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  • richardmitnick 10:10 am on May 8, 2017 Permalink | Reply
    Tags: , , Frontier Fields, Hubble Views The Final Frontier For Dark Matter,   

    From Ethan Siegel: “Hubble Views The Final Frontier For Dark Matter” 

    Ethan Siegel
    May 8, 2017

    The streaks and arcs present in Abell 370, a distant galaxy cluster some 5-6 billion light years away, are some of the strongest evidence for gravitational lensing and dark matter that we have. NASA, ESA/Hubble, HST Frontier Fields

    When you look out into the distant Universe, in most locations, you’ll find a field of faint, distant galaxies: beautiful, but nothing special.

    The ‘parallel field’ of Abell 370 showcases a deep view of a region of space with no particularly massive or significant structure inside. This is what most of the Universe looks like, when imaged deeply enough. NASA, ESA/Hubble, HST Frontier Fields

    Six billion light years away, Abell 370 is one of the most massive, dense ones discovered so far, but one galaxy, noticed early on, provided a hint of something more.

    The distorted galaxy shown here is actually two images of a single galaxy located twice as far away as the rest of the galaxy; it is the effects of gravitational lensing that cause the odd appearance and multiple images. NASA, ESA/Hubble, HST Frontier Fields

    The “stretched-out” galaxy you see here isn’t a distorted cluster member, but is instead two images of a single galaxy, twice as far away as the cluster itself.

    An illustration of gravitational lensing showcases how background galaxies — or any light path — is distorted by the presence of an intervening mass, such as a foreground galaxy cluster. NASA/ESA

    This phenomenon of gravitational lensing stretches galaxies into streaks and arcs, magnifying them, and creating multiple images.

    The streaks of galaxies shown here are not representative of the actual shapes of the galaxies themselves, but rather the galaxies subject to the effects of the gravitational lens they pass through. Undistorted galaxies, like the one at the top left, are most likely in the foreground of the lens. NASA, ESA/Hubble, HST Frontier Fields

    It also enables us to reconstruct the mass distribution of the cluster, revealing that it’s mostly due to dark matter.

    The mass distribution of cluster Abell 370. reconstructed through gravitational lensing, shows two large, diffuse halos of mass, consistent with dark matter with two merging clusters to create what we see here. NASA, ESA, D. Harvey (École Polytechnique Fédérale de Lausanne, Switzerland), R. Massey (Durham University, UK), the Hubble SM4 ERO Team and ST-ECF

    There are two separate clumps present, showing that this is likely two clusters merging together.

    Despite the presence of large, elliptical galaxies, the location where the mass density is greatest, indicated by the dotted circle, corresponds to no known massive galaxy or other structure based in normal matter. The only explanation for this is the presence of an invisible source of mass: dark matter. NASA, ESA/Hubble, HST Frontier Fields / E. Siegel (annotation)

    Most importantly, dark matter must be present — and present outside of the individual galaxies themselves — to explain these gravitational effects.

    A 2009 image, based on only a fraction of the Hubble data available today, revealed some of the incredible structure in Abell 370. The current data, benefitting from 8 extra years, showcases even more information about the distant, massive Universe. NASA/ESA Hubble

    Additional observations from 2009-2017 reveal unprecedented details about the massive, distant Universe.

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

  • richardmitnick 12:20 pm on May 4, 2017 Permalink | Reply
    Tags: , , , , Frontier Fields,   

    From Hubble: “The final frontier of the Frontier Fields” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    4 May 2017
    Mathias Jäger
    ESA/Hubble, Public Information Officer
    Garching bei München, Germany
    Tel: +49 176 6239750

    The NASA/ESA Hubble Telescope has peered across six billion light years of space to resolve extremely faint features of the galaxy cluster Abell 370 that have not been seen before. Imaged here in stunning detail, Abell 370 is part of the Frontier Fields programme which uses massive galaxy clusters to study the mysteries of dark matter and the very early Universe.

    Six billion light-years away in the constellation Cetus (the Sea Monster), Abell 370 is made up of hundreds of galaxies [1]. Already in the mid-1980s higher-resolution images of the cluster showed that the giant luminous arc in the lower left of the image was not a curious structure within the cluster, but rather an astrophysical phenomenon: the gravitationally lensed image of a galaxy twice as far away as the cluster itself. Hubble helped show that this arc is composed of two distorted images of an ordinary spiral galaxy that just happens to lie behind the cluster.

    Abell 370’s enormous gravitational influence warps the shape of spacetime around it, causing the light of background galaxies to spread out along multiple paths and appear both distorted and magnified. The effect can be seen as a series of streaks and arcs curving around the centre of the image. Massive galaxy clusters can therefore act like natural telescopes, giving astronomers a close-up view of the very distant galaxies behind the cluster — a glimpse of the Universe in its infancy, only a few hundred million years after the Big Bang.

    This image of Abell 370 was captured as part of the Frontier Fields programme, which used a whopping 630 hours of Hubble observing time, over 560 orbits of the Earth. Six clusters of galaxies were imaged in exquisite detail, including Abell 370 which was the very last one to be finished. An earlier image of this object — using less observation time and therefore not recording such faint detail — was published in 2009.

    During the cluster observations, Hubble also looked at six “parallel fields”, regions near the galaxy clusters which were imaged with the same exposure times as the clusters themselves. Each cluster and parallel field were imaged in infrared light by the Wide Field Camera 3 (WFC3), and in visible light by the Advanced Camera for Surveys (ACS).

    NASA/ESA Hubble WFC3

    NASA/ESA Hubble ACS

    The Frontier Fields programme produced the deepest observations ever made of galaxy clusters and the magnified galaxies behind them. These observations are helping astronomers understand how stars and galaxies emerged out of the dark ages of the Universe, when space was dark, opaque, and filled with hydrogen.

