martes, 30 de junio de 2020

A Tale of Two Telescopes: WFIRST and Hubble | NASA

A Tale of Two Telescopes: WFIRST and Hubble | NASA



Hubble Ultra Deep Field image

A Tale of Two Telescopes: 

WFIRST and Hubble

NASA’s Wide Field Infrared Survey Telescope (WFIRST), planned for launch in the mid-2020s, will create enormous cosmic panoramas. Using them, astronomers will explore everything from our solar system to the edge of the observable universe, including planets throughout our galaxy and the nature of dark energy.
Though it’s often compared to the Hubble Space Telescope, which turns 30 years old this week, WFIRST will study the cosmos in a unique and complementary way.
“WFIRST will enable incredible scientific progress on a broad range of topics, from stellar populations and distant planets to dark energy and the structure of galaxies,” said Ken Carpenter, the WFIRST ground system project scientist and Hubble operations project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Hubble contributed tremendously to our understanding in these areas, but WFIRST will propel us forward by studying far more objects in the sky.”
Thirty years after its launch, Hubble continues to provide us with stunning, detailed images of the universe. When WFIRST opens its eyes to the cosmos, it will generate much larger images while matching Hubble’s crisp infrared resolution.
Hubble WFIRST Webb Infographic
This infographic shows the complementary capabilities of select instruments on three of NASA's flagship missions: the Hubble Space Telescope and the currently under development Wide Field Infrared Survey Telescope (WFIRST) and James Webb Space Telescope. Hubble views the cosmos in infrared, visible and ultraviolet light, providing a more comprehensive, high-resolution view of individual objects. WFIRST will expand on Hubble’s infrared observations specifically, using a much larger field of view to create enormous panoramas of the universe with the same high resolution. Webb will also conduct high-resolution infrared observations, peering across farther stretches of space with a narrower field of view.
Credits: NASA's Goddard Space Flight Center
Hubble adds to our picture of the universe in ways WFIRST can’t by using ultraviolet vision that captures the high-resolution details, and by providing more specialized features for in-depth study of the light emitted by individual objects. WFIRST provides a more general capability in covering wide areas at visible and infrared wavelengths. 
Each WFIRST image will capture a patch of the sky bigger than the apparent size of a full Moon. Hubble’s widest exposures, taken with its Advanced Camera for Surveys, are nearly 100 times smaller. Over the first five years of observations, WFIRST will image over 50 times as much sky as Hubble has covered so far in 30 years.​
Since the quality will be the same, WFIRST will function like a fleet of 100 Hubbles operating in sync. Its large field of view will enable WFIRST to conduct sweeping cosmic surveys that would take hundreds of years using Hubble. Scientists will use these surveys to study some of the most compelling mysteries in the universe, including dark energy — a strange force that is accelerating the expansion of the universe.
Hubble played a major role in discovering dark energy. In 1998, astronomers measured how fast the universe is expanding by using ground-based telescopes to study relatively nearby exploding stars, called supernovae. They made the surprising discovery that the expansion of the universe is speeding up. Astronomers using Hubble confirmed this result by measuring supernovae over a longer period of time. The data demonstrated that while the expansion of the universe was slowing down as expected over most of cosmic history, it began speeding up a few billion years ago.
Scientists have since determined that whatever is causing this acceleration currently makes up about 68% of the total matter and energy in the universe, but so far we don’t know much more about it. Uncovering the nature and role of dark energy will be one of WFIRST’s primary goals. Scientists will use three surveys to examine the dark energy puzzle from different angles, including a survey of one key type of supernova, building on the observations that led to dark energy’s discovery. The mission’s two large area surveys will measure the shapes of hundreds of millions of galaxies and find the distances to tens of millions. This will turn WFIRST’s wide-field images into 3D maps that measure the expansion of the universe and the growth of galaxies within it.
WFIRST will help us understand how dark energy has affected the expansion of the universe in the past, which will shed light on how it may influence the future of the cosmos.

A new set of eyes on the universe

While Hubble views the cosmos in infrared, visible and ultraviolet light, WFIRST will be tuned to see a slightly wider range of infrared light than Hubble can observe. Detecting more of the spectrum of light allows Hubble to create a more comprehensive picture of many processes at work in individual objects in the cosmos. WFIRST is designed to expand on Hubble’s infrared observations specifically, because conducting enormous surveys of the infrared universe will let us see vast numbers of cosmic objects and subtler processes in regions of space that would otherwise be difficult or impossible to view.
WFIRST will help unravel mysteries surrounding dark energy and the evolution of galaxies by peering across enormous stretches of the universe — even farther than Hubble is capable of seeing. These studies require precise infrared observations because light shifts into longer wavelengths, from ultraviolet and visible into infrared, as it travels across vast astronomical distances due to the expansion of space.
WFIRST’s infrared capabilities will also provide a new view into objects that are closer to home. The heart of our Milky Way galaxy is densely populated with rich targets, but shrouded in dust that obscures visible light. As an infrared telescope, WFIRST will essentially use heat-vision goggles to peer right through the dust, giving us a new view into the inner workings of the galaxy.
These observations will allow astronomers to study stellar evolution — the births, lives and deaths of stars. WFIRST will also expand our inventory of exoplanets — planets outside our solar system — by revealing thousands of worlds that astronomers expect will be very different from most of the 4,100 now known. Most of the currently known exoplanets are either very close to their host stars, or large planets orbiting farther away. Hubble has observed some of these planets directly using coronagraphs, which block the glare from stars. WFIRST will build upon that technology to make an active coronagraph that is much better at suppressing starlight — a demonstration of technology that, when further advanced, will enable future space telescopes to image Earth-size exoplanets.

