Initial LOFAR observations of epoch of reionization windows II. Diffuse polarized emission in the ELAIS-N1 field
Artikel i vetenskaplig tidskrift, 2014
Aims. This study aims to characterise the polarized foreground emission in the ELAIS-N1 field and to address its possible implications or extracting of the cosmological 21 cm signal from the LOw-Frequency ARray - Epoch of Reionization (LOFAR-EoR) data Methods. We used the high band antennas of LOFAR to image this region and RM-synthesis to unravel structures of polarized emission at high Galactic latitudes. Results. The brightness temperature of the detected Galactic emission is on average similar to 4 K in polarized intensity and covers the range from -10 to +13 rad m(-2) in Faraday depth, The total polarized intensity and polarization angle show a wide range of morphological features. We have also used the Westerbork Synthesis Radio Telescope (WSRT) at 350 MHz to image the same region. The LOFAR and WSRT images show a similar complex morphology at comparable brightness levels, but their spatial correlation is very low. The fractional polarization at 150 MHz, expressed as a percentage of the total intensity, amounts to approximate to 1.5%. There is no indication of diffuse emission in total intensity in the interferometric data. in line with results at higher frequencies Conclusions. The wide frequency range. high angular resolution, and high sensitivity make LOFAR an exquisite instrument for studying Galactic polarized emission at a resolution of similar to 1-2 rad m(-2) in Faraday depth. The different polarized patterns observed at 150 MHz and 350 MHz are consistent with different source distributions along the line of sight wring in a variety of Faraday thin regions of emission. The presence of polarized foregrounds is a serious complication for epoch of reionization experiments. To avoid the leakage of polarized emission into total intensity, which can depend on frequency, we need to calibrate the instrumental polarization across the field of view to a small fraction of 1%.
Diffuse radiation
Radio continuum: ISM
Cosmology: observations
Techniques: interferometric
Dark ages, reionization, first stars
Techniques: polarimetric
Författare
V. Jelic
Rijksuniversiteit Groningen
Netherlands Institute for Radio Astronomy (ASTRON)
A. G. de Bruyn
Rijksuniversiteit Groningen
Netherlands Institute for Radio Astronomy (ASTRON)
M. Mevius
Rijksuniversiteit Groningen
F. B. Abdalla
University College London (UCL)
K. M. B. Asad
Rijksuniversiteit Groningen
G. Bernardi
Square Kilometre Array, South Africa
M. A. Brentjens
Netherlands Institute for Radio Astronomy (ASTRON)
S. Bus
Rijksuniversiteit Groningen
E. Chapman
University College London (UCL)
B. Ciardi
Max-Planck-Gesellschaft
S. Daiboo
Rijksuniversiteit Groningen
E. R. Fernandez
Rijksuniversiteit Groningen
A. Ghosh
Rijksuniversiteit Groningen
G. Harker
University of Colorado
H. Jensen
Stockholms universitet
S. Kazemi
Rijksuniversiteit Groningen
L. V. E. Koopmans
Rijksuniversiteit Groningen
P. Labropoulos
Rijksuniversiteit Groningen
O. Martinez-Rubi
Rijksuniversiteit Groningen
G. Mellema
Stockholms universitet
A. R. Offringa
Australian National University
ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)
V. N. Pandey
Netherlands Institute for Radio Astronomy (ASTRON)
A. H. Patil
Rijksuniversiteit Groningen
R. M. Thomas
Rijksuniversiteit Groningen
H. K. Vedantham
Rijksuniversiteit Groningen
V. Veligatla
Rijksuniversiteit Groningen
S. Yatawatta
Netherlands Institute for Radio Astronomy (ASTRON)
S. Zaroubi
Rijksuniversiteit Groningen
A. Alexov
Space Telescope Science Institute (STScI)
J. Anderson
Leibniz-Gemeinschaft
I. M. Avruch
Netherlands Institute for Space Research (SRON)
Rijksuniversiteit Groningen
R. Beck
Max-Planck-Gesellschaft
M. E. Bell
ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)
M. J. Bentum
Netherlands Institute for Radio Astronomy (ASTRON)
P. Best
University of Edinburgh
A. Bonafede
