Scientists discover first 'intermediate-mass' black hole in massive merger
It's the largest black hole merger ever observed by scientists.
07 September, 2020
Credit: Pixabay
- In 2019, scientists detected gravitational waves that were later determined to come from the merging of two so-called "intermediate-mass" black holes.
- These black holes were thought to exist, but had never been directly observed.
- The discovery sheds new light on how black holes form.
<p>In May 2019, a ripple of gravitational waves passed through Earth after traveling across the cosmos for 7 billion years. The ripple came in four waves, each lasting just a fraction of a second. Although the ancient signal was faint, its source was cataclysmic: the biggest merger of two black holes ever observed.</p><p>It occurred when two mid-sized black holes — 66 and 85 times the mass of our Sun — drifted close together, began spinning around each other and merged into one black hole roughly 142 times the mass of our Sun. </p><p style="margin-left: 20px;">"It's the biggest bang since the Big Bang observed by humanity," Caltech physicist Alan Weinstein, who was part of the discovery team, <a href="https://www.pbs.org/newshour/science/scientists-spot-two-black-holes-merged-into-never-before-seen-size" target="_blank">told</a> The Associated Press.</p><p>A massive bang, sure. But a black hole of this size actually falls within the "intermediate-mass" category, which ranges from about 50 to 1,000 times the mass of our Sun.</p>
Intermediate-mass black holes
<p>Scientists know relatively little about these mid-sized black holes. They've catalogued small black holes only a few times more massive than the Sun, as well as supermassive black holes more than six billion times the mass of our star. But direct evidence of intermediate-mass black holes has remained elusive.</p><p style="margin-left: 20px;">"Long have we searched for an intermediate-mass black hole to bridge the gap between stellar-mass and supermassive black holes," Christopher Berry, a professor at Northwestern University's Center for Interdisciplinary Exploration and Research in Astrophysics), <a href="https://news.northwestern.edu/stories/2020/09/scientists-detect-first-of-its-kind-intermediate-mass-black-hole-gravitational-waves/" target="_blank">told</a> Northwestern Now. "Now, we have proof that intermediate-mass black holes do exist."</p><p>Still, how these middleweight black holes form is a mystery. Scientists know that smaller black holes form when stars explode in violent events called supernovas. But mid-sized black holes couldn't form this way, according to current physics, because stars of a certain mass range undergo a death process called pair instability, where they explode and leave nothing behind, not even a black hole.</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzczMTI3MC9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTY1NzA4OTU2MH0.vU_L8bVABnteqgu83LOUylGMXSkbx4T2iUIO1anTc5I/img.png?width=980" id="cd591" class="rm-shortcode" data-rm-shortcode-id="631984c49d6189b4adc5f16960abb723" data-rm-shortcode-name="rebelmouse-image" alt="LIGO-Virgo" data-width="1172" data-height="956" />
This chart compares the mass of black-hole merger events observed by LIGO-Virgo.
<p>As for supermassive black holes? Scientists are pretty sure that these behemoths, which lie in the center of most galaxies, <a href="https://www.space.com/giant-gas-halos-fed-black-holes-cosmic-dawn.html#:~:text=At%20the%20cosmic%20dawn%2C%20black,gobbling%20up%20gas%20for%20breakfast.&text=Therefore%2C%20observing%20the%20halos%20of,universe%2C%20according%20to%20the%20statement." target="_blank">grow huge by gobbling up ancient dust, gas</a> and other cosmic matter — including other black holes. Intermediate black holes may form in a similar way, by small-ish black holes repeatedly merging together.</p><p>In other words, an intermediate black hole might be on its way to becoming supermassive.</p><p style="margin-left: 20px;">"We're talking here about a hierarchy of mergers, a possible pathway to make bigger and bigger black holes," Martin Hendry, a professor of gravitational astrophysics and cosmology at Glasgow University, <a href="https://www.bbc.com/news/science-environment-53993937" target="_blank">told</a> the BBC. "So, who knows? This 142-solar-mass black hole may have gone on to have merged with other very massive black holes — as part of a build-up process that goes all the way to those supermassive black holes we think are at the heart of galaxies."</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzczMTU0OS9vcmlnaW4uZ2lmIiwiZXhwaXJlc19hdCI6MTYyNzYyMzcxNX0.x-N4TZ6grQaOVZpoVque4xHinn3IsuUkR4HgAT5VUaU/img.gif?width=980" id="abbfa" class="rm-shortcode" data-rm-shortcode-id="3d0b1fdad7ab3999e55a6f54a296dead" data-rm-shortcode-name="rebelmouse-image" alt="Black hole" data-width="1040" data-height="600" />
Visualization of a black hole.
