Collimation of the Relativistic Jet in the Quasar 3C 273

Abstract

The collimation of relativistic jets launched from the vicinity of supermassive black holes (SMBHs) at the centers of active galactic nuclei (AGNs) is one of the key questions to understand the nature of AGN jets. However, little is known about the detailed jet structure for AGN like quasars since very high angular resolutions are required to resolve these objects. We present very long baseline interferometry (VLBI) observations of the archetypical quasar 3C 273 at 86 GHz, performed with the Global Millimeter VLBI Array, for the first time including the Atacama Large Millimeter/submillimeter Array. Our observations achieve a high angular resolution down to ∼60 μas, resolving the innermost part of the jet ever on scales of ∼105 Schwarzschild radii. Our observations, including close-in-time High Sensitivity Array observations of 3C 273 at 15, 22, and 43 GHz, suggest that the inner jet collimates parabolically, while the outer jet expands conically, similar to jets from other nearby low-luminosity AGNs. We discovered the jet collimation break around 107 Schwarzschild radii, providing the first compelling evidence for structural transition in a quasar jet. The location of the collimation break for 3C 273 is farther downstream from the sphere of gravitational influence (SGI) from the central SMBH. With the results for other AGN jets, our results show that the end of the collimation zone in AGN jets is governed not only by the SGI of the SMBH but also by the more diverse properties of the central nuclei.

Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary System

“…Kishore et al (2024) estimate that the size of the emitting region is 280 ± 130 au. Comparing this with the Schwarzschild radii of the two BHs in the model, 360 au and 3 au, respectively, we see that the emitting region must be located in the jet of the secondary BH, as jets widen considerably beyond the size of the BH of their origin (Gómez et al 2022;Okino et al 2022;Lu et al 2023).…”

Key Science Goals for the Next-Generation Event Horizon Telescope

“…VLBI studies of jets at ten times larger angular scales have provided the most precise determination of jet launch time (and the corresponding activity in the accretion flow), evidence for strong directional variation and precession of the jet, and circumstantial evidence for interactions and-presumablyinternal shocks between components moving at different speeds. This is also the region in r g in which the jets of M87 * and other AGN have been seen to switch from an initially parabolic to a later conical cross section (e.g., [149,[188][189][190][191]). With the ngEHT, we can directly test if this same collimation is occurring in BHXRB jets.…”

How to Turn Jets into Cylinders near Supermassive Black Holes in 3D General Relativistic Magnetohydrodynamic Simulations

“…Boccardi et al (2021) find that the jet in NGC 315 exhibits a parabolic shape and becomes conical well inside the Bondi radius; they discuss that the winds launched by a thick accretion disk might be responsible for this shape transition. High-resolution images of 3C 273 show that the jet exhibits a parabolic shape up to 10 7 r g before expanding conically well outside of the BH sphere of gravitational influence (Okino et al 2022), which they expect to be approximately of the same order of magnitude as r B . The jet in Cygnus A features a parabolic shape up to r ; 2.4 × 10 4 r g ; 0.05r B , beyond which it turns into a cylinder; this suggests different environmental conditions than M87 (Boccardi et al 2016).…”