The Hydrogen Epoch of Reionization Array (HERA) telescope has released its first set of observations to the world. Notably, the observations give a glimpse of what the universe looked like 13 billion years ago. HERA is an array of 350 antennas situate next to MeerKAT in the Northern Cape province of South Africa.
Interestingly, the telescope is still under construction. A team of four Carnarvon-based artisans began construction of the HERA telescope in early 2015. Construction of the array is in such a way that the constructors hook antennas into the telescope data correlation system as soon as they complete it. This is according to Kathryn Rosie, HERA Project Engineer at the time, and Matthys Maree, former construction supervisor. This unique feature enables users to carry out observations and early science while construction continues. After the initial construction, scientists carried out Phase I observations in 2017-2018 throughout the Southern Summer using about 50 dishes.
HERA is an array of 14-meter diameter dishes, packed closely together and pointing straight up at the sky. The constructors built the telescope using wooden poles, a PVC pipe structure and wire mesh. Furthermore, A US-led project, HERA is an extensive international collaboration, with a solid South African participation, from construction to science. Its purpose is to observe how the first structures formed in the very early stages of the universe.
The South African Radio Astronomy Observatory (SARAO), is responsible for providing the necessary construction management and systems engineering. Furthermore, SARAO is also providing location, power and fibre networks needed to operate the HERA instrument. The original building team in Phase I grew from four artisans to over 20 people. Currently, for Phase II, the building team comprises ten artisans.
Astronomers want to understand how the universe reached conditions for first stars and galaxies’ formation which HERA will help with. “Even the most powerful optical and infra-red space telescopes like the Hubble Space Telescope or its upcoming successor, the James Webb Space Telescope, won’t be able to look that far back in time. That is one of the reasons why radio astronomy is so important,” says Prof. Mario Santos, currently representing SARAO on the HERA board.
Scientists have published some scientific journal articles accompanying the Phase I data release. The scientists are from the University of the Western Cape, Rhodes University, the University of KwaZulu-Natal, and the international team. In addition, one of the papers presents the most sensitive upper limits to date on the strength of the signal we can detect from the universe at around 66 million years after the Big Bang. The lead scientist behind this paper, Dr Nicholas Kern, currently a postdoctoral fellow at MIT, says, “this analysis is a big step in demonstrating HERA’s unprecedented sensitivity going forward as construction is completed: with only a couple of weeks of data from the array at fractional capacity we are already producing world-leading limits”. A second paper further explains the implications of those upper limits for models of early universe star and galaxy formation.
Nearly six years after construction began, the array stands at a total of 332 dishes, with the remainder planned to finish in the coming weeks. “Commissioning and construction activities are progressing. We are currently conducting a logistic and support analysis to ensure smooth operations for the coming seasons to facilitate future discoveries,” adds current project engineer Ziyaad Halday.
“The upcoming observations with the enhanced HERA array should allow us to observe the lighting up of the very first stars after the Big Bang,” says Dr David DeBoer, HERA Project Manager, from the University of California, Berkeley.