#Epoch of the Cosmic Dawn --'Faint Signal of First Atoms Detected'

[spacenutspod]

Hydrogen is the most abundant element in the Universe. By far. More than 90% of the atoms in the Universe are hydrogen. Ten times the number of helium atoms, and a hundred times more than all other elements combined. It’s everywhere, from the water in our oceans to the earliest regions of the Cosmic Dawn. Fortunately for astronomers, all this neutral hydrogen can emit a faint emission line of radio light. It’s known as the H I hydrogen line, or the 21-centimeter line. Hydrogen consists of a single electron bound to a single proton. When the spins of these two are aligned in the same way, hydrogen has a slightly higher energy than when the spins are oppositely directed. So the electron can undergo a spin flip and release a bit of energy as a photon of light. The hydrogen doesn’t need to be superheated or ionized to do this. It can happen spontaneously. So wherever there are clouds of hydrogen, you can be sure it’s emitting 21-centimeter radio light. Spin-flip decay for neutral hydrogen. Credit: Wikipedia user Tiltec Since the emission line has a very specific wavelength, we can use it to measure the relative motion or cosmological redshift of hydrogen. One of the first uses of this trick was to measure the motion of hydrogen in the Milky Way and other nearby galaxies, which allowed Vera Rubin to discover dark matter. Now a new study shows how the 21-centimeter line might give us the first evidence of dark matter particles. The study focuses on the Hydrogen Epoch of Reionization Array (HERA), which is a radio telescope in South Africa particularly suited for observing hydrogen in the early Universe. When it comes online, HERA will map the large-scale structure of hydrogen during the cosmic dark ages and cosmic dawn period, which is the time between the fading of the primeval fireball of the Big Bang and the appearance of the first stars and galaxies. During this period the cosmos was filled with dark matter and warm clouds of hydrogen gas. How WIMPs might decay. Credit: GAO Linqing and LIN Sujie If dark matter is truly neutral, and only interacts with matter and light gravitationally, then the 21-centimeter light is basically the only light emitted during this period. But the most popular model for dark matter involves particles known as WIMPs. Neutral dark matter particles are much heavier than regular matter particles such as protons and electrons. In some dark matter particles, these WIMPs occasionally decay into regular matter, creating a burst of energetic positrons and electrons, or protons and anti-protons. If that’s the case, then these energetic decay particles would interact with the 21-centimeter light. HERA would further constrain dark matter lifetimes. Credit: Facchinetti, et al Based on observations of the cosmic microwave background and other studies, we know that WIMPs would have a very long decay half-life. We’ve seen no evidence of dark matter decay so far, which means either WIMPs don’t exist or their half-life is much more than a trillion years. This new study shows that even if WIMPs had a half-life a thousand times longer, HERA would be able to detect its effect on the early 21-centimeter line. And it would have enough data to do that within 1,000 hours of observation. Even if HERA doesn’t detect any evidence of dark matter decay, it would still be a large step forward. Its constraints on dark matter half-life would be strong enough to rule out some WIMP models and winnow the range of models. Reference: Facchinetti, Gaétan, et al. “21cm signal sensitivity to dark matter decay.” arXiv preprint arXiv:2308.16656 (2023). The post A New Telescope Could Detect Decaying Dark Matter in the Early Universe appeared first on Universe Today.

[entertainmentnerdly]

Epoch of the Cosmic Dawn --'Faint Signal of First Atoms Detected' via /r/space https://ift.tt/3EDMcDR

[spacetimewithstuartgary]

