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Brown dwarfs could be hiding dark matter inside their cores – if they are, there would be signs that could help us track it down

Brown dwarfs could be hiding dark matter inside their cores – if they are, there would be signs that could help us track it down

Even Earth’s mightiest telescopes aren’t up to the task of imaging Apollo lunar landing sites. A lack of resolution is the biggest reason why

Personal stories and research reveal the challenges of family caregiving.

Here's what to expect from this aurora season and how to best prepare for your northern lights hunting experience.

As it’s name suggests, dark matter is dark! That means it’s largely invisible to us and only detectable through its interaction with gravity. One of the leading theories to explain the stuff that makes up the majority of the matter in the Universe are WIMPs, Weakly Interacting Massive Particles. They are just theories though and none have been detected. An exciting new experiment called LUX-ZEPLIN has just completed 280 days of collecting data but still, no WIMPs have been detected above 9 Gev/c2. There are plans though to narrow the search.

The concept of dark matter was first proposed by Fritz Zwicky in 1930’s who noticed that galaxies were moving too fast to be held together by ‘normal’ visible matter. His work was expanded upon by Vera Rubin in the 1970’s who confirmed that stars around the outer regions of galaxies were moving faster than expected. The conclusion of these observations is that there was some form of invisible matter making up about 85% of the mass of the Universe. New results from LUX-ZEPLIN are homing in on the WIMP model to describe the nature of dark matter. 

Fritz Zwicky. Image Source: Fritz Zwicky Stiftung website

LUX-ZEPLIN is an instrument designed to detect dark matter. Located 1.6km underground at the Sanford Underground Research Facility in South Dakota, it’s a massive tank filled with 10 tons of liquid xenon waiting and watching for tiny interactions between dark matter and normal particles. It is shielded from cosmic radiation and other background noise by an onion layer design with each layer blocking out radiation or tracking particle interactions to rule out erroneous dark matter interactions. The principle is simple, a passing WIMP could knock into a xenon nucleus causing it to move and emit light and electrons in the process. It is these signals the teams are looking for. Along with new analytical techniques the teams using it hope they will finally unlock the mysteries of dark matter. 

A view of the Large Underground Xenon (LUX) dark matter detector. Shown are photomultiplier tubes that can ferret out single photons of light. Signals from these photons told physicists that they had not yet found Weakly Interacting Massive Particles (WIMPs) Credit: Matthew Kapust / South Dakota Science and Technology Authority

Following 280 days worth of data, no dark matter WIMPs were detected. Focussing their attention on WIMPs with a mass above 9 Gev/c2 the team found nothing despite the sensitivity of the detector. Having explored 9 Gev/c2 the team plans to start probing different energy levels as the hunt continues. The results had been announced at two physics conferences on 26 August TeV Particle Astrophysics 2024 in Chicago and LIDINE 2024 in São Paulo. 

The team applied an interesting new technique called ‘salting’ which adds fake WIMP signals during the collection of the data. The approach hides real data until the very end when an ‘unsalting’ technique removes them. This avoids unconscious bias and stops researchers from overly interpreting the data. 

Over the few years and by 2028, the team plan to collect at least 1,000 days of data which will be analysed using the new techniques. They will be using the data to study other rare phenomenon like the decay of xenon atoms, neutrino-less double beta decay and born-8 neutrinos from the Sun. There is still much work to do but the 250 scientists at LUX-ZEPLIN are hopeful. LUX-ZEPLIN’s physics coordinator Scott Kravitz from the University of Texas summed it up beautifully ‘Our ability to search for dark matter is improving at a rate faster than Moore’s Law. If you look at an exponential curve, everything before now is nothing. Just wait until you see what comes next.’

Source : Experiment sets new record in search for dark matter

The post New Limits on Dark Matter appeared first on Universe Today.

In the opening to Octavia E. Butler's prescient science fiction novel Parable of the Sower, the latest pick for the New Scientist Book Club, we are introduced to Lauren Olamina and start to learn about the dystopian future her story takes place in

In the opening to Octavia E. Butler's prescient science fiction novel Parable of the Sower, the latest pick for the New Scientist Book Club, we are introduced to Lauren Olamina and start to learn about the dystopian future her story takes place in

The Hugo award-winning author explains how she finally got to grips with Octavia E. Butler's dystopian novel, the latest pick for the New Scientist Book Club, on a third read

The Hugo award-winning author explains how she finally got to grips with Octavia E. Butler's dystopian novel, the latest pick for the New Scientist Book Club, on a third read

Video: 00:02:32

Sentinel-2C is ready for launch! The new satellite will soon join its Copernicus Sentinel-2 family in orbit – where it will continue to provide detailed views of Earth’s land and coastal waters.

The mission is based on a constellation of two identical satellites: Sentinel-2A and Sentinel-2B. The constellation was originally designed to monitor land surfaces – but its scope has since expanded.