Credit: NASA
<p>The recent discovery sheds light on how black holes form, but questions still remain. Scientists with the LIGO-Virgo collaboration hope to continue studying the newly discovered intermediate black hole — dubbed GW190521 — in 2021 when the facilities will be up and running again with improved instruments.</p><p style="margin-left: 20px;">"Our ability to find a black hole a few hundred kilometers-wide from half-way across the Universe is one of the most striking realizations of this discovery," Karan Jani, an astrophysicist with LIGO <a href="https://themalaysianreserve.com/2020/09/04/mysterious-intermediate-mass-black-hole-found/" target="_blank">told</a> The Malaysian Reserve.</p><p>The discovery was described in two papers published in the<a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.101102" target="_blank" rel="noopener noreferrer"> Physical Review Letters</a> and <a href="https://iopscience.iop.org/article/10.3847/2041-8213/aba493" target="_blank" rel="noopener noreferrer">The Astrophysical Journal Letters</a>.</p>
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Astrophysicists discover exotic merger of black holes
Gravitational wave researchers observe black holes of different sizes colliding for the first time.
21 April, 2020
Simulation of two black holes of different size orbiting each other, while emitting gravitational waves. Blue colors are weaker gravitational radiation and red is stronger.
- Gravitational wave researchers at LIGO and Virgo observatories spot black holes of different sizes colliding.
- The finding is unusual because previous black hole mergers involved partners of similar size.
- The new information re-confirms Einstein's theory of relativity.
<p>Gravitational wave researchers discovered a very unusual merger of black holes 2.4 billion light-years away. They spotted a collision where one black hole was almost four times larger than another, expanding our understanding of such space cataclysms with help from Einstein (and even Elvis). </p><p><span style="background-color: initial;">All mergers detected previously involved partners of comparable sizes. The event detected on April 12th, 2019 </span><span style="background-color: initial;">was called "exceptional" by <strong>Maya Fishbach</strong>, an astrophysicist at the University of Chicago in Illinois. What she and her colleagues found proves that very unevenly matched black hole pairs exist. </span><span style="background-color: initial;">"This is the first event in which we can confidently say the mass-ratio is not one," she stated during an <a href="https://aps-april.onlineeventpro.freeman.com/" target="_blank">online meeting</a> of the </span><span style="background-color: initial;">American Physical Society.</span></p>
<p>The research was carried out in collaboration between the <a href="https://www.ligo.caltech.edu/" target="_blank">Laser Interferometer Gravitational-Wave Observatory (LIGO) </a>— twin detectors in Washington and Louisiana — as well as the <a href="http://www.virgo-gw.eu/" target="_blank">Virgo observatory</a> near Pisa, Italy. They both detected the merger. One of the black holes observed was <strong>30 times</strong> more massive than the sun and was spinning, said the scientists, while the other had a mass about <strong>eight times</strong> that of the sun.</p><p>In an amusing note, the scientists say that the very different masses created gravitational waves at multiple frequencies, which were actually in harmony with an Elvis Presley song. This cosmic music also confirms yet again Einstein's theory of general relativity.</p><p>Normally, two spiraling black holes of the same size would emit a single frequency, which would be double the rate at which they are orbiting one another, <a href="https://www.sciencemag.org/news/2020/04/gravitational-waves-reveal-unprecedented-collision-heavy-and-light-black-holes" target="_blank">explains</a> Science Magazine. In this case, as predicted by Einstein, the very different masses, also produce <em>overtones</em> - weaker waves at higher frequencies. And if you were to transpose these frequencies to piano notes and intervals, you would get the beginning of Presley's classic <a href="https://www.youtube.com/watch?v=GSaxhqJG1Mw" target="_blank">"I Can't Help Falling in Love with You."</a></p>
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="6d39fce73ed34887a5eaf59a812c34ca"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/GSaxhqJG1Mw?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
<p>The scientists hope that this uniqueness of the detected event could help provide more information about how black holes form. Of special interest is how the variation in mass could have arisen. Under one scenario, the pair could be the result of two massive stars who were orbiting each other, collapsing into black holes. Under another theory, the black holes could have formed independently and found each other in dense star clusters.</p><p>You can read more of the new findings on the <a href="https://arxiv.org/abs/2004.08342" target="_blank">arXiv preprint server.</a></p>
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Astrophysicists discover why black holes and neutron stars shine bright
Researchers find what causes the glow coming from the densest objects in our universe.
