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Remote tribes in Papua New Guinea were ravaged in the 20th century by kuru, which was spread when people ate their dead relatives as part of funeral rituals – but some individuals may have had genetic resistance to the condition

Remote tribes in Papua New Guinea were ravaged in the 20th century by kuru, which was spread when people ate their dead relatives as part of funeral rituals – but some individuals may have had genetic resistance to the condition

First, a quote:

“Just consider how absurd it would be to reverse the logic of human shields in this case: Imagine the Israelis using their own women and children as human shields against Hamas. Recognize how unthinkable this would be, not just for the Israelis to treat their own civilians in this way, but for them to expect that their enemies could be deterred by such a tactic, given who their enemies actually are.

Again, it is easy to lose sight of the moral distance here—which is strange. It’s like losing sight of the Grand Canyon when you are standing right on the edge of it. Take a moment to actually do the cognitive work: Imagine the Jews of Israel using their own women and children as human shields. And then imagine how Hamas, or Hezbollah, or al-Qaeda, or ISIS, or any other jihadist group would respond. The image you should now have in your mind is a masterpiece of moral surrealism. It is preposterous. It is a Monty Python sketch where all the Jews die.

Do you see what this asymmetry means? Can you see how deep it runs? Do you see what it tells you about the ethical difference between these two cultures?” —Sam Harris  \(audio is here)

***********************

Now, here is a simple question—or rather questions—prompted by my reading the readers’ thoughts in the discussion yesterday, “What does the U.S. want with Israel?”

How come no country in the world, save Israel, is calling for Hamas to surrender, lay down its arms, and release the hostages? That is the simplest way to end the war: no more Hamas, no more civilians killed, no more soldiers of the IDF killed, the hostages get to go home, and so on. It’s not complicated! (Of course how to run Gaza afterwards is complex and vexing, but first the war has to come to and end, and with a victory for Israel.)

And why is only Israel asking for this solution given that Hamas is a terrorist organization sworn to extirpate Israel and kill Jews, given that Hamas started this whole mess, and given that Hamas is even promoting the killing of more Palestinians, as well as members of NGOs, as a tactic to raise the world’s ire against Israel? How come the UN, the EU, and other Western governments aren’t pressuring Hamas? It is only Israel who gets pressured—to the extent that America is now telling Israel how to run the war, how to run its elections, and for heaven’t sake do not under any condition go into Rafah.

The answer to these questions is simple: Biden has become spineless and wants to win reelection, which he thinks he can’t do if he wholeheartedly supports Israel. And for the rest of the world, they simply want Israel to disappear, but except for some Muslim states they can’t say that out loud. (I’m not saying they want all the Jews killed, only that they don’t want Israel to exist.)

What a pity that Israel is in this largely on its own, while the rest of the world kowtows and grovels before Hamas! Yahweh knows, Israel is not perfect. But it’s a far sight better than Hamas and, as Sam Harris has emphasized, who you support in this conflict is a clear-cut moral question. Sadly, the world seems to have lost its moral compass.

Today we have the seventh and final installment of Robert Lang‘s recent trip to Antarctica in a small boat, and there are videos as well as photos. Robert’s notes are indented, and you can enlarge the photos by clicking on them.

Antarctica Part 7: Other Wildlife

Birds—penguins and flyers—and mammals—pinnipeds and cetaceans—are the stars of the Antarctic, but there is plenty of other wildlife to be seen if one looks carefully. Underpinning the entire Antarctic ecosystem is the Antarctic krill (Euphausia superba), whose total biomass is estimated to be half a billion metric tons. While we often saw animals feeding on them in the open water, we could only infer their presence from the feeding behavior; they’re too small to see (from a shallow angle, that is—overhead imagery has captured vast swarms). But we did find one in a tidepool. They’re tiny: just a few cm long.

Even smaller, and lower-down on the food chain, are copepods (class Copepoda), seen here also in a tidepool along with some red algae (Phyllophora sp.). These are about the size of a grain of rice.

Copepods and krill both eat phytoplankton; krill also eat copepods. Another of their predators is the smooth comb jelly (phylum Ctenphora, order Beroidae). We saw this one swimming just below the surface near our Zodiac; the boat driver successfully maneuvered to let people on both sides of the boat see the comb jelly while avoiding the outboard motor turning it into comb marmalade.

The shoreline of the Peninsula and its islands tends to be pretty barren, as the rocks are regularly pounded by ice and waves, but we saw an Antarctic sea urchin (Sterechinus neumeyeri) tucked into a crevice just at the waterline.

