The 3HSP catalogue of Extreme & High Synchrotron Peaked Blazars

TL;DR

The 3HSP catalogue significantly expands and improves the completeness of high synchrotron peaked blazars, providing a valuable resource for VHE gamma-ray and neutrino astronomy research.

Contribution

This paper introduces the 3HSP catalogue, the largest and most complete list of HSP blazars, enhancing previous catalogs for better statistical and observational studies.

Findings

3HSP contains 2013 sources, 88% with redshift estimates.

Cross-matching suggests HSPs are likely neutrino counterparts.

The catalogue improves completeness over previous HSP lists.

Abstract

High synchrotron peaked blazars (HSPs or HBLs) play a central role in very high energy (VHE) gamma-ray astronomy, and likely in neutrino astronomy. Currently, the largest compilation of HSP blazars, the 2WHSP sample, includes 1691 sources, but it is not complete neither in the radio nor in the X-ray band. In order to provide a more sizable and more accurate set of HSP blazars that is useful for future statistical studies and to plan for VHE/TeV observations, we present the largest sample of extreme and high synchrotron peaked (EHSP;HSP) blazars and blazar candidates: the 3HSP catalogue. The 3HSP catalogue includes 2013 sources, 88% of which with a redshift estimation, a much larger percentage than in any other list of HSP blazars. All new {\gamma}-ray detections are described in the First and Second Brazil ICRANet gamma-ray blazar catalogues (1BIGB & 2BIGB) also taking into account the 4FGL list of {\gamma}-ray sources published by the Fermi large area telescope (Fermi-LAT) team. Moreover, the cross-matching between the 2WHSP, 2FHL HSPs, and IceCube neutrinos position has suggested that HSPs are likely counterparts of neutrino events, which implies the 3HSP catalogue is useful also in that respect. The 3HSP catalogue features improved completeness compared to its predecessors, the 1WHSP and 2WHSP catalogues, and follows the track of their increasing relevance for VHE astronomy.