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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.

New Zealand's research institute in Antarctica is scaling back the number of projects planned for the upcoming season, in an effort to keep the continent free of coronavirus, it was reported on Tuesday.

The government agency, Antarctica New Zealand, told the BBC on Tuesday that it was dropping 23 of the 36 research projects.

Only long-term science monitoring, essential operational activity and planned maintenance will go ahead.

The upcoming research season runs from October to March.

"As COVID-19 sweeps the planet, only one continent remains untouched and (we) are focused on keeping it that way," Antarctica New Zealand told the BBC.

The organisation's chief executive Sarah Williamson said the travel limits and a strict managed isolation plan were the key factors for keeping Scott Base - New Zealand's research facility - virus free.

"Antarctica New Zealand is committed to maintaining and enhancing the quality of New Zealand's Antarctic scientific research. However, current circumstances dictate that our ability to support science is extremely limited this season" she said.

Earlier in April, Australia announced that it would scale back its activity in the 2020-21 summer season.

This included decreasing operational capacity and delaying work on some major projects.

Twitter has hinted that it is planning a paid subscription platform that can be reused by other teams in the future.

The news that the micro-blogging platform is building a subscription platform with a team codenamed "Gryphon" resulted in Twitter stock rising over 8% on Wednesday.

Twitter revealed its plan via a job listing that seeks a full-stack senior software engineer in New York to join "Gryphon".

Interestingly, Twitter "edited" the job listing once the news broke, removing the part about "Gryphon" and any mention of their internal team or their subscription feature. The listing said the company is looking for an Android engineer to "work on a bevy of backend engineering teams to build components that allow for experimentation to deliver the best experience possible to all of our users".

Later, Twitter users noticed that the company restored the earlier job listing that mentioned the upcoming subscription platform and "Gryphon".

A spokesperson for Twitter told CNN on Wednesday that it's only a job posting, not a product announcement.

This is not the first time Twitter has thought of a paid product. 

In 2017, it sent out a survey to users and a preview of what a premium offering of its TweetDeck app might look like, including breaking news alerts and more analytics, according to The Verge.

"We're conducting this survey to assess the interest in a new, more enhanced version of Tweetdeck. We regularly conduct user research to gather feedback about people's Twitter experience and to better inform our product investment decisions, and we're exploring several ways to make TweetDeck even more valuable for professionals," a Twitter spokesperson had said at that time.