Neptune-like exoplanets can be cloudy or clear

The study of "exoplanets," the sci-fi-sounding name for all planets in the cosmos beyond our own solar system, is a pretty new field. Mainly, exoplanet researchers like those in the ExoLab at the University of Kansas use data from space-borne telescopes such as the Hubble Space Telescope and Webb Space Telescope. Whenever news headlines offer findings of "Earth-like" planets or planets with the potential to support humanity, they're talking about exoplanets within our own Milky Way.

Jonathan Brande, a doctoral candidate in the ExoLab at the University of Kansas, has just published findings in the open-access scientific journal The Astrophysical Journal Letters showing new atmospheric detail in a set of 15 exoplanets similar to Neptune. While none could support humanity, a better understanding of their behavior might help us to understand why we don't have a small Neptune, while most solar systems seem to feature a planet of this class.

"Over the past several years at KU, my focus has been studying the atmospheres of exoplanets through a technique known as transmission spectroscopy," Brande said. "When a planet transits, meaning it moves between our line of sight and the star it orbits, light from the star passes through the planet's atmosphere, getting absorbed by the various gases present. By capturing a spectrum of the star -- passing the light through an instrument called a spectrograph, akin to passing it through a prism -- we observe a rainbow, measuring the brightness of different constituent colors. Varied areas of brightness or dimness in the spectrum reveal the gases absorbing light in the planet's atmosphere."

With this methodology, several years ago Brande published a paper concerning the "warm Neptune" exoplanet TOI-674 b, where he presented observations indicating the presence of water vapor in its atmosphere. These observations were part of a broader program led by Brande's adviser, Ian Crossfield, associate professor of physics & astronomy at KU, to observe atmospheres of Neptune-sized exoplanets.

"We want to comprehend the behaviors of these planets, given that those slightly larger than Earth and smaller than Neptune are the most common in the galaxy," Brande said.

This recent ApJL paper summarizes observations from that program, incorporating data from additional observations to address why some planets appear cloudy while others are clear.

"The goal is to explore the physical explanations behind the distinct appearances of these planets," Brande said.

Brande and his co-authors took special note of regions where exoplanets tend to form clouds or hazes high up in their atmosphere. When such atmospheric aerosols are present, the KU researcher said hazes can block the light filtering through the atmosphere.

"If a planet has a cloud right above the surface with hundreds of kilometers of clear air above it, starlight can easily pass through the clear air and be absorbed only by the specific gases in that part of the atmosphere," Brande said. "However, if the cloud is positioned very high, clouds are generally opaque across the electromagnetic spectrum. While hazes have spectral features, for our work, where we focus on a relatively narrow range with Hubble, they also produce mostly flat spectra."

According to Brande, when these aerosols are present high in the atmosphere, there's no clear path for light to filter through.

"With Hubble, the single gas we're most sensitive to is water vapor," he said. "If we observe water vapor in a planet's atmosphere, that's a good indication that there are no clouds high enough to block its absorption. Conversely, if water vapor is not observed and only a flat spectrum is seen, despite knowing that the planet should have an extended atmosphere, it suggests the likely presence of clouds or hazes at higher altitudes."

Brande led the work of an international team of astronomers on the paper, including Crossfield at KU and collaborators from the Max Planck Institute in Heidelberg, Germany, a cohort led by Laura Kreidberg, and investigators at the University of Texas, Austin, led by Caroline Morley.

Brande and his co-authors approached their analysis differently than previous efforts by focusing on determining the physical parameters of the small-Neptune atmospheres. In contrast, previous analyses often involved fitting a single model spectrum to observations.

"Typically, researchers would take an atmospheric model with pre-computed water content, scale and shift it to match observed planets in their sample," Brande said. "This approach indicates whether the spectrum is clear or cloudy but provides no information about the amount of water vapor or the location of clouds in the atmosphere."

Instead, Brande employed a technique known as "atmospheric retrieval."

