With every generation of telescopes, we are getting a better idea of what the young universe looked like and the latest observation from the Atacama Large Millimeter/submillimeter Array (ALMA) has thrown quite a curve ball.
By studying two early universe Milky Way-like galaxies, astronomers have discovered the progenitors of giant spiral galaxies were embedded in huge “super halos” of hydrogen gas. The material in these halos is believed to be building blocks for the hundred billion of stars that will eventually form in these galaxies. These observations are reported in Science.
"ALMA has solved a decades-old question on galaxy formation," co-author Chris Carilli, an astronomer with the National Radio Astronomy Observatory, said in a statement. "We now know that at least some very early galaxies have halos that are much more extended than previously considered, which may represent the future material for galaxy growth."
The international team of researchers observed the Milky Way-like galaxies from when the universe was just over a billion years old. The study of these was not an easy task. The galaxies were discovered using even more distant quasars, which are exceptionally bright galaxies. The light of the quasar can show the presence of a foreground galaxy but usually, we can’t learn much more than that. Luckily ALMA seems to be able to overcome this.
"Imagine a tiny firefly next to a high-power searchlight. That's what astronomers are up against when it comes to observing these youthful versions of our home galaxy," added lead author Marcel Neeleman a postdoctoral fellow at the University of California, Santa Cruz. "We can now see the galaxies themselves, which gives us an amazing opportunity to learn about the earliest history of our own galaxy and others like it."
ALMA looks at the infrared and microwave universe, which allows it to capture hard-to-see distant and dim objects, such as these galaxies.
Researchers are now planning to expand this search and are aiming to observe a large number of early galaxies over the next few years. The mysteries of these objects are living on borrowed time.