Kategorie: Science Articles

Astronomers have taken a crucial step in showing that the most massive black holes in the universe can create their own meals. Data from NASA’s Chandra X-ray Observatory and the Very Large Telescope (VLT) provide new evidence that outbursts from black holes can help cool down gas to feed themselves.
This study was based on observations of seven clusters of galaxies. The centers of galaxy clusters contain the universe’s most massive galaxies, which harbor huge black holes with masses ranging from millions to tens of billions of times that of the Sun. Jets from these black holes are driven by the black holes feasting on gas.
These images show two of the galaxy clusters in the study, the Perseus Cluster and the Centaurus Cluster. Chandra data represented in blue reveals X-rays from filaments of hot gas, and data from the VLT, an optical telescope in Chile, shows cooler filaments in red.
The results support a model where outbursts from the black holes trigger hot gas to cool and form narrow filaments of warm gas. Turbulence in the gas also plays an important role in this triggering process.
According to this model, some of the warm gas in these filaments should then flow into the centers of the galaxies to feed the black holes, causing an outburst. The outburst causes more gas to cool and feed the black holes, leading to further outbursts.
This model predicts there will be a relationship between the brightness of filaments of hot and warm gas in the centers of galaxy clusters. More specifically, in regions where the hot gas is brighter, the warm gas should also be brighter. The team of astronomers has, for the first time, discovered such a relationship, giving critical support for the model.
This result also provides new understanding of these gas-filled filaments, which are important not just for feeding black holes but also for causing new stars to form. This advance was made possible by an innovative technique that isolates the hot filaments in the Chandra X-ray data from other structures, including large cavities in the hot gas created by the black hole’s jets.
The newly found relationship for these filaments shows remarkable similarity to the one found in the tails of jellyfish galaxies, which have had gas stripped away from them as they travel through surrounding gas, forming long tails. This similarity reveals an unexpected cosmic connection between the two objects and implies a similar process is occurring in these objects.
This work was led by Valeria Olivares from the University of Santiago de Chile, and was published Monday in Nature Astronomy. The study brought together international experts in optical and X-ray observations and simulations from the United States, Chile, Australia, Canada, and Italy. The work relied on the capabilities of the MUSE (Multi Unit Spectroscopic Explorer) instrument on the VLT, which generates 3D views of the universe.
NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
Read more from NASA’s Chandra X-ray Observatory.
Learn more about the Chandra X-ray Observatory and its mission here:
https://www.nasa.gov/chandra
https://chandra.si.edu
Visual Description
This release features composite images shown side-by-side of two different galaxy clusters, each with a central black hole surrounded by patches and filaments of gas. The galaxy clusters, known as Perseus and Centaurus, are two of seven galaxy clusters observed as part of an international study led by the University of Santiago de Chile.
In each image, a patch of purple with neon pink veins floats in the blackness of space, surrounded by flecks of light. At the center of each patch is a glowing, bright white dot. The bright white dots are black holes. The purple patches represent hot X-ray gas, and the neon pink veins represent filaments of warm gas. According to the model published in the study, jets from the black holes impact the hot X-ray gas. This gas cools into warm filaments, with some warm gas flowing back into the black hole. The return flow of warm gas causes jets to again cool the hot gas, triggering the cycle once again.
While the images of the two galaxy clusters are broadly similar, there are significant visual differences. In the image of the Perseus Cluster on the left, the surrounding flecks of light are larger and brighter, making the individual galaxies they represent easier to discern. Here, the purple gas has a blue tint, and the hot pink filaments appear solid, as if rendered with quivering strokes of a paintbrush. In the image of the Centaurus Cluster on the right, the purple gas appears softer, with a more diffuse quality. The filaments are rendered in more detail, with feathery edges, and gradation in color ranging from pale pink to neon red.

Source: https://www.nasa.gov/image-article/black-holes-can-cook-for-themselves-chandra-study-shows/

