Cosmic Lens Reveals Hyperactive Cradle of Future Galaxy Cluster
Astronomers have gained an unprecedented view into the early stages of galaxy cluster formation, peering back over 11 billion years using a natural gravitational lens. This discovery, made possible by the combined power of the Particularly Large Array and the Atacama Large Millimeter/submillimeter Array (ALMA), reveals a protocluster core brimming with star-forming galaxies.
Unveiling J0846: A Protocluster in the Early Universe
The object, designated J0846, is a protocluster – an early stage galaxy cluster where gravity is actively assembling what will eventually grow a massive structure in the universe. What makes J0846 unique is its alignment with a closer galaxy cluster, which acts as a gravitational lens, magnifying and brightening the light from the distant protocluster. This effect allows astronomers to observe details that would otherwise be impossible to discern.
A Magnified View of Starburst Galaxies
Previously appearing as a single smudge of light, the magnified view revealed at least eleven separate galaxies crammed into a region smaller than the distance between the Milky Way and the Andromeda Galaxy. Each of these galaxies is undergoing a “starburst,” a period of intense star formation, producing stars at a rate far exceeding that of our own galaxy. These galaxies are heavily obscured by dust, which blocks visible light, but ALMA’s ability to detect faint emissions from cold dust and gas allows astronomers to penetrate this cosmic fog.
Peering Back in Time
Nicholas Foo, a graduate student at Arizona State University, likened the observation to archaeological excavation, with the foreground cluster representing a modern city and the protocluster its ancient origins. By looking further back in space, astronomers are effectively looking back in time, and in this case, they are observing a galaxy cluster in its earliest stages of development – more than eleven billion years ago. What was once a faint smudge has become one of the most extraordinary objects in the early universe.
The Power of ALMA and Gravitational Lensing
The Atacama Large Millimeter/submillimeter Array (ALMA) played a crucial role in this discovery by detecting the faint glow of cold dust and gas, revealing the raw materials fueling the intense star formation. Combined with the natural magnification provided by the gravitational lens, ALMA has provided astronomers with an unparalleled opportunity to study the conditions in which galaxy clusters first began to form. Space.com reports on the significance of this discovery.
According to the European Southern Observatory, this research represents a significant step forward in understanding the evolution of galaxy clusters.
SciTechDaily highlights that this is the largest ALMA image ever obtained.
The ALMA Observatory also released a press release detailing the discovery.