Interplanetary scintillation studies with the Murchison Widefield Array - II. Properties of sub-arcsecond compact sources at low radio frequencies
We report the first astrophysical application of the technique of wide-field Interplanetary Scintillation (IPS) with the Murchison Widefield Array (MWA). This powerful technique allows us to identify and measure sub-arcsecond compact components in low-frequency radio sources across large areas of sk...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Journal Article |
| Published: |
Oxford University Press
2018
|
| Online Access: | http://hdl.handle.net/20.500.11937/67469 |
| _version_ | 1848761574109478912 |
|---|---|
| author | Chhetri, Rajan Morgan, John Ekers, Ronald Macquart, Jean-Pierre Sadler, E. Giroletti, M. Callingham, J. Tingay, Steven |
| author_facet | Chhetri, Rajan Morgan, John Ekers, Ronald Macquart, Jean-Pierre Sadler, E. Giroletti, M. Callingham, J. Tingay, Steven |
| author_sort | Chhetri, Rajan |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We report the first astrophysical application of the technique of wide-field Interplanetary Scintillation (IPS) with the Murchison Widefield Array (MWA). This powerful technique allows us to identify and measure sub-arcsecond compact components in low-frequency radio sources across large areas of sky without the need for long-baseline interferometry or ionospheric calibration. We present the results of a five-minute observation of a 30x30 sq. deg MWA field at 162 MHz with 0.5 second time resolution. Of the 2550 continuum sources detected in this field, 302 (12 per cent) show rapid fluctuations caused by IPS. We find that at least 32% of bright low-frequency radio sources contain a sub-arcsec compact component that contributes over 40% of the total flux density. Perhaps surprisingly, peaked-spectrum radio sources are the dominant population among the strongly-scintillating, low-frequency sources in our sample. While gamma-ray AGN are generally compact, flat-spectrum radio sources at higher frequencies, the 162 MHz properties of many of the Fermi blazars in our field are consistent with a compact component embedded within more extended low-frequency emission. The detection of a known pulsar in our field shows that the wide-field IPS technique is at the threshold of sensitivity needed to detect new pulsars using image plane analysis, and scaling the current MWA sensitivity to that expected for SKA-low implies that large IPS-based pulsar searches will be feasible with SKA. Calibration strategies for the SKA require a better knowledge of the space density of compact sources at low radio frequencies, which IPS observations can now provide. |
| first_indexed | 2025-11-14T10:33:50Z |
| format | Journal Article |
| id | curtin-20.500.11937-67469 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:33:50Z |
| publishDate | 2018 |
| publisher | Oxford University Press |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-674692018-09-26T06:28:45Z Interplanetary scintillation studies with the Murchison Widefield Array - II. Properties of sub-arcsecond compact sources at low radio frequencies Chhetri, Rajan Morgan, John Ekers, Ronald Macquart, Jean-Pierre Sadler, E. Giroletti, M. Callingham, J. Tingay, Steven We report the first astrophysical application of the technique of wide-field Interplanetary Scintillation (IPS) with the Murchison Widefield Array (MWA). This powerful technique allows us to identify and measure sub-arcsecond compact components in low-frequency radio sources across large areas of sky without the need for long-baseline interferometry or ionospheric calibration. We present the results of a five-minute observation of a 30x30 sq. deg MWA field at 162 MHz with 0.5 second time resolution. Of the 2550 continuum sources detected in this field, 302 (12 per cent) show rapid fluctuations caused by IPS. We find that at least 32% of bright low-frequency radio sources contain a sub-arcsec compact component that contributes over 40% of the total flux density. Perhaps surprisingly, peaked-spectrum radio sources are the dominant population among the strongly-scintillating, low-frequency sources in our sample. While gamma-ray AGN are generally compact, flat-spectrum radio sources at higher frequencies, the 162 MHz properties of many of the Fermi blazars in our field are consistent with a compact component embedded within more extended low-frequency emission. The detection of a known pulsar in our field shows that the wide-field IPS technique is at the threshold of sensitivity needed to detect new pulsars using image plane analysis, and scaling the current MWA sensitivity to that expected for SKA-low implies that large IPS-based pulsar searches will be feasible with SKA. Calibration strategies for the SKA require a better knowledge of the space density of compact sources at low radio frequencies, which IPS observations can now provide. 2018 Journal Article http://hdl.handle.net/20.500.11937/67469 10.1093/mnras/stx2864 Oxford University Press fulltext |
| spellingShingle | Chhetri, Rajan Morgan, John Ekers, Ronald Macquart, Jean-Pierre Sadler, E. Giroletti, M. Callingham, J. Tingay, Steven Interplanetary scintillation studies with the Murchison Widefield Array - II. Properties of sub-arcsecond compact sources at low radio frequencies |
| title | Interplanetary scintillation studies with the Murchison Widefield Array - II. Properties of sub-arcsecond compact sources at low radio frequencies |
| title_full | Interplanetary scintillation studies with the Murchison Widefield Array - II. Properties of sub-arcsecond compact sources at low radio frequencies |
| title_fullStr | Interplanetary scintillation studies with the Murchison Widefield Array - II. Properties of sub-arcsecond compact sources at low radio frequencies |
| title_full_unstemmed | Interplanetary scintillation studies with the Murchison Widefield Array - II. Properties of sub-arcsecond compact sources at low radio frequencies |
| title_short | Interplanetary scintillation studies with the Murchison Widefield Array - II. Properties of sub-arcsecond compact sources at low radio frequencies |
| title_sort | interplanetary scintillation studies with the murchison widefield array - ii. properties of sub-arcsecond compact sources at low radio frequencies |
| url | http://hdl.handle.net/20.500.11937/67469 |