Published in 1962 by American astronomer Frank Drake, Ph.D., the eponymous Drake equation sought to estimate the number of detectable alien civilizations in the Milky Way galaxy. This equation takes into account the average rate of star formation in the galaxy, the fraction of those stars that have orbiting planets, and the average number of those planets per star that can support life. It gets hairier: This formula also considers what fraction of those planets could support intelligent organisms, and whether those organisms can develop technology capable of contacting others.
Now, researchers in Switzerland and the U.K. have homed in on one particular aspect of this equation to contemplate how a crucial component of our universe affects star formation and, by extension, the possibility of intelligent life. Their paper studies the relationship between the density of a mysterious force in the universe, called dark energy, and the overall number of stars formed in the universe’s history. Published in November 2024 in the journal Monthly Notices of the Royal Astronomical Society, this work describes a new theoretical model of cosmic star formation applied to our universe as well as other possible ones with varying dark energy densities.
In other words, it ponders the likelihood of intelligent life existing in the multiverse.
To approach this question, the team tackled anthropic reasoning. This line of thinking is the idea that we can derive fundamental properties of the universe based on the fact that we exist. There’s so much we don’t know about the universe, but one thing we know for certain is that, at least in one tiny corner, it allows humans to exist. That starting point guides the way for understanding other characteristics of the universe.
Anthropic reasoning can offer explanations for the amount of dark energy in our universe. In the late 1980s, physics Nobel laureate Steven Weinberg used this idea to propose that the observed density of dark energy in the universe informs the existence of intelligent life within it. He contemplated that larger densities of dark energy would cause the universe to expand faster, negating gravity’s effort to clump matter together into galaxies, which would discourage star formation, and therefore, life.
Dark energy is an enigmatic force that may be causing the universe to expand at an accelerated rate. While it doesn’t explicitly factor into the Drake equation, dark energy does relate to star formation, which is key to the formula. In the same way that life on Earth wouldn’t exist without our sun, stars are a prerequisite for the formation of intelligent life. So, contemplating how varying amounts of dark energy in the universe impact star formation could tell us about other possible universes, too.
“Since stars are a precondition for the emergence of life as we know it, we then ask whether it would be easier for intelligent life to spawn in our Universe, or in a hypothetical universe with a different dark energy content,” the paper’s first author Daniele Sorini, Ph.D, a postdoctoral research associate in cosmology and astrophysics at Durham University’s Institute for Computational Cosmology in the U.K., says in an email to Popular Mechanics.
Dark energy is baffling. According to Sorini, “while we can measure the density of dark energy, we do not really know what it is.” Still, measuring it is useful. For example, in the paper, Sorini and his team plot the efficiency of star formation throughout the cosmos in relation to varying amounts of dark energy density. The team found that the amount of stars formed in the universe’s history is maximized if dark energy density is about one-tenth its observed value. That means, hypothetically, the ideal universe for forming life—because the formation of life comes from the formation of stars—would have less dark energy than our universe. Assuming that this amount is proportional to stars formed, this would make for the ideal universe to create intelligent life. In this optimal scenario, 27 percent of ordinary matter in the universe converts to stars, while in our universe, it’s only 23 percent. This gap demonstrates that while our universe is close to hosting the optimal conditions for life, it’s still not the most ideal.
Cosmic star formation continues to decrease with higher dark energy densities. Hypothetically, a universe with increasing dark energy density is less hospitable to the formation of intelligent life. Likewise, Weinberg posited that very few universes with intelligent life in the multiverse would have limited dark energy density.
As Weinberg had done, Sorini and his co-authors pondered what might change if a universe contained a different density of dark energy. But, considering a multiverse wherein each universe contains a different dark energy density—observed by one intelligent observer—the team found that 99.5 percent of these universes boasted a higher dark energy density than our own universe’s.
“This might seem at odds with the fact that higher dark energy abundance leads to lower likelihood of generating intelligent life,” Sorini says. “But there is no contradiction.” He explains that, individually, universes with higher dark energy densities contain fewer intelligent observers, though there are many more such universes. The paper’s calculations show that, taken collectively, these multiverses contain intelligent observers.
However, Sorini emphasizes that this paper doesn’t aim to prove the existence of the multiverse or locate extraterrestrial life. Rather, it’s a novel way of considering how dark energy density in the universe could impact star formation, which serves as a proxy for the development of intelligent life.
“Whether the multiverse scenario is real or not is beside the point of our paper,” Sorini says. “It is a thought experiment to understand whether we can provide a suitable explanation of the puzzling observed value of the dark energy density in our universe, based on the fact that we exist.”

source: https://www.popularmechanics.com/science/a63635014/aliens-parallel-universe/

Japan’s government has been considering joining a U.S.-led space telescope initiative to search for Earth-like planets and extraterrestrial life, aiming to contribute technology and secure key research opportunities.
The NASA-led „Habitable Worlds Observatory“ project plans to launch a large-scale space telescope in the early 2040s, designed to observe wavelengths like ultraviolet and X-rays that cannot penetrate the Earth’s atmosphere.
Tokyo plans to have a specialized team within the Japan Aerospace Exploration Agency assess what potential technological contributions can be made.
Government officials view the space telescope endeavor as a significant international project, comparable to the Artemis lunar exploration program, which has over 50 countries involved. Joining the initiative would bolster Japan’s role in global space science and provide priority access to observation opportunities.

