H$\alpha$ Reverberation Mapping of the Intermediate-Mass Active Galactic Nucleus in NGC 4395

Abstract

We present the results of a high-cadence spectroscopic and imaging monitoring campaign of the active galactic nucleus (AGN) of NGC 4395. High signal-to-noise-ratio spectra were obtained at the Gemini-N 8 m telescope using the GMOS integral field spectrograph (IFS) on 2019 March 7, and at the Keck-I 10 m telescope using the Low-Resolution Imaging Spectrometer (LRIS) with slitmasks on 2019 March 3 and April 2. Photometric data were obtained with a number of 1 m-class telescopes during the same nights. The narrow-line region (NLR) is spatially resolved; therefore, its variable contributions to the slit spectra make the standard procedure of relative flux calibration impractical. We demonstrate that spatially-resolved data from the IFS can be effectively used to correct the slit-mask spectral light curves. While we obtained no reliable lag owing to the lack of strong variability pattern in the light curves, we constrain the broad line time lag to be less than 3 hr, consistent with the photometric lag of $\sim 80$ min reported by Woo et al. (2019). By exploiting the high-quality spectra, we measure the second moment of the broad component of the H$\alpha$ emission line to be $586\pm 19$ km s${}^{-1}$, superseding the lower value reported by Woo et al. (2019). Combining the revised line dispersion and the photometric time lag, we update the black hole mass as $(1.7\pm 0.3)\times 10^4$ M${}_{\odot }$.

Accepted for publication in ApJ (Aug. 16th, 2021). 13 pages, 11 figures

References in corpus (6)

• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• The evolution of massive black hole seeds
• The black hole mass - stellar velocity dispersion relation of narrow-line Seyfert 1 galaxies
• CALIFA, the Calar Alto Legacy Integral Field Area survey. II. First public data release
• Improved Dynamical Constraints on the Mass of the central Black Hole in NGC 404
• A 10,000-solar-mass black hole in the nucleus of a bulgeless dwarf galaxy

Cited by in corpus (10)

• The Science of the Einstein Telescope
• Estimating AGN Black Hole Masses via Continuum Reverberation Mapping in the Era of LSST
• Optical Continuum Reverberation in the Dwarf Seyfert Nucleus of NGC 4395
• Rates of Stellar Tidal Disruption Events around Intermediate-Mass Black Holes
• A new timescale-mass scaling for the optical variation of active galactic nuclei across the intermediate-mass to supermassive scales
• Constraining the Low-Mass End of the Black Hole Mass Function and the Active Fraction of the Intermediate-mass Black Holes
• Conditional Neural Process for non-parametric modeling of AGN light curve
• Optical Continuum Reverberation Mapping of a Candidate IMBH in a Nearby Seyfert 1 Galaxy
• Variability as a new discovery channel for Intermediate-Mass Black Holes in the Time Domain Era
• Formation of A Nuclear Star Cluster Through A Merger Event In The Low Surface Brightness Galaxy AGC 223218