Using the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope, researchers have detected a rare type of long-period radio transient, dubbed CHIME J1634+44, that emits powerful, circularly polarized radio bursts every 84 hours.
This discovery, detailed in a July 15, 2025, research paper on arxiv.org, hints at an unusual object, possibly a neutron star or a white dwarf binary behaving in ways that challenge current theories. Unlike typical pulsars, which pulse every few seconds, CHIME J1634+44 belongs to a class called Long Period Radio Transients (LPTs). These objects emit bursts over much longer timescales, from tens of seconds to hours.
What makes this source stand out is its 100% circular polarization, a rare feature where the radio waves oscillate in a circular pattern, detected strongly in one polarization type by the Karl G. Jansky Very Large Array (VLA). This polarization suggests the bursts come from a highly magnetized environment, but the exact mechanism remains a puzzle.
The team, led by researchers from institutions like MIT and Caltech, first spotted the signal on October 31, 2022, with subsequent bursts observed occasionally over the next year. The source’s period is shortening, or “spinning up,” at a significant rate, which is unusual for such objects.
Typically, rotating celestial bodies lose energy and slow down. The researchers propose that CHIME J1634+44 could be part of a binary system, possibly two white dwarfs or a white dwarf and a neutron star, where gravitational wave emission drives this acceleration. Their calculations suggest a merger might occur in about 1.1 million years, a blink in cosmic terms.
Located within our Milky Way, as indicated by its low dispersion measure, CHIME J1634+44 emits bursts far more energetic than similar systems like AR Scorpii, ruling out some white dwarf models. Its quasi-periodic bursts, occurring roughly every 0.13 seconds within a single burst, don’t align with patterns seen in typical neutron stars.
Observations from the Swift telescope found no X-ray or ultraviolet counterparts, suggesting the source’s emissions are primarily radio-based.
As telescopes like CHIME and the VLA continue to scan the skies, scientists hope to uncover more clues about these strange radio signals that are reshaping our understanding and previous theories.
