From UC Riverside: “Satellite galaxies of the Milky Way help test dark matter theory”

From UC Riverside

April 15, 2020
Iqbal Pittalwala

UC Riverside physicists demonstrate “self-interacting dark matter” model can be tested using astronomical observations of Draco and Fornax.

Image shows Draco on the left (Hubble Space Telescope) and Fornax (ESO/Digitized Sky Survey 2).

A research team led by physicists at the University of California, Riverside, reports tiny satellite galaxies of the Milky Way can be used to test fundamental properties of “dark matter” — nonluminous material thought to constitute 85% of matter in the universe.

Using sophisticated simulations, the researchers show a theory called self-interacting dark matter, or SIDM, can compellingly explain diverse dark matter distributions in Draco and Fornax, two of the Milky Way’s more than 50 discovered satellite galaxies.

The prevailing dark matter theory, called Cold Dark Matter, or CDM, explains much of the universe, including how structures emerge in it. But a long-standing challenge for CDM has been to explain the diverse dark matter distributions in galaxies.

Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes
Alex Mittelmann, Coldcreation

The researchers, led by UC Riverside’s Hai-Bo Yu and Laura V. Sales, studied the evolution of SIDM “subhalos” in the Milky Way “tidal field” — the gradient in the gravitational field of the Milky Way that a satellite galaxy feels in the form of a tidal force. Subhalos are dark matter clumps that host the satellite galaxies.

“We found SIDM can produce diverse dark matter distributions in the halos of Draco and Fornax, in agreement with observations,” said Yu, an associate professor of physics and astronomy and a theoretical physicist with expertise in particle properties of dark matter. “In SIDM, the interaction between the subhalos and the Milky Way’s tides leads to more diverse dark matter distributions in the inner regions of subhalos, compared to their CDM counterparts.”

Draco and Fornax have opposite extremes in their inner dark matter contents. Draco has the highest dark matter density among the nine bright Milky Way satellite galaxies; Fornax has the lowest. Using advanced astronomical measurements, astrophysicists recently reconstructed their orbital trajectories in the Milky Way’s tidal field.

“Our challenge was to understand the origin of Draco and Fornax’s diverse dark matter distributions in light of these newly measured orbital trajectories,” Yu said. “We found SIDM can provide an explanation after taking into both tidal effects and dark matter self-interactions.”

Study results appear in Physical Review Letters.

Dark matter’s nature remains largely unknown. Unlike normal matter, it does not absorb, reflect, or emit light, making it difficult to detect. Identifying the nature of dark matter is a central task in particle physics and astrophysics.

In CDM, dark matter particles are assumed to be collisionless, and every galaxy sits within a dark matter halo that forms the gravitational scaffolding holding it together. In SIDM, dark matter is proposed to self-interact through a new dark force. Dark matter particles are assumed to strongly collide with one another in the inner halo, close to the galaxy’s center — a process called dark matter self-interaction.

“Our work shows satellite galaxies of the Milky Way may provide important tests of different dark matter theories,” said Sales, an assistant professor of physics and astronomy and an astrophysicist with expertise in numerical simulations of galaxy formation. “We show the interplay between dark matter self-interactions and tidal interactions can produce novel signatures in SIDM that are not expected in the prevailing CDM theory.”

In their work, the researchers mainly used numerical simulations, called “N-body simulations,” and obtained valuable intuition through analytical modeling before running their simulations.

“Our simulations reveal novel dynamics when an SIDM subhalo evolves in the tidal field,” said Omid Sameie, a former UCR graduate student who worked with Yu and Sales and is now a postdoctoral researcher at the University of Texas at Austin working on numerical simulations of galaxy formation. “It was thought observations of Draco were inconsistent with SIDM predictions. But we found a subhalo in SIDM can produce a high dark matter density to explain Draco.”

Sales explained SIDM predicts a unique phenomenon named “core collapse.” In certain circumstances, the inner part of the halo collapses under the influence of gravity and produces a high density. This is contrary to the usual expectation that dark matter self-interactions lead to a low-density halo. Sales said the team’s simulations identify conditions for the core collapse to occur in subhalos.

“To explain Draco’s high dark matter density, its initial halo concentration needs to be high,” she said. “More dark matter mass needs to be distributed in the inner halo. While this is true for both CDM and SIDM, for SIDM the core-collapse phenomenon can only occur if the concentration is high so that the collapse timescale is less than the age of the universe. On the other hand, Fornax has a low-concentrated subhalo, and hence its density remains low.”

The researchers stressed their current work mainly focuses on SIDM and does not make a critical assessment on how well CDM can explain both Draco and Fornax.

