Tag: FRBs

Scientists: The activity at the few known fast radio bursts suggests they resemble earthquakes

8:57 am

By analyzing 7,000 fast radio bursts (FRBs) detected from the three known FRBs, two scientists have found that the behavior appears to resemble the main quake and aftershocks seen in earthquakes.

The duo found that the arrival times of bursts from FRB20121102A showed a high degree of correlation, with many more bursts arriving within a second of each other than would be expected if the generation of bursts were completely random. This correlation faded away at longer timescales, with bursts separated by over a second arriving completely at random.

They drew similarities with this behaviour to how earthquakes produce secondary aftershocks in the hours or days following a tremor, but then become completely unpredictable once an episode of aftershocks passes. Moreover, they found that the rate of these FRB “aftershocks” follows the same Omori-Utsu law that characterises the occurrence of earthquake aftershocks on Earth. The law states that shortly after a large earthquake, the rate of aftershocks remains constant over a brief period of minutes to hours, after which the aftershock rate drops, decaying as roughly the inverse of the time since the main shock.

As always there is uncertainty about this conclusion. The magnitudes of the main quake and the pre- and after-shocks do not follow the curve pattern of earthquakes. Instead pre- and after-shocks can be as powerful.

The present theory is that FRBs are quakes in the crust of neutron stars, though this remains unconfirmed.

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Astronomers detect what they think is the most distant known fast radio burst yet

9:50 am

The uncertainty of science: Using ground-based radio and optical telescopes, astronomers think they have detected the most distant known fast radio burst yet, coming from a galaxy thought to be eight billion light years away.

On 10 June 2022, CSIRO’s ASKAP radio telescope on Wajarri Yamaji Country was used to detect a fast radio burst, created in a cosmic event that released, in milliseconds, the equivalent of our Sun’s total emission over 30 years.

“Using ASKAP’s array of dishes, we were able to determine precisely where [in the sky] the burst came from,” says Dr Ryder, the first author on the paper. “Then we used the European Southern Observatory (ESO) Very Large Telescope (VLT) in Chile to search for the source galaxy, finding it to be older and further away than any other FRB source found to date, and likely within a small group of merging galaxies.”

Note that the scientists have not actually measured the distance of this burst. They assume it sits at the same distance of the group of merging galaxies that surround it. Only about fifty fast radio bursts have so far been detected. As yet there is no accepted explanation as to what causes them, though knowing their assumed distance helps narrow the possibilities significantly.

The scientists also think they can use the energy from this burst to measure the intervening matter between it and Earth, and thus get a better estimate of the mass of the universe.

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Astronomers discover 25 more repeating fast radio bursts, doubling the number known

10:18 am

Using a ground-based radio telescope in Canada that scans the northern sky each night, astronomers have discovered another 25 repeating fast radio bursts (FRBs), doubling the number that was previously known.

One surprising aspect of this new research is the discovery that many repeating FRBs are surprisingly inactive, producing under one burst per week during CHIME’s observing time. Pleunis believes that this could be because these FRBS haven’t yet been observed long enough for a second burst to be spotted.

The cause of FRBs still remains unsolved. The knowledge of specific repeating FRBs however will go a long way to figuring out this mystery, because other telescopes will be able to better observe later bursts, knowing when they are expected to occur.

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Chinese scientists detect a fast radio burst that defies the theories

10:08 am

The uncertainty of science: Using their large FAST radio telescope, Chinese scientists revealed this week that they have detected a new fast radio burst (FRB) whose behavior and location does not fit the present tentative theories for explaining these mysterious deep space objects.

The FRB was an exception from the beginning as it flared again and again in observations recorded by the Five-hundred-meter Aperture Spherical radio Telescope (FAST), which nestles among the hills of China’s Guizhou province. The multiple flares put the source among the few percent of FRBs that repeat. But unlike most repeaters, this one doesn’t have any apparent cycle of bursting and quiescence.

“FRB 20190520B is the only persistently repeating fast radio burst known so far, meaning that it has not been seen to turn off,” Li says.

In addition, whatever made the FRB is also emitting a constant buzz of radio waves. Astronomers have found an association with a persistent radio source in only two other FRBs, and for one of these the low-level radio waves seem to come from ongoing star formation in the host galaxy. For FRB 20190520B, though, the radio source is far more compact, and Li’s team thinks the radio waves probably come from the FRB source itself.

The data also suggests the location does not fit the theories, and even suggests that FRBs might not all come from magnetars, as presently proposed.

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First fast radio burst detected in Milky Way

10:57 am

Astronomers using both space- and ground-based telescopes have detected for the first time a fast radio burst occurring inside the Milky Way, finding that it came from a magnetar, a pulsar with an extremely powerful magnetic field.