    Studying massive galaxy clusters like Abell 370 also helps with measuring the distribution of normal matter and dark matter within such clusters [heic1506]. By studying its lensing properties, astronomers have determined that Abell 370 contains two large, separate clumps of dark matter, contributing to the evidence that this massive galaxy cluster is actually the result of two smaller clusters merging together.

    Now that the observations for the Frontier Fields programme are complete, astronomers can use the full dataset to explore the clusters, their gravitational lensing effects and the magnified galaxies from the early Universe in full detail.


    [1] Galaxy clusters are the most massive structures in the Universe that are held together by gravity, generally thought to have formed when smaller groups of galaxies smashed into each other in ever-bigger cosmic collisions. Such clusters can contain up to 1000 galaxies, along with hot intergalactic gas that often shines brightly at X-ray wavelengths, all bound together primarily by the gravity of dark matter.


    Images of Hubble
    Hubblesite release
    Frontier Fields

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 9:15 am on February 9, 2017 Permalink | Reply
    Tags: , , , , , Faintest galaxies yet seen in the early universe, Frontier Fields, , ,   

    From U Texas at Austin: “Astronomers Find Faintest Early Galaxies Yet, Probe How the Early Universe Lit Up” 

    U Texas Austin bloc

    University of Texas at Austin

    08 February 2017
    No writer credit

    Astronomers at The University of Texas at Austin have developed a new technique to discover the faintest galaxies yet seen in the early universe —10 times fainter than any previously seen.

    A Hubble Space Telescope view of the galaxy cluster Abell 2744.

    These galaxies will help astronomers probe a little-understood, but important period in cosmic history. Their new technique helps probe the time a billion years after the Big Bang, when the early, dark universe was flooded with light from the first galaxies.

    Rachael Livermore and Steven Finkelstein of the UT Austin Astronomy Department, along with Jennifer Lotz of the Space Telescope Science Institute, went looking for these faint galaxies in images from Hubble Space Telescope’s Frontier Fields survey.

    A Hubble Space Telescope view of the galaxy cluster MACS 0416 is annotated in cyan and magenta to show how it acts as a ‘gravitational lens,’ magnifying more distant background galaxies.

    “These galaxies are actually extremely common,” Livermore said. “It’s very satisfying being able to find them.”

    These faint, early galaxies gave rise to the Epoch of Reionization, when the energetic radiation they gave off bombarded the gas between all galaxies in the universe. This caused the atoms in this diffuse gas to lose their electrons (that is, become ionized).

    Finkelstein explained why finding these faint galaxies is so important. “We knew ahead of time that for our idea of galaxy-powered reionization to work, there had to be galaxies a hundred times fainter than we could see with Hubble,” he said, “and they had to be really, really common.” This was why the Hubble Frontier Fields program was created, he said.

    Lotz leads the Hubble Frontier Fields project, one of the telescope’s largest to date. In it, Hubble photographed several large galaxy clusters. These were selected to take advantage of their enormous mass which causes a useful optical effect, predicted by Albert Einstein. A galaxy cluster’s immense gravity bends space, which magnifies light from more-distant galaxies behind it as that light travels toward the telescope. Thus the galaxy cluster acts as a magnifying glass, or a “gravitational lens,” allowing astronomers to see those more-distant galaxies — ones they would not normally be able to detect, even with Hubble.

    Even then, though, the lensed galaxies were still just at the cusp of what Hubble could detect.

    “The main motivation for the Frontier Fields project was to search for these extremely faint galaxies during this critical period in the universe’s history,” Lotz said. “However, the primary difficulty with using the Frontier Field clusters as an extra magnifying glass is how to correct for the contamination from the light of the cluster galaxies.”

    Livermore elaborates: “The problem is, you’re trying to find these really faint things, but you’re looking behind these really bright things. The brightest galaxies in the universe are in clusters, and those cluster galaxies are blocking the background galaxies we’re trying to observe. So what I did was come up with a method of removing the cluster galaxies” from the images.

    Her method uses modeling to identify and separate light from the foreground galaxies (the cluster galaxies) from the light coming from the background galaxies (the more-distant, lensed galaxies).

    According to Lotz, “This work is unique in its approach to removing this light. This has allowed us to detect more and fainter galaxies than seen in previous studies, and to achieve the primary goal for the Frontier Fields survey.”

    Livermore and Finkelstein have used the new method on two of the galaxy clusters in the Frontier Fields project: Abell 2744 and MACS 0416. It enabled them to identify faint galaxies seen when the universe was about a billion years old, less than 10 percent of its current age — galaxies 100 times fainter than those found in the Hubble Ultra Deep Field, for instance, which is the deepest image of the night sky yet obtained.

    Their observations showed that these faint galaxies are extremely numerous, consistent with the idea that large numbers of extremely faint galaxies were the main power source behind reionization.

    There are four Frontier Fields clusters left, and the team plans to study them all with Livermore’s method. In future, she said, they would like to use the James Webb Space Telescope to study even fainter galaxies.

    The work is published in a recent issue of The Astrophysical Journal.

    See the full article here .

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    U Texas Arlington Campus

    In 1839, the Congress of the Republic of Texas ordered that a site be set aside to meet the state’s higher education needs. After a series of delays over the next several decades, the state legislature reinvigorated the project in 1876, calling for the establishment of a “university of the first class.” Austin was selected as the site for the new university in 1881, and construction began on the original Main Building in November 1882. Less than one year later, on Sept. 15, 1883, The University of Texas at Austin opened with one building, eight professors, one proctor, and 221 students — and a mission to change the world. Today, UT Austin is a world-renowned higher education, research, and public service institution serving more than 51,000 students annually through 18 top-ranked colleges and schools.