"This involved modeling the atmosphere across various planet parameters such as water vapor quantity and cloud location, iterating through hundreds and thousands of simulations to find the best fit configuration," he said. "Our retrievals gave us a best-fit model spectrum for each planet, from which we calculated how cloudy or clear the planet appeared to be. Then, we compared those measured clarities to a separate suite of models by Caroline Morley, which let us see that our results are in line with expectations for similar planets. In examining cloud and haze behavior, our models indicated that clouds were a better fit than hazes. The sedimentation efficiency parameter, reflecting cloud compactness, suggested observed planets had relatively low sedimentation efficiencies, resulting in fluffy clouds. These clouds, made up of particles like water droplets, remained lofted in the atmosphere due to their low settling tendency."

Brande's findings provide insights into the behavior of these planetary atmospheres and caused "substantial interest" when he presented them at a recent meeting of the American Astronomical Society.

Read more at Science Daily

Why are people climate change deniers?

Do climate change deniers bend the facts to avoid having to modify their environmentally harmful behavior? Researchers from the University of Bonn and the Institute of Labor Economics (IZA) ran an online experiment involving 4,000 US adults, and found no evidence to support this idea. The authors of the study were themselves surprised by the results. Whether they are good or bad news for the fight against global heating remains to be seen. The study is being published in the journal Nature Climate Change.

A surprisingly large number of people still downplay the impact of climate change or deny that it is primarily a product of human activity.

But why? One hypothesis is that these misconceptions are rooted in a specific form of self-deception, namely that people simply find it easier to live with their own climate failings if they do not believe that things will actually get all that bad.

"We call this thought process 'motivated reasoning,'" says Professor Florian Zimmermann, an economist at the University of Bonn and Research Director at IZA.

Motivated reasoning helps us to justify our behavior. For instance, someone who flies off on holiday several times a year can give themselves the excuse that the plane would still be taking off without them, or that just one flight will not make any difference, or -- more to the point -- that nobody has proven the existence of human-made climate change anyway.

All these patterns of argument are examples of motivated reasoning.

Bending the facts until it allows us to maintain a positive image of ourselves while maintaining our harmful behavior.

Self-deception to preserve a positive self-image

But what role does this form of self-deception play in how people think about climate change?

Previously, there had been little scientific evidence produced to answer the question.

The latest study has now closed this knowledge gap -- and has thrown up some unexpected results.

Zimmermann and his colleague Lasse Stötzer ran a series of online experiments, using a representative sample of 4,000 US adults.

At the center of the experiments was a donation worth $20. Participants were allocated at random to one of two groups.

The members of the first group were able to split the $20 between two organizations, both of which were committed to combating climate change.

By contrast, those in the second group could decide to keep the $20 for themselves instead of giving it away and would then actually receive the money at the end.

"Anyone keeping hold of the donation needs to justify it to themselves," says Zimmermann, who is also a member of the ECONtribute Cluster of Excellence, the Collaborative Research Center Transregio 224 and the Transdisciplinary Research Area "Individuals & Societies" at the University of Bonn.

"One way to do that is to deny the existence of climate change."

As it happened, nearly half of those in the second group decided to hold on to the money.

The researchers now wanted to know whether these individuals would justify their decision retrospectively by repudiating climate change.

The two groups had been put together at random. Without "motivated reasoning," therefore, they should essentially share a similar attitude to human-made global heating.

If those who kept the money for themselves justified their actions through self-deception, however, then their group should exhibit greater doubt over climate change.

"Yet we didn't see any sign of that effect," Zimmermann reveals.

Climate change denial: a hallmark of one's identity?

This finding was also borne out in two further experiments. "In other words, our study didn't give us any indications that the widespread misconceptions regarding climate change are due to this kind of self-deception," says Zimmermann, summing up his work.

On the face of it, this is good news for policymakers, because the results could mean that it is indeed possible to correct climate change misconceptions, simply by providing comprehensive information.

If people are bending reality, by contrast, then this approach is very much a non-starter.

Zimmermann advises to be cautious, however: "Our data does reveal some indications of a variant of motivated reasoning, specifically that denying the existence of human-made global heating forms part of the political identity of certain groups of people." Put another way, some people may to an extent define themselves by the very fact that they do not believe in climate change.

As far as they are concerned, this way of thinking is an important trait that sets them apart from other political groups, and thus they are likely to simply not care what researchers have to say on the topic.