It now covers a wide range of applications including deforestation, water quality, monitoring natural disasters, methane emissions and much more.

Sentinel-2C, once in orbit, will replace the Sentinel-2A unit – prolonging the life of the Sentinel-2 mission – ensuring a continuous supply of data for Copernicus, the Earth observation component of the EU Space Programme.

Tune in to ESA WebTV on 4 September from 03:30 CEST to watch the satellite soar into space on the last Vega rocket to be launched from Europe’s Spaceport in Kourou, French Guiana. 

Access the related broadcast quality footage. 

Discover where space begins: the guide to ESA’s establishments

ESA's Prospect package, including drill and a miniaturised laboratory, will fly to the Moon’s South Polar region in search of volatiles, including water ice, as part of NASA’s Commercial Lunar Payload Services initiative.

When the James Webb Space Telescope provided astronomers with a glimpse of the earliest galaxies in the Universe, there was some understandable confusion. Given that these galaxies existed during “Cosmic Dawn,” less than one billion years after the Big Bang, they seemed “impossibly large” for their age. According to the most widely accepted cosmological model—the Lambda Cold Dark Matter (LCDM) model—the first galaxies in the Universe did not have enough time to become so massive and should have been more modestly sized.

This presented astronomers with another “crisis in cosmology,” suggesting that the predominant model about the origins and evolution of the Universe was wrong. However, according to a new study by an international team of astronomers, these galaxies are not so “impossibly large” after all, and what we saw may have been the result of an optical illusion. In short, the presence of black holes in some of these early galaxies made them appear much brighter and larger than they actually were. This is good news for astronomers and cosmologists who like the LCDM the way it is!

The study was led by Katherine Chworowsky, a graduate student at the University of Texas at Austin (UT) and a National Science Foundation (NSF) Fellow. She was joined by colleagues from UT’s Cosmic Frontier Center, NSF’s NOIRLab, the Dunlap Institute for Astronomy & Astrophysics, the Mitchell Institute for Fundamental Physics and Astronomy, the Cosmic Dawn Center (DAWN), the Niels Bohr Institute, the Netherlands Institute for Space Research (SRON), NASA’s Goddard Space Flight Center, the European Space Agency (ESA), the Space Telescope Science Institute (STScI), and other prestigious universities and institutes. The paper that details their findings recently appeared in The Astrophysical Journal.

The first image taken by the James Webb Space Telescope, featuring the galaxy cluster SMACS 0723. Credit: NASA, ESA, CSA, and STScI

The data was acquired as part of the Cosmic Evolution Early Release Science (CEERS) Survey, led by Steven Finkelstein, a professor of astronomy at UT and a study co-author. In a previous study, Avishai Dekel and his colleagues at the Racah Institute of Physics at the Hebrew University of Jerusalem (HUJI) argued that the prevalence of low-density dust clouds in the early Universe allowed for rapid star formation in galaxies. Dekel and Zhaozhou Li (a Marie Sklodowska-Curie Fellow at HUJI) were also co-authors of this latest study.

As Chworowsky and her colleagues explained, the observed galaxies only appeared massive because their central black holes were rapidly consuming gas. This process causes friction, causing the gas to emit heat and light, creating the illusion of there being many more stars and throwing off official mass estimates. These galaxies appeared as “little red dots” in the Webb image (shown below). When removed from the analysis, the remaining galaxies were consistgent with what the standard LCDM model predicts.

“So, the bottom line is there is no crisis in terms of the standard model of cosmology,” Finkelstein said in a UT News release. “Any time you have a theory that has stood the test of time for so long, you have to have overwhelming evidence to really throw it out. And that’s simply not the case.”

However, there is still the matter of the number of galaxies in the Webb data, which are twice as many as the standard model predicts. A possible explanation is that stars formed more rapidly in the early Universe. Essentially, stars are formed from clouds of dust and gas (nebulae) that cool and condense to the point where they undergo gravitational collapse, triggering nuclear fusion. As the star’s interior heats up, it generates outward pressure that counteracts gravity, preventing further collapse. The balance of these opposing forces makes star formation relatively slow in our region of the cosmos.

The galaxy cluster SMACS0723, with the five galaxies selected for closer study. Credit: NASA, ESA, CSA, STScI / Giménez-Arteaga et al. (2023), Peter Laursen (Cosmic Dawn Center).

According to some theories, the Universe was much denser than it is today, which prevented stars from blowing out gas during formation, thus making the process more rapid. These findings echo what Dekel and his colleagues argued in their previous paper, though it would account for there being more galaxies rather than several massive ones. Similarly, the CEERS team and other research groups have obtained spectra from these black holes that indicate the presence of fast-moving hydrogen gas, which could mean that they have accretion disks.

