Scientists study a mysterious signal from space that we receive for months every 18 minutes and 18 seconds

A puzzle. What the radio astronomer Natasha Hurley-Walker and his students hunted while combing through the GaLactic and Extragalactic All-Sky MWA eXtended data (GLEAM-X), a great study of the sky carried out with the help of one of the most sensitive radio telescopes on Earth, is just that: a real puzzle for which they still do not have a fully confirmed answer. During their work, the team detected a radio wave in space with regular pulsations. every 18 minutes and 18 seconds. The unusual phenomenon lasted for a period of approximately three months – from January to March 2018 – before disappearing.

Now, Hurley-Walker and her graduate student Tyrone O’Doherty publish an article in Nature with some conclusions. Its goal is to shed light on the source of the signals. At the moment, after assessing the data and discarding work, they point out that the object is located 4,000 light years away and could be a white dwarf —very small and hot stars that represent the last phase in the existence of stars similar to the Sun— with an ultra-strong magnetic field; or a magnetar —a neutron star with a powerful magnetic field— of ultra-long period.

“By measuring the dispersion of the radio pulses with respect to frequency, we have located the source within our own Galaxy and we suggest it could be a magnetar ultra long period ”, point out. Although this last option coincides with the predictions that astronomers had made at a theoretical level, Professor Hurley-Walker, from Curtin University and the International Center for Radio Astronomy Research (ICRAR), recognize that the phenomenon is surprising.

A mystery 4,000 light years away

“No one believed we were going to directly detect one like this because we didn’t expect them to be that bright; somehow it’s converting magnetic energy into radio waves much more efficiently than anything we’ve seen before.” a statement from ICRAR. The team is aware of a white dwarf that emits similar pulses, but it is very different from the phenomenon they have now captured: it is much closer to Earth – about 10 times closer – and it is 100 times fainter than the object it now centers Hurley-Walker’s attention.

What they have verified using the radio telescope Murchison Widefield Array (MWA) from Australia is that the object emitted pulses every 18 minutes and 18 seconds, “an unusual periodicity”, in the words of the researchers themselves, who have no evidence that it has been observed before. The emission also stands out for being very linearly polarized, it is bright, persists for 30-60 seconds at each appearance and is visible over a wide range of frequencies.

“Sometimes the pulses comprise bursts of short duration (<0.5 s); in others, a smoother profile is observed. These profiles evolve on timescales of hours." specifies the article Nature, in which the researchers clarify that they tracked a total of 71 pulses. The observations they have made so far show that the source, named GLEAM-X J162759.5-523504.3, is smaller than the Sun and that when it rotates it emits beams of radiation. Beyond the three-month period in which it was visible – from January to March 2018 – the experts could no longer identify it, neither in the previous nor in the subsequent observations.

Hurley-Walker and her team continue to work with the MWA radio telescope in hopes that the possible magnetar will start emitting signals again. If so, Explain that there are telescopes scattered around the southern hemisphere and in orbit that could point directly at it. Another source of valuable information, and one that they are already working on, is the MWA’s own archives. The goal, the astronomer specifies, is to determine if what they have located is a unique and isolated event or could put them on the track of “a vast new population of objects that we had not detected before”.

What the researchers are clear about is that the more data they accumulate on the episodes that mark the life of the stars, especially in their final stages, the more they will know about the life and death of massive stars. Another phenomenon that could help to understand better are the radio bursts, FRB, for its acronym in English, which still present many doubts for radio astronomers.

Main Image | IS SUN. Sidewalk