After the team used numerical simulations to properly take into account the dynamical interplay between dark matter self-interactions and tidal interactions, the researchers observed a striking result.

“The central dark matter of an SIDM subhalo could be increasing, contrary to usual expectations,” Sameie said. “Importantly, our simulations identify conditions for this phenomenon to occur in SIDM, and we show it can explain observations of Draco.”

The research team plans to extend the study to other satellite galaxies, including ultrafaint galaxies.

Yu, Sales, and Sameie were joined in the study by Mark Vogelsberger of the Massachusetts Institute of Technology and Jesús Zavala of the University of Iceland. Sameie is the first author of the research paper.

The research was supported by grants from the U.S. Department of Energy, National Aeronautics and Space Administration, NASA MIRO FIELDS Fellowship, National Science Foundation, the Hell

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From UC Riverside: “Ancestor of all animals identified in Australian fossils”

From UC Riverside

March 23, 2020
Holly Ober

An artist’s rendering of Ikaria wariootia. (Sohail Wasif/UCR)

A wormlike creature that lived more than 555 million years ago is the earliest bilaterian.

A team led by UC Riverside geologists has discovered the first ancestor on the family tree that contains most familiar animals today, including humans.

The tiny, wormlike creature, named Ikaria wariootia, is the earliest bilaterian, or organism with a front and back, two symmetrical sides, and openings at either end connected by a gut. The paper is published today in Proceedings of the National Academy of Sciences.

The earliest multicellular organisms, such as sponges and algal mats, had variable shapes. Collectively known as the Ediacaran Biota, this group contains the oldest fossils of complex, multicellular organisms. However, most of these are not directly related to animals around today, including lily pad-shaped creatures known as Dickinsonia that lack basic features of most animals, such as a mouth or gut.

The development of bilateral symmetry was a critical step in the evolution of animal life, giving organisms the ability to move purposefully and a common, yet successful way to organize their bodies. A multitude of animals, from worms to insects to dinosaurs to humans, are organized around this same basic bilaterian body plan.

Evolutionary biologists studying the genetics of modern animals predicted the oldest ancestor of all bilaterians would have been simple and small, with rudimentary sensory organs. Preserving and identifying the fossilized remains of such an animal was thought to be difficult, if not impossible.

For 15 years, scientists agreed that fossilized burrows found in 555 million-year-old Ediacaran Period deposits in Nilpena, South Australia, were made by bilaterians. But there was no sign of the creature that made the burrows, leaving scientists with nothing but speculation.

Scott Evans, a recent doctoral graduate from UC Riverside; and Mary Droser, a professor of geology, noticed miniscule, oval impressions near some of these burrows. With funding from a NASA exobiology grant, they used a three-dimensional laser scanner that revealed the regular, consistent shape of a cylindrical body with a distinct head and tail and faintly grooved musculature. The animal ranged between 2-7 millimeters long and about 1-2.5 millimeters wide, with the largest the size and shape of a grain of rice — just the right size to have made the burrows.

“We thought these animals should have existed during this interval, but always understood they would be difficult to recognize,” Evans said. “Once we had the 3D scans, we knew that we had made an important discovery.”

The researchers, who include Ian Hughes of UC San Diego and James Gehling of the South Australia Museum, describe Ikaria wariootia, named to acknowledge the original custodians of the land. The genus name comes from Ikara, which means “meeting place in the Adnyamathanha language. It’s the Adnyamathanha name for a grouping of mountains known as Wilpena Pound. The species name comes from Warioota Creek, which runs from the Flinders Ranges to Nilpena Station.

“Burrows of Ikaria occur lower than anything else. It’s the oldest fossil we get with this type of complexity,” Droser said. “Dickinsonia and other big things were probably evolutionary dead ends. We knew that we also had lots of little things and thought these might have been the early bilaterians that we were looking for.”

In spite of its relatively simple shape, Ikaria was complex compared to other fossils from this period. It burrowed in thin layers of well-oxygenated sand on the ocean floor in search of organic matter, indicating rudimentary sensory abilities. The depth and curvature of Ikaria represent clearly distinct front and rear ends, supporting the directed movement found in the burrows.

The burrows also preserve crosswise, “V”-shaped ridges, suggesting Ikaria moved by contracting muscles across its body like a worm, known as peristaltic locomotion. Evidence of sediment displacement in the burrows and signs the organism fed on buried organic matter reveal Ikaria probably had a mouth, anus, and gut.

“This is what evolutionary biologists predicted,” Droser said. “It’s really exciting that what we have found lines up so neatly with their prediction.”

