The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a radio telescope that we built to map the large-scale structure of the Universe between redshifts $0.8<z<2.5$, when dark energy is expected to begin the transition from a decelerating to an accelerating phase in its expansion. It was designed to perform an intensity mapping survey using the 21 cm line of neutral hydrogen, a novel method that has the potential to enable enormous surveys of the distant Universe, but also significant observational challenges to overcome.
I will describe how CHIME operates, and highlight some of my contributions to its data acquisition system and calibration effort, culminating in a detection of cosmological 21 cm emission in cross-correlation with measurements of the Lyman-alpha forest, at an average redshift $\bar{z} = 2.3$. Data collected by CHIME over 88 days in the 400-500~MHz frequency band ($1.8 < z < 2.5$) were formed into maps of the sky and high-pass delay filtered to suppress the foreground power. Line-of-sight spectra to the eBOSS background quasar locations were extracted from the CHIME maps and combined with the Lyman-alpha forest flux transmission spectra to estimate the 21 cm-Lyman-alpha cross-correlation function. Fitting a simulations-derived template to this measurement results in a $9\sigma$ detection significance.
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2023-06-01T13:00:002023-06-01T16:00:00A Detection of Cosmological 21 cm Emission from CHIME in Cross-correlation with the eBOSS Lyman-alpha ForestEvent Information:
Abstract:
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a radio telescope that we built to map the large-scale structure of the Universe between redshifts $0.8<z<2.5$, when dark energy is expected to begin the transition from a decelerating to an accelerating phase in its expansion. It was designed to perform an intensity mapping survey using the 21 cm line of neutral hydrogen, a novel method that has the potential to enable enormous surveys of the distant Universe, but also significant observational challenges to overcome.
I will describe how CHIME operates, and highlight some of my contributions to its data acquisition system and calibration effort, culminating in a detection of cosmological 21 cm emission in cross-correlation with measurements of the Lyman-alpha forest, at an average redshift $\bar{z} = 2.3$. Data collected by CHIME over 88 days in the 400-500~MHz frequency band ($1.8 < z < 2.5$) were formed into maps of the sky and high-pass delay filtered to suppress the foreground power. Line-of-sight spectra to the eBOSS background quasar locations were extracted from the CHIME maps and combined with the Lyman-alpha forest flux transmission spectra to estimate the 21 cm-Lyman-alpha cross-correlation function. Fitting a simulations-derived template to this measurement results in a $9\sigma$ detection significance.Event Location:
HENN 302