For the first time, scientists have used Earth-based telescopes to peer back into the cosmic dawn — an era more than 13 billion years ago when light from the first stars began reshaping our universe.
“Astronomy is a technology-limited field, and microwave signals from the Cosmic Dawn are famously difficult to measure.
The telescope, which obtained its first light in 2016, is tuned to survey the sky at microwave frequencies.
Besides enabling it to map 75% of the night sky, the telescope’s unprecedented sensitivity lets it receive microwave signals from the cosmic dawn, or the first billion years of the universe’s life.
To arrive at these observations, the researchers compared CLASS telescope data with that from the Planck and WMAP missions, narrowing down a common signal for the polarized microwave light.
When light from the first stars started to reshape our universe more than 13 billion years ago, scientists used Earth-based telescopes to look back into the cosmic dawn for the first time.
The remaining light from this ancient period is millimeters in wavelength and very faint, so even though space-based observatories have been able to see into it, the signal is lost in Earth’s atmosphere’s electromagnetic radiation before ground-based telescopes can pick up the primordial light.
However, using a specially built telescope, researchers at the Cosmology Large Angular Scale Surveyor (CLASS) project have now found evidence of the first stars’ impact on the Big Bang’s background light. Their results were published in The Astrophysical Journal on June 11.
Tobias Marriage, the CLASS project leader and a professor of physics and astronomy at Johns Hopkins University, co-authored the study and said in a statement, “People thought this couldn’t be done from the ground.”. “Microbe signals from the Cosmic Dawn are notoriously hard to measure, and astronomy is a field with limited technological capabilities. There are more difficulties with ground-based observations than with space-based ones. By overcoming those challenges, this measurement represents a noteworthy accomplishment. “.”.
The CLASS observatory is located in the Andes mountains of the Atacama desert in northern Chile, at a height of 16,860 feet (5,138 meters). The telescope is set up to scan the sky at microwave frequencies; it received its first light in 2016. Its unparalleled sensitivity allows the telescope to receive microwave signals from the cosmic dawn, or the first billion years of the universe’s existence, in addition to mapping seventy-five percent of the night sky.
Light could not pass through the universe’s dense electron cloud during the first 380,000 years following the Big Bang. Protons eventually absorbed the electrons to create hydrogen atoms as our universe cooled and expanded.
Related: The first-ever merging galaxy cores are found by astronomers at cosmic dawn.
The cosmic microwave background (CMB) is made up of the free movement of microwave-wavelength light made possible by these hydrogen atoms. In areas where the light was sufficiently dense, it also collapsed under gravity and ignited to form the first stars. After that, the light from these stars reionized pockets of unclumped hydrogen gas, separating their electrons. Some of these electrons then collided with the CMB’s light, polarizing it.
Our understanding of the early universe would be unclear without the signal from this polarized region of the CMB, which is an essential piece of the cosmological puzzle.
Additionally, while previous space-based telescopes have attempted to bridge this gap, including the European Space Agency’s Planck space telescope and NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), their images contain noise and, because they are satellites, cannot be adjusted or enhanced once in orbit.
“Measuring this reionization signal more precisely is an important frontier of cosmic microwave background research,” Co-author Charles Bennett, who led the WMAP space mission and is a professor of physics at Johns Hopkins, said in the statement.
The scientists narrowed down a common signal for the polarized microwave light by comparing data from the Planck and WMAP missions with that from the CLASS telescope to arrive at these observations.
“The universe is like a physics lab to us. “Our understanding of dark matter and neutrinos, which are abundant but elusive particles that fill the universe, is improved by better measurements of the universe,” Bennett continued. In the future, we intend to analyze more CLASS data in an effort to achieve the highest level of precision. “.”.