Read more at Science Daily

Gene-editing offers hope for people with hereditary disorder

A group of patients with a hereditary disorder have had their lives transformed by a single treatment of a breakthrough gene-editing therapy, according to the lead researcher.

The patients from New Zealand, the Netherlands and the UK have hereditary angioedema, a genetic disorder characterised by severe, painful and unpredictable swelling attacks.

These interfere with daily life and can affect airways and prove fatal.

Now researchers from the University of Auckland, Amsterdam University Medical Center and Cambridge University Hospitals have successfully treated more than ten patients with the CRISPR/Cas9 therapy, with interim results just published in a leading journal.

"It looks as if the single-dose treatment will provide a permanent cure for my hereditary angioedema patients' very disabling symptoms," says principal investigator Dr Hilary Longhurst, who is both a clinical immunologist at Auckland Hospital Te Toku Tumai and an honorary associate professor at the University of Auckland.

"Plus, of course, there is huge potential for development of similar CRISPR/Cas9 treatments for other genetic disorders."

Globally, it is estimated one in 50,000 people have hereditary angioedema, however, because it is rare, it is often not correctly diagnosed.

In the phase one study, there were no serious or lasting side-effects from the single infusion, which took place over two to four hours under clinical supervision from late 2021 and onwards.

The investigational therapy, called NTLA-2002, utilises in vivo CRISPR/Cas9 technology to target the KLKB1 gene, which is responsible for producing plasma prekallikrein.

By editing this gene, the therapy reduces the levels of total plasma kallikrein, effectively preventing angioedema (swelling) attacks.

The trial, published in the New England Journal of Medicine, demonstrated dose-dependent reduction in total plasma kallikrein protein with reductions of up to 95 percent achieved.

A mean reduction of 95 percent in angioedema attacks was observed across all patients through to the latest follow-up.

The patients from the initial study will be followed up for a further 15 years to continue to assess long-term safety and efficacy.

A larger and more robust, double-blinded, placebo-controlled phase two trial is under way and a Phase 3 trial is planned to start in the second half of 2024.

Dr Danny Cohn, from the Department of Vascular Medicine at the Amsterdam University Medical Center says these promising results are a step forward for this group of patients.

"We've never been closer to the ultimate treatment goal of normalising hereditary angioedema patients' lives and offering total control of the disease," says Dr Cohn.

Dr Padmalal Gurugama, consultant in clinical immunology and allergy at Cambridge University Hospitals, UK says the gene editing therapy has the potential to significantly improve patients' lives.

"Hereditary angioedema can cause patients severe swellings and intense pain which can be life-threatening as well as restricting normal activities, such as going to work or school.

"Because it is often misdiagnosed, many patients undergo unnecessary treatments and invasive procedures."

The therapy affects only the patient and is not passed onto their children, who still have an even chance of inheriting the disorder.

The studies have been funded by US company Intellia Therapeutics, which chose New Zealand to lead the research as, at that time -- late 2021, it had relatively fewer Covid-19 cases than other countries.

So far, the only approved CRISPR therapy, CASGEVY, is for sickle cell disease and beta thalassemia.

However, CASGEVY is an ex vivo CRISPR therapy, where the cells are taken from the patient and edited outside of the body and then reinfused, whereas NTLA-2002 is an in vivo CRISPR therapy, where the targeted gene editing occurs directly within the body.

Read more at Science Daily

The hottest catalog of the year: Comprehensive list of slow-building solar flares

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.

Read more at Science Daily

Death toll shows extreme air pollution events a growing urban threat

New Curtin University-led research has estimated that 1454 avoidable deaths (one person every five days) occurred in Australian capital cities in the past 20 years because of fine particle air pollution from extreme events such as bushfires and dust storms, wood-heater smoke or industrial accidents.

The study also found that nearly one-third of deaths from extreme air pollution exposure days could be prevented if pollution events were reduced by as little as 5 per cent.

Lead researcher Dr Lucas Hertzog from Curtin's World Health Organisation Collaborating Centre for Climate Change and Health Impact Assessment said the findings highlighted the urgent need for effective strategies to manage air quality, particularly during extreme weather events like bushfires and dust storms, which are becoming more common due to climate change.

