VERITAS Observations of M 87 in 2011/2012

TL;DR

This paper reports on VERITAS observations of M 87 in 2011/2012, aiming to understand the TeV gamma-ray emission and its relation to the galaxy's core activity, building on previous multi-wavelength flare detections.

Contribution

It provides new observational data of M 87's TeV gamma-ray activity during 2011/2012, contributing to understanding the emission region and mechanisms in this radio galaxy.

Findings

Detection of TeV gamma-ray activity in 2011/2012

No consistent pattern linking TeV flares to other wavelengths

Enhanced understanding of M 87's high-energy emission behavior

Abstract

The giant radio galaxy M 87 is located at a distance of 16.7 Mpc and harbors a super-massive black hole (6 billion solar masses) in its center. M 87 is one of just three radio galaxies known to emit TeV gamma-rays. The structure of its relativistic plasma jet, which is not pointing towards our line of sight, is spatially resolved in X-ray (Chandra), optical and radio (VLA/VLBA) observations. The mechanism and location of the TeV emitting region is one of the least understood aspects of AGN. In spring 2008 and 2010, the three TeV observatories VERITAS, MAGIC and H.E.S.S. detected two major TeV flares in coordinated observations. Simultaneous high-resolution observations at other wavelengths - radio (2008) and X-rays (2008/2010) - gave evidence that one of the TeV flares was related to an event in the core region; however, no common/repeated patterns could be identified so far. VERITAS continued to monitor M 87 in 2011/2012. The results of these observations are presented.