Ancient 'monster galaxy' that formed stars in 'huge frenzy' dies mysteriously, scientists baffled

Named  XMM-2599, the galaxy hosted stars that formed at a high rate and then died. This has left astronomers puzzled as they are yet to understand the factors that led to its quick demise


                            Ancient 'monster galaxy' that formed stars in 'huge frenzy' dies mysteriously, scientists baffled
Spiral galaxy NGC 4414 as photographed by the Hubble Space Telescope (NASA)

The early universe was once home to a monster galaxy, against which even our Milky Way would pale in comparison. But not for too long -- the galaxy mysteriously went off, report scientists in a new study.

Named  XMM-2599, the galaxy hosted stars that formed at a high rate and then died. This has left astronomers puzzled, as they are yet to understand the factors that led to its quick demise. "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," Benjamin Forrest, lead study author and a postdoctoral researcher in the University of California, Riverside's Department of Physics and Astronomy, tells MEA WorldWide (MEAWW).

During that period, stars formed at a frenzied rate but they soon died out, when the universe was only 1.8 billion years old, according to Forrest. The team discovered the signs of its existence using W. M. Keck Observatory while looking at large amounts of data from a catalog of galaxies, capturing images in different colors.

"Based on those colors, this galaxy, in particular, stood out as likely being observed at a very early time in cosmic history," Forrest said. This suggested that this galaxy could be very massive and inactive. So the team carried out follow-up studies to confirm this hunch. 

This image set shows the possible evolution of XMM-2599, from a massive, dusty, star-forming galaxy (left), to an inactive red galaxy (center), and then perhaps turning into a bright cluster galaxy (right). (NRAO/AUI/NSF, B. SAXTON; NASA/ESA/R. FOLEY; NASA/ESA/STSCI, M. POSTMAN/CLASH)

The research team found that in its heydays, the galaxy formed more than 1,000 solar masses -- equal to the mass of 1,000 suns-- a year.  In contrast, the Milky Way forms about one new star a year.

Most galaxies,  unlike XMM-2599, continue to remain active. Only a few of them turn idle, meaning they stop 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," explains Dr. Gillian Wilson, a professor of physics and astronomy at UCR in whose lab Forrest works.

In the future, the team predicts that the galaxy could turn into bright, massive clusters of galaxies. There is also a possibility of it continuing to exist in isolation, the team adds. "This discovery forces us to reconsider our ideas of how massive galaxies in the early universe form, as well as what processes can cause a shut-off of star formation at such early times," explained Forrest. 

"Finding other similar galaxies and following them up with telescopes such as ALMA, HST, and JWST will help find the answers to these questions, which will help us better understand the lives and evolutions of galaxies," he added.

The study published today in the Astrophysical Journal.

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