Washington, July 13 : For the first time, scientists have found the source of a high-energy ghostly particle, known as neutrino, that travelled 3.7 billion years at almost the speed of light to reach Earth.
Using NASA's Fermi Gamma-ray space telescope, scientists traced the path of this hard-to-catch particle to a blast of gamma-ray light from a distant supermassive black hole in the constellation Orion.
Scientists believe that high-energy neutrinos are created by the most powerful events in the cosmos, such as galaxy mergers and material falling onto supermassive black holes.
They travel at speeds just shy of the speed of light and rarely interact with other matter, allowing them to travel unimpeded across distances of billions of light-years.
The findings detailed in the journal Science marked the detection of the source of such a particle for the first time.
"Again, Fermi has helped make another giant leap in a growing field we call multimessenger astronomy," said Paul Hertz, Director of the Astrophysics Division at NASA Headquarters in Washington.
"Neutrinos and gravitational waves deliver new kinds of information about the most extreme environments in the universe. But to best understand what they're telling us, we need to connect them to the 'messenger' astronomers know best - light," Hertz added.
The neutrino was discovered last year in Antarctica by an international team of scientists using the US National Science Foundation's IceCube Neutrino Observatory.
It hit the Antarctic ice with the energy of about 300 trillion electron volts -- more than 45 times the energy achievable in the most powerful particle accelerator on Earth.
This high energy strongly suggested that the neutrino had to be from beyond our solar system.
Backtracking the path through IceCube indicated where in the sky the neutrino came from, and automated alerts notified astronomers around the globe to search this region for flares or outbursts that could be associated with the event.
Data from Fermi revealed enhanced gamma-ray emission from a well-known active galaxy at the time the neutrino arrived.
This is a type of active galaxy called a blazar, with a supermassive black hole with millions to billions of times the Sun's mass that blasts jets of particles outward in opposite directions at nearly the speed of light.
Blazars are especially bright and active because one of these jets happens to point almost directly toward Earth.
Fermi scientist Yasuyuki Tanaka at Hiroshima University in Japan was the first to associate the neutrino event with the blazar designated TXS 0506+056 (TXS 0506 for short), NASA said.
"The most extreme cosmic explosions produce gravitational waves, and the most extreme cosmic accelerators produce high-energy neutrinos and cosmic rays," said Regina Caputo of NASA's Goddard Space Flight Center in Greenbelt, Maryland.
"Through Fermi, gamma rays are providing a bridge to each of these new cosmic signals," Caputo said.
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New Delhi (PTI): Senior Congress leader Shashi Tharoor, who on Friday attended a banquet for Russian President Vladimir Putin at the Rashtrapati Bhawan, on Saturday described the atmosphere there as "warm" and "engaging", and said he enjoyed his conversations with many of the attendees.
Tharoo’s remarks came a day after President Droupadi Murmu hosted a banquet for the visiting Russian president at the Rashtrapati Bhavan here.
“Attended the @rashtrapatibhvn banquet for President Putin last night. A warm and engaging atmosphere reigned. Enjoyed my conversations with many of the attendees, especially my dining companions from the Russian delegation!" Tharoor said in a social media post.
Murmu, while welcoming President Putin and his delegation at the banquet, had said that his visit marked an important milestone -- the 25th anniversary of the India-Russia strategic partnership, which was established in October 2000 during his first visit to the country as president.
Murmu also appreciated Putin's support and personal commitment to the India-Russia special and privileged strategic partnership.
The Congress on Friday said that the leaders of the opposition, Mallikarjun Kharge and Rahul Gandhi, were not invited to the banquet, and took a swipe at Tharoor for accepting the invite.
The party’s media and publicity department head, Pawan Khera, accused the government of breaking protocols daily and not believing in democratic principles.
“There is no invite to both the LoPs, Mr (Mallikarjun) Kharge and Mr (Rahul) Gandhi. This comes as a surprise, but I don't think we should be surprised. This government is known to be breaching all protocols. What else to say, ask the government,” Khera said on Friday.
Asked about Tharoor accepting the invite for the banquet, Khera said, "Ask Mr Tharoor. All of us who are in the party, if our leaders don't get invited and we get invited, we need to question our own conscience and listen to our conscience. Politics has been played in inviting or not inviting people, which in itself is questionable, and those who accept such an invite are also questionable."
“We would have listened to our voice of conscience,” he added.
Earlier, Tharoor had said that there was a time when the chairman of the external affairs committee was routinely invited, but that practice seems to have stopped some years ago.
On Thursday, Congress leader Rahul Gandhi alleged that the government tells visiting foreign dignitaries not to meet the leader of opposition due to its "insecurity".
His remarks came hours ahead of Putin's two-day visit to India.
