Science
Further Back in Time Than Ever Before: Distribution of Dark Matter Around Galaxies 12 Billion Years Ago Revealed – SciTechDaily


The radiation residue from the Big Bang, distorted by dark matter 12 billion years ago. Credit: Reiko Matsushita
Scientists investigated the nature of dark matter surrounding galaxies seen as they were 12 billion years ago, billions of years further back in time than ever before. Their findings offer the tantalizing possibility that the fundamental rules of cosmology may differ when examining the early history of our universe. The collaboration was led by scientists at <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>Nagoya University in Japan and the findings were published today (August 1) in the journal Physical Review Letters.
Seeing something that happened such a long time ago is challenging. Because of the speed of light is finite, we see distant galaxies not as they are today, but as they were billions of years ago. But even more difficult is observing dark matter, which does not emit light.
“It was a crazy idea. No one realized we could do this.” — Professor Masami Ouchi
Consider a distant source galaxy, even farther away than the target galaxy whose dark matter one wants to investigate. As predicted by Einstein’s theory of general relativity, the gravitational attraction of the foreground galaxy, including its dark matter, distorts the surrounding space and time. As the light from the source galaxy travels through this distortion in spacetime, it bends, changing the apparent shape of the galaxy. The greater the amount of dark matter, the greater the resulting distortion. Therefore, astronomers can measure the amount of dark matter around the foreground galaxy (the “lens” galaxy) from the distortion.
However, beyond a certain threshold, scientists encounter a problem. In the deepest reaches of the universe, the galaxies are incredibly faint. As a result, the farther away from Earth we look, the less effective the gravitational lensing technique becomes. Because the lensing distortion is subtle and difficult to detect in most cases, many background galaxies are needed to detect the signal.
Most previous studies have remained stuck at the same limits. Unable to detect enough distant source galaxies to measure the distortion, they could only analyze dark matter from no more than 8-10 billion years ago. These limitations left open the question of the distribution of dark matter between this time and 13.7 billion years ago, around the beginning of our universe.
To overcome these challenges and observe dark matter from the farthest reaches of the universe, a team of researchers led by Hironao Miyatake from Nagoya University, in collaboration with the University of Tokyo, the National Astronomical Observatory of Japan, and Princeton University, used a different source of background light, the microwaves released from the Big Bang itself.
First, using data from the observations of the Subaru Hyper Suprime-Cam Survey (HSC), the team identified 1.5 million lens galaxies using visible light, selected to be seen 12 billion years ago.
Next, to overcome the lack of galaxy light even farther away, they employed microwaves from the cosmic microwave background (CMB), the radiation residue from the <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>Big Bang. Using microwaves observed by the European Space Agency’s Planck satellite, the team measured how the dark matter around the lens galaxies distorted the microwaves.
“Look at dark matter around distant galaxies?” asked Professor Masami Ouchi of the University of Tokyo, who made many of the observations. “It was a crazy idea. No one realized we could do this. But after I gave a talk about a large distant galaxy sample, Hironao came to me and said it may be possible to look at dark matter around these galaxies with the CMB.”
“Most researchers use source galaxies to measure dark matter distribution from the present to eight billion years ago,” added Assistant Professor Yuichi Harikane of the Institute for Cosmic Ray Research, University of Tokyo. “However, we could look further back into the past because we used the more distant CMB to measure dark matter. For the first time, we were measuring dark matter from almost the earliest moments of the universe.”
After a preliminary analysis, the scientists soon realized that they had a large enough sample to detect the distribution of dark matter. Combining the large distant galaxy sample and the lensing distortions in CMB, they detected dark matter even further back in time, from 12 billion years ago. This is only 1.7 billion years after the beginning of the universe, and thus these galaxies are seen soon after they first formed.
“I was happy that we opened a new window into that era,” Miyatake said. “12 billion years ago, things were very different. You see more galaxies that are in the process of formation than at the present; the first galaxy clusters are starting to form as well.” Galaxy clusters comprise 100-1000 galaxies bound by gravity with large amounts of dark matter.
“This result gives a very consistent picture of galaxies and their evolution, as well as the dark matter in and around galaxies, and how this picture evolves with time,” said Neta Bahcall, Eugene Higgins Professor of Astronomy, professor of astrophysical sciences, and director of undergraduate studies at <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>Princeton University.
One of the most exciting discoveries from the study was related to the clumpiness of dark matter. According to the standard theory of cosmology, the Lambda-CDM model, subtle fluctuations in the CMB form pools of densely packed matter by attracting surrounding matter through gravity. This creates inhomogeneous clumps that form stars and galaxies in these dense regions. The group’s findings suggest that their clumpiness measurement was lower than predicted by the Lambda-CDM model.
Miyatake is enthusiastic about the possibilities. “Our finding is still uncertain,” he said. “But if it is true, it would suggest that the entire model is flawed as you go further back in time. This is exciting because if the result holds after the uncertainties are reduced, it could suggest an improvement of the model that may provide insight into the nature of dark matter itself.”
“At this point, we will try to get better data to see if the Lambda-CDM model is actually able to explain the observations that we have in the universe,” said Andrés Plazas Malagón, associate research scholar at Princeton University. “And the consequence may be that we need to revisit the assumptions that went into this model.”
“One of the strengths of looking at the universe using large-scale surveys, such as the ones used in this research, is that you can study everything that you see in the resulting images, from nearby asteroids in our solar system to the most distant galaxies from the early universe. You can use the same data to explore a lot of new questions,” said Michael Strauss, professor and chair of the Department of Astrophysical Sciences at Princeton University.
This study used data available from existing telescopes, including Planck and Subaru. The group has only reviewed a third of the Subaru Hyper Suprime-Cam Survey data. The next step will be to analyze the entire data set, which should allow for a more precise measurement of the dark matter distribution. In the future, the research team expects to use an advanced data set like the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) to explore more of the earliest parts of space. “LSST will allow us to observe half the sky,” Harikane said. “I don’t see any reason we couldn’t see the dark matter distribution 13 billion years ago next.”
Reference: “First Identification of a CMB Lensing Signal Produced by 1.5 Million Galaxies at z~4: Constraints on Matter Density Fluctuations at High Redshift” by Hironao Miyatake, Yuichi Harikane, Masami Ouchi, Yoshiaki Ono, Nanaka Yamamoto, Atsushi J. Nishizawa, Neta Bahcall, Satoshi Miyazaki and Andrés A. Plazas Malagón, 1 August 2022, Physical Review Letters.
DOI: 10.1103/PhysRevLett.129.061301
Science
Meet the Canadian astronauts up for a seat on the Artemis II mission to the moon