In the bay of Deception Island (the volcanic caldera), we saw quite a few brittle stars (class Ophiuroidea) washed up dead. Since there were warm-water vents all along the shore, we wondered if it just got too hot for them.

On shore, there’s not much permanent life, but there’s plenty of residue of prior life, including quite a few relics of the whaling days—not just human relics, but also whale bones that were left behind. Here’s an old whaling boat with some whale vertebrae in the foreground.

There are only two vascular plants in Antarctica, but there’s quite a range of lichen to be found on the rocks. These are two from King George Island, one with cup-like stalks, and another bringing a splash of bright color to the normally gray landscape.

I’ll close with an image of the not-terribly-elusive Red Penguin; we saw several flocks over the course of two weeks, typically waddling along their age-old trackways after migrating there from their giant floating rookeries. We saw them at some remove several times, but kept our own respectful distance, not wanting to disrupt their natural behaviors.

And this brings our Antarctic journey to an end.

2023 wasn't just the hottest year on record by far, it also saw record glacier loss, sea level rise, ocean heat and sea ice loss, says World Meteorological Organization report

After my post last week about familiar and unfamiliar standing waves — the former famous from musical instruments, the latter almost unknown except to physicists (see Chapter 17 of the book) — I got a number of questions. Quite a few took the form, “Surely you’re joking, Mr. Strassler! Obviously, if you have a standing wave in a box, and you remove the box, it will quickly disintegrate into traveling waves that move in opposite directions! There is no standing wave without a container.”

Well, I’m not joking. These waves are unfamiliar, sure, to the point that they violate what some readers may have learned elsewhere about standing waves. Today I’ll show you animations to prove it.

When a Standing Wave Loses Its Box

The animations below show familiar and unfamiliar standing waves inside small boxes (indicated in orange). The boxes are then removed, leaving the waves to expand into larger boxes. What happens next is determined by straightforward math; if you’re interested in the math, see the end of this post.

Though the waves start out with the same shape, they have different vibrational frequencies; the unfamiliar wave vibrates ten times faster. Each wave vibrates in place until the small box is taken away. Then the familiar wave instantly turns into two traveling waves that move in opposite directions at considerable speed, quickly reaching and reflecting off the walls of the new box. Nothing of the original standing wave survives, except that its ghost is recreated for a moment when the two traveling waves intersect.

The unfamiliar wave, however, has other plans. It continues to vibrates at the center of the box for quite a while, maintaining its coherence and only slowly spreading out. As the traveling waves from the familiar standing wave are hitting the walls of the outer box, the unfamiliar wave is still just barely tickling those walls. Only at the very end of the animation is this wave even responding of the presence of the box.

A familiar standing wave vibrates within a small box. When the small box is removed, the wave decomposes into traveling waves that reflect off the walls of the larger box. Animation made using Mathematica. Same as at left, but for an unfamiliar standing wave. For the same shape, it initially has a higher frequency, and it spreads much more slowly when the smaller box is removed. Animation made using Mathematica.

To fully appreciate this effect, imagine if I’d made the ratio between the two waves’ frequencies one thousand instead of ten. Then the unfamiliar wave would have taken a thousand times longer than the familiar wave to completely spread across its box. However, I didn’t think you’d want to watch such boring animations, so I chose a relatively small frequency ratio.

Now let’s put in some actual numbers, to appreciate how impressive this becomes when applied to real particles.

Photons and Electrons in Boxes

Let’s take an empty box (having removed the air inside it) whose sides are a tenth of a meter (about three inches) long. If I put a standing-wave photon (a particle of light) into it, that wave will have a frequency of 3 billion cycles per second. That puts it in the microwave range.

If I then release the photon into a box a full meter across, the photon’s wave will turn into traveling pulses, as my first animation showed. Moving at the speed of light, the pulses will reach the walls of the larger box in about 1.5 billionths of a second (1.5 nanoseconds.) This is what we are taught to expect: without the walls, the standing wave can’t survive.

But if I put a standing-wave electron in a box a tenth of a meter across, it will have a frequency of 800 billion billion cycles per second. That’s not a typo — I really do mean 800 Billion-Billion, which is enormously faster vibration than for a microwave photon.

Correspondingly, when the electron is released from its original box to a larger one a meter across, it will simply remain vibrating at the center of the box, in an extreme version of the second animation. The edges of the electron’s wave will expand, but no faster than a few millimeters per second. The amount of time it will take for its vibrating edges to reach out to the edges of the new box will be well over a minute.

