- 3303 - BLACKHOLES - and Neutron Star collisions? In 2017, astronomers witnessed their first kilonova. The event occurred about 140 million light-years from Earth and was found wih the appearance of a certain pattern of gravitational waves, or ripples in space-time, washing over Earth.
--------------------- 3303 - BLACKHOLES - and Neutron Star collisions?
- When a blackhole gobbles up a star, it produces a "tidal disruption event." The shredding of the star is accompanied by an outburst of radiation that can outshine the combined light of every star in the blackhole's host galaxy for months, even years.
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- The X-rays emitted by a tidal disruption event known as “J2150” allowed astronomeers to make the first measurements in year 2021 of both the blackhole's mass and spin. This blackhole is of a particular type, an intermediate-mass blackhole.
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- The fact that we were able to catch this blackhole while it was devouring a star offers a remarkable opportunity to observe what otherwise would be invisible. By analyzing the flare astronomers are able to better understand this elusive category of blackholes, which may well account for the majority of blackholes in the centers of galaxies.
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- This flare originated from an encounter between a star and an -intermediate-mass black hole. The intermediate blackhole in question is of particularly low mass, weighing roughly 10,000 times the mass of the sun.
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- Dozens of tidal disruption events have been seen in the centers of large galaxies hosting supermassive black holes, and a handful have also been observed in the centers of small galaxies that might contain intermediate blackholes. However, past data has never been detailed enough to prove that an individual tidal disruption flare was powered by an intermediate blackhole.
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- The centers of almost all galaxies that are similar to or larger in size than our Milky Way host central supermassive blackholes. These blackholes range in size from 1 million to 10 billion times the mass of our sun, and they become powerful sources of electromagnetic radiation when too much interstellar gas falls into their vicinity.
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- The mass of these blackholes correlates closely with the total mass of their host galaxies; the largest galaxies host the largest supermassive blackholes.
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- We know very little about the existence of blackholes in the centers of galaxies smaller than the Milky Way. Despite their presumed abundance, the origins of supermassive blackholes. Intermediate-mass blackholes could be the seeds from which supermassive blackholes grow.
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- The measurement of the blackhole’s spin holds clues as to how blackholes grow, and possibly to particle physics. This black hole has a fast spin, but not the fastest possible spin.
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- The blackhole spin measurement allows astrophysicists to test hypotheses about the nature of dark matter, which is thought to make up most of the matter in the universe. Dark matter may consist of unknown elementary particles not yet seen in laboratory experiments. Among the candidates are hypothetical particles known as “ultralight bosons“.
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- If ultralight bosons exist and have masses in a certain range, they will prevent an intermediate-mass blackhole from having a fast spin. This blackhole is spinning fast and this rules out a broad class of ultralight boson theories.
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- If most dwarf galaxies contain intermediate-mass blackholes, then they will dominate the rate of stellar tidal disruption. By fitting the X-ray emission from these flares to theoretical models, astronomers can conduct a census of the intermediate-mass blackhole population in the universe.
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- Neutron Stars are just not quit big enough to become blackholes. When neutron stars collide they release a flood of elements necessary for life. Just about everything has collided at one point or another in the history of the universe, so astronomers had long figured that neutron stars, superdense objects born in the explosive deaths of large stars smashed together.
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- If a neutron star collision go out with a flash it wouldn't be as bright as a typical supernova, which happens when large stars explode. But astronomers predicted that an explosion generated from a neutron star collision would be roughly a thousand times brighter than a typical nova, so they dubbed it a “kilo nova“.
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- Neutron stars are made of a lot of neutrons, and when you put a bunch of neutrons in a high-energy environment, they start to combine, transform, splinter off and do all sorts of other wild nuclear reaction things.
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- With all the neutrons flying around and combining with each other, and all the energy needed to power the nuclear reactions, kilonovas are responsible for producing enormous amounts of heavy elements, including gold, silver and xenon.
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- Supernovas and kilonovas fill out the periodic table and generate all the elements necessary to make rocky planets ready to host living organisms, you and me.
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- In 2017, astronomers witnessed their first kilonova. The event occurred about 140 million light-years from Earth and was heralded by the appearance of a certain pattern of gravitational waves, or ripples in space-time, washing over Earth.
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- These gravitational waves were detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo observatory, which immediately notified the astronomical community that they had seen the distinct ripple in space-time that could only mean that two neutron stars had collided.
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- Less than 2 seconds later, the Fermi Gamma-ray Space Telescope detected a gamma-ray burst, a brief, bright flash of gamma-rays.
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- Astronomers around the world trained their telescopes, antennas and orbiting observatories at the kilonova event, scanning it in every wavelength of the electromagnetic spectrum.
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- The gravitational wave signals provided an unprecedented glimpse inside the event itself. Between gravitational waves and traditional electromagnetic observations, astronomers got a complete picture from the moment the merger began.
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- That kilonova alone produced more than 100 Earths' worth of pure, solid precious metals, confirming that these explosions are fantastic at creating heavy elements. The gold in your jewelry was forged from two neutron stars that collided long before the birth of the solar system.
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- That wasn't the only reason the kilonova observations were so fascinating. Albert Einstein's theory of general relativity predicted that gravitational waves travel at the speed of light. But astronomers have long been trying to develop extensions and modifications to general relativity, and the vast majority of those extensions and modifications predicted different speeds for gravitational waves.
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- The gravitational wave signal and the gamma-ray burst signal from the kilonova arrived within 1.7 seconds of each other. But that was after traveling over 140 million miles. To arrive at Earth that close to each other over such a long journey, the gravitational waves and electromagnetic waves would have had to travel at the same speed to one part in a million billion.
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- That single measurement was a billion times more precise than any previous observation, and thus wiped out the vast majority of modified theories of gravity.
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- No wonder a third of astronomers worldwide found it interesting. I hope you did too.
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- October 12, 2021 BLACKHOLES - and Neutron Star collisions? 3303
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