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  • richardmitnick 7:37 am on October 25, 2014 Permalink | Reply
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    From Frontier Fields: “First Galaxy Field Complete: Abell 2744″ 

    Frontier Fields
    Frontier Fields

    October 23, 2014
    Tony Darnell

    This past summer, the Hubble Frontier Fields team completed observations of the first cluster on its list: Abell 2744! The second set of observations — astronomers call them epochs — consisted of 70 orbits and marks the completion of the first Frontier Fields galaxy cluster. During this set, Hubble’s Advanced Camera for Surveys (ACS) was pointed at the main galaxy cluster and studied the visible-light portions of the spectrum, while the Wide Field Camera 3 (WFC3) looked at the parallel field in the infrared.

    NASA Hubble ACS
    ACS

    NASA Hubble WFC3
    WFC3

    Remember that Hubble will visit each field multiple times, with Hubble oriented such that one set of observations will point WFC3 at the cluster and ACS at a parallel field adjacent to the cluster (that’s one epoch). The telescope will then come back and do another set of observations with the cameras switched: ACS pointing at the cluster and WFC3 pointing to the parallel field (that’s the second one).

    The Frontier Fields team does this to allow for complete wavelength coverage in both infrared and visible light for the galaxy cluster and the parallel field.

    The first epoch, completed in November 2013, consisted of 87 orbits. This brings the total amount of time Hubble looked at this cluster to 157 orbits.

    a2744
    Final mosaic of the Frontier Fields galaxy cluster Abell 2744. This image is the culmination of both epochs totaling 157 Hubble orbits. The numbers prefixed with “F” are the Hubble filters used by the ACS and WFC3 cameras to take the image. The scale bar of 30″ is approximately 2% the angular size of the full moon as seen from Earth – very small! Credit: NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI)

    Final mosaic of the Frontier Fields galaxy cluster Abell 2744. This image is the culmination of both epochs totaling 157 Hubble orbits. The numbers prefixed with “F” are the Hubble filters used by the ACS and WFC3 cameras to take the image. The scale bar of 30″ is approximately 2% the angular size of the full moon as seen from Earth – very small!
    Credit: NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI)

    par
    Parallel field of Frontier Field Abell 2744

    This is the completed composite mosaic of the Parallel Fields observed with galaxy cluster Abell 2744.
    Credit: NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI)

    See? Epic! Er, I mean epoch.

    Once the second epoch was completed, some of the faintest galaxies ever seen were measured for the first time. Astronomers have been working on these images since their release, and we are anxiously awaiting to hear what they find.

    See the full article here.

    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.

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  • richardmitnick 10:58 am on July 24, 2014 Permalink | Reply
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    From NASA/ESA Hubble: “New mass map of a distant galaxy cluster is the most precise yet” 

    NASA Hubble Telescope

    Hubble

    24 July 2014
    Mathilde Jauzac
    Durham University, Institute for Computational Cosmology
    Durham, United Kingdom
    Tel: +33 6 52 67 15 39 (France)
    Cell: +44 7445 218614 (UK)
    Email: mathilde.jauzac@dur.ac.uk

    Jean-Paul Kneib
    École Polytechnique Fédérale de Lausanne, Observatoire de Sauverny
    Versoix, Switzerland
    Tel: +41 22 3792473
    Cell: +33 695 795 392
    Email: jean-paul.kneib@epfl.ch

    Stunning new observations from Frontier Fields

    Astronomers using the NASA/ESA Hubble Space Telescope have mapped the mass within a galaxy cluster more precisely than ever before. Created using observations from Hubble’s Frontier Fields observing programme, the map shows the amount and distribution of mass within MCS J0416.1–2403, a massive galaxy cluster found to be 160 trillion times the mass of the Sun. The detail in this mass map was made possible thanks to the unprecedented depth of data provided by new Hubble observations, and the cosmic phenomenon known as strong gravitational lensing.

    imasge

    Measuring the amount and distribution of mass within distant objects in the Universe can be very difficult. A trick often used by astronomers is to explore the contents of large clusters of galaxies by studying the gravitational effects they have on the light from very distant objects beyond them. This is one of the main goals of Hubble’s Frontier Fields, an ambitious observing programme scanning six different galaxy clusters — including MCS J0416.1–2403, the cluster shown in this stunning new image.

    Large clumps of mass in the Universe warp and distort the space-time around them. Acting like lenses, they appear to magnify and bend light that travels through them from more distant objects.

