An animal is hidden in the middle of the galaxy, and it is barely moving.
This supermassive black hole, Sagittarius A * (SGRA *), is 15.1 million times larger than our Sun. It first revealed itself to scientists as a mysterious source Radio waves Back from the center of the galaxy in 1931; But it wasn’t until 2002 that researchers confirmed that radio waves were coming from something as big and compact as a black hole – a feat that got them to 2020. Nobel Prize in Physics. Oct. Just a few days before the team learned about their Nobel on On, another group learned something new about black holes: they rotate more slowly than a supermassive black hole, moving at speeds of less than 10% (probably much less). . Light.
Black holes, despite their incredible power, are extraordinarily simple objects. All the peculiarities of matter that form and feed them are lost in their infinite uniformity. So every black hole in the galaxy can only be described with three numbers: mass, spin and charge.
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Once researchers find a black hole in space, the mass measurement is fairly straightforward – just check how its mass pulls its mass on nearby objects. To obtain the mass of SGRA *, scientists observed its influence on the “S-Stars”, a collection of galactic interstellar stars that accelerate at incredible speeds, whipping around a black hole in orbit. And researchers assume that, like most large black objects in space, black holes do not have strong electromagnetic charges.
(Planet Earth, for example, has some positively charged particles and some negatively charged particles, but they cancel each other out all over the planet. Other planets and known stars work the same way. Researchers believe that black holes do the same. Is neutral.))
It leaves spin as a measurable feature of the rest of the SGRA *, and now researchers believe they have evidence that the supermassive is an unusually slow spinner.
Spin matters for two main reasons.
First, such as Living science previously reported, Black Horse Event Horizon – The shadows within which even light cannot escape the monster Gravity —— increases as it gains more mass, reaching further and further away from the loneliness of black holes. But as the black hole spins faster and faster, the event horizon shrinks. Spinning black holes very quickly should have smaller event horizons than slow-moving black holes of the same mass.
Second, the matter of spin is believed to play a role in two white-hot jets that sometimes enter space at an incredible speed from the axis of rotation of a black hole. Most galaxy-sized galaxies have supermassive black holes at their center, and often these galaxies appear in abundant planes bursting from their cores.
But the galaxy has no visible jets. This suggests that SGRA * may not be moving very fast. Researchers believe that the fast-spinning black hole stimulates the disk to raise objects moving beyond its event horizon, and accelerates some of them to explode as jets. What scientists know about quiet scientists * suggests that they have either an action disc, rarely rotating, or both.
In the new paper, a team of researchers attempted to measure the spin of SGRA *. Once again, they rely on visible S-stars to figure out what their big dark allies do.
Now, researchers have discovered the S-Stars circle SgrA * on two orbital planes. If you want to draw their orbits around a black hole and look at the system from the side, they make an X. SGRA * should be rotating at less than 10% of the speed of light, they found, because no rapid movement would have knocked the S-Stars out of their X-shaped orbital planes by now.
That’s because the orbit, the researchers wrote, is probably as old as the S-stars. The stars still follow the orbits born with them. If SGRA * was spinning too fast, that would not be the case.
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When heavy objects spin very fast in space, that spin affects anything in orbit around them. Over time, those larger objects tug on the orbits of those smaller objects, increasingly connecting them to their own direction of rotation of the rotating object object. The spin is slower, the effect is weaker and it takes longer for the objects to orbit around their hefty core.
The stars are so old that the spin should tug at them significantly if they were too strong. With their orbits similar to their birthdays, the S-stars strongly indicate the upper speed limit for SGRA * at only one tenth of the speed of light. And it will be rotating very slowly.
This result also explains why the SGRA * does not look like a visible jet, they wrote. “The first close-up image of SGRA * ‘s shadow, which is expected to be followed by another research team in the near future, will help confirm this,” he wrote.
This paper was published October 1 Astrophysical Journal Letters.
Published on Original Living Science.