Kavli Affiliate: Jacqueline N. Hewitt
| First 5 Authors: , , , ,
| Summary:
Measuring one-point statistics in redshifted 21 cm intensity maps offers an
opportunity to explore non-Gaussian features of the early universe. We assess
the impact of instrumental effects on measurements made with the Hydrogen Epoch
of Reionization Array (HERA) by forward modeling observational and simulation
data. Using HERA Phase I observations over 94 nights, we examine the second
(m2, variance) and third (m3) moments of images. We employ the DAYENU-filtering
method for foreground removal and reduce simulated foreground residuals to 10%
of the 21 cm signal residuals. In noiseless cosmological simulations, the
amplitudes of one-point statistics measurements are significantly reduced by
the instrument response and further reduced by wedge-filtering. Analyses with
wedge-filtered observational data, along with expected noise simulations, show
that systematics alter the probability distribution of the map pixels.
Likelihood analysis based on the observational data shows m2 measurements
disfavor the cold reionization model characterized by inefficient X-ray
heating, in line with other power spectra measurements. Small signals in m3 due
to the instrument response of the Phase I observation and wedge-filtering make
it challenging to use these non-Gaussian statistics to explore model
parameters. Forecasts with the full HERA array predict high signal-to-noise
ratios for m2, m3, and S3 assuming no foregrounds, but wedge-filtering
drastically reduces these ratios. This work demonstrates conclusively that a
comprehensive understanding of instrumental effects on m2 and m3 is essential
for their use as a cosmological probe, given their dependence on the underlying
model.
| Search Query: ArXiv Query: search_query=au:”Jacqueline N. Hewitt”&id_list=&start=0&max_results=3