Черная дыра в системе MAXI J1820 + 070 выбрасывает материал в космос

Астрономы обнаружили черную дыру, швыряющую горячий материал в космос со скоростью, близкой к скорости света. Эта вспышка была запечатлена рентгеновской обсерваторией Чандра НАСА. Черная дыра и ее спутник составляют систему MAXI J1820 + 070, расположенную в нашей галактике на расстоянии около 10 000 световых лет от Земли. Черная дыра в MAXI J1820 + 070 имеет массу, примерно в восемь раз превышающую массу Солнца, идентифицируя ее как так называемую черную дыру звездной массы, образованную в результате разрушения массивной звезды. (Это в отличие от сверхмассивных черных дыр, которые в миллионы или миллиарды раз превышают массу Солнца.) Звезда - спутник, вращающийся вокруг черной дыры, имеет массу около половины массы Солнца. Сильная гравитация черной дыры вытягивает материал от звезды-компаньона в диск, окружающий черную дыру. В то время как часть горячего газа в диске пересечет «горизонт событий» (точка невозврата) и упадет в черную дыру, другая часть его материала оторвется от черной дыры в паре коротких пучков материала или джетов. Эти струи направлены в противоположные стороны и запускаются извне горизонта событий вдоль линий магнитного поля. Насколько быстро движутся материальные струи от черной дыры? С точки зрения Земли это выглядит так, как будто северная струя движется со скоростью 60% от скорости света, а южная - с невероятной 160% скорости света!

Это пример сверхсветового движения, явления, которое происходит, когда что-то движется к нам со скоростью света вдоль направления, близкого к нашей линии обзора. Это означает, что объект движется к нам почти так же быстро, как и свет, который он генерирует, создавая иллюзию, что движение струи происходит быстрее, чем скорость света. В случае MAXI J1820 + 070 южная струя направлена ​​на нас, а северная струя направлена ​​от нас, поэтому южная струя движется быстрее северной. Фактическая скорость частиц в обеих струях превышает 80% скорости света.

MAXI J1820 + 070 также наблюдался на радиоволнах командой во главе с Джо Брайтом из Оксфордского университета, который ранее сообщал об обнаружении сверхсветового движения компактных источников на основе одних только радиоданных.

Поскольку наблюдения Чандры примерно вдвое увеличивали продолжительность наблюдения за джетами, объединенный анализ радиоданных и новых данных от Чандры дал больше информации о джетах. Это включало свидетельство того, что джеты замедляются по мере удаления от черной дыры.

Большая часть энергии в струях не преобразуется в излучение, а вместо этого выделяется, когда частицы в струях взаимодействуют с окружающим материалом. Эти взаимодействия могут быть причиной замедления джетов. Когда струи сталкиваются с окружающим материалом в межзвездном пространстве, возникают ударные волны - похожие на звуковые удары, вызванные сверхзвуковым самолетом. Этот процесс генерирует энергии частиц, которые выше, чем у Большого адронного коллайдера.

Исследователи подсчитали, что около 180 тысяч миллиардов тонн материала было выброшено черной дырой в этих двух струях, запущенных в июле 2018 года. Это количество массы сопоставимо с тем, что может быть накоплено на диске вокруг черной дыры в пространстве за несколько часов, и это эквивалентно примерно тысяче комет Галлея.

Исследования MAXI J1820 + 070 и подобных систем обещают рассказать нам больше о струях, создаваемых черными дырами звездной массы, и о том, как они выделяют свою энергию, когда их струи взаимодействуют с окружающей средой.

