SPACE

How to Watch SpaceX Launch Space Force’s Spaceplane for the First Time

George Dvorsky
Fri, December 8, 2023 

The X-37B spaceplane.



The X-37B spaceplane.

For the first time, a SpaceX Falcon Heavy will attempt to deliver the Pentagon’s spaceplane to low Earth orbit. The mission marks the seventh for the mysterious spacecraft, aiming to expand the Space Force’s knowledge of the space environment and test new technologies.


The Falcon Heavy is slated to launch at 8:15 p.m ET on Sunday, December 10 from launch complex 39A at Kennedy Space Center in Florida. Both side boosters will attempt vertical landings shortly after launch (Falcon Heavy is essentially three Falcon 9 rockets strapped together). The event will be livestreamed on SpaceX’s account on X, previously known as Twitter.

The mission “will expand the United States Space Force’s knowledge of the space environment by experimenting with future space domain awareness technologies,” Space Force said in a statement. “These tests are integral in ensuring safe, stable, and secure operations in space for all users of the domain.”

For its seventh mission, the X-37B will operate in new orbital alignments and carry a NASA experiment named Seeds-2. This experiment will expose plant seeds to the harsh radiation environment of long-duration spaceflight, gathering data vital for future crewed missions.

The spaceplane’s previous mission, launched atop a ULA Atlas V rocket in May 2020, saw the spaceplane spend a record 908 days in orbit before landing at NASA’s Kennedy Space Center in November 2022. This mission included a service module that expanded the spacecraft’s capabilities, and hosting more experiments than any previous missions. Among these were the Naval Research Laboratory’s Photovoltaic Radio-frequency Antenna Module experiment and two NASA experiments studying the effects of space conditions on various materials.

This upcoming mission marks SpaceX’s 92nd for the year 2023, inching closer to CEO Elon Musk’s ambitious target of 100 launches within the year. With several weeks remaining, the company appears to be on track to potentially reach this significant milestone.

For more spaceflight in your life, follow us on X (formerly Twitter) and bookmark Gizmodo’s dedicated Spaceflight page.

Space Station Astronauts Find Desiccated Tomato After Blaming Colleague for Its Theft

Victor Tangermann
Thu, December 7, 2023 


Grand Theft Tomato

A scandal on board the International Space Station has finally been put to bed.

For months now, NASA astronaut Frank Rubio has been accused by his fellow crew members — in jest, they say, mostly at least —of eating a tiny tomato that was laboriously grown on board the space station.

But as it turns out, Rubio was innocent.

"Our good friend Frank Rubio, who headed home [already], has been blamed for quite a while for eating the tomato," NASA astronaut Jasmin Moghbeli said during a live stream celebrating the station's 25th anniversary.

"But we can exonerate him," she added in the footage, spotted by Space.com. "We found the tomato."
Crime and Punishment

Rubio flew to the space station on board a Soyuz spacecraft in September 2022 and made his return just over a year later due to delays caused by the same capsule starting to uncontrollably leak coolant. The unusual incident forced Russia's space program to send a replacement spacecraft, which ended up taking several months.

While he was on board the station, Rubio tended to an experiment dubbed Veg-05, which involved growing tiny Red Robin dwarf tomatoes.

In late March, astronauts were each given a share of the harvest tucked inside Ziploc bags. Rubio says his share, however, floated away before he could eat the fruits of his labor.

"I spent so many hours looking for that thing," Rubio said during a September livestream. "I'm sure the desiccated tomato will show up at some point and vindicate me, years in the future."

In October, two weeks after returning to the ground, Rubio told reporters that he spent "18 to 20 hours of my own time looking for" the errant tomato, as quoted by Space.com.

"The reality of the problem, you know — the humidity up there is like 17 percent," he added. "It's probably desiccated to the point where you couldn't tell what it was, and somebody just threw away the bag."

Given Moghbeli's latest comments, he likely was spot on in his predictions.

More on the ISS: Space Station Turns 25, Just in Time to Die


'Dark force' theory could solve 2 open cosmic mysteries
Robert Lea
Fri, December 8, 2023

An illustration of a bright galaxy surrounded by a blueish halo. 

A new theory that suggests dark matter is made up of particles that strongly interact with each other via a so-called "dark force." If true, this may finally explain the extreme densities we see in dark matter haloes surrounding galaxies.

The existence of particles called self-interacting dark matter (SIDM) acts as an alternative to cold dark matter theories which suggest the elusive stuff is made up of massive, slow-moving (and thus cold), weakly interacting particles that don’t collide. The problem with those cold dark matter models is that they struggle to explain two puzzles surrounding what are known as dark matter haloes.

"The first is a high-density dark matter halo in a massive elliptical galaxy. The halo was detected through observations of strong gravitational lensing, and its density is so high that it is extremely unlikely in the prevailing cold dark matter theory," Hai-Bo Yu, team leader and a professor of physics and astronomy at the University of California, Riverside, said in a statement.

"The second," he continued, "is that dark matter halos of ultra-diffuse galaxies have extremely low densities, and they are difficult to explain by the cold dark matter theory."

Related: Dark matter may be hiding in the Large Hadron Collider’s particle jets
The haloes

Dark matter presents a major conundrum for scientists because, despite making up around 85% of the matter in the cosmos, it does not interact with light and therefore remains virtually invisible to us. This tells researchers that dark matter can't just be unseen conglomerations of matter made up of electrons, protons and neutrons — so-called baryonic matter that comprises stars, planets, our bodies and pretty much everything we see around us on a day-to-day basis. No, dark matter has to be made of something else.