  • richardmitnick 3:41 pm on September 28, 2016 Permalink | Reply
    Tags: , , Frontier Fields,   

    From Frontier Fields: “Beyond the Frontier Fields: How JWST Will Push the Science to a New Frontier” 

    Frontier Fields
    Frontier Fields

    September 28, 2016

    The Frontier Fields Project has been an ambitious campaign to see deep into our universe. Gravitational lensing, as used by the Frontier Fields Project, enables Hubble to see fainter and more-distant galaxies than would otherwise be possible. These images push to the very limits of how deeply Hubble can see out into space.

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    Hubble, Spitzer, Chandra, and other observatories are doing cutting-edge science through the Frontier Fields Project, but there’s a challenge.

    NASA/Spitzer Telescope
    NASA/Spitzer Telescope

    NASA/Chandra Telescope
    NASA/Chandra Telescope

    Even though leveraging gravitational lensing has allowed astronomers to see objects that otherwise could not be detected with today’s telescopes, the technique still isn’t enough to see the most distant galaxies. As the universe expands, light gets stretched into longer and longer wavelengths, beyond the visible and near-infrared wavelengths Hubble can detect. To see the most distant galaxies, one needs a space telescope with Hubble’s keen resolution, but at infrared wavelengths.

    That infrared telescope is the James Webb Space Telescope, slated to launch in October 2018. It has a mirror 6.5 meters (21 feet) across, can observe wavelengths up to 10 times longer than Hubble can observe, and is the mission that will detect and study the first appearances of galaxies in the universe.

    Figure 1: Webb will have a 6.5-meter-diameter primary mirror, which would give it a significant larger collecting area than the mirrors available on the current generation of space telescopes. Hubble’s mirror is a much smaller 2.4 meters in diameter, and its corresponding collecting area is 4.5 square meters, giving Webb around seven times more collecting area! Webb’s field of view is more than 15 times larger than the NICMOS near-infrared camera on Hubble. It also will have significantly better spatial resolution than is available with the infrared Spitzer Space Telescope. Credit: NASA. http://webbtelescope.org/gallery.

    Observations of the early universe are still incomplete. To build the full cosmological history of our universe, we need to see how the first stars and galaxies formed, and how those galaxies evolved into the grand structures we see today.

    Looking back in time to the first light in the universe:

    Astronomers use light to explore the universe, but there are pieces of our universe’s early history where there wasn’t much light. The era of the universe called the “Dark Ages” is as mysterious as its name implies. Shortly after the Big Bang, our universe was filled with glowing plasma, or ionized gas. As the universe cooled and expanded, electrons and protons began to bind together to form neutral hydrogen atoms (one proton and one electron each). The last of the light from the Big Bang escaped (becoming what we now detect as the Cosmic Microwave Background [CMB]).

    CMB per ESA/Planck
    CMB per ESA/Planck

    The universe would have been a dark place, with no sources of light to reveal this cooling, neutral hydrogen gas.

    Some of that gas would have begun coalescing into dense clumps, pulled together by gravity. As these clumps grew larger, they would become stars and eventually galaxies. Slowly, starlight would begin to shine in the universe. Eventually, as the early stars grew in numbers and brightness, they would have emitted enough ultraviolet light to “reionize” the universe by stripping electrons off neutral hydrogen atoms, leaving behind individual protons. This process created a hot plasma of free electrons and protons. At this point, the light from star and galaxy formation could travel freely across space and illuminate the universe. It is important to note here, astronomers are currently unsure whether the energy responsible for reionization came from stars in the early-forming galaxies; rather, it might have come from hot gas surrounding massive black holes or some even more exotic source such as decaying dark matter.

    The universe’s first stars, believed to be 30 to 300 times as massive as our Sun and millions of times as bright, would have burned for only a few million years before dying in tremendous explosions, or “supernovae.” These explosions spewed the recently manufactured chemical elements of stars outward into the universe before the expiring stars collapsed into black holes.

    Astronomers know the universe became reionized because when they look back at quasars — incredibly bright objects thought to be powered by supermassive black holes — in the distant universe, they don’t see the dimming of their light that would occur if the light passed through a fog of neutral hydrogen gas. While they find clouds of neutral hydrogen gas, they see almost no signs of neutral hydrogen gas in the matter located in the space between galaxies. This means that at some point the matter was reionized. Exactly when this occurred is one of the questions Webb will help answer, by looking for glimpses of very distant objects still dimmed by neutral hydrogen gas.

    Much remains to be uncovered about the time of reionization. The universe right after the Big Bang would have consisted of hydrogen, helium, and a small amount of lithium. But the stars we see today also contain heavier elements — elements that are created inside stars. So how did those first stars form from such limited ingredients? Webb may not be able to see the very first stars of the Dark Ages, but it’ll witness the generation of stars immediately following, and analyze the kinds of materials they contain.

    Webb’s ability to see the infrared light from the most distant objects in the universe will allow it to truly identify the sources that gave rise to reionization. For the first time, we will be able to see the stars and quasars that unleashed enough energy to illuminate the universe again.

    Figure 2: JWST will be able to see back to when the first bright objects (stars and galaxies) were forming in the early universe. Credit: STScI. http://jwst.nasa.gov/firstlight.html

    Early Galaxies:

    Webb will also show us how early galaxies formed from those first clumps of stars. Scientists suspect the black holes born from the explosions of the earliest stars (supernovae) devoured gas and stars around them, becoming the extremely bright objects called “mini-quasars.” The mini-quasars, in turn, may have grown and merged to become the huge black holes found in the centers of present-day galaxies. Webb will try to find and understand these supernovae and mini-quasars to put theories of early galaxy formation to the test. Do all early galaxies have these mini-quasars or only some? These regions give off infrared light as the gas around them cools, allowing Webb to glean information about how mini-quasars in the early universe work — how hot they are, for instance, and how dense.

