| Name: Rachana . |
| Affiliation: Indian Institute of Science |
| Conference ID: ASI2026_592 |
| Title: Continuum and Emission-Line Variability in NLSy1 Galaxies Using SDSS and DESI |
| Abstract Type: Poster |
| Abstract Category: Galaxies and Cosmology |
| Author(s) and Co-Author(s) with Affiliation: Rachana(Indian Institute of Science, Bangalore - 560012, India), Vivek M.(Indian Institute of Astrophysics, Bangalore - 560034, India), Arihant Tiwari(Indian Institute of Astrophysics, Bangalore - 560034, India), Suvendu Rakshit(Aryabhatta Research Institute of Observational Science, Nanital-263001, India) |
| Abstract: Narrow-line Seyfert 1 galaxies (NLSy1s) represent an extreme class of active galactic nuclei (AGN), often characterized by strong optical Fe II emission, relatively narrow broad Balmer lines, and high inferred Eddington ratios. Despite decades of study, estimating AGN properties and understanding their evolution in NLSy1s remains challenging. Multi-epoch spectroscopy offers a direct way to quantify intrinsic spectral changes and relate them to the physical state of the accretion flow.
In this work, we investigate spectral variability in a large sample of 7,728 NLSy1s curated by combining the NLSy1 catalog with SDSS and DESI DR1 spectroscopy. The availability of repeated DESI observations enables a systematic multi-epoch study of continuum and line evolution. Our primary focus is on continuum variability, as traced through changes in the optical continuum spectral slope, which provides a sensitive diagnostic of continuum shape evolution and potential fluctuations in the accretion state.
Using consistent spectral modeling of the SDSS and DESI spectra with PyQSOFit, we measure two-epoch changes in the optical continuum slope and in key line diagnostics, including Fe II and Balmer-line properties. We will discuss the distribution of these spectral changes across the sample and their connection to basic AGN parameters such as black hole mass and Eddington ratio. |
