Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have spotted the light of a massive galaxy seen only 970 million years after the Big Bang.
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have spotted the light of a massive galaxy seen only 970 million years after the Big Bang. This galaxy, called MAMBO-9, is the most distant dusty star-forming galaxy that has ever been observed without the help of a gravitational lens.
Dusty star-forming galaxies are the most intense stellar nurseries in the universe. They form stars at a rate up to a few thousand times the mass of the Sun per year (the star-forming rate of our Milky Way is just three solar masses per year) and they contain massive amounts of gas and dust. Such monster galaxies are not expected to have formed early in the history of the universe, but astronomers have already discovered several of them as seen when the cosmos was less than a billion years old. One of them is galaxy SPT0311-58, which ALMA observed in 2018.
Because of their extreme behavior, astronomers think that these dusty galaxies play an important role in the evolution of the universe. But finding them is easier said than done. “These galaxies tend to hide in plain sight,” said Caitlin Casey of the University of Texas at Austin and lead author of a study published in The Astrophysical Journal. “We know they are out there, but they are not easy to find because their starlight is hidden in clouds of dust.”
MAMBO-9’s light was already detected ten years ago by co-author Manuel Aravena, using the Max-Planck Millimeter BOlometer (MAMBO) instrument on the IRAM 30-meter telescope in Spain and the Plateau de Bure Interferometer in France. But these observations were not sensitive enough to reveal the distance of the galaxy. “We were in doubt if it was real, because we couldn’t find it with other telescopes. But if it was real, it had to be very far away,” says Aravena, who was at that time a PhD student in Germany and is currently working for the Universidad Diego Portales in Chile.
Read more at National Radio Astronomy Observatory
Image: ALMA radio image of the dusty star-forming galaxy called MAMBO-9. The galaxy consists of two parts, and it is in the process of merging. (Credit: ALMA (ESO/NAOJ/NRAO), C.M. Casey et al.; NRAO/AUI/NSF, B. Saxton)
