Spectral energy distributions and high-energy emission of BL Lac type objects

TL;DR

This study analyzes the spectral energy distributions of 201 BL Lac objects, revealing that high-energy detected sources are predominantly low-energy peaked, and explores their correlation with ultra-high-energy cosmic rays.

Contribution

It provides the first comprehensive analysis of optical-to-X-ray spectral indices for a large BL Lac sample, linking spectral properties to high-energy emission and cosmic ray correlations.

Findings

EGRET-detected BL Lacs are low-energy peaked.

Positional correlation with cosmic rays is dominated by low-energy-peaked BL Lacs.

High-energy emission is associated with low-energy peaked spectral types.

Abstract

Based on identifications from the Veron and Quasars.org catalogs, we determine the optical-to-X-ray spectral indices for a sample of 201 BL Lac type objects (BLLs) and search for trends in the distribution of these indices of the sources detected in high-energy bands. We find that EGRET-detected sources are low-energy peaked and that the positional correlation with the arrival directions of ultra-high-energy cosmic rays from the previously studied AGASA, Yakutsk and High Resolution Fly's Eye samples is dominated by low-energy-peaked BLLs.