Homing in on cosmic rarities

Scientists will also use WFIRST’s cosmic surveys to obtain enormous samples of some of the most extreme objects in the universe, including quasars — active galaxies with super-bright centers. Pinpointing their locations will allow Hubble and other telescopes to follow up for detailed observations. These investigations will enable astronomers to piece together the history of galaxy growth and the evolution of the universe.
To make these studies possible, WFIRST will operate much farther away from Earth than Hubble does. While Hubble orbits about 340 miles above us, WFIRST will be located about 930,000 miles (1.5 million km) away from Earth in the direction opposite the Sun. At this special place in space, called the second Sun-Earth Lagrange point, or L2, gravitational forces from the Sun and Earth balance to keep spacecraft in relatively stable orbits.
Near L2, WFIRST will orbit the Sun in sync with Earth, using a sunshield to block sunlight and keep the spacecraft cool. Since infrared light is heat radiation, if WFIRST is warmed by radiation from Earth, the Sun or even its own instruments, it will overwhelm the infrared sensors. From this vantage point, WFIRST can view large swaths of sky smoothly over long periods of time.

Enormous tapestries

Simulated WFIRST Observation of M31
This image, comparing the apparent sizes of the Andromeda galaxy and the Moon in the sky, demonstrates the type of observation WFIRST will produce. It took Hubble more than 650 hours between 2010 and 2013 to produce the portion of the image outlined in teal, but calculations suggest WFIRST could observe the same area in three hours or less. WFIRST’s infrared observations will also allow us to see through obscuring dust to help us gain further insights into the natures of planets, stars and galaxies.
Credits: Background image: Digitized Sky Survey and R. Gendler; Moon image: NASA, GSFC and Arizona State University; WFIRST simulation: NASA, STScI and B. F. Williams (University of Washington)
To collect as much light as possible, telescopes need large primary mirrors. Since both WFIRST and Hubble have a primary mirror that is 2.4 meters (7.9 feet) across, they gather the same amount of light. While the same size, WFIRST’s mirror is only one-fourth the weight of Hubble’s thanks to advancements in technology.
With Hubble’s similar light collection, resolution and an overlap in infrared capabilities, it can help set expectations for WFIRST. For example, Hubble produced a panoramic image of our neighboring Andromeda galaxy as part of the Panchromatic Hubble Andromeda Treasury (PHAT) program. Scientists compiled the PHAT image from 7,398 exposures taken over the course of three years. WFIRST could replicate Hubble’s PHAT image more than 1,000 times faster. This type of observation will reveal how stars change with time and influence the galaxy in which they reside.
Like Hubble, WFIRST will also offer a General Observer program to support the astronomical community, allowing scientists to take advantage of the mission’s unique capabilities by proposing new, competitively selected observations. As with Hubble, the pursuit of investigations not even contemplated before launch will likely become the primary legacy of the WFIRST mission. The entire trove of WFIRST data will be publicly available within days of being taken — a first for a NASA astrophysics flagship mission. WFIRST will have a robust archival research program to allow scientists to take full advantage of these vast datasets.
WFIRST benefits from an additional 30 years of major technological advances, however Hubble will continue to transform our understanding of the universe. In the coming years, WFIRST’s enormous infrared surveys will reveal interesting targets for follow up by other missions. Hubble can view the targets in additional wavelengths of light and will provide the only high-resolution view of the ultraviolet universe. The James Webb Space Telescope can make detailed observations that go even further into the infrared with its high-resolution, zoomed in view. Combining the WFIRST’s findings with Hubble’s and Webb’s could revolutionize our understanding in a multitude of cosmic pursuits.
“WFIRST’s surveys don’t require that we know exactly where and when to look to make exciting discoveries — we won’t be limited to looking under the cosmic lamppost,” said Goddard’s Julie McEnery, the WFIRST deputy project scientist. “The mission will turn on the floodlights so we can explore the universe in a whole new way.”
WFIRST is managed at Goddard, with participation by NASA's Jet Propulsion Laboratory and Caltech/IPAC in Pasadena, the Space Telescope Science Institute in Baltimore, and a science team comprising scientists from research institutions across the United States.
Banner: This famous Hubble Ultra Deep Field image captured the cosmos in three different types of light: infrared, visible and ultraviolet. While WFIRST will be tuned to see infrared light exclusively, its much wider field of view will enable larger surveys that would take hundreds or even thousands of years for Hubble to complete. Credit: NASA, ESA, H. Teplitz, M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University) and Z. Levay (STScI)

Media contact:
Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, Md.
301-286-1940
Last Updated: April 20, 2020
Editor: Ashley Balzer