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From UC Riverside: “A possible end to ‘forever’ chemicals”

From UC Riverside

March 10, 2020
Holly Ober

Excess electrons could help break the strong chemical bonds in products that contaminate water supplies.

Synthetic chemicals known as per- and polyfluoroalkyls, or PFAS, contain bonds between carbon and fluorine atoms considered the strongest in organic chemistry. Unfortunately, the widespread use of these nonbiodegradable products since the 1940s has contaminated many water supplies across America.

Engineers at UC Riverside have now shown in modeling experiments that using excess electrons shatters the carbon-fluorine bond of PFAS in water, leaving by-products that might even accelerate the process. The paper is published in Physical Chemistry Chemical Physics.

Impervious to heat, chemicals, and physical force, the carbon-fluorine bond makes PFAS ubiquitous in food packaging, stain and water repellent fabrics, polishes and waxes, firefighting foams, cleaning products, carpets and thousands of other common household and industrial products. The Environmental Protection Agency estimates that most of the population has been exposed to PFAS that accumulate in the body over time because these “forever chemicals” do not biodegrade.

Sharma Yamijala, a postdoctoral researcher in the Marlan and Rosemary Bourns College of Engineering and first author of the paper, ran simulations on both perfluorooctanoic acid and perfluorooctanesulfonic acid molecules, the most common PFA contaminants in the environment, surrounded by water molecules. He found that they instantly lost their fluorine atom in the presence of excess electrons.

The PFA molecules broke down into an intermediate chemical species whose composition could further accelerate the decomposition of other PFA molecules. The reaction also formed a hydrogen fluoride molecule. Whether or not these shortchain molecules are carcinogens at typical concentrations in water has not yet been determined.

“In a real water treatment scenario, the excess electrons could come from metal-containing compounds placed in the water under ultraviolet radiation. The electrons from these compounds will interact with the PFA molecules and break them,” Yamijala said.

The simulations describe in precise detail a process that scientists have known is possible.

“People knew you could do this but didn’t know why,” said Bryan Wong, an associate professor of chemical and environmental engineering and the paper’s senior author. “Our simulations define the bigger picture that we can refine to find ways to break down PFAs faster or more efficiently in the future.”

The research was supported by grants from the U.S. Department of Energy and the National Science Foundation.

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From UC Riverside: “Some domesticated plants ignore beneficial soil microbes”

From UC Riverside

March 10, 2020
Holly Ober

Domestication yielded bigger crops often at the expense of plant microbiomes.

While domestication of plants has yielded bigger crops, the process has often had a negative effect on plant microbiomes, making domesticated plants more dependent on fertilizer and other soil amendments than their wild relatives.

In an effort to make crops more productive and sustainable, researchers recommend reintroduction of genes from the wild relatives of commercial crops that restore domesticated plants’ ability to interact with beneficial soil microbes.

Thousands of years ago, people harvested small wild plants for food. Eventually, they selectively cultivated the largest ones until the plump cereals, legumes, and fruit we know today evolved. But through millennia of human tending, many cultivated plants lost some ability to interact with soil microbes that provide necessary nutrients. This has made some domesticated plants more dependent on fertilizer, one of the world’s largest sources of nitrogen and phosphorous pollution and a product that consumes fossil fuels to produce.

“I was surprised how completely hidden these changes can be,” said Joel Sachs, a professor of biology at UC Riverside and senior author of a paper published today in Trends in Ecology and Evolution. “We’re so focused on above ground traits that we’ve been able to massively reshape plants while ignoring a suite of other characteristics and have inadvertently bred plants with degraded capacity to gain benefits from microbes.”

Bacteria and fungi form intimate associations with plant roots that can dramatically improve plant growth. These microbes help break down soil elements like phosphorous and nitrogen that the plants absorb through their roots. The microbes also get resources from the plants in a mutually beneficial, or symbiotic, relationship. When fertilizer or other soil amendments make nutrients freely available, plants have less need to interact with microbes.

Sachs and first author Stephanie Porter of Washington State University, Vancouver, reviewed 120 studies of microbial symbiosis in plants and concluded that many types of domesticated plants show a degraded capacity to form symbiotic communities with soil microbes.

“The message of our paper is that domestication has hidden costs,” Sachs said. “When plants are selected for a small handful of traits like making a bigger seed or faster growth, you can lose a lot of important traits relating to microbes along the way.”

This evolutionary loss has turned into a loss for the environment as well.

