Multi-Frequency Study of Spectral Indices of BL Lacertae Objects and Flat Spectrum Radio Quasars

TL;DR

This study analyzes spectral data of blazars to explore their classification, spectral properties, and potential unified evolutionary scheme across different blazar subclasses.

Contribution

It provides a comprehensive statistical analysis of Fermi-detected blazars, revealing spectral relationships and proposing a unified evolutionary framework.

Findings

Significant anti-correlation between gamma-ray and X-ray spectral indices.

Similar spectral properties across FSRQs and BL Lacs suggest a unified scheme.

Different spectral shapes imply distinct emission mechanisms in X-ray and gamma-ray bands.

Abstract

We present statistical analyses of a large homogenous data sample of Fermi-detected blazars thoroughly studied in order to reassess the relationship between flat-spectrum radio quasars (FSRQs) and subclasses of BL Lacertae objects (BL Lacs) blazar populations. We discovered from the average values of gamma-ray and X-ray spectral indices that the sequence of distribution is indicative of the blazar orientation scheme. Analyses of FSRQs and BL Lacs data show difference in the shape of gamma-ray and X-ray indices: significant anti-correlation (r~ greater than - 0.79) exists between gamma-ray and X-ray spectral indices. The spectral energy distributions of the blazar subclasses show that FSRQs and BL Lacs have similar spectral properties which can be unified through an evolutionary sequence. Nevertheless, there is a significant difference between the shapes of X-ray and gamma-ray spectra of blazars suggesting that different mechanisms are responsible for spectral variations in the two energy bands. All these results suggest that there is a form of a unified scheme for all blazars.