Universität Hamburg
J. Bregman
Netherlands Institute for Radio Astronomy (ASTRON)
F. Breitling
Leibniz-Gemeinschaft
J. Broderick
University of Southampton
W. N. Brouw
Netherlands Institute for Radio Astronomy (ASTRON)
Rijksuniversiteit Groningen
M. Brueggen
Universität Hamburg
H. R. Butcher
Australian National University
John Conway
Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium
F. De Gasperin
Universität Hamburg
E. de Geus
Netherlands Institute for Radio Astronomy (ASTRON)
A. Deller
Netherlands Institute for Radio Astronomy (ASTRON)
R. -J. Dettmar
Ruhr-Universität Bochum
S. Duscha
Netherlands Institute for Radio Astronomy (ASTRON)
J. Eislöffel
Thüringer Landessternwarte Tautenburg
D. Engels
Hamburger Sternwarte
H. Faleke
Radboud Universiteit
Netherlands Institute for Radio Astronomy (ASTRON)
R. A. Fallows
Netherlands Institute for Radio Astronomy (ASTRON)
R. Fender
University of Oxford
C. Ferrari
Université Nice Sophia Antipolis (UNS)
W. Frieswijk
Netherlands Institute for Radio Astronomy (ASTRON)
M. A. Garrett
Universiteit Leiden
Netherlands Institute for Radio Astronomy (ASTRON)
J. Griessmeier
Station de Radioastronomie de Nançay
Universite d'Orleans
A. W. Gunst
Netherlands Institute for Radio Astronomy (ASTRON)
J. P. Hamaker
Netherlands Institute for Radio Astronomy (ASTRON)
T. E. Hassall
University of Southampton
University of Manchester
M. Haverkorn
Radboud Universiteit
Universiteit Leiden
G. Heald
Netherlands Institute for Radio Astronomy (ASTRON)
J. W. T. Hessels
Netherlands Institute for Radio Astronomy (ASTRON)
Universiteit Van Amsterdam
M. Hoeft
Thüringer Landessternwarte Tautenburg
J.R. Hörandel
Radboud Universiteit
A. Horneffer
Max-Planck-Gesellschaft
A. van der Horst
Universiteit Van Amsterdam
M. Iacobelli
Universiteit Leiden
E. Juette
Ruhr-Universität Bochum
A. Karastergiou
University of Oxford
V. I. Kondratiev
Astro Space Center of Lebedev Physical Institute
Netherlands Institute for Radio Astronomy (ASTRON)
M. Kramer
University of Manchester
Max-Planck-Gesellschaft
M. Kuniyoshi
Max-Planck-Gesellschaft
G. Kuper
Netherlands Institute for Radio Astronomy (ASTRON)
J. van Leeuwen
Universiteit Van Amsterdam
Netherlands Institute for Radio Astronomy (ASTRON)
P. Maat
Netherlands Institute for Radio Astronomy (ASTRON)
G. Mann
Leibniz-Gemeinschaft
D. McKay-Bakowski
STFC Rutherford Appleton Laboratory
Oulun Yliopisto
J. P. MeKean
Rijksuniversiteit Groningen
Netherlands Institute for Radio Astronomy (ASTRON)
H. Mank
Netherlands Institute for Radio Astronomy (ASTRON)
A. Nelles
Radboud Universiteit
M. J. Morden
Netherlands Institute for Radio Astronomy (ASTRON)
H. Paas
Rijksuniversiteit Groningen
M. Pandey-Pornmier
Observatoire de Lyon
G. Pietka
University of Oxford
R. Pizzo
Netherlands Institute for Radio Astronomy (ASTRON)
A. G. Polatidis
Netherlands Institute for Radio Astronomy (ASTRON)
W. Reich
Max-Planck-Gesellschaft
H. Rottgering
Universiteit Leiden
A. Rowlinson
Universiteit Van Amsterdam
A. M. M. Scaife
University of Southampton
D. Schwarz
Universität Bielefeld
M. Serylak
University of Oxford
O. Smirnov
Rhodes University
Square Kilometre Array, South Africa
M. Steinmetz
Leibniz-Gemeinschaft
A. Stewart
University of Oxford
M. Tagger
Universite d'Orleans
Y. Tang
Netherlands Institute for Radio Astronomy (ASTRON)
C. Tasse
Observatoire de Paris-Meudon
S. ter Veen
Radboud Universiteit
S. Thoudam
Radboud Universiteit
C. Toribio
Netherlands Institute for Radio Astronomy (ASTRON)
R. Vermeulen
Netherlands Institute for Radio Astronomy (ASTRON)
C. Voeks
Leibniz-Gemeinschaft
R. J. van Weeren
Harvard-Smithsonian Center for Astrophysics
R. A. M. J. Wijers
Universiteit Van Amsterdam
S. J. Wijnholds
Netherlands Institute for Radio Astronomy (ASTRON)
O. Wucknitz
Max-Planck-Gesellschaft
Universität Bonn
P. Zarka
Observatoire de Paris-Meudon
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 568 A101Ämneskategorier (SSIF 2011)
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/201423998