2025/11/12 by M. Probst, W. Kollatschny, Probst, M. A. +15
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.2511.09153
openalex publication_date 2025/11/12 · openalex created_date 2025/11/14 · openalex updated_date 2026/07/31
WPVS 48 is a nearby narrow-line Seyfert 1 galaxy without previous analysis of the broad-line region (BLR) by means of optical spectroscopic reverberation mapping. By studying the continuum and emission line variability of WPVS 48, we aim to infer the BLR size as well as the mass of the central supermassive black hole (SMBH). We analyse data from a dedicated optical spectroscopic reverberation mapping campaign of WPVS 48 taken with the 10 m Southern African Large Telescope (SALT) at 24 epochs over a period of 7 months between December 2013 and June 2014. WPVS 48 shows variability throughout the campaign. We find a stratified BLR, where the variability amplitude of the integrated emission lines decreases with distance to the ionizing continuum source. Specifically, the variable emission of Hα, Hβ, Hγ, He I λ5876 originates at distances of 16.0+4.0-2.0, 15.0+4.5-1.9, 12.5+3.5-2.5 and 14.0+2.5-2.1 light-days, respectively, to the optical continuum at 5100 A. The He II λ4686 lag is \lesssim 5 days. Based on the high S/N spectra, we identify variable emission of N III λ4640 and C IV λ4658 in the line complex with He II λ4686. We derive interband continuum delays increasing with wavelength up to ∼ 8 days. These delays are consistent with an additional diffuse continuum originating at the same distance as the variable Balmer emission. We derive a central black hole mass of (1.3-0.6+1.1)×107M\odot based on the integrated line-widths and distances of the BLR and discuss corrections for the inclination angle. This gives an Eddington ratio L/LEdd≈ 0.39 without correction for inclination.