    Despite their large masses, the effect of galaxy clusters on their surroundings is usually quite minimal. For the most part they cause what is known as weak lensing, making even more distant sources appear as only slightly more elliptical or smeared across the sky. However, when the cluster is large and dense enough and the alignment of cluster and distant object is just right, the effects can be more dramatic. The images of normal galaxies can be transformed into rings and sweeping arcs of light, even appearing several times within the same image. This effect is known as strong lensing, and it is this phenomenon, seen around the six galaxy clusters targeted by the Frontier Fields programme, that has been used to map the mass distribution of MCS J0416.1–2403, using the new Hubble data.

    “The depth of the data lets us see very faint objects and has allowed us to identify more strongly lensed galaxies than ever before,” explains Mathilde Jauzac of Durham University, UK, and Astrophysics & Cosmology Research Unit, South Africa, lead author of the new Frontier Fields paper. “Even though strong lensing magnifies the background galaxies they are still very far away and very faint. The depth of these data means that we can identify incredibly distant background galaxies. We now know of more than four times as many strongly lensed galaxies in the cluster than we did before.”

    Using Hubble’s Advanced Camera for Surveys, the astronomers identified 51 new multiply imaged galaxies around the cluster, quadrupling the number found in previous surveys and bringing the grand total of lensed galaxies to 68. Because these galaxies are seen several times this equates to almost 200 individual strongly lensed images which can be seen across the frame. This effect has allowed Jauzac and her colleagues to calculate the distribution of visible and dark matter in the cluster and produce a highly constrained map of its mass.

    NASA Hubble ACS
    Hubble ACS

    “Although we’ve known how to map the mass of a cluster using strong lensing for more than twenty years, it’s taken a long time to get telescopes that can make sufficiently deep and sharp observations, and for our models to become sophisticated enough for us to map, in such unprecedented detail, a system as complicated as MCS J0416.1–2403,” says team member Jean-Paul Kneib.

    By studying 57 of the most reliably and clearly lensed galaxies, the astronomers modelled the mass of both normal and dark matter within MCS J0416.1-2403. “Our map is twice as good as any previous models of this cluster!” adds Jauzac.

    The total mass within MCS J0416.1-2403 — modelled to be over 650 000 light-years across — was found to be 160 trillion times the mass of the Sun. This measurement is several times more precise than any other cluster map, and is the most precise ever produced. By precisely pinpointing where the mass resides within clusters like this one, the astronomers are also measuring the warping of space-time with high precision.

    “Frontier Fields’ observations and gravitational lensing techniques have opened up a way to very precisely characterise distant objects — in this case a cluster so far away that its light has taken four and a half billion years to reach us,” adds Jean-Paul Kneib. “But, we will not stop here. To get a full picture of the mass we need to include weak lensing measurements too. Whilst it can only give a rough estimate of the inner core mass of a cluster, weak lensing provides valuable information about the mass surrounding the cluster core.”

    The team will continue to study the cluster using ultra-deep Hubble imaging and detailed strong and weak lensing information to map the outer regions of the cluster as well as its inner core, and will thus be able to detect substructures in the cluster’s surroundings. They will also take advantage of X-ray measurements of hot gas and spectroscopic redshifts to map the contents of the cluster, evaluating the respective contribution of dark matter, gas and stars [5].

    Combining these sources of data will further enhance the detail of this mass distribution map, showing it in 3D and including the relative velocities of the galaxies within it. This paves the way to understanding the history and evolution of this galaxy cluster.

    The results of the study will be published online in Monthly Notices of the Royal Astronomical Society on 24 July 2014.

    NASA’s Chandra X-ray Observatory was used to obtain X-ray measurements of hot gas in the cluster and ground based observatories provide the data needed to measure spectroscopic redshifts.

    NASA Chandra Telescope
    NASA/Chandra

    Frontier Fields Mast

    The international team of astronomers in this study consists of M. Jauzac (Durham University, UK and Astrophysics & Cosmology Research Unit, South Africa); B. Clement (University of Arizona, USA); M. Limousin (Laboratoire d’Astrophysique de Marseille, France and University of Copenhagen, Denmark); J. Richard (Université Lyon, France); E. Jullo (Laboratoire d’Astrophysique de Marseille, France); H. Ebeling (University of Hawaii, USA); H. Atek (Ecole Polytechnique Fédérale de Lausanne, Switzerland); J.-P. Kneib (Ecole Polytechnique Fédérale de Lausanne, Switzerland and Laboratoire d’Astrophysique de Marseille, France); K. Knowles (University of KwaZulu-Natal, South Africa); P. Natarajan (Yale University, USA); D. Eckert (University of Geneva, Switzerland); E. Egami (University of Arizona, USA); R. Massey (Durham University, UK); and M. Rexroth (Ecole Polytechnique Fédérale de Lausanne, Switzerland)

    See the full article, with notes, here.