Under pressure, black holes feast

A new, Yale-led study shows that some supermassive black holes actually thrive under pressure. It has been known for some time that when distant galaxies --and the supermassive black holes within their cores - aggregate into clusters, these clusters create a volatile, highly pressurized environment. Individual galaxies falling into clusters are often deformed during the process and begin to resemble cosmic jellyfish. Curiously, the intense pressure squelches the creation of new stars in these galaxies and eventually shuts off normal black hole feeding on nearby interstellar gas. But not before allowing the black holes one final feast of gas clouds and the occasional star. The researchers also suggested this rapid feeding might be responsible for the eventual lack of new stars in those environments. The research team said "outflows" of gas, driven by the black holes, might be shutting off star formation. "We know that the feeding habits of central supermassive black holes and the formation of stars in the host galaxy are intricately related. Understanding precisely how they operate in different larger-scale environments has been a challenge. Our study has revealed this complex interplay," said astrophysicist Priyamvada Natarajan, whose team initiated the research. Natarajan is a professor of astronomy and physics in Yale's Faculty of Arts and Sciences. The study is published in the Astrophysical Journal Letters. The first author is Angelo Ricarte, a former member of Natarajan's lab now at Harvard, who started this work as a Yale doctoral student. Co-authors are Yale Center for Astronomy and Astrophysics Prize postdoctoral associate Michael Tremmel and Thomas Quinn of the University of Washington.

The new study adds to a significant body of work from Natarajan's research group regarding how supermassive black holes form, grow, and interact with their host galaxies in various cosmic environments.

The researchers conducted sophisticated simulations of black holes within galaxy clusters using RomulusC, a cosmological simulation that Tremmel, Quinn and others developed.

Ricarte developed new tools for extracting information from RomulusC. While analyzing black hole activity in the cluster simulation, he said, he noticed "something weird happening once their host galaxies stopped forming stars. Surprisingly, I often spotted a peak in black hole activity at the same time that the galaxy died."

That "peak" would be the black hole's big, final feast, under pressure.

Tremmel said that "RomulusC is unique because of its exquisite resolution and the detailed way in which it treats supermassive black holes and their environments, allowing us to track their growth."

"Танцующая звезда" вокруг черной дыры

Астрономы из коллаборации GRAVITY зафиксировали в космосе необычное явление: звезду, вращающуюся по траектории розетки вокруг сверхмассивной черной дыры в центре Млечного Пути.Об этом говорится в сообщении пресс-службы Европейской южной обсерватории (ESO VLT). Как передает ведомство, траектория движения звезды подтвердила теорию относительности Альберта Эйнштейна. "Общая теория относительности Эйнштейна предсказывает, что связанные орбиты одного объекта вокруг другого не замкнуты, как в ньютоновской гравитации, а прецессируют вперед в плоскости движения", — сказал директор Института внеземной физики имени Макса Планка Рейнхард Гензел, который руководит исследованием. По его словам, впервые такой эффект наблюдали на орбите планеты Меркурий вокруг Солнца. Теперь же такой эффект виден возле черной дыры "Стрелец А". Звезда, которая вращается вокруг черной дыры, называется S2. Она находится в менее чем 20 млрд км от дыры и завершит орбиту вокруг нее в течение 16 земных лет.

Astronomers detect biggest explosion in the history of the Universe

Scientists studying a distant galaxy cluster have discovered the biggest explosion seen in the Universe since the Big Bang. The blast came from a supermassive black hole at the centre of a galaxy hundreds of millions of light-years away. It released five times more energy than the previous record holder. Professor Melanie Johnston-Hollitt, from the Curtin University node of the International Centre for Radio Astronomy Research, said the event was extraordinarily energetic. "We've seen outbursts in the centres of galaxies before but this one is really, really massive," she said. "And we don't know why it's so big. "But it happened very slowly--like an explosion in slow motion that took place over hundreds of millions of years." The explosion occurred in the Ophiuchus galaxy cluster, about 390 million light-years from Earth. It was so powerful it punched a cavity in the cluster plasma--the super-hot gas surrounding the black hole. Lead author of the study Dr Simona Giacintucci, from the Naval Research Laboratory in the United States, said the blast was similar to the 1980 eruption of Mount St. Helens, which ripped the top off the mountain. "The difference is that you could fit 15 Milky Way galaxies in a row into the crater this eruption punched into the cluster's hot gas," she said. Professor Johnston-Hollitt said the cavity in the cluster plasma had been seen previously with X-ray telescopes. But scientists initially dismissed the idea that it could have been caused by an energetic outburst, because it would have been too big.

"People were sceptical because the size of outburst," she said. "But it really is that. The Universe is a weird place."

