2025ApJS..280...57D

We conduct the first systematic survey of a total of 11 optical coronal lines (CLs) in the spectra of a large sample of low-redshift (z < 0.8) Type 1 quasars observed by the Sloan Digital Sky Survey (SDSS). We find that strong CL emission is rare in SDSS even in Type 1 quasars; only 885 out of 19,508 (4.5%) galaxies show at least one CL, with higher ionization potential lines (>100 eV) being even rarer. The [Ne V] λ3426 line, which constitutes the majority of detections, is strongly correlated with the bolometric luminosity. These findings suggest that the optical CLs are significantly suppressed in the majority of local active galactic nuclei (AGNs), possibly as a result of the presence of dust in the emitting regions. We find that the incidence of ionized outflows is significantly higher in CL emitters compared with non-CL emitters, possibly suggesting that dust destruction in outflows enhances CL emission in AGNs. Many CLs show line profiles that are broader than those of narrow lines, and are blueshifted relative to the lower ionization potential lines, suggesting outflows in the highly ionized gas. Given the limited number of detections, we do not find any statistically significant trends in detection statistics or line ratios with black hole mass, Eddington ratio, or AGN bolometric luminosity. The catalog is publicly available and can provide a useful database of the CL properties of low-redshift quasars that can be compared to the growing number of high-z AGNs discovered by JWST.