Optical Continuum Reverberation in the Dwarf Seyfert Nucleus of NGC 4395

August 2022 • 2022ApJ...934L..37M

Authors • Montano, John W. • Guo, Hengxiao • Barth, Aaron J. • U, Vivian • Remigio, Raymond • González-Buitrago, Diego H. • Hernández Santisteban, Juan V.

Abstract • In order to constrain the size of the optical continuum emission region in the dwarf Seyfert 1 galaxy NGC 4395 through reverberation mapping, we carried out high-cadence photometric monitoring in the griz filter bands on two consecutive nights in 2022 April using the four-channel MuSCAT3 camera on the Faulkes Telescope North at Haleakalā Observatory. Correlated variability across the griz bands is clearly detected, and the r-, i-, and z-band light curves show lags of ${7.72}_{-1.09}^{+1.01}$ , ${14.16}_{-1.25}^{+1.22}$ , and ${20.78}_{-2.09}^{+1.99}$ minutes with respect to the g band when measured using the full-duration light curves. When lags are measured for each night separately, the Night 2 data exhibit lower cross-correlation amplitudes and shorter lags than the Night 1 light curves. Using the full-duration lags, we find that the lag-wavelength relationship is consistent with the τ ∝ λ ^4/3 dependence found for more luminous active galactic nuclei. Combining our results with continuum lags measured for other objects, the lag between g and z band scales with optical continuum luminosity as τ _gz ∝ L ^0.56±0.05, similar to the scaling of broad-line region size with luminosity, reinforcing recent evidence that diffuse continuum emission from the broad-line region may contribute substantially to optical continuum variability and reverberation lags.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2022ApJ...934L..37M
• PDF https://iopscience.iop.org/article/10.3847/2041-8213/ac7e54/pdf
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/2022ApJ...934L..37M
• PREPRINT http://arxiv.org/abs/2205.13620
• ELECTR https://iopscience.iop.org/article/10.3847/2041-8213/ac7e54