4C 49.22

Lore & Background

4C 49.22 was first discovered as an astronomical radio source in 1967. Its radio spectrum is flat, classifying it as a flat spectrum radio quasar. The host galaxy is an extremely large luminous elliptical galaxy with an off-centered nucleus and a slight elongation towards the north-east. A faint tidal arm is curved, suggesting an interaction with a small companion 10 arcseconds away. The central supermassive black hole is estimated to be 3.3 × 10^8 M☉.

The radio structure is compact, observed by the Very Long Baseline Array as a triple with a halo structure oriented north to south. A bright radio core has an estimated flux density of 338 mJy at 5 GHz and a flat spectrum between 1.6 and 15 GHz. The one-sided radio jet, studied by very-long-baseline interferometry, is slightly extended for about three milliarcseconds and contains a knot feature at around 1.39 ± 0.1 milliarcsecond from the core. On the southwest side, the jet intensity increases brightly until the knot position, where it fades away. The jet has a knotty appearance, with knot features having a jet power between 2.0 × 10^45 to 1.4 × 10^48 erg s⁻¹. High polarization is present, and the rotation measure increases from 15 rad m⁻² at the core to 25 rad m⁻² at the knot. The jet has also been studied in X-rays, where a hotspot feature is located in its southern lobe and further separated into two components.

Reader's Guide

4C 49.22 is significant as a blazar and flat spectrum radio quasar, demonstrating the extreme variability characteristic of such objects, including a gamma-ray flare observed on 15 May 2011 after a prolonged low-activity state. Its host galaxy, an extremely large luminous elliptical with an off-centered nucleus and tidal features, provides evidence of a past interaction with a small companion, offering insight into galaxy mergers and their role in fueling active galactic nuclei. The compact triple radio structure and the one-sided, knotty jet with high polarization and varying rotation measure make it a valuable target for studying relativistic jet physics, particle acceleration, and magnetic field structures. The jet power estimates and the X-ray hotspot further contribute to understanding energy transport in such systems. Its discovery in 1967 as a radio source and subsequent multi-wavelength studies underscore its importance in the study of blazars and radio-loud quasars.

Did You Know?

• 4C 49.22 displayed a gamma-ray flare on 15 May 2011 after a long period of low gamma-ray activity.
• The central supermassive black hole mass is estimated to be 3.3 × 10^8 M☉.
• The radio jet has a knot feature at about 1.39 ± 0.1 milliarcsecond from the core, with jet power between 2.0 × 10^45 and 1.4 × 10^48 erg s⁻¹.