Radio and gamma-ray emission in faint BL Lacs

TL;DR

This study investigates the radio and gamma-ray properties of a new, homogeneous sample of 42 faint BL Lac objects using multiwavelength data, including VLBA and Fermi observations, to better understand their emission mechanisms.

Contribution

First systematic multiwavelength analysis of faint BL Lacs selected without flux constraints, providing new insights into their parsec-scale structure and gamma-ray emission.

Findings

Faint BL Lacs show diverse radio structures.

Gamma-ray emission detected in a subset of the sample.

Preliminary results suggest correlations between radio and gamma-ray properties.

Abstract

The advent of Fermi is changing our understanding on the radio and gamma-ray emission in Active Galactic Nuclei. In fact, contrary to previous campaigns, Fermi mission reveals that BL Lac objects are the most abundant emitters in gamma-ray band. However, since they are relatively weak sources, most of their parsec scale structure as their multifrequency properties are poorly understood and/or not systematically investigated. Our main goal is to analyse, using a multiwavelength approach, the nuclear properties of an homogeneous sample of 42 faint BL Lacs, selected, for the first time in literature, with no constraint on their radio and gamma-ray flux densities/emission. We began asking and obtaining new VLBA observations at 8 and 15 GHz for the whole sample. We derived fundamental parameters as radio flux densities, spectral index information, and parsec scale structure. Moreover, we investigated their gamma-ray emission properties using the 2LAT Fermi results. Here, we report our preliminary results on the radio and gamma-ray properties of this sample of faint BL Lacs. In the next future, we will complete the multiwavelength analysis.