    Webb will show us whether the first galaxies formed along lines and webs of dark matter, as expected, and when. Right now we know the first galaxies formed anywhere from 378,000 years to 1 billion years after the Big Bang. Many models have been created to explain which era gave rise to galaxies, but Webb will pinpoint the precise time period.

    Hubble is known for its deep-field images, which capture slices of the universe throughout time. But these images stop at the point beyond which Hubble’s vision cannot reach. Webb will fill in the gaps in these images, extending them back to the Dark Ages. Working together, Hubble and Webb will help us visualize much more of the universe than we ever have before, creating for us an unprecedented picture that stretches from the current day to the beginning of the recognizable universe.

    NASA/ESA/CSA Webb Telescope annotated
    NASA/ESA/CSA Webb Telescope annotated





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    Frontier Fields draws on the power of massive clusters of galaxies to unleash the full potential of the Hubble Space Telescope. The gravity of these clusters warps and magnifies the faint light of the distant galaxies behind them. Hubble captures the boosted light, revealing the farthest galaxies humanity has ever encountered, and giving us a glimpse of the cosmos to be unveiled by the James Webb Space Telescope.

    NASA Hubble Telescope
    NASA James Webb Telescope

  • richardmitnick 2:45 pm on September 28, 2016 Permalink | Reply
    Tags: Frontier Fields, , , , , The Frontier Fields: Where Primordial Galaxies Lurk   

    From JPL-Caltech: “The Frontier Fields: Where Primordial Galaxies Lurk” 

    NASA JPL Banner


    September 28, 2016
    Elizabeth Landau
    Jet Propulsion Laboratory, Pasadena, Calif.

    Written by Adam Hadhazy

    This image of galaxy cluster Abell 2744, also called Pandora’s Cluster, was taken by the Spitzer Space Telescope. The cluster is also being studied by NASA’s Hubble Space Telescope and Chandra X-Ray Observatory in a collaboration called the Frontier Fields project. Image credit:NASA/JPL-Caltech.

    NASA/Spitzer Telescope
    NASA/Spitzer Telescope

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    NASA/Chandra Telescope
    NASA/Chandra Telescope

    In the ongoing hunt for the universe’s earliest galaxies, NASA’s Spitzer Space Telescope has wrapped up its observations for the Frontier Fields project. This ambitious project has combined the power of all three of NASA’s Great Observatories — Spitzer, the Hubble Space Telescope and the Chandra X-ray Observatory — to delve as far back in time and space as current technology can allow.

    Even with today’s best telescopes, it is difficult to gather enough light from the very first galaxies, located more than 13 billion light years away, to learn much about them beyond their approximate distance. But scientists have a tool of cosmic proportions to help in their studies. The gravity exerted by massive, foreground clusters of galaxies bends and magnifies the light of faraway, background objects, in effect creating cosmic zoom lenses. This phenomenon is called gravitational lensing.

    The Frontier Fields observations have peered through the strongest zoom lenses available by targeting six of the most massive galaxy clusters known. These lenses can magnify tiny background galaxies by as much as a factor of one hundred. With Spitzer’s new Frontier Fields data, along with data from Chandra and Hubble, astronomers will learn unprecedented details about the earliest galaxies.

    “Spitzer has finished its Frontier Fields observations and we are very excited to get all of this data out to the astronomical community,” said Peter Capak, a research scientist with the NASA/JPL Spitzer Science Center at Caltech in Pasadena, California, and the Spitzer lead for the Frontier Fields project.

    A recent paper published in the journal Astronomy & Astrophysics presented the full catalog data for two of the six galaxy clusters studied by the Frontier Fields: Abell 2744 — nicknamed Pandora’s Cluster — and MACS J0416, both located about four billion light years away. The other galaxy clusters selected for Frontier Fields are RXC J2248, MACS J1149, MACS J0717 and Abell 370.

    Eager astronomers will comb the Frontier Fields catalogs for the tiniest, dimmest-lensed objects, many of which should prove to be the most distant galaxies ever glimpsed. The current record-holder, a galaxy called GN-z11, was reported in March by Hubble researchers at the astonishing distance of 13.4 billion light-years, only a few hundred million years after the big bang. The discovery of this galaxy did not require gravitational lenses because it is an outlying, extremely bright object for its epoch. With the magnification boost provided by gravitational lenses, the Frontier Fields project will allow researchers to study typical objects at such incredible distances, painting a more accurate and complete picture of the universe’s earliest galaxies.

    Astronomers want to understand how these primeval galaxies arose, how their constituent mass developed into stars, and how these stars have enriched the galaxies with chemical elements fused in their thermonuclear furnaces. To learn about the origin and evolution of the earliest galaxies, which are quite faint, astronomers need to collect as much light as possible across a range of frequencies. With sufficient light from these galaxies, astronomers can perform spectroscopy, pulling out details about stars’ compositions, temperatures and their environments by examining the signatures of chemical elements imprinted in the light.

    “With the Frontier Fields approach,” said Capak, “the most remote and faintest galaxies are made bright enough for us to start to say some definite things about them, such as their star formation histories.”

    Because the universe has expanded over its 13.8-billion-year history, light from extremely distant objects has been stretched out, or redshifted, on its long journey to Earth. Optical light emitted by stars in the gravitational-lensed, background galaxies viewed in the Frontier Fields has therefore redshifted into infrared. Spitzer can use this infrared light to gauge the population sizes of stars in a galaxy, which in turn gives clues to the galaxy’s mass. Combining the light seen by Spitzer and Hubble allows astronomers to identify galaxies at the edge of the observable universe.

    Hubble, meanwhile, scans the Frontier Fields galaxy clusters in optical and near-infrared light, which has redshifted from ultraviolet light on its journey to Earth. Chandra, for its part, observes the foreground galaxy clusters in high-energy X-rays emitted by black holes and ambient hot gas. Along with Spitzer, the space telescopes size up the masses of the galaxy clusters, including their unseen but substantial dark matter content. Nailing down the clusters’ total mass is a critical step in quantifying the magnification and distortion they produce on background galaxies of interest. Recent multi-wavelength results in this vein from the Frontier Fields project regarding the MACS J0416 and MACS J0717 clusters were published in October 2015 and February 2016. These results also brought in radio wave observations from the Karl G. Jansky Very Large Array to see star-forming regions otherwise hidden by gas and dust.

