Chilean astronomer leads new scientific discoveries in a colossal galaxy

“Surprisingly, although we know that Malin 1 has young stars, to date no molecular gas emission has been detected by tracers such as carbon monoxide (CO), which is typically used to identify the distribution of molecular gas in galaxies,” explains Galaz, who has been studying the Malin 1 galaxy for years.

Located more than a billion light-years from the Milky Way, Malin 1 is almost seven times larger than our home galaxy with a diameter of about 650,000 light-years. Malin 1 was discovered in 1986 by a team of renowned astronomers of that time, including astronomer David Malin, hence its name. It is the first of a type of galaxy that has been called a “low surface brightness giant spiral galaxy.” “They are not very common and to date it is unknown how many like them exist. However, computational simulations indicate that there should be many more, and we should in the future detect several hundred more of them,” says Galaz, who also holds a PhD in Astrophysics from the University of Paris.

Who took my gas?

“We think that the molecular gas is there. It must be, because as we know Malin 1 even contains young stars,” says Gaspar Galaz. The new research posits that such gas could be found under different physical conditions than most spiral galaxies. “In particular, we think it is hotter, and therefore the CO molecular emission line that has been traditionally used, and in this study as well, is perhaps not the most suitable for tracing molecular gas in this type of galaxy. Another possibility would be that the molecular gas is effectively at such an extraordinarily low density that star formation has definitely ceased, except in some very specific places in the galaxy, where it is colder and denser”, adds the UC-CATA astronomer.

To achieve these results, more than 17 hours of observing time were necessary, carried out between 2018 and 2019, using the Byrd radio telescope of 100 meters in diameter, with the instrument that detects submillimeter radiation ARGUS.  The Byrd radio telescope is located in Green Bank, West Virginia, USA.

It is hoped to learn more about this galaxy in future studies by targeting specific locations in Malin 1 with the ALMA radio telescope, and possibly also using other molecules that trace the molecular gas. “We also know from recent observations of ours with the VLT/MUSE (an optical instrument), that this galaxy has ionized atomic hydrogen emission in some places where stars have formed recently,” Galaz concludes.

To see the link to the original research published in the Astrophysical Journal Letters, click here.