SCIENTISTS CLOSE INCH CLOSER THAN EVER TO SIGNAL FROM COSMIC DAWN Around 12 billion years ago, the universe emerged from a great cosmic dark age as the first stars and galaxies lit up. With a new analysis of data collected by the Murchison Widefield Array (MWA) radio telescope, scientists are now closer than ever to detecting the ultra-faint signature of this turning point in cosmic history. In a paper on the preprint site ArXiv and soon to be published in The Astrophysical Journal, researchers present the first analysis of data from a new configuration of the MWA designed specifically to look for the signal of neutral hydrogen, the gas that dominated the universe during the cosmic dark age. The analysis sets a new limit -- the lowest limit yet -- for the strength of the neutral hydrogen signal. “We can say with confidence that if the neutral hydrogen signal was any stronger than the limit we set in the paper, then the telescope would have detected it,” said Jonathan Pober, an assistant professor of physics at Brown University and corresponding author on the new paper. “These findings can help us to further constrain the timing of when the cosmic dark ages ended and the first stars emerged.” The research was led by Wenyang Li, who performed the work as a Ph.D. student at Brown. Li and Pober collaborated with an international group of researchers working with the MWA. Despite its importance in cosmic history, little is known about the period when the first stars formed, which is known as the Epoch of Reionization (EoR). The first atoms that formed after the Big Bang were positively charged hydrogen ions -- atoms whose electrons were stripped away by the energy of the infant universe. As the universe cooled and expanded, hydrogen atoms reunited with their electrons to form neutral hydrogen. And that’s just about all there was in the universe until about 12 billion years ago, when atoms started clumping together to form stars and galaxies. Light from those objects re-ionized the neutral hydrogen, causing it to largely disappear from interstellar space. The goal of projects like the one happening at MWA is to locate the signal of neutral hydrogen from the dark ages and measure how it changed as the EoR unfolded. Doing so could reveal new and critical information about the first stars -- the building blocks of the universe we see today. But catching any glimpse of that 12-billion-year-old signal is a difficult task that requires instruments with exquisite sensitivity. When it began operating in 2013, the MWA was an array of 2,048 radio antennas arranged across the remote countryside of Western Australia. The antennas are bundled together into 128 “tiles,” whose signals are combined by a supercomputer called the Correlator. In 2016, the number of tiles was doubled to 256, and their configuration across the landscape was altered to improve their sensitivity to the neutral hydrogen signal. This new paper is the first analysis of data from the expanded array. Neutral hydrogen emits radiation at a wavelength of 21 centimeters. As the universe has expanded over the past 12 billion years, the signal from the EoR is now stretched to about 2 meters, and that’s what MWA astronomers are looking for. The problem is there are myriad other sources that emit at the same wavelength -- human-made sources like digital television as well as natural sources from within the Milky Way and from millions of other galaxies. “All of these other sources are many orders of magnitude stronger than the signal we’re trying to detect,” Pober said. “Even an FM radio signal that’s reflected off an airplane that happens to be passing above the telescope is enough to contaminate the data.” To home in on the signal, the researchers use a myriad of processing techniques to weed out those contaminants. At the same time, they account for the unique frequency responses of the telescope itself. “If we look at different radio frequencies or wavelengths, the telescope behaves a little differently,” Pober said. “Correcting for the telescope response is absolutely critical for then doing the separation of astrophysical contaminants and the signal of interest.” Those data analysis techniques combined with the expanded capacity of the telescope itself resulted in a new upper bound of the EoR signal strength. It’s the second consecutive best-limit-to-date analysis to be released by MWA and raises hope that the experiment will one day detect the elusive EoR signal. “This analysis demonstrates that the phase two upgrade had a lot of its desired effects and that the new analysis techniques will improve future analyses,” Pober said. “The fact that MWA has now published back-to-back the two best limits on the signal gives momentum to the idea that this experiment and its approach has a lot of promise.”

[shirlleycoyle]

Scientists Are Chasing an Ancient Signal That Could Explain the Modern Universe

All around the world, radio antennae in remote landscapes are scanning the sky for the same faint signal from the “cosmic dawn,” a time when the first stars shone more than 12 billion years ago.