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This Sunday, NASA and the Canadian Space Agency (CSA) will announce the four astronauts that will be blasting off to fly around the moon for the Artemis II mission, one of whom will be a Canadian astronaut.
The Artemis II mission will be the first crewed mission to orbit the moon in half a century, and the inclusion of a Canadian astronaut on the mission will make Canada the second country to have an astronaut fly around the moon.
In November 2024, NASA’s Kennedy Space Center in Florida will launch the four astronauts into space for the Artemis II mission. They will pilot the Orion spacecraft around the Earth and then around the moon before returning home.
It’s the second step of a project that started last year with the unmanned Artemis I mission. The Artemis missions help to test the launch system and the spacecraft itself. The end goal is for scientists to construct a Lunar Gateway at the moon — a space station that could serve as a jumping off point for further deep space exploration.
A trailer for the crew announcement was posted by NASA on Wednesday.
There are currently four active Canadian astronauts, but we won’t know until Sunday who will be the first Canadian astronaut to fly around the moon.
THE CANDIDATES
Joshua Kutryk
Kutryk was born in Fort Saskatchewan, Alberta and grew up on a cattle farm in eastern Alberta. He is a member of the Canadian Armed Forces, and has been deployed in Libya and Afghanistan in the past.
He worked as an experimental test pilot and fighter pilot in Cold Lake, Alberta before he was recruited by the CSA. He worked on numerous test flight projects as well as on improving the safety of fighter jets such as the CF-18.
Kutryk made it to the top 16 candidates for the CSA in 2009, but wasn’t selected until CSA’s 2017 recruitment campaign.
He obtained the official title of astronaut in January 2020.
Jennifer Sidey-Gibbons
Sidey-Gibbons comes from Calgary, Alberta, and first worked with the CSA while studying mechanical engineering at McGill University, where she conducted research on flame propagation in microgravity in collaboration with the agency.
Before joining CSA, she lived and worked in the U.K. as an assistant professor in the Department of Engineering at the University of Cambridge. Her research there focused on how to develop low-emission combusted for gas turbine engines.
She was selected by the CSA in 2017 as a recruit along with Kutryk, and obtained the official title of astronaut in January 2020.
Jeremy Hansen
Hansen was born in London, Ontario and spent his childhood first on a farm near Ailsa Craig, Ontario, and then Ingersoll, Ontario. He is married with three children.
By age 17, he had already obtained glider and private pilot licences through the Air Cadet Program. He is a member of the Canadian Armed Forces and served as a CF-18 fighter pilot before becoming an astronaut.
Hansen graduated as an astronaut in 2011, after being selected as one of two recruits for the CSA in 2009. He currently represents the CSA at NASA and works at the Mission Control Center, serving as the point of connection between the ground and the International Space Station (ISS). He also helps to train astronauts at NASA, the first Canadian to do so.
David Saint-Jacques
Saint-Jacques grew up in Saint-Lambert, Quebec, near Montreal, and is married with three children.
Before joining the CSA, he worked as a medical doctor in Puvirnituq, Nunavik, an Inuit community in northern Quebec. He also works as an adjunct professor of family medicine at McGill University. As a biomedical engineer, he has worked in France and Hungary, and helped to develop optics systems for telescopes and arrays used at observatories in Japan, Hawaii and the Canary Islands.
He was selected as a recruit in 2009 by the CSA and graduated in 2011 from the NASA astronaut program. He has since worked with the Robotics Branch of the NASA Astronaut Office, as a support astronaut for various ISS missions and as the mission control radio operator for a number of resupply missions for the ISS.
In December 2018, Saint-Jacques flew to the ISS to complete a 204-day mission, which is the longest mission any Canadian astronaut has carried out in space to date. During this time, he became the fourth CSA astronaut to conduct a spacewalk and the first CSA astronaut to catch a visiting spacecraft using the Canadarm2.