The only way that researchers can infer the existence of dark matter at all, in fact, is because it has mass and thus interacts with gravity. This effect can be "felt" by baryonic matter we can indeed see and by light, which astronomers are definitely able to observe.

More specifically, when light travels past these dark matter-wrapped galaxies from background sources, the substance's influence on the fabric of space diverts the light's path and, in turn, makes the background sources appear "shifted" to new locations in space.

This effect, dubbed gravitational lensing, is what originally allowed scientists to determine that most, if not all, galaxies are surrounded by haloes of dark matter in the first place. And these haloes are believed to extend far beyond the limits of those galaxies' visible matter objects like stars, gas and dust. Gravitational lensing has also allowed astronomers to measure the density of dark matter haloes. Denser haloes are responsible for stronger lensing than less dense haloes around ultra-diffuse galaxies — low-brightness galaxies with scattered gas and stars. However, researchers have struggled to explain the extremes of dark matter halo densities.
Enter, artificial intelligence

To tackle this puzzle, Yu and colleagues, including the University of Southern California postdoctoral researchers Ethan Nadler and Daneng Yang, constructed high-resolution simulations of cosmic structures that are based on actual astronomical observations.

They factored into these simulations strong dark matter self-interactions on mass scales relating to strong lensing haloes and ultra-diffuse galaxies.

"These self-interactions lead to heat transfer in the halo, which diversifies the halo density in the central regions of galaxies," Nadler explained. "In other words, some halos have higher central densities, and others have lower central densities, compared to their cold dark matter counterparts, with details depending on the cosmic evolution history and environment of individual halos."

The team concluded that SIDM interacting through a "dark force," just as baryonic particles interact through the force of electromagnetism and via the strong and weak nuclear forces, could offer a solution that cold dark matter theories don’t deliver.

"Cold dark matter is challenged to explain these puzzles. SIDM is arguably the compelling candidate to reconcile the two opposite extremes," Yang added. "Now there is an intriguing possibility that dark matter may be more complex and vibrant than we expected."

Related Stories:

— We still don't know what dark matter is, but here's what it's not

— Astronomers weigh ancient galaxies' dark matter haloes for 1st time

— Could a 'supervoid' solve an unrelenting debate over the universe's expansion rate?

The team thinks their research also provides an example of the analytical power of uniting real observations of the universe, which grow in detail with each new generation of telescope, with the burgeoning power of artificial intelligence.

"We hope our work encourages more studies in this promising research area," Yu said. "It will be a particularly timely development given the expected influx of data in the near future from astronomical observatories, including the James Webb Space Telescope and upcoming Rubin Observatory."

The team’s research was published in November in The Astrophysical Journal Letters.

New dark matter theory has a terrifying explanation for the universe’s expansion
Just trying to keep the lights on




STORY BY
Tristan Greene

A new theory published in the APS physicsjournal seeks to explain the origin and proliferation of dark matter through the introduction of a simple concept: what if dark matter can turn regular matter into dark matter?

Up front: Physicists have long suspected that dark matter has either existed for as long as the universe or that it was created as a byproduct of the Big Bang event. We’re not quite sure, but that’s because nobody’s ever directly observed dark matter.

We assume it exists because we can see objects and events we can observe reacting to something mysterious. Scientists who believe in the dark matter theory (arguably, most physicists) tend to agree that the universe is probably mostly dark matter.

But there’s a problem. There seems to be far too much dark matter in the universe. Residual dark matter from the Big Bang or whatever doesn’t quite explain how the stuff seems to be everywhere.

Background: The team’s paper proposes some high-level mathematics to cope with dark matter at the universal scale, but trying to determine the physics of something you can’t observe is a tough nut to crack.

However, you don’t have to be an astrophysicist to understand that a universe where dark matter could turn regular matter into dark matter could be a short-lived one.

As anyone who has ever played Go knows, when two players are given a completely equal starting point, the one with the superior strategy wins.

But, a game of Go where only one player can flip the other’s pieces is a guaranteed victory for the player with advantage.

In other words: A universe where dark matter worked under the same rules as Romero zombies do (zombies can turn humans into zombies, but humans can’t turn zombies into humans) would be one that quickly filled with dark matter.

But there’s a catch! Our universe is expanding. The scientists explain how matter can persist in a universe where dark matter has all the power by pointing out that dark matter can’t convert regular matter if the cosmos is stretching away from it.

Quick take: The theory sounds pretty cool. I especially like the part where the universe is basically like Sandra Bullock in the movie Speed; if it stops expanding at a specific rate we’ll all be consumed by perpetual darkness.

But I do have to wonder: if the universe is expanding away from dark matter, what’s filling in the gaps?

Read the whole fascinating paper here on APS Physics.

Dark Matter Halos of Newly Discovered Ultra-Diffuse Galaxies Are “Very Odd”

By UNIVERSITY OF CALIFORNIA - RIVERSIDE OCTOBER 17, 2022

The invisible halo that surrounds and permeates a galaxy or galaxy cluster is known as a dark matter halo

A University of California, Riverside physicist explains.

In a study co-led by physicists at the University of California, Riverside and the University of California, Irvine, it was discovered that the dark matter halos of ultra-diffuse galaxies are very odd, raising questions about the current understanding of galaxy formation and the universe’s structure.

The name “ultra-diffuse galaxies” refers to their exceedingly low luminosity. When compared to “normal” galaxies of comparable mass, the distribution of baryons — gas and stars — in ultra-diffuse galaxies is significantly more spread out.