    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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    • viswamjyoti 7:13 am on August 30, 2014 Permalink | Reply

      Sub;MCS J0416.1–2403
      Data is useful but in-adequate perception of Galaxy Cluster formations -ignore the cosmic function of the Universe.

      Like

  • richardmitnick 5:09 am on May 24, 2014 Permalink | Reply
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    From Frontier Fields: “Einstein’s Crazy Idea” 

    Frontier Fields
    Frontier Fields

    May 23, 2014
    Dr. Frank Summers

    General relativity is just plain weird.

    The basic idea of gravity we are taught in school comes from Isaac Newton’sPrincipia” in 1687. Gravity is a force exerted by objects with mass. The greater the mass, the greater the gravitational force. The larger the distance between objects, the lesser the force ( it decreases with the square of the distance). The gravity of the Sun pulls on Earth and holds it, along with the other planets, asteroids, comets, etc., in orbit.

    Not so, according to Albert Einstein in 1916. He came up with a completely new, and quite radical, alternative explanation.

    Einstein’s crazy idea is that the presence of mass warps the fabric of space around it. Then, that warped space controls the motion of other masses nearby. Newton’s idea of a gravitational force is thus replaced with four-dimensional space-time geometry. Planets orbiting around stars, and stars traveling through galaxies — these are space-time distortions moving within other space-time distortions. As one famous description puts it: mass tells space how to warp, while warped space tells mass how to move. Yeah, weird.

    On the face of it, Isaac and Albert are just describing the same phenomenon from two different points of view: the former sees a force, while the latter sees geometric distortions. And, since the algebraic equations of the gravitational force are so, so, so, so, so very much simpler than the tensor calculus of general relativity, why go to all the relativistic trouble?

    The answer is that there are certain situations, generally involving very large masses, where Newton’s gravity is demonstrably wrong. The most famous of these is the precession of the perihelion of Mercury.

    The orbit of Mercury is not fixed in space. Each time Mercury orbits the Sun, its orbit rotates by a minuscule amount. The position when Mercury is closest to the Sun, called perihelion, is used to measure this orbit rotation, called precession. While Newton’s gravity predicts a precession of the perihelion of Mercury, the measured value is significantly higher. This mismatch between prediction and observation is resolved by Einstein’s general relativity in that the warping of space at such a close distance to the Sun produces a slightly stronger precession than gravitational force.

    eclipse
    One of the original plates from the 1919 solar eclipse used to measure the effects of general relativity.

    The other famous demonstration of general relativity is the bending of light as it passes a massive object. Light rays also have their paths changed by passing through warped space. A total solar eclipse on May 29, 1919, served to test this effect. During the eclipse, astronomers could see stars whose light had passed close to the Sun. Their apparent position on the sky would be shifted from their normal position due to passage through the warped space around the Sun. By observing the precise positions of such stars both before and during the eclipse, astronomers measured the effects of general relativity. (See the image accompanying this post.)

    Those 1919 observations did much to confirm that this crazy idea of general relativity reflected the reality of the universe. We now have many tests of general relativity. Most are subtle and require significant explanation. However, there is one that is visually striking, and which is critical to the scientific underpinnings of the Frontier Fields project. I’ll address that in my next blog post.

    See the full article here.

    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.

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  • richardmitnick 8:37 am on May 14, 2014 Permalink | Reply
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    From Frontier Fields: “Frontier Fields Q&A: Redshift and Looking Back in Time” 

    Frontier Fields
    Frontier Fields

    May 13, 2014
    Tracy Vogel

    Q: What do you mean when you say you’re “seeing some of the earliest galaxies in the universe?” How does looking into deep space allow you to look back in time?

    The simple answer is that light travels and the universe is huge. Light travels very fast – 186,000 miles (300,000 km) per second, but it still has to move across the vast distances of space. Remember that for us to see anything – from the flash of a camera to the glow of a really distant galaxy, we have to wait for its light to strike our eyes.

    That camera flash shows in our vision instantaneously because it doesn’t have far to go. But distances in the cosmos are so vast that it takes light a long time to reach us. The light from our closest companion, the Moon, takes about 1.3 seconds to cross the 239,000 miles (390,000 km) between us. So when you look up at the sky, you don’t see the Moon as it currently is. You see it as it appeared 1.3 seconds ago.
    This is so 1.3 seconds ago. Credit: Luc Viatour, Wikimedia Commons

    moon
    This is so 1.3 seconds ago.
    Credit: Luc Viatour, Wikimedia Commons

    The greater the distances, the greater the time difference. Light from the Sun needs about 500 seconds, or about eight minutes, to reach us from 93,200 miles (150 million km) away. Light from Neptune needs about four hours to cross the solar system.

