J1110+4817 -- a compact symmetric object candidate revisited

TL;DR

This paper revisits the classification of the quasar J1110+4817, using multi-frequency VLBI and Gaia data, suggesting it is likely a compact symmetric object (CSO) with unique extended features, aiding understanding of AGN evolution.

Contribution

It provides a comprehensive multi-frequency VLBI analysis of J1110+4817, clarifying its nature as a probable CSO with distinctive radio features, enhancing knowledge of early AGN stages.

Findings

J1110+4817 is likely a CSO based on VLBI and Gaia data.

Extended radio features nearly perpendicular to the main axis were observed.

The source's structure may involve a binary AGN, but a CSO classification is favored.

Abstract

Compact symmetric objects (CSOs) are radio-emitting active galactic nuclei (AGNs) typically with a double-lobed radio structure confined to within 1 kpc. CSOs represent the earliest evolutionary phase of jetted AGNs. Some of them may eventually evolve into large-scale extended double sources, while others stall within the host galaxy and die out, depending on the longevity of nuclear activity, the jet power, and parameters of the surrounding galactic environment. Studying CSOs is a useful tool for understanding the evolution of the galaxies and the interactions between the jets and the medium of the host galaxy. Based on milliarcsec-resolution imaging observations using very long baseline interferometry (VLBI), it is not always straightforward to distinguish between a compact double-lobed or a core-jet structure. The quasar J1110+4817 was considered a CSO candidate in the literature earlier, but because of the lack of clear evidence, it could not be securely classified as a CSO. Here we present a comprehensive analysis of archival multi-frequency VLBI observations combined with accurate Gaia optical astrometric information. Lower-frequency VLBI images reveal an extended radio feature nearly perpendicular to the main structural axis of the source, apparently emanating from the brighter northern feature, that is rare among the known CSOs. While the presence of a binary AGN system cannot be fully excluded, the most plausible explanation is that J1110+4817 is a CSO.