Coronal Line Emitters are Tidal Disruption Events in Gas-Rich Environments

Some galaxies show little to no sign of active galactic nucleus (AGN) activity, yet exhibit strong coronal emission lines (CLs) relative to common narrow emission lines. Many of these coronal lines have ionization potentials of $\geq 100$ eV, thus requiring strong extreme UV and/or soft X-ray flux. It has long been thought that such events are powered by tidal disruption events (TDEs), but owing to a lack of detailed multi-wavelength follow-up, such a connection has not been firmly made. Here we compare coronal line emitters (CLEs) and TDEs in terms of their host-galaxy and transient properties. We find that the mid-infrared (MIR) colors of CLE hosts in quiescence are similar to TDE hosts. Additionally, many CLEs show evidence of a large dust reprocessing echo in their mid-infrared colors, a sign of significant dust in the nucleus. The stellar masses and star formation rates of the CLE hosts are consistent with TDE hosts, and both populations reside within the green valley. The blackbody properties of CLEs and TDEs are similar, with some CLEs showing hot (T $\geq 40,000$ K) blackbody temperatures. Finally, the location of CLEs on the peak-luminosity/decline-rate parameter space is much closer to TDEs than many other major classes of nuclear transients. Combined, these provide strong evidence to confirm the previous claims that CLEs are indeed TDEs in gas-rich environments. We additionally propose a stricter threshold of CL flux $\geq 1/3$ $\times$ [O III] flux to better exclude AGNs from the sample of CLEs.Comment: 9 pages, 7 figures. Will be submitted to MNRAS. Comments welcom

The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0

The All-Sky Automated Survey for Supernovae (ASAS-SN) is working towards imaging the entire visible sky every night to a depth of V~17 mag. The present data covers the sky and spans ~2-5~years with ~100-400 epochs of observation. The data should contain some ~1 million variable sources, and the ultimate goal is to have a database of these observations publicly accessible. We describe here a first step, a simple but unprecedented web interface https://asas-sn.osu.edu/ that provides an up to date aperture photometry light curve for any user-selected sky coordinate. Because the light curves are produced in real time, this web tool is relatively slow and can only be used for small samples of objects. However, it also imposes no selection bias on the part of the ASAS-SN team, allowing the user to obtain a light curve for any point on the celestial sphere. We present the tool, describe its capabilities, limitations, and known issues, and provide a few illustrative examples.Comment: 8 pages, 9 figures, submitted to PAS