Black hole

2022 - 5 - 12

Post cover — Image courtesy of "Harvard Gazette"

Second black hole image unveiled, first from our galaxy (Harvard Gazette)

Pioneering Harvard-led global collaborative unveils latest portrait, bolstering understanding of relativity, gravity.

The project will involve designing new ultra-high-speed instrumentation and a plan to double the number of radio dishes in the EHT array that will allow scientists “to create an Earth-sized motion picture camera” that “will bring black holes to vibrant life,” said Doeleman, who also leads the ngEHT project. On Monday at 5:15 p.m. in the Harvard Science Center, Hall C, there will be a special public event with members of Harvard’s EHT team discussing the results. We’re hoping to add these new telescopes around the world and be able to really dig into those sharp features and to be able to see these high-resolution movies.” It also marks a monumental collaborative achievement for the EHT, made up of more than 300 researchers from 80 institutes around the globe and 11 observatories. The averaged image retains features more commonly seen in the varied images and suppresses features that appeared less frequently. “For Sgr A*, you have a toddler running around and you’re trying to get their portrait with the long-exposure camera. M87 is 55 million light-years away in the Virgo Galaxy cluster and has a mass about 6.5 billion times that of our sun. “This material scatters the light that we observe from Sgr A*. It’s like looking at something through frosted glass.” The researchers produced the picture with observations from the Event Horizon Telescope, a worldwide network of radio telescopes that link together to form a single Earth-sized virtual instrument. Sgr A*, on the other hand, is on the small side. The way the light bends around the dark center, known as the event horizon, shows the object’s powerful gravity, which is four million times that of our sun. An international team of astronomers led by scientists at the Center for Astrophysics

Supermassive black hole at centre of Milky Way seen for first time (The Guardian)

Event Horizon telescope captures image giving a glimpse of the turbulent heart of our galaxy.

The EHT picks up radiation emitted by particles within the accretion disc that are heated to billions of degrees as they orbit the black hole before plunging into the central vortex. Some combination of these factors – and possibly some extreme black hole phenomenon – explain the bright blobs in the image. A minority of scientists had continued to speculate about the possibility of other exotic objects, such as boson stars or clumps of dark matter. Markoff compared the observations with trying to photograph a puppy chasing its tail using a camera with a slow shutter speed. The black hole itself, known as Sagittarius A*, cannot be seen because no light or matter can escape its gravitational grip. It’s been a 100-year search for these things and so, scientifically, it’s a huge deal.”

Black hole: First picture of Milky Way monster (BBC News)

Astronomers reveal the first ever image of the black hole at the core of our galaxy.

They'll even be looking to see if there are some star-sized black holes in the region, and for evidence of concentrated clumps of invisible, or dark, matter. What else could produce gravitational forces that accelerate nearby stars through space at speeds of up 24,000km/s (for comparison our Sun glides around the galaxy at a sedate 230km/s, or 140 miles per second)? The mass of a black hole determines the size of its accretion disc, or emission ring. So far, what they see is entirely consistent with the equations set out by Einstein in his theory of gravity, of general relativity. The 'hotspots' you see in the ring move around from day to day." This arrangement enables the EHT to cut an angle on the sky that is measured in microarcseconds.

In a historic first, astronomers capture image of our galaxy's ... (CBC.ca)

In another historic first, astronomers using the Event Horizon Telescope have taken the first image of the Milky Way's supermassive black hole, ...

Nobel Prize-winning astrophysicist Kip Thorne ran calculations on a supercomputer to try to present a realistic vision of what a black hole might look like. "If I have a black hole that has a certain charge, electrical charge, like static electricity and a certain mass, and it's spinning a certain way, it is absolutely indistinguishable from any other black hole. It's thanks to that movie that we got our first real idea of what a black hole might look like. In the case of M87, its black hole is one of the most massive known. Regardless if we'd seen them or not, black holes have long captured the public's imagination. "I think the analogy to dinosaurs, it's not that different," said Pen, who is also a professor at the Canadian Institute for Theoretical Astrophysics at the University of Toronto. "[It's] a little bit like seeing a live dinosaur in your neighbour's backyard: we can't actually touch it yet. "So solving that problem, we can play some games to remove the blurring. However, astronomer and physicist Karl Schwarzschild, who was fighting in the trenches on the German front during the First World War, managed to prove that they could indeed exist. With Sagittarius A*, while closer, it is along the galactic plane, which means the telescopes needed to peer through thick gas, dust and plasma. Creating imaging of the two black holes presented different challenges. Observations of stars near the core showed them orbiting something invisible, which suggested a black hole. The data for both M87 and Sagittarius A* were collected in 2017.

Astronomers peer into Milky Way's core for first-ever image of ... (The Globe and Mail)

An international team of researchers says they have succeeded in their attempt to pierce the dusty veil that conceals the galactic centre from view and have ...

“To have an exciting result to share about our own galaxy’s black hole is sort of a holy grail. In each instance, the resulting image is not an optical photograph but a map of the radio energy emitted by ionized gas around the black holes. At first blush, the image of the M87 black hole and that of the Milky Way look remarkably similar in a side-by-side comparison. “For many of us, Sagittarius A* is the target that got us into this work,” she added. As technology matured, radio astronomers became aware that there were multiple sources of energy at the galactic core, including one particularly strong and compact source dubbed Sagittarius A* (pronounced “Sagittarius A-star”). He discovered that one of those sources tracked with the sky. The results were simultaneously published in a series of six scientific papers in the Astrophysical Journal Letters. Team members said this offers confidence that what they are seeing is physical reality and not an artifact of the imaging process. Also, because the Milky Way’s black hole is smaller, it changes on time scales that make observing it a challenge. That means it looks roughly the same size from Earth’s point of view, which makes it equally accessible to the Event Horizon Telescope. But while the black hole in M87 can be observed from across 55 million light-years of empty intergalactic space, the Milky Way’s black hole is shrouded by layers of dust in the densest part of our galaxy, about 26,000 light-years away. On that occasion the target was a far more distant object – a behemoth with 6.5 billion times the sun’s mass located in the galaxy M87. That image proved possible simply because that black hole is so large – close to the theoretical limit for how big one can get. Their achievement – a scientific tour de force involving co-ordinated observations made at multiple locations followed by years of data processing and analysis – lays bare the most intriguing and exotic object in humanity’s corner of the universe.

This is the first image of the black hole at the heart of the Milky Way (NPR)

"We finally have the first look at our Milky Way black hole, Sagittarius A*," an international team of astrophysicists and researchers from the Event ...

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