1. RRI Digital Repository
  2. 04. Astronomy and Astrophysics
  3. Research Papers (A&A)
Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/7130
Full metadata record
DC FieldValueLanguage
dc.contributor.authorBell, M.E.-
dc.contributor.authorDeshpande, A.A.-
dc.contributor.authorPrabu, T.-
dc.contributor.authorUdaya Shankar, N.-
dc.contributor.authorSrivani, K.S.-
dc.contributor.authorSubrahmanyan, Ravi-
dc.contributor.author+ 35 Co-authors-
dc.date.accessioned2019-01-23T20:42:21Z-
dc.date.available2019-01-23T20:42:21Z-
dc.date.issued2019-01-11-
dc.identifier.citationMonthly Notices of the Royal Astronomical Society, 2018, Vol. 482, p2484–2501en_US
dc.identifier.issn0035-8711-
dc.identifier.issn1365-2966 - (online)-
dc.identifier.urihttp://hdl.handle.net/2289/7130-
dc.descriptionOpen Accessen_US
dc.description.abstractWe report on a search for low-frequency radio variability in 944 bright (>4 Jy at 154 MHz) unresolved, extragalactic radio sources monitored monthly for several years with the Murchison Widefield Array. In the majority of sources, we find very low levels of variability with typical modulation indices <5 per cent. We detect 15 candidate low-frequency variables that show significant long-term variability (>2.8 yr) with time-averaged modulation indices \overline{M}=3.1 - 7.1 per cent. With 7/15 of these variable sources having peaked spectral energy distributions, and only 5.7 per cent of the overall sample having peaked spectra, we find an increase in the prevalence of variability in this spectral class. We conclude that the variability seen in this survey is most probably a consequence of refractive interstellar scintillation and that these objects must have the majority of their flux density contained within angular diameters less than 50 milliarcsec (which we support with multiwavelength data). At 154 MHz, we demonstrate that interstellar scintillation time-scales become long (˜decades) and have low modulation indices, while synchrotron-driven variability can only produce dynamic changes on time-scales of hundreds of years, with flux density changes less than one milli-jansky (without relativistic boosting). From this work, we infer that the low-frequency extragalactic southern sky, as seen by SKA-Low, will be non-variable on time-scales shorter than 1 yr.en_US
dc.language.isoenen_US
dc.publisherOxford University Press on behalf of the Royal Astronomical Societyen_US
dc.relation.urihttp://adsabs.harvard.edu/abs/2019MNRAS.482.2484Ben_US
dc.relation.urihttps://arxiv.org/abs/1810.10152en_US
dc.relation.urihttps://doi.org/10.1093/mnras/sty2801en_US
dc.rights2018 The Author(s)en_US
dc.subjectradio continuumen_US
dc.subjectgalaxiesen_US
dc.subjecttransientsen_US
dc.subjectISMen_US
dc.titleThe Murchison Widefield Array Transients Survey (MWATS). A search for low-frequency variability in a bright Southern hemisphere sampleen_US
dc.typeArticleen_US
Appears in Collections:Research Papers (A&A)

Files in This Item:
File Description SizeFormat 
2019_MNRAS_Vol.482_p2484-2501.pdfOpen Access2.56 MBAdobe PDFView/Open
Show simple item record


Items in RRI Digital Repository are protected by copyright, with all rights reserved, unless otherwise indicated.