    The Frontier Fields collaboration has inspired scientists involved in the effort as they look ahead to delving even deeper into the universe with the James Webb Space Telescope, which is planned for launch in 2018.

    “The Frontier Fields has been an entirely community-led project, which is different from the way many projects of this magnitude are typically pursued,” said Lisa Storrie-Lombardi of the Spitzer Science Center, also with the Frontier Fields project. “People have gotten together and really embraced Frontier Fields.”

    In addition to the six Frontier Fields galaxy clusters, Spitzer has done follow-up observations on other, slightly shallower fields Hubble has gazed into, expanding the overall number of cosmic regions where fairly deep observations have been taken. These additional fields will further serve as rich areas of investigation for Webb and future instruments.

    NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive, housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

    For more information about Spitzer, visit:



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    Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge [1], on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

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  • richardmitnick 11:06 pm on March 10, 2016 Permalink | Reply
    Tags: , , Frontier Fields,   

    From Chandra: “MACS J0416.1-2403 and MACS J0717.5+3745: Telescopes Combine to Push Frontier on Galaxy Clusters” 

    NASA Chandra Banner

    NASA Chandra Telescope

    NASA Chandra

    MACS J0416.1-2403 and MACS J0717.5+3745
    Credit X-ray: NASA/CXC/SAO/G.Ogrean et al.; Optical: NASA/STScI; Radio: NRAO/AUI/NSF
    Release Date March 10, 2016

    These two galaxy clusters are part of the “Frontier Fields” project that obtains long observations with multiple telescopes.

    Galaxy clusters are important because they are the largest structures in the Universe held together by gravity.

    Both of these objects are sites where multiple galaxy clusters are colliding.

    X-rays from Chandra reveal the massive amounts of hot gas that pervade each galaxy cluster.

    Galaxy clusters are enormous collections of hundreds or even thousands of galaxies and vast reservoirs of hot gas embedded in massive clouds of dark matter, invisible material that does not emit or absorb light but can be detected through its gravitational effects. These cosmic giants are not merely novelties of size or girth – rather they represent pathways to understanding how our entire universe evolved in the past and where it may be heading in the future.

    To learn more about clusters, including how they grow via collisions, astronomers have used some of the world’s most powerful telescopes, looking at different types of light. They have focused long observations with these telescopes on a half dozen galaxy clusters. The name for this galaxy cluster project is the Frontier Fields.

    Two of these Frontier Fields galaxy clusters, MACS J0416.1-2403 (abbreviated MACS J0416) and MACS J0717.5+3745 (MACS J0717 for short) are featured here in a pair of multi-wavelength images.

    Located about 4.3 billion light years from Earth, MACS J0416 is a pair of colliding galaxy clusters that will eventually combine to form an even bigger cluster. MACS J0717, one of the most complex and distorted galaxy clusters known, is the site of a collision between four clusters. It is located about 5.4 billion light years away from Earth.

    These new images of MACS J0416 and MACS J0717 contain data from three different telescopes: NASA’s Chandra X-ray Observatory (diffuse emission in blue), Hubble Space Telescope (red, green, and blue), and the NSF’s [NRAO] Jansky Very Large Array (diffuse emission in pink). Where the X-ray and radio emission overlap the image appears purple. Astronomers also used data from the the Giant Metrewave Radio Telescope [GMRT] in India in studying the properties of MACS J0416.

    NASA Hubble Telescope
    NASA/ESA Hubble


    Giant Metrewave Radio Telescope

    The Chandra data shows gas in the merging clusters with temperatures of millions of degrees. The optical data shows galaxies in the clusters and other, more distant, galaxies lying behind the clusters. Some of these background galaxies are highly distorted because of gravitational lensing, the bending of light by massive objects. This effect can also magnify the light from these objects, enabling astronomers to study background galaxies that would otherwise be too faint to detect. Finally, the structures in the radio data trace enormous shock waves and turbulence. The shocks are similar to sonic booms, generated by the mergers of the clusters.

    New results from multi-wavelength studies of MACS J0416 and MACS J0717, described in two separate papers, are included below.

    An open question for astronomers about MACS J0416 has been: are we seeing a collision in these clusters that is about to happen or one that has already taken place? Until recently, scientists have been unable to distinguish between these two explanations. Now, the combined data from these various telescopes is providing new answers.

    In MACS J0416 the dark matter (which leaves its gravitational imprint in the optical data) and the hot gas (detected by Chandra) line up well with each other. This suggests that the clusters have been caught before colliding. If the clusters were being observed after colliding the dark matter and hot gas should separate from each other, as seen in the famous colliding cluster system known as the Bullet Cluster.

    Bullet Cluster NASA Chandra NASA ESA Hubble
    Bullet Cluster. NASA/Chandra NASA/ESA Hubble

    The cluster in the upper left contains a compact core of hot gas, most easily seen in a specially processed image, and also shows evidence of a nearby cavity, or hole in the X-ray emitting gas. The presence of these structures also suggests that a major collision has not occurred recently, otherwise these features would likely have been disrupted. Finally, the lack of sharp structures in the radio image provides more evidence that a collision has not yet occurred.

    In the cluster located in the lower right, the observers have noted a sharp change in density on the southern edge of the cluster. This change in density is most likely caused by a collision between this cluster and a less massive structure located further to the lower right.