"Using data from 2001 to 2020 from air pollution monitoring sites, combined with a range of satellite and land use-related data, we modelled the exposure to exceptional levels of particulate matter air pollution (PM2.5) for each extreme pollution exposure day," Dr Hertzog said.

"Despite relatively low daily PM2.5 levels generally (compared to global averages), Australian cities experience days with extreme pollution levels where PM2.5 concentrations exceed the WHO Air Quality Guideline standard.

"Sydney and Melbourne reported the highest number of deaths attributable to extreme air pollution events, with 541 and 438 deaths respectively, followed by Brisbane and Perth with 171 and 132 deaths."

"Adelaide and Hobart were the cities that showed, across the 20-year period, fewer days exceeding WHO air quality exposure recommendations, with Adelaide recording only five days and Hobart 11 days above the threshold.

"Darwin, despite its relatively low number of deaths due to PM2.5 exposure events, experienced a high number of days exceeding WHO recommendations, ten times more than cities like Melbourne."

Dr Hertzog said the findings show how extreme air pollution events could seriously affect health in urban areas, and understanding this link was crucial, as climate change may increase the frequency and intensity of such pollution events.

"Diseases associated with particulate matter air pollution include asthma and COPD (chronic obstructive pulmonary disease) as well as cardiovascular disorders," Dr Hertzog said.

"Our study's insights can aid in protecting public health by helping to inform policy development and actions to reduce impacts from extreme air pollution events.

"While responding to bushfires and dust storms is an increasingly challenging task, authorities have a crucial role in land use management. They also regulate energy policy and control wood heater regulations. Additional strategies to reduce emissions from industrial accidents or road transport-related smog events could enhance the control of sources of air pollution and improve well-being.

"It is also possible to reduce the burden of mortality by improving public health warnings and increasing community awareness of smoke avoidance behaviours."

Read more at Science Daily

'Genomic time machine' reveals secrets of our DNA

The human genome, an intricate tapestry of genetic information for life, has proven to be a treasure trove of strange features. Among them are segments of DNA that can "jump around" and move within the genome, known as "transposable elements" (TEs).

As they change their position within the genome, TEs can potentially cause mutations and alter the cell's genetic profile, but also are master orchestrators of our genome's organization and expression.

For example, TEs contribute to regulatory elements, transcription factor binding sites, and the creation of chimeric transcripts -- genetic sequences created when segments from two different genes or parts of the genome join together to form a new, hybrid RNA molecule.

Matching their functional importance, TEs have been recognized to account for half of the human DNA.

However, as they move and age, TEs pick up changes that mask their original form.

Over time, TEs "degenerate" and become less recognizable, making it difficult for scientists to identify and track them in our genetic blueprint.

In a new study, researchers in the group of Didier Trono at EPFL have found a way to improve the detection of TEs in the human genome by using reconstructed ancestral genomes from various species, which allowed them to identify previously undetectable degenerate TEs in the human genome.

The study is published in Cell Genomics.

The scientists used a database of reconstructed ancestral genomes from different kinds of species, like a genomic "time machine." By comparing the human genome with the reconstructed ancestral genomes, they could identify TEs in the latter that, over millions of years, have become degenerate (worn out) in humans.

This comparison allowed them to detect ("annotate") TEs that might have been missed in previous studies that used data only from the human genome.

Using this approach, the scientists uncovered a larger number of TEs than previously known, adding significantly to the share of our DNA that is contributed by TEs.

Furthermore, they could demonstrate that these newly unearthed TE sequences played all the same regulatory roles as their more recent, already identified relatives.

Read more at Science Daily

Researchers 3D-print functional human brain tissue

A team of University of Wisconsin-Madison scientists has developed the first 3D-printed brain tissue that can grow and function like typical brain tissue.

It's an achievement with important implications for scientists studying the brain and working on treatments for a broad range of neurological and neurodevelopmental disorders, such as Alzheimer's and Parkinson's disease.

"This could be a hugely powerful model to help us understand how brain cells and parts of the brain communicate in humans," says Su-Chun Zhang, professor of neuroscience and neurology at UW-Madison's Waisman Center.

"It could change the way we look at stem cell biology, neuroscience, and the pathogenesis of many neurological and psychiatric disorders."

