J0011+3443: a GPS compact symmetric object, gravitational lens, or dual AGN?
Abstract
We present new multi-frequency VLBA observations of J0011+3443 (TXS 0008+344, z = 0.89) at 2.3, 4.9, 8.5, and, for the first time, 23.6 GHz. The source consists of two compact components A and B at a projected separation of 314 +/- 2 pc, plus a third feature C detected at 23.6 GHz at 0.6 mas from A. Archival low-resolution radio measurements confirm an integrated gigahertz-peaked spectrum, with an observed-frame peak frequency of 0.73 +/- 0.08 GHz and a peak flux density of 879 +/- 125 mJy. Comparison with nearly frequency-matched low-resolution measurements shows that the VLBA recovers 0.85 +/- 0.11 of the 4.85 GHz flux density and 0.50 +/- 0.06 of the 8.46 GHz flux density. The lower recovered fraction at 8.5 GHz suggests that low-surface-brightness emission is resolved out or falls below the VLBA surface-brightness sensitivity. We therefore interpret the VLBA component spectra as spectra of the compact recovered emission only. The 23.6 GHz morphology, the absence of a detected flat-spectrum core, the similar compact spectra of A and B, and the steep integrated GHz spectrum favor an interpretation of J0011+3443 as a GPS-class compact symmetric object, possibly in a short-lived or relic phase, although a dual-AGN origin cannot be excluded without multi-epoch astrometry.
Related
- Gravitational-Wave Microlensing as a Probe of Compact Object Population
- Identity Crisis: Untangling Mass-Ordering Artifacts from Compact-Object Pairing in Gravitational-Wave Populations
- MUSE spectroscopy of the compact dual AGN in the z=3.273 radio-loud gravitational lens MG B2016+112
- Hunting for Compact Object Binaries from eRASS1 Optical Counterparts through ZTF Time-domain Photometry and Multi-wavelength Surveys
- Hunting for Compact Object Binaries from eRASS1 Optical Counterparts through ZTF Time-domain Photometry and Multiwavelength Surveys
BibTeX
@misc{traianou2026j00113443,
title = {{J0011+3443: a GPS compact symmetric object, gravitational lens, or dual AGN?}},
author = {Efthalia Traianou and Tingting Liu and Roman Gold and Richard Mushotzky},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.19928},
eprint = {2608.19928},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.19928},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - J0011+3443: a GPS compact symmetric object, gravitational lens, or dual AGN?
AU - Efthalia Traianou
AU - Tingting Liu
AU - Roman Gold
AU - Richard Mushotzky
PY - 2026
DA - 2026/09/25
PB - arXiv
DO - 10.48550/arxiv.2608.19928
UR - https://arxiv.org/abs/2608.19928
AB - We present new multi-frequency VLBA observations of J0011+3443 (TXS 0008+344, z = 0.89) at 2.3, 4.9, 8.5, and, for the first time, 23.6 GHz. The source consists of two compact components A and B at a projected separation of 314 +/- 2 pc, plus a third feature C detected at 23.6 GHz at 0.6 mas from A. Archival low-resolution radio measurements confirm an integrated gigahertz-peaked spectrum, with an observed-frame peak frequency of 0.73 +/- 0.08 GHz and a peak flux density of 879 +/- 125 mJy. Comparison with nearly frequency-matched low-resolution measurements shows that the VLBA recovers 0.85 +/- 0.11 of the 4.85 GHz flux density and 0.50 +/- 0.06 of the 8.46 GHz flux density. The lower recovered fraction at 8.5 GHz suggests that low-surface-brightness emission is resolved out or falls below the VLBA surface-brightness sensitivity. We therefore interpret the VLBA component spectra as spectra of the compact recovered emission only. The 23.6 GHz morphology, the absence of a detected flat-spectrum core, the similar compact spectra of A and B, and the steep integrated GHz spectrum favor an interpretation of J0011+3443 as a GPS-class compact symmetric object, possibly in a short-lived or relic phase, although a dual-AGN origin cannot be excluded without multi-epoch astrometry.
ER -