    We refer to these distances by the time it takes light to cross them. So Neptune is four light-hours away, and the Sun is 500 light-seconds away. Light from the next nearest star, however, needs four years to reach us across space. We say that star is four light-years away. The light we see from that star in today’s sky is also four years old. For galaxies, we’re talking millions to billions of light years. So we see the farthest galaxies as they appeared in the early universe, because the light that left them way back then is finally reaching us just now.

    Q: What does it mean when you talk about a galaxy’s redshift?

    When we’re discussing the Frontier Fields project, we’re talking about something more precisely called “cosmological redshift.” The space light is traveling through is expanding. That means that the light wave gets stretched as it travels, like a spring being pulled into a different shape. This stretching shifts light into longer wavelengths.

    redshft
    Since red light has a longer wavelength than blue light, the light is said to be “red-shifted.” Credit: NASA

    The farthest galaxies in the universe would have originally emitted visible and ultraviolet light, but since that light has been stretched as it travels, those galaxies appear to us instead in the form of infrared light. Cosmological redshift refers to that change and the measure of that change.

    Q: Why do we hear the Frontier Fields galaxies described in terms of redshift and light-years? Which is right?

    They tell us different things. Light-years are a measurement of distance defined by the time it takes light to travel in a year. But distance is notoriously difficult to measure in astronomy.

    Cosmological redshift is a direct measurement of the expansion of space. Astronomers describe galaxies in terms of their redshift because unlike distance, it’s a clear and definite value that’s relatively easy to measure without many errors.

    Astronomers have different models of how the universe works, and they can plug the redshift into those models to get the distance to a galaxy – but the distance will differ depending on which model of the universe they use. The variations in those models include things like the shape of the universe, the rate at which it’s expanding, the amount of normal matter it contains, etc.

    Astronomy is about figuring out how the universe works and narrowing down all those models to the best one, and we still have a long way to go. Projects like Frontier Fields will help us rule out those models that don’t fit the incoming data.

    Q: Everywhere we look with the Frontier Fields project, galaxies appear to be moving away from us. Does this mean we’re in the center of the universe?

    No. It’s evidence that space is expanding. The easiest way to visualize this is to imagine a balloon. If you cover the balloon with dots, and then inflate it, no matter which dot you pick to represent your position, all the other dots will appear to be moving away from it as the balloon expands. Imagine this happening in three dimensions instead of on a flat surface, and you can understand why it looks like other galaxies are rushing away.

    Q: So space is expanding and the light from the earliest galaxies has traveled over 13 billion years to reach us. If space is expanding, are those galaxies even farther away now?

    Yes. For nearby galaxies, the expansion doesn’t make much of a difference. But for galaxies extremely far away, the distance is significant. That’s because the farther away an object is, the more space there is between us and the object. That in turn means there’s more space to undergo expansion, so the objects appear to be moving away from us much faster. Light from the earliest galaxies may have traveled 13 billion years to reach us, but those galaxies could be around 45 billion light-years distant by now.

    Q: Does this mean the galaxies are moving faster than the speed of light?

    No. No object can travel through space faster than the speed of light. But the expansion of space itself is not so constrained – in fact, theories of the beginning of the universe visualize the initial expansion of the Big Bang happening with unthinkable speed. But because the speed of light is only so fast, there are galaxies in the distance whose light we cannot yet see. We call this the edge of the visible universe.

    Q: What’s out there, past the edge?

    drag
    Space dragons! Ok, probably not. Credit: Uranometria

    DRAGONS! SPACE DRAGONS! GIANT, COSMIC FIRE-BREATHING SPACE DRA– Ok, fine, probably not. Credit: Uranometria, Wikimedia Commons

    We expect more of the same, though this is still an open question that astronomers are researching and theorizing about. We’ve found we tend to see the same distribution of galaxies no matter which direction we look in the universe. If we were somehow transported to a galaxy on what, for Earth, is the edge of the visible universe, the border of the visible universe would move, but the universe would neither change nor look very different to us.

    See the full article here.

    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.

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  • richardmitnick 5:32 am on May 3, 2014 Permalink | Reply
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    From Frontier Fields: “What’s Really in a Frontier Fields Image?” 

    Frontier Fields
    Frontier Fields

    April 28, 2014
    Tracy Vogel

    What are we actually seeing when we look at one of the Frontier Fields images? The gravitational lensing that produces the strange, almost artistic-looking effects in the images — the streaks and blobs of light among glowing galaxies – is visually striking, but little of it falls into typical expectations of what we see when we look into the universe.

    abell 2744
    Archival image of the Abell 2744 cluster taken with Hubble’s visible light ACS instrument.
    Credit: NASA, ESA, and R. Dupke (Eureka Scientific, Inc.), et al.

