Archival VLBA Observations of the Cygnus A Nuclear Radio Transient (Cyg A-2) Strengthen the Tidal Disruption Event Interpretation
We have analyzed archival Very Long Baseline Array (VLBA) data for Cygnus A between 2002 and 2013, to search for radio emission from the transient discovered in 2015 by Perley et al. approximately 0.″4 from the nucleus of Cygnus A (Cyg A-2). Perley et al. use Very Large Array and VLBA archival data...
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| Format: | Journal Article |
| Language: | English |
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IOP PUBLISHING LTD
2020
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| Online Access: | http://dx.doi.org/10.3847/2041-8213/abb60d http://hdl.handle.net/20.500.11937/90031 |
| _version_ | 1848765314806841344 |
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| author | Tingay, Steven Miller-Jones, James Lenc, E. |
| author_facet | Tingay, Steven Miller-Jones, James Lenc, E. |
| author_sort | Tingay, Steven |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We have analyzed archival Very Long Baseline Array (VLBA) data for Cygnus A between 2002 and 2013, to search for radio emission from the transient discovered in 2015 by Perley et al. approximately 0.″4 from the nucleus of Cygnus A (Cyg A-2). Perley et al. use Very Large Array and VLBA archival data (between 1989 and 1997) to show that the transient rises in flux density by a factor of at least 5 in less than approximately 20 yr. With the additional data presented here, we revise the rise time to between approximately 4 and 6 yr, based on a new detection of the source at 15.4 GHz from 2011 October. Our results strengthen the interpretation of Cyg A-2 as the result of a tidal disruption event (TDE), as we can identify the location of the compact object responsible for the TDE and can estimate the angular expansion speed of the resulting radio-emitting structures, equivalent to an apparent expansion speed of <0.9c. While our results are consistent with recent X-ray analyses, we can rule out a previously suggested date of early 2013 for the timing of the TDE. We favor a timing between early 2009 and late 2011. Applying the model of Nakar Piran, we suggest a TDE causing a mildly relativistic outflow with a (density-dependent) total energy >1049 erg. Due to the improved temporal coverage of our archival measurements, we find that it is unlikely that Cyg A-2 has previously been in a high luminosity radio state over the last 30 yr. |
| first_indexed | 2025-11-14T11:33:17Z |
| format | Journal Article |
| id | curtin-20.500.11937-90031 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:33:17Z |
| publishDate | 2020 |
| publisher | IOP PUBLISHING LTD |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-900312023-02-07T04:01:08Z Archival VLBA Observations of the Cygnus A Nuclear Radio Transient (Cyg A-2) Strengthen the Tidal Disruption Event Interpretation Tingay, Steven Miller-Jones, James Lenc, E. Science & Technology Physical Sciences Astronomy & Astrophysics Active galaxies Extragalactic radio sources Experimental techniques We have analyzed archival Very Long Baseline Array (VLBA) data for Cygnus A between 2002 and 2013, to search for radio emission from the transient discovered in 2015 by Perley et al. approximately 0.″4 from the nucleus of Cygnus A (Cyg A-2). Perley et al. use Very Large Array and VLBA archival data (between 1989 and 1997) to show that the transient rises in flux density by a factor of at least 5 in less than approximately 20 yr. With the additional data presented here, we revise the rise time to between approximately 4 and 6 yr, based on a new detection of the source at 15.4 GHz from 2011 October. Our results strengthen the interpretation of Cyg A-2 as the result of a tidal disruption event (TDE), as we can identify the location of the compact object responsible for the TDE and can estimate the angular expansion speed of the resulting radio-emitting structures, equivalent to an apparent expansion speed of <0.9c. While our results are consistent with recent X-ray analyses, we can rule out a previously suggested date of early 2013 for the timing of the TDE. We favor a timing between early 2009 and late 2011. Applying the model of Nakar Piran, we suggest a TDE causing a mildly relativistic outflow with a (density-dependent) total energy >1049 erg. Due to the improved temporal coverage of our archival measurements, we find that it is unlikely that Cyg A-2 has previously been in a high luminosity radio state over the last 30 yr. 2020 Journal Article http://hdl.handle.net/20.500.11937/90031 10.3847/2041-8213/abb60d English http://dx.doi.org/10.3847/2041-8213/abb60d http://purl.org/au-research/grants/arc/DP200102471 http://creativecommons.org/licenses/by/4.0 IOP PUBLISHING LTD fulltext |
| spellingShingle | Science & Technology Physical Sciences Astronomy & Astrophysics Active galaxies Extragalactic radio sources Experimental techniques Tingay, Steven Miller-Jones, James Lenc, E. Archival VLBA Observations of the Cygnus A Nuclear Radio Transient (Cyg A-2) Strengthen the Tidal Disruption Event Interpretation |
| title | Archival VLBA Observations of the Cygnus A Nuclear Radio Transient (Cyg A-2) Strengthen the Tidal Disruption Event Interpretation |
| title_full | Archival VLBA Observations of the Cygnus A Nuclear Radio Transient (Cyg A-2) Strengthen the Tidal Disruption Event Interpretation |
| title_fullStr | Archival VLBA Observations of the Cygnus A Nuclear Radio Transient (Cyg A-2) Strengthen the Tidal Disruption Event Interpretation |
| title_full_unstemmed | Archival VLBA Observations of the Cygnus A Nuclear Radio Transient (Cyg A-2) Strengthen the Tidal Disruption Event Interpretation |
| title_short | Archival VLBA Observations of the Cygnus A Nuclear Radio Transient (Cyg A-2) Strengthen the Tidal Disruption Event Interpretation |
| title_sort | archival vlba observations of the cygnus a nuclear radio transient (cyg a-2) strengthen the tidal disruption event interpretation |
| topic | Science & Technology Physical Sciences Astronomy & Astrophysics Active galaxies Extragalactic radio sources Experimental techniques |
| url | http://dx.doi.org/10.3847/2041-8213/abb60d http://dx.doi.org/10.3847/2041-8213/abb60d http://hdl.handle.net/20.500.11937/90031 |