Long-period radio transients (LPTs) are a very recent and still poorly understood class of astrophysical sources. Their particularity is to produce very brief radio bursts, but with an extremely slow repetition: sometimes every tens of minutes, hours, or even days. In recent years, several have been identified, always accidentally, explains Refractor.
Telescopes used by astronomers often operate in a “wide survey” mode of the sky. They collect a large amount of data without focusing on a specific object. Then, scientists analyze these recordings to spot unusual events: this is how BPDs were discovered. To date, astronomers have only identified a dozen, and their exact nature remains to be elucidated.
Recently, in a new study published in Nature Astronomy, scientists describe having detected unprecedented bursts. They named this new source ASKAP J1745. Several telescopes then observed this phenomenon over a wide range of wavelengths, from radio waves to X-rays.
These multispectral data made it possible to identify, for the first time, the nature of this phenomenon. Like the Rosetta Stone, which made it possible to decipher hieroglyphs using several versions of the same text, the new data on ASKAP J1745 could serve as a key to better understanding the mysterious long-period transients.
The dance of two stars
Discovered using the ASKAP radio telescope, operated by the CSIRO (the Australian national science agency), ASKAP J1745 would come from a cataclysmic variable: binary systems composed of two stars, including a white dwarf, orbiting one around the other. When the distance between them is small enough, the white dwarf’s gravity can allow it to attract material from its companion star.
The TPL bursts therefore occur at each orbit of its two stars, that is to say at each complete revolution that the two stars make around each other. This discovery is unique because it provides data that is richer and spans a wider range of wavelengths than any other long-period transient observed before.
The study of the mechanisms at the origin of these bursts offers a new natural laboratory for exploring extreme physical phenomena, such as plasma flows and magnetic fields, in conditions impossible to reproduce on Earth.
“Each new discovery helps us piece together the bigger pictureexplained Kovi Rose, co-author and doctoral student in astrophysics at the University of Sydney in a press release. We are only just beginning to understand this new category of cosmic events.”
