Elusive Dark Galaxy Revealed By ALMA Telescope Observations: Report

The "Invisible Galaxy," a black galaxy that has previously eluded our most advanced telescopes, has been found by researchers. Even the most cutting-edge instruments were unable to detect the extremely faraway item.

In a recent study presented in The Astrophysical Journal, a team from SISSA has fully characterised its properties. Using the Atacama Large Millimeter/Submillimeter Array (ALMA), the team revealed that it is "compact, and containing large quantities of interstellar dust, it is a young galaxy, forming stars at about 1000 times the rate of the Milky Way."

A research team led by astrophysics doctoral student Marika Giulietti of the Scuola Internazionale Superiore di Studi Avanzati (Sissa) in Italy described it as "so dark that it is almost invisible, even to highly sophisticated instruments."

"Very distant galaxies are real mines of information about the past and future evolution of our universe," explains Marika Giulietti.

"However, studying them is very challenging. They are very compact and therefore difficult to observe. Also, because of the distance, we receive very weak light from them. The cause of this obscuration is the massive presence of interstellar dust, which intercepts visible light from young stars, makes it difficult to detect with optical instruments, and re-emits it at greater wavelengths where it can be observed only with powerful interferometers in the (sub-)millimeter and radio wavebands."

Giulietti continues: "In this way, large celestial bodies act as a kind of enormous cosmic lens that makes the 'background' galaxies appear larger and brighter, allowing them to be identified and studied." Over the past decade, many observation programmes have been carried out with this approach. "About a hundred have been discovered so far, but there could be many more."

The Big Bang, which is thought to have happened around 13.8 billion years ago, actually happened only 2 billion years before the galaxy.