From the electron’s perspective, vibrating once every billionth of a trillionth of a second, this spreading takes almost forever. It’s a long time even for a human physicist. Most experiments on freely floating electrons, including those that measure an electron’s rest mass, take much less than a second. For many such measurements, the fact that an unconstrained electron is gradually spreading is of little practical importance.

Atoms are Boxes Too

Thus standing waves can exist without walls for a quite a while, if they are sufficiently broad to start with. The word broad is important here. From smaller boxes, or from atoms, the spreading is more rapid; an electron liberated from a tiny hydrogen atom can grow to the size of a room in the blink of an eye. The larger the electron’s initial container, the wider the electron’s initial standing wave will be, and the more slowly it will spread.

This pattern might remind you of the famous and infamous uncertainty principle. And well it should.

For the math behind this, read this article (the fourth of this series); the familiar waves satisfy what I called Class 0 wave equations, while the unfamiliar ones satisfy Class 1 wave equations. If you read to the end of the series, you’ll see the direct connection of these two classes of waves with photons and electrons, and more generally with particles of zero and non-zero rest mass.

Nearly 70 "forever chemicals", also known as PFAS, are commonly found in materials that come into contact with food, some of which have been linked to negative health outcomes

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The heating elements in vapes can release toxic metals. Now an analysis of cannabis vaping liquids shows metals like lead are present at dangerous levels – even before the vape is used

This controversial treatment for PTSD involves moving the eyes side to side.

Science: Figuring things out is better than making things up. A tee shirt I recently saw. Except… In a recent post Mayo Clinic Promotes Reiki, Steve seemed surprised that the Mayo was offering Reiki. I don’t know. Maybe he was channeling Louie. I know the Mayo is a top hospital, but I trained in Minneapolis at Hennepin County and we would have […]

The post Best Hospital Eye Roll first appeared on Science-Based Medicine.

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The Holocaust is much discussed, much memorialized, and much portrayed. But there are major aspects of its history that have been overlooked.

Spanning the entirety of the Holocaust, this sweeping history deepens our understanding. Dan Stone—Director of the Holocaust Research Institute at Royal Holloway, University of London—reveals how the idea of “industrial murder” is incomplete: many were killed where they lived in the most brutal of ways. He outlines the depth of collaboration across Europe, arguing persuasively that we need to stop thinking of the Holocaust as an exclusively German project. He also considers the nature of trauma the Holocaust engendered, and why Jewish suffering has yet to be fully reckoned with. And he makes clear that the kernel to understanding Nazi thinking and action is genocidal ideology, providing a deep analysis of its origins.

Drawing on decades of research, The Holocaust: An Unfinished History upends much of what we think we know about the Holocaust. Stone draws on Nazi documents, but also on diaries, post-war testimonies, and even fiction, urging that, in our age of increasing nationalism and xenophobia, it is vital that we understand the true history of the Holocaust.

Dan Stone is Professor of Modern History and Director of the Holocaust Research Institute at Royal Holloway, University of London. He is the author or editor of numerous articles and books, including: Histories of the Holocaust (Oxford University Press); The Liberation of the Camps: The End of the Holocaust and its Aftermath (Yale University Press); and Concentration Camps: A Very Short Introduction (Oxford University Press). His new book is The Holocaust: An Unfinished History.

Shermer and Stone discuss:

• Why this book now? What is unfinished in the history of the Shoah?
• Holocaust denial: 20% of Americans under 30 who, according to a poll by The Economist, believe the Holocaust is a myth. Another 20% believe it is exaggerated
• Just as “Nazism was the most extreme manifestation of sentiments that were quite common, and for which Hitler acted as a kind of rainmaker or shaman”, suggests Stone, the defeat of his regime has left us with “a dark legacy, a deep psychology of fascist fascination and genocidal fantasy that people turn to instinctively in moments of crisis – we see it most clearly in the alt-right and the online world, spreading into the mainstream, of conspiracy theory”
• What was the Holocaust and why did it happen: intentionalism vs. functionalism
• Ideological roots of Nazism and German anti-Semitism
• “ideology, understood as a kind of phantasmagorical conspiracy theory, as the kernel of Nazi thinking and action”
• From ideas to genocide: magical thinking
• Blood and soil
• Hitler’s willing executioners
• The Holocaust as a continent-wide crime
• Motivations of the executioners
• Polish law prohibiting the accusation of Poles complicit in the Holocaust
• Industrial genocide vs. low-tech mass murder
• The banality of evil
• Nearly half of the Holocaust’s six million victims died of starvation in the ghettos or in “face-to-face” shootings in the east.
• Jews were constrained by a profusion of demeaning legislation. They were forbidden to keep typewriters, musical instruments, bicycles and even pets. The sheer variety of persecution was bewildering. It was also chillingly deceptive, persuading some law-abiding Jews that survival was a matter of falling into line. Stone quotes the wrenching letter of a woman reassuring her loved one that getting transported to Theresienstadt, in German-occupied Czechoslovakia, might be better than living in Germany. “My future place of residence represents a sort of ghetto,” she explained. “It has the advantage that, if one obeys all the rules, one lives in some ways without the restrictions one has here.”
• Wannsee Conference of Jan. 20, 1942
• In March 1942, “75 to 80 percent of the Holocaust’s victims were still alive.” Eleven months later, “80 percent of the Holocaust’s victims were dead.”

