Tag: Space and Astronomy

Astronomers discover unusual monster galaxy in the very early universe

Photo by Suzy Hazelwood on Pexels.com

An international team of astronomers led by scientists at the University of California, Riverside, has found an unusual monster galaxy that existed about 12 billion years ago, when the universe was only 1.8 billion years old.

Dubbed XMM-2599, the galaxy formed stars at a high rate and then died. Why it suddenly stopped forming stars is unclear.

“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 ultramassive galaxy,” said Benjamin Forrest, a postdoctoral researcher in the UC Riverside Department of Physics and Astronomy and the study’s lead author. “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 team used spectroscopic observations from the W. M. Keck Observatory‘s powerful Multi-Object Spectrograph for Infrared Exploration, or MOSFIRE, to make detailed measurements of XMM-2599 and precisely quantify its distance.

Study results appear in the Astrophysical Journal.

“In this epoch, very few galaxies have stopped forming stars, and none are as massive as XMM-2599,” said Gillian Wilson, a professor of physics and astronomy at UCR in whose lab Forrest works.  “The mere existence of ultramassive galaxies like XMM-2599 proves quite a challenge to numerical models. 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.”

The research team found XMM-2599 formed more than 1,000 solar masses a year in stars at its peak of activity — an extremely high rate of star formation. In contrast, the Milky Way forms about one new star a year.

“XMM-2599 may be a descendant of a population of highly star-forming dusty galaxies in the very early universe that new infrared telescopes have recently discovered,” said Danilo Marchesini, an associate professor of astronomy at Tufts University and a co-author on the study.

The evolutionary pathway of XMM-2599 is unclear.

“We have caught XMM-2599 in its inactive phase,” Wilson said. “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?”

Co-author Michael Cooper, a professor of astronomy at UC Irvine, said this outcome is a strong possibility.

“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 team has been awarded more time at the Keck Observatory to follow up on unanswered questions prompted by XMM-2599.

“We identified XMM-2599 as an interesting candidate with imaging alone,” said co-author Marianna Annunziatella, a postdoctoral researcher at Tufts University. “We used Keck to better characterize and confirm its nature and help us understand how monster galaxies form and die. MOSFIRE is one of the most efficient and effective instruments in the world for conducting this type of research.”

Black Hole Eats Star

Join Melissa Hoffman of the National Radio Astronomy Observatory for a tour of one of the most disruptive events in Universe.

What happens when a black hole has a star for dinner?

In this new video, Melissa Hoffman of the National Radio Astronomy Observatory takes us on a tour of one of the most disruptive events in Universe: a black hole ripping apart a nearby star.

Astronomers call these stellar deaths tidal disruption events, and only a few of them have been observed.

Using radio and infrared telescopes, including the National Science Foundation’s Very Long Baseline Array (VLBA), in 2018 an international team of astronomers witnessed this event in a pair of colliding galaxies called Arp 299.

Deep sea vents had ideal conditions for origin of life

Photo by Silas Baisch

By creating protocells in hot, alkaline seawater, a UCL-led research team has added to evidence that the origin of life could have been in deep-sea hydrothermal vents rather than shallow pools.

Previous experiments had failed to foster the formation of protocells – seen as a key stepping stone to the development of cell-based life – in such environments, but the new study, published in Nature Ecology & Evolution, finds that heat and alkalinity might not just be acceptable, but necessary to get life started.

“There are multiple competing theories as to where and how life started. Underwater hydrothermal vents are among most promising locations for life’s beginnings – our findings now add weight to that theory with solid experimental evidence,” said the study’s lead author, Professor Nick Lane (UCL Genetics, Evolution & Environment).

Deep under the Earth’s seas, there are vents where seawater comes into contact with minerals from the planet’s crust, reacting to create a warm, alkaline (high on the pH scale) environment containing hydrogen. The process creates mineral-rich chimneys with alkaline and acidic fluids, providing a source of energy that facilitates chemical reactions between hydrogen and carbon dioxide to form increasingly complex organic compounds.

Some of the world’s oldest fossils, discovered by a UCL-led team, originated in such underwater vents.

Scientists researching the origins of life have made great progress with experiments to recreate the early chemical processes in which basic cell formations would have developed. The creation of protocells has been an important step, as they can be seen as the most basic form of a cell, consisting of just a bilayer membrane around an aqueous solution – a cell with a defined boundary and inner compartment.

Previous experiments to create protocells from naturally-occurring simple molecules – specifically, fatty acids – have succeeded in cool, fresh water, but only under very tightly controlled conditions, whereas the protocells have fallen apart in experiments in hydrothermal vent environments.

The study’s first author, Dr Sean Jordan (UCL Genetics, Evolution & Environment), said he and his colleagues identified a flaw in the previous work: “Other experiments had all used a small number of molecule types, mostly with fatty acids of the same size, whereas in natural environments, you would expect to see a wider array of molecules.”

For the current study, the research team tried creating protocells with a mixture of different fatty acids and fatty alcohols that had not previously been used.

The researchers found that molecules with longer carbon chains needed heat in order to form themselves into a vesicle (protocell). An alkaline solution helped the fledgling vesicles keep their electric charge. A saltwater environment also proved helpful, as the fat molecules banded together more tightly in a salty fluid, forming more stable vesicles.

For the first time, the researchers succeeded at creating self-assembling protocells in an environment similar to that of hydrothermal vents. They found that the heat, alkalinity and salt did not impede the protocell formation, but actively favoured it.

“In our experiments, we have created one of the essential components of life under conditions that are more reflective of ancient environments than many other laboratory studies,” Dr Jordan said.

“We still don’t know where life first formed, but our study shows that you cannot rule out the possibility of deep-sea hydrothermal vents.”

The researchers also point out that deep-sea hydrothermal vents are not unique to Earth.

Professor Lane said: “Space missions have found evidence that icy moons of Jupiter and Saturn might also have similarly alkaline hydrothermal vents in their seas. While we have never seen any evidence of life on those moons, if we want to find life on other planets or moons, studies like ours can help us decide where to look.”

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The study involved researchers from UCL and Birkbeck, University of London, and was funded by the BBSRC and bgC3.