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Astronomers Have Found the Universe’s Missing Matter

Astronomers have finally found the last of the missing universe. It’s been hiding since the mid-1990s, when researchers decided to inventory all the “ordinary” matter in the cosmos—stars and planets and gas, anything made out of atomic parts. (This isn’t “dark matter,” which remains a wholly separate enigma.) They had a pretty good idea of how much should be out there, based on theoretical studies of how matter was created during the Big Bang. Studies of the cosmic microwave background (CMB)—the leftover light from the Big Bang—would confirm these initial estimates.

So they added up all the matter they could see—stars and gas clouds and the like, all the so-called baryons. They were able to account for only about 10 percent of what there should be. And when they considered that ordinary matter makes up only 15 percent of all matter in the universe—dark matter makes up the rest—they had only inventoried a mere 1.5 percent of all matter in the universe.

Now, in a series of three recent papers, astronomers have identified the final chunks of all the ordinary matter in the universe. (They are still deeply perplexed as to what makes up dark matter.) And despite the fact that it took so long to identify it all, researchers spotted it right where they had expected it to be all along: in extensive tendrils of hot gas that span the otherwise empty chasms between galaxies, more properly known as the warm-hot intergalactic medium, or WHIM.

Early indications that there might be extensive spans of effectively invisible gas between galaxies came from computer simulations done in 1998. “We wanted to see what was happening to all the gas in the universe,” said Jeremiah Ostriker, a cosmologist at Princeton University who constructed one of those simulations along with his colleague Renyue Cen. The two ran simulations of gas movements in the universe acted on by gravity, light, supernova explosions and all the forces that move matter in space. “We concluded that the gas will accumulate in filaments that should be detectable,” he said.

Except they weren’t — not yet.

“It was clear from the early days of cosmological simulations that many of the baryons would be in a hot, diffuse form — not in galaxies,” said Ian McCarthy, an astrophysicist at Liverpool John Moores University. Astronomers expected these hot baryons to conform to a cosmic superstructure, one made of invisible dark matter, that spanned the immense voids between galaxies. The gravitational force of the dark matter would pull gas toward it and heat the gas up to millions of degrees. Unfortunately, hot, diffuse gas is extremely difficult to find.

To spot the hidden filaments, two independent teams of researchers searched for precise distortions in the CMB, the afterglow of the Big Bang. As that light from the early universe streams across the cosmos, it can be affected by the regions that it’s passing through. In particular, the electrons in hot, ionized gas (such as the WHIM) should interact with photons from the CMB in a way that imparts some additional energy to those photons. The CMB’s spectrum should get distorted.

Unfortunately the best maps of the CMB (provided by the Planck satellite) showed no such distortions. Either the gas wasn’t there, or the effect was too subtle to show up.

But the two teams of researchers were determined to make them visible. From increasingly detailed computer simulations of the universe, they knew that gas should stretch between massive galaxies like cobwebs across a windowsill. Planck wasn’t able to see the gas between any single pair of galaxies. So the researchers figured out a way to multiply the faint signal by a million.

First, the scientists looked through catalogs of known galaxies to find appropriate galaxy pairs — galaxies that were sufficiently massive, and that were at the right distance apart, to produce a relatively thick cobweb of gas between them. Then the astrophysicists went back to the Planck data, identified where each pair of galaxies was located, and then essentially cut out that region of the sky using digital scissors. With over a million clippings in hand (in the case of the study led by Anna de Graaff, a Ph.D. student at the University of Edinburgh), they rotated each one and zoomed it in or out so that all the pairs of galaxies appeared to be in the same position. They then stacked a million galaxy pairs on top of one another. (A group led by Hideki Tanimura at the Institute of Space Astrophysics in Orsay, France, combined 260,000 pairs of galaxies.) At last, the individual threads — ghostly filaments of diffuse hot gas — suddenly became visible.

(A) Images of one million galaxy pairs were aligned and added together.
(B) Astronomers mapped all the gas within the actual galaxies.
(C) By subtracting the galaxies (B) from the initial image (A), researchers revealed filamentary gas hiding in intergalactic space.Adapted by Quanta Magazine

The technique has its pitfalls. The interpretation of the results, said Michael Shull, an astronomer at the University of Colorado at Boulder, requires assumptions about the temperature and spatial distribution of the hot gas. And because of the stacking of signals, “one always worries about ‘weak signals’ that are the result of combining large numbers of data,” he said. “As is sometimes found in opinion polls, one can get erroneous results when one has outliers or biases in the distribution that skew the statistics.”

