Probing the Jet Collimation Profile of M84

講演者：Elika Prameswari Fariyanto

How the jet in active galactic nuclei (AGN) is collimated has been a longstanding issue in astrophysics. Recent high-resolution VLBI analysis of an increasing number of AGN jet sources has greatly improved our observational understanding of jet collimation properties near the supermassive black hole. However, previous studies on jet collimation were exclusively based on bright and powerful jet sources. Here, we focus on the nearby radio galaxy M84, a prototypical source of low-luminosity AGN (LLAGN), enabling us to examine the jet collimation property at the lower end of the jet activity. We analyzed the detailed jet morphology of M84 using the Very Long Baseline Array and archival Very Large Array data, and found a transition from a semi-parabolic to a conical shape. The distance of the collimation break is significantly shorter than those typically seen in more powerful jets, suggesting that the collimation of the low-power jet is less efficient. In addition, we measure the frequency-dependent core shift effect using phase referencing observations and discuss the jet physical properties.