Excess nitrogen and phosphorous from fertilizer can leach from fields into waterways, leading to algae overgrowth, low oxygen levels, and dead zones. Nitrogen oxide from fertilizer enters the atmosphere, contributing to air pollution. Fossil fuels are also consumed to manufacture fertilizers.

Some companies have begun selling nitrogen-fixing bacteria as soil amendments to make agriculture more sustainable, but Sachs said these amendments don’t work well because some domesticated plants can no longer pick up those beneficial microbes from the soil.

“If we’re going to fix these problems, we need to figure out which traits have been lost and which useful traits have been maintained in the wild relative,” Sachs said. “Then breed the wild and domesticated together to recover those traits.”

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From UC Riverside: “Ancient meteorite site on Earth could reveal new clues about Mars’ past”

From UC Riverside

February 26, 2020
Jules Bernstein

A sample of suevite rock formed nearly 15 million years ago by the Ries Crater meteorite impact. Similarly impact-generated rocks exist on the rims of ancient crater lakes on Mars. (NASA)

Scientists have devised new analytical tools to break down the enigmatic history of Mars’ atmosphere — and whether life was once possible there.

A paper detailing the work was published today in the journal Science Advances. It could help astrobiologists understand the alkalinity, pH and nitrogen content of ancient waters on Mars, and by extension, the carbon dioxide composition of the planet’s ancient atmosphere.

Jezero Crater, landing site for the upcoming Mars 2020 rover mission. (NASA/JPL/JHUAPL/MSSS/Brown University)

Mars of today is too cold to have liquid water on its surface, a requirement for hosting life as we know it.

“The question that drives our interests isn’t whether there’s life on present-day Mars,” said Tim Lyons, UCR distinguished professor of biogeochemistry. “We are driven instead by asking whether there was life on Mars billions of years ago, which seems significantly more likely.”

However, “Overwhelming evidence exists that Mars had liquid water oceans roughly 4 billion years ago,” Lyons noted.

The central question astrobiologists ask is how that was possible. The red planet is farther from the sun than Earth is, and billions of years ago the sun generated less heat than it does today.

“To have made the planet warm enough for liquid surface water, its atmosphere would likely have needed an immense amount of greenhouse gas, carbon dioxide specifically,” explained Chris Tino, a UCR graduate student and co-first-author of the paper along with Eva Stüeken, a lecturer at the University of St. Andrews in Scotland.

Since sampling Mars’ atmosphere from billions of years ago to learn its carbon dioxide content is impossible, the team concluded that a site on Earth whose geology and chemistry bear similarities to the Martian surface might provide some of the missing pieces. They found it in southern Germany’s Nordlinger Ries crater.

Formed roughly 15 million years ago after being struck by a meteorite, Ries crater features layers of rocks and minerals better preserved than almost anywhere on Earth.

The Mars 2020 rover will land in a similarly structured, well-preserved ancient crater. Both places featured liquid water in their distant past, making their chemical compositions comparable.

According to Tino, it’s unlikely that ancient Mars had enough oxygen to have hosted complex life forms like humans or animals.

However, some microorganisms could have survived if ancient Martian water had both a neutral pH level and was highly alkaline. Those conditions imply sufficient carbon dioxide in the atmosphere — perhaps thousands of times more than what surrounds Earth today — to warm the planet and make liquid water possible.

While pH measures the concentration of hydrogen ions in a solution, alkalinity is a measure dependent on several ions and how they interact to stabilize pH.

“Ries crater rock samples have ratios of nitrogen isotopes that can best be explained by high pH,” Stüeken said. “What’s more, the minerals in the ancient sediments tell us that alkalinity was also very high.”

However, Martian samples with mineral indicators for high alkalinity and nitrogen isotope data pointing to relatively low pH would demand extremely high levels of carbon dioxide in the past atmosphere.

The resulting carbon dioxide estimates could help solve the long-standing mystery of how an ancient Mars located so far from a faint early sun could have been warm enough for surface oceans and perhaps life. How such high levels could have been maintained and what might have lived beneath them remain important questions.

“Before this study, it wasn’t clear that something as straightforward as nitrogen isotopes could be used to estimate the pH of ancient waters on Mars; pH is a key parameter in calculating the carbon dioxide in the atmosphere,” Tino said.

Funding for this study came from the NASA Astrobiology Institute, where Lyons leads the Alternative Earths team based at UCR.

Included in the study were Gernot Arp of the Georg-August University of Göttingen and Dietmar Jung of the Bavarian State Office for the Environment.

When samples from NASA’s Mars 2020 rover mission are brought back to Earth, they could be analyzed for their nitrogen isotope ratios. These data could confirm the team’s suspicion that very high levels of carbon dioxide made liquid water possible and maybe even some forms of microbial life long ago.

