Mysterious Monster star-making galaxy has been discovered

Astronomers have discovered a mysterious “monster galaxy”, which existed during the universe’s infancy around 12 billion years ago.

The galaxy has been named XMM-2599, and what makes it so unique is it was a star-making machine, that just stopped. In its prime, this intriguing galaxy birthed over 1000 suns per year, a staggering amount when we consider the Milky Way creates roughly one in the same time frame.

The three panels show, from top to bottom, what XMM-2599’s evolutionary trajectory might be, beginning as a dusty star-forming galaxy, then becoming a dead galaxy, and perhaps ending up as a “brightest cluster galaxy,” or BCG. (NRAO/AUI/NSF/B. Saxton; NASA/ESA/R. Foley; NASA/StScI) – image via

The team which is headed by scientists from the University of California, Riverside, is puzzled as to why XMM-2599 just died.  A postdoctoral researcher in the UC Riverside Department of Physics and Astronomy and the study’s lead author, Benjamin Forrest, explains the baffling situation, “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.”

Scientists utilized spectroscopic observational tools at the W. M. Keck Observatory in Hawaii, to measure and calculate the galaxy’s distance, and have been allocated additional time at the observatory to try to unravel more details surrounding the mystery.

 A Professor of Physics and Astronomy at UCR, Gillian Wilson, goes onto explain, “Even though such massive galaxies are incredibly rare at this epoch, the models do predict them. The predicted galaxies, however, are expected to be actively forming stars. What makes XMM-2599 so interesting, unusual, and surprising is that it is no longer forming stars, perhaps because it stopped getting fuel or its black hole began to turn on. Our results call for changes in how models turn off star formation in early galaxies.”

Wilson continues, “We have caught XMM-2599 in its inactive phase. We do not know what it will turn into by the present day. We know it cannot lose mass. An interesting question is what happens around it. As time goes by, could it gravitationally attract nearby star-forming galaxies and become a bright city of galaxies?”

 An Associate Professor of Astronomy at UC Irvine, Michael Cooper, agrees with Wilson, adding, “Perhaps during the following 11.7 billion years of cosmic history, XMM-2599 will become the central member of one of the brightest and most massive clusters of galaxies in the local universe,” he said. “Alternatively, it could continue to exist in isolation. Or we could have a scenario that lies between these two outcomes.”

The results of the study have also been published in the Astrophysical Journal.