Astronomers investigate jet kinematics of the blazar 4C+21.35 | 1/16/2019 | Staff
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A 22 GHz KaVA image of 4C +21.35. Credit: Lee et al., 2019.

Using very-long-baseline-interferometry (VLBI), an international team of astronomers has conducted a kinematic study of a jet of the blazar 4C+21.35. The research, presented in a paper published April 5 on the arXiv pre-print repository, sheds more light on the nature of this quasar and its jet.

Blazars - Quasars - Holes - Centers - Galaxies

Blazars are very compact quasars associated with supermassive black holes at the centers of active, giant elliptical galaxies. Based on their optical emission properties, astronomers divide blazars into two classes: flat-spectrum radio quasars (FSRQs) that feature prominent and broad optical emission lines, and BL Lacertae objects (BL Lacs), which do not.

In general, blazars belong to a larger group of active galaxies that host active galactic nuclei (AGN), and their characteristic features are relativistic jets pointed almost exactly toward the Earth. However, the detailed mechanisms of ejection and collimation of jets are still poorly understood, and more studies of this phenomenon are required to improve our knowledge on the subject.

Redshift - Blazar - PKS - Very-high-energy - VHE

At a redshift of 0.433, the blazar 4C+21.35, also known as PKS 1222+216, is a nearby very-high-energy (VHE) flat-spectrum radio quasar. Previous studies have revealed that the object exhibits super-luminal apparent jet motions with apparent speeds ranging from three to 25 times greater than the speed of light (c) at milliarcsecond scales. Observations of this source also detected three gamma-ray flares—two occured in 2010 and one in 2014.

A group of astronomers led by Taeseok Lee of Seoul National University, South Korea, decided to observe 4C+21.35 using the Korean VLBI Network (KVN) and VLBI Exploration of Radio Astrometry (VERA) array (KaVA). The aim of this observational campaign was to characterize in detail the kinematics of the blazar and to investigate the connection between kinematics and gamma-ray activity in this object.

Shows - Activity

"Since 4C+21.35 shows ongoing vigorous γ-ray activity...
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