“It could be 10-20 years before samples are brought back to Earth,” Lyons said. “But I am delighted to know that we have perhaps helped to define one of the first questions to ask once these samples are distributed to labs in the U.S. and throughout the world.”

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From UC Riverside: “Connecting the world through images and sound”

From UC Riverside

February 20, 2020
Sandra Baltazar Martinez
Senior Public Information Officer
(951) 827-2653
sandrab.martinez@ucr.edu

UCR professor’s research weaves together an immersive visual and auditory presentation of Riverside, Brazil, India, Russia, and Germany.

Within a three-year span, Paulo C. Chagas traveled to four countries, collecting sounds and images along the way.

The videos, photos, and sounds were captured using a 360-degree camera and ambisonics microphone as he walked the citrus fields here in Riverside, and the streets of Brazil, India, Russia, and Germany. This exploration of geographic and cultural contexts is now a visual and auditory exhibit titled “Sound Imaginations,” which opens Feb. 29 at UC Riverside’s Culver Center of the Arts in downtown Riverside.

“The idea is to show that sound is synesthetic,” said Chagas, a professor of composition in UCR’s Department of Music. “I want to make a connection as humans, to be inspired by listening cultures. When you look at different aspects of life, sound and vision are very important components. With this project, I want to emphasize both the ambiguity and the plurality of life.”

UCR professor Paulo C. Chagas in front of a 360 camera lens. (Courtesy Paulo C. Chagas)

Chagas captured a variety of stunning sights and experiences, including a religious procession in India; a warm, sunny day at a Brazilian park; as well as colorful Russian architecture. The images were then layered with sounds of machines, people talking, birds chirping — much like musical instruments in an orchestra.

The project was funded by UCR’s Center for Ideas and Society, and Chagas will incorporate his work into a spring quarter course called “sound studies and sound art.”

Chagas said he used the relationship between sound and images to gain insight into how different cultures have used different approaches to the act of listening, how individuals listen in different ways, and how people listen to surrounding machines, living beings, spaces, and cultures.

Chagas’ exhibit includes nine screens and eight speakers that will provide an immersive multivisual and multisound channel projection.

“Sound Imaginations” will open from Feb. 29-March 8. An opening reception is scheduled for Saturday, Feb. 29, 6-9 p.m. and an artist talk is set for Thursday, March 5, at 6 p.m.

For hours of operation and admission, visit UCR Culver Center of the Arts.

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From UC Riverside: “Astronomers discover unusual monster galaxy in the very early universe”

From UC Riverside

February 5, 2020
Iqbal Pittalwala

XMM-2599 lived fast and died young, says UC Riverside-led international team.

Gillian Wilson (left) and Benjamin Forrest. (UCR/I. Pittalwala)

The three panels show, from top to bottom, what XMM-2599’s evolutionary trajectory might be, beginning as a dusty star-forming galaxy, then becoming a dead galaxy, and perhaps ending up as a “brightest cluster galaxy,” or BCG. (NRAO/AUI/NSF/B. Saxton; NASA/ESA/R. Foley; NASA/StScI)

An international team of astronomers led by scientists at the University of California, Riverside, has found an unusual monster galaxy that existed about 12 billion years ago, when the universe was only 1.8 billion years old.

Dubbed XMM-2599, the galaxy formed stars at a high rate and then died. Why it suddenly stopped forming stars is unclear.

“Even before the universe was 2 billion years old, XMM-2599 had already formed a mass of more than 300 billion suns, making it an ultramassive galaxy,” said Benjamin Forrest, a postdoctoral researcher in the UC Riverside Department of Physics and Astronomy and the study’s lead author. “More remarkably, we show that XMM-2599 formed most of its stars in a huge frenzy when the universe was less than 1 billion years old, and then became inactive by the time the universe was only 1.8 billion years old.”

The team used spectroscopic observations from the W. M. Keck Observatory’s powerful Multi-Object Spectrograph for Infrared Exploration, or MOSFIRE, to make detailed measurements of XMM-2599 and precisely quantify its distance.

Keck/MOSFIRE on Keck 1, Mauna Kea, Hawaii, USA

Keck 1, operated by Caltech and the University of California, Maunakea Hawaii USA, 4,207 m (13,802 ft)

Study results appear in The Astrophysical Journal.