    Let’s break it down by examining this image of galaxy cluster Abell 2744, also known as Pandora’s Cluster. Four separate galaxy clusters containing several hundred galaxies are colliding in this image, providing the vast amount of mass — both normal and, most importantly, dark matter — needed to create a gravitational lens. The galaxies’ mass warps space and brightens, distorts and magnifies the light of nearly 3,000 galaxies located much farther away, behind the cluster.

    For simplicity’s sake we’ve highlighted a representative sample of objects in the image. The highlighting therefore doesn’t capture every single object — just a handful of good examples.

    Stars

    In this image, the white circles enclose stars in our own Milky Way galaxy. The stars have a distinctive cross-shape created by light reflecting off the struts in the telescope. We call these diffraction spikes. These spikes only occur with bright, point-like objects, such as relatively nearby stars.

    box

    Foreground Galaxies

    The green circles here capture galaxies that reside in the space between us and the Abell 2744 galaxy cluster. These galaxies are not affected by the gravitational lens – only galaxies behind the cluster are distorted and magnified. If you look at them, you see that their shapes are generally sharp, distinctive and recognizable. There aren’t many of these galaxies – the Frontier Fields project deliberately sought out galaxy clusters that didn’t have a lot of other objects in the way of Hubble’s view.

    box2

    Cluster Galaxies

    The yellow circles enclose the galaxies of the Abell 2744 galaxy cluster. These galaxies vary a lot in size, from dwarf galaxies a thousandth of the mass of our Milky Way to monster-sized central galaxies up to 100 times more massive than the Milky Way. Since the clusters are colliding, these galaxies are interacting with one another – each galaxy’s gravity is affecting the other galaxies, though the galaxies that are closest to one another affect each other more strongly. Some galaxies contain greater concentrations of mass than others, and thus have stronger gravitational effects – and make for stronger gravitational lenses.

    box3

    As we go on, you’ll see that some of the lensed galaxies in this image appear less or more warped than others. This is because the distribution of the cluster’s mass is uneven, and thus the bending of space-time is uneven. Think of it as looking at objects at the bottom of a lake – the surface of the water is uneven, so some of the objects are more distorted than others.

    As a side note, astronomers can actually study the distortion created by gravitational lensing to get an idea of how mass – both visible matter and the invisible dark matter — is distributed within the Abell 2744 galaxy cluster.

    Strongly Lensed Galaxies

    Now you’re seeing galaxies that are behind Abell 2744, and affected by the cluster’s gravitational lens. The light of these blue-circled galaxies is shining through the cluster, and is clearly distorted in many cases. In fact, many of these galaxies look like lines, streaks and arcs. They’re often concentrated along the same lines, and many of them have similar color schemes – blue with red patches.

    box3

    Some of these objects are actually the exact same galaxy, because the gravitational lens breaks the image up, as though we were looking through a very strangely shaped piece of glass. This brings us to …

    Weakly Lensed Galaxies

    These magenta-circled objects are galaxies that are still behind the gravitational lens, but are not strongly distorted. You see distinctive galaxy shapes, like spirals. Their light is still being magnified and brightened, but they fall in an area where the bumpy pane of glass in our earlier metaphor is smooth. They are not as magnified as the strongly lensed galaxies.

    box5

    Distant Galaxies

    The tiny red specks circled here don’t look like much, but they’re actually some of the most intriguing objects in the image. These are the farthest and faintest of the galaxies being magnified by the gravitational lens. Their light could be reaching us from so far away that we see them as they appeared in the early universe – as far back as just millions of years after the Big Bang. (In a universe that’s 13.7 billion years old, that’s extremely far indeed.) One of these objects, Abell2744_Y1, is a candidate for being the most distant galaxy discovered in this image.

    bopx

    See the full article here.

    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.

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  • richardmitnick 5:15 pm on April 24, 2014 Permalink | Reply
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    From Frontier Fields: “What is Dark Matter?” 

    Frontier Fields

    Frontier Fields

    One of the most novel aspects of the Frontier Fields project is the innovative way in which the Hubble Space Telescope is being made more powerful — without adding a single piece of equipment or changing a single hardware component.

    NASA Hubble Telescope

    While Hubble itself isn’t altered physically in any way to allow us to peer farther than we ever have into the universe, these observations wouldn’t be possible without one crucial component: dark matter.