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Universe Today has examined the importance of studying impact craters, planetary surfaces, exoplanets, astrobiology, solar physics, comets, and planetary atmospheres, and how these intriguing scientific disciplines can help scientists and the public better understand how we are pursuing life beyond Earth. Here, we will look inward and examine the role that planetary geophysics plays in helping scientists gain greater insight into our solar system and beyond, including the benefits and challenges, finding life beyond Earth, and how upcoming students can pursue studying planetary geophysics. So, what is planetary geophysics and why is it so important to study it?

“Planetary geophysics is the study of how planets and their contents behave and evolve over time,” Dr. Marshall Styczinski, who is an Affiliate Research Scientist at the Blue Marble Space Institute of Science, tells Universe Today. “It is essentially the study of What Lies Below, focusing on what we can’t see and how it relates to what we can see and measure. Most of the planets (including Earth!) are hidden from view—geophysics is how we know everything about the Earth below the deepest we have dug down!”

As its name implies, geophysics is the study of understanding the physics behind geological processes, both on Earth and other planetary bodies, with an emphasis on interior geologic processes. This is specifically useful for planetary bodies that are differentiated, meaning they have several interior layers resulting from heavier elements sinking to the center while the lighter elements remain closer to the surface. 

The planet Earth, for example, is separated into the crust, mantle, and core, with each having its own sub-layers, and understanding these interior processes help scientists piece together what the Earth was like billions of years ago and even make predictions regarding the planet’s environment in the far future. These interior processes drive the surface processes, including volcanism and plate tectonics, both of which are responsible for maintaining the Earth’s temperature and recycling materials, respectively. So, what are some of the benefits and challenges of studying planetary geophysics?

Dr. Styczinski tells Universe Today, “Geophysics gives us the tools to determine what exists beneath the visible surface of planetary bodies (planets, moons, asteroids, etc.). It’s our only way to learn about what we can’t see! Finding out what is inside a planet, and under what conditions, like how much pressure and heat for each layer, helps us build a history for the planet and know how it will continue to change over time.”

In contrast, Dr. Styczinski also emphasizes to Universe Today the challenges, noting the difficulty in reproducing geologic conditions that occur over millions of years, even with the most sophisticated laboratories in the world, due to their slow movements over vast amounts of time. Additionally, he notes that particle accelerators are sometimes required to reproduce the extreme conditions within gas giants, which are also differentiated, though with gas and liquid layers, as opposed to rock. 

Artist’s illustration of gas giant interiors. (Credit: NASA/Lunar And Planetary Institute)

But Earth is not the only rocky world in our solar system that exhibits differentiation, as all four rocky planets (Mercury, Venus, Earth, and Mars) exhibit some form of interior layering that has occurred over billions of years, though at smaller scales due to their sizes. In addition to the planets, many rocky moons throughout the solar system also exhibit differentiation, including Jupiter’s Galilean moons, Io, Europa, Ganymede, and Callisto, and several of Saturn’s moons, including Titan, Enceladus, and Mimas. Of those moons, Europa, Titan, and Enceladus are currently targets for astrobiologists, as Europa and Enceladus have been confirmed to possess interior liquid water oceans, with Titan presenting strong evidence, as well. Additionally, Titan is the only moon with a dense atmosphere, and like Earth, it likely has interior geophysics driving it. But what can planetary geophysics teach us about finding life beyond Earth?

Artist’s illustration of terrestrial (rocky) planet interiors. (Credit: NASA) Artist’s illustration of the interior of Jupiter’s icy moon, Europa. (Credit: NASA/JPL-Caltech/Michael Carroll) Artist’s illustration of the interior of Saturn’s icy moon, Enceladus. (Credit: NASA/JPL-Caltech)

“We’ve learned from studying Mars that the surfaces of planets can be quite hostile to life as we know it,” Dr. Styczinski tells Universe Today. “If and when we are able to find life elsewhere in the solar system that we didn’t bring there ourselves, it will probably be found beneath the surface, where it can be protected from the harsh environment at the surface. Geophysics gives us the means to plan for expeditions into the subsurface, and the only method of finding liquid water that’s hidden from view on icy moons. These are the best places we know of to look for life beyond Earth.”

