"Radio signals from aliens" occur in the gas clouds around compact objects.
The international team of astrophysicists has discovered evidence that repeating fast radio bursts (FRBs), unique "alien radio signals," are generated by interactions between hot gas clouds and compact objects, which could be neutron stars known as magnetars and binary X-ray stars, the press service of the National Institute of Astrophysics (INAF) reported.
"We have managed to obtain evidence that constant sources of FRB bursts behave as predicted by the theory, according to which these flashes occur inside a 'bubble' of ionized gas surrounding a compact object. We were able to detect weak radio emission constantly emitted by such an object inside the nearest source of repeating FRB bursts," said INAF researcher Gabriele Bruni, whose words are quoted by the institute's press service.
Bruni made this discovery while observing the repeating source of "alien radio signals" FRB20201124A, which was discovered in November 2020 in the constellation of Taurus. It is located in one of the relatively close galaxies, which is 1.33 billion light-years away from us, allowing it to be observed with a large number of ground-based and orbital telescopes.
In particular, researchers recently conducted a prolonged observation session of this object using the American ground-based radio telescope VLA. The collected data indicated the presence of a barely noticeable point object at the center of the source FRB20201124A, which constantly emitted radio waves at a frequency of 15 GHz. This discovery prompted astrophysicists to observe this object using the GTC optical telescope and to study the spectrum of its radio emission at other frequencies.
The observations conducted by scientists ruled out the possibility that the weak radio emission they recorded originates inside the areas adjacent to the FRB burst, where new stars form. At the same time, the analysis of the level of polarization of radio waves by astrophysicists also indicated that the source of these fluctuations is a giant cloud of hot gas surrounding the point source of radio waves.
The researchers note that two types of compact objects - a magnetar, a young neutron star with an extremely powerful magnetic field, and a binary X-ray star, a combination of a regular luminary and a small black hole - are contenders for this role. Subsequent observations of repeating "alien radio signals" will help understand which of these two types of compact objects actually generates FRB bursts, the astrophysicists said.
About "alien radio signals"
Mysterious FRB bursts were accidentally discovered in 2007 during observations of neutron stars-pulsars at the Parkes Observatory in Australia. They are very short yet powerful radio signals with an unexplained periodic structure, the source of which is located at a tremendous distance from Earth. Astronomers cannot accurately say how FRB bursts occur, and why only a small fraction of them repeat.
