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A historic black hole that is seen to shine



Looking at old data, scientists can say that the light region in the ring is moving around
Looking at old data, scientists can say that the light region in the ring is moving

When scientists unveiled the first photo of a black hole last year, it was hailed as an outstanding breakthrough.

Well, now they have released some additional images that have been acquired over the years to the historical photo.

And it gives us some new perspectives on the object known as M87 *, which has a monstrous mass of 6.5 billion suns.

We can see, for example, that the brightness of a black hole flickers over time.

This is probably the result of the fragmentation of M87 * and the consumption of nearby matter caught in the fierce gravity.

Matter heated to billions of degrees twists and turns through intense magnetic fields. And as it does so, the region of brightness observed in the surrounding ring of the black hole gas seems to shake.

“What we see is the flow of matter that revolves around and eventually sinks across the event horizon, but that matter, that flow of plasma and gas, is very turbulent,”

; explains Dr. Maciek Velgus, an astronomer from Harvard University, USA.

“We are expecting this turbulence. There is a so-called magnetic-rotational instability that reverses over this turbulence. And for this reason there is a certain stochasticity (randomness in behavior); brightness spots appear to form in different places,” he told Bi BBC News.

The historical image of M87 *, released in April 2019, was captured by the Event Horizon Telescope (EHT).

A full image cannot be retrieved from the archive data, but some features may
A full image cannot be retrieved from the archive data, but some features may

This is a “virtual observatory”. It connects a series of eight radios – from the South Pole to Hawaii, America and Europe – to mimic the resolution you would get with an Earth-sized telescope.

Astronomers describe the achieved resolution as 42 microarseconds. For the layman, this is visual acuity, which is equivalent to “being able to watch a game of billiards or snooker on the moon, being able to track the movement of balls,” said Dr. Wielgus.

And that’s what you need if you want a detailed view of an object – even one as big as M87 * – that is 53 million light-years (approximately 500 million trillion km) from Earth.

EHT will include more radio equipment over time
EHT will include more radio equipment over time

What we saw last year, scattered on newspapers, websites and television screens, was in the form of a pretzel – the accretion disk, which is a ring of overheated, excited gas that revolves around a dark central region where the black hole is expected to reside.

The picture emerged from a week-long joint observations from the connected EHT array – followed by a long period of computer processing and analysis.

But, of course, to get to this point, there were many years of preparation, trial and error and with fewer radios than in the final EHT configuration.

And these are the data from all the practices that go back to 2009, which Dr. Wielgus and colleagues reviewed and described in an article published in The Astrophysical Journal.

What is a black hole?

  • A black hole is an area of ​​space where matter has collapsed on itself

  • The gravitational pull is so strong that nothing, not even light, can escape

  • Black holes will appear from the explosive doom of some big stars

  • But some are truly gigantic and billions of times the mass of our Sun.

  • How these monsters formed – found in galactic centers – is unknown

  • Black holes are detected by the way they affect their environment

What they have done in essence is to re-evaluate this archive material based on everything they have learned when creating the final image for 2019.

They cannot provide us with whole images from old data, but using models, they can extract details to confirm certain characteristics and behaviors in the M87 * that must have been present in those earlier years.

“None of the older data periods was as good as this one [for the 2019 image], “said Prof. Anton Zensus, director of the Max Planck Institute for Radio Astronomy, Germany.

“But they can all be looked at knowing that there is a basic ring structure there. So if you have limited the initial conditions for looking at this data, then this ring structure is actually obvious in all these sessions, going back to 2009 The significance of this is that we have confirmed [2019] result by looking at older data. “

You need a spectacular resolution to see something so detailed, so far away
You need a spectacular resolution to see something so detailed, so far away

Recognition of a changing brightness position in the accretion disk of M87 * is one of the results of the study.

Another is simply the confirmation of the constancy of the diameter of this ring structure and therefore the diameter of the black hole itself – or rather its event horizon: the area within which the velocity required to avoid gravitational attraction exceeds even the speed of light.

For M87 *, this “surface” is about 40 billion km wide. Think of a space about twice the size of our solar system.

Something else that makes this study gives us an idea of ​​the future potential of EHT.

It logically follows that if you spend many years of data together, it should be possible to make movies about the activity near black holes.

But this will require more radios to be included in the EHT array and the observation periods to be extended.

Currently, EHT operates for only a few days each year in late March, early April, because this is the time of year when the weather is usually good on all the different radio stations around the world.

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos




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