In part because of these concerns, the cosmological community didn’t consider the case settled. What was needed was an independent way of measuring the hot gas. This summer, one arrived.

Lighthouse Effect

While the first two teams of researchers were stacking signals together, a third team followed a different approach. They observed a distant quasar — a bright beacon from billions of light-years away — and used it to detect gas in the seemingly empty intergalactic spaces through which the light traveled. It was like examining the beam of a faraway lighthouse in order to study the fog around it.

Usually when astronomers do this, they try to look for light that has been absorbed by atomic hydrogen, since it is the most abundant element in the universe. Unfortunately, this option was out. The WHIM is so hot that it ionizes hydrogen, stripping its single electron away. The result is a plasma of free protons and electrons that don’t absorb any light.

Fabrizio Nicastro used light from a quasar to track the missing gas.Courtesy of Fabrizio Nicastro

So the group decided to look for another element instead: oxygen. While there’s not nearly as much oxygen as hydrogen in the WHIM, atomic oxygen has eight electrons, as opposed to hydrogen’s one. The heat from the WHIM strips most of those electrons away, but not all. The team, led by Fabrizio Nicastro of the National Institute for Astrophysics in Rome, tracked the light that was absorbed by oxygen that had lost all but two of its electrons. They found two pockets of hot intergalactic gas. The oxygen “provides a tracer of the much larger reservoir of hydrogen and helium gas,” said Shull, who is a member of Nicastro’s team. The researchers then extrapolated the amount of gas they found between Earth and this particular quasar to the universe as a whole. The result suggested that they had located the missing 30 percent.

The number also agrees nicely with the findings from the CMB studies. “The groups are looking at different pieces of the same puzzle and are coming up with the same answer, which is reassuring, given the differences in their methods,” said Mike Boylan-Kolchin, an astronomer at the University of Texas, Austin.

The next step, said Shull, is to observe more quasars with next-generation X-ray and ultraviolet telescopes with greater sensitivity. “The quasar we observed was the best and brightest lighthouse that we could find. Other ones will be fainter, and the observations will take longer,” he said. But for now, the takeaway is clear. “We conclude that the missing baryons have been found,” their team wrote.

Read More On This At Science Latest

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Space

Von Braun Station: the first space hotel would be ready by 2025

Inspired by the concepts of a Nazi rocket scientist, Wernher von Braun, this station-hotel Von Braun Station will have its own gravity, kitchen, bars and interiors made with natural materials, and will be able to accommodate up to 400 people.

Von Braun Station

“The station could receive the first tourists in a few years,” said Tim Alatorre, senior architect of the Gateway Foundation , the company responsible for the station’s design.

“The goal of the Gateway Foundation is that in 2025 Von Braun already works and 100 tourists visit it per week,” he said.

According to the designer, the station, which will have the shape of a huge 190-meter diameter wheel, will turn constantly, creating an artificial gravitation comparable to that of the Moon and making the stay in it much more comfortable than in the ISS, where it is not possible to have a sense of direction.

The concept was taken from nothing less than Wernher von Braun, hence its name. This was a leading Nazi scientist who developed the V2 rocket. After World War II, NASA welcomed him to design, among other things, the Saturn V rocket that would take the human being to the Moon.

How will it be built?

The hotel station will be built by using automated systems, such as drones and robots, while in orbit. It will also use GSAL, special space construction machinery developed by Orbital Construction.

Once completed, some modules will be rented as individual residences, while others will be offered to different governments for scientific purposes. In total, the Gateway Foundation expects the population of the Von Braun wheel to be about 400 people.

In space … at home

Apart from rooms, the hotel part of the wheel will feature many of the things that are seen on cruises, such as restaurants, bars, music concerts, film screenings and educational seminars. Also, the interiors will have nothing to do with the sterility of the space stations of science fiction films.

