Letter to the Editor

Radio jet precession in M 81*

¹ Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, Bonn 53121, Germany
e-mail: sfellenberg@mpifr-bonn.mpg.de
² Department of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University, PO Box 9010 6500 GL Nijmegen, The Netherlands
³ Department of Astronomy and Columbia Astrophysics Laboratory, Columbia University, 550 W 120th Street, New York, NY 10027, USA
⁴ Center for Computational Astrophysics, Flatiron Institute, 162 Fifth Avenue, New York, NY 10010, USA
⁵ Department of Theoretical physics and Astrophysics, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic

Received: 18 November 2022
Accepted: 28 February 2023

Abstract

We report four novel position angle measurements of the core region M 81* at 5 GHz and 8 GHz, which confirm the presence of sinusoidal jet precession in the M 81 jet region, as suggested by Martí-Vidal et al. (2011, A&A, 533, A111). The model makes three testable predictions regarding the evolution of the jet precession, which we test in our data with observations from 2017, 2018, and 2019. Our data confirm a precession period of ∼7 yr on top of a small linear drift. We further show that two 8 GHz observation are consistent with a precession period of ∼7 yr but show a different time lag with respect to the 5 GHz and 1.7 GHz observations. We do not find a periodic modulation of the light curve with the jet precession and therefore rule out a Doppler nature for the historic 1998–2002 flare. Our observations are consistent with either a binary black hole origin for the precession or the Lense-Thirring effect.