Giant radio sources (GRSs) harbor the Universe’s largest structures generated by individual galaxies, with projected source sizes exceeding 700 kpc. These enigmatic objects have been mainly studied at radio frequencies, and their physical properties in the high-energy domain are poorly understood. Here we present the results of a multiwavelength study focused on NuSTAR J112829+5831.8 (J1128+5831), the only known GRS serendipitously detected with the Nuclear Spectroscopic Telescope Array. Being located in proximity to the famous interacting galaxy system, Arp 299, J1128+5831 has been serendipitously observed also by the Chandra X-ray Observatory, Hubble Space Telescope, and XMM-Newton satellites. From radio observations with the Low Frequency Array, the NRAO VLA Sky Survey, and the Very Large Array Sky Survey, we have determined that J1128+5831 has an overall steep radio spectrum (α = −0.86; Fν ∝ να) and a low core dominance (CD = −2.4, in log-scale), indicating the source to be viewed at large angles. From the X-ray spectral analysis, we found J1128+5831 to harbor an obscured active galactic nucleus (AGN) with neutral hydrogen column density exceeding 1023 cm−2. Its optical spectrum, taken with the Dark Energy Spectroscopic Instrument, exhibits prominent narrow emission lines but lacks broad components, thus confirming J1128+5831 to be a Type 2 AGN powered by a radiatively efficient accreting system. Overall, the broadband properties of J1128+5831 are consistent with those observed for the general GRS population.
A Serendipitous NuSTAR Detection of a Giant Radio Source Harboring an Obscured Active Galactic Nucleus
Creators
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1.
Inter-University Centre for Astronomy and Astrophysics
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2.
University of Bologna
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3.
Clemson University
- 4. INAF, Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, via P. Gobetti 93/3, 40129 Bologna, Italy
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5.
California Institute of Technology
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6.
Bielefeld University
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Assam Don Bosco University
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Ashoka University
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University of Birmingham
Abstract
Copyright and License
© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
We thank the journal referee for constructive criticism. This work has made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). This work is based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. The scientific results reported in this article are based on data obtained from the Chandra Data Archive. This research has made use of software provided by the Chandra X-ray Center (CXC) in the application packages CIAO, ChIPS, and Sherpa. This research made use of the crossmatch service provided by CDS, Strasbourg.
LOFAR data products were provided by the LOFAR Surveys Key Science project (LSKSP; https://lofar-surveys.org/) and were derived from observations with the International LOFAR Telescope (ILT). LOFAR is the Low Frequency Array designed and constructed by ASTRON. It has observing, data processing, and data storage facilities in several countries, which are owned by various parties (each with its own funding sources), and which are collectively operated by the ILT foundation under a joint scientific policy. The efforts of the LSKSP have benefited from funding from the European Research Council, NOVA, NWO, CNRS-INSU, the SURF Co-operative, the UK Science and Technology Funding Council, and the Jülich Supercomputing Centre.
We acknowledge the use of Hubble Advanced Products available at the Mikulski Archive for Space Telescopes. This research has made use of NASA’s Astrophysics Data System Bibliographic Services. This research has made use of data obtained through the High Energy Astrophysics Science Archive Research Center Online Service, provided by the NASA/Goddard Space Flight Center.
The HST data are available at MAST: doi:10.17909/avwb-jy09. This paper employs a list of Chandra datasets, obtained by the Chandra X-ray Observatory, contained in doi:10.25574/cdc.532.
Facilities
XMM - Newton X-Ray Multimirror Mission satellite, NuSTAR - The NuSTAR (Nuclear Spectroscopic Telescope Array) mission, CXO - Chandra X-ray Observatory satellite, HST - Hubble Space Telescope satellite.
Software References
CIAO (v.4.17), SAS (v.21.0.0), XSPEC (v 12.10.1; K. A. Arnaud 1996), Astropy (Astropy Collaboration et al. 2013, 2018).
Files
Paliya_2026_ApJ_999_83.pdf
Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2602.01647 (arXiv)
- Is supplemented by
- Dataset: 10.17909/avwb-jy09 (DOI)
- Dataset: 10.25574/cdc.532 (DOI)
Funding
- Jet Propulsion Laboratory
- National Aeronautics and Space Administration
Dates
- Submitted
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2025-10-31
- Accepted
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2026-02-01
- Available
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2026-02-25Published
Caltech Custom Metadata
- Caltech groups
- NuSTAR , Space Radiation Laboratory , Division of Physics, Mathematics and Astronomy (PMA)
- Publication Status
- Published