If detected, the signal will shed light on some of the most enduring mysteries about the origins of, well, everything—stars, galaxies, even the enigmatic dark matter and dark energy that scientists think makes up 95 percent of the universe’s mass. In fact, the discovery would be so significant that at least one of the many teams hunting for the signal thinks it would be a likely candidate for the Nobel Prize.

“There is a lot of competition about who will be there first, but on the other hand, there is also collaboration and knowledge that is shared,” said Anastasia Fialkov, a senior research fellow at the Kavli Institute for Cosmology in Cambridge, UK, in a call.

Slowly but surely, scientists are closing in on this momentous detection. In September, a team published a new timeframe of the era from which the signal originates that is about 10 times more precise than previous estimates. Last year, another team captured the most promising potential detection of the signal so far, though those results are still under review.

The signal is not a message from an alien civilization, or a glimpse of some exotic object at the edge of time. In fact, it comes from one of the universe’s simplest components: neutral hydrogen atoms. Because these atoms absorb and release photons with wavelengths of 21 centimeters, the signal is known alternately as the neutral hydrogen signal or the 21-centimeter signal.

The signature of this ancient hydrogen could open up the first observational window into the early Epoch of Reionization (EoR). This is the murkiest era of the universe’s history, and began a few hundred million years after the Big Bang.

“We know that neutral hydrogen is there, so the neutral hydrogen signal must also be there,” explained Leon Koopmans, a professor at the University of Groningen and principal investigator of the LOFAR Epoch of Reionization Key Science Project, which uses the LOFAR telescope to hunt for the neutral hydrogen signal.

Before the EoR, the universe was bereft of starlight, in a time known as the cosmic Dark Ages. After the EoR, the basic structure of the known universe we inhabit today, speckled with stars and galaxies and sculpted by dark matter and energy, had materialized. But scientists know next to nothing about the roughly 500-million-year stretch that separates the Dark Ages from the modern, light-filled universe.

The best bet for finally probing this inaccessible era is to capture that neutral hydrogen signal.

But detecting it has proved to be one of the most difficult pursuits in astronomy and cosmology. The 21-centimeter signal was already weak when it was created at cosmic dawn. After traversing extreme distances and timescales to reach us, the tiny signal is all but drowned out by louder interference from galaxies, stars, nebulae, and radio-emitting gadgets on Earth.

The signal is up to a million times fainter than all of this nearby radio noise, according to Koopmans.

“All the energy ever collected by a radio telescope, such as LOFAR, does not exceed that of a snowflake falling on Earth,” he said. “The energy emitted by the neutral hydrogen signal is still 100,000 less than that.”

The signal that could illuminate everything

For the first billion years of its life, the universe was drastically different from the place we live in today. In the aftermath of the Big Bang, it was so hot and energetic that protons and electrons were not able to combine to form stable neutral atoms, so the universe was basically a super-heated soup of opaque subatomic particles.

Cosmic conditions had cooled down by about 378,000 years after the Big Bang, enabling the formation of neutral hydrogen and ushering in what is called the Era of Recombination. When atoms started to form during this period, the universe became more transparent, enabling light to freely travel without being scattered by random subatomic particles. This radiation, called the cosmic microwave background, is the oldest light ever detected in the universe.

As the universe transitioned from hot plasma to cold condensing gas, it plunged into the cosmic Dark Ages. Scientists think there are only two observable forms of light from this time: the cosmic microwave background and the much sought-after 21-centimeter signal.

“When you tune your car radio between stations on the FM dial, 99.7% of the static you hear is radio noise from relativistic electrons spiraling around magnetic fields in our galaxy and other nearby galaxies, 0.3% is from the afterglow of the Big Bang, and only 0.01% is from the 21-centimeter signal,” said Judd Bowman, an experimental cosmologist at Arizona State University, in an email.

The signal was originally created when electrons in neutral hydrogen atoms changed energy states, before and during the EoR. Photons absorbed or released by these tiny electron shifts initially had the characteristic 21-centimeter wavelength, but the expansion of the universe is expected to have elongated them to anywhere from two and 20 meters by the time they reach Earth.