Hai-Bo Yu is a theoretical physicist at UC Riverside. Credit: Samantha Tieu

In the following Q&A, Hai-Bo Yu, an associate professor of physics and astronomy at UCR, discusses the findings he and UCI’s Manoj Kaplinghat, a long-term colleague of Yu’s, published in The Astrophysical Journal regarding newly found ultra-diffuse galaxies and their dark matter halos.

Demao Kong of Tufts University, as well as Filippo Fraternali and Pavel E. Mancera Pia of the University of Groningen in the Netherlands, collaborated with Yu and Kaplinghat on the study. Kong, the first author, will join UCR this fall.

Q. What is a dark matter halo?

A dark matter halo is the halo of invisible matter that permeates and surrounds a galaxy or a cluster of galaxies. Although dark matter has never been detected in laboratories, physicists are confident dark matter, which makes up 85% of the universe’s matter, exists.

Q. You’ve found dark matter halos of the ultra-diffuse galaxies are very odd. What is odd about them and what are you comparing them to?

The ultra-diffuse galaxies we studied are much less massive compared to, say, the Milky Way. They contain a lot of gas, however, and they have much higher gas mass than total stellar mass, which is opposite to what we see in the Milky Way. The ultra-diffuse galaxies also have large sizes.

The distribution of dark matter in these galaxies can be inferred from the motion of gas particles. What really surprises us is that the presence of baryonic matter itself, predominantly in the form of gas, is nearly sufficient to explain the measured velocity of gas particles and leaves little room for dark matter in the inner regions, where most of the stars and gas are located.

This is very surprising because, in the case of normal galaxies, whose masses are similar to those of ultra-diffuse galaxies, it’s the opposite: dark matter dominates over baryonic matter. To accommodate this result, we conclude that these dark matter halos must have much lower “concentrations.” That is, they contain much less mass in their inner regions, compared to those of normal galaxies. In this sense, dark matter halos of the ultra-diffuse galaxies are “odd.”

At first glance, one would expect that such low-concentration halos are so rare that the ultra-diffuse galaxies would not even exist. After looking into the data from state-of-the-art numerical simulations of cosmic structure formation, however, we found the population of low-concentration halos is higher than the expectation.

Q. What was involved in doing the study?

This is a collaborative work. Filippo Fraternali and his student Pavel E. Mancera Piña are experts on the gas dynamics of galaxies. They discovered that ultra-diffuse galaxies rotate more slowly than normal galaxies with similar masses. We worked together to interpret measurement data of the gas motion of these galaxies and infer their dark matter distribution. Furthermore, we analyzed data from simulations of cosmic structure formation and identified dark matter halos that have similar properties as those inferred from the ultra-diffuse galaxies.

Q. Your findings raise questions about our understanding of galaxy formation/structure formation of the universe. How?

We have many questions regarding the formation and evolution of these newly discovered galaxies. For example, ultra-diffuse galaxies contain a lot of gas and we do not know how this gas is retained during galaxy formation. Further, our results indicate that these galaxies may be younger than normal galaxies. The formation of the ultra-diffuse galaxies is not well understood, and more work is needed.

Q. What makes ultra-diffuse galaxies so interesting?

These are amazing objects to study because of their surprising properties, as discussed in our work. The newly discovered ultra-diffuse galaxies provide a new window for further testing our understanding of galaxy formation, probably even the nature of dark matter.

Reference: “The Odd Dark Matter Halos of Isolated Gas-rich Ultradiffuse Galaxies” by Demao Kong, Manoj Kaplinghat, Hai-Bo Yu, Filippo Fraternali and Pavel E. Mancera Piña, 12 September 2022, The Astrophysical Journal.
DOI: 10.3847/1538-4357/ac8875

The study was funded by the National Science Foundation, the United States Department of Energy, the John Templeton Foundation, and NASA.

Black holes may be swallowing invisible matter that slows the movement of stars


Robert Lea
Fri, March 24, 2023 

An illustration of a supermassive black hole ringed with a fiery orange accretion disk ending in a thick ring of black dust

For the first time, scientists may have discovered indirect evidence that large amounts of invisible dark matter surround black holes. The discovery, if confirmed, could represent a major breakthrough in dark matter research.

Dark matter makes up around 85% of all matter in the universe, but it is almost completely invisible to astronomers. This is because, unlike the matter that comprises stars, planets and everything else around us, dark matter doesn't interact with light and can't be seen.

Fortunately, dark matter does interact gravitationally, enabling researchers to infer the presence of dark matter by looking at its gravitational effects on ordinary matter "proxies." In the new research, a team of scientists from The Education University of Hong Kong (EdUHK) used stars orbiting black holes in binary systems as these proxies.

Related: What's the biggest black hole in the universe?

The team watched as the orbits of two stars decayed, or slightly slowed, by about 1 millisecond per year while moving around their companion black holes, designated A0620–00 and XTE J1118+480. The team concluded that the slow-down was the result of dark matter surrounding the black holes which generated significant friction and a drag on the stars as they whipped around their high-mass partners.

Using computer simulations of the black hole systems, the team applied a widely held model in cosmology called the dark matter dynamical friction model, which predicts a specific loss of momentum on objects interacting gravitationally with dark matter. The simulations revealed that the observed rates of orbital decay matched the predictions of the friction model. The observed rate of orbital decay is around 50 times greater than the theoretical estimation of about 0.02 milliseconds of orbital decay per year for binary systems lacking dark matter.

"This is the first-ever study to apply the 'dynamical friction model' in an effort to validate and prove the existence of dark matter surrounding black holes," Chan Man Ho, the team leader and an associate professor in the Department of Science and Environmental Studies at EdUHK, said in a statement.

