Astronomers have developed a new way to “see” through the fog of the early universe to detect light from the very first stars and galaxies.
Observing the birth of these objects has long been a goal of scientists because it will help explain how the universe evolved from the void after the Big Bang to the complex cosmos we see today, 13.8 billion years later.
That’s what the new James Webb Space Telescope is doing, as well as the Square Kilometer Array (SKA).
But while Webb is studying infrared wavelengths, the next-generation SKA ground-based telescope, due to be completed by the end of the decade, will study the early universe using radio waves.
For modern radio telescopes, the challenge is to detect the cosmological signal of stars through thick hydrogen clouds, which block the view because they absorb light very well.
Distortion from other radio signals can also interfere, which is considered one of the extreme problems facing modern radio cosmology.
For example, the signals from distant galaxies that astronomers try to detect are about 100,000 times weaker than the signals from our own galaxy.
But researchers at the University of Cambridge have now developed a new methodology using mathematics that will allow them to see through primary clouds and other noisy sky signals.
Birth of the Cosmos: Astronomers have developed a new way to “see” through the fog of the early universe so they can detect light from the very first stars and galaxies. This artist’s impression depicts the appearance of stars in the early universe.
Their idea, which was part of the REACH experiment in South Africa (pictured), will allow scientists to observe early stars through their interactions with light-blocking hydrogen clouds.
Thus, this will allow them to avoid the harmful effects of distortions introduced by the radio telescope.
Their idea, which was part of the REACH (Radio Space Hydrogen Analysis) experiment, will allow astronomers to observe the earliest stars through their interactions with hydrogen clouds, just like we infer landscapes by looking at shadows. in the fog.
It is hoped that this will improve the quality and reliability of observations by radio telescopes studying this unexplored pivotal moment in the evolution of the universe.
The first REACH sightings are expected later this year.
“At the time the first stars formed, the universe was mostly empty and consisted mostly of hydrogen and helium,” said study lead author Dr Eloy de Lera Acedo of the Cambridge Cavendish Laboratory.
He added: “Due to gravity, the elements eventually combined and the conditions were right for the nuclear fusion that formed the first stars.
“But they were surrounded by clouds of so-called neutral hydrogen, which absorb light very well, so it’s hard to detect or observe light directly behind the clouds.”
In 2018, another research team published a result that hinted at the possible detection of this earliest light, but astronomers were unable to replicate it, leading them to believe that the original result could be due to interference from the telescope being used.
“The initial result would require an explanation of new physics due to the temperature of hydrogen gas, which must be much lower than our current understanding of the universe allows,” said Dr. de Lera Acedo.
Pictured is an aerial view of the observation site at the REACH Karoo Radio Conservation Area, South Africa.
The Square Kilometer Array telescope (pictured) is designed to study the evolution of the early universe when it becomes operational later this decade. He will study it with radio waves.
“Alternatively, the cause could be an unexplained higher temperature of the background radiation – usually assumed to be the well-known cosmic microwave background.”
He added: “If we can confirm that the signal found in this earlier experiment did indeed come from the first stars, the implications would be enormous.”
To study this period in the evolution of the Universe, often referred to as the Cosmic Dawn, astronomers use the 21-centimeter line, the signature of electromagnetic radiation from hydrogen in the early Universe.
They are looking for a radio signal that measures the contrast between the hydrogen emission and the emission behind the hydrogen fog.
The methodology developed by Dr. de Lera Acedo and colleagues uses Bayesian statistics to detect a cosmological signal in the presence of interference from a telescope and general noise from the sky so that the signals can be separated.
The new James Webb Space Telescope is also tasked with doing this, but it looks at wavelengths in the infrared.
This required the most modern techniques and technologies from different fields.
Construction of the SKA telescope is currently being completed at the Karoo Radio Conservation Area in South Africa, a site chosen for its excellent conditions for radio observations of the sky.
It is far away from man-made radio frequency interference such as TV and FM radio signals.
The big bang and the very early periods of the universe are well understood through studies of the cosmic microwave background (CMB) radiation.
But the timing of the formation of the first light in space is a fundamental missing piece in the puzzle of the history of the universe.
New study published in the journal Astronomy of nature.
SKA WILL BE THE LARGEST RADIO TELESCOPE IN THE WORLD
The Square Kilometer Array (SKA), a joint project between Australia and South Africa, will be the world’s largest radio telescope.
More sensitive than any modern radio telescope, it will allow scientists to study the universe in more detail than ever before.
The telescope will be located in South Africa and Australia, with international headquarters at Jodrell Bank in the UK.
Almost 200 mid-range dishes (including the existing MeerKAT installation, which was officially launched in July 2018) will be located in the Karoo region of South Africa.
Artist’s impression of the 3-mile (5 km) diameter Square Kilometer Array (SKA) central core antennas
Approximately 130,000 low frequency antennas will be located in Western Australia.
Both sites are far from sources of radio interference, which allows for very sensitive measurements.
SKA will consist of two instruments: SKA-mid (dishes) and SKA-low (antennas).
The signals from the dishes will be transmitted over an optical fiber to a central computer, where they will be combined using a technique called interferometry.
Similarly, the signal from all the antennas will also be combined and converted into scientific data that astronomers will use to study the universe.
Source: UKRI