The reason why the surface of Mars is inhospitable to life as we know it is due to its lack of a thick atmosphere, which is responsible for preventing the Sun’s charged particles in the solar wind from reaching the planetary surface. While Mars once had a powerful magnetic field, Dr. Styczinski notes to Universe Today that “Some researchers think magnetic fields can actually strip away the atmosphere”, while quickly noting this “is a topic of fierce debate.” Mars once had a thicker atmosphere, which was lost along with its magnetic field over billions of years as the Red Planet’s interior cooled.

In addition to our solar system, Dr. Styczinski tells Universe Today that planetary geophysics also does an excellent job of helping scientists better understand exoplanets, specifically multi-planet systems like our own. While no exoplanet surface has yet been imaged, better understanding the geophysical processes of planetary bodies within our solar system helps scientists gain insights into how these same processes could occur on planets throughout the cosmos, including the magnetic field, as well. 

A planet’s magnetic field is driven by the internal processes occurring in its outer core, which for Earth is comprised of churning, liquid metal fluid, whereas the inner core is a solid ball of compressed metal. As this outer core’s fluid churns and circulates, it creates electrical currents that produce the massive magnetic field that envelopes our small, blue world in a bubble of protection from harmful space weather. The Earth’s magnetic field traps charged particles in radiation belts in space nearby. The way the magnetic field protects our planet can be seen during magnetic storms from the Sun, when the magnetosphere bends and flexes in response, sending particles from these radiation belts close to the surface in the high northern and southern latitude regions. There, they interact with the Earth’s atmosphere to produce the breathtaking auroras often observed in Alaska, the Nordic countries, and Antarctica. 

Rendition displaying the solar wind interacting with Mars, which does not possess a magnetic field, versus Earth and its very active magnetic field. The lack of a magnetic field means Mars is constantly bombarded by space weather, exposing its surface to harmful radiation, whereas Earth’s surface is almost entirely protected, allowing life to both survive and thrive across the planet. (Credit: NASA)

However, while the Earth’s magnetic field is impressive, it’s only fitting that the largest planet in the solar system, Jupiter, equally has the largest magnetic field, whose “tail” extends as far as Saturn’s orbit, or approximately 400 million miles. Additionally, the internal processes responsible for generating magnetic fields on gaseous planets like Jupiter, Saturn, Uranus, and Neptune could be starkly different than on Earth. Therefore, given all of these variables and processes, what is the most exciting aspect of planetary geophysics that Dr. Styczinski has studied during his career?

“The part of planetary geophysics that I find the most exciting is using the invisible magnetic field to sense subsurface oceans,” Dr. Styczinski tells Universe Today. “I continue to be blown away by how it all works when I really think about it. Salty ocean waters partially reflect the fields they are exposed to from their parent planet, as in Jupiter and its moon Europa. We use these measurements along with laboratory studies here on Earth and geophysics to understand the material layers inside Europa to work out the properties of the ocean. It still blows my mind that this process works as well as it does.”

Like most scientific fields, planetary geophysics encompasses a myriad of scientific disciplines and backgrounds with the goal of answering the universe’s toughest questions through constant collaboration and innovation. Geophysics is a combination of geology and physics but also incorporates mathematics, chemistry, atmospheric science, seismology, mineralogy, and many others with the goal of better understanding the interior processes of the Earth and other planetary bodies throughout the solar system and beyond. Therefore, what advice can Dr. Styczinski offer upcoming students who wish to pursue studying planetary geophysics?

“There are many paths into geophysics, and many different things to study and ways to study them,” Dr. Styczinski tells Universe Today. “Your past studies don’t have to be specific to geophysics or even involve geology at all. Perhaps the most productive move you can make is to ask for help, especially from someone studying a topic that interests you. Computer programming skills are invaluable. I recommend learning Python—it’s free and widely used all across science. There are many tutorials available, also for free. While not all geophysics will require a lot of programming, I think all geophysicists will benefit from having those skills.”

How will planetary geophysics help us better understand our place in the cosmos in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

The post Planetary Geophysics: What is it? What can it teach us about finding life beyond Earth? appeared first on Universe Today.

Leafhoppers, a common backyard insect, secrete and coat themselves in tiny mysterious particles that could provide both the inspiration and the instructions for next-generation technology, according to a new study. In a first, the team precisely replicated the complex geometry of these particles, called brochosomes, and elucidated a better understanding of how they absorb both visible and ultraviolet light.

