| Abstract : | Accurate quantitative optical/UV spectral analysis of AGNs necessitates estimation of several key spectral parameters. Various efforts have endeavoured to tackle this challenge including global fitting over the entire IR-to-X-ray range, analysis of specific lines, model-based continuum and line fitting routines, etc.[1]
We have indigenously developed a Python-based code designed for the spectral analysis of AGNs. We have adopted the approach of the QSFit package[1], but have added components which are necessary for accurate fitting of AGN spectra. Our model comprises contributions from (1)the AGN power-law continuum, (2)higher order Balmer lines, (3)the Host Galaxy, from a comprehensive template atlas[2], (4)Iron line templates for AGNs[1], and (5)optical lines (Hα, Hβ, OIII, NII, and SII), including broad and narrow components. Each line is represented by a Gaussian profile, characterised by parameters like total line luminosity, FWHM, and velocity offset. Constraints are applied to ensure the physical validity and reliability of the fitting. These components are sequentially added to the model in the order indicated above, with optimisation of parameters at every stage.
We have compared the outcome of our fitted spectra for several publicly available datasets of galaxies and AGNs from the ESO science portal. The final fitted spectra can be further analysed to obtain line fluxes and flux ratios which may be used as an aid to classify AGNs[3] and study their systematics across variations in intrinsic luminosity, morphology, redshift etc.
References:
[1] Calderone et al., MNRAS Vol.472, pg.4051 (2017) and references therein.
[2] Bruzual and Charlot, MNRAS, Vol.344, pg.1000 (2003)
[3] Baldwin et al., Publ. Astron. Soc. Pacific, Vol.93, pg.5 (1981)
[4] Silva et al., Astrophys. J., Vol.509, pg.103 (1998)
[5] Polletta et al., ApJ, Vol.663, pg.81 (2007) |
