Very Long Baseline Interferometry Search for Nuclear Radio Continuum Emission in the Barred Spiral Galaxy NGC 7479
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arXiv
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866914494282727424 |
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| author | Laine, Seppo Momjian, Emmanuel Järvelä, Emilia Krichbaum, Thomas P. Komossa, S. Fischer, Travis C. Pannuti, Thomas G. |
| author_facet | Laine, Seppo Momjian, Emmanuel Järvelä, Emilia Krichbaum, Thomas P. Komossa, S. Fischer, Travis C. Pannuti, Thomas G. |
| contents | We have obtained very high angular resolution (a few milliarcseconds or sub-parsec scale) Very Long Baseline Array (VLBA) and European Very Long Baseline Interferometry (VLBI) Network (EVN) radio continuum images of the nucleus in the barred spiral galaxy NGC 7479, to search for possible nuclear emission on parsec scales. The observations were taken using phase referencing. Previous Karl G. Jansky Very Large Array (VLA) and Multi-Element Radio Linked Interferometer Network (MERLIN) observations revealed a large jet-like structure, apparently emanating from the nucleus, and unresolved nuclear emission at 0.1 arcsecond (about 15 pc at the assumed distance of 32 Mpc) scale, respectively. Our sensitive new VLBA and EVN images resolve the previously unresolved nuclear source and reveal two distinct emission regions (VLBI components) that are separated by about 30 milliarcseconds. We also report an apparent change in separation of the two main emission regions over the ten years between EVN and VLBA observations, implying relativistic radio jet motion or changes in shock illumination of gas by a nuclear wind. We measure the spectral indices and brightness temperatures of the VLBI components, and discuss possible physical causes of the observed emission. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_18950 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Very Long Baseline Interferometry Search for Nuclear Radio Continuum Emission in the Barred Spiral Galaxy NGC 7479 Laine, Seppo Momjian, Emmanuel Järvelä, Emilia Krichbaum, Thomas P. Komossa, S. Fischer, Travis C. Pannuti, Thomas G. Astrophysics of Galaxies We have obtained very high angular resolution (a few milliarcseconds or sub-parsec scale) Very Long Baseline Array (VLBA) and European Very Long Baseline Interferometry (VLBI) Network (EVN) radio continuum images of the nucleus in the barred spiral galaxy NGC 7479, to search for possible nuclear emission on parsec scales. The observations were taken using phase referencing. Previous Karl G. Jansky Very Large Array (VLA) and Multi-Element Radio Linked Interferometer Network (MERLIN) observations revealed a large jet-like structure, apparently emanating from the nucleus, and unresolved nuclear emission at 0.1 arcsecond (about 15 pc at the assumed distance of 32 Mpc) scale, respectively. Our sensitive new VLBA and EVN images resolve the previously unresolved nuclear source and reveal two distinct emission regions (VLBI components) that are separated by about 30 milliarcseconds. We also report an apparent change in separation of the two main emission regions over the ten years between EVN and VLBA observations, implying relativistic radio jet motion or changes in shock illumination of gas by a nuclear wind. We measure the spectral indices and brightness temperatures of the VLBI components, and discuss possible physical causes of the observed emission. |
| title | Very Long Baseline Interferometry Search for Nuclear Radio Continuum Emission in the Barred Spiral Galaxy NGC 7479 |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2604.18950 |