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Detection of six rapidly scintillating active galactic nuclei and the diminished variability of J1819+3845

Koay, J. Y.; Bignall, H. E.; Macquart, J. P; Jauncey, David; Rickett, B. J.; Lovell, J

Description

The extreme, intra-hour and >10% rms flux density scintillation observed in AGNs such as PKS 0405-385, J1819+3845 and PKS 1257-326 at cm wavelengths has been attributed to scattering in highly turbulent, nearby regions in the interstellar medium. Such behavior has been found to be rare. We searched for rapid scintillators among 128 flat spectrum AGNs and analyzed their properties to determine the origin of such rapid and large amplitude radio scintillation. The sources were observed at the VLA...[Show more]

dc.contributor.authorKoay, J. Y.
dc.contributor.authorBignall, H. E.
dc.contributor.authorMacquart, J. P
dc.contributor.authorJauncey, David
dc.contributor.authorRickett, B. J.
dc.contributor.authorLovell, J
dc.date.accessioned2015-12-10T22:21:00Z
dc.identifier.issn0004-6361
dc.identifier.urihttp://hdl.handle.net/1885/52189
dc.description.abstractThe extreme, intra-hour and >10% rms flux density scintillation observed in AGNs such as PKS 0405-385, J1819+3845 and PKS 1257-326 at cm wavelengths has been attributed to scattering in highly turbulent, nearby regions in the interstellar medium. Such behavior has been found to be rare. We searched for rapid scintillators among 128 flat spectrum AGNs and analyzed their properties to determine the origin of such rapid and large amplitude radio scintillation. The sources were observed at the VLA at 4.9 and 8.4 GHz simultaneously at two hour intervals over 11 days. We detected six rapid scintillators with characteristic time-scales of <2 h, none of which have rms variations >10%. We found strong lines of evidence linking rapid scintillation to the presence of nearby scattering regions, estimated to be <12 pc away for ∼200 μas sources and <250 pc away for ∼10 μas sources. We attribute the scarcity of rapid and large amplitude scintillators to the requirement of additional constraints, including large source compact fractions. J1819+3845 was found to display ∼2% rms variations at ∼6 h time-scales superposed on longer >11 day variations, suggesting that the highly turbulent cloud responsible for its extreme scintillation has moved away, with its scintillation now caused by a more distant screen 50 to 150 pc away.
dc.publisherSpringer
dc.rightsAuthor/s retain copyright
dc.sourceAstronomy and Astrophysics
dc.subjectKeywords: Galaxies : active; ISM: structure; Quasars: general; Quasars: individual; Radio continuum: ISM; Galaxies; Ionization; Scattering; Scintillation counters; Scintillation Galaxies: active; ISM: structure; Quasars: general; Quasars: individual: J1819+3845; Radio continuum: ISM; Scattering
dc.titleDetection of six rapidly scintillating active galactic nuclei and the diminished variability of J1819+3845
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume534
dc.date.issued2011
local.identifier.absfor020103 - Cosmology and Extragalactic Astronomy
local.identifier.ariespublicationu3356449xPUB241
local.type.statusPublished Version
local.contributor.affiliationKoay, J. Y., Curtin University
local.contributor.affiliationBignall, H. E., Curtin University
local.contributor.affiliationMacquart, J. P, Curtin University
local.contributor.affiliationJauncey, David, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationRickett, B. J. , University of California
local.contributor.affiliationLovell, J, University of Tasmania
local.bibliographicCitation.startpageL1
local.bibliographicCitation.lastpage4
local.identifier.doi10.1051/0004-6361/201117805
local.identifier.absseo970102 - Expanding Knowledge in the Physical Sciences
dc.date.updated2016-02-24T09:54:48Z
local.identifier.scopusID2-s2.0-80053010890
local.identifier.thomsonID000296554800149
dcterms.accessRightsOpen Access
CollectionsANU Research Publications

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