Wide-band spectral variability of peaked spectrum sources
Characterizing spectral variability of radio sources is a technique that offers the ability to determine the astrophysics of the intervening media, source structure, emission, and absorption processes. We present broadband (0.072-10 GHz) spectral variability of 15 peaked-spectrum (PS) sources with t...
| Main Authors: | , , , , , |
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| Format: | Journal Article |
| Language: | English |
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OXFORD UNIV PRESS
2022
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| Subjects: | |
| Online Access: | http://purl.org/au-research/grants/arc/FT190100231 http://hdl.handle.net/20.500.11937/91782 |
| _version_ | 1848765590841327616 |
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| author | Ross, Kat Hurley-Walker, Natasha Seymour, Nick Callingham, J.R. Galvin, Tim Johnston-Hollitt, Melanie |
| author_facet | Ross, Kat Hurley-Walker, Natasha Seymour, Nick Callingham, J.R. Galvin, Tim Johnston-Hollitt, Melanie |
| author_sort | Ross, Kat |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Characterizing spectral variability of radio sources is a technique that offers the ability to determine the astrophysics of the intervening media, source structure, emission, and absorption processes. We present broadband (0.072-10 GHz) spectral variability of 15 peaked-spectrum (PS) sources with the Australia Telescope Compact Array (ATCA) and the Murchison Widefield Array (MWA). These 15 PS sources were observed quasi-contemporaneously with ATCA and the MWA four to six times during 2020 with approximately a monthly cadence. Variability was not detected at 1-10 GHz frequencies but 13 of the 15 targets show significant variability with the MWA at megahertz frequencies. We conclude the majority of variability seen at megahertz frequencies is due to refractive interstellar scintillation of a compact component ∼25 mas across. We also identify four PS sources that show a change in their spectral shape at megahertz frequencies. Three of these sources are consistent with a variable optical depth from an inhomogeneous free-free absorbing cloud around the source. One PS source with a variable spectral shape at megahertz frequencies is consistent with an ejection travelling along the jet. We present spectral variability as a method for determining the physical origins of observed variability and for providing further evidence to support absorption models for PS sources where spectral modelling alone is insufficient. |
| first_indexed | 2025-11-14T11:37:40Z |
| format | Journal Article |
| id | curtin-20.500.11937-91782 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:37:40Z |
| publishDate | 2022 |
| publisher | OXFORD UNIV PRESS |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-917822023-05-16T02:58:30Z Wide-band spectral variability of peaked spectrum sources Ross, Kat Hurley-Walker, Natasha Seymour, Nick Callingham, J.R. Galvin, Tim Johnston-Hollitt, Melanie Science & Technology Physical Sciences Astronomy & Astrophysics scattering galaxies: active radio continuum: galaxies radio continuum: general radio continuum: ISM COMPACT STEEP-SPECTRUM MOLONGLO REFERENCE CATALOG MURCHISON WIDEFIELD ARRAY RADIO-SOURCES INTERSTELLAR SCINTILLATION SKY JETS CONSTRAINTS ABSORPTION QUASARS astro-ph.GA astro-ph.GA astro-ph.HE Characterizing spectral variability of radio sources is a technique that offers the ability to determine the astrophysics of the intervening media, source structure, emission, and absorption processes. We present broadband (0.072-10 GHz) spectral variability of 15 peaked-spectrum (PS) sources with the Australia Telescope Compact Array (ATCA) and the Murchison Widefield Array (MWA). These 15 PS sources were observed quasi-contemporaneously with ATCA and the MWA four to six times during 2020 with approximately a monthly cadence. Variability was not detected at 1-10 GHz frequencies but 13 of the 15 targets show significant variability with the MWA at megahertz frequencies. We conclude the majority of variability seen at megahertz frequencies is due to refractive interstellar scintillation of a compact component ∼25 mas across. We also identify four PS sources that show a change in their spectral shape at megahertz frequencies. Three of these sources are consistent with a variable optical depth from an inhomogeneous free-free absorbing cloud around the source. One PS source with a variable spectral shape at megahertz frequencies is consistent with an ejection travelling along the jet. We present spectral variability as a method for determining the physical origins of observed variability and for providing further evidence to support absorption models for PS sources where spectral modelling alone is insufficient. 2022 Journal Article http://hdl.handle.net/20.500.11937/91782 10.1093/mnras/stac819 English http://purl.org/au-research/grants/arc/FT190100231 OXFORD UNIV PRESS fulltext |
| spellingShingle | Science & Technology Physical Sciences Astronomy & Astrophysics scattering galaxies: active radio continuum: galaxies radio continuum: general radio continuum: ISM COMPACT STEEP-SPECTRUM MOLONGLO REFERENCE CATALOG MURCHISON WIDEFIELD ARRAY RADIO-SOURCES INTERSTELLAR SCINTILLATION SKY JETS CONSTRAINTS ABSORPTION QUASARS astro-ph.GA astro-ph.GA astro-ph.HE Ross, Kat Hurley-Walker, Natasha Seymour, Nick Callingham, J.R. Galvin, Tim Johnston-Hollitt, Melanie Wide-band spectral variability of peaked spectrum sources |
| title | Wide-band spectral variability of peaked spectrum sources |
| title_full | Wide-band spectral variability of peaked spectrum sources |
| title_fullStr | Wide-band spectral variability of peaked spectrum sources |
| title_full_unstemmed | Wide-band spectral variability of peaked spectrum sources |
| title_short | Wide-band spectral variability of peaked spectrum sources |
| title_sort | wide-band spectral variability of peaked spectrum sources |
| topic | Science & Technology Physical Sciences Astronomy & Astrophysics scattering galaxies: active radio continuum: galaxies radio continuum: general radio continuum: ISM COMPACT STEEP-SPECTRUM MOLONGLO REFERENCE CATALOG MURCHISON WIDEFIELD ARRAY RADIO-SOURCES INTERSTELLAR SCINTILLATION SKY JETS CONSTRAINTS ABSORPTION QUASARS astro-ph.GA astro-ph.GA astro-ph.HE |
| url | http://purl.org/au-research/grants/arc/FT190100231 http://hdl.handle.net/20.500.11937/91782 |