Extreme Star Factory: ALMA Detects Galaxy Y1 Forming Stars 180 Times Faster Than the Milky Way

By measuring the temperature of a distant galaxy with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope, astronomers have discovered an extreme star factory. The galaxy was Y1, and it lived between 600 and 800 million years after the Big Bang. The team headed by Tom Bakx of Chalmers University of Technology in Sweden discovered that Y1 is forming stars at approximately 180 solar masses per year, which is approximately 180 times the rate at which the Milky Way forms its stars. This is one way that the galaxies have become this fast in the young universe.

A superheated star factory

According to the paper, using ALMA's Band 9 (0.44 mm) and its array of 66 radio antennas, the Chalmers-led team captured Y1's dust emission, finding it shining at ~90 K (~–180 °C). Astronomer Yoichi Tamura says this warm dust confirms Y1 as “an extreme star factory”. The galaxy's star-formation rate is over 180 M☉ per year (versus ~1 M☉ in the Milky Way) – an unsustainably intense burst. Y1 (also called MACS0416_Y1) lies at redshift ≈8.3. Such brief, hidden bursts may have been common in the early universe.

Starbursts across the early cosmos

This picture is supported by other observations. As an example, Webb images discovered approximately 83 small starburst galaxies at a time of 800 million years following the Big Bang. According to NASA, these are the galaxies that are tiny yet powerful enough to cause cosmic reionisation as observed by Isak Wold. Similarly, ALMA/JWST observations discovered a barred spiral (J0107a) that was approximately 10 times the Milky Way in mass, and was capable of forming stars at a rate of approximately 300x. These findings have the suggestion that the starbursts that were hidden were an essential part of the early universe.