Simulating the Epoch of Reionization for LOFAR and SKA
Title: |
Simulating the Epoch of Reionization for LOFAR and SKA |
DNr: |
SNIC 2014/11-38 |
Project Type: |
SNIC Large Compute |
Principal Investigator: |
Garrelt Mellema <garrelt.mellema@astro.su.se> |
Affiliation: |
Stockholms universitet |
Duration: |
2015-01-01 – 2016-01-01 |
Classification: |
10305 |
Keywords: |
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Abstract
About 100 million years after the Big Bang, gravitational collapse
from the initial density fluctuations in the Universe produced the
first structures (proto-galaxies) capable of forming stars. The
radiation produced in these proto-galaxies partly escaped and started
to ionize the immediate surroundings of each proto-galaxy. As more and
more proto-galaxies form, these regions start to overlap and
grow. This process is known as the Reionization of the Universe and
lasted until 1000 million years after the Big Bang, when all of the
material between the galaxies had become ionized. This is the state it
has remained in until the present day. This process is not well
understood and currently at the forefront of cosmological research as
a number of observational experiments such as the European LOFAR
radio telescope aim at detecting signposts from the Reionization process.
In this project we perform large scale simulations of the reionization
process, by calculating the transfer of ionizing photons through the
evolving three-dimensional density field of a representative volume of
the Universe. These are obtained from (previously run) large
cosmological simulations. The radiation sources (proto-galaxies) are
also found from these cosmological simulations. In a typical volume,
towards the end of Reionization, millions of sources are
present. Numerical simulations are the only way to properly deal with
the complex structure of the intergalactic density field, and the
spatial distribution of sources, which is not random but
clustered. The result of the simulations is a history of the
distribution of ionized material from when the first sources formed to
end of Reionization. Such histories are subsequently used to
characterize the expected observational signals, which helps in the
design and future analysis of the observational experiments.
In this project we will perform two types of simulations. The first
type will be used to create a framework to interpret the LOFAR results
in terms of the properties of sources of reionization. The second type
will investigate the how x-ray radiation produced in star forming
(proto-)galaxies heated the still mostly neutral medium during the
earlier stages of reionization. The latter process is important for
the LOFAR measurements as a cold medium will give an absorption signal
whereas a heated medium will give an emission signal.