2021/02/08 by Subhashree Swain, P. Shalima, K. V. P. Latha +2 · 5 citations
Physics and Astronomy · #Accretion (finance) #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Galaxy #Geometry #Optics #Physics #RADIUS #Radiative transfer #Ring (chemistry) #Spectral energy distribution #Stellar, planetary, and galactic studies #Torus #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stab372
published in Monthly Notices of the Royal Astronomical Society 503(4), 5877-5893 (Oxford University Press) · 21 pages, 24 figures, accepted for publication in MNRAS
openalex publication_date 2021/02/08 · arxiv created 2021/02/09 · arxiv updated 2021/02/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
ABSTRACT We model the near-infrared (NIR) spectral energy distribution (SED) of NGC 4151 with a 3D radiative transfer skirt code, using which torus only (TO) and ring and torus (RAT) scenarios are studied. In the RAT models, a graphite ring-like structure (clumpy or smooth) is incorporated between the torus and the accretion disc. We vary the inclination angle (i), inner radius (of the torus and the ring, Rin,t and Rin,r, respectively), torus half-opening angle (σ), optical depth (τ 9.7, \rm t of the torus and τ 9.7, \rm r of the ring), and the dust clump size (Rclump). We perform a statistical analysis of the parameter space and find that all the models are able to explain the flat NIR SED of NGC 4151 with minor differences in the derived parameters. For the TO model, we get Rin,t = 0.1 pc, σ = 30°, i = 53°, τ 9.7, \rm t = 10, and the clumpsize, Rclump = 0.4 pc. For the smooth RAT model, R\rm in, \rm r = 0.04 pc and τ 9.7, \rm total = 11 and for the clumpy RAT model, Rin,r = 0.04 pc/0.06 pc and τ 9.7, \rm total = 20. The Rin,t from the TO model does not agree with the NIR observations (∼0.04 pc). Hence, the most likely scenario is that a hot graphite ring is located at a distance 0.04 pc from the centre, composed of a smooth/clumpy distribution of dust followed by a dusty torus at 0.1 pc with interstellar medium type of grains.