The team's results, published Jan. 30 in The Astrophysical Journal Letters, help to confirm a long-held theory in cosmology that black holes can swallow dark matter that comes close enough to them. This results in the dark matter being redistributed around the black holes, creating a "density spike" in their immediate vicinity that can subtly influence the orbit of surrounding objects.

Related stories

—8 ways we know that black holes really do exist

—9 ideas about black holes that will blow your mind

—The 10 most massive black hole findings from 2022

Chan explained that previous attempts to study dark matter around black holes have relied on the emission of high-energy light in the form of gamma rays, or ripples in space known as gravitational waves. These emissions result from the collision and resulting merger of black holes – a rare event in the universe that can leave astronomers waiting a long time for sufficient data.

This research gives scientists a new way to study dark matter distributed around black holes that may help them to be more proactive in their search. The EdUHK team intends to hunt for similar black hole binary systems to study in the future.

"The study provides an important new direction for future dark matter research," Chan said. "In the Milky Way Galaxy alone, there are at least 18 binary systems akin to our research subjects, which can provide rich information to help unravel the mystery of dark matter."

 

Mysterious results in an experiment may be due to dark energy

Shane McGlaun - Sep 16, 2021, 

One of the most mysterious subjects that scientists around the world are studying is called dark energy. Scientists believe dark energy is the mysterious force that leads to acceleration in the universe. A team of researchers from the University of Cambridge has published a study that suggests unexplained results obtained from an experiment conducted in Italy called XENON1T could have been caused by dark energy.

Interestingly, the experiment was designed to detect dark matter, but Cambridge scientists believe dark energy could account for the mysterious and unexplained results from the experiment. In the study, physical models were constructed in an attempt to explain the experiment results. Study researchers believe the experiment results could have been caused by dark energy particles in a region of the sun dominated by strong magnetic fields.

Unfortunately, additional experiments will be required to confirm their theory. Nevertheless, scientists are excited at the possibility of the discovery of dark energy. Currently, estimates predict that everything we can see with our eyes in the universe accounts for less than five percent of what’s there. Most of the material in the universe is dark, and theories suggest 27 percent of the entire universe is dark matter.

Dark matter is described as a force that holds galaxies and the cosmos itself together. Scientists also believe that 68 percent of the universe is made up of dark energy causing the universe to expand and accelerate. Since both dark matter and dark energy are invisible, little is known about them.

The presence of dark matter was first theorized in the 1920s, but dark energy wasn’t discovered until 1998. Scientists say that while the experiment was intended to detect dark matter, detecting dark energy is even more difficult. The study comes after the XEON1T experiment discovered an unexpected signal about a year ago that was higher than the expected background. Researchers on this study decided to explore a model where the unexpected signal was attributed to dark energy rather than dark matter. Scientists admit they are still far from understanding dark energy, and additional experiments are needed.

Have we detected dark energy? Scientists say it's a possibility

by University of Cambridge

Credit: CC0 Public Domain

A new study, led by researchers at the University of Cambridge and reported in the journal Physical Review D, suggests that some unexplained results from the XENON1T experiment in Italy may have been caused by dark energy, and not the dark matter the experiment was designed to detect.

They constructed a physical model to help explain the results, which may have originated from dark energy particles produced in a region of the Sun with strong magnetic fields, although future experiments will be required to confirm this explanation. The researchers say their study could be an important step toward the direct detection of dark energy.

Everything our eyes can see in the skies and in our everyday world—from tiny moons to massive galaxies, from ants to blue whales—makes up less than five percent of the universe. The rest is dark. About 27% is dark matter—the invisible force holding galaxies and the cosmic web together—while 68% is dark energy, which causes the universe to expand at an accelerated rate.

"Despite both components being invisible, we know a lot more about dark matter, since its existence was suggested as early as the 1920s, while dark energy wasn't discovered until 1998," said Dr. Sunny Vagnozzi from Cambridge's Kavli Institute for Cosmology, the paper's first author. "Large-scale experiments like XENON1T have been designed to directly detect dark matter, by searching for signs of dark matter 'hitting' ordinary matter, but dark energy is even more elusive."

To detect dark energy, scientists generally look for gravitational interactions: the way gravity pulls objects around. And on the largest scales, the gravitational effect of dark energy is repulsive, pulling things away from each other and making the Universe's expansion accelerate.

About a year ago, the XENON1T experiment reported an unexpected signal, or excess, over the expected background. "These sorts of excesses are often flukes, but once in a while they can also lead to fundamental discoveries," said Dr. Luca Visinelli, a researcher at Frascati National Laboratories in Italy, a co-author of the study. "We explored a model in which this signal could be attributable to dark energy, rather than the dark matter the experiment was originally devised to detect."

At the time, the most popular explanation for the excess were axions—hypothetical, extremely light particles—produced in the Sun. However, this explanation does not stand up to observations, since the amount of axions that would be required to explain the XENON1T signal would drastically alter the evolution of stars much heavier than the Sun, in conflict with what we observe.

We are far from fully understanding what dark energy is, but most physical models for dark energy would lead to the existence of a so-called fifth force. There are four fundamental forces in the universe, and anything that can't be explained by one of these forces is sometimes referred to as the result of an unknown fifth force.

However, we know that Einstein's theory of gravity works extremely well in the local universe. Therefore, any fifth force associated to dark energy is unwanted and must be 'hidden' or 'screened' when it comes to small scales, and can only operate on the largest scales where Einstein's theory of gravity fails to explain the acceleration of the Universe. To hide the fifth force, many models for dark energy are equipped with so-called screening mechanisms, which dynamically hide the fifth force.

