Speaker
Description
Extreme coronal line emitters (ECLEs) are a composite population of tidal disruption events (TDEs) and exotic active galactic nuclei (AGNs) displaying emission lines from highly ionised iron (FeVII - FeXIV). These lines are produced through the reprocessing of high energy X-ray photons by gas-rich environments. The TDE-linked subpopulation of these events also displays a distinctive mid-infrared flaring behaviour through additional emission reprocessing and show temporal evolution, returning to their quiescent / pre-outburst properties on timescales of years - decades. As such, ECLEs provide a unique opportunity to explore gas rich nuclear environments of both quiescent and active supermassive black holes.
Here I will report on the search for these objects within the early data release (EDR) of the Dark Energy Spectroscopic Instrument (DESI). DESI's goal of obtaining a vast number of spectroscopic redshifts of galaxies across the northern sky makes it an excellent tool in the search for ECLEs which given their rarity (~ 2×10−9 Mpc−3 yr−1) necessitate the use of large-scale surveys for discovery.
In my talk, I will summarise the ECLE search within DESI EDR, highlight the most promising objects identified (including detailing the follow-up observations conducted) and provide context into how this newly identified sample compares to our existing samples of ECLEs, TDEs and exotic AGN. I will also present the most current rate estimates of these objects based on the DESI search in combination with previous analyses based on SDSS and BOSS samples.
