Probing the Cosmic Dawn and Epoch of Re-ionization with REACH
Lead Research Organisation:
University of Cambridge
Department Name: Physics
Abstract
The Big Bang model for the origin and initial evolution of the Universe is by now a familiar and well-studied research field. The subsequent, late time, evolution of stars and other celestial objects over billions of years is perhaps even better understood. Less is known, however, about the time between these periods (from about 0.35 to 1 billion years after the Big Bang). During this time the Universe transitioned from being a vast volume filled with a cooling neutral gas to become the realm of cosmic objects that we can now observe from Earth.
At the beginning the Universe was filled with a hot, dense fog of ionized gas until the continued expansion and cooling allowed electrons and protons to combine and form the first neutral atoms, eg. hydrogen. Eventually, the neutral matter clumped together under the effects of gravity, providing the conditions for nuclear fusion to occur, leading to the birth of the first stars and galaxies (period known as the Cosmic Dawn). Subsequently, these objects heated and re-ionised the surrounding hydrogen in the Universe during the Epoch of Re-ionization.
Researchers speculate that electromagnetic signals from those times should be detectable from Earth at frequencies around the FM band and could be used to study the early Universe. Our best estimations indicate that by using a single antenna radio telescope we should be able to detect the elusive radio waves from this period. However, this will require, as a minimum, calibrating the response of the radio receiver to unprecedented levels. Using my experience designing radio sensors for the super telescope Square Kilometre Array and the Hydrogen Epoch of Re-ionization Array, I will focus my work on developing and operating a simple, very stable, easily calibratable sensor of electromagnetic waves capable of detecting these extremely faint theorized signals if operated from a remote radio quiet zone such as desert areas far away from human-made radio signals and interference.
This experiment is called REACH (Radio Experiment for the Analysis of Cosmic Hydrogen), and it will aim at opening a window to these early epochs of the Universe by observing radio signals naturally emitted by hydrogen from the semi-desertic region of the Karoo in South Africa. Hydrogen was the raw material forming the very first stars but also these same hydrogen clouds filling the Universe at the time stop us from directly observing the light from these first stars. Thus, we aim to look at these stars through their interaction with the hydrogen clouds in the same way one would infer a landscape by looking at the shadows in the fog covering it.
At the beginning the Universe was filled with a hot, dense fog of ionized gas until the continued expansion and cooling allowed electrons and protons to combine and form the first neutral atoms, eg. hydrogen. Eventually, the neutral matter clumped together under the effects of gravity, providing the conditions for nuclear fusion to occur, leading to the birth of the first stars and galaxies (period known as the Cosmic Dawn). Subsequently, these objects heated and re-ionised the surrounding hydrogen in the Universe during the Epoch of Re-ionization.
Researchers speculate that electromagnetic signals from those times should be detectable from Earth at frequencies around the FM band and could be used to study the early Universe. Our best estimations indicate that by using a single antenna radio telescope we should be able to detect the elusive radio waves from this period. However, this will require, as a minimum, calibrating the response of the radio receiver to unprecedented levels. Using my experience designing radio sensors for the super telescope Square Kilometre Array and the Hydrogen Epoch of Re-ionization Array, I will focus my work on developing and operating a simple, very stable, easily calibratable sensor of electromagnetic waves capable of detecting these extremely faint theorized signals if operated from a remote radio quiet zone such as desert areas far away from human-made radio signals and interference.
This experiment is called REACH (Radio Experiment for the Analysis of Cosmic Hydrogen), and it will aim at opening a window to these early epochs of the Universe by observing radio signals naturally emitted by hydrogen from the semi-desertic region of the Karoo in South Africa. Hydrogen was the raw material forming the very first stars but also these same hydrogen clouds filling the Universe at the time stop us from directly observing the light from these first stars. Thus, we aim to look at these stars through their interaction with the hydrogen clouds in the same way one would infer a landscape by looking at the shadows in the fog covering it.
People |
ORCID iD |
Eloy De Lera Acedo (Principal Investigator / Fellow) |
Publications
Anstey D
(2023)
Use of time dependent data in Bayesian global 21-cm foreground and signal modelling
in Monthly Notices of the Royal Astronomical Society
Anstey D
(2022)
Informing antenna design for sky-averaged 21-cm experiments using a simulated Bayesian data analysis pipeline
in Monthly Notices of the Royal Astronomical Society
Bevins H
(2022)
A comprehensive Bayesian reanalysis of the SARAS2 data from the epoch of reionization
in Monthly Notices of the Royal Astronomical Society
Cumner J
(2022)
Radio Antenna Design for Sky-Averaged 21cm Cosmology Experiments: The REACH Case
in Journal of Astronomical Instrumentation
De Lera Acedo E
(2022)
The REACH radiometer for detecting the 21-cm hydrogen signal from redshift z ˜ 7.5-28
in Nature Astronomy
De Lera Acedo E
(2022)
Author Correction: The REACH radiometer for detecting the 21-cm hydrogen signal from redshift z ˜ 7.5-28
in Nature Astronomy
Josaitis A
(2022)
Array element coupling in radio interferometry I: a semi-analytic approach
in Monthly Notices of the Royal Astronomical Society
Kirkham C
(2024)
A Bayesian method to mitigate the effects of unmodelled time-varying systematics for 21-cm cosmology experiments
in Monthly Notices of the Royal Astronomical Society
Scheutwinkel K
(2022)
Bayesian evidence-driven diagnosis of instrumental systematics for sky-averaged 21-cm cosmology experiments
in Publications of the Astronomical Society of Australia