Hubble Detects Smallest Known Dark Matter Clumps | NASA

Hubble Detects Smallest Known Dark Matter Clumps | NASA



Hubble Detects Smallest 

Known Dark Matter Clumps

Using NASA's Hubble Space Telescope and a new observing technique, astronomers have found that dark matter forms much smaller clumps than previously known. This result confirms one of the fundamental predictions of the widely accepted "cold dark matter" theory.
All galaxies, according to this theory, form and are embedded within clouds of dark matter. Dark matter itself consists of slow-moving, or “cold,” particles that come together to form structures ranging from hundreds of thousands of times the mass of the Milky Way galaxy to clumps no more massive than the heft of a commercial airplane. (In this context, "cold" refers to the particles' speed.)
The Hubble observation yields new insights into the nature of dark matter and how it behaves. "We made a very compelling observational test for the cold dark matter model and it passes with flying colors," said Tommaso Treu of the University of California, Los Angeles (UCLA), a member of the observing team.
Dark matter is an invisible form of matter that makes up the bulk of the universe's mass and creates the scaffolding upon which galaxies are built. Although astronomers cannot see dark matter, they can detect its presence indirectly by measuring how its gravity affects stars and galaxies. Detecting the smallest dark matter formations by looking for embedded stars can be difficult or impossible, because they contain very few stars.
While dark matter concentrations have been detected around large- and medium-sized galaxies, much smaller clumps of dark matter have not been found until now. In the absence of observational evidence for such small-scale clumps, some researchers have developed alternative theories, including "warm dark matter." This idea suggests that dark matter particles are fast moving, zipping along too quickly to merge and form smaller concentrations. The new observations do not support this scenario, finding that dark matter is "colder" than it would have to be in the warm dark matter alternative theory.
"Dark matter is colder than we knew at smaller scales," said Anna Nierenberg of NASA's Jet Propulsion Laboratory in Pasadena, California, leader of the Hubble survey. "Astronomers have carried out other observational tests of dark matter theories before, but ours provides the strongest evidence yet for the presence of small clumps of cold dark matter. By combining the latest theoretical predictions, statistical tools and new Hubble observations, we now have a much more robust result than was previously possible."
Hunting for dark matter concentrations devoid of stars has proved challenging. The Hubble research team, however, used a technique in which they did not need to look for the gravitational influence of stars as tracers of dark matter. The team targeted eight powerful and distant cosmic "streetlights," called quasars (regions around active black holes that emit enormous amounts of light). The astronomers measured how the light emitted by oxygen and neon gas orbiting each of the quasars' black holes is warped by the gravity of a massive foreground galaxy, which is acting as a magnifying lens.
bright quasar "dots" against black backgrounds of space
Each of these Hubble Space Telescope snapshots reveals four distorted images of a background quasar and its host galaxy surrounding the central core of a foreground massive galaxy. The gravity of the massive foreground galaxy is acting like a magnifying glass by warping the quasar’s light in an effect called gravitational lensing. Quasars are extremely distant cosmic streetlights produced by active black holes. Such quadruple images of quasars are rare because of the nearly exact alignment needed between the foreground galaxy and background quasar. Astronomers used the gravitational lensing effect to detect the smallest clumps of dark matter ever found. The clumps are located along the telescope's line of sight to the quasars, as well as in and around the foreground lensing galaxies. The presence of the dark matter concentrations alters the apparent brightness and position of each distorted quasar image. Astronomers compared these measurements with predictions of how the quasar images would look without the influence of the dark matter clumps. The researchers used these measurements to calculate the masses of the tiny dark matter concentrations. Hubble's Wide Field Camera 3 captured the near-infrared light from each quasar and dispersed it into its component colors for study with spectroscopy. The images were taken between 2015 and 2018.
Credits: NASA, ESA, A. Nierenberg (JPL) and T. Treu (UCLA)
Using this method, the team uncovered dark matter clumps along the telescope's line of sight to the quasars, as well as in and around the intervening lensing galaxies. The dark matter concentrations detected by Hubble are 1/10,000th to 1/100,000th times the mass of the Milky Way's dark matter halo. Many of these tiny groupings most likely do not contain even small galaxies, and therefore would have been impossible to detect by the traditional method of looking for embedded stars.
