Astro Blog

By Daniel Clery , Science.  Excerpt: Unusual radio signals could be long-sought smoking gun of galactic mergers. Astronomers routinely see galaxies crashing into each other and combining. But the final phase of these cosmic mergers has long proved elusive: two supermassive black holes, each once occupying the center of its own galaxy, closely circling each other within a single, combined galaxy. Now, researchers say they have found compelling evidence of such a pairing. A distant galaxy seems to be firing off two beams of radiation from its center at different angles—a sign that a pair of supermassive black holes lurks at its heart. The two behemoths—each with a mass as large as 1 billion Suns—seem to orbit each other every 121 days. ...In as little as 100 years...the black holes should collide, shaking spacetime itself in a titanic burst of gravitational waves. That final burst “would be a really fantastic gravitational wave signal,” says team leader Silke Britzen of the Max Planc...

By Daniel Clery , Science.  Excerpt: It’s as if the baby universe had caught a case of measles. Since NASA’s JWST observatory began peering into the distant universe in 2022, it has discovered a rash of “little red dots”—hundreds of them, shining within the first billion years of the 13.8-billion-year-old universe, so small and red that they defied conventional explanation. Only in the past few months has a picture begun to emerge. The little red dots, astronomers say, may be an entirely new type of object: a colossal ball of bright, hot gas, larger than the Solar System, powered not by nuclear fusion, but by a black hole. ...JWST couldn’t resolve the dots into a recognizable shape, which meant they must have been tiny—less than 2% of the diameter of the Milky Way....  Full article at https://www.science.org/content/article/early-universe-s-little-red-dots-may-be-black-hole-stars . 

By Daniel Clery , Science.  Excerpt: Astronomers studying the murky center of our Milky Way Galaxy have discovered something they never expected:  a pair of young stars orbiting each other near the supermassive black hole that is our Galaxy’s dark heart . The observation—reported today in Nature Communications—comes as a surprise because astrophysicists had thought the black hole’s intense gravity would either rip the stars in such a pair apart or squash them together. But the new object, dubbed D9, shows that such a “binary” can survive, at least briefly, near the black hole, and it could help explain other mysterious objects in the vicinity. ...For many years, two teams, in California and Germany, monitored the  closest of those stars . About 20 years ago, both proved the star’s eccentric, high-speed orbit could only arise if it was circling a compact object with extreme mass—a black hole. For that work, the teams’ leaders, Reinhard Genzel of the Max Planck Institu...

https://www.science.org/content/article/black-hole-center-milky-way-may-be-blasting-out-jet   By DANIEL CLERY , Science.  Excerpt: The supermassive black holes at the centers of many galaxies generate powerful jets, blasting particles thousands of light-years into space. This new image of the Milky Way’s black hole, known as Sagittarius A* (Sgr A*), suggests it may have one, too, but perhaps of a more modest nature. The image—taken with polarized light—was  released today by the Event Horizon Telescope (EHT) , a worldwide array of radio telescopes that in 2019 produced the  first ever image of a black hole . The new image shows light that is oriented in a particular direction, revealing magnetic field lines around the black hole. Although jets would not be visible in such a zoomed-in image, strong magnetic fields are thought to be essential in launching them.... See also European Southern Observatory press release . 

https://www.science.org/content/article/long-sought-hum-of-gravitational-waves-from-giant-black-holes-heard-for-first-time By Adam Mann, Science.  Excerpt: By turning networks of dead stars into galaxy-size gravitational wave detectors, radio astronomers have tuned into the slowly undulating swells in spacetime thought to arise from pairs of supermassive black holes (SMBHs) that are about to collide. In a simultaneous announcement today, five separate international teams said that after nearly 20 years of effort they had found evidence for these gravitational waves. They are far longer than the waves  first captured  by ground-based detectors in 2015, which emanate from collisions of star-size objects. The findings not only open up a new window in gravitational wave astronomy, but will also help researchers answer questions about the origin and evolution of SMBHs, objects that sit at the center of galaxies and weigh as much as billions of Suns.... 

https://news.berkeley.edu/2022/06/10/astronomers-may-have-detected-a-dark-free-floating-black-hole/ By Robert Sanders , UC Berkeley News.  Excerpt: If, as astronomers believe, the death of large stars leave behind black holes, there should be hundreds of millions of them scattered throughout the Milky Way galaxy. The problem is, isolated black holes are invisible. Now, a team led by University of California, Berkeley, astronomers has for the first time discovered what may be a free-floating black hole by observing the brightening of a more distant star as its light was distorted by the object’s strong gravitational field — so-called gravitational microlensing. The team, led by graduate student Casey Lam and  Jessica Lu , a UC Berkeley associate professor of astronomy, estimates that the mass of the invisible compact object is between 1.6 and 4.4 times that of the sun. Because astronomers think that the leftover remnant of a dead star must be heavier than 2.2 solar masses in or...