Vagnozzi and his co-authors constructed a physical model, which used a type of screening mechanism known as chameleon screening, to show that dark energy particles produced in the Sun's strong magnetic fields could explain the XENON1T excess.

"Our chameleon screening shuts down the production of dark energy particles in very dense objects, avoiding the problems faced by solar axions," said Vagnozzi. "It also allows us to decouple what happens in the local very dense Universe from what happens on the largest scales, where the density is extremely low."

The researchers used their model to show what would happen in the detector if the dark energy was produced in a particular region of the Sun, called the tachocline, where the magnetic fields are particularly strong.

"It was really surprising that this excess could in principle have been caused by dark energy rather than dark matter," said Vagnozzi. "When things click together like that, it's really special."

Their calculations suggest that experiments like XENON1T, which are designed to detect dark matter, could also be used to detect dark energy. However, the original excess still needs to be convincingly confirmed. "We first need to know that this wasn't simply a fluke," said Visinelli. "If XENON1T actually saw something, you'd expect to see a similar excess again in future experiments, but this time with a much stronger signal."

If the excess was the result of dark energy, upcoming upgrades to the XENON1T experiment, as well as experiments pursuing similar goals such as LUX-Zeplin and PandaX-xT, mean that it could be possible to directly detect dark energy within the next decade.

New study sows doubt about the composition of 70 percent of our universe

More information: Sunny Vagnozzi et al, Direct detection of dark energy: The XENON1T excess and future prospects, Physical Review D (2021). DOI: 10.1103/PhysRevD.104.063023

Journal information: Physical Review D 

Provided by University of Cambridge 

Dark Energy Could Be Responsible for Mysterious Experiment Signals, Researchers Say

What if a bunch of liquid xenon under the Apennine Mountains found 68% of the universe?

By
Isaac Schultz
Friday 3:03PM

The XENON1T Time Projection Chamber TPC in a clean room.

Photo: XENON1T / Purdue University

A team of physicists at the University of Cambridge suspects that dark energy may have muddled results from the XENON1T experiment, a series of underground vats of xenon that are being used to search for dark matter.


Dark matter and dark energy are two of the most discussed quandaries of contemporary physics. The two darks are placeholder names for mysterious somethings that seem to be affecting the behavior of the universe and the stuff in it. Dark matter refers to the seemingly invisible mass that only makes itself known through its gravitational effects. Dark energy refers to the as-yet unexplained reason for the universe’s accelerating expansion. Dark matter is thought to make up about 27% of the universe, while dark energy is 68%, according to NASA.

Physicists have some ideas to explain dark matter: axions, WIMPs, SIMPs, and primordial black holes, to name a few. But dark energy is a lot more enigmatic, and now a group of researchers working on XENON1T data says an unexpected excess of activity could be due to that unknown force, rather than any dark matter candidate. The team’s research was published this week in Physical Review D.

The XENON1T experiment, buried below Italy’s Apennine Mountains, is set up to be as far away from any noise as possible. It consists of vats of liquid xenon that will light up if interacted with by a passing particle. As previously reported by Gizmodo, in June 2020 the XENON1T team reported that the project was seeing more interactions than it ought to be under the Standard Model of physics, meaning that it could be detecting theorized subatomic particles like axions—or something could be screwy with the experiment.

“These sorts of excesses are often flukes, but once in a while they can also lead to fundamental discoveries,” said Luca Visinelli, a researcher at Frascati National Laboratories in Italy and a co-author of the study, in a University of Cambridge release. “We explored a model in which this signal could be attributable to dark energy, rather than the dark matter the experiment was originally devised to detect.”

“We first need to know that this wasn’t simply a fluke,” Visinelli added. “If XENON1T actually saw something, you’d expect to see a similar excess again in future experiments, but this time with a much stronger signal.”


Despite constituting so much of the universe, dark energy has not yet been identified. Many models suggest that there may be some fifth force besides the known four known fundamental forces in the universe, one that is hidden until you get to some of the largest-scale phenomena, like the universe’s ever-faster expansion.

Axions shooting out of the Sun seemed a possible explanation for the excess signal, but there were holes in that idea, as it would require a re-think of what we know about stars. “Even our Sun would not agree with the best theoretical models and experiments as well as it does now,” one researcher told Gizmodo last year.

Part of the problem with looking for dark energy are “chameleon particles” (also known as solar axions or solar chameleons), so-called for their theorized ability to vary in mass based on the amount of matter around them. That would make the particles’ mass larger when passing through a dense object like Earth and would make their force on surrounding masses smaller, as New Atlas explained in 2019. The recent research team built a model that uses chameleon screening to probe how dark energy behaves on scales well beyond that of the dense local universe.

“Our chameleon screening shuts down the production of dark energy particles in very dense objects, avoiding the problems faced by solar axions,” said lead author Sunny Vagnozzi, a cosmologist at Cambridge’s Kavli Institute for Cosmology, in a university release. “It also allows us to decouple what happens in the local very dense Universe from what happens on the largest scales, where the density is extremely low.”

The model allowed the team to understand how XENON1T would behave if the dark energy were produced in a magnetically strong region of the Sun. Their calculations indicated that dark energy could be detected with XENON1T.

Since the excess was first discovered, ​​the XENON1T team “tried in any way to destroy it,” as one researcher told The New York Times. The signal’s obstinacy is as perplexing as it is thrilling.

