| Name: Khundongbam Roshan Chenglei |
| Affiliation: Bangalore University |
| Conference ID: ASI2026_848 |
| Title: Investigation on the nature of UV Variability in Fairall 9 Seyfert 1 Active Galaxy |
| Abstract Type: Poster |
| Abstract Category: Galaxies and Cosmology |
| Author(s) and Co-Author(s) with Affiliation: Sudha D R(Bangalore University, Bengaluru-560056, India), Dr Vijayakumar H Doddamani(Bangalore University, Bengaluru-560056, India), Khundongbam Roshan Chenglei(Bangalore University, Bengaluru-560056, India), Vedavathi P(Bangalore University, Bengaluru-560056, India), Nalina B N(Bangalore University, Bengaluru-560056, India), Prathiba S(Bangalore University, Bengaluru-560056, India), Dr Basavaraj Sannakki(Gulbarga University, Gulbarga, Karnataka, India) |
| Abstract: Active Galactic Nuclei (AGNs) are characterized by strong variability across the electromagnetic spectrum, reflecting complex physical processes taking place in their central regions. In this study, we investigate the nature of the ultraviolet (UV) variability properties of the Seyfert 1 galaxy Fairall 9 using archival data from the International Ultraviolet Explorer (IUE). The analysis focuses on both continuum and prominent emission lines within the wavelength range 1000–3500 Å, covering a long-term monitoring period from 18 June 1978 to 26 December 1994 and an intensive short-term campaign from 28 April 1994 to 26 December 1994. The IUE data were processed using IRAF and IUE Tools to extract calibrated fluxes and derive parameters such as central wavelength, line flux, equivalent width, and full width at half maximum (FWHM) for major UV lines such as Lyα+NV, Si IV, and C IV. Continuum fluxes were measured in UV windows (1325–1375 Å, 1425–1475 Å, and 1800–1850 Å) and analyzed using python codes developed for calculating variability parameters Rmax and Fvar 3.268 ±0.009,2.833±0.008, 2.824±0.007 and 0.364±0.00016,0.326±0.00015,0.316±0.00009 in short-term campaign while 10.324±0.032,9.448±0.025,7.812 ±0.015 and 0.603±0.00012,0.569±0.00012,0.316±0.00009 during long-term monitoring. The results reveal significant variability in both continuum and emission line fluxes, with emission lines showing comparatively higher amplitude variations. The continuum fluxes at different UV windows exhibit strong correlations among themselves, indicating coherent variability. The mean UV spectral index value (α = −0.96 ± 0.32) implies mild steepening toward shorter wavelengths. These results are consistent with earlier studies on other Seyfert 1 galaxies such as NGC 4151, NGC 5548, and 3C 390.3, confirming that Fairall 9 too exhibit similar variability. This study contributes to a deeper understanding of the UV variability behavior and accretion dynamics in Seyfert 1 galaxies.
Key words: Seyfert 1 galaxy, UV fluxes, emission lines, variability, and active galaxies.
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