Astronomers are aware of unusual X-ray pulsars that produce streams of energy. The current model cannot explain
A rare object recently discovered by astronomers turns out to be an exploding and accreting millisecond X-ray pulsar, according to a newly published study. The new X-ray pulsar, named SRGAJ144459.2-604207, uses the Astronomical Roentgen Telescope – X-ray Concentrator (ART-XC) aboard the High Energy Astrophysical Observatory Spectrum Roentgen Gamma (SRG) It was discovered. The German-Russian mission, launched in 2019, includes seven Russian-made X-ray telescopes with grazing-incidence mirrors whose mirrors were designed and calibrated by NASA. First observed in February 2024, as the pulsar’s burst phase weakened, a coherent signal of approximately 447.8 Hz modulated by the Doppler effect due to its orbital motion was detected, indicating the presence of a binary star system and an accretion disk. . An accretion disk is a round, rotating body of matter that surrounds a large gravitational body, in this case her X-ray pulsar. “The sustained-emission pulse profile exhibits a sinusoidal portion with a plateau between half-periods and can be well modeled by emission from two circular patches partially obscured by the accretion disk,” said the authors of the study. The research team made a new statement. Sergey V. Morkov of the Space Research Institute in Moscow, Russia. What’s special about X-ray pulsars is that they produce very pronounced periodic fluctuations in the X-ray intensity, some of which last only a fraction of a second. Their short rotation periods result from long-term mass transfer from a low-mass companion star moving through an accretion disk to a slowly moving neutron star. These strange X-ray pulsars exhibit behavior that may be important in understanding thermonuclear explosions and the processes behind them. During observations, Morkov and his research team discovered 19 thermonuclear X-ray bursts emitted by SRGAJ144459.2-604207. Each burst “had similar shape and energy, and there was no sign of an increase in the radius of the photosphere,” the researchers wrote in their paper. Morkov and his research team also noticed that the burst rate decreased linearly at the beginning of the observation and gradually increased toward the end. The research team said that spectral observations of X-ray pulsars that coincided with these outbursts are “consistent with models of accretion-heated neutron star atmospheres,” which range from 3 to 5 kilometers in radius to 11 to 12 kilometers in radius. This suggests that several neutron stars existed at once. The distance from Earth is 27,000 to 35,000 light years.
The researchers were also able to detect pulses that occurred at the same time as the burst, and showed that the pulse profile was significantly different from that observed during sustained exercise. Still, Morkov and his research team report that they were unable to determine the cause of the abnormal pulse profile. “We were unable to find a simple physical model to explain the pulse profile detected during the burst,” the paper’s authors wrote.
The research team’s new paper, “SRG/ART-XC discovery of SRGAJ144459.2-604207: A well-coordinated burst, accreting millisecond X-ray pulsar,” can be read on the preprint website arXiv.org.
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