Printing methods have limited the success of previous attempts to print brain tissue, according to Zhang and Yuanwei Yan, a scientist in Zhang's lab.

The group behind the new 3D-printing process described their method today in the journal Cell Stem Cell.

Instead of using the traditional 3D-printing approach, stacking layers vertically, the researchers went horizontally.

They situated brain cells, neurons grown from induced pluripotent stem cells, in a softer "bio-ink" gel than previous attempts had employed.

"The tissue still has enough structure to hold together but it is soft enough to allow the neurons to grow into each other and start talking to each other," Zhang says.

The cells are laid next to each other like pencils laid next to each other on a tabletop.

"Our tissue stays relatively thin and this makes it easy for the neurons to get enough oxygen and enough nutrients from the growth media," Yan says.

The results speak for themselves -- which is to say, the cells can speak to each other.

The printed cells reach through the medium to form connections inside each printed layer as well as across layers, forming networks comparable to human brains.

The neurons communicate, send signals, interact with each other through neurotransmitters, and even form proper networks with support cells that were added to the printed tissue.

"We printed the cerebral cortex and the striatum and what we found was quite striking," Zhang says.

"Even when we printed different cells belonging to different parts of the brain, they were still able to talk to each other in a very special and specific way."

The printing technique offers precision -- control over the types and arrangement of cells -- not found in brain organoids, miniature organs used to study brains.

The organoids grow with less organization and control.

"Our lab is very special in that we are able to produce pretty much any type of neurons at any time. Then we can piece them together at almost any time and in whatever way we like," Zhang says.

"Because we can print the tissue by design, we can have a defined system to look at how our human brain network operates. We can look very specifically at how the nerve cells talk to each other under certain conditions because we can print exactly what we want."

That specificity provides flexibility. The printed brain tissue could be used to study signaling between cells in Down syndrome, interactions between healthy tissue and neighboring tissue affected by Alzheimer's, testing new drug candidates, or even watching the brain grow.

"In the past, we have often looked at one thing at a time, which means we often miss some critical components. Our brain operates in networks. We want to print brain tissue this way because cells do not operate by themselves. They talk to each other. This is how our brain works and it has to be studied all together like this to truly understand it," Zhang says.

"Our brain tissue could be used to study almost every major aspect of what many people at the Waisman Center are working on. It can be used to look at the molecular mechanisms underlying brain development, human development, developmental disabilities, neurodegenerative disorders, and more."

The new printing technique should also be accessible to many labs.

It does not require special bio-printing equipment or culturing methods to keep the tissue healthy, and can be studied in depth with microscopes, standard imaging techniques and electrodes already common in the field.

The researchers would like to explore the potential of specialization, though, further improving their bio-ink and refining their equipment to allow for specific orientations of cells within their printed tissue..

"Right now, our printer is a benchtop commercialized one," Yan says.

Read more at Science Daily

Clown anemonefish seem to be counting bars and laying down the law

We often think of fish as carefree swimmers in the ocean, reacting to the world around them without much forethought. However, new research from the Okinawa Institute of Science and Technology (OIST) suggests that our marine cousins may be more cognizant than we credit them for.

By observing how a colony of clown anemonefish (Amphiprion ocellaris) -- the species of the titular character in Finding Nemo -- reacts to intruders in their sea anemone home, OIST researchers have found that the fish recognize different anemonefish species based on the number of white bars on their bodies.

"The frequency and duration of aggressive behaviors in clown anemonefish was highest toward fish with three bars like themselves," explains Dr. Kina Hayashi from the Marine Eco-Evo-Devo Unit at OIST, first author on the paper published in the Journal of Experimental Biology, "while they were lower with fish with one or two bars, and lowest toward those without vertical bars, which suggests that they are able to count the number of bars in order to recognize the species of the intruder."

The clown anemonefish is normally a gracious host, allowing many different species to visit their sea anemone.

However, should a member of their own species, and which is not part of the colony, enter their home, the largest fish of the colony, referred to as the alpha fish, will aggressively bite and chase out the intruder.

To figure out how these fish determine the species of their visitors, Dr. Hayashi and colleagues conducted two sets of experiments with immature clown anemonefish raised in the lab.