Leafhoppers, a common backyard insect, secrete and coat themselves in tiny mysterious particles that could provide both the inspiration and the instructions for next-generation technology, according to a new study. In a first, the team precisely replicated the complex geometry of these particles, called brochosomes, and elucidated a better understanding of how they absorb both visible and ultraviolet light.

A new report uncovers how hydrogen gas, the energy of the future, provided energy in the past, at the origin of life 4 billion years ago. Hydrogen gas is clean fuel. It burns with oxygen in the air to provide energy with no CO2. Hydrogen is a key to sustainable energy for the future. Though humans are just now coming to realize the benefits of hydrogen gas (H2 in chemical shorthand), microbes have known that H2 is good fuel for as long as there has been life on Earth. Hydrogen is ancient energy.

Quasars are the brightest objects in the Universe. The most powerful ones are thousands of times more luminous than entire galaxies. They’re the visible part of a supermassive black hole (SMBH) at the center of a galaxy. The intense light comes from gas drawn toward the black hole, emitting light across several wavelengths as it heats up.

But quasars are more than just bright ancient objects. They have something important to show us about the dark matter.

Large galaxies have supermassive black holes at their centers. Even those only casually familiar with space know that black holes can suck everything in, even light. But as black holes draw nearby gas towards themselves, the gas doesn’t all go into the hole, past the event horizon and into oblivion. Instead, much of the gas forms a rotating accretion disk around the black hole.

SMBHs aren’t always actively drawing material to them, an act known as ‘feeding.’ But when an SMBH is actively feeding, it’s called an active galactic nucleus (AGN.) When the material in the disk rotates, it heats up. As it heats, it emits different wavelengths of electromagnetic radiation. It can also emit jets.

When astronomers first began to detect this light, they only knew they were seeing objects that emitted radio waves. The name quasar means quasi-stellar radio source. But as time went on astronomers learned more, and the term active galactic nucleus was adopted. The term quasar is still used, but they’re now a sub-class of AGN that are the most luminous AGN.

Quasars inhabit galaxies that are surrounded by enormous haloes of dark matter. Astronomers think there’s a link between the dark matter haloes (DMH) and the quasars. The DMH may direct more matter toward the center of the galaxy, feeding the SMBH and igniting a quasar, and even aiding the formation of more massive galaxies.

Artist rendering of the dark matter halo surrounding our galaxy. Credit: ESO/L. Calçada

A team of researchers has created a new catalogue of quasars that will be a powerful tool for probing quasars, DMHs, and SMBHs. Their results are in a new paper in The Astrophysical Journal titled “Quaia, the Gaia-unWISE Quasar Catalog: An All-sky Spectroscopic Quasar Sample.” The lead author is Kate Storey-Fisher, a postdoctoral researcher at the Donostia International Physics Center in Spain.

“This quasar catalogue is different from all previous catalogues in that it gives us a three-dimensional map of the largest-ever volume of the universe,” said map co-creator David Hogg, a senior research scientist at the Flatiron Institute’s Center for Computational Astrophysics in New York City and a professor of physics and data science at New York University. “It isn’t the catalogue with the most quasars, and it isn’t the catalogue with the best-quality measurements of quasars, but it is the catalogue with the largest total volume of the universe mapped.”

This infographic helps explain Quaia, the new catalogue of 1.3 million quasars. Image Credit: ESA/Gaia/DPAC; Lucy Reading-Ikkanda/Simons Foundation; K. Storey-Fisher et al. 2024

The fact that the new catalogue captures the largest total volume of the Universe mapped and all the quasars in that space is key to understanding its purpose. It’s not meant as a survey that captures the largest number of quasars. The catalogue is meant to be a tool astrophysicists can use to understand the relationships between quasars, dark matter, black holes, and galaxies.

They call their catalogue Quaia because the data comes from the ESA’s Gaia spacecraft. Gaia’s mission is to map about one billion objects in the Milky Way, mostly stars. And it’s going about its mission with extreme accuracy. But among the multitudes of stars Gaia has mapped is a large number of quasars well beyond the Milky Way. That generated the name “Quaia.”

“We were able to make measurements of how matter clusters together in the early universe that are as precise as some of those from major international survey projects — which is quite remarkable given that we got our data as a ‘bonus’ from the Milky Way–focused Gaia project,” Storey-Fisher says.

Dark matter tends to clump in haloes around galaxies, and studying the distribution of quasars can help explain the distribution of dark matter. In the large scale of the Universe, dark matter is organized as a web, and the catalogue of quasars helps map that web.

