The discovery of high power - high synchrotron peak blazars

TL;DR

This paper reports the discovery of high-power blazars with unprecedented high synchrotron peak frequencies, challenging existing models and providing new insights into blazar physics and gamma-ray absorption.

Contribution

It presents the first identification of high-power blazars with high synchrotron peaks, expanding the known blazar population and implications for the blazar sequence.

Findings

Four blazars have synchrotron peaks between 3x10^15 and 10^16 Hz.

Two sources are detected in the 10-100 GeV gamma-ray band.

These blazars are likely high-redshift flat-spectrum radio quasars.

Abstract

We study the quasi-simultaneous near-IR, optical, UV, and X-ray photometry of eleven gamma-ray selected blazars for which redshift estimates larger than 1.2 have been recently provided. Four of these objects turn out to be high-power blazars with the peak of their synchrotron emission between ~ 3 x 10^15 and ~ 10^16 Hz, and therefore of a kind predicted to exist but never seen before. This discovery has important implications for our understanding of physical processes in blazars, including the so-called "blazar sequence", and might also help constraining the extragalactic background light through gamma-ray absorption since two sources are strongly detected even in the 10 - 100 GeV Fermi-LAT band. Based on our previous work and their high powers, these sources are very likely high-redshift flat-spectrum radio quasars with their emission lines swamped by the non-thermal continuum.