In the first set, they placed different species of anemonefish, with different numbers of white bars, in small cases inside a tank with a clown anemonefish colony and observed how often and for how long the fish would aggressively stare at and circle the case.

In the second set, the researchers presented a colony of clown anemonefish with different plastic discs painted with true-to-life anemonefish coloration and measured the level of aggression towards these models.

The clown anemonefish displayed the most aggressive behavior towards the intruders with three bars like themselves.

Fish and plastic models with two bars were attacked slightly less frequently, while the ones with one or zero bars received the least aggressive response.

Previous studies have shown that clown anemonefish react much stronger to models with vertical rather than horizontal bars, suggesting that the amount of white color or the general presence of white bars is not the deciding factor.

Combined with the observation that the plastic discs, which have no species defining traits other than the vertical bars, received the same response as the live fish, lead the researchers to suggest that the fish appear to be counting the number of vertical white bars to inform their level of aggression toward intruders.

The researchers also discovered a strict hierarchy in the clown anemonefish colonies that determines which fish attack the intruder.

In the wild, a colony typically consists of one alpha female, one beta male, and several gamma juveniles.

The social position within the colony is determined by very slight differences in size.

Anemonefish get their third and final stripe when they metamorphize into either a male or female when they grow large enough, which is why the current alpha uses harsh methods to uphold the status quo, including chasing out colony members if they grow too large.

Though the researchers used immature fish that have yet to metamorphize into males or females, they still observed the same size-based hierarchy, with the largest juvenile taking on the role of alpha and leading the charge against the intruder.

Read more at Science Daily

Bright galaxies put dark matter to the test

For the past year and a half, the James Webb Space Telescope has delivered astonishing images of distant galaxies formed not long after the Big Bang, giving scientists their first glimpses of the infant universe. Now, a group of astrophysicists has upped the ante: Find the tiniest, brightest galaxies near the beginning of time itself, or scientists will have to totally rethink their theories about dark matter.

The team, led by UCLA astrophysicists, ran simulations that track the formation of small galaxies after the Big Bang and included, for the first time, previously neglected interactions between gas and dark matter. They found that the galaxies created are very tiny, much brighter, and form more quickly than they do in typical simulations that don''t take these interactions into account, instead revealing much fainter galaxies.

Small galaxies, also called dwarf galaxies, are present throughout the universe, and are often thought to represent the earliest type of galaxy. Small galaxies are thus especially interesting to scientists studying the origins of the universe. But the small galaxies they find don't always match what they think they should find. Those closest to the Milky Way spin quicker or are not as dense as in simulations, indicating that the models might have omitted something, such as these gas-dark matter interactions.

The new research, published in The Astrophysical Journal Letters, improves the simulations by adding dark matter interactions with gas and finds that these faint galaxies may have been much brighter than expected early in the universe's history, when they were just beginning to form. The authors suggest scientists should try to find small galaxies that are much brighter than expected using telescopes like the Webb telescope. If they only find faint ones, then some of their ideas about dark matter might be wrong.

Dark matter is a type of hypothetical matter that does not interact with electromagnetism or light. Thus, it is impossible to observe using optics, electricity or magnetism. But dark matter does interact with gravity, and its presence has been inferred from the gravitational effects it has on ordinary matter -- the stuff that makes up all the observable universe. Even though 84% of the matter in the universe is thought to be made of dark matter, it has never been detected directly.

All galaxies are surrounded by a vast halo of dark matter, and scientists think that dark matter was essential to their formation. The "standard cosmological model" astrophysicists use to understand galaxy formation describes how clumps of dark matter in the very early universe drew in ordinary matter through gravity, causing the formation of stars and creating the galaxies we see today. Because most dark matter particles -- called cold dark matter -- are thought to move much slower than the speed of light, this process of accumulation would have occurred gradually.

But over 13 billion years ago, prior to the formation of the first galaxies, ordinary matter, consisting of hydrogen and helium gas from the Big Bang, and dark matter were moving relative to one another. The gas streamed at supersonic velocities past dense thickets of more slowly moving dark matter that should have pulled it in to form galaxies.

