A Detection of Cosmological 21 cm Emission from CHIME in Cross-correlation with the eBOSS Lyman-alpha Forest

Event Date:
2023-06-01T13:00:00
2023-06-01T16:00:00
Event Location:
HENN 302
Speaker:
Tristan Pinsonneault-Marotte (PhD student)
Related Upcoming Events:
Intended Audience:
Public
Event 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.

Add to Calendar 2023-06-01T13:00:00 2023-06-01T16:00:00 A Detection of Cosmological 21 cm Emission from CHIME in Cross-correlation with the eBOSS Lyman-alpha Forest Event 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 $0.8&lt;z&lt;2.5$, 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 ($1.8 &lt; z &lt; 2.5$) 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