“The authors propose an exciting and interesting possibility to expand the scope of the dark matter detection experiments towards the direct detection of dark energy,” Zara Bagdasarian, a physicist at UC Berkeley who was unaffiliated with the recent paper, told Gizmodo in an email. “The case study of XENON1T excess is definitely not conclusive, and we have to wait for more data from more experiments to test the validity of the solar chameleons idea.”

The next generation of XENON1T, called XENONnT, is slated to have its first experimental runs later this year. Upgrades to the experiment will hopefully seal out any noise and help physicists home in on what exactly is messing with the subterranean detector.

  

SEE

LA REVUE GAUCHE - Left Comment: Search results for ETHER (plawiuk.blogspot.com)

New look at ‘Einstein rings’ around distant galaxies just got us closer to solving the dark matter debate\
The Conversation
April 25, 2023

ESA / Hubble & NASA

Physicists believe most of the matter in the universe is made up of an invisible substance that we only know about by its indirect effects on the stars and galaxies we can see.

We’re not crazy! Without this “dark matter”, the universe as we see it would make no sense.

But the nature of dark matter is a longstanding puzzle. However, a new study by Alfred Amruth at the University of Hong Kong and colleagues, published in Nature Astronomy, uses the gravitational bending of light to bring us a step closer to understanding.

Invisible but omnipresent

The reason we think dark matter exists is that we can see the effects of its gravity in the behavior of galaxies. Specifically, dark matter seems to make up about 85% of the universe’s mass, and most of the distant galaxies we can see appear to be surrounded by a halo of the mystery substance.

But it’s called dark matter because it doesn’t give off light, or absorb or reflect it, which makes it incredibly difficult to detect.

So what is this stuff? We think it must be some kind of unknown fundamental particle, but beyond that we’re not sure. All attempts to detect dark matter particles in laboratory experiments so far have failed, and physicists have been debating its nature for decades.

Scientists have proposed two leading hypothetical candidates for dark matter: relatively heavy characters called weakly interacting massive particles (or WIMPs), and extremely lightweight particles called axions. In theory, WIMPs would behave like discrete particles, while axions would behave a lot more like waves due to quantum interference.

It has been difficult to distinguish between these two possibilities – but now light bent around distant galaxies has offered a clue.

Gravitational lensing and Einstein rings

When light traveling through the universe passes a massive object like a galaxy, its path is bent because – according to Albert Einstein’s theory of general relativity – the gravity of the massive object distorts space and time around itself.

As a result, sometimes when we look at a distant galaxy we can see distorted images of other galaxies behind it. And if things line up perfectly, the light from the background galaxy will be smeared out into a circle around the closer galaxy.

This distortion of light is called “gravitational lensing”, and the circles it can create are called “Einstein rings”.


By studying how the rings or other lensed images are distorted, astronomers can learn about the properties of the dark matter halo surrounding the closer galaxy.

Axions vs WIMPs

And that’s exactly what Amruth and his team have done in their new study. They looked at several systems where multiple copies of the same background object were visible around the foreground lensing galaxy, with a special focus on one called HS 0810+2554.


Multiple images of a background image created by gravitational lensing can be seen in the system HS 0810+2554. Hubble Space Telescope / NASA / ESA

Using detailed modelling, they worked out how the images would be distorted if dark matter were made of WIMPs vs how they would if dark matter were made of axions. The WIMP model didn’t look much like the real thing, but the axion model accurately reproduced all features of the system.

The result suggests axions are a more probable candidate for dark matter, and their ability to explain lensing anomalies and other astrophysical observations has scientists buzzing with excitement.
Particles and galaxies

The new research builds on previous studies that have also pointed towards axions as the more likely form of dark matter. For example, one study looked at the effects of axion dark matter on the cosmic microwave background, while another examined the behavior of dark matter in dwarf galaxies.

Although this research won’t yet end the scientific debate over the nature of dark matter, it does open new avenues for testing and experiment. For example, future gravitational lensing observations could be used to probe the wave-like nature of axions and potentially measure their mass.

A better understanding of dark matter will have implications for what we know about particle physics and the early universe. It could also help us to understand better how galaxies form and change over time.

Rossana Ruggeri, Research Fellow in Cosmology, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

BEFORE DARK MATTER OR DARK ENERGY THERE WAS ETHER  

SPACE

The hottest catalog of the year: the most comprehensive list of slow-building solar flares yet

Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - SAN DIEGO

 

IMAGE: 

THIS IMAGE, TAKEN ON AUG. 5, 2023, SHOWS A BLEND OF EXTREME ULTRAVIOLET LIGHT THAT HIGHLIGHTS THE INTENSELY HOT MATERIAL IN FLARES AND WHICH IS COLORIZED IN RED AND ORANGE.

view more 

CREDIT: (CR: NASA/GSFC/SDO)

Solar flares occur when magnetic energy builds up in the Sun’s atmosphere and is released as electromagnetic radiation. Lasting anywhere from a few minutes to a few hours, flares usually reach temperatures around 10 million degrees Kelvin. Because of their intense electromagnetic energy, solar flares can cause disruptions in radio communications, Earth-orbiting satellites and even result in blackouts.

Although flares have been classified based on the amount of energy they emit at their peak, there has not been significant study into differentiating flares based on the speed of energy build-up since slow-building flares were first discovered in the 1980s. In a new paper in Solar Physics, a team, led by UC San Diego astrophysics graduate student Aravind Bharathi Valluvan, has shown that there is a significant amount of slower-type flares worthy of further investigation.

