1/0/all/0/1">R. J. Foley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Huber_M/0/1/0/all/0/1">M. E. Huber</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hung_T/0/1/0/all/0/1">T. Hung</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kilpatrick_C/0/1/0/all/0/1">C. D. Kilpatrick</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pignata_G/0/1/0/all/0/1">G. Pignata</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prieto_J/0/1/0/all/0/1">J. L. Prieto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rojas_Bravo_C/0/1/0/all/0/1">C. Rojas-Bravo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Siebert_M/0/1/0/all/0/1">M. R. Siebert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stalder_B/0/1/0/all/0/1">B. Stalder</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:+Tonry_J/0/1/0/all/0/1">J. L. Tonry</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vallely_P/0/1/0/all/0/1">P. J. Vallely</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wisniewski_J/0/1/0/all/0/1">J. P. Wisniewski</a>

We present observations of ASASSN-19dj, a nearby tidal disruption event (TDE)
discovered in the post-starburst galaxy KUG 0810+227 by the All-Sky Automated
Survey for Supernovae (ASAS-SN) at a distance of d $simeq$ 98 Mpc. We observed
ASASSN-19dj from $-$21 to 392 days relative to peak UV/optical emission using
high-cadence, multi-wavelength spectroscopy and photometry. From the ASAS-SN
$g$-band data, we determine that the TDE began to brighten on 2019 February 6.8
and for the first 25 days the rise was consistent with a flux $propto$ $t^2$
power-law. ASASSN-19dj peaked in the UV/optical on 2019 March 6.5 (MJD =
58548.5) at a bolometric luminosity of $L = (6.2 pm 0.2) times 10^{44} text{
erg s}^{-1}$. Initially remaining roughly constant in X-rays and slowly fading
in the UV/optical, the X-ray flux increased by over an order of magnitude
$sim$225 days after peak, resulting from the expansion of the X-ray emitting
surface. The late-time X-ray emission is well-fit by a blackbody with an
effective radius of $sim 1 times 10^{12} text{ cm}$ and a temperature of
$sim 6 times 10^{5} text{ K}$. Analysis of Catalina Real-Time Transient
Survey images reveals a nuclear outburst roughly 14.5 years earlier with a
smooth decline and a luminosity of $L_V$ $geq$ $1.4 times 10^{43}$ erg
s$^{-1}$, although the nature of the flare is unknown. ASASSN-19dj occurred in
the most extreme post-starburst galaxy yet to host a TDE, with Lick
H$delta_{A}$ = $7.67 pm 0.17$ AA.

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