The eight quasars and galaxies were aligned so precisely that the warping effect, called gravitational lensing, produced four distorted images of each quasar. The effect is like looking at a funhouse mirror. Such quadruple images of quasars are rare because of the nearly exact alignment needed between the foreground galaxy and background quasar. However, the researchers needed the multiple images to conduct a more detailed analysis.
graphic showing a quasar's light, warped to appear like four quasars to Hubble because of a massive galaxy in between
This graphic illustrates how a faraway quasar's light is altered by a massive foreground galaxy and by tiny dark matter clumps along the light path. The galaxy's powerful gravity warps and magnifies the quasar's light, producing four distorted images of the quasar.The dark matter clumps reside along the Hubble Space Telescope's line of sight to the quasar, as well as within and around the foreground galaxy. The presence of the dark matter clumps alters the apparent brightness and position of each distorted quasar image by warping and slightly bending the light as it travels from the distant quasar to Earth, as represented by the wiggly lines in the graphic. Astronomers compared these measurements with predictions of how the quasar images would look without the influence of the dark matter clumps. The researchers used these measurements to calculate the masses of the tiny dark matter concentrations. Quadruple images of a quasar are rare because the background quasar and foreground galaxy require an almost perfect alignment.
Credits: NASA, ESA and D. Player (STScI)
The presence of the dark matter clumps alters the apparent brightness and position of each distorted quasar image. Astronomers compared these measurements with predictions of how the quasar images would look without the influence of the dark matter. The researchers used the measurements to calculate the masses of the tiny dark matter concentrations. To analyze the data, the researchers also developed elaborate computing programs and intensive reconstruction techniques.
"Imagine that each one of these eight galaxies is a giant magnifying glass," explained team member Daniel Gilman of UCLA. "Small dark matter clumps act as small cracks on the magnifying glass, altering the brightness and position of the four quasar images compared to what you would expect to see if the glass were smooth."
The researchers used Hubble’s Wide Field Camera 3 to capture the near-infrared light from each quasar and disperse it into its component colors for study with spectroscopy. Unique emissions from the background quasars are best seen in infrared light. "Hubble's observations from space allow us to make these measurements in galaxy systems that would not be accessible with the lower resolution of ground-based telescopes—and Earth's atmosphere is opaque to the infrared light we needed to observe," explained team member Simon Birrer of UCLA.
Treu added: "It's incredible that after nearly 30 years of operation, Hubble is enabling cutting-edge views into fundamental physics and the nature of the universe that we didn't even dream of when the telescope was launched."
The gravitational lenses were discovered by sifting through ground-based surveys such as the Sloan Digital Sky Survey and Dark Energy Survey, which provide the most detailed three-dimensional maps of the universe ever made. The quasars are located roughly 10 billion light-years from Earth; the foreground galaxies, about 2 billion light-years.
The number of small structures detected in the study offers more clues about dark matter's nature. "The particle properties of dark matter affect how many clumps form," Nierenberg explained. "That means you can learn about the particle physics of dark matter by counting the number of small clumps."
However, the type of particle that makes up dark matter is still a mystery. "At present, there's no direct evidence in the lab that dark matter particles exist," Birrer said. "Particle physicists would not even talk about dark matter if the cosmologists didn’t say it's there, based on observations of its effects. When we cosmologists talk about dark matter, we're asking 'how does it govern the appearance of the universe, and on what scales?'"
Astronomers will be able to conduct follow-up studies of dark matter using future NASA space telescopes such as the James Webb Space Telescope and the Wide Field Infrared Survey Telescope (WFIRST), both infrared observatories. Webb will be capable of efficiently obtaining these measurements for all known quadruply lensed quasars. WFIRST's sharpness and large field of view will help astronomers make observations of the entire region of space affected by the immense gravitational field of massive galaxies and galaxy clusters. This will help researchers uncover many more of these rare systems.
The team will present its results at the 235th meeting of the American Astronomical Society in Honolulu, Hawaii.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Claire Andreoli
NASA's Goddard Space Flight Center, Greenbelt, Md.
301-286-1940
claire.andreoli@nasa.gov
Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu
Anna Nierenberg
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-5095
anna.m.nierenberg@jpl.nasa.gov
Tommaso Treu / Daniel Gilman
University of California, Los Angeles
310-206-5617 (office) / 757-814-5869 (cell)
tt@astro.ucla.edu / gilmanda@ucla.edu
Last Updated: Jan. 14, 2020
Editor: Rob Garner