The Cosmic Microwave Background (CMB), a strong piece of evidence for the Big Bang, is also part of this. As the light from the CMB travels toward us through space, the dark matter web’s massive gravitational power bends the light. Scientists can compare the CMB light we receive with the map of quasars and compare the two. The comparisons will them about the relationship between dark matter and quasars and how matter clumps together in the Universe.

Since quasars trace the cosmic web, their distribution gives information about the web that other sources can’t. For example, it can trace the distribution of matter at higher redshifts than galaxies can. And since it’s space-based, it avoids some of the data contamination that other quasar surveys suffer from, such as the Sloan Digital Sky Survey (SDSS.)

This is not the first quasar map/catalogue to be created. There are several others, including one from the Sloan Digital Sky Survey.

This figure shows five different quasar maps created by scientists using different data and methodologies. The creators of Quaia say that its redshifts are more accurate than the others, along with other properties. Image Credit: K. Storey-Fisher et al. 2024

As the animation below shows, Quaia is more complete than the SDSS’s DR16Q, the SDSS’s quasar catalogue that accompanied its data release 16.

via GIPHY

Though the Gaia mission itself doesn’t generate many of its own headlines, it’s at the foundation of modern space science. Its data is behind lots of published research.

“This quasar catalogue is a great example of how productive astronomical projects are,” says Hogg. “Gaia was designed to measure stars in our own galaxy, but it also found millions of quasars at the same time, which give us a map of the entire universe.”

Now, the new Quaia catalogue is playing a similar role. The data it contains is already being used by other researchers.

“It has been very exciting to see this catalogue spurring so much new science,” Storey-Fisher says. “Researchers around the world are using the quasar map to measure everything from the initial density fluctuations that seeded the cosmic web to the distribution of cosmic voids to the motion of our solar system through the universe.”

The post This New Map of 1.3 Million Quasars Is A Powerful Tool appeared first on Universe Today.

Only eating within an 8-hour window is associated with a significantly higher risk of heart disease-related death compared with eating over 12 to 16 hours

The exoplanet census now stands at 5,599 confirmed discoveries in 4,163 star systems, with another 10,157 candidates awaiting confirmation. So far, the vast majority of these have been detected using indirect methods, including Transit Photometry (74.4%) and Radial Velocity measurements (19.4%). Only nineteen (or 1.2%) were detected via Direct Imaging, a method where light reflected from an exoplanet’s atmosphere or surface is used to detect and characterize it. Thanks to the latest generation of high-contrast and high-angular resolution instruments, this is starting to change.

This includes the James Webb Space Telescope and its sophisticated mirrors and advanced infrared imaging suite. Using data obtained by Webb‘s Near-Infrared Camera (NIRCam), astronomers with the MIRI mid-INfrared Disk Survey (MINDS) survey recently studied a very young variable star (PDS 70) about 370 light-years away with two confirmed protoplanets. After examining the system and its extended debris disk, they found evidence of a third possible protoplanet orbiting the star. These observations could help advance our understanding of planetary systems that are still in the process of formation.

The MINDS survey is an international collaboration consisting of astronomers and physicists from the Max-Planck-Institute for Astronomy (MPIA), the Kapteyn Astronomical Institute, the Space Research Institute at the Austrian Academy of Sciences (OAW-IFW), the Max-Planck Institute for Extraterrestrial Physics (MPE), the Centro de Astrobiología (CAB), the Institute Nazionale di Astrofisica (INAF), the Dublin Institute for Advanced Studies (DIAS), the SRON Netherlands Institute for Space Research, and multiple universities. The paper that describes their findings will appear in the journal Astronomy & Astrophysics.

This spectacular image from the SPHERE instrument on ESO’s Very Large Telescope is the first clear image of a planet caught in the very act of formation around the dwarf star PDS 70. Credit: ESO/A. Müller et al.

PDS 70 has been the subject of interest in recent years due to its young age (5.3 to 5.5 million years) and the surrounding protoplanetary disk. Between 2018 and 2021, two protoplanets planets were confirmed within the gaps of this disk based on direct imaging data acquired by sophisticated ground-based telescopes. This included the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) and GRAVITY instruments on the ESO’s Very Large Telescope (VLT) and the Atacama Large Millimeter/submillimeter Array (ALMA).

In recent years, the MINDS team has used Webb spectral data to perform chemical inventories on protoplanetary disks in multiple star systems. In a previous study based on data from Webb‘s Mid-Infrared Instrument (MIRI), the MINDS team detected water in the inner disk of PDS 70, located about 160 million km (100 million mi) or 1.069 AU from the star, a find that could have implications for astrobiology and the origins of water on rocky planets (like Earth). These results showcased Webb’s impressive capabilities and how it can observe the cosmos in infrared (IR) wavelengths inaccessible to ground-based observatories.

