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Leiden, Jul 2: Astronomers have discovered a luminous galaxy caught in the act of reionizing its surrounding gas only 800 million years after the Big Bang.

The research, led by Romain Meyer, PhD student at UCL in London, UK, has been presented at the virtual annual meeting of the European Astronomical Society (EAS).

Studying the first galaxies that formed 13 billion years ago is essential to understanding our cosmic origins. One of the current hot topics in extragalactic astronomy is 'cosmic reionization,' the process in which the intergalactic gas was ionized (atoms stripped of their electrons).

Cosmic reionization is similar to an unsolved murder: We have clear evidence for it, but who did it, how and when? We now have strong evidence that hydrogen reionization was completed about 13 billion years ago, in the first billion years of the universe, with bubbles of ionized gas slowly growing and overlapping.

The objects capable of creating such ionized hydrogen bubbles have however remained mysterious until now: the discovery of a luminous galaxy in which 60-100 percent of ionizing photons escape, is likely responsible for ionizing its local bubble. This suggests the case is closer to being solved.

The two main suspects for cosmic reionization are usually 1) a population of numerous faint galaxies leaking ~10 percent of their energetic photons, and 2) an 'oligarchy' of luminous galaxies with a much larger percentage (>50 percent) of photons escaping each galaxy.

In either case, these first galaxies were very different from those today: galaxies in the local universe are very inefficient leakers, with only <2-3 percent of ionizing photons escaping their host. To understand which galaxies governed cosmic reionization, astronomers must measure the so-called escape fractions of galaxies in the reionization era.

The detection of light from excited hydrogen atoms (the so-called Lyman-alpha line) can be used to infer the fraction of escaping photons. On the one hand, such detections are rare because reionization-era galaxies are surrounded by neutral gas which absorbs that signature hydrogen emission.

On the other hand, if this hydrogen signal is detected it represents a 'smoking gun' for a large ionized bubble, meaning we have caught a galaxy reionizing its surroundings. The size of the bubble and the galaxy's luminosity determines whether it is solely responsible for creating this ionized bubble or if unseen accomplices are necessary.

The discovery of a luminous galaxy 800 million years after the Big Bang supports the scenario where an 'oligarchy' of bright leakers emits most of the ionizing photons.

"It is the first time we can point to an object responsible for creating an ionized bubble, without the need for a contribution from unseen galaxies.

Additional observations with the upcoming James Webb Space Telescope will enable us to study further what is likely one of the best suspects for the unsolved case of cosmic reionization," said Meyer.

Amid the rapid spread of the novel coronavirus (COVID-19), which has infected 73 people in India and killed more than 4,500 individuals globally, doctors have advised that in addition to regularly washing hands, one should also disinfect their smartphone every 90 minutes with alcohol-based hand sanitizer.

Ravi Shekhar Jha, Head of Department at Fortis Escorts Hospital in Faridabad said the best method to disinfect your smartphone is to use regular doctor spirit or the alcohol-based hand sanitizer at least every 90 minutes.

"Avoid touching your eyes, mouth, or nose. The best option is to use a phone cover or a Bluetooth device and try to touch your phone as less as possible. We would also recommend cleaning your phone at least twice a day," Jha told IANS.

According to research, published in 2018 by Insurance2Go, a gadget insurance provider, revealed that smartphone screens have three times more germs than a toilet seat.

One in 20 smartphone users was found to clean their phones less than every six months, said the study.

"In the time of fear of coronavirus, smartphones should also be disinfected with alcohol-based sanitizer rub. Pour few drops of sanitizer on a tiny clean cotton pad and rub it safely on your entire phone," said Jyoti Mutta, Senior Consultant, Microbiology, Sri Balaji Action Medical Institute in New Delhi.

"You can repeat this process every evening coming back home after an entire day out at work and once in the morning before going out," Mutta added.

"Maintain basic cleanliness, and try to avoid using other's phones especially if suffering from respiratory illness or flu-like symptoms as there is no other way to disinfect these regular gadgets," she stressed.

Another study from the University of Surrey in the UK, also found that the home button on your smartphone may be harbouring millions of bacteria - some even harmful.

The World Health Organisation (WHO) declared the novel coronavirus as a global pandemic on Wednesday. The death toll of COVID-19 has crossed the 4,500 marks and confirmed cases globally have touched one lakh as per the reports.

According to Suranjeet Chatterjee, Senior Consultant in Internal Medicine Department of Indraprastha Apollo Hospitals in New Delhi, "We should frequently wash our hands, cover our coughs and it is important to adapt to other good hygiene habits that are most important in such a situation."

"Coronavirus and other germs can live on surfaces like glass, metal or plastics and phones are bacteria-ridden. It is necessary that we sanitize our hands frequently and make sure that our hands are clean all the time," Chatterjee told IANS.

"The emphasis should be laid on sanitising our hands rather than sanitizing the phone - once in a while the phone can be sanitized under the guidance of the makers of the phone," Chatterjee stressed.

According to the global health agency, the most effective way to protect yourself against coronavirus is by frequently cleaning of your hands with alcohol-based hand rub or washing them with soap and water.

The WHO's report showed the virus infects people of all ages, among which older people and those with underlying medical conditions are at a higher risk of getting infected.

People should eat only well-cooked food, avoid spitting in public, and avoid close contact, the WHO said, adding that it is important for people to seek medical care at the earliest if they become sick.

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.