    Frontier Fields is turbocharging Hubble by looking at the distant universe through gravitational lenses that boost the signal from the feeble light of remote galaxies, essentially making Hubble a more powerful telescope.

    For the amateur astronomers out there, these gravity lenses are like adding a Barlow lens to the eyepiece of Hubble.

    What creates these gravitational lenses?

    Matter, and lots of it. Thanks to the theory of general relativity, we know that space-time is warped by stars, planets, galaxies, black holes — anything with mass. The light bends as it travels through this warped space-time.

    This is exactly what ordinary lenses in a telescope do with light: they bend it. Hence the term “gravitational lens.”

    In order to make a decent gravitational lens that will show you the most distant galaxies in the universe, you need lots of matter. Among the largest collections of matter in the universe are of galaxies. Hundreds of billions of stars all grouped together can bend a lot of space-time (and they do). What could be better?

    A lot of galaxies all grouped together, otherwise known as galaxy clusters.

    We’ve written before about the galaxy clusters that the Frontier Fields team will observe throughout the course of the survey. They were chosen because they made good gravitational lenses.

    But while the galaxies in these clusters do have lots of stars in them — hundreds of billions in each one – stars actually are not the major factor contributing to the bending of space-time around the clusters.

    The largest contributor to the creation of those gravitational lenses is something we can’t see, smell, taste, hear, touch or interact with in any way: dark matter.

    This stuff is all over the universe — in fact, there is five times more of it in the universe than there is ordinary matter. Everything we can see in the cosmos — stars, planets, comets, all life on Earth, anything that’s made up of atoms — constitutes roughly 5% of the total matter and energy in the universe. Dark matter makes up about 24%.
    matter
    Composition of matter in the universe. Credit: NASA

    It’s usually at this point the astute person starts asking, “If dark matter won’t interact with us in any way, how do we know it’s there?”

    The answer is simple enough. We know dark matter exists because we can see its effects on those things we can see. We were first tipped off to dark matter in the 1950′s by the motions of galaxies. We noticed that if we added all the mass of all the stars inside of galaxies, something wasn’t right. The galaxies didn’t rotate the way they should. Their motions suggested that something else had to be there mixed in all the stars we could see.

    What’s more, the galaxies that were gathered together into clusters were short on mass. If just the mass we could observe was all there was, the clusters would fly apart. There wasn’t enough observed mass to make them stay together.

    This stuff, whatever it was, was making galaxies rotate as if they had more matter than we could see and was also holding galaxy clusters together. In astronomy, we are used to investigating celestial objects by the light they emit, reflect, or block. We called this strange new discovery dark matter because it does not interact with light — though clearly it has a gravitational field we can detect.

    We’re starting to get pretty good at estimating where the dark matter is in galaxy clusters. We can even make maps of it. Here is a map of dark matter around the Abell 1689 cluster, home to thousands of galaxies and trillions of stars.
    abell 1689
    Dark matter in the massive galaxy cluster Abell 1689, located 2.2 billion light-years away. The cluster contains about 1,000 galaxies and trillions of stars. Hubble cannot see the dark matter directly. Astronomers inferred its location by analyzing the effect of gravitational lensing, where light from galaxies behind Abell 1689 is distorted by intervening matter within the cluster. Credit: NASA, ESA, and Z. Levay (STScI)

    Astronomers have gone so far as to map where most of the dark matter is in the universe. Here’s a graphic showing the distribution of dark matter in the universe.
    map
    This three-dimensional map offers a first look at the web-like large-scale distribution of dark matter. The map reveals a loose network of dark matter filaments, gradually collapsing under the relentless pull of gravity, and growing clumpier over time. Credit: NASA, ESA, and R. Massey (California Institute of Technology)

    Most astronomers believe that dark matter is concentrated in and around small clusters of galaxies.

    For the purposes of the Frontier Fields Survey, dark matter plays a crucial role. Without it, these galaxy clusters would have less mass, and space-time would bend less significantly, creating a weaker lens. By using these powerful natural lenses, the Frontier Fields project will enable Hubble to see galaxies about 10 times deeper than the Ultra Deep Field, the current record holder for the deepest image ever taken.

    And that corresponds to 40 billion times fainter than what the human eye can see.

    Now the next question you may be asking is, “What’s this dark matter stuff made of?” Astronomers are actively researching that question, but that’s a post for another day — so stay tuned!

    See the full article here.

    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
    Hubble
    NASA James Webb Telescope
    Webb

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  • richardmitnick 4:02 am on April 12, 2014 Permalink | Reply
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    From Frontier Fields: “Hubble Observations: From the Ground to Your Computer” 

    Frontier Fields

    April 11, 2014
    Ann Jenkins

    This post is the second in a two-part series.

