The frontiers of astronomy are being pushed regularly these days thanks to next-generation telescopes and scientific collaborations. Even so, astronomers are still waiting to peel back the veil of the cosmic “Dark Ages,” which lasted from roughly 370,000 to 1 billion years after the Big Bang, where the Universe was shrouded with light-obscuring neutral hydrogen. The first stars and galaxies formed during this same period (ca. 100 to 500 million years), slowly dispelling the “darkness.” This period is known as the Epoch of Reionization, or as many astronomers call it: Cosmic Dawn.
By probing this period with advanced radio telescopes, astronomers will gain valuable insights into how the first galaxies formed and evolved. This is the purpose of the Hydrogen Epoch of Reionization Array (HERA), a radio telescope dedicated to observing the large-scale structure of the cosmos during and before the Epoch of Reionization located in the Karoo desert in South Africa. In a recent paper, the HERA Collaboration reports how it doubled the array’s sensitivity and how their observations will lead to the first 3D map of Cosmic Dawn.
The HERA Collaboration is an international consortium comprised of astronomers and astrophysicists from South Africa, Australia, the U.S., the U.K., Israel, Italy, and India. The research was led by Joshua Dillon, a research scientist at UC Berkeley’s Department of Astronomy and the lead author of the paper. The paper that describes their research and findings recently appeared online and has been accepted for publication by the Astrophysical Journal. Their results provide new insight into how reionization occurred in the early Universe.
A timeline of the cosmos showing which eras will be observed by the Planck satellite, HERA, and NASA’s JWST. Credit: HERA
From Dark to Dawn
Based on current cosmological models, the Universe began 13.8 billion years ago with the Big Bang, which produced a flurry of energy and elementary particles that slowly cooled to create the first protons and electrons (which combined to form the first hydrogen and helium atoms). The leftover “relic radiation” is observable today in the form of the Cosmic Microwave Background (CMB). Thanks to missions like the COBE, WMAP, and Planck, astronomers have mapped the faint variations in temperature that existed 380,000 years after the Big Bang.