Hubble Makes Surprising Find in Early Universe | NASA

Hubble Makes Surprising Find in Early Universe | NASA



Hubble Makes Surprising 

Find in Early Universe

New results from the NASA/ESA Hubble Space Telescope suggest the formation of the first stars and galaxies in the early universe took place sooner than previously thought. A European team of astronomers have found no evidence of the first generation of stars, known as Population III stars, as far back as when the universe was just 500 million years old.
The exploration of the very first galaxies remains a significant challenge in modern astronomy. We do not know when or how the first stars and galaxies in the universe formed. These questions can be addressed with the Hubble Space Telescope through deep imaging observations. Hubble allows astronomers to view the universe back to within 500 million years of the big bang.
red-hued flecks of light against a black backdrop
New results from the Hubble Space Telescope suggest the formation of the first stars and galaxies in the early universe took place sooner than previously thought. A European team of astronomers have found no evidence of the first generation of stars, known as Population III stars, when the universe was less than 1 billion years old. This artist's impression presents the early universe.
Credits: ESA/Hubble, M. Kornmesser and NASA
A team of European researchers, led by Rachana Bhatawdekar of ESA (the European Space Agency), set out to study the first generation of stars in the early universe. Known as Population III stars, these stars were forged from the primordial material that emerged from the big bang. Population III stars must have been made solely out of hydrogen, helium and lithium, the only elements that existed before processes in the cores of these stars could create heavier elements, such as oxygen, nitrogen, carbon and iron.
Bhatawdekar and her team probed the early universe from about 500 million to 1 billion years after the big bang by studying the cluster MACS J0416 and its parallel field with the Hubble Space Telescope (with supporting data from NASA's Spitzer Space Telescope and the ground-based Very Large Telescope of the European Southern Observatory). "We found no evidence of these first-generation Population III stars in this cosmic time interval," said Bhatawdekar of the new results.
Hubble image of galaxy cluster MACS J0416 showing a starry sky scene with central blue smear
This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster MACS J0416. This is one of six galaxy clusters being studied by the Hubble Frontier Fields program, which produced the deepest images of gravitational lensing ever made. Scientists used intracluster light (visible in blue) to study the distribution of dark matter within the cluster.
Credits: NASA, ESA and M. Montes (University of New South Wales)
The result was achieved using the Hubble Space Telescope's Wide Field Camera 3 and Advanced Camera for Surveys, as part of the Hubble Frontier Fields program. This program (which observed six distant galaxy clusters from 2012 to 2017) produced the deepest observations ever made of galaxy clusters and the galaxies located behind them which were magnified by the gravitational lensing effect, thereby revealing galaxies 10 to 100 times fainter than any previously observed. The masses of foreground galaxy clusters are large enough to bend and magnify the light from the more distant objects behind them. This allows Hubble to use these cosmic magnifying glasses to study objects that are beyond its nominal operational capabilities.
Bhatawdekar and her team developed a new technique that removes the light from the bright foreground galaxies that constitute these gravitational lenses. This allowed them to discover galaxies with lower masses than ever previously observed with Hubble, at a distance corresponding to when the universe was less than a billion years old. At this point in cosmic time, the lack of evidence for exotic stellar populations and the identification of many low-mass galaxies supports the suggestion that these galaxies are the most likely candidates for the reionization of the universe. This period of reionization in the early universe is when the neutral intergalactic medium was ionized by the first stars and galaxies.
"These results have profound astrophysical consequences as they show that galaxies must have formed much earlier than we thought," said Bhatawdekar. "This also strongly supports the idea that low-mass/faint galaxies in the early universe are responsible for reionization."
These results also suggest that the earliest formation of stars and galaxies occurred much earlier than can be probed with the Hubble Space Telescope. This leaves an exciting area of further research for the upcoming NASA/ESA/CSA James Webb Space Telescope — to study the universe's earliest galaxies.
These results are based on a previous 2019 paper by Bhatawdekar et al., and a paper that will appear in an upcoming issue of the Monthly Notices of the Royal Astronomical Society (MNRAS). These results are also being presented at a press conference during the 236th meeting of American Astronomical Society.
The European team of astronomers in this study consists of R. Bhatawdekar and C.J. Conselice.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Claire Andreoli
NASA's Goddard Space Flight Center, Greenbelt, Md.
301-286-1940
claire.andreoli@nasa.gov
Bethany Downer
ESA/Hubble, Garching, Germany
bethany.downer@partner.eso.org
Rachana Bhatawdekar
ESA / ESTEC, Noordwijk, The Netherlands
rachana.bhatawdekar@esa.int
Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4514
villard@stsci.edu
Last Updated: June 4, 2020
Editor: Rob Garner

Shining a Light on Dark Matter | NASA

Shining a Light on Dark Matter | NASA



Shining a Light on Dark Matter

Dark matter
Dark matter, although invisible, makes up most of the universe’s mass and creates its underlying structure. Dark matter’s gravity drives normal matter (gas and dust) to collect and build up into stars and galaxies. Although astronomers cannot see dark matter, they can detect its influence by observing how the gravity of massive galaxy clusters, which contain dark matter, bends and distorts the light of more-distant galaxies located behind the cluster.
As seen in this image, large galaxy clusters contain both dark and normal matter. The immense gravity of all this material warps the space around the cluster, causing the light from objects located behind the cluster to be distorted and magnified. This phenomenon is called gravitational lensing. This sketch shows paths of light from a distant galaxy that is being gravitationally lensed by a foreground cluster.
In 1609, visionary scientist Galileo Galilei turned the newly invented optical device of his day — the telescope — to view the heavens. Almost four centuries later, the launch of NASA’s Hubble Space Telescope aboard the space shuttle Discovery in 1990 started another revolution in astronomy. Developed as a partnership between the United States space program and the European Space Agency, Hubble orbits 340 miles above Earth’s surface. 
Along with pictures of the telescope and the astronauts who launched and serviced it during six space shuttle missions, certain memorable science images have become cultural icons. They appear regularly on book covers, music albums, clothing, TV shows, movies and even ecclesiastical stained-glass windows.
Additional images and information can be found at https://hubblesite.org.
Image Credit: NASA/ESA
Last Updated: April 30, 2020
Editor: Yvette Smith