Once the first stars began to shine, flooding the universe with much more energetic radiation, the neutral hydrogen atoms gradually became ionized, which means they were stripped of electrons. This marked the beginning of the Epoch of Reionization, when the light from stars and galaxies converted much of the universe’s neutral hydrogen into ionized hydrogen. Most of the hydrogen in the universe remains ionized to this day.

As light from these luminous sources sprang forth and neutral hydrogen diminished as it became ionized, the signal weakened over the course of the EoR.

“The signal is sensitive to the light that the very first generation of stars would have produced,” Fialkov explained. “We can learn about the process of reionization from it: how efficient the first galaxies were at ionizing the gas and how this efficiency varies with the mass of galaxies and halos in which they sit.”

The process of reionization played out over the course of several hundred million years, but was completed by the time the universe reached its one billionth birthday. Because the universe was engulfed in darkness before reionization, it is challenging to detect anything from the early part of the EoR that could provide clues about the structure of the universe at that time.

Scientists have managed to spot some of the oldest stars and galaxies in the universe, but it is not yet possible to glimpse these radiant objects at cosmic dawn. That’s why neutral hydrogen is such a valuable means of indirectly detecting the first generation of stars and galaxies—provided scientists can capture it.

“One of the highest priorities in astrophysics is to understand the properties and evolution of the first stars and galaxies,” Bowman said. “These are the objects that transformed the early universe, altering nearly every atom with their radiation and seeding the universe with the elements that would ultimately make up the Earth and all of us.”

The planet-wide race to detect the 21-centimeter signal

The notion that the neutral hydrogen signal could be used to study some of the earliest days of the universe has been around for decades, but it is only within the past 10 years or so that technology has started to catch up to that vision.

LOFAR, which was completed in 2012, has an enormous collecting area with small antennae spanning the Netherlands, Germany, the United Kingdom, France, Sweden, and Ireland. This huge geographic range allows the team to hone in on the signal by correcting for errors in the instrument or perturbations in Earth’s atmosphere, Koopmans said.

The Murchison Widefield Array (MWA), also completed in 2012, is smaller than LOFAR, but has the benefit of low radio interference due to its remote location in the Western Australian outback. The Experiment to Detect the Global EoR Signature (EDGES), an instrument run by the MWA, has already produced “the most promising evidence for a 21-centimeter detection so far,” said Bowman, who led the research, which was published in a 2018 Nature paper.

The team is now waiting for other measurements to confirm their findings, Bowman said. The need for verification is especially relevant to the 2018 study because it was full of surprises that challenge existing models of the early universe. The discrepancies between the predicted signal and what was actually detected suggest that “either the primordial gas was much colder than expected or the background radiation temperature was hotter than expected,” Bowman’s team said in the study.

“We don’t know how to explain it with the standard astrophysics that we know and love,” said Fialkov. “Exotic models have to be added to explain it and it still doesn’t look natural.”

Some of those models suggest that dark matter may have been responsible for the colder-than-expected temperatures detected at the break of cosmic dawn. “We’ve learned from the explanations proposed for the depth of the EDGES profile that cosmic dawn may hold the secret to unlocking the nature of dark matter,” said Bowman.

The allure of such a cosmological treasure trove has motivated teams to build observatories to search for the neutral hydrogen signal in the Northern Cape of South Africa, the mountains of Tibet, and Antarctica, among other sites. There are even a few proposals to launch space observatories to hunt for even older signals, either from orbit or on the far side of the Moon.

“Signals from the Dark Ages, which precedes formation of first stars, would be really interesting to observe, but those signals cannot be observed from the ground because they are blocked by the ionosphere,” Fialkov said, referring to a layer of Earth’s atmosphere. “It acts as a mirror to the signals coming from space and they don’t penetrate and cannot be observed from Earth.”

