Imperial College London
Portrait Picture

Dr Jonathan R. Pritchard

Faculty of Natural Sciences, Department of Physics

Reader in Astrophysics
 
 
 
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Contact

 

+44 (0)20 7594 7557j.pritchard Website CV

 
 
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Location

 

1018CBlackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Harker:2015:mnras/stv2630,
author = {Harker, GJA and Mirocha, J and Burns, JO and Pritchard, JR},
doi = {mnras/stv2630},
journal = {Monthly Notices of the Royal Astronomical Society},
pages = {3829--3840},
title = {Parametrizations of the 21-cm global signal and parameter estimation from single-dipole experiments},
url = {http://dx.doi.org/10.1093/mnras/stv2630},
volume = {455},
year = {2015}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - One approach to extracting the global 21-cm signal from total-power measurements at low radio frequencies is to parametrize the different contributions to the data and then fit for these parameters. We examine parametrizations of the 21-cm signal itself, and propose one based on modelling the Ly α background, intergalactic medium temperature and hydrogen ionized fraction using tanh functions. This captures the shape of the signal from a physical modelling code better than an earlier parametrization based on interpolating between maxima and minima of the signal, and imposes a greater level of physical plausibility. This allows less biased constraints on the turning points of the signal, even though these are not explicitly fit for. Biases can also be alleviated by discarding information which is less robustly described by the parametrization, for example by ignoring detailed shape information coming from the covariances between turning points or from the high-frequency parts of the signal, or by marginalizing over the high-frequency parts of the signal by fitting a more complex foreground model. The fits are sufficiently accurate to be usable for experiments gathering 1000 h of data, though in this case it may be important to choose observing windows which do not include the brightest areas of the foregrounds. Our assumption of pointed, single-antenna observations and very broad-band fitting makes these results particularly applicable to experiments such as the Dark Ages Radio Explorer, which would study the global 21-cm signal from the clean environment of a low lunar orbit, taking data from the far side.
AU  - Harker,GJA
AU  - Mirocha,J
AU  - Burns,JO
AU  - Pritchard,JR
DO  - mnras/stv2630
EP  - 3840
PY  - 2015///
SN  - 0035-8711
SP  - 3829
TI  - Parametrizations of the 21-cm global signal and parameter estimation from single-dipole experiments
T2  - Monthly Notices of the Royal Astronomical Society
UR  - http://dx.doi.org/10.1093/mnras/stv2630
UR  - http://hdl.handle.net/10044/1/53293
VL  - 455
ER  -
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