The new surprising behaviour of the two "prototype" blazars PKS 2155-304 and 3C 279

TL;DR

This paper reports unexpected high-energy behaviors in two well-known blazars, PKS 2155-304 and 3C 279, revealing new insights into their structure and challenging previous assumptions about their emission properties.

Contribution

It presents the first observation of large Compton dominance and high gamma-ray luminosity in PKS 2155-304, and the detection of 3C 279 at VHE, challenging existing models of blazar emission.

Findings

PKS 2155-304 shows a cubic relation between X-ray and VHE fluxes.

3C 279 is the first FSRQ detected at VHE.

High luminosity in 3C 279 cannot be easily explained by previous models.

Abstract

Recent VHE observations have unveiled a surprising behaviour in two well-known blazars at opposite sides of the blazar sequence. PKS 2155-304 have shown for the first time in an HBL a large Compton dominance, high gamma-ray luminosities and a cubic relation between X-ray and VHE fluxes. 3C 279 is the first FSRQ detected at VHE. The high luminosity required to overcome the significant absorption caused by the BLR emission cannot be easily reconciled with the historical and quasi-simultaneous SED properties. Both cases shed a new light on the structure and ambient fields of blazars. Contrary to previous claims, it is also shown that 3C 279 --as any FSRQ-- cannot in general provide robust constraints on the EBL.