[ad_1]
New research has provided clues that galactic magnetars – young pulsars that spin slower than regular pulsars and have the strongest magnetic fields in the universe – located near a black hole, could possibly be the source of “rapid millisecond burst radio” or FRB – high energy explosions that originate beyond our galaxy but whose exact nature and origin is unknown.
“Over 60 of these surprise shows have been recorded so far,” Dennis Overbye reports for The New York Times. “The only thing astronomers agree on is that these signals are probably not from aliens saying hello.”
Origin – “A special place”
“Perhaps the FRBs come from a dense cluster of matter or gas, like the remains of an exploding star,” says astronomer Cherry Ng of the University of Toronto, of a study carried out in 2019 by the Canadian Hydrogen Intensity Mapping Experiment, or Chime, in BC .. “” Or maybe they appeared near black holes in the heart of distant galaxies, “said Ng, who added that the burst had to come from “a special place.”
“It could mean in some kind of dense clump like a supernova remnant or near the central black hole in a galaxy,” Ng said.
“Maybe we should thank our lucky stars,” Overbye observes, “that we don’t live in such a” special place “in our own galaxy. “
The two questions
“There are two main questions regarding the origin of FRBs,” said astrophysicist Bing Zhang of the University of Nevada, Las Vegas, whose team has made new observations on the sources of rapid radio bursts, or FRB, which led to a series of groundbreaking discoveries. which could finally shed light on the physical mechanism of FRBs – using the Five Hundred Meter Aperture Spherical Telescope (FAST) in Guizhou, China.
Unknown phenomena – “Repeat FRBs formed by events never seen before”
“The first is what are the drivers of FRBs and the second is what is the production mechanism of FRBs. We have found the answer to the second question, ”said Zhang of the most enigmatic and powerful events in the cosmos. So far, scientists don’t know what causes them, it involves incredible energy – equivalent to the amount released by the Sun in 80 years.
Two competing theories have been proposed to interpret the mechanism of FRBs, reports UNLV: “One theory is that they are similar to gamma-ray bursts (GRBs), the most powerful explosions in the universe. The other theory compares them more to radio pulsars, which are spinning neutron stars that emit bright, coherent radio pulses. GRB-type models predict a non-variable polarization angle in each burst, while pulsar-type models predict variations in the polarization angle. “
“Signals from a strange star system” – “Heartbeat” of ultra-bright flashes
GRB or Pulsar?
The team used Chinese FAST to observe a repeating FRB source and discovered 11 bursts. Surprisingly, seven of the 11 light bursts showed various polarization angle variations during each burst. The polarization angles did not only vary in each burst, the variation patterns were also diverse among the bursts.
“Our observations essentially exclude GRB-type models and provide support for pulsar-type models,” said K.-J. Lee of the Kavli Institute of Astronomy and Astrophysics, Peking University, and corresponding author of the article.
Four more articles on FRBs were published in Nature on November 4. These include multiple research papers published by the FAST team led by Zhang and collaborators from the National Astronomical Observatories of China and Peking University. Researchers affiliated with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and the Survey for Transient Astronomical Radio Emission 2 (STARE2) group have also joined in these publications.
“Something Unexpected Is Happening” – Astronomers Tune In To Fast Radio Bursts Cosmic Frequency
“Just as the first article advanced our understanding of the mechanism behind FRBs, these articles solved the challenge of their mysterious origin,” Zhang explained.
City-Size Neutron Stars – “Possess the Strongest Magnetic Fields in the Universe”
Magnetars are incredibly dense city-sized neutron stars that have the strongest magnetic fields in the universe. Magnetars sometimes produce short x-ray or mild gamma-ray bursts by dissipating magnetic fields, so they have long been speculated as plausible sources to power FRBs during high-energy bursts.
“New Clues” – The causes of the enigmatic rapid radio bursts (FRB) remain unknown
The first conclusive evidence for this came on April 28, 2020, when an extremely bright radio burst was detected from a magnetar sitting right in our backyard – at a distance of about 30,000 light years from Earth. in the Milky Way. As expected, the FRB was associated with a bright X-ray burst.
The most magnetized objects in the universe
“We now know that the so-called magnetars can produce at least some or maybe all of the FRBs in the universe,” Zhang said.
The event was detected by CHIME and STARE2, two telescope arrays with many small radio telescopes that are suitable for detecting light events from a large area of the sky.
Intriguing discoveries “without detection”
Zhang’s team has been using FAST to observe the magnetar source for some time. Unfortunately, when the FRB happened, FAST was not looking for the source. Nonetheless, FAST made some intriguing “detection-free” findings and reported them in one of the November 4 Nature articles. During the FAST observation campaign, 29 other bursts of X-rays were emitted by the magnetar. However, none of these bursts was accompanied by a radio burst.
“Our non-detections and the detections by the CHIME and STARE2 teams give a complete picture of the FRB-magnetar associations,” said Zhang.
“Thanks to recent breakthroughs in observation, the theories of the FRB can finally be critically reviewed,” said Zhang. “The production mechanisms of FRBs are considerably reduced. However, many questions remain open. It will be an exciting area in the years to come.
Nature.com Sources: No pulsed radio emission during a burst phase of a galactic magnetar ”. “The physical mechanisms of rapid radio bursts”. “Different polarization angles oscillate from a source of repetitive fast radio bursts”
The Daily Galaxy, Max Goldberg, via Nature, UNLV and The New York Times
Image credit, top of page: is a NASA image of the Crab Nebula, powered by a rapidly spinning, highly magnetized neutron star called a pulsar, which formed when a massive star ran out of sound nuclear fuel and collapsed. The combination of rapid rotation and a strong magnetic field in the crab generates an intense electromagnetic field which creates jets of matter and anti-matter moving away from the north and south poles of the pulsar, and an intense wind s ‘flowing in the equatorial direction.
The last image of the crab is an x-ray composite of Chandra (blue and white), NASA’s Hubble Space Telescope (purple), and NASA’s Spitzer Space Telescope (pink). The extent of the x-rays in this image is smaller than others because the extremely energetic electrons emitting x-rays radiate their energy faster than the low-energy electrons emitting optical and infrared light.
[ad_2]
Source link