Efficiency tests for estimating the gas and stellar population parameters in Type 2 objects

Abstract

We investigated the efficiency of estimating characteristics of stellar populations (SP) and Active Galactic Nuclei (AGN) emission using ULySS code. To analyse simultaneously AGN and SP components in the integrated spectrum of Type 2 active galaxies, we modelled the featureless continuum (FC) and emission lines, and we used PEGASE.HR stellar population models provided by ULySS. In order to validate the method, we simulated over 7000 integrated spectra of Seyfert 2 galaxies. Spectra were generated using different characteristics of the featureless AGN continuum, signal-to-noise ratio (SNR), spectral ranges, properties of emission lines and single stellar population (SSP) model whose initial mass function (IMF) and abundance pattern is similar to the solar neighbourhood. Simulated spectra were fitted with ULySS to evaluate the ability of the method to extract SP and AGN properties. We found that the analysis with ULySS can efficiently restore the characteristics of SP in spectra of Seyfert 2 AGNs, where signal-to-noise ratio is higher than 20, and where SP contributes with more than 10% to the total flux. Degeneracies between AGN and SP parameters increase with increasing the AGN continuum fraction, which points out the importance of simultaneous fitting of the FC and SP contributions.

28 pages, 8 figures, appears in Advances in Space Research (2014)

References in corpus (25)

• Parametric Recovery of Line-of-Sight Velocity Distributions from Absorption-Line Spectra of Galaxies via Penalized Likelihood
• Evolutionary Stellar Population Synthesis with MILES. Part I: The Base Models and a New Line Index System
• The SAURON project - V. Integral-field emission-line kinematics of 48 elliptical and lenticular galaxies
• The SAURON project - III. Integral-field absorption-line kinematics of 48 elliptical and lenticular galaxies
• ULySS: A Full Spectrum Fitting Package
• Evolutionary synthesis of galaxies at high spectral resolution with the code PEGASE-HR
• Active Galactic Nuclei in the Sloan Digital Sky Survey: I. Sample Selection
• Coude-feed stellar spectral library - atmospheric parameters
• Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting
• Age and metallicity gradients in early-type galaxies: A dwarf to giant sequence
• Stellar Population and Kinematic Profiles in Spiral Bulges & Disks: Population Synthesis of Integrated Spectra
• Spectral Decomposition of Broad-Line AGNs and Host Galaxies
• The flux ratio of the [OIII] 5007,4959 lines in AGN: Comparison with theoretical calculations
• A Study of the Direct-Fitting Method for Measurement of Galaxy Velocity Dispersions
• Kinematics and stellar populations of the dwarf elliptical galaxy IC 3653
• Spectral Synthesis of the Nuclear Region of Seyfert 2 and Radio Galaxies
• The Stellar Populations in the Central Parsecs of Galactic Bulges Central Stellar Populations
• The Evolution of Early-Type Galaxies in Distant Clusters I.: Surface Photometry and Structural Parameters for 53 Galaxies in the z=0.33 Cluster CL1358+62
• The frequency of nuclear star-formation in Seyfert 2 galaxies
• Testing spectral models for stellar populations with star clusters: I. Methodology
• Stellar populations in early-type Coma cluster galaxies - I. The data
• Stellar population and kinematics of NGC404
• 3D Spectroscopic Study of the Line Emitting Regions of Mrk 493
• A new inverse method for stellar population synthesis and error analysis
• The gas kinematics in Mrk 533 nucleus and circumnuclear region: a gaseous outflow

Cited by in corpus (4)

• A Possible ~20 yr Periodicity in Long-term Optical Photometric and Spectral Variations of the Nearby Radio-Quiet Active Galactic Nucleus Ark 120
• Impact of an AGN featureless continuum on estimation of stellar population properties
• AGN Broad Line Region variability in the context of Eigenvector 1: case of NGC 5548
• Taming the derivative: diagnostics of the continuum and H$\beta$ emission in a prototypical Population B active galaxy