The swirling of these disks could provide some of the luminosity previously mistaken for stars. In any case, further observations of these “little red dots” are pending, which should help resolve any remaining questions about how massive these galaxies are and whether or not star formation was more rapid during the early Universe. So, while this study has shown that the LCDM model of cosmology is safe for now, its findings raise new questions about the formation process of stars and galaxies in the early Universe.

“And so, there is still that sense of intrigue,” said Chworowsky. “Not everything is fully understood. That’s what makes doing this kind of science fun, because it’d be a terribly boring field if one paper figured everything out, or there were no more questions to answer.”

Further Reading: UT News, The Astronomical Journal

The post Remember those Impossible Galaxies Found by JWST? It Turns Out They Were Possible After All appeared first on Universe Today.

The merging of black holes and neutron stars are among the most energetic events in the universe. Not only do they emit colossal amounts of energy, they can also be detected through gravitational waves. Observatories like LIGO/Virgo (Laser Interferometer Gravitational Wave Observatory) and KAGRA (The Kamioka Gravitational Wave Detector) have detected their gravitational waves but new gravitational wave observatories are now thought to be able to detect the collapse of a massive rapidly spinning star before it becomes a black hole. According to new research, collapsing stars within 50 million light years should be detectable. 

The acceleration of massive objects can create ripples in space-time known as gravitational waves. They were first predicted by Albert Einstein in 1915 in his General Theory of Relativity. The waves are thought to travel at the speed of light and carry energy across the cosmos. Unlike electromagnetic waves, the gravitational waves seem to interact weakly with matter which allows them to pass unimpeded through stars, planets and galaxies. In 2015, the first gravitational waves were detected by the LIGO.

LIGO Observatory

Black holes and neutron stars are the remains of the death of stars. When supermassive stars reach the end of their lives they create astronomically (pardon the pun) dense objects. Neutron stars are stellar cores where the space between neutrons has been squeezed out leaving behind one great big neutron, often just a few tens of kilometres across. The remains of even more massive stars get compressed to an object of infinitely small size, a singularity, the power house of a black hole. 

In a paper published in The Astrophysical Journal Letters by Ore Gottlieb and team, it proposes how the collapse and death of massive stars (of the region 15 to 20 times the mass of the Sun) can generate gravitational waves. As the star ends its life, the core runs out of fuel and no longer generates the thermonuclear force to stop the collapse. The collapse leaves behind a large disk that quickly spirals around before falling into the black hole and it is this that it is thought, generates gravitational waves. The team goes on to suggest that the various gravity wave detectors on Earth may well be able to detect them.

An artist’s illustration of a supermassive black hole (SMBH.) The SMBH in a distant galaxy expelled all the material in its accretion disk, clearing out a vast area. Image Credit: ESA

To date, only merger events have been observed through gravitational waves. The simulations from the study took into account stellar evolution models including magnetic fields and cooling rates in the moments after core collapse. The simulations showed that the collapse events produce gravitational waves powerful enough to be detected from a distance of 50 million light years. The more powerful events already detected are ten times more powerful. 

The results are a surprise to the team that expected the results to show a jumble of waves that would be difficult to discern above the background noise of the universe. They even suggest that it’s possible that existing data may already hold observations of such events. 

To fully model the collapse events and how the gravity wave data may present itself, an estimated 1 million collapse simulations need to be run. Alas this is an expensive undertaking and unlikely to secure funding. Instead gravity wave astronomers are searching through existing data, looking for signals that are similar to the simulations the team have already run. One approach is to search for supernova events and to see if gravity wave observations detected any signals at the same time. The task however, is a daunting one but the hunt continues. 

Source : New Detectable Gravitational Wave Source From Collapsing Stars Predicted From Simulations

The post For Their Next Trick, Gravitational Wave Observatories Could Detect Collapsing Stars appeared first on Universe Today.

Boeing's troubled Starliner capsule is poised to return to Earth without any crew aboard on Sept. 6, NASA announced on Thursday (Aug. 29).

The search for extraterrestrial intelligence (SETI) has fascinated us for decades. Now a team of researchers have used the Murchison Widefield Array in Australia to scan great swathes of sky for alien signals. Unusually for a SETI project, this one focussed attention on 2,800 galaxies instead of stars within our own. They have been on the lookout for advanced civilisations that are broadcasting their existence using the power of an entire star. Alas they weren’t successful but its an exciting new way to search for alien intelligence. 

Our first attempts to search for alien intelligence began back in 1960 with Project Ozma. It was led by astronomer Frank Drake and used the 85 foot radio telescope at Green Bank in West Virginia. The aim was to try and detect alien radio signals from Epsilon Eridani and Tau Ceti, should they have existed. Alas they found nothing but it marked the first step in a scientific approach to search for extraterrestrial intelligence. Typically SETI tends to focus on electromagnetic signals such as radio waves an in particular unusual patterns that could suggest intentional communication. 

