Latest news with #observatories
Yahoo
3 days ago
- Science
- Yahoo
Scientists Detect Sign of Something Impossible Out in Deep Space
The very concept of black holes seems improbable. Albert Einstein infamously refused to believe they could exist, even though his theory of general relativity was instrumental in predicting them. Now, scientists have witnessed evidence of something about these baffling cosmic monstrosities that further stretches the boundaries of both physics and credulity: a titanic collision of two already enormous black holes so utterly extreme that it has scientists wondering if the event they seem to have detected is even possible. As detailed in a new yet-to-be-peer-reviewed paper by a consortium of physicists, the resulting black hole, whose signal has been designated GW231123, boasts an astonishing mass about 225 times that of our Sun — easily making it the largest black hole merger ever detected. Previously, the record was held by a merger that formed a black hole of about 140 solar masses. "Black holes this massive are forbidden through standard stellar evolution models," Mark Hannam at the Laser Interferometer Gravitational-Wave Observatory (LIGO), which made the detection, said in a statement about the work. "This is the most massive black hole binary we've observed through gravitational waves, and it presents a real challenge to our understanding of black hole formation." Black holes can produce huge, propagating ripples in spacetime called gravitational waves, which were predicted by Einstein back in 1916. Nearly 100 years later, LIGO — which consists of two observatories on opposite corners of the US — made history by making the first ever detection of these cosmic shudders. The merger was first spotted in November 2023 in a gravitational wave, GW231123, that lasted just a fraction of a second. Even so, it was enough to infer the properties of the original black holes. One had a mass roughly 137 times the mass of the Sun, and the other was around 103 solar masses. During the lead up to the merger, the pair circled around each other like fighters in a ring, before finally colliding to form one. These black holes are physically problematic because it's likely that one, if not both of them, fall into an "upper mass gap" of stellar evolution. At such a size, it's predicted that the stars that formed them should have perished in an especially vicious type of explosion called a pair-instability supernova, which results in the star being completely blown apart, leaving behind no remnant — not even a black hole. Some astronomers argue that the "mass gap" is really a gap in our observations and not the cause of curious physics. Nonetheless, the idea is "a hill at least some people were willing to get wounded on, if not necessarily die on," Cole Miller of the University of Maryland, who was not involved in the research, told ScienceNews. But perhaps the black holes weren't born from a single star. "One possibility is that the two black holes in this binary formed through earlier mergers of smaller black holes," Hannam said in the statement. Equally extreme as their weight classes are their ludicrously fast spins, with the larger spinning at 90 percent of its maximum possible speed and the other at 80 percent, both of which are equal to very significant fractions of the speed of light. In earthly terms, it's somewhere around 400,000 times our planet's rotation speed, according to the scientists. "The black holes appear to be spinning very rapidly — near the limit allowed by Einstein's theory of general relativity," Charlie Hoy, a member of the LIGO Scientific Collaboration at the University of Portsmouth, said in the statement. "That makes the signal difficult to model and interpret. It's an excellent case study for pushing forward the development of our theoretical tools." The researchers will present their findings at the GR-Amaldi meeting in Glasgow, which takes place this week. "It will take years for the community to fully unravel this intricate signal pattern and all its implications," according to LIGO member Gregorio Carullo at the University of Birmingham — so, tantalizingly, we're likely only scratching the surface of this mystery. More on space: James Webb Space Telescope Spots Stellar Death Shrouds
Yahoo
18-06-2025
- Science
- Yahoo
Starlink Satellites Are 'Leaking' Radio Emissions
Specialists at Australia's Square Kilometer Array (SKA) released a report this week showing Starlink's unexpected impact on radio astronomy. Despite national and international protections against radio emissions in certain bands, Starlink is clogging the skies with electromagnetic pollution. Light pollution stretches far beyond the hazy glow of a city on the horizon. Down in the radio portion of the electromagnetic spectrum, governments barter sections of light. Large portions of bandwidth stay reserved for the military, while others get auctioned off (sometimes literally) to communications companies. Squeezed in between these chunks of spectrum lie bands for public broadcasting, HAM radio, and science. Governments, corporations, and private citizens are supposed to stay away from protected bands so that radio telescopes can observe in peace. When the Starlink satellites launched, SpaceX collaborated with key radio astronomy observatories to avoid broadcasting while transiting above telescopes. Strategies include turning off Starlink WiFi services completely in certain regions of the sky. The resulting disruptions to Starlink operations are not insignificant. Spectrum management, especially in the United States, involves give-and-take on both sides. But American observatories have the benefit of observing at mid- to high-frequencies, at least by radio standards. Those frequency bands are less polluted than low frequencies, because emitting at low frequencies takes less energy and so costs less. If corporations and the military ignored protected bands, it would cause serious problems for radio astronomy. But a new study by engineers at the SKA suggests unintended electromagnetic radiation, or UEMR, may be a bigger issue than intended radiation. The SKA is still under construction. When completed, it will be the most powerful radio telescope in the world. The low-frequency part of the telescope (SKA-Low) is designed to go after trace echoes from when matter began to coalesce 13 billion years ago. SKA-Low looks odd even by the standards of radio telescopes. A thick forest of metallic Christmas trees in the Australian desert maximizes sensitivity to faint signals. But the new era of radio telescopes is butting up against a new era of satellites. There are more satellites in orbit than ever before, including massive networks of related satellites called constellations. With 7,000 satellites in Low Earth Orbit, Starlink is the biggest constellation. As they transit above SKA-Low, Starlink satellites release radio emissions through multiple protected bands. In a pre-print of their study, the SKA-Low team reports 112,534 intrusions of Starlink satellites in their radio images. Their month-long study showed that 30% of all Starlink satellites in the sky at the time appear in their data. Most of this emission seems to be accidental. UEMR from Starlink interfering with radio astronomy isn't unprecedented. During the initial launch phase, radio astronomers found that the propulsion system on the satellites emitted at unexpectedly low frequencies, decreasing the quality of astronomical data in an already polluted band. But the satellites had all been launched at the time of this new study. So where is all this radio pollution coming from? We don't know the various origins of the UEMR the SKA-Low team observed, except for one feature at 99.7 MHz. If that sounds like an FM radio band, it's no coincidence. Starlink satellites bounce FM radio shows back down to the Earth. For telescopes carefully located in radio-quiet zones, that's not ideal. Fixing this issue is particularly crucial to the success of SKA-Low, which seeks to look further back in time than any telescopes in a similar radio band. Signals from the early universe are very faint, and Starlink satellites are not. Unfortunately, the codes governing spectrum use only ban intended radio emission in protected bands. Consider a hyperbolic analogy: Imagine if murder were illegal, but manslaughter wasn't. Spectrum experts and regulators are currently discussing how to address this issue. For now, though, as long as Starlink is here, so are the unintended radio emissions.
