Caltech-NRAO Stripe 82 Survey (CNSS). III: The First Radio-discovered Tidal Disruption Event, CNSS J0019+00. (arXiv:1910.11912v2 [astro-ph.HE] UPDATED)

Caltech-NRAO Stripe 82 Survey (CNSS). III: The First Radio-discovered Tidal Disruption Event, CNSS J0019+00. (arXiv:1910.11912v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Anderson_M/0/1/0/all/0/1">M. M. Anderson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mooley_K/0/1/0/all/0/1">K. P. Mooley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hallinan_G/0/1/0/all/0/1">G. Hallinan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dong_D/0/1/0/all/0/1">D. Dong</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Phinney_E/0/1/0/all/0/1">E. S. Phinney</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Horesh_A/0/1/0/all/0/1">A. Horesh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bourke_S/0/1/0/all/0/1">S. Bourke</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:+Frail_D/0/1/0/all/0/1">D. Frail</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kulkarni_S/0/1/0/all/0/1">S. R. Kulkarni</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Myers_S/0/1/0/all/0/1">S. Myers</a>

We present the discovery of a nuclear transient with the Caltech-NRAO Stripe
82 Survey (CNSS), a dedicated radio transient survey carried out with the Karl
G. Jansky Very Large Array (VLA). This transient, CNSS J001947.3+003527,
exhibited a turn-on over a timescale of $lesssim$1 yr, increasing in flux
density at 3 GHz from $<0.14$ mJy in 2014 February to $4.4pm0.1$ mJy in 2015
March, reaching a peak luminosity of $5times10^{28} text{erg s}^{-1}
text{Hz}^{-1}$ around 2015 October. The association of CNSS J0019+00 with the
nucleus (Gaia and our VLBI positions are consistent to within 1 pc) of a nearby
S0 Seyfert galaxy at 77 Mpc, together with the radio spectral evolution,
implies that this transient is most likely a tidal disruption event (TDE). Our
equipartition analysis indicates the presence of a $sim$15,000 km s$^{-1}$
outflow, having energy $sim$10$^{49}$ erg. We derive the radial density
profile for the circumnuclear material in the host galaxy to be proportional to
$R^{-2.5}$. All of these properties suggest resemblance with radio-detected
thermal TDEs like ASASSN-14li and XMMSL1 J0740-85. No significant X-ray or
optical emission is detected from CNSS J0019+00, although this may simply be
due to the thermal emission being weak during our late-time follow-up
observations. From the CNSS survey we have obtained the first unbiased
measurement of the rate of radio TDEs, $R(>500 mu{rm Jy})$ of about
$2times10^{-3}$ deg$^{-2}$, or equivalently a volumetric rate of about 10
Gpc$^{-3}$ yr$^{-1}$. This rate implies that all-sky radio surveys such as the
VLA Sky Survey and those planned with ASKAP, will find many tens of radio TDEs
over the next few years.

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