Spectral variability of radio sources at low frequencies
Spectral variability of radio sources encodes information about the conditions of intervening media, source structure, and emission processes. With new low-frequency radio interferometers observing over wide fractional bandwidths, studies of spectral variability for a large population of extragalact...
| Main Authors: | , , , , , , , , , |
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| Format: | Journal Article |
| Language: | English |
| Published: |
OXFORD UNIV PRESS
2021
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| Subjects: | |
| Online Access: | http://purl.org/au-research/grants/arc/FT190100231 http://hdl.handle.net/20.500.11937/91779 |
| _version_ | 1848765590007709696 |
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| author | Ross, Kat Callingham, J.R. Hurley-Walker, Natasha Seymour, Nick Hancock, Paul Franzen, Thomas Morgan, John White, S.V. Bell, M.E. Patil, P. |
| author_facet | Ross, Kat Callingham, J.R. Hurley-Walker, Natasha Seymour, Nick Hancock, Paul Franzen, Thomas Morgan, John White, S.V. Bell, M.E. Patil, P. |
| author_sort | Ross, Kat |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Spectral variability of radio sources encodes information about the conditions of intervening media, source structure, and emission processes. With new low-frequency radio interferometers observing over wide fractional bandwidths, studies of spectral variability for a large population of extragalactic radio sources are now possible. Using two epochs of observations from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey that were taken one year apart, we search for spectral variability across 100-230 MHz for 21 558 sources. We present methodologies for detecting variability in the spectrum between epochs and for classifying the type of variability: either as a change in spectral shape or as a uniform change in flux density across the bandwidth. We identify 323 sources with significant spectral variability over a year-long time-scale. Of the 323 variable sources, we classify 51 of these as showing a significant change in spectral shape. Variability is more prevalent in peaked-spectrum sources, analogous to gigahertz-peaked spectrum and compact steep-spectrum sources, compared to typical radio galaxies. We discuss the viability of several potential explanations of the observed spectral variability, such as interstellar scintillation and jet evolution. Our results suggest that the radio sky in the megahertz regime is more dynamic than previously suggested. |
| first_indexed | 2025-11-14T11:37:40Z |
| format | Journal Article |
| id | curtin-20.500.11937-91779 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:37:40Z |
| publishDate | 2021 |
| publisher | OXFORD UNIV PRESS |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-917792023-05-16T02:44:01Z Spectral variability of radio sources at low frequencies Ross, Kat Callingham, J.R. Hurley-Walker, Natasha Seymour, Nick Hancock, Paul Franzen, Thomas Morgan, John White, S.V. Bell, M.E. Patil, P. Science & Technology Physical Sciences Astronomy & Astrophysics galaxies: active radio continuum: galaxies radio continuum: general ACTIVE GALACTIC NUCLEI MOLONGLO REFERENCE CATALOG COMPACT SYMMETRIC OBJECT FREE-FREE ABSORPTION STEEP-SPECTRUM DATA RELEASE ARRAY SCINTILLATION SELECTION JETS astro-ph.GA astro-ph.GA Spectral variability of radio sources encodes information about the conditions of intervening media, source structure, and emission processes. With new low-frequency radio interferometers observing over wide fractional bandwidths, studies of spectral variability for a large population of extragalactic radio sources are now possible. Using two epochs of observations from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey that were taken one year apart, we search for spectral variability across 100-230 MHz for 21 558 sources. We present methodologies for detecting variability in the spectrum between epochs and for classifying the type of variability: either as a change in spectral shape or as a uniform change in flux density across the bandwidth. We identify 323 sources with significant spectral variability over a year-long time-scale. Of the 323 variable sources, we classify 51 of these as showing a significant change in spectral shape. Variability is more prevalent in peaked-spectrum sources, analogous to gigahertz-peaked spectrum and compact steep-spectrum sources, compared to typical radio galaxies. We discuss the viability of several potential explanations of the observed spectral variability, such as interstellar scintillation and jet evolution. Our results suggest that the radio sky in the megahertz regime is more dynamic than previously suggested. 2021 Journal Article http://hdl.handle.net/20.500.11937/91779 10.1093/mnras/staa3795 English http://purl.org/au-research/grants/arc/FT190100231 OXFORD UNIV PRESS fulltext |
| spellingShingle | Science & Technology Physical Sciences Astronomy & Astrophysics galaxies: active radio continuum: galaxies radio continuum: general ACTIVE GALACTIC NUCLEI MOLONGLO REFERENCE CATALOG COMPACT SYMMETRIC OBJECT FREE-FREE ABSORPTION STEEP-SPECTRUM DATA RELEASE ARRAY SCINTILLATION SELECTION JETS astro-ph.GA astro-ph.GA Ross, Kat Callingham, J.R. Hurley-Walker, Natasha Seymour, Nick Hancock, Paul Franzen, Thomas Morgan, John White, S.V. Bell, M.E. Patil, P. Spectral variability of radio sources at low frequencies |
| title | Spectral variability of radio sources at low frequencies |
| title_full | Spectral variability of radio sources at low frequencies |
| title_fullStr | Spectral variability of radio sources at low frequencies |
| title_full_unstemmed | Spectral variability of radio sources at low frequencies |
| title_short | Spectral variability of radio sources at low frequencies |
| title_sort | spectral variability of radio sources at low frequencies |
| topic | Science & Technology Physical Sciences Astronomy & Astrophysics galaxies: active radio continuum: galaxies radio continuum: general ACTIVE GALACTIC NUCLEI MOLONGLO REFERENCE CATALOG COMPACT SYMMETRIC OBJECT FREE-FREE ABSORPTION STEEP-SPECTRUM DATA RELEASE ARRAY SCINTILLATION SELECTION JETS astro-ph.GA astro-ph.GA |
| url | http://purl.org/au-research/grants/arc/FT190100231 http://hdl.handle.net/20.500.11937/91779 |