“In this epoch, very few galaxies have stopped forming stars, and none are as massive as XMM-2599,” said Gillian Wilson, a professor of physics and astronomy at UCR in whose lab Forrest works. “The mere existence of ultramassive galaxies like XMM-2599 proves quite a challenge to numerical models. Even though such massive galaxies are incredibly rare at this epoch, the models do predict them. The predicted galaxies, however, are expected to be actively forming stars. What makes XMM-2599 so interesting, unusual, and surprising is that it is no longer forming stars, perhaps because it stopped getting fuel or its black hole began to turn on. Our results call for changes in how models turn off star formation in early galaxies.”

The research team found XMM-2599 formed more than 1,000 solar masses a year in stars at its peak of activity — an extremely high rate of star formation. In contrast, the Milky Way forms about one new star a year.

“XMM-2599 may be a descendant of a population of highly star-forming dusty galaxies in the very early universe that new infrared telescopes have recently discovered,” said Danilo Marchesini, an associate professor of astronomy at Tufts University and a co-author on the study.

The evolutionary pathway of XMM-2599 is unclear.

“We have caught XMM-2599 in its inactive phase,” Wilson said. “We do not know what it will turn into by the present day. We know it cannot lose mass. An interesting question is what happens around it. As time goes by, could it gravitationally attract nearby star-forming galaxies and become a bright city of galaxies?”

Co-author Michael Cooper, a professor of astronomy at UC Irvine, said this outcome is a strong possibility.

“Perhaps during the following 11.7 billion years of cosmic history, XMM-2599 will become the central member of one of the brightest and most massive clusters of galaxies in the local universe,” he said. “Alternatively, it could continue to exist in isolation. Or we could have a scenario that lies between these two outcomes.”

The team has been awarded more time at the Keck Observatory to follow up on unanswered questions prompted by XMM-2599.

“We identified XMM-2599 as an interesting candidate with imaging alone,” said co-author Marianna Annunziatella, a postdoctoral researcher at Tufts University. “We used Keck to better characterize and confirm its nature and help us understand how monster galaxies form and die. MOSFIRE is one of the most efficient and effective instruments in the world for conducting this type of research.”

Other researchers taking part include Daniel Lange-Vagle and Theodore Peña of Tufts University; Adam Muzzin and Cemile Marsan of York University, Canada; Ian McConachie and Jeffrey Chan of UCR; Percy Gomez of Keck Observatory; Erin Kado-Fong of Princeton University; Francesco La Barbera of INAF–Osservatorio Astronomico di Capodimonte, Italy; Ivo Labbe of Swinburne University of Technology, Australia; Julie Nantais of Andrés Bello National University, Santiago, Chile; Mario Nonino of Astronomical Observatory of Trieste, Italy; Paolo Saracco of Astronomical Observatory of Brera, Italy; Mauro Stefanon of Leiden University, Netherlands; and Remco F. J. van der Burg of the European Southern Observatory, Germany.

Wilson led the W. M. Keck Observatory data acquisition. Forrest led the processing and analysis.

The study was supported by grants from the National Science Foundation and NASA.

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From UC Riverside: “Scientists short-circuit maturity in insects, opening new paths to disease prevention”

From UC Riverside

January 28, 2020
Jules Bernstein

Image shows the developing brain of an immature fruit fly. Green color shows the cell layer forming the blood-brain barrier, which physically separates the brain from the circulation. (Yamanaka/UCR)

Puberty-controlling hormone does not travel freely into the brain as previously thought.

New research from UC Riverside shows scientists may soon be able to prevent disease-spreading mosquitoes from maturing. Using the same gene-altering techniques, they may also be able help boost reproduction in beneficial bumblebees.

The research shows that, contrary to previous scientific belief, a hormone required for sexual maturity in insects cannot travel across a mass of cells separating the blood from the brain — unless it is aided by a transporter protein molecule.

“Before this finding, there had been a longstanding assumption that steroid hormones pass freely through the blood-brain barrier,” said Naoki Yamanaka, an assistant professor of entomology at UCR, who led the research. “We have shown that’s not so.”

The study, published this month in the journal Current Biology, details the effects on sexual maturity in fruit flies when the transporter protein is blocked.

Blocking the transporter not only prevented the steroid from entering the brain, it also permanently altered the flies’ behavior. When flies are in their infancy or “maggot” stage, they usually stay on or in a source of food.

Later, as they prepare to enter a more adult phase of life, they exhibit “wandering behavior,” in which they come out of their food to find a place to shed their outer body layer and transform into an adult fly.

When the transporter gene was blocked, Yamanaka said the flies entered a median stage between infancy and adulthood, but never wandered out of their food, and died slowly afterward without ever reaching adulthood or reproducing.