The width-to-decay ratio of a flare is the time it takes to reach maximum intensity to the time it takes to dissipate its energy. Most commonly, flares spend more time dissipating than rising. In a 5-minute flare, it may take 1 minute to rise and 4 minutes to dissipate for a ratio of 1:4. In slow-building flares, that ratio may be 1:1, with 2.5 minutes to rise and 2.5 minutes to dissipate.

Valluvan was a student at the Indian Institute of Technology Bombay (IITB) when this work was conducted. Exploiting the increased capabilities of the Chandrayaan-2 solar orbiter, IITB researchers used the first three years of observed data to catalog nearly 1400 slow-rising flares — a dramatic increase over the roughly 100 that had been previously observed over the past four decades. 

It was thought that solar flares were like the snap of a whip — quickly injecting energy before slowly dissipating. Now seeing slow-building flares in such high quantities may change that thinking.

“There is thrilling work to be done here,” stated Valluvan who now works in UC San Diego Professor of Astronomy and Astrophysics Steven Boggs’ group. “We’ve identified two different types of flares, but there may be more. And where do the processes differ? What makes them rise and fall at different rates? This is something we need to understand.”

---

JOURNAL

Solar Physics

DOI

10.1007/s11207-023-02244-0 

METHOD OF RESEARCH

Data/statistical analysis

ARTICLE TITLE

Solar Flare Catalogue from 3 Years of Chandrayaan-2 XSM Observations

Lopsided galaxies shed light on the speed of dark matter

Peer-Reviewed Publication

ESTONIAN RESEARCH COUNCIL

 

IMAGE: 

DYNAMICAL FRICTION. THE PANELS DEPICT SPARSE AREAS OF THE UNIVERSE WITH DARK COLOUR AND DENSE AREAS WITH LIGHT COLOUR. THE UPPER PANELS SHOW THE DENSITY AROUND A GALAXY IF THE GALAXY'S GRAVITY BENDS (LEFT) OR DOES NOT BEND (RIGHT) THE TRAJECTORIES OF DARK MATTER PARTICLES. THE LOWER PANEL SHOWS THE DIFFERENCE BETWEEN THEM, OR HOW THE GALAXY AFFECTS THE DISTRIBUTION OF DARK MATTER. THE ARROWS REPRESENT THE ACCELERATION CAUSED BY THE OVERDENSITY BEHIND THE GALAXY, FROM WHICH THE FRICTION ON THE CENTRE OF THE GALAXY IS DEDUCTED. SINCE THE ARROWS HAVE DIFFERENT DIRECTIONS AND STRENGTHS IN DIFFERENT AREAS, THE TIDAL FORCES ARE ABLE TO CHANGE THE SHAPE OF A GALAXY.

view more 

CREDIT: RAIN KIPPER

So how can the speed of dark matter be measured? The prerequisite is to find a galaxy in the universe that moves relative to dark matter. Since everything in the universe is in motion and there is a great deal of dark matter, it is not difficult to find such galaxies.

Heavy objects, like galaxies, attract all types of matter, whether it is dark matter or visible matter that we encounter on a daily basis. As dark matter moves past a galaxy, the galaxy begins to pull the dark matter particles towards it. However, the change of speed direction of the particles takes time. Before their trajectory curves towards the galaxy, they already manage to pass the galaxy.

Thus, dark matter particles do not enter the galaxy, but instead move behind the galaxy (see video). Behind the galaxy, therefore, the density of matter increases, and this leads to a slowdown of the galaxy – a phenomenon called dynamical friction. The strength of dynamical friction, in turn, depends on how quickly dark matter particles pass the galaxy, that is, how long the galaxy has time to change the trajectory of the dark matter particles. When particles pass slowly, the density of matter increases closer to the galaxy, causing it to slow down more.

The green dot represents a galaxy, and the upper panels show the movement of dark matter particles past the galaxy (if a galaxy exists in the corresponding panel). The lower panels show the shape of all the trajectories, demonstrating that the gravity field of a galaxy affects the particles of matter, creating an overdensity behind the galaxy. Overdensity again slows down the galaxy and distorts its shape.

Let us assume that the galaxy causing the dynamical friction is not tiny, but large. In this case, the overdensity behind it generates friction of different strengths at different points in the galaxy, as seen in Figure 1. The difference in friction makes the shape of the galaxy more lopsided. We experience a similar change in shape on Earth as tidal cycles – high tides and low tides caused by the gravity of the moon.
It is irrelevant how big the dark matter particles eventually turn out to be – their orbit still curves behind the galaxy. The method might not produce accurate results if the particles were comparable in size to the galaxies themselves. However, these dark matter models are already excluded.

Finding the lopsided galaxies themselves is not difficult, because they make up about 30 percent of all galaxies in outer space. Of course, a lot depends on how far to look in the outer parts of a galaxy and what level of lopsidedness deems a galaxy lopsided.

Also, the lopsided shape of a galaxy may not be caused only by dynamical friction. There are a number of other reasons for that. For example, galaxies that were formed after the collision of several galaxies may be asymmetric. In this case, however, we should be able to detect somewhere inside the galaxy the nucleus of another galaxy or a larger stellar halo. Galactic lopsidedness can also be caused by a constant inflow of gas. In such situations, the shape of the galaxy will take a few billion years to recover.

Thus, to measure the velocities of dark matter, we need a lopsided galaxy that is as isolated from other galaxies as possible. In this case, it is more certain that nothing has happened to it other than the passage of dark matter.

In this research, we have figured out how to precisely calculate the forces that affect galaxies in tidal cycles. The next stage is to find galaxies sufficiently lopsided in the universe to study the velocity of dark matter relative to the galaxies.

