This Week in Astronomy: Hidden Gravitational Waves, Dark Matter Black Holes and First Stars

<v Speaker 1>Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
<v Speaker 1>with our soothing Bedtime Astronomy podcast. Each episode offers a
<v Speaker 1>gentle journey through the stars, planets, and beyond, perfect for
<v Speaker 1>unwinding after a long day. Let's travel through the mysteries
<v Speaker 1>of the universe as you drift off into a peaceful
<v Speaker 1>slumber under the night sky. This week in Astronomy, hidden
<v Speaker 1>gravitational waves, dark matter, black holes in first stars. Super
<v Speaker 1>magnets may reveal hidden gravitational waves. Scientists have found a
<v Speaker 1>new way to possibly detect high frequency gravitational waves using
<v Speaker 1>powerful magnets. These waves are tiny ripples in space caused
<v Speaker 1>by massive cosmic events, and finding new ways to observe
<v Speaker 1>them could open up a whole new view of the universe.
<v Speaker 1>In the past, researchers tried using heavy metal cylinders known
<v Speaker 1>as well bars to catch gravitational waves. These bars would
<v Speaker 1>vibrate slightly when a wave passed through them, but the
<v Speaker 1>method only worked well when the wave matched the bar's
<v Speaker 1>natural vibration. If the wave was a different frequency, it
<v Speaker 1>didn't work so well. Now scientists are taking that old
<v Speaker 1>idea and improving it by using strong superconducting magnets instead
<v Speaker 1>of metal bars. These magnets are already being built for
<v Speaker 1>dark matter experiments, so they are very powerful and extremely precise.
<v Speaker 1>The magnets store a huge amount of magnetic energy, much
<v Speaker 1>more than the old metal bars could handle. That energy
<v Speaker 1>could make them sensitive enough to detect gravitational waves, especially
<v Speaker 1>in a range of frequencies that current detectors like ligo
<v Speaker 1>can't pick up. Well. Here's how it works. When a
<v Speaker 1>gravitational wave passes through the magnet, it causes tiny vibrations,
<v Speaker 1>almost like a soft shake. These vibrations stretch and squeeze
<v Speaker 1>the magnet in tiny ways. Because electric current flows through
<v Speaker 1>the wires inside the magnet, those tiny movements change the
<v Speaker 1>magnetic field just a little bit. That change creates a
<v Speaker 1>magnetic signal that can be picked up by extremely sensitive
<v Speaker 1>quantum sensors called squids. These sensors can detect even the
<v Speaker 1>smallest changes in magnetic fields. What's exciting is that this
<v Speaker 1>system creates magnetic signals directly, without needing to convert them
<v Speaker 1>from mechanical ones like the old Weber bars did. That
<v Speaker 1>makes the setup simpler and less likely to pick up
<v Speaker 1>unwanted noise. And because it works over a wide range
<v Speaker 1>of frequencies, especially from a few thousand up to ten
<v Speaker 1>million vibrations per second, it could detect waves that other
<v Speaker 1>detectors miss. The idea came from magnets already used in
<v Speaker 1>dark matter experiments such as dm radio and ADMXCFR. These
<v Speaker 1>projects use very large, very strong magnets to search for
<v Speaker 1>a particle called the Axian. Scientists realized that these same
<v Speaker 1>magnets could also be used to look for gravitational waves
<v Speaker 1>at the same time. While this new method probably won't
<v Speaker 1>be as sensitive as LIGO at lower frequencies, it might
<v Speaker 1>do better at higher ones frequencies where ligo doesn't work well.
<v Speaker 1>That would allow scientists to explore a whole new area
<v Speaker 1>of gravitational wave signals that we've never been able to
<v Speaker 1>study before. To make this work in practice, researchers will
<v Speaker 1>need to make sure the magnets are completely shielded from
<v Speaker 1>outside vibrations like cars driving by or footsteps in a lab.
<v Speaker 1>This is similar to what LIGO had to do when
<v Speaker 1>it was built. The research team is now expanding their
<v Speaker 1>work trying to figure out which kinds of gravitational waves
<v Speaker 1>these magnetic systems might be able to detect They're also
<v Speaker 1>looking into even better quantum sensors that could improve the
<v Speaker 1>technology even further. If it works, this new approach could
<v Speaker 1>give us a brand new way to listen to the universe.
<v Speaker 1>Hawking radiation may reveal dark matter black holes. Scientists may
<v Speaker 1>be on the brink of uncovering one of the greatest
<v Speaker 1>mysteries of the universe, the true nature of dark matter.
