What are the megahertz peaked-spectrum sources?
Megahertz peaked-spectrum (MPS) sources have spectra that peak at frequencies below 1 GHz in the observer's frame and are believed to be radio-loud active galactic nuclei (AGN). We recently presented a new method to search for high-redshift AGN by identifying unusually compact MPS sources. In t...
| Main Authors: | , , , , , , , , , , |
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| Format: | Journal Article |
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Oxford University Press
2016
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| Online Access: | http://hdl.handle.net/20.500.11937/73798 |
| _version_ | 1848763101121347584 |
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| author | Coppejans, R. Cseh, D. van Velzen, S. Falcke, H. Intema, Hubertus Paragi, Z. Müller, C. Williams, W. Frey, S. Gurvits, L. Körding, E. |
| author_facet | Coppejans, R. Cseh, D. van Velzen, S. Falcke, H. Intema, Hubertus Paragi, Z. Müller, C. Williams, W. Frey, S. Gurvits, L. Körding, E. |
| author_sort | Coppejans, R. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Megahertz peaked-spectrum (MPS) sources have spectra that peak at frequencies below 1 GHz in the observer's frame and are believed to be radio-loud active galactic nuclei (AGN). We recently presented a new method to search for high-redshift AGN by identifying unusually compact MPS sources. In this paper, we present European VLBI Network (EVN) observations of 11 MPS sources which we use to determine their sizes and investigate the nature of the sources with ~10 mas resolution. Of the 11 sources, we detect 9 with the EVN. Combining the EVN observations with spectral and redshift information, we show that the detected sources are all AGN with linear sizes smaller than 1.1 kpc and are likely young. This shows that low-frequency colour-colour diagrams are an easy and efficient way of selecting small AGN and explains our high detection fraction (82 per cent) in comparison to comparable surveys. Finally we argue that the detected sources are all likely compact symmetric objects and that none of the sources are blazars. |
| first_indexed | 2025-11-14T10:58:06Z |
| format | Journal Article |
| id | curtin-20.500.11937-73798 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:58:06Z |
| publishDate | 2016 |
| publisher | Oxford University Press |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-737982019-03-13T01:07:48Z What are the megahertz peaked-spectrum sources? Coppejans, R. Cseh, D. van Velzen, S. Falcke, H. Intema, Hubertus Paragi, Z. Müller, C. Williams, W. Frey, S. Gurvits, L. Körding, E. Megahertz peaked-spectrum (MPS) sources have spectra that peak at frequencies below 1 GHz in the observer's frame and are believed to be radio-loud active galactic nuclei (AGN). We recently presented a new method to search for high-redshift AGN by identifying unusually compact MPS sources. In this paper, we present European VLBI Network (EVN) observations of 11 MPS sources which we use to determine their sizes and investigate the nature of the sources with ~10 mas resolution. Of the 11 sources, we detect 9 with the EVN. Combining the EVN observations with spectral and redshift information, we show that the detected sources are all AGN with linear sizes smaller than 1.1 kpc and are likely young. This shows that low-frequency colour-colour diagrams are an easy and efficient way of selecting small AGN and explains our high detection fraction (82 per cent) in comparison to comparable surveys. Finally we argue that the detected sources are all likely compact symmetric objects and that none of the sources are blazars. 2016 Journal Article http://hdl.handle.net/20.500.11937/73798 10.1093/mnras/stw799 Oxford University Press fulltext |
| spellingShingle | Coppejans, R. Cseh, D. van Velzen, S. Falcke, H. Intema, Hubertus Paragi, Z. Müller, C. Williams, W. Frey, S. Gurvits, L. Körding, E. What are the megahertz peaked-spectrum sources? |
| title | What are the megahertz peaked-spectrum sources? |
| title_full | What are the megahertz peaked-spectrum sources? |
| title_fullStr | What are the megahertz peaked-spectrum sources? |
| title_full_unstemmed | What are the megahertz peaked-spectrum sources? |
| title_short | What are the megahertz peaked-spectrum sources? |
| title_sort | what are the megahertz peaked-spectrum sources? |
| url | http://hdl.handle.net/20.500.11937/73798 |