Radio telescopes monitor the sky at the Allen Telescope Array in California. Finding a signal from a distant civilization is one way we could experience first contact with ET. (SETI Institute Photo)

This recent attempt to try out a new approach was led by Dr Chenoa Tremblay of the SETI Institute and Prof. Steven Tingay from the Curtin University. The approach was to utilise the magnificent field of view of the Murchison Widefield Array (MWA) which allows one observation to cover 2,800 galaxies. Among them, there are 1,300 galaxies that we know the distance too. The MWA in Western Australia utilises low frequencies (100MHz) to probe the distant galaxies. 

By searching these galaxies for signs of alien signals we are actually looking for advanced civilisations. It’s one thing to be able to send radio signals across interstellar space, indeed we have been doing that for decades since the advent of radio communication. As radio signals propagate across space, they weaken and certainly could not traverse the immense distances between the galaxies. It’s just possible that advanced civilisations might have the technology to harness the power of their Sun and perhaps other stars in their galaxy to send signals powerful enough to travel the millions of light years between galaxies. 

I quite love the idea of advanced civilisations that may have developed the technology to transmit ‘technosignatures’ or signs of alien technology across the Universe but alas the study did not find any. Queue sad emoji

Solar sails are an exciting way to travel through the Solar System because they get their propulsion from the Sun. NASA has developed several solar sails, and their newest, the Advanced Composite Solar Sail System (or ACS3), launched a few months ago into low-Earth orbit. After testing, NASA reported today that they extended the booms, deploying its 80-square-meter (860 square feet) solar sail. They’ll now use the sail to raise and lower the spacecraft’s orbit, learning more about solar sailing.

“The Sun will continue burning for billions of years, so we have a limitless source of propulsion. Instead of launching massive fuel tanks for future missions, we can launch larger sails that use ‘fuel’ already available,” said Alan Rhodes, the mission’s lead systems engineer at NASA’s Ames Research Center, earlier this year. “We will demonstrate a system that uses this abundant resource to take those next giant steps in exploration and science.”

And for all you skywatchers out there, NASA said that given the reflectivity of the large sail and its position in orbit (about 1,000 km/600 miles) above Earth, ACS3 should be easily visible at times in the night sky. The Heavens Above website already has ACS3 listed on their page (just put in your location to see when to catch the solar sail passing over your area.) There should be info and updates available on social media, so follow NASA.gov and @NASAAmes on X and Instagram for updates.

ACS3 is part of NASA’s Small Spacecraft Technology program, which has the objective of deploying small missions that demonstrate unique capabilities rapidly. ACS3 launched in April 2024 aboard Rocket Lab’s Electron rocket from New Zealand. The spacecraft is a twelve-unit (12U) CubeSat built by NanoAvionics that’s about the size of a microwave oven. The biggest challenge designing and creating lightweight booms that could be small enough to fit inside the spacecraft while being able to extend to about 9 meters (30 ft) per side, and being strong enough to support the solar sail. The lightweight but strong composite carbon fiber boom system unrolled from the spacecraft to form rigid tubes that support the ultra-thin, reflective polymer sail.

This video shows how the booms work and the sail deploys:

When fully deployed, the sail forms a square that is about half the size of a tennis court. To change direction, the spacecraft angles its sails. Now with the boom deployment, the ACS3 team will perform maneuvers with the spacecraft, angling the sails and to change the spacecraft’s orbit.

The primary goal of the mission was to demonstrate boom deployment. With that now successfully achieved, the ACS3 team also hopes the mission will prove that their solar sail spacecraft can actually work for future solar sail-equipped science and exploration missions.?

This image shows the ACS3 being unfurled at NASA’s Langley Research Center. The solar wind is reliable but not very powerful. It requires a large sail area to power a spacecraft effectively. The ACS2 is about 9 meters (30 ft) per side, requiring a strong, lightweight boom system. Image Credit: NASA

Since ACS3 is a demonstration mission, the goal is to build larger sails that can generate more thrust. With these unique composite carbon fiber booms, the ACS3 system has the potential to support sails as large as 2,000 square meters, or about 21,500 square feet, or about half the area of a soccer field.

“The hope is that the new technologies verified on this spacecraft will inspire others to use them in ways we haven’t even considered,” Rhodes said.

And look for photos of the ACS3 fully deployed sail next week. The spacecraft has four cameras which captured a panoramic view of the reflective sail and supporting composite booms. NASA said that high-resolution imagery from these cameras will be available on Wednesday, Sept. 4.

NASA is providing updates on this mission on their Small Satellite Missions blog page.

The post NASA's New Solar Sail Extends Its Booms and Sets Sail appeared first on Universe Today.