Browsing by Subject "Reionization"
Now showing items 1-13 of 13
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Bayesian jackknife tests with a small number of subsets: application to HERA 21 cm power spectrum upper limits
(Monthly Notices of the Royal Astronomical Society, 2023)We present a Bayesian jackknife test for assessing the probability that a data set contains biased subsets, and, if so, which of the subsets are likely to be biased. The test can be used to assess the presence and likely ... -
Constraining the reionization history using deep learning from 21-cm tomography with the Square Kilometre Array
(Oxford University Press, 2020)Upcoming 21-cm surveys with the SKA1-LOW telescope will enable imaging of the neutral hydrogen distribution on cosmological scales in the early Universe. These surveys are expected to generate huge imaging data sets that ... -
Cosmic microwave background constraints on a physical model of reionization
(Oxford University Press, 2021)We study constraints on allowed reionization histories by comparing predictions of a physical seminumerical model with secondary temperature and polarization anisotropies of the cosmic microwave background (CMB). Our model ... -
Extracting the global signal from 21-cm fluctuations: the multitracer approach
(Oxford University Press, 2019)The multitracer technique employs a ratio of densities of two differently biased galaxy samples that trace the same underlying matter density field, and was proposed to alleviate the cosmic variance problem. Here, we propose ... -
Foreground modelling via Gaussian process regression: an application to HERA data
(Oxford University Press, 2020)The key challenge in the observation of the redshifted 21-cm signal from cosmic reionization is its separation from the much brighter foreground emission. Such separation relies on the different spectral properties of the ... -
Full-sky bispectrum in redshift space for 21cm intensity maps
(IOP Publishing, 2020)We compute the tree-level bispectrum of 21cm intensity mapping after reionisation. We work in directly observable angular and redshift space, focusing on equal-redshift correlations and thin redshift bins, for which the ... -
HERA Phase I Limits on the Cosmic 21 cm Signal: Constraints on Astrophysics and Cosmology during the Epoch of Reionization
(The American Astronomical Society., 2022)Recently, the Hydrogen Epoch of Reionization Array (HERA) has produced the experiment’s first upper limits on the power spectrum of 21 cm fluctuations at z ∼ 8 and 10. Here, we use several independent theoretical models ... -
Hiflow: Generating diverse hi maps and inferring cosmology while marginalizing over astrophysics using normalizing flows
(IOP Publishing, 2022)A wealth of cosmological and astrophysical information is expected from many ongoing and upcoming large-scale surveys. It is crucial to prepare for these surveys now and develop tools that can efficiently extract ... -
Improved upper limits on the 21 cm signal power spectrum of neutral hydrogen at z ≈ 9.1 from LOFAR
(Oxford University Press, 2020)A new upper limit on the 21 cm signal power spectrum at a redshift of z ≈ 9.1 is presented, based on 141 h of data obtained with the Low-Frequency Array (LOFAR). The analysis includes significant improvements in spectrally ... -
Patterns of primary beam non-redundancy in close-packed 21 cm array observations
(Oxford University Press, 2021)Radio interferometer arrays such as HERA consist of many close-packed dishes arranged in a regular pattern, giving rise to a large number of ‘redundant’ baselines with the same length and orientation. Since identical ... -
Probing reionization with LOFAR (Low Frequency Array) using 21-cm redshift space distortions
(Oxford University Press, 2013)One of the most promising ways to study the epoch of reionization (EoR) is through radio observations of the redshifted 21-cm line emission from neutral hydrogen. These observations are complicated by the fact that the ... -
Validation of the HERA Phase I Epoch of Reionization 21 cm Power Spectrum Software Pipeline
(The American Astronomical Society., 2022)We describe the validation of the HERA Phase I software pipeline by a series of modular tests, building up to an end-to-end simulation. The philosophy of this approach is to validate the software and algorithms used in ... -
Validation of the hera phase i epoch of reionization 21 cm power spectrum software pipeline
(IOP Publishing, 2022)We describe the validation of the HERA Phase I software pipeline by a series of modular tests, building up to an end-to-end simulation. The philosophy of this approach is to validate the software and algorithms used in ...