TY - JOUR
T1 - The discovery of diffuse radio polarization structures in the nrao very large array sky survey
AU - Rudnick, Lawrence
AU - Brown, Shea
PY - 2009
Y1 - 2009
N2 - We have developed a method for recovering polarization structures from the NRAO Very Large Array Sky Survey (NVSS) on larger angular scales than the nominal 15 arcmin survey limit. The technique depends on the existence of smaller-scale fluctuations in the polarization angle, to which the interferometer is sensitive, while the undetected total intensity of the structures can be arbitrarily large. We recover the large-scale structure of the polarized Milky Way, as seen in single-dish surveys, as well as a wide variety of smaller-scale Galactic and extragalactic features. We present a brief discussion of the uncertainties and limitations of the reprocessed NVSS polarization survey, a comparison of single-dish and NVSS results, and a sampling of the new polarization structures. We show a companion feature 1.8 Mpc outside of Abell cluster 3744, apparent Mpc-scale extensions to the tailed radio galaxy 3C31, a possible new giant Galactic loop, and a new bright polarized patch in supernova remnant CTA1. We note that there is little quantitative information from these detections, and follow-up investigations would be necessary to measure reliable polarized fluxes and position angles. Some of the new features discovered in this NVSS reanalysis could provide a foreground for cosmic microwave background polarization studies, but the internal foreground modeling for the next generation of experiments should have no difficulty accounting for them.
AB - We have developed a method for recovering polarization structures from the NRAO Very Large Array Sky Survey (NVSS) on larger angular scales than the nominal 15 arcmin survey limit. The technique depends on the existence of smaller-scale fluctuations in the polarization angle, to which the interferometer is sensitive, while the undetected total intensity of the structures can be arbitrarily large. We recover the large-scale structure of the polarized Milky Way, as seen in single-dish surveys, as well as a wide variety of smaller-scale Galactic and extragalactic features. We present a brief discussion of the uncertainties and limitations of the reprocessed NVSS polarization survey, a comparison of single-dish and NVSS results, and a sampling of the new polarization structures. We show a companion feature 1.8 Mpc outside of Abell cluster 3744, apparent Mpc-scale extensions to the tailed radio galaxy 3C31, a possible new giant Galactic loop, and a new bright polarized patch in supernova remnant CTA1. We note that there is little quantitative information from these detections, and follow-up investigations would be necessary to measure reliable polarized fluxes and position angles. Some of the new features discovered in this NVSS reanalysis could provide a foreground for cosmic microwave background polarization studies, but the internal foreground modeling for the next generation of experiments should have no difficulty accounting for them.
KW - Galaxies: active
KW - Galaxies: clusters: general
KW - Galaxy: structure
KW - ISM: magnetic fields
KW - Intergalactic medium
KW - Supernova remnants
KW - Techniques: polarimetric
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U2 - 10.1088/0004-6256/137/1/145
DO - 10.1088/0004-6256/137/1/145
M3 - Article
AN - SCOPUS:66149087385
SN - 0004-6256
VL - 137
SP - 145
EP - 156
JO - Astronomical Journal
JF - Astronomical Journal
IS - 1
ER -