    In Jansky Very Large Array images of this cluster, seven gravitationally-lensed sources are observed, all point sources or sources that are barely larger than points. This makes MACS J0717 the cluster with the highest number of known lensed radio sources. Two of these lensed sources are also detected in the Chandra image. The authors are only aware of two other lensed X-ray sources behind a galaxy cluster.

    All of the lensed radio sources are galaxies located between 7.8 and 10.4 billion light years away from Earth. The brightness of the galaxies at radio wavelengths shows that they contain stars forming at high rates. Without the amplification by lensing, some of these radio sources would be too faint to detect with typical radio observations. The two lensed X-ray sources detected in the Chandra images are likely active galactic nuclei (AGN) at the center of galaxies. AGN are compact, luminous sources powered by gas heated to millions of degrees as it falls toward supermassive black holes. These two X-ray sources would have been detected without lensing but would have been two or three times fainter.

    The large arcs of radio emission in MACS J0717 are very different from those in MACS J0416 because of shock waves arising from the multiple collisions occurring in the former object. The X-ray emission in MACS J0717 has more clumps because there are four clusters violently colliding.

    Georgiana Ogrean, who was at Harvard-Smithsonian Center for Astrophysics while leading the work on MACS J0416 research, is currently at Stanford University. The paper describing these results was published in the October 20th, 2015 issue of the Astrophysical Journal and is available online. The research on MACS J0717 was led by Reinout van Weeren from the Harvard-Smithsonian Center for Astrophysics, and was published in the February 1st, 2016 issue of the Astrophysical Journal and is available online.

    See the full article here .

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    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

  • richardmitnick 3:59 pm on December 29, 2015 Permalink | Reply
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    From Frontier Fields: “How Hubble “Sees” Gravity” 

    Frontier Fields
    Frontier Fields

    December 29, 2015
    Dr. Frank Summers

    Gravity is the familiar force of nature responsible for the diverse motions of a baseball thrown high into the air, a planet orbiting a star, or a star orbiting within a galaxy. Astronomers have long observed such motions and deduced the amount of gravity, and therefore the amount of matter, present in the planet, star, or galaxy. When taken to the extreme, gravity can also create some intriguing visual effects that are well suited to Hubble’s high-resolution observations.

    [Albert] Einstein’s general theory of relativity expresses how very large mass concentrations distort the space around them. Light passing through that distorted space is re-directed, and can produce a variety of interesting imagery. The bending of light by gravity is similar to the bending of light by a glass lens, hence we call this effect “gravitational lensing”.

    An “Einstein Cross” gravitational lens.

    The simplest type of gravitational lensing is called “point source” lensing. There is a single concentration of matter at the center, such as the dense core of a galaxy. The light of a distant galaxy is re-directed around this core, often producing multiple images of the background galaxy (see the image above for an example). When the lensing approaches perfect symmetry, a complete or almost complete circle of light is produced, called an “Einstein ring”. Hubble observations have helped to greatly increase the number of Einstein rings known to astronomers.

    Gravitational lensing in galaxy cluster Abell 2218

    More complex gravitational lensing arises in observations of massive clusters of galaxies.

    Panoramic view of the entire near-infrared sky reveals the distribution of galaxies beyond the Milky Way. The image is derived from the 2MASS Extended Source Catalog (XSC)—more than 1.5 million galaxies, and the Point Source Catalog (PSC)–nearly 0.5 billion Milky Way stars. The galaxies are color coded by redshift (numbers in parentheses) obtained from the UGC, CfA, Tully NBGC, LCRS, 2dF, 6dFGS, and SDSS surveys (and from various observations compiled by the NASA Extragalactic Database), or photo-metrically deduced from the K band (2.2 μm). Blue/purple are the nearest sources (z < 0.01); green are at moderate distances (0.01 < z < 0.04) and red are the most distant sources that 2MASS resolves (0.04 < z < 0.1). The map is projected with an equal area Aitoff in the Galactic system (Milky Way at center).
    IPAC/Caltech, by Thomas Jarrett

    While the distribution of matter in a galaxy cluster generally does have a center, it is never perfectly circularly symmetric and is usually significantly lumpy. Background galaxies are lensed by the cluster with their images often appearing as short thin “lensed arcs” around the outskirts of the cluster. Hubble’s images of galaxy clusters, such as Abell 2218 (above) and Abell 1689, showed the large number and detailed distribution of these lensed images throughout massive galaxy clusters.

    These lensed images also act as probes of the matter distribution in the galaxy cluster. Astronomers can measure the motions of the galaxies within a cluster to determine the total amount of matter in the cluster. The result indicates that the most of the matter in a galaxy cluster is not in the visible galaxies, does not emit light, and is thus called dark matter. The distribution of lensed images reflects the distribution of all matter, both visible and dark. Hence, Hubble’s images of gravitational lensing have been used to create maps of dark matter in galaxy clusters.

    In turn, a map of the matter in a galaxy cluster helps provide better understanding and analysis of the gravitational lensed images. A model of the matter distribution can help identify multiple images of the same galaxy or be used to predict where the most distant galaxies are likely to appear in a galaxy cluster image. Astronomers work back and forth between the gravitational lenses and the cluster matter distribution to improve our understanding of both.

    Three lensed images of a distant galaxy seen through a cluster of galaxies.

    On top of it all, gravitational lenses extend Hubble’s view deeper into the universe. Very distant galaxies are very faint. Gravitational lensing not only distorts the image of a background galaxy, it can also amplify its light. Looking through a lensing galaxy cluster, Hubble can see fainter and more distant galaxies than otherwise possible. The Frontier Fields project has examined multiple galaxy clusters, measured their lensing and matter distribution, and identified a collection of these most distant galaxies.

    While the effects of normal gravity are measurable in the motions of objects, the effects of extreme gravity are visible in images of gravitational lensing. The diverse lensed images of crosses, rings, arcs, and more are both intriguing and informative. Gravitational lensing probes the distribution of matter in galaxies and clusters of galaxies, as well as enables observations of the distant universe. Hubble’s data will also provide a basis and guide for the future James Webb Space Telescope, whose infrared observations will push yet farther into the cosmos.

