上海科技大学知识管理系统

Observational studies of the innermost regions of the edge-on jets in nearby active galactic nuclei (AGN) are crucial to understanding their kinematics and morphology. For the inner jet of the nearby low-luminosity AGN in M84, we present new high-sensitivity observations with very long baseline Interferometry since 2019, as well as archival Very Long Baseline Array observations in 2014. We find that the compact core in M84 has an inverted-to-flat spectrum from 1.5-88 GHz. Based on the turnover frequency of 4.2 +/- 0.2 GHz in the spectrum, we estimated a magnetic field strength of 1 similar to 10 mG and an electron number density of similar to 10(5)cm(-3) in the core region. Three inner jet components within similar to 3 mas of the core are identified and traced in the images at 22 GHz, whose apparent speeds are 0.11 c, 0.27 c, and 0.32 c, respectively. We calculate the viewing angle of 58(-18)(+1)(7)degrees for the inner jet based on the proper motion and the flux ratio of jet to counterjet. A propagating sinusoidal model with a wavelength of similar to 3.4 mas is used to fit the helical morphology of the jet extended to 20 mas (similar to 2.2 x 10(4) Schwarzschild radii).