Discovery of a radio transient in M81
We report the discovery of a radio transient in the spiral galaxy M81. The transient was detected in early 2015 as part of a two-year survey of M81 made up of 12 epochs using the Karl G. Jansky Very Large Array. While undetected on 2014 September 12, the source was first detected on 2015 January 2,...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Journal Article |
| Language: | English |
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OXFORD UNIV PRESS
2019
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| Subjects: | |
| Online Access: | http://purl.org/au-research/grants/arc/FT140101082 http://hdl.handle.net/20.500.11937/90311 |
| _version_ | 1848765367393976320 |
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| author | Anderson, Gemma Miller-Jones, James Middleton, M.J. Soria, Roberto Swartz, D.A. Urquhart, Ryan Hurley-Walker, Natasha Hancock, Paul Fender, R.P. Gandhi, P. Markoff, S. Roberts, T.P. |
| author_facet | Anderson, Gemma Miller-Jones, James Middleton, M.J. Soria, Roberto Swartz, D.A. Urquhart, Ryan Hurley-Walker, Natasha Hancock, Paul Fender, R.P. Gandhi, P. Markoff, S. Roberts, T.P. |
| author_sort | Anderson, Gemma |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We report the discovery of a radio transient in the spiral galaxy M81. The transient was detected in early 2015 as part of a two-year survey of M81 made up of 12 epochs using the Karl G. Jansky Very Large Array. While undetected on 2014 September 12, the source was first detected on 2015 January 2, from which point it remained visible at an approximately constant luminosity of LR, ν = 1.5 ± 0.1 × 1024 erg s−1 Hz−1 at the observing frequency of 6 GHz for at least 2 months. Assuming this is a synchrotron event with a rise-time between 2.6 and 112 d, the peak luminosity (at equipartition) corresponds to a minimum energy of 1044 ≾ Emin ≾ 1046 erg and jet power of Pmin ∼ 1039 erg s−1, which are higher than most known X-ray binaries. Given its longevity, lack of short-term radio variability, and the absence of any multiwavelength counterpart (X-ray luminosity Lx ≾ 1036 erg s−1), it does not behave like known Galactic or extragalactic X-ray binaries. The M81 transient radio properties more closely resemble the unidentified radio transient 43.78+59.3 discovered in M82, which has been suggested to be a radio nebula associated with an accreting source similar to SS 433. One possibility is that both the new M81 transient and the M82 transient may be the birth of a short-lived radio bubble associated with a discrete accretion event similar to those observed from the ULX Holmberg II X-1. However, it is not possible to rule out other identifications including long-term supernova shockwave interactions with the surrounding medium from a faint supernova or a background active galaxy. |
| first_indexed | 2025-11-14T11:34:07Z |
| format | Journal Article |
| id | curtin-20.500.11937-90311 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:34:07Z |
| publishDate | 2019 |
| publisher | OXFORD UNIV PRESS |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-903112023-02-10T00:21:02Z Discovery of a radio transient in M81 Anderson, Gemma Miller-Jones, James Middleton, M.J. Soria, Roberto Swartz, D.A. Urquhart, Ryan Hurley-Walker, Natasha Hancock, Paul Fender, R.P. Gandhi, P. Markoff, S. Roberts, T.P. Science & Technology Physical Sciences Astronomy & Astrophysics stars: black holes supernovae: general galaxies: individual: M81 radio continuum: general radio continuum: transients X-rays: binaries MASS BLACK-HOLE X-RAY TRANSIENT SUPERNOVA-REMNANTS STAR-FORMATION GIANT FLARE V404 CYGNI SKY SURVEY H-ALPHA EMISSION OUTBURST We report the discovery of a radio transient in the spiral galaxy M81. The transient was detected in early 2015 as part of a two-year survey of M81 made up of 12 epochs using the Karl G. Jansky Very Large Array. While undetected on 2014 September 12, the source was first detected on 2015 January 2, from which point it remained visible at an approximately constant luminosity of LR, ν = 1.5 ± 0.1 × 1024 erg s−1 Hz−1 at the observing frequency of 6 GHz for at least 2 months. Assuming this is a synchrotron event with a rise-time between 2.6 and 112 d, the peak luminosity (at equipartition) corresponds to a minimum energy of 1044 ≾ Emin ≾ 1046 erg and jet power of Pmin ∼ 1039 erg s−1, which are higher than most known X-ray binaries. Given its longevity, lack of short-term radio variability, and the absence of any multiwavelength counterpart (X-ray luminosity Lx ≾ 1036 erg s−1), it does not behave like known Galactic or extragalactic X-ray binaries. The M81 transient radio properties more closely resemble the unidentified radio transient 43.78+59.3 discovered in M82, which has been suggested to be a radio nebula associated with an accreting source similar to SS 433. One possibility is that both the new M81 transient and the M82 transient may be the birth of a short-lived radio bubble associated with a discrete accretion event similar to those observed from the ULX Holmberg II X-1. However, it is not possible to rule out other identifications including long-term supernova shockwave interactions with the surrounding medium from a faint supernova or a background active galaxy. 2019 Journal Article http://hdl.handle.net/20.500.11937/90311 10.1093/mnras/stz1303 English http://purl.org/au-research/grants/arc/FT140101082 http://purl.org/au-research/grants/arc/DE180100346 OXFORD UNIV PRESS fulltext |
| spellingShingle | Science & Technology Physical Sciences Astronomy & Astrophysics stars: black holes supernovae: general galaxies: individual: M81 radio continuum: general radio continuum: transients X-rays: binaries MASS BLACK-HOLE X-RAY TRANSIENT SUPERNOVA-REMNANTS STAR-FORMATION GIANT FLARE V404 CYGNI SKY SURVEY H-ALPHA EMISSION OUTBURST Anderson, Gemma Miller-Jones, James Middleton, M.J. Soria, Roberto Swartz, D.A. Urquhart, Ryan Hurley-Walker, Natasha Hancock, Paul Fender, R.P. Gandhi, P. Markoff, S. Roberts, T.P. Discovery of a radio transient in M81 |
| title | Discovery of a radio transient in M81 |
| title_full | Discovery of a radio transient in M81 |
| title_fullStr | Discovery of a radio transient in M81 |
| title_full_unstemmed | Discovery of a radio transient in M81 |
| title_short | Discovery of a radio transient in M81 |
| title_sort | discovery of a radio transient in m81 |
| topic | Science & Technology Physical Sciences Astronomy & Astrophysics stars: black holes supernovae: general galaxies: individual: M81 radio continuum: general radio continuum: transients X-rays: binaries MASS BLACK-HOLE X-RAY TRANSIENT SUPERNOVA-REMNANTS STAR-FORMATION GIANT FLARE V404 CYGNI SKY SURVEY H-ALPHA EMISSION OUTBURST |
| url | http://purl.org/au-research/grants/arc/FT140101082 http://purl.org/au-research/grants/arc/FT140101082 http://hdl.handle.net/20.500.11937/90311 |