A render of a design for the Habitable Worlds Observatory. (Photo courtesy of NASA’s Goddard Space Flight Center Conceptual Image Lab)(Kyodo
Serving as the successor to the James Webb Space Telescope, launched in 2021, the envisioned telescope will orbit 1.5 million kilometers from Earth. It will utilize infrared, visible and UV light to detect exoplanets with conditions such as liquid water and atmospheres capable of supporting life.
Detecting Earth-like planets involves capturing faint light signals obscured by the brightness of stars. Drawing on expertise gained from developing instruments for the Subaru Telescope in Hawaii, Japan hopes to contribute observation equipment and remote maintenance technologies to the project.
Although Japan did not take part in the development of the James Webb Space Telescope, which has made major discoveries including uncovering the structure of the early universe, experts highlight the importance of contributing to future large-scale space initiatives.
„Discovering life beyond Earth would deepen our understanding of what life is and how it developed on our planet,“ said Satoshi Miyazaki, director of the National Astronomical Observatory of Japan’s Hawaii Observatory.
He added that Japan must leverage its unique technologies to maintain a leading role in global space exploration efforts.

Since the first modern SETI (Search for ExtraTerrestrial Intelligence) studies tried to detect alien transmissions in the early 1960s, scientists on Earth have been on the alert for strange cosmic signals with no reasonable explanation. So far, they haven’t positively identified any signals as evidence of intelligent alien life among the stars, but the search continues.
Most SETI telescope searches aim to observe a vast expanse of sky or zero in on a specific star system or group of stars. They usually try to intercept signals that potential aliens could have aimed at Earth or those that pass close by. But what if aliens are transmitting messages from one exoplanet to another instead? If they exist, we may now have a way to eavesdrop on alien conversations, leveling up humanity’s search for intelligent life far from Earth.
Working with his team at Penn State University, astronomer Nick Tusay, a graduate student working on his Ph.D., came up with a new technique that tests indicate would detect alien radio chatter. From our Earthly point of view, we can observe when one exoplanet—a planet that is not part of our solar system—passes in front of and blocks another. This is called occultation. However, the occulting planet does not always completely cover the planet behind it. So, any message a hypothetical alien transmits from the occulted planet can spill over into space, and our radio telescopes could detect it.
“I want to be able to find or at least look for the kind of signals that we put out all the time, from an alien civilization going about its business doing its thing, not intending to signal anyone,” says Tusay, who led a study published in July 2024 in The Astronomical Journal.
Tusay’s method of listening in on alien conversations during planet-planet occultations (PPOs) is designed to seek out narrowband radio signals. While there are many different types of radio waves that are emitted by objects such as quasars or pulsars, narrowband signals are glaringly artificial and are the type used by transmitters. We only know of one species that has been able to produce these signals, and that’s us. Humans send these signals into space when communicating with spacecraft via NASA’s Deep Space Network. The fact that these signals cannot occur naturally is an advantage for SETI, because if radio telescopes on Earth were to detect one coming from space, it would mean that it is definitely artificial.
Seth Shostak, Ph.D., Senior Astronomer at the SETI Institute and renowned SETI expert, agrees that narrowband signals would be a sure sign that someone out there is communicating, though not necessarily with us. There is always the possibility that extraterrestrials might be using a type of signal we cannot even fathom yet. However, Shostak, who is also an astrophysicist, believes it is likely aliens would use the same methods of communications that humans do.
“Maybe ether aliens have a different signaling system to what we can imagine, but the physics on their world are the same as the physics here,” he says. “Sending radio signals is something that they would probably do too, because it’s congruent with the physics the universe has.”
The more practical reason for relying on narrowband signals transmitted between planets is that we understand them, according to SETI historian Rebecca Charbonneau, Ph.D., author of Mixed Signals: Alien Communication Across the Iron Curtain. During the advent of SETI in the late 1950s and early 1960s, when the Space Race was taking off, humans were sending artificial signals into space. And they were already starting to wonder if there were intelligent beings out there who were doing the same.
“We’re highly influenced by our environment when it comes to thinking of what we might expect to see in other words, because radio is the primary mechanism with which humans have historically communicated,” says Charbonneau.
As our technology has evolved, we have shifted from radio to other modes of communication, such as fiber optics, internet, and cables buried deep beneath the ocean. This shift also means that radio signals from our telescopes may take a backseat to these newer types of signals. If intelligent aliens are looking for other life in the universe, then they may or may not be able to detect our variety of signals.
However, it’s possible that none of these signals may resonate with an advanced civilization, which could be millions—or possibly billions of years—older than ours; its members could be communicating in ways only science fiction could fathom. As a recent study published in The Open Journal of Astrophysics explores, it is possible that alien communications technologies are so advanced, they may be talking to each other using gravitational waves. These are ripples in spacetime, and physicists don’t yet fully understand them.
The problem is that—unlike narrowband radio waves—our science cannot distinguish between gravitational waves that are natural and those that may be artificial. That lack of knowledge still does not discourage Tusay. While he will not be developing the eavesdropping technique further, he plans to leave it in the literature as a proof of concept, so that future scientific progress may make the adjustments needed to pick up unnatural signals. Whether we could actually decode any type of signal from another civilization is an entirely different question, though.

Source: https://www.popularmechanics.com/space/a63022036/alien-radio-signals/