Identifying the 3FHL catalog: I. Results of the KOSMOS optical spectroscopy campaign

TL;DR

This study conducted optical spectroscopy on 28 unclassified blazars from the 3FHL catalog, classifying most as BL Lacs, determining redshifts for some, and contributing to understanding blazar emission and extragalactic background light.

Contribution

First optical spectroscopic follow-up of 3FHL blazars, providing classifications and redshift estimates to enhance blazar population studies.

Findings

27 blazars classified as BL Lacs

Redshift determined for 3 objects, z>0.836 for the farthest

Established a foundation for a complete high-energy blazar sample

Abstract

We present the results of the optical spectroscopy follow-up of a sample of 28 unclassified blazars from the Third Fermi-LAT Catalog of High-Energy Sources (3FHL). All the spectra were taken with the 4m Mayall telescope at Kitt Peak. With this follow-up program we are able to classify 27 out of 28 objects as BL Lacs, while the remaining one is a flat spectrum radio quasar. We determine a redshift (z) for three of these objects and a lower limit on z for other four sources: the farthest object for which we obtain a redshift has z>0.836. These results are part of a more extended campaign of optical spectroscopy follow-up of 3FHL blazars, aimed to obtain a complete sample of blazars at >10 GeV which will then be used to extend our knowledge on blazar emission mechanisms and on the extragalactic background light.