“So going to space would open up this observational regime, and of course, going behind the Moon would also allow us to avoid radio frequency interference,” she added.

For now, the race for the first detection of neutral hydrogen continues planetside, as teams around the world scan the skies for this ancient relic using hyper-precise radio arrays. A few more tools are set to join the search, too.

EDGES-3, a next-generation version of the MWA instrument that detected the best signal candidate, is expected to be operational in 2020, according to Bowman. Another specialized telescope called the Hydrogen Epoch of Reionization Array (HERA), based in South Africa, is poised to collect data, and the Owens Valley Long Wavelength Array in California will also start hunting for the signal soon.

Bowman said that he is hopeful one of these projects will detect the signal within the next few years. “We have learned so much about how to make these measurements,” he said. “Now, it is a matter of putting the lessons learned into practice.”

Along the same lines, observatories such as MWA, LOFAR, or South Africa’s MeerKAT are also helping to inform the construction of the mother of all radio telescopes—the Square Kilometre Array (SKA).

This facility will consist of millions of radio antennae in South Africa and Australia that will form an intercontinental observatory that is 50 times more sensitive of any modern observatory. It is currently on track to be operational sometime in the late 2020s, and one of its biggest missions is probing the EoR.

“I think a detection itself will already be wonderful, on par with the detection of the cosmic microwave background (in fact more difficult!),” Koopmans said. “The wonderful thing with nature is that it always surprises us!”

Regardless of which team is the first to claim that milestone detection, this growing army of radio observatories will collaboratively build the broader picture of the universe’s transition from the dark ages to the modern era of starlight.

“I’m surprised and amazed at what we can do from the ground,” Fialkov said. “We are confined on Earth, but we can still look way back and understand how the very first stars formed.”

Scientists Are Chasing an Ancient Signal That Could Explain the Modern Universe syndicated from https://triviaqaweb.wordpress.com/feed/

[usviraltrends-blog]

New Post has been published on https://usviraltrends.com/signal-from-age-of-the-first-stars-could-shake-up-search-for-dark-matter-science-2/

Signal from age of the first stars could shake up search for dark matter | Science

In the Australian outback, small radio antennas were used to detect a 13.6-billion-year-old signal.

COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION

By Adrian ChoFeb. 28, 2018 , 1:00 PM

Using radio antennas the size of coffee tables, a small team of astronomers has glimpsed the cosmic dawn, the moment billions of years ago when the universe’s first stars began to shine. The observation also serves up surprising evidence that particles of dark matter—the unseen stuff that makes up most of the universe’s matter—may be much lighter than physicists thought.

If it holds up, the result could sharpen cosmologists’ picture of the early universe and shake up the search for dark matter. “It’s going to generate a huge amount of interest,” says Kevork Abazajian, a theoretical cosmologist at the University of California (UC), Irvine. But others worry that the subtle radio signal reported by the team could be an artifact. “I don’t think that right now, at least in my mind, it’s a clear discovery,” says Aaron Parsons, an experimental cosmologist at UC Berkeley.

The data come from the Experiment to Detect the Global Epoch of Reionization Signature (EDGES), a $2 million array of three radio antennas in the outback of Western Australia. The five EDGES researchers searched for signs that the hydrogen atoms that pervaded the newborn universe had absorbed microwaves lingering from the big bang.

The absorption marks the moment just after the first stars began to shine. Before that moment, the atoms’ internal states were in equilibrium with the microwaves, emitting as much radiation as they absorbed. But light from the first stars jostled the atoms’ innards, disrupting the equilibrium and enabling the atoms to absorb more of the microwaves than they emit.

The expansion of the universe stretches the absorption signal from its original 21-centimeter wavelength to longer radio wavelengths. However, radio noise from our galaxy is 30,000 times more intense. To subtract it, EDGES researchers relied on the noise’s smooth, precisely predictable spectrum. This week in Nature, they report detecting the tiny absorption signal—the cumulative shadows, they conclude, of hydrogen clouds that existed between 180 million and 250 million years after the big bang.