«As humans, we are innately connected with natural materials and colors. […] The use of fabrics, lighting and warm-colored paints and textured materials help us connect and feel at home, ”said Alatorre, although he admitted that heavy materials, such as wood and stone, will be replaced by“ substitutes for light and easy to clean natural materials ».

The architect said that the project, which presupposes the creation of even larger space hotels, tries to put an end to the current high prices of orbital tourism, making it accessible to broad social sectors and facilitating extraterrestrial exploration.

” Gateway Foundation aims to make space travel open to everyone and this and the company’s next project will be true cities in space that will be ports of call for those who come and go from the Moon and Mars,” he concluded. .

Source: Dezeen

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Ariana Grande Responds to NASA Interns Remixing Her Song

It’s no secret that Ariana Grande is a fan of space and, by extension, the folks over at NASA. And it turns out that the love is reciprocal, seeing as how a group of interns at NASA’s Johnson Space Center have just given her song “NASA” the remix treatment.

An “educational parody” of Grande’s track, the interns created an accompanying video “in order to inform the public about the amazing work going on at NASA and thee Johnson Space Center,” per its description.

Even cooler? The specific project the interns that inspired the interns is NASA’s forthcoming Artemis missions, which aims to send the first woman to the moon by 2024.

Given all of this, Grande was obviously over-the-moon about the parody. No pun intended.

“Oh my. this is so pure and special and insane,” she tweeted in response. “hi everyone over there that is doing such incredible work ! thank u for taking the time to make this ! my heart is ….. bursting.”

Watch the entire remix video for yourself, below.

Source www.papermag.com

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Space

Another Interstellar Comet Has Arrived

“Based on the available observations, the orbit solution for this object has converged to the hyperbolic elements shown below, which would indicate an interstellar origin. A number of other orbit computers have reached similar conclusions, initially D. Farnocchia (JPL), W. Gray, and D. Tholen (UoH).”

Remember ‘Oumuamua, the first interstellar object ever discovered in our solar system? You won’t for long as another one was picked up by multiple observers and reported this week by The Minor Planet Center (MPC) at Harvard University. Unlike ‘Oumuamua, this one is definitely a comet and has been identified earlier enough in its trip through the solar system to be analyzed intensely – possibly revealing where it came from and how astronomers can locate more of them.

‘Oumuamua

“The comet’s current velocity is high, about 93,000 mph [150,000 kph], which is well above the typical velocities of objects orbiting the sun at that distance. The high velocity indicates not only that the object likely originated from outside our solar system, but also that it will leave and head back to interstellar space.”

The BBC reports that object gb00234, now known as Comet C/2019 Q4, was discovered by amateur (but experienced) astronomer Gennady Borisov on August 30th, 2019, at the Crimean Astrophysical Observatory in Bakhchysarai. When he noticed it, C/2019 Q4 was three astronomical units (450 million km) from the Sun. Since then, other astronomers have seen its tail – confirming C/2019 Q4 is a comet – and measured its eccentricity at 3.2, based on current observations. A perfect circle has an eccentricity of 0, while a closed elliptical orbit ranges from 0 to 1. Anything greater than one indicates an arc-shaped trajectory and is likely an interstellar comet or object making a one-time visit. While not confirmed yet, together these make Comet C/2019 Q4 the first ‘true’ comet to visit use from outside our solar system.

Unless it’s a spaceship.

Good point. Anyone?

Karl Battams
@SungrazerComets
Unlike ‘Oumuamua, whose asteroid-or-comet nature still gets debated, this one is definitely a comet. If it is unequivocally interstellar, it’ll be fascinating to see how its composition (spectral properties) compare to the variety we see in comets from our own solar system.

Astrophysicist Karl Battams, from the Naval Research Laboratory in Washington DC, tweeted an end to that comet-asteroid-spaceship-or-what debate which has trailed ‘Oumuamua like a tail (if it had one) since it was discovered hightailing out of here. Comet C/2019 Q4 will have plenty of eyes on it as it will be visible to even low-powered professional telescopes for at least a year, including when it makes its turn around the sun (perihelion) around December 10. However, the MPC leaves an opening for the unusual:

“Absent an unexpected fading or disintegration, [C/2019 Q4] should be observable for at least a year.”

In lieu of seeing windows with aliens waving out of them, an “unexpected disintegration” would be the next coolest thing.

Source: Mysterious Universe

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