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Washington D.C., Feb 6: An international team of astronomers has found an unusual monster galaxy that existed about 12 billion years ago when the universe was only 1.8 billion years old.

The team of astronomers was led by scientists at the University of California, Riverside.

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 ultra massive 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," Forrest added.

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.

The 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 professor stated.

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.

"We have caught XMM-2599 in its inactive phase," Wilson said, who led the W. M. Keck Observatory data acquisition
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," he stated.

The study was supported by grants from the National Science Foundation and NASA.

Facebook will introduce a new notification screen on its platform that will warn users if the article they are about to share is over 90 days old, the company announced on Thursday.

“We’re starting to globally roll out a notification screen that will let people know when news articles they are about to share are more than 90 days old,” Facebook wrote in a blog post.

The social media platform had previously introduced a context button in 2018 that provides information about the sources of articles in the News Feed. Building upon that, the new feature will inform users about the timeliness of the article.

“To ensure people have the context they need to make informed decisions about what to share on Facebook, the notification screen will appear when people click the share button on articles older than 90 days, but will allow people to continue sharing if they decide an article is still relevant,” Facebook said.

The social media giant stated that timeliness is important in understanding the context of an article and curbing the spread of misinformation on the platform.

“News publishers, in particular, have expressed concerns about older stories being shared on social media as current news, which can misconstrue the state of current events. Some news publishers have already taken steps to address this on their own websites by prominently labelling older articles to prevent outdated news from being used in misleading ways,” Facebook added.

Apart from this, the platform will also be testing a similar notification screen for information related to the global Covid-19 pandemic. The notification screen will provide information about the source of the link shared in a post if the link is related to information on Covid-19. It will also direct people to its previously introduced Covid-19 information centre for “authoritative” health information, it said.

New Delhi, Jun 29: Witnessing azure skies and breathable air for the last three months, Delhi on Monday recorded deterioration in its air quality, with particulate matter with diameter of 2.5 and 10 microns -- too small to be filtered out of the human body -- standing at 52 and 297 micrograms per cubic respectively.

Gufran Beig, Project Director of System of Air Quality Weather Forecasting and Research (SAFAR), said that the sudden spike in air pollution is due to a mild dust storm blowing from Rajasthan.

"Since the wind direction is changing and moist air is coming in, the air quality in Delhi will become better by tomorrow," Beig told IANS.

Central Pollution Control Board (CPCB) data showed that the overall air quality near Delhi Technical University (DTU) area stood at 326 micrograms per cubic, followed by 308 at Narela and 307 at Mundka.

Out of 36 stations, the AQI in as many as 30 stations was above 200 micrograms per cubic till 1 pm on Monday.

The System of Air Quality Weather Forecasting and Research categorises air quality in the 0-50 range as good, 51-100 as satisfactory, 101-200 as moderate, 201-300 as poor, 301-400 as very poor, and above 400 as severe.

According to SAFAR's website, "PM 10 (coarser dust particle) is the lead pollutant. AQI is likely to improve to moderate category by tomorrow, and further improvement is expected by July 1."

Researchers indicated that PM 10 and PM 2.5 will be 170 and 47 micrograms per cubic on Tuesday.

With no vehicles plying on the roads or industries shut due to the lockdown since March 25, Delhi's air quality had improved drastically.

According to a study conducted by the Indian Institute of Technology (IIT), Delhi, if the low levels of air pollution reached during the lockdown period are maintained, India's annual death toll could reduce by 6.5 lakh.