29 November, 2019
Credit: NASA, ESA, J. Hester (Arizona State University)
- Columbia University astrophysicists discovered the cause of the unusual glow coming from regions of space with black holes and neutron stars.
- The researchers ran some of the largest computer simulations ever to reach their conclusions.
- They found that turbulence and reconnection of super-strong magnetic fields are responsible for the light.
<p><br></p></div>
<p>Demonstrating again that space is a limitless reservoir of scientific wonders, a new study discovered why areas hosting black holes and neutron stars emit strange bright glows. Astrophysicists found that <strong>turbulence</strong> and <strong>reconnection of super-strong magnetic fields</strong> are behind the cosmic mystery.</p><p>The cause of the phenomenon, which illuminates these super-dense parts of space, has been attributed previously to high-energy electromagnetic radiation. Scientists speculated that it's created by electrons moving at just about the speed of light. The new study from researchers at Columbia University explained why these particles accelerate.</p><p>Astrophysicists <a href="https://lucacomisso.com/about/" target="_blank">Luca Comisso</a> and <a href="http://user.astro.columbia.edu/~lsironi/Site/Home.html" target="_blank">Lorenzo Sironi</a> carried out the research by running some of the largest super-computer simulations ever conducted in this area. They managed to calculate the trajectories of hundreds of billions of charged particles.</p>
<p>Comiso, a postdoctoral research scientist at Columbia, explained their conclusion:</p><p style="margin-left: 20px;">"Turbulence and magnetic reconnection—a process in which magnetic field lines tear and rapidly reconnect—conspire together to accelerate particles, boosting them to velocities that approach the speed of light," said Comisso in a <a href="https://news.columbia.edu/news/black-holes-neutron-stars" target="_blank">press release</a>. </p><p>As Comiso further described, the space region that is home to black holes and neutron stars is also full of a super-hot gas of charged particles. Their chaotic motion affects magnetic field lines and results in "vigorous magnetic reconnection". This, in turn, creates an electric field which accelerates particles to energies that are "much higher than in the most powerful accelerators on Earth, like the Large Hadron Collider at CERN," added Comisso.</p>
Amazing astronomy: How neutron stars create ripples in space-time
<div class="rm-shortcode" data-media_id="skGLOb3j" data-player_id="FvQKszTI" data-rm-shortcode-id="4181b5782ae4c412ce8a339ea70571ff"> <div id="botr_skGLOb3j_FvQKszTI_div" class="jwplayer-media" data-jwplayer-video-src="https://content.jwplatform.com/players/skGLOb3j-FvQKszTI.js"> <img src="https://cdn.jwplayer.com/thumbs/skGLOb3j-1920.jpg" class="jwplayer-media-preview" /> </div> <script src="https://content.jwplatform.com/players/skGLOb3j-FvQKszTI.js"></script> </div><p>Interestingly, the simulations showed that the particles gathered most of their energy through the process of random bouncing at super-high speeds.</p><p style="margin-left: 20px;">"This is indeed the radiation emitted around black holes and neutron stars that make them shine, a phenomenon we can observe on Earth," said Sironi, the study's principal investigator and an assistant professor of astronomy at Columbia.</p><p>Next, the scientists plan to confirm their findings by comparing them to the electromagnetic spectrum from the Crab Nebula, a bright remnant of a supernova. </p><p>You can check out the study published in the December issue of <a href="https://iopscience.iop.org/article/10.3847/1538-4357/ab4c33" target="_blank"><em>The Astrophysical Journal</em></a><em>.</em></p>
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjExMzI3My9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyMDA3MTU2Mn0.ESRk0s8UeKMmTIIRY_iBz6LSM7pNLKbhg1egqx_o79A/img.jpg?width=980" id="ab685" class="rm-shortcode" data-rm-shortcode-id="b47a1d1e3159133ec95b8a6225669f77" data-rm-shortcode-name="rebelmouse-image" />
A massive super-computer simulation demonstrates the strong particle density fluctuations that happen in the extreme turbulent environments home to black holes and neutron stars. The dark blue regions are low particle density regions, and the yellow regions are over-dense regions. Particles are accelerated to extremely high speeds from interacting with turbulence fluctuations.
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