Measuring ultra-large scale effects in the presence of 21cm intensity mapping foregrounds. (arXiv:2011.11510v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Fonseca_J/0/1/0/all/0/1">José Fonseca</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liguori_M/0/1/0/all/0/1">Michele Liguori</a>
HI intensity mapping will provide maps of the large scale distribution of
neutral hydrogen in the universe. These are prime candidates to be used to
constrain primordial non-Gaussianity using the Large Scale Structure of the
Universe as well as to provide further tests of Einstein’s theory of Gravity.
But HI maps are contaminated by foregrounds which can be several orders of
magnitude above the cosmological signal. Here we quantify how degenerated are
the large-scale effects ($f_{rm NL}$ and GR effects) with the residual
foregrounds. We conclude that a joint analyses does not provide a catastrophic
degradation of constraints and provides a framework to determine the marginal
errors of large scale effects in the presence of foregrounds. Similarly, we
concluded that the macroscopical properties of the foregrounds can be measured
with high precision. Notwithstanding, such results are highly dependent on
accurate forward modeling of the foregrounds, which incorrectly done
catastrophically bias the best fit values of cosmological parameters,
foregrounds’ parameterizations, and large-scale effects.
HI intensity mapping will provide maps of the large scale distribution of
neutral hydrogen in the universe. These are prime candidates to be used to
constrain primordial non-Gaussianity using the Large Scale Structure of the
Universe as well as to provide further tests of Einstein’s theory of Gravity.
But HI maps are contaminated by foregrounds which can be several orders of
magnitude above the cosmological signal. Here we quantify how degenerated are
the large-scale effects ($f_{rm NL}$ and GR effects) with the residual
foregrounds. We conclude that a joint analyses does not provide a catastrophic
degradation of constraints and provides a framework to determine the marginal
errors of large scale effects in the presence of foregrounds. Similarly, we
concluded that the macroscopical properties of the foregrounds can be measured
with high precision. Notwithstanding, such results are highly dependent on
accurate forward modeling of the foregrounds, which incorrectly done
catastrophically bias the best fit values of cosmological parameters,
foregrounds’ parameterizations, and large-scale effects.
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