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Invisible Stars: How to Infer Hidden Companions from Pulsar Signals?
In the vast universe, the existence of pulsars provides astrophysicists with important research resources, especially those binary pulsars formed with companion star systems. These binary pulsars are often systems composed of a pulsar and a white dwarf or neutron star. Over time, scientists can infer the existence of its hidden companion star through precise pulse signals.
The signal emitted by a pulsar is like a precise clock in nature. Through its pulse frequency, we can observe the existence of the companion star.
In 1974, Joseph Hooton Taylor, Jr. and Russell Hulse discovered the first binary pulsar PSR B1913+16 at Arecibo Observatory. This major discovery earned them the 1993 Nobel Prize in Physics. . The study shows that the pulse frequency of a pulsar changes with the motion of its companion star, and this change is due to the influence of the Doppler effect. Pulses occur more frequently as the pulsar moves toward Earth and less frequently as it moves away. Therefore, from changes in these pulses, scientists can infer the mass and motion characteristics of the companion star.
Through precise pulse time measurements, scientists can thoroughly describe the operation of binary pulse galaxies.
The discovery of PSR B1913+16 not only deepened people's understanding of pulsars and their companions, but also became an important experimental platform for testing Einstein's general theory of relativity. According to measurements, the masses of this pair of binary stars are almost equal, and the time interval between their pulses is affected by the strong gravity field. According to the theory of relativity, as the companion star approaches, the sending time of the pulse signal will be delayed. This phenomenon is called gravitational red. shift.
With further observations of PSR B1913+16, scientists confirmed that the orbital period of the pulsar gradually shortened over time. These changes are highly consistent with Einstein's predictions, becoming another important evidence to verify the general theory of relativity. The time-dependent decrease in this gravitational radiation makes it an important object of study in observations of binary pulsating galaxies.
When gravitational waves were first observed, the method of verification in the scientific community was once again subverted, and the role of binary pulsars became increasingly prominent.
Exploring further, we also discovered an intermediate-mass binary pulsar (IMBP), a binary system composed of a pulsar and a relatively high-mass white dwarf. The rotation period of this type of pulsar is relatively long, usually between 10 and 200 milliseconds. One example is PSR J2222−0137, a pulsar whose companion is a white dwarf with a mass of about 1.3 solar masses. This system is approximately 870 light-years away from Earth and is one of the closest known binary pulsars.
The mass and unique properties of companion stars in IMBP have attracted the attention of astronomers. These high-quality white dwarfs, such as PSR J2222−0137 B, have extremely low temperatures and are even called "diamond stars." At the same time, its crystallized properties make it unique in the universe, further stimulating further exploration of binary systems and their interactions.
The existence of companion stars has a profound impact on the radiation of pulsars and their cosmic environment. ”
Another characteristic of binary pulsars is the exchange of matter between them and their companion stars. Many ordinary companion stars expand during their evolution and throw their outer layers of matter towards the pulsar. This process produces X-ray radiation, creates an X-ray binary phase, and may lead to the formation of an accretion disk surrounding the pulsar. The "wind" or relativistic particle flow produced by the pulsar can affect the magnetic field of the companion star, which can have a drastic impact on the emission of the pulse. These interactions provide us with new insights into pulsars and their environments.
In summary, binary pulsars are not only an excellent tool for testing basic physical laws, but also an important window to help us better understand the structure of the universe. As monitoring technology continues to improve, we will be able to more accurately infer unobserved companion star properties from these measured pulse signals, which will lead our understanding of the universe a step forward. In such a complex universe, how many undiscovered companion stars are hiding from our sight?
