An ultra-large galaxy called XMM-2599 is leaving astronomers across the world puzzled. This vast monster galaxy, that was teeming with star formation stopped producing more stars all of a sudden and no one knows why.
Scientists estimate that this galaxy existed about 12 billion years ago, during the early days of the universe when it was only around 1.8 billion years old. The study conducted on the stars expresses that the galaxy could even challenge our existing models of the early universe.
Benjamin Forest, the lead author of the study says that “even before the universe was 2 billion years old, XMM-2599 had already formed a mass of more than 300 billion suns, making it an ultra massive galaxy. More remarkably, we show that XMM-2599 formed most of its stars in a huge frenzy when the universe was less than 1 billion years old, and then became inactive by the time the universe was only 1.8 billion years old.”
The question of how this galaxy came into being and how it stopped existing suddenly is perplexing the astronomers. The team believes that further study of the universe could dramatically change our understanding of how stars form and stop forming.
Gillian Wilson, a professor of physics and astronomy at the University of California says that only a few galaxies in the epoch that hosts the XMM-2599 have stopped forming stars. But none of them is as massive as the XMM galaxy.
It is interesting to note that our current models of the universe do predict the existence of massive galaxies such as XMM, but they are all expected by the model to be active. This is what makes the case of XMM extremely mysterious. At its peak, the galaxy was forming stars equivalent to or more than 1000 of suns each year. That’s an incredible rate of star formation as our Milkyway galaxy only forms one star per year.
The galaxy from this active state of frenzy has come to a grinding halt. The galaxy is so far away that actually we are looking at its past now. It means the galaxy might look completely different right now from what we are seeing.
“We have caught XMM-2599 in its inactive phase. We do not know what it will turn into by the present day,” says Wilson.
The team behind the discovery of XMM is hoping to gain more insight into the galaxy by using the high tech equipment present in Keck Observatory. They believe they will be able to understand how monster galaxies form and die by conducting further observations on this galaxy.