“Our biggest motivation for this study was to challenge the prevailing assumption about free movement of steroids past the blood-brain barrier, by using fruit flies as a model species,” Yamanaka said. “In the long run, we’re interested in controlling the function of steroid hormone transporters to manipulate insect and potentially human behaviors.”

Currently, Yamanaka is examining whether altering genes in mosquitoes could have a similar effect. Since mosquitoes are vectors for numerous diseases, including Zika, West Nile Virus, malaria and Dengue fever, there is great potential for the findings to improve human health.

Conversely, there may be a way to alter the genes to manipulate reproduction in beneficial insects as well, in order to help them. Bumblebees, whose populations have been declining in recent years, pollinate many favorite human food crops.

Also, there is the potential for this work to more directly impact humans. Steroid hormones affect a variety of behaviors and reactions in the human body. For example, the human body under stress makes a steroid hormone called cortisol. It enters the brain so humans can cope with the stressful situation.

However, when chronic stress is experienced, cortisol can build up in the brain and cause multiple issues. “If the same machinery exists for cortisol in humans, we may be able to block the transporter in the blood-brain barrier to protect our brain from chronic stress,” Yamanaka said.

“It’s an exciting finding,” said Yamanaka. “It was just in flies, but more than 70% of human disease-related genes have equivalents in flies, so there is a good chance this holds true for humans too.”

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From UC Riverside: “Detection of very high frequency magnetic resonance could revolutionize electronics”

From UC Riverside

January 27, 2020
Iqbal Pittalwala

UC Riverside-led research has applications in ultrafast and spin-based nanoscale devices.

Physicist Jing Shi

A team of physicists has discovered an electrical detection method for terahertz electromagnetic waves, which are extremely difficult to detect. The discovery could help miniaturize the detection equipment on microchips and enhance sensitivity.

Simple experiment explains magnetic resonance. UC Riverside physics students design a table-top experiment for the classroom.

Terahertz is a unit of electromagnetic wave frequency: One gigahertz equals 1 billion hertz; 1 terahertz equals 1,000 gigahertz. The higher the frequency, the faster the transmission of information. Cell phones, for example, operate at a few gigahertz.

The finding, reported today in Nature, is based on a magnetic resonance phenomenon in anti-ferromagnetic materials. Such materials, also called antiferromagnets, offer unique advantages for ultrafast and spin-based nanoscale device applications.

The researchers, led by physicist Jing Shi of the University of California, Riverside, generated a spin current, an important physical quantity in spintronics, in an antiferromagnet and were able to detect it electrically. To accomplish this feat, they used terahertz radiation to pump up magnetic resonance in chromia to facilitate its detection.

In ferromagnets, such as a bar magnet, electron spins point in the same direction, up or down, thus providing collective strength to the materials. In antiferromagnets, the atomic arrangement is such that the electron spins cancel each other out, with half of the spins pointing in the opposite direction of the other half, either up or down.

The electron has a built-in spin angular momentum, which can precess the way a spinning top precesses around a vertical axis. When the precession frequency of electrons matches the frequency of electromagnetic waves generated by an external source acting on the electrons, magnetic resonance occurs and is manifested in the form of a greatly enhanced signal that is easier to detect.

In order to generate such magnetic resonance, the team of physicists from UC Riverside and UC Santa Barbara worked with 0.24 terahertz of radiation produced at the Institute for Terahertz Science and Technology’s Terahertz Facilities at the Santa Barbara campus. This closely matched the precession frequency of electrons in chromia. The magnetic resonance that followed resulted in the generation of a spin current that the researchers converted into a DC voltage.

“We were able to demonstrate that antiferromagnetic resonance can produce an electrical voltage, a spintronic effect that has never been experimentally done before,” said Shi, a professor in the Department of Physics and Astronomy.

Shi, who directs Department of Energy-funded Energy Frontier Research Center Spins and Heat in Nanoscale Electronic Systems, or SHINES, at UC Riverside, explained subterahertz and terahertz radiation are a challenge to detect. Current communication technology uses gigahertz microwaves.

“For higher bandwidth, however, the trend is to move toward terahertz microwaves,” Shi said. “The generation of terahertz microwaves is not difficult, but their detection is. Our work has now provided a new pathway for terahertz detection on a chip.”

Although antiferromagnets are statically uninteresting, they are dynamically interesting. Electron spin precession in antiferromagnets is much faster than in ferromagnets, resulting in frequencies that are two-three orders of magnitude higher than the frequencies of ferromagnets — thus allowing faster information transmission.

