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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.

Cape Canaveral, May 31: SpaceX, the private rocket company of billionaire entrepreneur Elon Musk, launched two Americans into orbit from Florida on Saturday in a landmark mission marking the first spaceflight of NASA astronauts from U.S. soil in nine years.

A SpaceX Falcon 9 rocket lifted off from the Kennedy Space Center at 3:22 p.m. EDT (19:22 GMT), launching Doug Hurley and Bob Behnken on a 19-hour ride aboard the company’s newly designed Crew Dragon capsule bound for the International Space Station.

Just before liftoff, Hurley said, “SpaceX, we’re go for launch. Let’s light this candle,” paraphrasing the famous comment uttered on the launch pad in 1961 by Alan Shepard, the first American flown into space.

Minutes after launch, the first-stage booster rocket of the Falcon 9 separated from the upper second-stage rocket and flew itself back to Earth to descend safely onto a landing platform floating in the Atlantic.

High above the Earth, the Crew Dragon jettisoned moments later from the second-stage rocket, sending the capsule on its way to the space station.

The exhilarating spectacle of the rocket soaring flawlessly into the heavens came as a welcome triumph for a nation gripped by racially-charged civil unrest as well as ongoing fear and economic upheaval from the coronavirus pandemic.

The Falcon 9 took off from the same launch pad used by NASA’s final space shuttle flight, piloted by Hurley, in 2011. Since then, NASA astronauts have had to hitch rides into orbit aboard Russia’s Soyuz spacecraft.

“It’s incredible, the power, the technology,” said U.S. President Donald Trump, who was at Kennedy Space Center at Cape Canaveral in Florida for the launch. “That was a beautiful sight to see.”

The mission’s first launch attempt on Wednesday was called off with less than 17 minutes remaining on the countdown clock. Weather again threatened Saturday’s launch, but cleared in time to proceed with the mission.

SPACEFLIGHT MILESTONES

NASA chief Jim Bridenstine has said resuming launches of American astronauts on American-made rockets from U.S. soil is the space agency’s top priority.

“I’m breathing a sigh of relief, but I will also tell you I’m not gonna celebrate until Bob and Doug are home safely.” Bridenstine said.

For Musk, the launch represents another milestone for the reusable rockets his company pioneered to make spaceflight less costly and more frequent. And it marks the first time commercially developed space vehicles - owned and operated by a private entity rather than NASA - have carried Americans into orbit.

The last time NASA launched astronauts into space aboard a brand new vehicle was 40 years ago at the start of the space shuttle program.

Musk, the South African-born high-tech entrepreneur who made his fortune in Silicon Valley, is also chief executive of electric carmaker and battery manufacturer Tesla Inc. He founded Hawthorne, California-based SpaceX, formally known as Space Exploration Technologies, in 2002.

Hurley, 53, and Behnken, 49, NASA employees under contract to fly with SpaceX, are expected to remain at the space station for several weeks, assisting a short-handed crew aboard the orbital laboratory.

Boeing Co, producing its own launch system in competition with SpaceX, is expected to fly its CST-100 Starliner vehicle with astronauts aboard for the first time next year. NASA has awarded nearly $8 billion combined to SpaceX and Boeing for development of their rival rockets.

Trump also hailed the launch as a major advance toward the goal of eventually sending humans to Mars.

He was joined at the viewing by Musk, as well as Vice President Mike Pence, Commerce Secretary Wilbur Ross, Education Secretary Betsy DeVos, Florida congressman Matt Gaetz and Senator Rick Scott.

Earlier on Saturday, the crew bid goodbye to their families. Prior to climbing into a specially designed Tesla automobile for the ride to the launch site, Behnken told his young son, “Be good for mom. Make her life easy.”

During the drive, Behnken and Hurley passed former astronaut Garrett Reisman who held a sign saying, “Take me with you.”

Mumbai, Jun 12: Following an overwhelming response for the mega rights issue of Mukesh Ambani-owned Reliance Industries, the partly paid-up rights shares are set to debut on stock exchanges on June 15.

The biggest ever Rs 53,124 crore rights issue was subscribed 1.59 times and received bids worth Rs 84,000 crore on June 3.

Reliance said the rights issue saw a huge investor interest, including from lakhs of small investors and thousands of institutional investors, both Indian and foreign.

In 2019, Ambani said in the Reliance's annual general meeting that the company will be net zero debt by March 2021. The company is on course to achieve its target ahead of the deadline.

"In spite of the COVID-19 crisis and the lockdowns, the due-diligence by Saudi Aramco for the planned investment in the O2C business is on track as both the parties are committed and actively engaged," he said recently.

"With a strong visibility to these equity infusions, Reliance is set to achieve net zero debt status ahead of its own aggressive timeline. We believe rights issue was a part of the company's strategy of deleveraging its balance sheet," said Ambani.