Science
Stressed plants emit airborne sounds that can be detected from more than a meter away


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What does a stressed plant sound like? A bit like bubble-wrap being popped. Researchers in Israel report in the journal Cell on March 30 that tomato and tobacco plants that are stressed—from dehydration or having their stems severed—emit sounds that are comparable in volume to normal human conversation. The frequency of these noises is too high for our ears to detect, but they can probably be heard by insects, other mammals, and possibly other plants.
“Even in a quiet field, there are actually sounds that we don’t hear, and those sounds carry information,” says senior author Lilach Hadany, an evolutionary biologist and theoretician at Tel Aviv University. “There are animals that can hear these sounds, so there is the possibility that a lot of acoustic interaction is occurring.”
Although ultrasonic vibrations have been recorded from plants before, this is the first evidence that they are airborne, a fact that makes them more relevant for other organisms in the environment. “Plants interact with insects and other animals all the time, and many of these organisms use sound for communication, so it would be very suboptimal for plants to not use sound at all,” says Hadany.
The researchers used microphones to record healthy and stressed tomato and tobacco plants, first in a soundproofed acoustic chamber and then in a noisier greenhouse environment. They stressed the plants via two methods: by not watering them for several days and by cutting their stems. After recording the plants, the researchers trained a machine-learning algorithm to differentiate between unstressed plants, thirsty plants, and cut plants.
The team found that stressed plants emit more sounds than unstressed plants. The plant sounds resemble pops or clicks, and a single stressed plant emits around 30–50 of these clicks per hour at seemingly random intervals, but unstressed plants emit far fewer sounds. “When tomatoes are not stressed at all, they are very quiet,” says Hadany.
Water-stressed plants began emitting noises before they were visibly dehydrated, and the frequency of sounds peaked after five days with no water before decreasing again as the plants dried up completely. The types of sound emitted differed with the cause of stress. The machine-learning algorithm was able to accurately differentiate between dehydration and stress from cutting and could also discern whether the sounds came from a tomato or tobacco plant.
Although the study focused on tomato and tobacco plants because of their ease to grow and standardize in the laboratory, the research team also recorded a variety of other plant species. “We found that many plants—corn, wheat, grape, and cactus plants, for example—emit sounds when they are stressed,” says Hadany.