It’s the first thing scientists have seen in the time between the cosmic microwave background, 380,000 years after the big bang, and the oldest known galaxy, which shone 400 million years later, says EDGES leader Judd Bowman. “This is really the only possible probe that we have of the time before the stars,” says Bowman, who is an experimental astrophysicist at Arizona State University in Tempe. Ultimately, scientists hope to use the absorption signal or the fainter emission of 21-centimeter radiation from gas clouds at slightly later times to map the 3D distribution of hydrogen during these so-called cosmic dark ages, tracing its evolution into embryonic galaxies.

The absorption is more than twice as strong as predicted, which suggests that the hydrogen was significantly colder than previously thought. The gas must have lost heat to something even colder, and the only colder thing around was dark matter, which was coalescing into the clumps that would seed the formation of galaxies, reasons Rennan Barkana, an astrophysicist at Tel Aviv University in Israel. In a second paper in Nature, Barkana argues that to cool the hydrogen, the dark matter particles must have been less than five times as massive as a hydrogen atom. Otherwise the atoms would have bounced off them without losing energy and getting colder, just as a Ping-Pong ball will bounce off a bowling ball without slowing down.

Many dark matter searches have targeted hypothetical weakly interacting massive particles, which are generally expected to weigh hundreds of times as much as a hydrogen atom. As those searches have come up empty, some physicists have begun searching for lighter dark matter particles. The new result may encourage them, Abazajian says.

However, it’s too early to rule out a more mundane explanation for the unexpectedly strong absorption, cautions Katherine Freese, an astrophysicist at the University of Michigan in Ann Arbor. “Is [this scenario] the only way to explain this? Of course not.”

A more pressing question is whether the signal is an experimental artifact, Parsons says. The measurements rely on calibrations that could produce false signals if they are off by just a few hundredths of a percent, he says. Bowman says he and his colleagues “have gone as far as we can go to ensure that there isn’t an error, but, of course, we’re eager for others to confirm the result.”

Confirmation could come from other experiments that are probing the dark ages. Parsons leads one, called the Hydrogen Epoch of Reionization Array in South Africa, which is trying not just to detect the faint signals, but to map them across the sky. They may soon show whether cosmic dawn has really broken.

[spacetimewithstuartgary]