"Indeed, in models that do not take streaming into account, this is exactly what happens," said Claire Williams, a UCLA doctoral student and the paper's first author. "Gas is attracted to the gravitational pull of dark matter, forms clumps and knots so dense that hydrogen fusion can occur, and thus forms stars like our sun."

But Williams and co-authors on the Supersonic Project team, a group of astrophysicists from the United States, Italy and Japan led by UCLA physics and astronomy professor Smadar Naoz, found if they added the streaming effect of different velocities between dark and ordinary matter to the simulations, the gas landed far away from the dark matter and was prevented from forming stars right away. When the accumulated gas fell back into the galaxy millions of years later, a massive burst of star formation occurred all at once. Because these galaxies had many more young, hot, luminous stars than ordinary small galaxies for a time, they shone much brighter.

"While the streaming suppressed star formation in the smallest galaxies, it also boosted star formation in dwarf galaxies, causing them to outshine the non-streaming patches of the universe," Williams said. "We predict that the Webb telescope will be able to find regions of the universe where galaxies will be brighter, heightened by this velocity. The fact that they should be so bright might make it easier for the telescope to discover these small galaxies, which are typically extremely hard to detect only 375 million years after the Big Bang."

Because dark matter is impossible to study directly, searching for bright patches of galaxies in the early universe could offer an effective test for theories about dark matter, which has been fruitless so far.

"The discovery of patches of small, bright galaxies in the early universe would confirm that we are on the right track with the cold dark matter model because only the velocity between two kinds of matter can produce the type of galaxy we're looking for," said Naoz, the Howard and Astrid Preston Professor of Astrophysics. "If dark matter does not behave like standard cold dark matter and the streaming effect isn't present, then these bright dwarf galaxies won't be found and we need to go back to the drawing board."

Read more at Science Daily

Unprecedented ocean heating shows risks of a world 3°C warmer

Record-high ocean temperatures observed in 2023 could become the norm if the world moved into a climate that is 3.0°C warmer than pre-industrial levels, according to a new study.

From March 2023, the North Atlantic began to show extremely warm temperatures far exceeding anything seen in the past 40 years.

As of August 2023, the North Atlantic was about 1.4°C warmer than the 1982-2011 average.

Analysis of climate model projections showed that last year's extreme ocean conditions were similar to what scientists expect to be the average if global warming reaches 3°C of warming.

Currently, global temperatures have risen by about 1.2°C above pre-industrial levels.

New research, published this month in the Bulletin of the American Meteorological Society, examines the causes of the record-breaking ocean temperatures witnessed in 2023.

Dr Till Kuhlbrodt, of the University of Reading, led the study.

He said: "The extraordinary heat in the North Atlantic and missing sea ice in the Southern Ocean in 2023 tell us the oceans are sounding an alarm. We urgently need to understand exactly why parts of the ocean are warming rapidly so we can prepare for more frequent weather disruption across the planet. How often we get hit by more of these extremes hangs on figuring out what's driving the Atlantic and Southern Oceans into uncharted territory."

Climate connection?

The study highlights that Earth's energy imbalance is likely a key driver of extreme ocean temperatures, as the planet is currently absorbing more than 1.9 watts per square meter more solar energy than it radiates back to space as heat.

Across Earth, over a time span of one year, this is equivalent to roughly 300 times the global annual consumption of electric energy.

This imbalance has grown fast over recent decades mainly due to heat-trapping gases from human activity.

This increasing energy surplus is propelling ocean warming, with more than 90% of the excess energy accumulated by Earth being funnelled into the oceans.

Since 2016 the Atlantic Ocean has warmed faster than other ocean basins in the top 100 meters of ocean.

This enhanced Atlantic warming may be linked to record low levels of sea ice in the Southern Ocean, the researchers suggest.

The rapid Atlantic warming has coincided with a sharp decline in sea ice cover surrounding Antarctica.

In 2023, Antarctic winter sea ice extent reached by far the lowest levels since satellite monitoring began in the late 1970s.

The researchers emphasise the need to quantify how much the rapid Atlantic warming is impacting sea ice cover.

Reliably attributing the oceanic and sea ice extremes will ensure climate models can accurately predict future extremes, which will inform mitigation policies and resilience measures across the globe.

Read more at Science Daily