Strange radio signal baffles astronomers


When astronomers point our radio telescopes into space, we sometimes detect sporadic bursts of radio waves emanating from the vast expanse of the universe. We call them “radio transients”: Some explode only once, never to be seen again Others turn on and off in predictable patterns.

We believe that most radio is static They come from rotating neutron stars called pulsars, emitting regular flashes of radio waves like cosmic beacons. Generally, These neutron stars spin at incredible speeds, taking seconds or even fractions of a second to complete each rotation.

Recently, We discovered a radio transient unlike anything astronomers had seen before. Not only does it have a cycle nearly an hour long (the longest ever seen), but through many observations we have seen it sometimes emit long, bright flashes, sometimes fast, weak pulses, and sometimes none at all.

What is happening here cannot be fully explained. Most likely it is a very unusual neutron star, but we cannot rule out other possibilities. our Investigation Published in Natural Astronomy.

Meet ASKAP J1935+2148 (the numbers in the name indicate its location on the sky). This term was invented using radio transients ASKAP radio telescope From the CSIRO in Wajari Yamaji Country, Western Australia.

A telescope has a very wide field of view, This means that large blocks of the universe can be probed very quickly. This makes it ideal for discovering new and exciting events.

Using ASKAP, we simultaneously monitor the gamma-ray source and look for pulses from the fast radio burst, ASKAP J1935+2148 is faintly luminous in the data. The signal bounced because it was made up of “circularly polarized” radio waves, meaning the direction of the waves rotates as the signal travels through space.

The signal was detected using CSIRO’s ASKAP radio telescope in Western Australia.

Our eyes They cannot distinguish between circularly polarized light and ordinary unpolarized light. However, ASKAP acts like a pair of Polaroid sunglasses, blocking out glare from thousands of ordinary sources.

After initial detection, We made additional observations over several months using ASKAP Also the most sensitive Meerkat radio telescope in South Africa.

ASKAP belongs to the class J1935+2148 Relatively new long-term radio is unstable. Only two more have been discovered, and ASKAP J1935+2148’s period of 53.8 minutes is the longest.

however, An exceptionally long period is just the beginning. ASKAP looked at J1935+2148 in three different positions or modes.

In the first case, we see bright, linearly (rather than circularly) polarized pulses Lasts from 10 to 50 seconds. In the second stage, there are very weak, circularly polarized pulses. It lasts only about 370 milliseconds. The third stage is the quiet or dull stage, without any pulse.

These different modes and switching between them, They can occur due to complex magnetic fields and the interaction of strong magnetic fields with the plasma flowing from the source and the surrounding space.

Similar patterns are seen in neutron stars. But our current understanding of neutron stars suggests that they cannot have such long lifetimes.

Artistic realization of an FRB. Credit: ESO

The origin of such a long-lived signal remains a deep mystery, a slowly rotating neutron star is the prime suspect. However, we cannot rule out the possibility that the object is a white dwarf: Earth-sized ash that has run out of fuel from a burned-out star.

White dwarfs typically have slow rotation periods. But we don’t know any way to generate the radio signals we see here. What’s more, there are no other highly magnetic white dwarfs nearby, making the neutron star explanation more plausible.

One explanation might be that The object is part of a binary system in which a neutron star or white dwarf orbits another invisible star.

This material Neutron stars or white dwarfs could lead to a rethinking of our decades-old understanding. Especially how they emit radio waves and how their population is in our galaxy. More research is needed to confirm what the material is, but a demonstration will provide valuable information about the physics of these extreme objects.

We do not know how long ASKAP J1935+2148 has been emitting radio signals. Radio astronomy surveys typically do not look for objects with such long periods. Furthermore, radio emissions from this source are only detected at 0.01% to 1.5% of its orbital period, depending on its emission state.

So we were very lucky to be able to see ASKAP J1935+2148. There are likely many similar objects in other parts of our galaxy Waiting to find out.

*Manisha CalebProfessor, University of Sydney

**Emil LenzResearch Scientist, Space and Astronomy, CSIRO

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