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Abstract:
I will begin with a broad-based introduction to some of the big open
questions in cosmology, and illustrate how upcoming experiments are
well-poised to help answer them, especially at the Cosmic Dawn — the
birth of the first galaxies in our Universe — widely believed to be
the 'final frontier' of cosmological surveys today. This period —
about a hundred million years after the Big Bang — is primarily
accessible due to radiation from hydrogen, the most abundant element
in the Universe, which emits at a wavelength of 21 cm, in the radio
band. An exquisite investigation of the Cosmic Dawn will soon become
possible with an emerging technique called intensity mapping (IM),
which measures the integrated 21 cm emission from all sources, using
large arrays of radio telescopes. A particular advantage of IM is that
it provides a tomographic, or three-dimensional picture of the
Universe, unlocking significantly more information than we presently
have from galaxy surveys. I will overview the latest advances in
research related to the evolution of hydrogen over 12 billion years of
cosmic time, involving a novel data-driven framework to interpret
current and future observations. This allows us to fully utilize our
present knowledge of astrophysics in order to develop cosmological
forecasts from IM. Apart from offering key insights into the nature
of the first galaxies, this opens up the exciting possibility of
testing theories of fundamental physics from the Cosmic Dawn.
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