    In my last post, Hubble Observations: From the Sky to the Ground*, I wrote about the route Hubble images take as they are digitally transferred from space to the ground.

    This is the story of what happens after that data makes the 30-mile trip over land-lines from NASA’s Goddard Space Flight Center in Greenbelt, Md., to the Space Telescope Science Institute in Baltimore, Md., and ultimately to your computer as iconic Hubble pictures.

    Hubble generates approximately 855 gigabytes of new science data each month. That’s the equivalent of an 8,550-yard-long shelf of books. Astronomers, in turn, typically download six terabytes of data monthly from this growing archive. That would be the equivalent of the printed paper from 300,000 trees. By the beginning of April 2014, Hubble data had been used to publish more than 12,000 peer-reviewed scientific papers.

    The raw Frontier Fields data are available to the public immediately from a repository called the Barbara A. Mikulski Archive for Space Telescopes, or MAST. However, these data are not the beautiful, color Hubble images we have come to know and love. Raw images from the telescope are black and white, and include distortions introduced by the instruments, as well other unwanted artifacts from Earthshine, occasional Earth-orbiting satellite trails, bad pixels, and random hits by small, charged particles called cosmic rays.

    ray
    Cosmic ray signatures are removed by combining two exposures in a way that removes everything not in both images. Credit: NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, the HFF Team, and Ann Feild (STScI).

    It takes a team of about a dozen instrument analysts to “clean” these images by removing the distortions and artifacts. The refined images are posted once a week on MAST. These are the combination of multiple exposures taken in seven different filters, which allow light at specific wavelengths to enter the instruments.

    Hubble’s instruments have many filters. The Frontier Fields observations use four in infrared from the Wide Field Camera 3 (WFC3), and three in visible light from the Advanced Camera for Surveys (ACS). The final, deep, combined color image for each Frontier Field will have a total of 560 exposures, divided evenly between the main cluster and its parallel field.

    NASA Hubble WFC3
    WFC3

    NASA Hubble ACS
    ACS

    To produce a color picture, exposures from the seven filters are assigned the three primary colors of blue, green, and red based on their wavelengths. Images from the shortest, bluest wavelengths are assigned to blue, while images from the longest, reddest wavelengths are assigned to red, and intermediate wavelengths are assigned to green. These primary color images are then composited to produce the full-color picture so familiar to Hubble followers.

    filters
    The top row shows the combined exposures through each of the seven filters as single images. To produce the color pictures, exposures from several selected filters from Hubble’s WFC3 and ACS were combined into one of three primary colors based on their wavelengths. The primary color images were then composited to produce the full-color image. Credit: NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, the HFF Team, and Ann Feild (STScI).

    *My post

    See the full article here.

    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
    Hubble
    NASA James Webb Telescope
    Webb

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  • richardmitnick 4:54 pm on April 4, 2014 Permalink | Reply
    Tags: , , , , Frontier Fields,   

    From Frontier Fields: :”Hubble Observations: From the Sky to the Ground” 

    Frontier Fields

    April 1, 2014
    Ann Jenkins

    This post is part one in a two-part series.

    How does what Hubble sees become what you see? The first part involves moving science data from the sky to the ground—a complicated matter.

    When Hubble views an astronomical target, the digital information from that observation is stored onboard the telescope’s solid-state data recorders. The telescope records all of its science data to prevent any possible loss of unique information. Hubble’s flight operations team at Goddard Space Flight Center, in Greenbelt, Maryland manages the content of these recorders.

    NASA Hubble Telescope
    NASA/ESA Hubble in all of its glory

    Four antennae aboard Hubble send and receive information between the telescope and the ground. To communicate with the flight operations team, Hubble uses a group of NASA satellites called the Tracking and Data Relay Satellite System (TDRSS). Located in various positions across the sky, the TDRSS satellites provide nearly continuous communications coverage with Hubble.

    Hubble’s operators periodically transmit the data from Hubble through TDRSS to TDRSS’s ground terminal at White Sands, New Mexico. From there, the data are sent via landline to Goddard to ensure their completeness and accuracy.

    Goddard then transfers the data over landlines to the Space Telescope Science Institute in Baltimore, Maryland for processing, calibration, and archiving. There, they are translated into scientific information, such as wavelength and brightness, and ultimately into the iconic images that have become the hallmark of Hubble.

    We’ll discuss how those images are made in a future post.

    flow

    Image Credit: Ann Feild, STScI

    See the full article here.