The radio component was discovered by the Canadian Hydrogen Intensity Mapping Experiment (CHIME), a radio telescope located at Dominion Radio Astrophysical Observatory in British Columbia and led by McGill University in Montreal, the University of British Columbia, and the University of Toronto.

A NASA-funded project called Survey for Transient Astronomical Radio Emission 2 (STARE2) also detected the radio burst seen by CHIME. Consisting of a trio of detectors in California and Utah and operated by Caltech and NASA’s Jet Propulsion Laboratory in Southern California, STARE 2 is led by Bochenek, Shri Kulkarni at Caltech, and Konstantin Belov at JPL. They determined the burst’s energy was comparable to FRBs.

By the time these bursts occurred, astronomers had already been monitoring their source for more than half a day.

Late on April 27, NASA’s Neil Gehrels Swift Observatory spotted a new round of activity from a magnetar called SGR 1935+2154 (SGR 1935 for short) located in the constellation Vulpecula. It was the object’s most prolific flare-up yet – a storm of rapid-fire X-ray bursts, each lasting less than a second. The storm, which raged for hours, was picked up at various times by Swift, NASA’s Fermi Gamma-ray Space Telescope, and NASA’s Neutron star Interior Composition Explorer (NICER), an X-ray telescope mounted on the International Space Station.

Later observations detected X-rays from the same source. While this does not prove that all fast radio bursts come from magnetars, it does prove that at least some do.

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A fast radio burst that beats every sixteen days

11:59 am

Astronomers have now added to the mystery of fast radio bursts (FRBs), of which about a hundred are known, by discovering one in a nearby galaxy that has a regular outburst every 16.35 days.

Earlier this year CHIME worked with astronomers in Europe to pinpoint the origin of a particular FRB emission — called FRB 180916.J0158+65 — to a galaxy located 500 million light years from Earth.

Now CHIME has determined that FRB 180916 pulses at predictable intervals more than two weeks apart. “It tells us that the origin of at least some FRBs is astrophysically regular in nature, but on long enough time scales that they may be tied to something different than a rotating, compact object — perhaps something like an orbiting system,” said Newburgh, whose lab builds instrumentation for collecting data about the history of the cosmos

Or to put it another way, they really haven’t any idea yet what exactly causes these bursts. The new data however will help formulate better theories, that I guarantee will be contradicted by subsequent new data. At the moment there is so little known about FRBs that any theory must be looked at with great skepticism.

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New radio telescope discovers many new Fast Radio Bursts

4:01 pm

A new radio telescope in Canada, designed to detect the mysterious and as-yet unexplained Fast Radio Bursts (FRB), has in the past year raised the total of known FRBs from 30 to 700, including nine repeating bursts.

This confirms an earlier very preliminary analysis that there were two different types of bursts, those that repeat and those that don’t.

Warning: It is very dangerous to take these results too seriously. A lot of uncertainty exists, including some basic facts about the bursts.

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Astronomers identify for the first time the source of a fast radio burst

7:25 pm

For the first time astronomers have pinned down the location of a fast radio burst (FRBs), short bursts lasting only seconds that were only discovered about a decade ago.

A dim dwarf galaxy 2.5 billion light years from Earth is sending out the mysterious millisecond-long blasts of radio waves, researchers report Wednesday in Nature and Astrophysical Journal Letters. The bursts traverse vast expanses of time and intergalactic space before reaching our planet. “This really is the first ironclad association of a fast radio burst with another astronomical source, so it’s a pretty huge result,” said Duncan Lorimer, an astronomer at West Virginia University who reported the first detection of a fast radio burst (FRB) in 2007.

The uncertainty of science: Only 18 FRBs have been identified since they were first discovered. Until now, it was unclear whether they occurred in our galaxy or beyond, though it was suspected they were coming from other galaxies. This discovery proves that. What remains unknown is what causes the burst, which signals an energy pulse equivalent to that of 500 million suns.

“I am not exaggerating when I say there are more models for what FRBs could be than there are FRBs,” said Cornell astronomer Shami Chatterjee, the lead author of the new Nature paper. Many scientists think the bursts are emitted by distant neutron stars, the super-dense embers of exploded suns. But some believe they must originate in our own galaxy. Still more suggest that FRBs could be caused by cataclysms like a supernova or a collision of two stars. This last theory was compelling because most FRB detections were one-off events — astronomers never spotted more than one flare from a single source.

Today’s announcement was made possible by the fact that the burst itself is repeating. In fact, it is the only FRB so far known to do so, which also means that what they learn about it might not be applicable to the other bursts.

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