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Vijayakumar Honnappa Doddamani, Bryan Rithesh Miranda & Vedavathi Prabhakar

Nature of UV Variability in NGC 4151 from IUE’s Intensive Monitoring Spectroscopic Data

(Volume 93 - Année 2024 — No 2 - Proceeedings of the 3rd BINA Workshop on the Scientific Potential of the Indo-Belgian Cooperation)
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Abstract

The International Ultraviolet Explorer (IUE) satellite, launched in 1978 by NASA and ESA, has conducted highly successful long-term monitoring spectroscopic observations of many nearby (low-redshift) bright active galaxies, including NGC 1068, NGC 5548, NGC 7469, Fairall 9,MRK 335 and NGC 4151. Notably, IUE has monitored NGC 4151 more intensively than any other active galaxy, obtaining 414 spectra during its campaign from December 1 to 15, 1993. Here, we present results of our recent studies on the emission line and continuum variabilities characterised by the Rmax and Fvar parameters. From the analysis of the short timescale, intense monitoring data, we obtained Rmax values ranging between 2.14±0.02 and 1.62±0.01 corresponding to the UV continua 1270 Å, and 2705 Å, respectively. The corresponding Fvar values varied from 9.62±0.04% to 5.19±0.04 %. Furthermore, the Rmax values for the UV emission lines Lyα, C IV, He II, O III], C III] and Mg II have been found to be 4.09±0.06, 4.55±0.05, 13.65±0.68, 4.78±0.17, 2.76±0.02, respectively. The corresponding Fvar values obtained are 2.85±0.01 %, 26.51±0.06 %, 15.59±0.02 %, 48.93±1.79 %, 20.30±0.06% and 18.68±0.02 %, respectively. These results provide constraints on the amplitude of UV variability and the size of the broad-line region (BLR) in low luminosity Seyfert galaxies. The decreasing Fvar amplitudes of the UV continuum with respect to increasing wavelengths are significant results of the present study.

Keywords : NGC 4151, short-timescale variability, line and continuum fluxes, Rmax Parameter and Fvar amplitude

To cite this article

Vijayakumar Honnappa Doddamani, Bryan Rithesh Miranda & Vedavathi Prabhakar, «Nature of UV Variability in NGC 4151 from IUE’s Intensive Monitoring Spectroscopic Data», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 93 - Année 2024, No 2 - Proceeedings of the 3rd BINA Workshop on the Scientific Potential of the Indo-Belgian Cooperation, 811-819 URL : https://popups.uliege.be/0037-9565/index.php?id=11887.

About: Vijayakumar Honnappa Doddamani

Department of Physics, Bangalore University, Bengaluru-560056

About: Bryan Rithesh Miranda

Department of Physics, Christ Academy Institute for Advanced Studies, Bangalore 560083, India. Corresponding author: drvkdmani@gmail.com

About: Vedavathi Prabhakar

Department of Physics, Bangalore University, Bengaluru-560056