Latest news with #PaulaSánchezSáez
Time of India
27-05-2025
- Science
- Time of India
Astronomers stunned as sleeping Black Hole roars back to life after 20 years
The night sky was once thought of as a calm, unchanging dome, but over the years, it has become a dynamic canvas for discovery. Modern telescopes like the Zwicky Transient Facility (ZTF) are now looking deep into the night sky and the cosmos in real time, capturing sudden flashes, flares, and transformations as they happen. The advancement in technology every day is giving ways to observe the universe and witness cosmic events that happen over days, weeks, or even years, events that were previously considered too rare or distant to catch in action. One such surprise came up during late 2019, when a quiet galaxy, SDSS1335+0728, suddenly lit up in the Virgo constellation, located about 300 million light-years from Earth. What followed has kept astronomers captivated for over four years, and the show isn't over yet. What is happening in the cosmos? In December 2019, astronomers spotted that the quiet core of SDSS1335+0728, a spiral galaxy in the Virgo constellation, suddenly brightened by several orders of magnitude. Located about 300 million light-years away, this galaxy had shown no signs of activity for over two decades. Now, its center home to a supermassive black hole roughly a million times the mass of the Sun was blazing to life. Astronomers immediately suspected either a tidal disruption event, where a star gets torn apart by a black hole's gravity, or the first signs of an active galactic nucleus (AGN) waking up. But what made this case unusual was the duration. More than four years later, the flare hasn't faded, far exceeding the timescale of typical star-eating episodes or supernovae. 'This behavior is unprecedented,' said Paula Sánchez Sáez, lead author of the study published in Astronomy & Astrophysics and an astronomer at the European Southern Observatory (ESO) in Germany. Instruments including ESO's X-shooter spectrograph detected a consistent rise in ultraviolet, optical, and infrared light—and in February 2024, X-ray emissions began for the first time. The spectrum now reveals broad emission lines, meaning gas moving near light-speed close to the black hole. 'Suddenly, its core starts showing dramatic changes in brightness, unlike any typical event we've seen before,' Sánchez Sáez added. Co-author Lorena Hernández García of the Millennium Institute of Astrophysics (MAS) in Chile noted, 'If so, this would be the first time that we see the activation of a massive black hole in real time.' There is a new nuclear activity in space That makes SDSS1335+0728 a cosmic rarity. It doesn't shine as brightly as classic quasars, but its persistence rules out most common flare types. It sits in a gray area, possibly marking a new category of nuclear activity. 'This could also happen to our own Sgr A*, the massive black hole at the center of our galaxy,' said Claudio Ricci of Diego Portales University in Chile. 'But it's unclear how likely that is.' Researchers are now trying to determine whether this is a very slow tidal disruption, the birth of a new accretion disk, or something never seen before. Each scenario could reshape models of how supermassive black holes evolve today. 'We expect that instruments such as MUSE on the VLT and those on the upcoming Extremely Large Telescope will be key to understanding why the galaxy is brightening,' said Sánchez Sáez.
Yahoo
11-04-2025
- Science
- Yahoo
For the first time, astronomers watch a black hole ‘wake up' in real-time
A black hole is a terrifying concept, but the mysterious nexus of physics and space-time isn't always gobbling up matter. While famous for devouring anything and everything in its gravitational pull, black holes aren't constantly destructive. In fact, they often exhibit long periods of dormancy. Astronomers had never witnessed a black hole 'wake up' in real time—until now. Researchers have spent the past few years watching a black hole re-awaken roughly 300 million light-years away from Earth. And what they've documented challenges prevailing theories about black hole lifecycles. The groundbreaking observations are detailed in a study published on April 11 in Nature Astronomy. For decades, the supermassive black hole anchoring a galaxy known as SDSS1335+0728 in the Virgo constellation hasn't displayed much activity. But beginning in late 2019, astronomers noticed it began to emit intermittent, bright flashes of energy. They soon reclassified the galaxy's center as an active galactic nucleus nicknamed 'Ansky,' and enlisted telescopes from NASA and the ESA to help study the unexpected event. 'When we first saw Ansky light up in optical images, we triggered follow-up observations using NASA's Swift X-ray space telescope, and we checked archived data from the eROSITA X-ray telescope, but at the time we didn't see any evidence of X-ray emissions,' Paula Sánchez Sáez, a researcher at the European Southern Observatory in Germany and lead researcher of the first team to study Ansky, said in a statement. Fast forward to February 2024 when Lorena Hernández-García at Chile's Valparaiso University began detecting even more regular X-ray bursts from Ansky. The rare events allowed astronomers to once again aim their tools like the XMM-Newton X-ray space telescope and NASA's Chandra, NICER, and Swift telescopes at Ansky. Hernández-García and collaborators then determined the black hole was displaying a phenomenon known as a quasiperiodic eruption, or QPE. 'QPEs are short-lived flaring events. And this is the first time we have observed such an event in a black hole that seems to be waking up,' said Hernández-García. XMM-Newton proved particularly critical to studying Ansky's behavior, since it is the only telescope sensitive enough to capture fainter background X-ray light amid the black hole's stronger X-ray bursts. By comparing the two phases, astronomers could calculate the amount of energy released by Ansky during its more active periods. While a black hole inevitably destroys everything it captures, objects behave differently during their impending demise. A star, for example, generally stretches apart into a bright, hot, fast-spinning disc known as an accretion disc. Most astronomers have theorized that black holes generate QPEs when a comparatively small object like a star or even a smaller black hole collides with an accretion disc. In the case of Ansky, however, there isn't any evidence linking it to the death of a star. 'The bursts of X-rays from Ansky are ten times longer and ten times more luminous than what we see from a typical QPE,' said MIT PhD student and study co-author Joheen Chakraborty. 'Each of these eruptions is releasing a hundred times more energy than we have seen elsewhere. Ansky's eruptions also show the longest cadence ever observed, of about 4.5 days.' Astronomers must now consider other explanations for Ansky's remarkable behavior. One theory posits that the accretion disc could come from nearby galactic gas pulled in by the black hole instead of a star. If true, then the X-rays may originate from high energy shocks to the disc caused by a small cosmic object repeatedly passing through and disrupting orbital matter. As it stands, astronomers possess more QPE models than data from actual events. Thanks to Ansky's reawakening, that may soon change. 'We don't yet understand what causes them,' said Hernández-García. 'Studying Ansky will help us to better understand black holes and how they evolve.'