Universe’s Expansion May Not Be The Same In All Directions | NASA

Universe’s Expansion May Not Be The Same In All Directions | NASA



Universe’s Expansion 

May Not Be The Same 

In All Directions

One of the fundamental ideas of cosmology is that everything looks the same in all directions if you look over large enough distances. A new study using data from NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton is challenging that basic notion.
Astronomers using X-ray data from these orbiting observatories studied hundreds of galaxy clusters, the largest structures in the universe held together by gravity, and how their apparent properties differ across the sky.
This graphic contains a map of the full sky and shows four of the hundreds of galaxy clusters that were analyzed.
This graphic contains a map of the full sky and shows four of the hundreds of galaxy clusters that were analyzed to test whether the Universe is the same in all directions over large scales.
Credits: NASA/CXC/Univ. of Bonn/K. Migkas et al.; Illustration: NASA/CXC/M. Weiss
“One of the pillars of cosmology – the study of the history and fate of the entire universe – is that the universe is ‘isotropic,’ meaning the same in all directions,” said Konstantinos Migkas of the University of Bonn in Germany, who led the new study. “Our work shows there may be cracks in that pillar.”
Astronomers generally agree that after the Big Bang, the cosmos has continuously expanded. A commonly analogy is that this expansion is like a baking loaf of raisin bread. As the bread bakes, the raisins (which represent cosmic objects like galaxies and galaxy clusters) all move away from one another as the entire loaf (representing space) expands. With an even mix the expansion should be uniform in all directions, as it should be with an isotropic universe. But these new results may not fit that picture.
“Based on our cluster observations we may have found differences in how fast the universe is expanding depending on which way we looked,” said co-author Gerrit Schellenberger of the Center for Astrophysics | Harvard & Smithsonian (CfA) in Cambridge, Massachusetts. “This would contradict one of the most basic underlying assumptions we use in cosmology today.”
Scientists have previously conducted many tests of whether the universe is the same in all directions. These included using optical observations of exploded stars and infrared studies of galaxies. Some of these previous efforts have produced possible evidence that the universe is not isotropic, and some have not.
This latest test uses a powerful, novel and independent technique. It capitalizes on the relationship between the temperature of the hot gas pervading a galaxy cluster and the amount of X-rays it produces, known as the cluster's X-ray luminosity. The higher the temperature of the gas in a cluster, the higher the X-ray luminosity is. Once the temperature of the cluster gas is measured, the X-ray luminosity can be estimated. This method is independent of cosmological quantities, including the expansion speed of the universe.
Once they estimated the X-ray luminosities of their clusters using this technique, scientists then calculated luminosities using a different method that does depend on cosmological quantities, including the universe’s expansion speed. The results gave the researchers apparent expansion speeds across the whole sky – revealing that the universe appears to be moving away from us faster in some directions than others.
The team also compared this work with studies from other groups that have found indications of a lack of isotropy using different techniques. They found good agreement on the direction of the lowest expansion rate.
The authors of this new study came up with two possible explanations for their results that involve cosmology. One of these explanations is that large groups of galaxy clusters might be moving together, but not because of cosmic expansion. For example, it is possible some nearby clusters are being pulled in the same direction by the gravity of groups of other galaxy clusters. If the motion is rapid enough it could lead to errors in estimating the luminosities of the clusters.
These sorts of correlated motions would give the appearance of different expansion rates in different directions. Astronomers have seen similar effects with relatively nearby galaxies, at distances typically less than 850 million light years, where mutual gravitational attraction is known to control the motion of objects. However, scientists expected the expansion of the universe to dominate the motion of clusters across larger distances, up to the 5 billion light years probed in this new study.
A second possible explanation is that the universe is not actually the same in all directions. One intriguing reason could be that dark energy – the mysterious force that seems to be driving acceleration of the expansion of the universe – is itself not uniform. In other words, the X-rays may reveal that dark energy is stronger in some parts of the universe than others, causing different expansion rates.
“This would be like if the yeast in the bread isn’t evenly mixed, causing it to expand faster in some places than in others,” said co-author Thomas Reiprich, also of the University of Bonn. "It would be remarkable if dark energy were found to have different strengths in different parts of the universe. However, much more evidence would be needed to rule out other explanations and make a convincing case."
Either of these two cosmological explanations would have significant consequences. Many studies in cosmology, including X-ray studies of galaxy clusters, assume that the universe is isotropic and that correlated motions are negligible compared to the cosmic expansion at the distances probed here.
The team used a sample of 313 galaxy clusters for their analysis, containing 237 clusters observed by Chandra with a total of 191 days of exposure, and 76 observed by XMM-Newton, with a total of 35 days of exposure. They also combined their sample of galaxy clusters with two other large X-ray samples, using data from XMM-Newton and the Japan-US Advanced Satellite for Cosmology and Astrophysics (ASCA), giving a total of 842 different galaxy clusters. They found a similar result using the same technique.
A paper describing these results will appear in the April 2020 issue of the journal Astronomy and Astrophysics and is available online. In addition to Migkas, Schellenberger and Reiprich, the authors of this paper are Florian Pacaud and Miriam Elizabeth Ramos-Ceja (University of Bonn), and Lorenzo Lovisari (CfA).
NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science and flight operations from Cambridge and Burlington, Massachusetts.
For more Chandra images, multimedia and related materials, visit:
Molly Porter
Marshall Space Flight Center, Huntsville, Ala.
256-544-0034
molly.a.porter@nasa.gov
Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu
Last Updated: April 9, 2020
Editor: Lee Mohon