<v Speaker 1>A new study proposes an innovative method for detecting primordial
<v Speaker 1>black holes, extremely ancient and compact objects that may have
<v Speaker 1>formed shortly after the Big Bang. The idea is to
<v Speaker 1>look for these black holes, not through indirect cosmic effects
<v Speaker 1>or background radiation, as has traditionally been attempted, but by
<v Speaker 1>directly observing their radiation as they pass through our own
<v Speaker 1>solar system. This radiation, known as Hawking radiation, is a
<v Speaker 1>theoretical phenomenon in which black holes slowly emit particles due
<v Speaker 1>to quantum effects near their event horizons. The brilliance of
<v Speaker 1>this method lies in the fact that the amount of
<v Speaker 1>radiation emitted by a black hole is inversely related to
<v Speaker 1>its mass, meaning the smaller the black hole, the stronger
<v Speaker 1>the radiation signal it produces. Primordial black holes, which are
<v Speaker 1>thought to be much smaller than the stellar black holes
<v Speaker 1>formed by collapse stars, could be radiating detectable levels of
<v Speaker 1>energy if they are passing near us in space. Dark matter,
<v Speaker 1>the invisible substance that accounts for about eighty five percent
<v Speaker 1>of all matter in the universe, has never been directly observed.
<v Speaker 1>Scientists only know it exists because of its gravitational influence
<v Speaker 1>on galaxies and cosmic structures, yet its exact composition remains unknown.
<v Speaker 1>Among the more intriguing possibilities is that dark matter might
<v Speaker 1>be made up of these ancient primordial black holes. If
<v Speaker 1>that's true, then detecting just one of them directly would
<v Speaker 1>be a massive breakthrough. What the researchers propose is that
<v Speaker 1>as one of these small black holes SIPs through the
<v Speaker 1>Solar System, it should emit Hawking radiation that includes a
<v Speaker 1>wide range of parts articles, neutrinos, photons, and importantly for
<v Speaker 1>this study, positrons, which are the antimatter version of electrons.
<v Speaker 1>Positrons were chosen because they can be effectively detected by
<v Speaker 1>the Alpha magnetic Spectrometer AMS, a highly sensitive instrument mounted
<v Speaker 1>on the International Space Station. The AMS already collects positron
<v Speaker 1>data every day, making it an ideal tool to test
<v Speaker 1>this new theory without needing to build new instruments. The team,
<v Speaker 1>led by Alexandro pe Klipfel, carried out simulations to estimate
<v Speaker 1>how often such a primordial black hole might travel through
<v Speaker 1>the inner regions of our solar system and produce detectable radiation.
<v Speaker 1>Their findings suggest that this might happen roughly once a year,
<v Speaker 1>a surprisingly optimistic result considering how elusive these objects have
<v Speaker 1>been until now. This approach could eliminate the reliance on
<v Speaker 1>complex models of galactic behavior or background radiation, which are
<v Speaker 1>full of uncertainties. Instead, scientists could get direct in local
<v Speaker 1>evidence of these ancient black holes by identifying as sharp
<v Speaker 1>time dependent spike in positron counts as a PBH moves
<v Speaker 1>past Earth. It's like switching from listening for a faint
<v Speaker 1>background hum across a city to spotting a car driving
<v Speaker 1>past your window. Even more exciting is that this method
<v Speaker 1>may not be limited to positrons. The same principle could
<v Speaker 1>be used to search for other types of particles in
<v Speaker 1>hawking radiation, like gamma rays or X rays. These higher
<v Speaker 1>energy signals could allow scientists to detect even heavier pbhs,
<v Speaker 1>ones that are about the mass of a small asteroid
<v Speaker 1>or even a dwarf planet like series. That range of
<v Speaker 1>mass is especially interesting because it represents a key window
<v Speaker 1>in which pbhs could potentially make up all of the
<v Speaker 1>dark matter in the universe. By targeting that specific mass range,
<v Speaker 1>researchers might finally be able to determine whether these elusive
<v Speaker 1>black holes are the long sought missing matter of the cosmos.
<v Speaker 1>What's revolutionary about this proposal is that it shifts the
<v Speaker 1>entire strategy of dark matter detection. Instead of passively scanning
<v Speaker 1>the sky for subtle clues, scientists could actively hunt for
<v Speaker 1>individual dark matter candidates moving nearby. If successful, this method
<v Speaker 1>wouldn't just confirm the existence of primordial black holes. It
<v Speaker 1>would give us detailed insights into how many there are,
<v Speaker 1>how big they are, and how they're distributed through space.
<v Speaker 1>As our detection tools improve and new space observatories are launched,
<v Speaker 1>this strategy could bring us closer than ever to answering
<v Speaker 1>the question that has puzzled physicists and astronomers for decades.
