DEGREE OF POLARIZATION AND SOURCE COUNTS OF FAINT RADIO SOURCES FROM STACKING POLARIZED INTENSITY

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dc.contributor.authorStil, J M
dc.contributor.authorKeller, B W
dc.contributor.authorGeorge, S J
dc.contributor.authorTaylor, A R
dc.date.accessioned2021-10-08T07:20:40Z
dc.date.available2021-10-08T07:20:40Z
dc.date.issued2014
dc.description.abstractWe present stacking polarized intensity as a means to study the polarization of sources that are too faint to be detected individually in surveys of polarized radio sources. Stacking offers not only high sensitivity to the median signal of a class of radio sources, but also avoids a detection threshold in polarized intensity, and therefore an arbitrary exclusion of source with a low percentage of polarization. Correction for polarization bias is done through a Monte Carlo analysis and tested on a simulated survey. We show that the non-linear relation between the real polarized signal and the detected signal requires knowledge of the shape of the distribution of fractional polarization, which we constrain using the ratio of the upper quartile to the lower quartile of the distribution of stacked polarized intensities. Stacking polarized intensity for NVSS sources down to the detection limit in Stokes I, we find a gradual increase in median fractional polarization that is consistent with a trend that was noticed before for bright NVSS sources, but is much more gradual than found by previous deep surveys of radio polarization. Consequently, the polarized radio source counts derived from our stacking experiment predict fewer polarized radio sources for future surveys with the Square Kilometre Array and its pathfinders.
dc.identifier.apacitationStil, J. M., Keller, B. W., George, S. J., & Taylor, A. R. (2014). DEGREE OF POLARIZATION AND SOURCE COUNTS OF FAINT RADIO SOURCES FROM STACKING POLARIZED INTENSITY. <i>The Astrophysical Journal</i>, 787(2), 99 - 177. http://hdl.handle.net/11427/34978en_ZA
dc.identifier.chicagocitationStil, J M, B W Keller, S J George, and A R Taylor "DEGREE OF POLARIZATION AND SOURCE COUNTS OF FAINT RADIO SOURCES FROM STACKING POLARIZED INTENSITY." <i>The Astrophysical Journal</i> 787, 2. (2014): 99 - 177. http://hdl.handle.net/11427/34978en_ZA
dc.identifier.citationStil, J.M., Keller, B.W., George, S.J. & Taylor, A.R. 2014. DEGREE OF POLARIZATION AND SOURCE COUNTS OF FAINT RADIO SOURCES FROM STACKING POLARIZED INTENSITY. <i>The Astrophysical Journal.</i> 787(2):99 - 177. http://hdl.handle.net/11427/34978en_ZA
dc.identifier.issn0004-637X
dc.identifier.issn1538-4357
dc.identifier.ris TY - Journal Article AU - Stil, J M AU - Keller, B W AU - George, S J AU - Taylor, A R AB - We present stacking polarized intensity as a means to study the polarization of sources that are too faint to be detected individually in surveys of polarized radio sources. Stacking offers not only high sensitivity to the median signal of a class of radio sources, but also avoids a detection threshold in polarized intensity, and therefore an arbitrary exclusion of source with a low percentage of polarization. Correction for polarization bias is done through a Monte Carlo analysis and tested on a simulated survey. We show that the non-linear relation between the real polarized signal and the detected signal requires knowledge of the shape of the distribution of fractional polarization, which we constrain using the ratio of the upper quartile to the lower quartile of the distribution of stacked polarized intensities. Stacking polarized intensity for NVSS sources down to the detection limit in Stokes I, we find a gradual increase in median fractional polarization that is consistent with a trend that was noticed before for bright NVSS sources, but is much more gradual than found by previous deep surveys of radio polarization. Consequently, the polarized radio source counts derived from our stacking experiment predict fewer polarized radio sources for future surveys with the Square Kilometre Array and its pathfinders. DA - 2014 DB - OpenUCT DP - University of Cape Town IS - 2 J1 - The Astrophysical Journal LK - https://open.uct.ac.za PY - 2014 SM - 0004-637X SM - 1538-4357 T1 - DEGREE OF POLARIZATION AND SOURCE COUNTS OF FAINT RADIO SOURCES FROM STACKING POLARIZED INTENSITY TI - DEGREE OF POLARIZATION AND SOURCE COUNTS OF FAINT RADIO SOURCES FROM STACKING POLARIZED INTENSITY UR - http://hdl.handle.net/11427/34978 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/34978
dc.identifier.vancouvercitationStil JM, Keller BW, George SJ, Taylor AR. DEGREE OF POLARIZATION AND SOURCE COUNTS OF FAINT RADIO SOURCES FROM STACKING POLARIZED INTENSITY. The Astrophysical Journal. 2014;787(2):99 - 177. http://hdl.handle.net/11427/34978.en_ZA
dc.language.isoeng
dc.publisher.departmentDepartment of Astronomy
dc.publisher.facultyFaculty of Science
dc.sourceThe Astrophysical Journal
dc.source.journalissue2
dc.source.journalvolume787
dc.source.pagination99 - 177
dc.source.urihttps://dx.doi.org/10.1088/0004-637X/787/2/99
dc.subject.otherastrophysics
dc.subject.othercosmology and astronomy
dc.subject.othercorrections
dc.subject.otherdata analysis
dc.subject.otherdetection
dc.subject.otherdistribution
dc.subject.othergalaxies
dc.subject.othermagnetic fields
dc.subject.othermonte carlo method
dc.subject.othernonlinear problems
dc.subject.otherpolarization
dc.subject.othersensitivity
dc.subject.othersimulation
dc.subject.othersky
dc.titleDEGREE OF POLARIZATION AND SOURCE COUNTS OF FAINT RADIO SOURCES FROM STACKING POLARIZED INTENSITY
dc.typeJournal Article
uct.type.publicationResearch
uct.type.resourceJournal Article
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