Vikram still missing on Moon, wait till Oct: NASA

New Delhi, Mar 20: The four men convicted of the gang rape and murder of a Delhi woman on December 16, 2012 were hanged in the darkness of pre-dawn on Friday, ending a horrific chapter in India's long history of sexual assault that had seared the nation's soul. Mukesh Singh (32), Pawan Gupta (25), Vinay Sharma (26) and Akshay Kumar Singh (31) were executed at 5.30 am for the savage assault in an empty moving bus on the 23-year-old physiotherapy intern who came to be known the world over as Nirbhaya, the fearless one.

This is the first time that four men have been hanged together in Tihar Jail, South Asia's largest prison complex that houses more than 16,000 inmates. The executions were carried out after the men exhausted every possible legal avenue to escape the gallows. Their desperate attempts only postponed the inevitable by less than two months after the first date of execution was set for January 22.

They were hanged at 5.30 am, Director General of Prison Sandeep Goel said.

After raping and brutalising the woman, the men, one of whom was a juvenile at the time, dumped her on the road and left for dead on the cold winter night. Her friend who was with her was also severely beaten and thrown out along with her. She was so severely violated that her insides were spilling out when she was taken to hospital. She died in a Singapore hospital after battling for her life for a fortnight.

Six people, including the four convicts and the juvenile, were named as accused.

While Ram Singh allegedly committed suicide in the Tihar Jail days after the trial began in the case, the juvenile was released in 2015 after spending three years in a correctional home.

The road to the gallows was a long and circuitous one, going through the lower courts, the High Court, the Supreme Court and the president's office before going back to the Supreme Court that heard and rejected various curative petitions.

The death warrants were deferred by a court thrice on the grounds that the convicts had not exhausted all their legal remedies and that the mercy petition of one or the other was before the president.

On March 5, a trial court issued fresh death warrants for March 20 at 5.30 am as the final date for the execution.

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.