    A “smiley face” gravitational lens in a galaxy cluster.

    The distorted imagery of gravitational lensing often is likened to the distorted reflections of funhouse mirrors, but don’t take that comparison too far. Hubble’s images of gravitational lensing provide a wide range of serious science.

    See the full article here .

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    Frontier Fields draws on the power of massive clusters of galaxies to unleash the full potential of the Hubble Space Telescope. The gravity of these clusters warps and magnifies the faint light of the distant galaxies behind them. Hubble captures the boosted light, revealing the farthest galaxies humanity has ever encountered, and giving us a glimpse of the cosmos to be unveiled by the James Webb Space Telescope.

    NASA Hubble Telescope
    NASA James Webb Telescope

  • richardmitnick 9:21 am on October 22, 2015 Permalink | Reply
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    From EPFL: “Looking at the earliest galaxies” 

    EPFL bloc

    Ecole Polytechnique Federale Lausanne

    Nik Papageorgiou


    An international team of astronomers led by EPFL have discovered over 250 of the universe’s earliest galaxies. This sample includes the faintest and smallest of the first-generation dwarf galaxies to be discovered, and offers important clues about the nature of the early universe.

    Before light travelled across it, the universe was a dark place. For about a billion years after the Big Bang, the cosmos was cloaked in a thick fog of hydrogen gas that kept light trapped. But as early stars began to form, hydrogen began to clear through a process called reionization, letting light escape in all directions and turning the universe transparent. This event played a central role in the formation of the universe as we know it. Now, using observations from the Hubble Space Telescope, astronomers led by EPFL have “looked back in time” by discovering over 250 of the earliest dwarf galaxies, and have also determined that these were vital to reionization. The work will be published in the Astrophysical Journal.

    Hydrogen and early stars

    Reionization is a mystery in the scientific community. We do know that 400 million years after the Big Bang, the universe was still a very dark place. Protons and neutrons had combined into electrically charged, or ionized, atoms of hydrogen and helium. The ions began to attract electrons, and turned into electrically neutral atoms, creating a thick fog that kept light contained.

    Slowly, the first stars formed, likely 30-300 times bigger than our own Sun. Being young and huge, they burned bright and brief, exploding in supernovae. The energetic electromagnetic radiation (including ultraviolet light) they released reionized the neutral atoms of hydrogen, and the fog cleared, letting light could travel to the vast corners of the universe.

    Looking back

    An international team of astronomers led by Hakim Atek at EPFL’s Laboratory of Astrophysics, have discovered over 250 of the earliest galaxies, just 600-900 million years after the Big Bang. The researchers used observations by the Hubble Space Telescope to study the largest sample of the earliest dwarf, ultra-faint galaxies known.

    But though powerful, the Hubble was not all. The scientists also exploited a cosmic phenomenon known as “gravitational lensing”. Because space has been expanding since the Bing Bang, the oldest objects are further along the “outgoing” direction. Consequently, their light will also be very faint.

    The team used closer galaxy clusters as a “magnifying lens” to observe older and more distant ones. Being super-massive, the galaxy clusters can bend spacetime. This forms a “gravitational lens” that can magnify the light from other galaxies hiding far behind the clusters.

    The scientists studied images of three galaxy clusters taken as part of the Hubble Frontier Fields program, a three-year, 840-orbit programme that explores the most distant regions of space through gravitational lensing effects around six different galaxy clusters.

    “Clusters in the Frontier Fields act as powerful natural telescopes and unveil for us these faint dwarf galaxies that would otherwise be invisible,” says Jean-Paul Kneib, co-author of the study from EPFL.

    Some of the galaxies the team discovered formed just 600 million years after the Big Bang, according to Daniel Schaerer’s distance determinations from the University of Geneva. This makes them among the faintest of any other galaxy that Hubble has observed for this cosmic epoch. But the accumulated light that these dwarf galaxies emit because of their very large number, could have played a major role in reionization.

    By observing the ultraviolet light from the galaxies found in this study the astronomers were able to calculate if these were in fact some of the galaxies involved in reionizing hydrogen. The team’s analysis determined, for the first time with a degree of confidence, that the smallest and most abundant of the galaxies in the study were in fact vital in the universe-sculpting process. “The bright and massive galaxies alone are not enough to account for reionization,” says Hakim Atek. “We need to take into account the contribution of a more abundant population of faint dwarf galaxies.”

    The study highlights the impressive possibilities of the Frontier Fields program. Scientists are currently working with Hubble images on another three galaxy clusters, and more exciting findings lie ahead. “Hubble remains unrivalled in its ability to observe the most distant galaxies and the sheer depth of the Hubble Frontier Field data guarantees very precise understanding of the cluster magnification effect, allowing us to make discoveries like these,” says Mathilde Jauzac, a co-author of the study from Durham University and the University of KwaZulu-Natal.

    This work represents a collaboration of EPFL’s Laboratory of Astrophysics with the Observatoire de Lyon, Durham University, the University of KwaZulu-Natal, CNRS-Aix Marseille Université, Yale University, Observatoire de Genève – University of Geneva, CNRS-Institut de Recherche en Astrophysique et Planétologie, the University of Hawaii, and the University of Arizona. The projects was funded by the European Research Council (grants “Light on the Dark” and CALENDS), the Leverhulme Trust, the Science and Technology Facilities Council, the National Science Foundation, the Space Telescope Science Institute, and CNRS. The Hubble Space Telescope is a project of international cooperation between the ESA and NASA.


