Scientists have detected gravitational waves generated from the black hole merger event, which resulted in the black hole settling into a stable, spherical shape. These waves reveal that the combo black hole may be much larger than previously thought.
When first detected on May 21, 2019, a gravitational wave event known as GW190521 was believed to have come from a merger between the two. Black holes, one with a mass equal to 85 Suns and the other with a mass equal to about 66 Suns. Scientists believed that this merger produced about 142 Solar mass The daughter is a black hole.
However, newly studied space-time vibrations from a merging black hole, which ripple outwards when the vacuum is resolved into a perfect sphere, appear to be larger than initially predicted. Instead of having 142 solar masses, calculations suggest that its mass should be equal to 250 times that. the sun.
These results will ultimately help scientists design better experiments General relativity, Albert Einstein1915 theory of Gravity, which first introduced the concept of gravitational waves and black holes. „We’re really exploring a new frontier here,” said theoretical physicist Steven Giddings of the University of California, Berkeley. said in a statement.
Related: How dancing black holes get close enough to merge
Gravitational waves and general relativity
General relativity predicts that objects with mass will distort their very fabric Space And time—united into a single, four-dimensional entity called „spacetime”—and arises from that „gravitational” curve.
Just as a bowling ball placed on a stretched rubber sheet makes a more intense „dent” than a tennis ball, a black hole causes more curvature in space-time than a star, and a star causes more curvature than a planet. In fact, a black hole is, in general relativity, a point of matter that causes the curvature of spacetime to become more extreme, at the boundary Event does not spreadNot even light is fast enough to escape an inward crater.
However, this is not the only revolutionary prediction of general relativity. Einstein also predicted that when objects accelerate, they should set up with ripples called spacetime ringing. Gravitational waves. Again, the larger the objects involved, the more intense the phenomenon. As dense bodies like black holes spin around each other, constantly accelerating due to their circular motion, the spacetime around them hums with gravitational waves, like a struck bell.
These ripples in spacetime carry angular momentum away from the spiral black holes, and this tightens the black holes’ mutual orbits, pulling them together and increasing the frequency of the emitted gravitational waves. Orbiting closer and closer together, the black holes eventually merge to form a daughter black hole, sending high-frequency „chirp” gravitational waves reverberating through the universe.
But there was one thing Einstein misunderstood about gravitational waves. The great physicist believed that these ripples are very faint in space-time. Earth After traveling across the universe For millions or billions of light years.
Still, on Sept. In 2015, double inventors Laser Interferometer Gravitational-Wave Observatory (LIGO) based in Washington and Louisiana showed Einstein wrong. They detected GW150914, the gravitational waves associated with the merging of about 1.3 billion black holes. light years far away. The gravitational wave signal was detected as a change in the length of one of LIGO’s 2.5-mile (4-kilometer) long laser arms, equivalent to one-thousandth of a width. Proton.
Remarkably, since then, LIGO and its fellow gravitational wave detectors, Ganni in Italy and Gagra in Japan, have detected many such events, reaching the point where they detect one gravitational wave event every week. However, even among this cornucopia of gravitational wave detectors, GW190521 stands out.
A special gravitational wave phenomenon
The merger frequency of the two black holes behind the GW190521 signal, located 8.8 billion light-years from Earth, was so low that the frequency rose sufficiently only during the black holes’ final two orbits. LIGO and Virgo will reach their sensitivity limits.
The team behind this new investigation – which is not part of the LIGO/Virgo Collaboration – wants to know what information this signal contains about the violent collision and merger of these black holes.
They found that immediately after the black holes collided, the black hole was formed with a tilted shape. Black holes are stable only when they have a spherical shape, meaning that within milliseconds of convergence, the daughter black hole must assume the shape of a sphere.
Just as the shape of a bell determines the frequency at which it rings, as this new black hole adjusts its shape, the frequencies of the gravitational waves it rings are altered, the team said. These gravitational waves, known as „ringdowns,” carried information about the daughter black hole’s mass and its rotation speed.
Ring-down gravitational waves from such mergers offer scientists an alternative way to measure the properties of merging black holes, as opposed to the traditional method of using gravitational waves generated during spin processes.
The team found two distinct ring-down frequencies in GW190521’s gravitational wave signal, which when considered together give the resulting black hole 250 solar masses. This means that it is much larger than estimated using eddy gravity waves. Finding these ring-down gravitational waves came as a shock to the team behind the findings.
„I don’t think I’ll ever see a measurement like this in my lifetime,” said Radboud University physicist and co-author of the research Padri Krishnan.
The team’s findings are detailed in an article published in the journal Nov. 28 Physical review letters.
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