Origin of 'ghost particle' traced to distant black hole
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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Mumbai-Pune Expressway connecting link now fully operational
Mumbai (PTI): The Mumbai-bound carriageway of the Mumbai-Pune Expressway connecting link was opened to vehicular traffic on Saturday noon after a delay caused by the dismantling of inauguration infrastructure and cleaning work, a day after the Pune section became operational.
The 13.3 km-long "missing link", which bypasses a section of the Bhor Ghat stretch of the expressway and cuts travel time between Mumbai and Pune by 25 to 30 minutes, was inaugurated a day earlier by Chief Minister Devendra Fadnavis in the presence of Deputy CMs Eknath Shinde and Sunetra Pawar.
The Pune-bound carriageway of the corridor was opened to traffic immediately; however, the Mumbai-bound section remained closed to traffic for several hours after the inauguration.
An official of the Maharashtra State Road Development Corporation told PTI on Saturday that the opening of the Mumbai-bound carriageway was delayed mainly due to the dismantling of the inauguration infrastructure and cleaning work.
The removal of the stage and other decorations was completed in the morning. The work to load and transport the material slightly delayed the opening of the carriageway.
Vehicular movement on the carriageway began after all the remaining material was cleared and road cleaning was completed, the official added.
The expressway control room said that despite significant vehicular movement, the access-controlled highway has not witnessed any major traffic snarls since Friday evening, after the Pune-bound carriageway of the missing link was opened to traffic.
The Missing Link project connects Khopoli (in Raigad) on the Mumbai side to Kusgaon near Lonavala in Pune district and is expected to make the expressway fully access-controlled, easing congestion in the ghat section.
Developed by the MSRDC and dubbed an "engineering marvel", the project includes two tunnels, two viaducts and a cable-stayed bridge over Tiger Valley. It bypasses the steep, accident-prone ghat section, where frequent traffic snarls are reported during weekends and on public holidays.