    Atek H, Richard J, Jauzac M, Kneib J-P, Natarajan P, Limousin M, Schaerer D, Jullo E, Ebeling H, Egami E, Clement B. Are Ultra-faint Galaxies at z=6−8 Responsible for Cosmic Reionization? Combined Constraints from the Hubble Frontier Fields Clusters And Parallels. Astrophysical Journal (Link to manuscript).

    See the full article here .

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    EPFL is Europe’s most cosmopolitan technical university. It receives students, professors and staff from over 120 nationalities. With both a Swiss and international calling, it is therefore guided by a constant wish to open up; its missions of teaching, research and partnership impact various circles: universities and engineering schools, developing and emerging countries, secondary schools and gymnasiums, industry and economy, political circles and the general public.

  • richardmitnick 8:53 am on January 24, 2015 Permalink | Reply
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    From Frontier Fields: “MACS J0416 Data is Complete” 

    Frontier Fields
    Frontier Fields

    January 21, 2015
    Tracy Vogel

    Observations of another Frontier Fields galaxy cluster and parallel field are complete. This time, we have new images for you of MACS J0416.1-2403. Here’s the galaxy cluster:


    And here is the parallel field:


    Beautiful, aren’t they? This is the second Frontier Fields cluster and parallel field to be fully imaged.

    Remember that to maximize scientific discovery, Hubble is using two of its instruments simultaneously to examine both the cluster and the parallel field, then observing the same areas again with the instruments switched.

    Hubble takes two sets of observations, called epochs, in order to thoroughly examine the two areas. During the first, Hubble spent 80 orbits with the Advanced Camera for Surveys (ACS) pointing at the main galaxy cluster, and Wide Field Camera 3 (WFC3) looking at the parallel field. ACS provides a visible-light view, and WFC3 adds near-infrared light.

    NASA Hubble ACS

    NASA Hubble WFC3

    During the second epoch, Hubble spent 70 orbits targeting WFC3 on the main cluster and ACS on the parallel field.

    Scientists are poring over the new data, and one result is already in. Expect to hear more about these observations in the near future.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Frontier Fields draws on the power of massive clusters of galaxies to unleash the full potential of the Hubble Space Telescope. The gravity of these clusters warps and magnifies the faint light of the distant galaxies behind them. Hubble captures the boosted light, revealing the farthest galaxies humanity has ever encountered, and giving us a glimpse of the cosmos to be unveiled by the James Webb Space Telescope.

    NASA Hubble Telescope
    NASA James Webb Telescope

  • richardmitnick 4:59 pm on December 9, 2014 Permalink | Reply
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    From Frontier Fields: “Mapping Mass in a Frontier Fields Cluster” 

    Frontier Fields
    Frontier Fields

    December 9, 2014
    Tracy Vogel

    The Frontier Fields project’s examination of galaxy cluster MACS J0416.1-2403 has led to a precise map that shows both the amount and distribution of matter in the cluster. MACS J0416.1-2403 has 160 trillion times the mass of the Sun in an area over 650,000 light-years across.

    The mass maps have a two-fold purpose: they identify the location of mass in the galaxy clusters, and by doing so make it easier to characterize lensed background galaxies.

    Mass map of galaxy cluster MCS J0416.1–2403
    The galaxy clusters under observation in Frontier Fields are so dense in mass that their gravity distorts and bends the light from the more-distant galaxies behind them, creating the magnifying effect known as gravitational lensing. Astronomers use the lensing effect to determine the location of concentrations of mass in the cluster, depicted here as a blue haze. Credit: ESA/Hubble, NASA, HST Frontier Fields

    Astronomers use the distortions of light caused by mass concentrations to pinpoint the distribution of mass within the cluster, including invisible dark matter. Weakly lensed background galaxies, visible in the outskirts of the cluster where less mass accumulates, may be stretched into slightly more elliptical shapes or transformed into smears of light. Strongly lensed galaxies, visible in the inner core of the cluster where greater concentrations of mass occur, can appear as sweeping arcs or rings, or even appear multiple times throughout the image. And as a dual benefit, as the clusters’ mass maps improve, it becomes easier to identify which galaxies are strongly lensed, and which galaxies are farther away.
    Stronger lensing produces greater distortions. Astronomers can work backwards from the distortions to pinpoint the greater concentrations of mass responsible for producing such altered images.

    Stronger lensing produces greater distortions. Astronomers can work backwards from the distortions to pinpoint the greater concentrations of mass responsible for producing such altered images. Credit: A. Feild (STScI)

    The depth of the Frontier Fields images allows astronomers to see extremely faint objects, including many more strongly lensed galaxies than seen in previous observations of the cluster. Hubble identified 51 new multiply imaged galaxies around this cluster, for instance, quadrupling the number found in previous surveys. Because the galaxies are multiples, that means almost 200 strongly lensed images appear in the new observations, allowing astronomers to produce a highly constrained map of the cluster’s mass, inclusive of both visible and dark matter.

    The dark matter aspect is particularly intriguing. Because these types of Frontier Fields analyses create extremely precise maps of the locations of dark matter, they provide the potential for testing the nature of dark matter. Learning where dark matter concentrates in massive galaxy clusters can give clues to how it behaves and changes. And as the mass maps become more precise, astronomers are better able to determine the distance of the lensed galaxies.

    In order to obtain a complete picture of MACS J0416.1-2403’s mass, astronomers will also need to include weak lensing measurements. Follow up observations will include further Frontier Fields imaging, as well as X-ray measurements of hot gas and spectroscopic redshifts to break down the total mass distribution into dark matter, gas, and stars.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Frontier Fields draws on the power of massive clusters of galaxies to unleash the full potential of the Hubble Space Telescope. The gravity of these clusters warps and magnifies the faint light of the distant galaxies behind them. Hubble captures the boosted light, revealing the farthest galaxies humanity has ever encountered, and giving us a glimpse of the cosmos to be unveiled by the James Webb Space Telescope.

    NASA Hubble Telescope
    NASA James Webb Telescope

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