https://www.washingtonpost.com/science/2022/05/11/black-hole-milky-way By Daniel Clery, Science Magazine.   Excerpt: After 5 years, astronomers release picture of Sagittarius A*’s event horizon, ringed by bright gas. Astronomers today released the first image of the supermassive black hole at the center of the Milky Way Galaxy—or at least a picture of its shadow. Eight radio observatories around the globe and more than 300 scientists joined forces to image the object known as Sagittarius A* (Sgr A*), a feat thought impossible until just a few years ago. ...The team, known as the Event Horizon Telescope (EHT), in 2019 produced the  first ever image of a black hole , at the center of the nearby giant galaxy M87. The M87 black hole is 1600 times more massive than Sgr A*. Yet the similarity of the two images—bright rings of gas trapped in death spirals around these ultimate sinkholes—shows how Albert Einstein’s theory of gravity, general relativity, works the same at all scal...

https://www.sciencemag.org/news/2020/10/universe-teems-weird-black-holes-gravitational-wave-hunters-find Source:    By   Adrian Cho , Science Magazine.  Excerpt: Less than 5 years ago, physicists rocked the scientific world when they   first spotted gravitational waves —fleeting ripples in space and time—set off when two gargantuan black holes billions of light-years away swirled into each other. Since then, scientists have detected a scad of similar events,   mostly reported event by event . Today, however, researchers with a global network of gravitational wave detectors announced the first major statistical analyses of their data so far, 50 events in all. Posted online in four papers, the analyses show that black holes—ghostly ultraintense gravitational fields left behind when massive stars collapse—are both more common and stranger than expected. They also shed light on mysteries such as how such black holes pair up before merging....  

https://www.smithsonianmag.com/science-nature/closest-black-hole-180974815 / Source:   By Megan Gannon, Smithsonian Magazine. Excerpt: The pair of stars in a system called HR 6819 is so close to us that on a clear night in the Southern Hemisphere, a person might be able to spot them without a telescope. What that stargazer wouldn’t see, though, is the black hole hiding right there in the constellation Telescopium. At just 1,000 light-years away, it is the closest black hole to Earth ever discovered, and it could help scientists find the rest of the Milky Way's missing black holes. Dietrich Baade, an emeritus astronomer at the European Southern Observatory (ESO) in Germany and co-author of the study in Astronomy & Astrophysics, says the team never set out to find a black hole. They thought the HR 6819 system was a simple binary, made up of two visible stars orbiting each other. But their observations with the MPG/ESO 2.2-meter telescope at ESO’s La Silla Observatory in Chile...

https://www.nytimes.com/2020/03/06/science/black-hole-cosmos-astrophysics.html Source:   By Dennis Overbye, The New York Times. Excerpt: If there were ever sentient beings in the Ophiuchus cluster, a faraway conglomeration of galaxies in the southern sky, they are long gone. A few hundred million years ago, a mighty cosmic storm swept through that region of space. Hot gas suffuses the cluster, but the storm blew a crater through it more than a million light-years wide, leaving just a near-vacuum, a nattering haze of ultrahot electrical particles. The culprit, astronomers suspect, was a gigantic outburst of energy from a supermassive black hole — the biggest explosion ever documented in the universe, according to Simona Giacintucci, a radio astronomer at the Naval Research Laboratory and the leader of the research team....

https://www.sciencenews.org/article/black-hole-first-picture-event-horizon-telescope Source:   By Lisa Grossman and Emily Conover, ScienceNews. Excerpt: A world-spanning network of telescopes called the Event Horizon Telescope [EHT; https://eventhorizontelescope.org/ ] zoomed in on the supermassive monster in the galaxy M87 to create this first-ever picture of a black hole.  ...“We’ve been studying black holes so long, sometimes it’s easy to forget that none of us have actually seen one,” France Córdova, director of the National Science Foundation....  ...The image also provides a new measurement of the black hole’s size and heft. ...Estimates made using different techniques have ranged between 3.5 billion and 7.22 billion times the mass of the sun. But the new EHT measurements show that its mass is about 6.5 billion solar masses. ...The team has also determined the behemoth’s size — its diameter stretches 38 billion kilometers — and that the black hole spins clockwis...