Slime Mold Simulations Map Dark Matter Holding Universe Together | NASA

Slime Mold Simulations Map Dark Matter Holding Universe Together | NASA



Slime Mold Simulations 

Used to Map Dark Matter 

Holding Universe Together

The behavior of one of nature's humblest creatures is helping astronomers probe the largest structures in the universe.
The single-cell organism, known as slime mold (Physarum polycephalum), builds complex filamentary networks in search of food, finding near-optimal pathways to connect different locations. In shaping the universe, gravity builds a vast cobweb structure of filaments tying galaxies and clusters of galaxies together along faint bridges hundreds of millions of light-years long. There is an uncanny resemblance between the two networks: one crafted by biological evolution, and the other by the primordial force of gravity.
The cosmic web is the large-scale backbone of the cosmos, consisting primarily of the mysterious substance known as dark matter and laced with gas, upon which galaxies are built. Dark matter cannot be seen, but it makes up the bulk of the universe's material. The existence of a web-like structure to the universe was first hinted at in the 1985 Redshift Survey conducted at the Harvard-Smithsonian Center for Astrophysics. Since those studies, the grand scale of this filamentary structure has grown in subsequent sky surveys. The filaments form the boundaries between large voids in the universe.
But astronomers have had a difficult time finding these elusive strands, because the gas is so dim it is hard to detect. Now a team of researchers has turned to slime mold to help them build a map of the filaments in the local universe (within 500 million light-years from Earth) and find the gas within them.
They designed a computer algorithm, inspired by slime-mold behavior, and tested it against a computer simulation of the growth of dark matter filaments in the universe. A computer algorithm is similar to a recipe that tells a computer precisely what steps to take to solve a problem.
The researchers then applied the slime mold algorithm to data containing the locations of 37,000 galaxies mapped by the Sloan Digital Sky Survey at distances corresponding to 300 million light-years. The algorithm produced a three-dimensional map of the underlying cosmic web structure.
They then analyzed the ultraviolet light from 350 quasars (at much farther distances of billions of light-years) cataloged in the Hubble Spectroscopic Legacy Archive, which holds the data from NASA's Hubble Space Telescope's spectrographs. These distant cosmic flashlights are the brilliant black-hole-powered cores of active galaxies, whose light shines across space and through the foreground cosmic web. Imprinted on that light was the telltale absorption signature of otherwise undetected hydrogen gas that the team analyzed at specific points along the filaments. These target locations are far from the galaxies, which allowed the research team to link the gas to the universe's large-scale structure.
purple illustration of slime mold growth
Astronomers have gotten creative in trying to trace the elusive cosmic web, the large-scale backbone of the cosmos. Researchers turned to slime mold, a single-cell organism found on Earth, to help them build a map of the filaments in the local universe (within 500 million light-years from Earth) and find the gas within them. The researchers designed a computer algorithm inspired by the organism's behavior and applied it to data containing the positions of 37,000 galaxies ("food" for the slime mold) mapped by the Sloan Digital Sky Survey. The algorithm produced a three-dimensional map of the underlying cosmic web's intricate filamentary network, the purple structure in the image. The three sets of inset boxes show some of those individual galaxies that were "fed" to the slime mold and the filamentary structure connecting them. The galaxies are represented by the yellow dots in three of the inset images. Next to each galaxy snapshot is an image of the galaxies with the cosmic web's connecting strands (purple) superimposed on them.
Credits: NASA, ESA, and J. Burchett and O. Elek (UC Santa Cruz)
"It's really fascinating that one of the simplest forms of life actually enables insight into the very largest-scale structures in the universe," said lead researcher Joseph Burchett of the University of California (UC), Santa Cruz. "By using the slime-mold simulation to find the location of the cosmic web filaments, including those far from galaxies, we could then use the Hubble Space Telescope's archival data to detect and determine the density of the cool gas on the very outskirts of those invisible filaments. Scientists have detected signatures of this gas for several decades, and we have proven the theoretical expectation that this gas comprises the cosmic web."
The survey further validates research that denser regions of intergalactic gas is organized into filaments that the team found stretches over 10 million light-years from galaxies. (That distance is more than 100 times the diameter of our Milky Way galaxy.)
The researchers turned to slime mold simulations when they were searching for a way to visualize the theorized connection between the cosmic web structure and the cool gas detected in previous Hubble spectroscopic studies.
Then team member Oskar Elek, a computational media scientist at UC Santa Cruz, discovered online the work of Sage Jenson, a Berlin-based media artist. Among Jenson's works were mesmerizing artistic visualizations showing the growth of a slime mold's tentacle-like network of food-seeking structures. Jenson's art was based on outside scientific research, which detailed an algorithm for simulating the growth of slime mold.
The research team noted a striking similarity between how the slime mold builds complex filaments to capture new food, and how gravity, in shaping the universe, constructs the cosmic web strands between galaxies and galaxy clusters.
Based on the simulation, Elek developed a three-dimensional computer model of the buildup of slime mold to estimate the location of the cosmic web's filamentary structure.
Although using a slime-mold-inspired simulation to pinpoint the universe's largest structures may sound bizarre at first, scientists have used computer models of these humble microorganisms, as well as grown them in petri dishes in a lab, to solve such complex problems as finding the most efficient traffic routes in large cities, solving mazes and pinpointing crowd evacuation routes. "These are hard problems to solve for a human, let alone a computer algorithm," Elek said.
"You can almost see, especially in the map of galaxies in the local universe from the Sloan data, where the filaments should be," Burchett explained. "The slime-mold model fits that intuition impressively. The structure that you know should be there is all of a sudden found by the computer algorithm. There was no other known method that was well suited to this problem for our research."
The researchers say that it is very difficult to design a reliable algorithm for finding the filaments in such a large survey of galaxies. "So it's quite amazing to see that the virtual slime mold gives you a very close approximation in just minutes," Elek explained. "You can literally watch it grow." Just for comparison, growing the organism in a petri dish takes days. Slime mold actually has a very special kind of intelligence for solving this one spatial task. After all, it's critical to its survival.
The team's paper will appear in The Astrophysical Journal Letters.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Claire Andreoli
NASA's Goddard Space Flight Center, Greenbelt, Md.
301-286-1940
claire.andreoli@nasa.gov
Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu
Joseph Burchett / Oskar Elek
UC Santa Cruz, Santa Cruz, California
burchett@ucolick.org / oelek@ucsc.edu
Last Updated: March 10, 2020
Editor: Rob Garner

