A team of scientists, led by NSF’s Green Bank Observatory (NSF GBO), recently identified a very rare object called the long-term radio Transient (LPT), a very rare object called the Chime J1634+44. These objects resemble Rotating Radio Transients (RRT), the source of short radio pulses thought to be caused by pulsating neutron stars (pulsars). The difference with LPTS is that they have very long spinning periods and often last between minutes and hours. However, chime J1634+44 is the only LPT ever observed, as indicated by reduced spin period and anomalous polarization.
These attributes challenge the current understanding of temporary objects and raise new questions about physics that govern the universe. Nevertheless, the timing of repeated radio bursts from chime J1634+44 is unknown. In a press release from NRAO, Fengqiu Adam Dong, Jansky Fellow of NSF GBO, said:
Among other LPTs, Chime J1634+44 can be called a “unicorn.” The burst appears to be repeated every 14 minutes or every 841 seconds, but there is a clear secondary period of 4206 seconds or 70 minutes, which is exactly five times longer. I think both are real, but this is probably a system that orbits neutron stars.
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In addition to the Green Bank Telescope, additional observations with low frequency observations were made possible using very large arrays (VLAs), the Canadian Hydrogen Strength Mapping Experiments (CHIME) First Radio Burst and Pulsar Project, and NASA’s Neil Garell Swift Observations (SWIFT). The combined capabilities of these telescopes allowed scientists to detect and study abnormal signals in objects in detail.
The wide field of view of the chime detected temporary periodic bursts and monitored spins, but the VLA system of real-time fast transient search using interferometric imaging (aka Realfast) provided high-frequency observations to correct distortions in interstellar media (ISM) and provided more accurate position data. GBT provided high-resolution timing data to analyze polarization and spin, while Swift searched X-ray counterparts and complemented radio observations from other observatory.
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Typically, compact objects, such as neutron stars, lose energy over time, slower spin and longer spin periods. However, when the team observed the chime J1634+44, they discovered that its rotation period was shorter. In other words, LPT must be speeded up. There is no plausible explanation for this happening on a single star, so the team theorizes that it must be part of a binary system that reduces orbit. This can be due to the release of binary pairs or gravitational waves (GWS) that lose energy through gravity interactions.
This behavior was seen in other closely orbiting white dwarfs, creating the illusion that their period was shortened, but we have never found neutron stars to do this on a burst-by-burst basis. Additionally, the radio burst from Chime J1634+44 was moving in perfect swirls as it passed through space. In other words, it is completely circular. This suggests that the way these radio waves are generated is different from what is seen with all other known objects. Don said:
The discovery of Chime J1634+44 suggests that there may be more such objects awaiting discovery, expanding the known population of LPT, challenging existing models of neutron stars and white dwarfs.
These discoveries could pave a new pathway for radio astronomy and help astronomers deal with the mystery of the rotation of neutron stars, one of the most enigmatic objects in the cosmos.
The original version of this article was published today in Universe.
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