Kukreti, Pranav and Morganti, Raffaella and Bondi, Marco and Oosterloo, Tom and Tadhunter, Clive and Morabito, Leah K. and Adams, E. A. K. and Adebahr, B. and de Blok, W. J. G. and de Gasperin, F. and Drabent, A. and Hess, K. M. and Ivashina, M. V. and Kutkin, A. and Mika, Á. M. and Oostrum, Leon and Shimwell, T. W. and van der Hulst, J. M. and van Leeuwen, Joeri and van Weeren, R. J. and Vohl, Dany and Ziemke, J. (2022) 'Seeing the forest and the trees: a radio investigation of the ULIRG Mrk 273.', Astronomy & Astrophysics, 664 . A25.
Galaxy mergers have been observed to trigger nuclear activity by feeding gas to the central supermassive black hole. One such class of objects are Ultra Luminous InfraRed Galaxies (ULIRGs), which are mostly late stage major mergers of gas-rich galaxies. Recently, large-scale (∼100 kpc) radio continuum emission has been detected in a select number of ULIRGs, all of which also harbour powerful Active Galactic Nuclei (AGN). This hints at the presence of large-scale radio emission being evidence for nuclear activity. Exploring the origin of this radio emission and its link to nuclear activity requires high sensitivity multi-frequency data. We present such an analysis of the ULIRG Mrk 273. Using the International LOFAR telescope (ILT), we detected spectacular large-scale arcs in this system. This detection includes, for the first time, a giant ∼190 kpc arc in the north. We propose these arcs are fuelled by a low power radio AGN triggered by the merger. We also identified a bright ∼45 kpc radio ridge, which is likely related to the ionised gas nebula in that region. We combined this with high sensitivity data from APERture Tile In Focus (Apertif) and archival data from the Very Large Array (VLA) to explore the spectral properties. The ILT simultaneously allowed us to probe the nucleus at a resolution of ∼0.3″, where we detected three components, and, for the first time, diffuse emission around these components. Combining this with archival high frequency VLA images of the nucleus allowed us to detect absorption in one component, and a steep spectrum radio AGN in another. We then extrapolate from this case study to the importance of investigating the presence of radio emission in more ULIRGs and what it can tell us about the link between mergers and the presence of radio activity.
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|Publisher Web site:||https://doi.org/10.1051/0004-6361/202243174|
|Publisher statement:||Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.|
|Date accepted:||04 May 2022|
|Date deposited:||19 August 2022|
|Date of first online publication:||03 August 2022|
|Date first made open access:||19 August 2022|
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