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Probing the cosmic dawn and the epoch of reionization with the history and fluctuations of the hydrogen 21-cm line


One of the frontiers being explored by astronomy today is the
period between approximately 400000 years after the Big Bang, from
which time we can detect the cosmic microwave background (CMB)
radiation, and around one billion years after the Big Bang, when
early galaxies and quasars start to become visible to current
instruments, such as ALMA and the Wide Field Camera 3 on HST. The
most promising observational probe of this period is the redshifted
21-cm hyperfine line of atomic hydrogen.

The LOFAR telescope is now operational, and from its site in the
Netherlands will be able to detect 21-cm radiation from the latter
part of this period, the 'epoch of reionization' (EoR). Foreground
radiation at the same frequency is several orders of magnitude more
intense than the cosmological signal, however. Moreover, the data
will have low signal-to-noise and be filtered through a complex
instrument. As one of the core members of the LOFAR EoR key
project, I have developed techniques to extract information about
cosmology and reionization from the data, and applied them to
synthetic EoR observations. During the fellowship, I will continue
to develop and extend these methods with the help of the expertise
in data analysis and novel statistical methods at UCL, begin to
apply them to the real data which will start to arrive during the
period of the fellowship, and use them to learn about the EoR.

Other experiments are being proposed which would be able to probe
earlier parts of this period, the 'dark ages' and the 'cosmic
dawn'. I am a co-investigator on a satellite mission, the Dark Ages
Radio Explorer (DARE), which will be proposed to NASA's 2013
Explorer program. It would take a complementary approach to
LOFAR's, observing the sky-averaged 21-cm signal (rather than its
fluctuations) at even lower radio frequencies, with the aim of
learning about the very first stars and black holes. Analysing its
data presents a different challenge, and will also require novel

Call for proposal

See other projects for this call

Funding Scheme

MC-IEF - Intra-European Fellowships (IEF)


University College London
Gower Street
WC1E 6BT London
United Kingdom
Activity type
Higher or Secondary Education Establishments
EU contribution
€ 299 558,40
Administrative Contact
Giles Machell (Mr.)