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Subtraction of Bright Point Sources from Synthesis Images of the Epoch of Reionization

Published online by Cambridge University Press:  02 January 2013

B. Pindor ,
J. S. B. Wyithe ,
D. A. Mitchell ,
S. M. Ord ,
R. B. Wayth  and
L. J. Greenhill
B. Pindor*
Affiliation:
University of Melbourne, School of Physics, Parkville 3010, Australia
J. S. B. Wyithe
Affiliation:
University of Melbourne, School of Physics, Parkville 3010, Australia
D. A. Mitchell
Affiliation:
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138-1516, USA
S. M. Ord
Affiliation:
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138-1516, USA
R. B. Wayth
Affiliation:
ICRAR/Curtin Institute of Radio Astronomy, GPO Box U1987, Perth, WA 6845, Australia
L. J. Greenhill
Affiliation:
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138-1516, USA
*
DCorresponding author. Email: [email protected]
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Abstract

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Bright point sources associated with extragalactic active galactic nuclei and radio galaxies are an important foreground for low-frequency radio experiments aimed at detecting the redshifted 21-cm emission from neutral hydrogen during the epoch of reionization. The frequency dependence of the synthesized beam implies that the sidelobes of these sources will move across the field of view as a function of observing frequency, hence frustrating line-of-sight foreground subtraction techniques. We describe a method for subtracting these point sources from dirty maps produced by an instrument such as the MWA. This technique combines matched filters with an iterative centroiding scheme to locate and characterize point sources in the presence of a diffuse background. Simulations show that this technique can improve the dynamic range of epoch-of-reionization maps by 2—3 orders of magnitude.

Keywords

cosmology: diffuse radiationmethods: data analysis
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Volume 28 , Issue 1 , 2011 , pp. 46 - 57
Copyright
Copyright © Astronomical Society of Australia 2011

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