The exact mechanism behind these noises is unclear, but the researchers suggest that it might be due to the formation and bursting of air bubbles in the plant’s vascular system, a process called cavitation.
Whether or not the plants are producing these sounds in order to communicate with other organisms is also unclear, but the fact that these sounds exist has big ecological and evolutionary implications. “It’s possible that other organisms could have evolved to hear and respond to these sounds,” says Hadany. “For example, a moth that intends to lay eggs on a plant or an animal that intends to eat a plant could use the sounds to help guide their decision.”
Other plants could also be listening in and benefiting from the sounds. We know from previous research that plants can respond to sounds and vibrations: Hadany and several other members of the team previously showed that plants increase the concentration of sugar in their nectar when they “hear” the sounds made by pollinators, and other studies have shown that plants change their gene expression in response to sounds. “If other plants have information about stress before it actually occurs, they could prepare,” says Hadany.


Sound recordings of plants could be used in agricultural irrigation systems to monitor crop hydration status and help distribute water more efficiently, the authors say.
“We know that there’s a lot of ultrasound out there—every time you use a microphone, you find that a lot of stuff produces sounds that we humans cannot hear—but the fact that plants are making these sounds opens a whole new avenue of opportunities for communication, eavesdropping, and exploitation of these sounds,” says co-senior author Yossi Yovel, a neuro-ecologist at Tel Aviv University.
“So now that we know that plants do emit sounds, the next question is—’who might be listening?'” says Hadany. “We are currently investigating the responses of other organisms, both animals and plants, to these sounds, and we’re also exploring our ability to identify and interpret the sounds in completely natural environments.”
More information:
Lilach Hadany, Sounds emitted by plants under stress are airborne and informative, Cell (2023). DOI: 10.1016/j.cell.2023.03.009. www.cell.com/cell/fulltext/S0092-8674(23)00262-3
Journal information:
Cell
Provided by
Cell Press
Citation:
Stressed plants emit airborne sounds that can be detected from more than a meter away (2023, March 30)
retrieved 30 March 2023
from https://phys.org/news/2023-03-stressed-emit-airborne-meter.html
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part may be reproduced without the written permission. The content is provided for information purposes only.





Science
After sunset, see the 5 planets in the sky or via video


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How to see 5 planets
This week (late March 2023), you can see five planets lined up in our evening sky: Venus and Uranus, Jupiter and Mercury and Mars. Gianluca Massi of the Virtual Telescope Project in Rome, Italy, showed them through a telescope earlier today (March 29). To enjoy his presentation, watch the video below. In addition, you can see them in the sky, perhaps, if your sky conditions are very good, and you have a sharp eye.
As soon as the sun sets, the planets are positioned in a gentle arc across the evening sky, following the sun’s path across our sky. Likewise, the Moon and the planets also follow the eclipse.
How can we see the planets? Go out around sunset and look west. Among them you can easily spot the bright planet Venus.
Then use binoculars to scan the planet Uranus next to Venus.
Then aim your binoculars low in the sky, near the point where the sun is setting. That is where you will find Jupiter and Mercury.
Then look high in the sky — still see the eclipse or the path of the Sun — to Mars.
Guide to Planetary Viewing
Venus and Uranus. Of these five planets, Venus is the brightest and Uranus is the dim. These two are close together in the sky. Venus is easily visible to the eye. It is the first “star” (actually, planet) to come into view. Uranus shines at +5.8 magnitudes. This is theoretically obvious. But, in practice, you need a dark sky and a telescope to find it. It was roughly 1.5 degrees or three moon widths from Venus earlier this week. Uranus will be closest to Venus on Thursday, March 30.
Thursday and Wednesday. Jupiter is the 2nd brightest planet. But it is now near sunset and visible only in bright twilight. Bright twilight skies make Jupiter more difficult to find. But Jupiter is still visible to the naked eye very close to sunset. And Wednesday? It is fainter than Jupiter (though still brighter than most stars). But it is near sunset. Shortly after sunset, start looking for the pair on the western horizon. You need clear skies and an unobstructed western view to catch them. A telescope should help. They disappear only 30 minutes after sunset. So, when the sun sets, the clock chimes.
tuesday, now the 5th planet in the evening sky, was easy to spot earlier this week because it’s not far from the Moon in our sky’s dome. A bright red light near the moon on Tuesday evening, March 28, 2023. Mars is bright. It is brighter than most stars. And it is clearly red. Even after the sun goes away, you can still spot Mars by its color and by the fact that it doesn’t shine like stars.
Some inventor charts
























Bottom line: You have a chance to see five planets tonight and throughout this week. Here are illustrations and information, including where to look in the video.
For more celestial events, visit EarthSky’s Night Sky Guide.





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