From the depths of the cosmos, an invisible fireworks show unfolds in the form of Fast Radio Bursts (FRBs). These are the fleeting blasts of energy that are brighter than entire galaxies. But where do they come from and why are they important? Let’s try to resolve this mysterious quest in today’s blog….
Introduction:
Fast Radio Bursts have frequencies of around 1400 hertz and can occur at random points in the sky over Earth each day. However, by the time this Energy gets to Earth, it is much weaker. These short-lived radio-wave blasts can gather information about cosmic environments, like the clouds of interstellar gas they pass through. That makes studying FRBs a pressing concern for astronomers who want to map the universe.
At Space India, through Space Explorers Workshop, “Fingerprints of the Universe” astronomers understand what the universe is made of by studying the light coming from the celestial bodies. They achieve this using a measurement technique called ‘spectroscopy’. In this session, students are taught to experiment rather than just believe in facts. They experiment and learn that light is a combination of seven colours. They further explore that each spectrum tells a story. It is unique to the object and can give a wide range of information about that object. They then relate this to how astronomers discover mind-boggling facts about objects of the universe using spectroscopy.
What is an FRB signal?
A fast radio burst is a bright and brief burst of electromagnetic radiation (light) seen in radio-wave frequencies. They usually last thousandths of a second. Some FRBs repeat, but the vast majority happen once and disappear forever.
How powerful these signals are?
When radio telescopes spot FRBs from Earth, the strength of the signal is similar to a mobile phone signal from the moon.
Discovery of first FRB:
In 2007 when Duncan Lorimer and David Narkevic, his student were looking through the archival pulsar data recorded by Parkes observatory on 24 July 2001, first fast FRB was discovered. It is referred to as Lorimer burst, since then many FRB’s have been discovered and scientist are studying them keenly.
Recent research in unveiling the mystery of the origin of FRBs:
Astronomers at MIT have identified the source of at least one fast radio burst using a new technique. These findings provided the first conclusive evidence that a fast radio burst can originate from the magnetosphere, the highly magnetic environment immediately surrounding an extremely compact object like a neutron star.
But how?
To determine the origin of FRBs, researchers considered scintillation, the effect that occurs when light from a small bright source filters through a medium, such as a galaxy’s gas. The team believed that estimating the degree to which an FRB scintillates or filters could determine the relative size of the region from where the FRB originated.
To test their idea, the researchers looked to FRB 20221022A, a fast radio burst that was detected by CHIME in 2022, about 200 million light-years away. The signal lasted about two milliseconds, and is a relatively run-of-the-mill FRB, in terms of its brightness. However, the team’s collaborators at McGill University found that FRB 20221022A exhibited one standout property: The light from the burst was highly polarized, with the angle of polarization tracing a smooth S-shaped curve. This pattern is interpreted as evidence that the FRB emission site is rotating — a characteristic previously observed in pulsars, which are highly magnetized, rotating neutron stars.
Thus, the team at CHIME has discovered that fast radio bursts can originate from very close to a neutron star in highly chaotic magnetic environments.
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