The jet of the BL Lacertae object PKS 2201+044: MAD near-IR adaptive optics observations and comparison with optical, radio and X-ray data

TL;DR

This study presents multiwavelength observations of the jet in BL Lac object PKS 2201+044, revealing morphological similarities across radio, near-IR, and optical wavelengths, and suggesting its classification between FRI and FRII radio sources.

Contribution

First near-IR adaptive optics observations of PKS 2201+044's jet, combined with existing data, providing new insights into its morphology and spectral properties.

Findings

Jet morphology is similar across radio, near-IR, and optical wavelengths.

Main jet knot's spectrum is dominated by synchrotron radiation.

PKS 2201+044 likely belongs to an intermediate class between FRI and FRII.

Abstract

Relativistic jets are a common feature of radio loud active galactic nuclei. Multifrequency observations are a unique tool to constrain their physics. We report on a detailed study of the properties of the jet of the nearby BL Lac object PKS 2201+044, one of the rare cases where the jet is detected from radio to X-rays. We use new adaptive optics near-IR observations of the source, obtained with the ESO multi-conjugated adaptive optics demonstrator (MAD) at the Very Large Telescope. These observations acquired in Ground-Layer Adaptive Optics mode are combined with images previously achieved by HST, VLA and Chandra to perform a morphological and photometric study of the jet. We find a noticeable similarity in the morphology of the jet at radio, near-IR and optical wavelengths. We construct the spectral shape of the main knot of jet that appears dominated by synchrotron radiation. On the basis of the jet morphology and the weak lines spectrum we suggest that PKS 2201+044 belongs to the class of radio sources intermediate between FRIs and FRIIs.