The researchers only realised what they had discovered when they looked at the Ophiuchus galaxy cluster with radio telescopes.

"The radio data fit inside the X-rays like a hand in a glove," said co-author Dr Maxim Markevitch, from NASA's Goddard Space Flight Center.

"This is the clincher that tells us an eruption of unprecedented size occurred here."

The discovery was made using four telescopes; NASA's Chandra X-ray Observatory, ESA's XMM-Newton, the Murchison Widefield Array (MWA) in Western Australia and the Giant Metrewave Radio Telescope (GMRT) in India.

Professor Johnston-Hollitt, who is the director of the MWA and an expert in galaxy clusters, likened the finding to discovering the first dinosaur bones.

"It's a bit like archaeology," she said.

"We've been given the tools to dig deeper with low frequency radio telescopes so we should be able to find more outbursts like this now."

The finding underscores the importance of studying the Universe at different wavelengths, Professor Johnston-Hollitt said.

"Going back and doing a multi-wavelength study has really made the difference here," she said.

Professor Johnston-Hollitt said the finding is likely to be the first of many.

"We made this discovery with Phase 1 of the MWA, when the telescope had 2048 antennas pointed towards the sky," she said. "We're soon going to be gathering observations with 4096 antennas, which should be ten times more sensitive."

"I think that's pretty exciting."

What Are Black Holes?

A black hole is an astronomical object with a gravitational pull so strong that nothing, not even light, can escape it. A black hole's "surface," called its event horizon, defines the boundary where the velocity needed to escape exceeds the speed of light, which is the speed limit of the cosmos. Matter and radiation fall in, but they can't get out. Two main classes of black holes have been extensively observed. Stellar-mass black holes with three to dozens of times the Sun's mass are spread throughout our Milky Way galaxy, while supermassive monsters weighing 100,000 to billions of solar masses are found in the centers of most big galaxies, ours included. Astronomers suspect there's an in-between class called intermediate-mass black holes, weighing 100 to more than 10,000 solar masses, but they have not been conclusively observed to date. A stellar-mass black hole forms when a star with more than 20 solar masses exhausts the nuclear fuel in its core and collapses under its own weight. The collapse triggers a supernova explosion that blows off the star's outer layers. But if the crushed core contains more than about three times the Sun's mass, no known force can stop its collapse to a black hole. The origin of supermassive black holes is poorly understood, but we know they exist from the very earliest days of a galaxy's lifetime. Once born, black holes can grow by accreting matter that falls into them, including gas stripped from neighboring stars and even other black holes.

In 2019, astronomers using the Event Horizon Telescope (EHT) - an international collaboration that networked eight ground-based radio telescopes into a single Earth-size dish - captured an image of a black hole for the first time.

It appears as a dark circle silhouetted by an orbiting disk of hot, glowing matter. The supermassive black hole is located at the heart of a galaxy called M87, located about 55 million light-years away, and weighs more than 6 billion solar masses. Its event horizon extends so far it could encompass much of our solar system out to well beyond the planets.

Another first related to black holes came in 2015 when scientists first detected gravitational waves, ripples in the fabric of space as predicted a century earlier by Albert Einstein's general theory of relativity.

The waves were observed at the National Science Foundation's Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington. Their source was the merger of two orbiting black holes that spiraled into each other 1.3 billion years ago. Since then, LIGO and other facilities have observed numerous black hole mergers via the gravitational waves they produce.

These are exciting new methods, but astronomers have been studying black holes through the various forms of light they emit for decades. Although light can't escape a black hole's event horizon, the enormous tidal forces in its vicinity cause nearby matter to heat up to millions of degrees and emit radio waves and X-rays.

Some of the material orbiting even closer to the event horizon may be hurled out, forming jets of particles moving near the speed of light that emit radio, X-rays and gamma rays. Jets from supermassive black holes can extend hundreds of thousands of light-years into space.

NASA's Hubble, Chandra, Swift, NuSTAR, and NICER space telescopes, as well as other missions, continue to take the measure of black holes and their environments so we can learn more about these enigmatic objects and their role in the evolution of galaxies and the universe at large.

See our Black Hole Gallery for additional images, simulations and visualizations about black holes.