The nature of the twisting of the fabric of space-time in the cosmic "whirlpool" around the dead star made it possible to once again confirm the predictions of Einstein's General Theory of Relativity, according to a new study.
This prediction is a phenomenon known as the entrainment of inertial frames of reference (IRF), or the Lense-Thirring effect. According to him, space-time in the vicinity of massive rotating objects also begins to rotate. For example, imagine that the rotating Earth is immersed in viscous honey. When the planets rotate, the nearby layers of honey are twisted together with it into a funnel - and something similar happens with the space-time continuum.
Previous studies have shown that the Lense-Thirring effect manifests itself in the case of the Earth, but its magnitude is extremely small, and therefore difficult to measure. More massive objects with stronger gravitational fields, such as white dwarfs and neutron stars, are characterized by a measurable IFR effect.
In the new work, researchers led by Vivek Venkatraman Krishnan, an astrophysicist at the Max Planck Institute for Radio Astronomy, Germany, studied a young pulsar called PSR J1141-6545, which has a mass of about 1.27 solar masses and is located at a distance from 10,000 to 25,000 light-years from Earth in the direction of the constellation Mucha. Pulsars are rapidly rotating neutron stars that emit radio waves along the magnetic poles.
Pulsar PSR J1141-6545 revolves around a white dwarf with a mass approximately equal to that of the Sun. White dwarfs are remnants of burnt-out medium-mass stars that have used up their stellar fuel reserves.
The pulsar revolves around a white dwarf in a narrow orbit with a period of less than 5 hours, moving through space at a speed of about 1 million kilometers per hour, with a maximum distance between stars approximately equal to the diameter of the Sun.
Researchers have studied the nature of the pulsar pulses observed from Earth to within 100 microseconds over a period of about 20 years using the Parkes and UTMOST radio telescopes located in Australia. This made it possible to identify long-term changes in the nature of the orbital motion of the pulsar and the white dwarf.
After excluding all other possible causes, the scientists came to the conclusion that these changes represent a manifestation of the IRF dragging effect: the nature of the impact of the rapid rotation of the white dwarf on the surrounding space-time causes a slow change in the orientation of the pulsar's orbit. After assessing the depth of the ISO dragging effect, the researchers calculated that the white dwarf rotates around its own axis at a frequency of about 30 times per hour. The results obtained allowed us to confirm the earlier hypothesis about the origin of the PSR J1141-6545 system, according to which the supernova explosion that formed the pulsar occurred later than the white dwarf was formed; therefore, the material erupted as a result of this stellar explosion caused a significant increase in the rotation speed of the white dwarf.
The research is published in the journal Science.