Cosmology is an important test polygon of theoretical physics. Calculating the speed of dark matter can be important for testing new dark matter models and lifting the veil of secrecy over the nature of dark matter.

Dynamical friction video [VIDEO] |

DOI

10.1051/0004-6361/202347235 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Back to the present: A general treatment for the tidal field from the wake of dynamical friction

Fledgling planets discovered around a newly formed star

Six-exoplanet system offers glimpse into planet formation and evolution

Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - RIVERSIDE

 

IMAGE: 

AN AMUSING RENDITION OF THE TOI-1136 SYSTEM IF EACH BODY IN THE SYSTEM WERE A DUCK OR DUCKLING.

view more 

CREDIT: RAE HOLCOMB/UCI

With an arsenal of advanced technology, scientists have found a multi-planet star system that provides a rare insight into the way planets form and behave around a very young star.

TOI-1136 is a dwarf star in the Milky Way galaxy more than 270 light years from Earth, which is considered nearby, as the Milky Way is 100,000 light years in diameter. There are six confirmed planets orbiting the star, and scientists strongly suspect the presence of a seventh.

“Because few star systems have as many planets as this one does, it’s getting close in size to our own solar system,” said Tara Fetherolf, visiting assistant professor of astrophysics at Cal State San Marcos and co-author of a new paper about the system. “It’s both similar enough and different enough that we can learn a lot.”

Published today in The Astronomical Journal, the paper offers precise measurements of the exoplanets’ masses, details about the shape of their orbits, and characteristics of their atmospheres. Details like these were built upon initial observations of the system from 2019 using data from the Transiting Exoplanet Survey Satellite, or TESS. 

Stephen Kane, UC Riverside planetary astrophysics professor and principal investigator of the TESS Keck Survey, explains how the newly discovered system differs from many other known systems. To begin with, its age sets it apart. At a mere 700 million years old, it’s very young compared to our own solar system, which is 4.5 billion years old. 

“This gives us a look at planets right after they’ve formed, and solar system formation is a hot topic. Any time we find a multi-planet system it gives us more information to inform our theories about how systems come to be and how our system got here,” Fetherolf said. 

Juvenile stars are both difficult and special to work with because they’re so active. Magnetism, sunspots and solar flares are more prevalent and intense during this stage of a star’s development, and the resulting radiation blasts and sculpts planets, affecting their atmospheres.

“Young stars misbehave all the time. They’re very active, just like toddlers. That can make high-precisions measurements difficult,” Kane said. 

All the planets are of a similar age in the system, and formed under similar conditions. “This will help us not only do a one-to-one comparison of how planets change with time, but also how their atmospheres evolved at different distances from the star, which is perhaps the most key thing,” Kane said. 

Because all the planets in this system are relatively close together, the research team was also able to measure something that is hard to gauge in other systems. 

“Normally when we’re looking for planets, we’re looking at the effect the planets have on their star. We watch the star move around and interpret that as the gravitational effects the planets are having on it. Here, we can also see the planets pulling on each other,” Kane said. 

Using the Automated Planet Finder telescope at the Lick Observatory on California’s Mount Hamilton and the High-Resolution Echelle Spectrometer at the W.M. Keck Observatory on Hawaii’s Mauna Kea, the researchers detected slight variations in stellar motion that helped them determine the mass of the planets with unprecedented precision. 

To obtain such exact information on the planets, the team built computer models using hundreds of observed velocity measurements layered over transit data. Corey Beard, lead author of the paper and a UC Irvine Ph.D. candidate in physics, said combining these types of readings yielded more knowledge about the system than ever before.

“It took a lot of trial and error, but we were really happy with our results after developing one of the most complicated planetary system models in exoplanet literature to date,” Beard said. 

Joining UC Irvine and UC Riverside on this study were researchers from Spain’s Astrophysics Institute of the Canary Islands; the California Institute of Technology; Sweden’s Chalmers University of Technology; Maryland’s Johns Hopkins University; Spain’s University of La Laguna; Sweden’s Lund University; Poland’s Nicolaus Copernicus University; New Jersey’s Princeton University; Japan’s Ritsumeikan University; California’s SETI Institute; Maryland’s Space Telescope Science Institute; the University of California, Santa Cruz; the University of California, Berkeley; the University of California, Los Angeles; the University of Hawaii; the University of Chicago; the University of Kansas; Indiana’s University of Notre Dame; Australia’s University of Southern Queensland; and Connecticut’s Yale University. Funding was provided by the W.M. Keck Foundation, NASA and the National Science Foundation.

Signs of life on Earth appeared almost immediately after the formation of our solar system during the Archean period 3.9 billion years ago. Though TOI-1136 is too close to most of its planets to make life likely – the radiation would be too intense – the team hopes that observing this system ultimately answers existential questions about how our planet came to be. 

“Are we rare? I’m increasingly convinced our system is highly unusual in the universe. Finding systems so unlike our own makes it increasingly clear how our solar system fits into the broader context of formation around other stars,” said Kane. 

Artist rendering of the TOI-1136 system and its young star flaring. 

CREDIT

Rae Holcomb/Paul Robertson/UCI

---

JOURNAL

The Astronomical Journal

DOI

10.3847/1538-3881/ad1330 

ARTICLE TITLE

The TESS-Keck Survey XVII: Precise Mass Measurements in a Young, High Multiplicity Transiting Planet System using Radial Velocities and Transit Timing Variations

ARTICLE PUBLICATION DATE

29-Jan-2024