<v Speaker 1>What is dark matter really made of? And if it
<v Speaker 1>turns out that tiny black holes ancient and cold drifting
<v Speaker 1>silently through space are the answer. We might finally see
<v Speaker 1>the invisible architecture that holds the universe together. First stars
<v Speaker 1>may be found in polluted galaxies. Population three stars or
<v Speaker 1>Pop three stars, are some of the most mysterious and
<v Speaker 1>important objects in astronomy. These stars are believed to be
<v Speaker 1>the very first generation ever formed in the universe, made
<v Speaker 1>entirely from the basic elements created in the Big Bang,
<v Speaker 1>mainly hydrogen and helium. They had no heavier elements, which
<v Speaker 1>astronomers call metals, because none had been made yet. Since
<v Speaker 1>these stars came before anything else, they are thought to
<v Speaker 1>have been very different from any stars we see today,
<v Speaker 1>possibly hundreds of times more massive than our Sun. They
<v Speaker 1>represent a key piece in the story of how the
<v Speaker 1>universe evolved from something simple into the complex and rich
<v Speaker 1>cosmos we now observe. Even with advanced tools like the
<v Speaker 1>James Webspace Telescope JWST, astronomers still haven't found clear evidence
<v Speaker 1>of these ancient stars. Have looked for completely pure galaxies,
<v Speaker 1>places with no signs of heavy elements at all. Scientists
<v Speaker 1>thought that by finding galaxies made only of hydrogen and helium,
<v Speaker 1>they could finally spot Population three stars. But this approach
<v Speaker 1>has a problem. It's too narrow. The window to catch
<v Speaker 1>these stars before they become polluted by supernova explosions is
<v Speaker 1>extremely short, making it very hard to observe them at
<v Speaker 1>the right moment. Now, a group of researchers led by
<v Speaker 1>elk Orusta from a university in Italy has proposed a
<v Speaker 1>new way of thinking. Instead of looking for galaxies that
<v Speaker 1>are perfectly clean and metal free, they suggest we should
<v Speaker 1>focus on galaxies that have just started to become polluted.
<v Speaker 1>When the first generation of massive stars has already begun
<v Speaker 1>exploding and spreading heavy elements into the surrounding gas, but
<v Speaker 1>some of the original population three stars are still shining,
<v Speaker 1>this phase, called the self polluted phase, may actually be
<v Speaker 1>the best time to find these early stars. It offers
<v Speaker 1>a wider window for detection and could explain why they've
<v Speaker 1>been so hard to spot until now. During this transitional time,
<v Speaker 1>even though the stars themselves are still metal free, the
<v Speaker 1>surrounding gas already carries the chemical fingerprints of the first
<v Speaker 1>supernova explosions. This means astronomers can detect specific light signals
<v Speaker 1>from the gas, like glowing lines produced by metals, while
<v Speaker 1>the stars inside are still the original pristine population three stars.
<v Speaker 1>This changes the whole strategy. Instead of waiting for a
<v Speaker 1>short lived, perfectly clean galaxy to appear, scientists can look
<v Speaker 1>for the telltale signs of this hybrid phase, which lasts
<v Speaker 1>longer and is easier to detect. The research team also
<v Speaker 1>discovered that a key sign of these early galaxies, strong
<v Speaker 1>helium emission, can last up to twenty million years. That
<v Speaker 1>may not seem like much, but in astronomy it's a
<v Speaker 1>big improved over earlier expectations. Even better, this helium signature
<v Speaker 1>can still be seen during the phase when both first
<v Speaker 1>generation and second generation stars are present, giving researchers more
<v Speaker 1>time and more chances to observe these rare systems. To
<v Speaker 1>help with the search, the scientists developed a set of
<v Speaker 1>new tools that look for specific signals in the ultraviolet
<v Speaker 1>part of the spectrum. They focus on patterns involving elements
<v Speaker 1>like oxygen and hydrogen, using the ratio between certain light
<v Speaker 1>emissions to find likely candidates. This method was applied to
<v Speaker 1>data from the JWST's deep space survey called JADES, and
<v Speaker 1>it worked surprisingly well. They found nine galaxy candidates that
<v Speaker 1>may contain a large population more than twenty five percent
<v Speaker 1>of metal free stars, which as far more than previous
<v Speaker 1>efforts had managed to identify. This approach is a major
<v Speaker 1>shift in how astronomers search for the universe's first stars.
<v Speaker 1>Instead of looking for what's missing, which is difficult and uncertain,
<v Speaker 1>this method looks for the presence of specific, measurable signs
<v Speaker 1>that can be clearly identified. If confirmed, these galaxies could
<v Speaker 1>reveal a great deal about how the first heavy elements
<v Speaker 1>were created and spread across the early universe. They could
<v Speaker 1>also help scientists understand how the universe changed from being
<v Speaker 1>made mostly of hydrogen and helium to becoming chemically rich
<v Speaker 1>and complex, full of the elements that make up stars, planets,
<v Speaker 1>and life itself. To do before m