Search for: All records

Abstract We present a reverberation mapping (RM) analysis of the coronal line [Nev]λ3427-emitting region of the quasar COS168 (SDSS J095910.30+020732.2). [Nev]λ3427 is known as one of the “coronal lines,” which are a species of emission lines present in active galactic nuclei (AGN) spectra with high ionization potentials (≥ 100 eV) that can serve as tracers for AGN activity. The spatial extent of the coronal line region has been studied with only spatial resolving techniques that are not sensitive to the innermost regions of AGN. Through our RM analysis of [Nev]λ3427, we measure a nominal “optimal emission radius” for [Nev]λ3427 of $381.1_{-22}^{+16}$ lt-day (observed frame). We place the coronal line region in context with other AGN regions by comparing it with the characteristic radius of Hα, the dust-sublimation radius, and the dusty torus. The coronal line region is located at a larger radius from the black hole than the characteristic radius of the dusty torus, measured using a torus–radius luminosity relationship. The virial product (v²R/G) of both Hαand [Nev]λ3427 is consistent within the uncertainties, implying that the coronal line region, as probed by the [Nev]λ3427 line, may be in a virialized orbit that is dominated by the gravitational potential of the black hole. This plausibly suggests that coronal lines could be an effective method for estimating black hole masses. 

We present a velocity-resolved reverberation mapping analysis of the hypervariable quasar RM160 (SDSS J141041.25+531849.0) atz= 0.359 with 153 spectroscopic epochs of data representing a 10 yr baseline (2013–2023). We split the baseline into two regimes based on the 3× flux increase in the light curve: a “low state” phase during the years 2013–2019 and a “high state” phase during the years 2022–2023. The velocity-resolved lag profiles (VRLPs) indicate that gas with different kinematics dominates the line emission in different states. The HβVRLP begins with a signature of inflow onto the broad-line region (BLR) in the low state, while in the high state it is flatter with less signature of inflow. The HαVRLP begins consistent with a virialized BLR in the low state, while in the high state shows a signature of inflow. The differences in the kinematics between the Balmer lines and between the low state and the high state suggests complex BLR dynamics. We find that the BLR radius and velocity (both FWHM andσ) do not obey a constant virial product throughout the monitoring period. We find that the BLR lags and continuum luminosity are correlated, consistent with rapid response of the BLR gas to the illuminating continuum. The BLR kinematic profile changes in unpredictable ways that are not related to continuum changes and reverberation lag. Our observations indicate that nonvirial kinematics can significantly contribute to observed line profiles, suggesting caution for black hole mass estimation in luminous and highly varying quasars like RM160.