ALMA | NRAO | NAOJ | ESO | 2018 Sep 06
ALMA observes most distant galactic outflow
Astronomers using ALMA, with the aid of a gravitational lens, have detected the most distant galactic “wind” of molecules ever observed, seen when the universe was only one billion years old. By tracing the outflow of hydroxyl (OH) molecules -- which herald the presence of star-forming gas in galaxies -- the researchers show how some galaxies in the early universe quenched an ongoing wildfire of starbirth.
- ALMA, aided by a gravitational lens, imaged the outflow, or 'wind,' from a galaxy seen when the universe was only one billion years old. The ALMA image (circle call out) shows the location of hydroxyl (OH) molecules. These molecules trace the location of star-forming gas as it is fleeing the galaxy, driven by either supernovas or a black-hole powered 'wind.' The background star field (Blanco Telescope Dark Energy Survey) shows the location of the galaxy. The circular, double-lobe shape of the distant galaxy is due to the distortion caused by the cosmic magnifying effect of an intervening galaxy. (Credit: ALMA (ESO/NAOJ/NRAO), Spilker; NRAO/AUI/NSF, S. Dagnello; AURA/NSF)
Some galaxies, like the Milky Way and Andromeda, have relativelyslow and measured rates of starbirth, with about one new star igniting each year. Other galaxies, known as starburst galaxies, forge 100s or even 1000s of stars each year. This furious pace, however, cannot be maintained indefinitely.
To avoid burning out in a short-lived blaze of glory, some galaxies throttle back their runaway starbirth by ejecting, at least temporarily, vast stores of gas into their expansive halos, where the gas either escapes entirely or slowly rains back in on the galaxy, triggering future bursts of star formation.
Up to now, however, astronomers have been unable to directly observe these powerful outflows in the very early universe, where such mechanisms are essential to prevent galaxies from growing too big, too fast.
New observations with the Atacama Large Millimeter/submillimeter Array (ALMA), show, for the first time,a powerfulgalactic “wind” of molecules in a galaxy seen when the universe was only one billion years old. This result provides insights into how certain galaxies in the early universe were able to self-regulate their growth,so they could continue forming stars across cosmic time. ...
Fast Molecular Outflow from a Dusty Star-Forming Galaxy in the Early Universe ~ J.S. Spilker et al
- Science 361(6406):1016 (07 Sep 2018) DOI: 10.1126/science.aap8900