“Spin dynamics in antiferromagnets occur at a much shorter timescale than in ferromagnets, which offers attractive benefits for potential ultrafast device applications,” Shi said.

Antiferromagnets are ubiquitous and more abundant than ferromagnets. Many ferromagnets, such as iron and cobalt, become antiferromagnetic when oxidized. Many antiferromagnets are good insulators with low dissipation of energy. Shi’s lab has expertise in making ferromagnetic and antiferromagnetic insulators.

Shi’s team developed a bilayer structure comprised of chromia, an antiferromagnetic insulator, with a layer of metal on top of it to serve as the detector to sense signals from chromia.

Shi explained that electrons in chromia remain local. What crosses the interface is information encoded in the precessing spins of the electrons.

“The interface is critical,” he said. “So is spin sensitivity.”

The researchers addressed spin sensitivity by focusing on platinum and tantalum as metal detectors. If the signal from chromia originates in spin, platinum and tantalum register the signal with opposite polarity. If the signal is caused by heating, however, both metals register the signal with identical polarity.

“This is the first successful generation and detection of pure spin currents in antiferromagnetic materials, which is a hot topic in spintronics,” Shi said. “Antiferromagnetic spintronics is a major focus of SHINES.”

The technology has been disclosed to UCR Technology Commercialization, assigned UC case number 2019-105, and is patent pending.

Shi was joined in the study by Junxue Li, Ran Cheng, Mark Lohmann, Wei Yuan, Mohammed Aldosary, and Peng Wei of UC Riverside; and C. Blake Wilson, Marzieh Kavand, Nikolay Agladze, and Mark S. Sherwin at UC Santa Barbara.

The research at UC Riverside was supported by SHINES.

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From UC Riverside: “Can I mix those chemicals? There’s an app for that!”

From UC Riverside

January 23, 2020
Holly Ober

New technology can find the safest way to store and dispose of reactive chemicals.

Improperly mixed chemicals cause a shocking number of fires, explosions, and injuries in laboratories, businesses, and homes each year.

A new open source computer program called ChemStor developed by engineers at the University of California, Riverside, can prevent these dangerous situations by telling users if it is unsafe to mix certain chemicals.

A visual representation showing how graph coloring register allocation works. (Jason Ott/UCR)

The Centers for Disease Control estimates 4,500 injuries a year are caused by the mixture of incompatible pool cleaning chemicals, half of which occur in homes. Even in laboratories and factories where workers are trained in safe storage protocols, mix-ups and accidents happen, often after chemicals are inadvertently combined in a waste container.

The UC Riverside engineers’ work is published in the Journal of Chemical Information and Modeling. Their program adapts a computer science strategy to allocate resources for efficient processor use, known as graph coloring register allocation. In this system, resources are colored and organized according to a rule that states adjacent data points, or nodes, sharing an edge cannot also share a color.

“We color a graph such that no two nodes that share an edge have the same color,” said first author Jason Ott, a doctoral student in computer science who led the research.

“The idea comes from maps,” explained co-author William Grover, an assistant professor of bioengineering in the Marlan and Rosemary Bourns College of Engineering with a background in chemistry. “In a map of the U.S., for example, no two adjacent states share a color, which makes them easy to tell apart.”

ChemStor draws from an Environmental Protection Agency library of 9,800 chemicals, organized into reactivity groups. It then builds a chemical interaction graph based on the reactivity groups and computes the smallest number of colors that will color the graph such that no two chemicals that can interact also share the same color.

ChemStor next assigns all the chemicals of each color to a storage or waste container after confirming there is enough space. Chemicals with the same color can be stored together without a dangerous reaction, while chemicals with different colors cannot.

If two or more chemicals can be combined in the same cabinet or added to a waste container without forming possibly dangerous combinations of chemicals, ChemStor determines the configuration is safe. ChemStor also indicates if no safe storage or disposal configuration can be found.

Grover, who experienced a destructive lab fire caused by incompatible chemicals during his days as an undergraduate, said he takes the threat very seriously.

“I’m responsible for the safety of the people in my lab, and ChemStor would be like a safety net under our already strict storage protocols,” Grover said.

ChemStor’s functionality is currently limited to a command line interface only, where the user manually enters the type of chemicals and amount of storage space into a computer.

Updates are forthcoming to make ChemStor more user-friendly, including a smartphone app utilizing the camera to gather information about chemicals and storage options, as well as an integration with digital voice assistants, some of which have already begun to be developed specifically for chemists, making ChemStor a natural addition.

“Any system can communicate with ChemStor as long as the input is fashioned in a way that ChemStor expects,” Ott said. The code is available here.

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.