Spectral comparison between AGN at z = 0.1, 0.2 and 0.3

TL;DR

This study compares the spectral properties of AGN at three different redshifts to investigate potential evolutionary trends, using a large sample from ROSAT and SDSS data.

Contribution

It provides a spectral comparison across redshifts 0.1, 0.2, and 0.3, accounting for selection biases to assess AGN evolution.

Findings

No significant evolution detected in AGN spectral sub-types with redshift.

Selection biases carefully considered to ensure robust conclusions.

Sample includes 812 sources with detailed spectral classification.

Abstract

We identified three samples of ROSAT sources with Sloan Digital Sky Survey spectra, one at redshift z = 0.1, a second one at z = 0.2 and a third one at z = 0.3. 812 sources in total were examined. We determined the nature and spectral sub-types of the sources by visual inspection. The fraction of each sub-type at each of the three redshifts are then calculated. We consider selection biases caused by the luminosity cut-off threshold to determine whether any systematic trends in AGN type are evident with increasing redshift. We hence probe if an evolution effect is detected in our sample.