- 3196 - FRBs - Fast Radio Bursts and CHIME? CHIME is a satellite that detected over 500 Fast Radio Burst in its first year of operation. Already it is providing new clues to what’s causing FRB‘s.. What are Fast Radio Bursts and how is CHIME measuring them?
- ------------- 3196 - FRBs - Fast Radio Bursts and CHIME?
- Much like Dark Matter and Dark Energy, Fast Radio Burst (FRBs) are one of those crazy cosmic phenomena that continue to mystify astronomers. These incredibly bright flashes register only in the radio band of the electromagnetic spectrum, occur suddenly, and last only a few milliseconds before vanishing without a trace.
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- As a result, observing them with a radio telescope is challenging and requires extremely precise timing. This is why the “Dominion Radio Astrophysical Observatory” (DRAO) began its “Hydrogen Intensity Mapping Experiment” (CHIME) in 2017.
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- CHIME detected more than 500 FRBs in its first year of operation and more than 1,000 since it commenced operations!
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- Astronomers have only been studying FRBs since 2007 when the first event was reported. Prior to 2017 when CHIME became operational, only about two dozen had ever been observed and their origin remains unknown.
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- However, we now know that as cosmological phenomena go, they are ubiquitous, with thousands of events arriving at Earth every day from every corner of the sky.
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- Originally conceived to map the distribution of hydrogen over much of the observable universe, the novel design of CHIME also makes it highly effective for the study of FRBs. In addition to being stationary with no moving parts, it is optimized for high “mapping speed,” thanks to its large instantaneous field of view , about 200 square degrees and broad frequency coverage, 400 to 800 megahertz (MHz).
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- While most radio astronomy is performed using large dish antennas that focus light from different parts of the sky, CHIME is motionless and focuses incoming signals onto its four massive cylindrical radio antennas.
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- The telescope also relies on a powerful digital signaling processor, called a “correlator“, that is capable of sorting through data at a rate of about 7 terabits per second.
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- In its first year of operation between 2018 and 2019, it detected 535 new FRBs. After mapping the timing and locations, scientists found that the bursts were evenly distributed in space and occur at a rate of about 800 per day, which is the most precise estimate of the overall rate of FRBs to date. 800 per day!
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- If your eyes could see radio flashes the way you can see camera flashes, you would see them all the time whenever you just looked up.”
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- There are FRBs that repeat and those that are a one-off occurrence. “One-off bursts” are believed to be entirely natural in occurrence, “repeating FRBs” defy conventional explanation. To date, only 18 FRBs have been reported that burst repeatedly, whereas the rest appear to be singular.
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- The repeating FRBs also differ in that they last slightly longer than non-repeating ones, and emit more focused radiofrequency bursts. What this suggests is that those FRBs that repeat and those that don’t have different mechanisms and astrophysical sources. This is an important step in resolving what causes these enigmatic bursts and something astronomers hope to understand soon.
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- Another benefit to all these recorded events is the way they will allow astronomers and cosmologists to gain a better understanding of the structure and distribution of matter in the Universe. The reason is that as radio waves travel across space, they pass through the dust and gas that permeate interstellar and intergalactic space. This can distort or disperse the properties and trajectory of radio waves.
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- The degree to which a radio wave is dispersed can give clues to how much gas it passed through, and possibly how much distance it has traveled from its source. From each of the 535 FRBs that CHIME detected, the measured dispersion found that most bursts likely originated in distant galaxies. The fact that they were bright enough to be detected by CHIME suggests that they must have been produced by very energetic sources.
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- As CHIME and other radio observatories detect more FRBs, scientists hope to pin down exactly what kind of exotic and powerful phenomenon causes them.
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- Each FRB gives us some information of how far they’ve propagated and how much gas they’ve propagated through. With large numbers of FRBs, we can hopefully figure out how gas and matter are distributed on very large scales in the universe.
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- Alongside the mystery of what FRBs are themselves, there’s also the exciting potential for FRBs to be used as powerful cosmological probes into our understanding of the structure of the universe. ------------------------- Other reviews available:
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- 2907 - FAST RADIO BURSTS - what is the source? FRBs are powerful, millisecond-duration radio waves coming from deep space outside the Milky Way Galaxy. They have been among the most mysterious astronomical phenomena ever observed. These waves are only milliseconds in duration.
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- June 20, 2021 FRBs - Fast Radio Bursts and CHIME? 3196
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