Unknown Structure in Galaxy

                 Artist's impression of a giant galaxy with a high-energy jet. 

Credit: ALMA (ESO/NAOJ/NRAO)

As a result of achieving high imaging dynamic range, a team of astronomers in Japan has discovered for the first time a faint radio emission covering a giant galaxy with an energetic black hole at its center. 

The radio emission is released from gas created directly by the central black hole. The team expects to understand how a black hole interacts with its host galaxy by applying the same technique to other quasars.

3C273, which lies at a distance of 2.4 billion light-years from Earth, is a quasar. A quasar is the nucleus of a galaxy believed to house a massive black hole at its center, which swallows its surrounding material, giving off enormous radiation. 

Contrary to its bland name, 3C273 is the first quasar ever discovered, the brightest, and the best studied. It is one of the most frequently observed sources with telescopes because it can be used as a standard of position in the sky: in other words, 3C273 is a radio lighthouse.

When you see a car's headlight, the dazzling brightness makes it challenging to see the darker surroundings. The same thing happens to telescopes when you observe bright objects. Dynamic range is the contrast between the most brilliant and darkest tones in an image. 

You need a high dynamic range to reveal both the bright and dark parts in a telescope's single shot. ALMA can regularly attain imaging dynamic ranges up to around 100, but commercially available digital cameras would typically have a dynamic range of several thousands. Radio telescopes aren't very good at seeing objects with significant contrast.  READ MORE...

Star Eats Black Hole

 It’s the first firm evidence of a rare cosmic phenomenon

Jets of energy explode from a star that has cannibalized its dead companion
in this artist’s illustration.

For the first time, astronomers have captured solid evidence of a rare double cosmic cannibalism — a star swallowing a compact object such as a black hole or neutron star. 

In turn, that object gobbled the star’s core, causing it to explode and leave behind only a black hole.

The first hints of the gruesome event, described in the Sept. 3 Science, came from the Very Large Array (VLA), a radio telescope consisting of 27 enormous dishes in the New Mexican desert near Socorro. 

During the observatory’s scans of the night sky in 2017, a burst of radio energy as bright as the brightest exploding star — or supernova — as seen from Earth appeared in a dwarf star–forming galaxy approximately 500 million light-years away.

“We thought, ‘Whoa, this is interesting,’” says Dillon Dong, an astronomer at Caltech.

He and his colleagues made follow-up observations of the galaxy using the VLA and one of the telescopes at the W.M. Keck Observatory in Hawaii, which sees in the same optical light as our eyes. 

The Keck telescope caught a luminous outflow of material spewing in all directions at 3.2 million kilometers per hour from a central location, suggesting that an energetic explosion had occurred there in the past.  READ MORE

Dyson Spheres

Technologically-savvy aliens could be powering their society using a hypothetical megastructure called a Dyson sphere to harvest energy from a black hole. And the sphere might radiate in peculiar ways, allowing telescopes on Earth to discover the existence of intelligent beings elsewhere in the universe, a new study suggests.

A Dyson sphere is a speculative structure that would encircle a star with a tight formation of orbiting platforms in order to capture starlight and produce power, according to Live Science's sister site Space.com. First proposed by theoretical physicist Freeman Dyson in 1960, the idea might be realized by a spacefaring extraterrestrial species who had spread out across their star system and therefore required ever-increasing amounts of energy.

During a coffee break, astronomer Tiger Yu-Yang Hsiao of National Tsing Hua University in Taiwan and his colleagues read a paper about Dyson spheres and began wondering if it were possible to build one around a black hole instead of a star.

"Black holes are one of the brightest objects in the sky," Hsiao told Live Science.

While we normally think of them as being dark and all-consuming, black holes can radiate incredible amounts of energy, he added. Material often forms a disk as it falls into a black hole's maw, much like water circling a drain.

As the gas and dust in this disk spin and bump against each other, they heat up through friction, sometimes to millions of degrees, producing light in the X-ray portion of the electromagnetic spectrum, Hsiao said. Colossal beams of energy can also shoot from a black hole's poles.  READ MORE

Hawking's Black Holes Paradox

Netta Engelhardt puzzles over the fates of black holes in her office at 

the Massachusetts Institute of Technology.

In 1974, Stephen Hawking calculated that black holes’ secrets die with them. Random quantum jitter on the spherical outer boundary, or “event horizon,” of a black hole will cause the hole to radiate particles and slowly shrink to nothing. Any record of the star whose violent contraction formed the black hole — and whatever else got swallowed up after — then seemed to be permanently lost.

Hawking’s calculation posed a paradox — the infamous “black hole information paradox” — that has motivated research in fundamental physics ever since. On the one hand, quantum mechanics, the rulebook for particles, says that information about particles’ past states gets carried forward as they evolve — a bedrock principle called “unitarity.” 

But black holes take their cues from general relativity, the theory that space and time form a bendy fabric and gravity is the fabric’s curves. Hawking had tried to apply quantum mechanics to particles near a black hole’s periphery, and saw unitarity break down.

So do evaporating black holes really destroy information, meaning unitarity is not a true principle of nature? Or does information escape as a black hole evaporates? Solving the information paradox quickly came to be seen as a route to discovering the true, quantum theory of gravity, which general relativity approximates well everywhere except black holes.

In the past two years, a network of quantum gravity theorists, mostly millennials, has made enormous progress on Hawking’s paradox. One of the leading researchers is Netta Engelhardt, a 32-year-old theoretical physicist at the Massachusetts Institute of Technology. 

She and her colleagues have completed a new calculation that corrects Hawking’s 1974 formula; theirs indicates that information does, in fact, escape black holes via their radiation. She and Aron Wall identified an invisible surface that lies inside a black hole’s event horizon, called the “quantum extremal surface.” 

In 2019, Engelhardt and others showed that this surface seems to encode the amount of information that has radiated away from the black hole, evolving over the hole’s lifetime exactly as expected if information escapes.  READ MORE

Capturing Black Holes

A German-built space telescope is creating the most detailed map of black holes and neutron stars across our universe, revealing more than 3 million newfound objects in less than two years.

The observatory, called eROSITA, launched in 2019 and is the first space-based X-ray telescope capable of imaging the entire sky. 

It is the main instrument aboard the Russian-German Spectrum-Roentgen-Gamma mission, which sits in a region known as Lagrange point 2, one of five stable points around the sun-Earth system, where the gravitational forces of the two bodies are in balance. 

From this vantage point, eROSITA has a clear view of the universe, which it photographs with its powerful X-ray detecting instruments.

Last month, the team behind eROSITA, led by scientists from the Max Planck Institute for Extraterrestrial Physics in Germany, released the first batch of data acquired by the instrument to the wider scientific community for exploration.  READ MORE