The Continuing Saga of the Explosive Event(s) in the M87 Jet: Is M87 a Blazar?

TL;DR

This paper reviews recent observations of the M87 jet, especially the HST-1 knot, comparing its behavior to blazar activity, and discusses whether M87 exhibits blazar-like properties at large distances from the core.

Contribution

It provides a comprehensive analysis of M87's jet activity, proposing that blazar-like phenomena occur far from the jet origin, challenging traditional models.

Findings

HST-1 experienced a 50-80 times flare in 2005

Superluminal radio features observed in M87

HST-1 likely source of 2005 TeV emission

Abstract

We review the recent data on the knot HST-1 in the M87 jet in the context of typical blazar behavior. In particular we discuss the wide-band flare of 2005 which peaked at a factor of 50 to 80 times the intensity observed in 2000; the superluminal radio features; and the arguments that support the hypothesis that HST-1 was the source of the excess TeV emission found by H.E.S.S. in 2005. To the extent that M87 can be classified as a blazar, perhaps observed at a somewhat larger angle to the line of sight compared to most blazars, all of these blazar properties originate at a distance greater than 100 pc from the nucleus, and thus cannot be associated with the location of the 'launching of the jet'.