ALMA FINDS OXYGEN 13.28 BILLION LIGHT-YEARS AWAY: MOST DISTANT OXYGEN INDICATES MATURE NATURE OF A YOUNG GALAXY Astronomers detected a faint but definite signal of oxygen in a galaxy located 13.28 billion light-years away from us, through observations using the Atacama Large Millimeter/submillimeter Array (ALMA). Breaking their own records, this marks the most distant oxygen ever detected in the universe. Referencing infrared observations, the team determined that star formation in the galaxy started at an unexpectedly early stage; 250 million years after the Big Bang. “Rather than saying I was happy, it would be more accurate to say I was thrilled to see the signal of the most distant oxygen,” explains Takuya Hashimoto, the lead author of the research paper published in the journal Nature and a researcher at Osaka Sangyo University and the National Astronomical Observatory of Japan. “I was excited enough that the signal appeared in my dreams and I had difficulty sleeping that night.” An international team of astronomers led by Hashimoto used ALMA to observe a distant galaxy called MACS1149-JD1. They detected a signal from ionized oxygen in the galaxy. The infrared light emitted from oxygen was stretched to microwave wavelengths by the expansion of the universe before it reached Earth and was observed by ALMA. The team measured the change in the wavelength of the light and found that the signal had traveled 13.28 billion light-years [1] to reach us, making it the most distant, or oldest, oxygen ever detected by any telescope. In addition, a weaker signal of neutral hydrogen emissions was independently found with the European Southern Observatory’s Very Large Telescope; the distance determined from this observation is consistent with the distance based on the oxygen observation. MACS1149-JD1 is the most distant galaxy with a precise distance measurement [2]. For a certain period after the Big Bang, there was no oxygen in the universe. Oxygen was created in stars and then released when the stars died. The detection of oxygen in MACS1149-JD1 indicates that an earlier generations of stars had been already formed and expelled processed oxygen by the epoch of observation, which is only about 500 million years after the beginning of the universe. The team then reconstructed the star formation history in the galaxy using infrared data taken with the NASA/ESA Hubble Space Telescope and NASA Spitzer Space Telescope. The observed brightness of the galaxy is well explained by a model where the onset of star formation was another 250 million years ago. The model indicates that the star formation became inactive once after the first ignition, and then revived at the epoch of the ALMA observations; 500 million years after the Big Bang. The astronomers suppose that the first star formation burst blew the gas away from the galaxy, which would suppress the star formation. Then, the gas returned to the galaxy leading to the second burst of star formation. The massive newborn stars in the second burst ionize oxygen, and it’s those emissions that have been detected with ALMA. “The mature stellar population in MACS1149-JD1 implies that stars were forming back to even earlier times, beyond what we can currently see with our telescopes. This has very exciting implications for finding ‘cosmic dawn’ when the first galaxies emerged” adds Nicolas Laporte, a researcher at University College London and a member of the research team. ALMA has set the record for the most distant oxygen several times. In 2016, Akio Inoue at Osaka Sangyo University and his colleagues found the signal of oxygen at 13.1 billion light-years away with ALMA [3]. Several months later, Nicolas Laporte of University College London used ALMA to detect oxygen at 13.2 billion light-years away [4]. Now, the two teams merged into one and achieved this new record. “This reflects the both competitive and collaborative nature of the forefront of scientific research,” said Inoue. “With this discovery we managed to reach the earliest phase of cosmic star formation history,” said Hashimoto. “We are eager to find oxygen in even farther parts of the universe and expand the horizon of human knowledge.” Notes [1] The measured redshift of galaxy MACS1149-JD1 is z = 9.11. A calculation based on the latest cosmological parameters measured with Planck (H_0 = 67.3 km/s/Mpc, Omega_m = 0.315, Lambda = 0.685: Planck 2013 Results) yields the distance of 13.28 billion light-years. Please refer to “Expressing the distance to remote objects” [https://www.nao.ac.jp/en/astro/glossary/expressing-distance.html] for the details. [2] The galaxy GN-z11 is thought to be located 13.4 billion light-years away based on observations with the Hubble Space Telescope (HST). But the precision of the distance measurement with HST low resolution spectroscopy is significantly lower than that of ALMA’s measurement using a single emission line from atoms. [3] See details in the ALMA press release “ALMA Detected the Most Distant Oxygen” [https://alma-telescope.jp/en/news/mt-alma_detected_the_most_distant_oxygen] in June 2016. [4] See details in the ALMA press release “Ancient Stardust Sheds Light on the First Stars -- Most distant object ever observed by ALMA” [https://alma-telescope.jp/en/news/mt-ancient_stardust_sheds_light_on_the_first_starsmost_distant_object_ever_observed_by_alma] in March 2017. TOP IMAGE....This image shows the galaxy cluster MACS J1149.5+2223 taken with the NASA/ESA Hubble Space Telescope and the inset image is the galaxy MACS1149-JD1 located 13.28 billion light-years away observed with ALMA. Here, the oxygen distribution detected with ALMA is depicted in green. Credit: ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope, W. Zheng (JHU), M. Postman (STScI), the CLASH Team, Hashimoto et al. LOWER IMAGE....Microwave spectrum of oxygen ions in MACS1149-JD1 detected with ALMA. It was originally infrared light with a wavelength of 88 micrometers, and ALMA detected it as microwaves with an increased wavelength of 893 micrometers due to the expansion of the Universe. Credit: ALMA (ESO/NAOJ/NRAO), Hashimoto et al.