Hunting Dark Matter with Supernova Explosions – ECAP

Hunting Dark Matter with Supernova Explosions – ECAP

ECAP



Hunting Dark Matter with Supernova Explosions



An artist impression of the Fermi LAT observing a supernova producing axions. Image credit: Maedeh Mohammadpour Mir


The nature of dark matter, the substance that accounts for more than 85% of all matter in the Universe, remains a mystery. Many theories predict that dark matter is made up from yet undiscovered fundamental particles and a plethora of experiments on Earth and in Space are looking for traces of them. A new study by Manuel Meyer of the Erlangen Center of Astroparticle Physics at FAU and Tanja Petrushevska of the Center for Astrophysics and Cosmology at the University of Nova Gorica suggests how researchers can use explosions of stars outside the Milky Way to search for a particular class of dark matter particles.

NASA Plans for More SLS Rocket Boosters to Launch Artemis Missions | NASA

NASA Plans for More SLS Rocket Boosters to Launch Artemis Missions | NASA



NASA Plans for More 

SLS Rocket Boosters 

to Launch Artemis Moon Missions

The Space Launch System (SLS) rocket booster segments
Exploration Ground System teams are processing the Artemis I booster segments and preparing to stack them with forward and aft assemblies at NASA’s Kennedy Space Center in Florida. The Space Launch System (SLS) rocket booster segments arrived on June 15 by trains traveling from Utah near Northrop Grumman’s facility where they were manufactured. Northrop Grumman has already produced the booster segments for the Artemis II mission and is in the process of manufacturing the rocket motors for the Artemis III. The SLS twin solid rocket boosters provide more than 75 percent of the power to launch the rocket on the Artemis missions to the Moon.
Credits: NASA
NASA has taken the next steps toward building Space Launch System (SLS) solid rocket boosters to support as many as six additional flights, for a total of up to nine Artemis missions. The agency is continuing to work with Northrop Grumman of Brigham City, Utah, the current lead contractor for the solid rocket boosters that will launch the first three Artemis missions, including the mission that will land the first woman and next man on the Moon in 2024.
Under this letter contract, with a potential value of $49.5 million, NASA will provide initial funding and authorization to Northrop Grumman to order long-lead items to support building the twin boosters for the next six SLS flights. Northrop Grumman will be able to make purchases as the details of the full contract are finalized within the next year. The full Boosters Production and Operations Contract is expected to support booster production and operations for SLS flights 4-9. The period of performance for the letter contract is 150 days; the definitized contract will extend through Dec. 31, 2030.
“This initial step ensures that NASA can build the boosters needed for future Space Launch System rockets that will be needed for the Artemis missions to explore the Moon,” said John Honeycutt, SLS Program Manager at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “The letter contract allows us to buy long-lead materials in time for manufacturing boosters for the fourth flight.”
The twin solid rocket boosters, which are mounted on the side of the SLS core stage, will produce more than 75% percent of the thrust for each SLS launch. The boosters were based on the design of the space shuttle solid rocket boosters but include a fifth segment to produce the extra power needed to send the larger SLS rocket to space.
“We’re ready to process and stack the boosters for the Artemis I mission, and we are making great progress producing boosters for the Artemis II and III missions,” said Bruce Tiller, manager of the SLS Boosters office at Marshall. “NASA is committed to establishing a sustainable presence at the Moon, and this action enables NASA to have boosters ready when needed for future missions.”
Northrop Grumman has delivered the 10 solid rocket booster segments  to NASA’s Kennedy Space Center in Florida. There they will be stacked with other booster components outfitted at Kennedy and readied for launch. Casting is complete for the solid rocket motor segments for Artemis II and is underway for the Artemis III crew lunar landing mission.
Recently, NASA conducted SLS procurement activities to acquire additional RS-25 engines and core stages for future SLS flights. The Interim Cryogenic Propulsion Stage for the second Artemis mission, as well as the launch vehicle stage adapter and Orion stage adapter are in the initial phase of manufacturing in Alabama.
The SLS rocket, Orion spacecraft, Gateway and Human Landing System are part of NASA’s backbone for deep space exploration. The Artemis program is the next step in human space exploration. It’s part of America’s broader Moon to Mars exploration approach, in which astronauts will explore the Moon and experience gained there to enable humanity’s next giant leap, sending humans to Mars.
For more information on SLS, visit:
-end-
Kathryn Hambleton
Headquarters, Washington
202-358-1409
kathryn.hambleton@nasa.gov
Tracy McMahan
Marshall Space Flight Center, Huntsville, Ala.
256-544-0034
tracy.mcmahan@nasa.gov
Last Updated: June 29, 2020
Editor: Sean Potter