Valentin Christiaens, an F.R.S-FNRS Postdoctoral Researcher at the University of Liège and KU Leuven, was the lead author of this latest paper. “The advantage of Webb’s instruments is that they observe at infrared wavelengths that cannot be observed from the ground because of our atmosphere, which absorbs most of the infrared spectrum,” he told Universe Today via email. “Thanks to Webb we can obtain measurements of planets in formation (called protoplanets) in infrared, which allow us to better constrain our models of planet formation.”

For their latest study, the MINDS team examined PDS 70 using data from Webb‘s NIRCam as part of the MIRI Guaranteed Time Observations program on planet formation. Christiaens and his team were motivated to study PDS 70 further because previous research indicated the possible detection of a third protoplanet. This makes the system an ideal laboratory to study planet-disk interactions and search for accretion signatures. The presence of a possible third signal was detected in 2019 by a team using the VLT/SPHERE instrument but remained unconfirmed since.

This artist’s illustration shows a compact protoplanetary disk and an extended one. Credit: NASA, ESA, CSA, Joseph Olmsted (STScI)

One possible interpretation for this signal was that it traces a third planet. Using NIRCam data, Christiaens and his colleagues sought to redetect this signal and confirm that it was a third planet in the system. The JWST is especially well-suited to this task, thanks to its advanced optics and coronograph, which removes interference from Webb’s images by blocking the star’s light. He and his colleagues were also aided by advanced algorithms that help separate starlight from other point sources in orbit (like exoplanets) and debris disks. As Christiaens explained:

“The observation of another star, called a reference star, can be used to subtract the light from the star of interest and look for exoplanets there. In our study, we instead opted for a technique called “roll subtraction,” where two sequences of images are taken of the star of interest before and after the instrument is rotated, respectively, so that the position of an exoplanet has rotated in the two image sequences. From there, by subtracting the images of one sequence from those of the other, and vice versa, we can effectively get rid of the light of the star and make images of its environment – planets and disk.”

The team then combined their measurements with previous observations made with ground instruments and compared them to planetary formation models. From this, they could deduce the quantity of accumulated gas and dust around the protoplanet during the observation period. The quality of the images also allowed them to highlight a spiral arm of gas and dust supplying the second confirmed candidate (PDS 70 c), as predicted by the models. Lastly, they detected a bright signal consistent with a protoplanet candidate enshrouded in dust.

“What makes this candidate so interesting is that it could be in 1:2:4 resonance with planets b and c, already confirmed in the system (i.e., its orbital period will be almost exactly two times and four times shorter than that of b and c, respectively),” said Christiaens. This is precisely what happens with three of Jupiter’s Galilean Moons (Ganymede, Europa, and Io), which are also in a 1:2:4 resonance. The possibility of a star system with three planets in this orbital relationship would be a gold mine for astronomers. “However, more observations are needed before this resonance can be confirmed,” Christiaens added.

The evolutionary sequence of protoplanetary disks with substructures, from the ALMA CAMPOS survey. These wide varieties of planetary disk structures are possible formation sites for young protoplanets. Image Credit: Hsieh et al. in prep.

In addition to demonstrating Webb’s capabilities, these findings could help inform our current understanding of how planetary systems form and evolve. This is one of the main objectives of the JWST: to use its advanced infrared optics to probe young star systems where planets are still in the process of forming. This has been a high priority for astronomers ever since Kepler began detecting exoplanets that defied widely accepted theories of how planetary systems form and evolve. In particular, the detection of many gas giants orbiting closely to their suns (“Hot-Jupiters”) contradicted theories that gas giants form in the outer reaches of star systems.

By observing young star systems at different stages of formation, astronomers hope to test various theories about how the Solar System came to be. As Christiaens summarized:

“The migration of planets is thought to play a crucial role in the evolution of planetary systems and helps explain the diversity of systems found to date via indirect methods. In many mature systems, planets have been found to resonate with each other, suggesting that this migration did indeed take place in the past. In our case, we observe a very young system, still in formation, where the 2 known giant planets seem to be in resonance and where the third potential planet, if confirmed, would also be with the other two. In the case of the Solar System, we suspect that the migration and resonance capture of the giant planets probably also took place a very long time ago, [which could] explain their current configuration (Great Tack hypothesis). Here we are potentially observing it live in another system!”

Further Reading: arXiv

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