Discrete Knot Ejection from the Jet in a Nearby Low Luminosity Active Galactic Nucleus, M81*

Abstract

Observational constraints of relativistic jets from black holes has largely come from the most powerful and extended jets\cite{Jorstad05,Asada14}, leaving the nature of the low luminosity jets a mystery\cite{Falcke04}. M81* is one of the nearest low-luminosity jets, which underwent an extremely large radio flare in 2011, allowing us to study compact core emission with unprecedented sensitivity and linear resolution. Utilizing a multi-wavelength campaign, we were able to track the flare as it re-brightened and became optically thick. Simultaneous X-ray observations indicated the radio re-brightening was preceded by a low energy X-ray flare at least $t_{\mathrm{delay}}>12\mathrm{days}$ prior. Associating the time delay between the two bands as the cooling time in a synchrotron flare\cite{Urry97,Bai03}, we find the magnetic field strength was $1.9<B<9.2\mathrm{G}$, which is consistent with magnetic field estimate from spectral-energy distribution modeling\cite{Kellerman81}, $B<10.2\mathrm{G}$. In addition, VLBA observations at 23 GHz clearly illustrate a discrete knot moving mildly relativistically at $v_{\mathrm{app}}/c=0.51\pm 0.17$ associated with the initial radio flare. The observations indicate radial jet motions for the first time in M81*. This has profound implications for jet production, as it means radial motion can be observed in even the lowest-luminosity AGN, but at slower velocities and smaller radial extents ($\approx 10^4{R}_{\mathrm{G}}$).

38 pages, 7 figures, published in Nature Physics

References in corpus (4)

• Measuring the kinetic power of AGN in the radio mode
• Results from an extensive simultaneous broadband campaign on the underluminous active nucleus M81*: further evidence for mass-scaling accretion in black holes
• SN 1993J VLBI (IV): A Geometric Determination of the Distance to M81 with the Expanding Shock Front Method
• Improved AGN light curve analysis with the z-transformed discrete correlation function

Cited by in corpus (7)

• Disk, Corona, Jet Connection in the Intermediate State of MAXI J1820+070 Revealed by NICER Spectral-Timing Analysis
• Delayed Radio Flares from a Tidal Disruption Event
• A "coronal-mass-ejection'' model for flares in Sagittarius A*
• Chandra Imaging of the Outer Accretion Flow onto the Black Hole at the Center of the Perseus Cluster
• The X-ray variation of M81* resolved by Chandra and NuSTAR
• A (likely) X-ray jet from NGC6217 observed by XMM-Newton
• An Energetic Hot Wind from the Low-luminosity Active Galactic Nucleus M81*