    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
    Hubble
    NASA James Webb Telescope
    Webb

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  • richardmitnick 8:46 pm on April 2, 2014 Permalink | Reply
    Tags: , , , , Frontier Fields,   

    From NASA/Spitzer: “Spitzer Sees the Galactic Dawn with ‘Frontier Fields'” 



    Spitzer

    03.27.14
    No Writer Credit

    NASA’s Spitzer Space Telescope, in tandem with other major NASA observatories, has recently embarked on a major new mission to glimpse the universe’s very first galaxies. Called Frontier Fields, the project is a collaboration with the Hubble Space Telescope and the Chandra X-ray Observatory. All three telescopes, collectively known as NASA’s Great Observatories, are playing indispensable roles in this quest.

    NASA Frontier Fields

    NASA Hubble Telescope
    Hubble

    NASA Chandra Telescope
    Chandra

    The faintness of the earliest, most distant galaxies makes studying them a challenge. Frontier Fields, however, can spot these primordial galaxies courtesy of foreground clusters of galaxies, whose gargantuan mass and gravity form cosmic “zoom lenses.” Peering through these gravitational lenses is giving astronomers an unprecedented view of the galactic dawn.

    “Our overall science goal with the Frontier Fields is to understand how the first galaxies in the universe assembled,” said Peter Capak, a research scientist with the NASA/JPL Spitzer Science Center at the California Institute of Technology and the Spitzer lead for the Frontier Fields. “This pursuit is made possible by how massive galaxy clusters warp space around them, kind of like when you look through the bottom of a wine glass.”

    Although astronomers have relied on this cosmic lensing for many years now to turn up distant galactic quarry, Frontier Fields takes the practice to a new level. The project has selected the most massive and distant clusters on record, thus offering the highest magnification and deepest probe of the early universe available.

    Plus, Frontier Fields will further characterize the foreground clusters to better gauge the lenses’ magnifying, as well as distorting, effects. On average, the gravitational warping of space by foreground clusters magnifies background galaxies four to ten times. But some galaxies studied via Frontier Fields will be magnified on the order of a hundred times.

    NASA’s Great Observatories will view the cluster galaxies and background galaxies in different wavelengths of light, each of which carries important scientific information. Spitzer observes in longer wavelength, infrared light; Hubble, in shorter infrared and optical light; and Chandra in high-energy X-rays.

    The infrared light captured by Spitzer serves two key purposes. Firstly, infrared light is an indicator of the number of stars in a galaxy, which speaks to the galaxy’s overall mass. In the case of extremely distant galaxies, the optical light from their stars has been stretched out, or “redshifted,” into infrared wavelengths as a result of the expansion of the universe. “Spitzer basically measures the mass of galaxies,” said Capak. “Because of the wavelengths it works in, Spitzer is the only instrument capable of making mass measurements of galaxies this far away.”

    Secondly, Spitzer can help determine if certain galaxies also observed by Hubble are in fact the far-off, early galaxies of interest or just nearby galaxies. “Spitzer and Hubble can tell if galaxies discovered in the Frontier Fields are really at the edge of the universe or not,” said Capak.

    Hubble and Spitzer scientists envisioned this sort of synergy when the Frontier Fields were conceived in 2012. “This program exemplifies the combined strength of NASA’s Great Observatories when it comes to digging deep into the distant universe,” said Jennifer Lotz from the Space Telescope Science Institute, which manages Hubble for NASA.

    Chandra’s role in Frontier Fields, meanwhile, is to provide a detailed map of the hot, X-ray-emitting gas in the galaxy clusters. Doing so will help to further pin down their masses. Spitzer will be integral to this aspect of the project as well by presenting astronomers with an overview of the stars in the clusters’ galaxies.

    Observations of the first Frontier Field cluster, Abell 2744, have been completed. Work is now underway on another cluster and two more are slated for summer. The Abell 2744 effort has already resulted in the discovery of one of the most distant galaxies ever seen, dubbed Abell2744 Y1. This tiny, infant galaxy was witnessed at a time when the 13.8 billion-year-old universe was a mere 650 million years old. Frontier Fields is expected to reveal many other similarly primeval galaxies in the critical galaxy-forming epoch shortly after the Big Bang.

    Abell 2744
    NASA, ESA, J. Merten (Institute for Theoretical Astrophysics, Heidelberg/Astronomical Observatory of Bologna), and D. Coe (STScI)
    Date 22 June 2011
    Abell 2744, nicknamed Pandora’s Cluster. The galaxies in the cluster make up less than five percent of its mass. The gas (around 20 percent) is so hot that it shines only in X-rays (coloured red in this image). The distribution of invisible dark matter (making up around 75 percent of the cluster’s mass) is coloured here in blue.

    See the full article here.

    The Spitzer Space Telescope is a NASA mission managed by the Jet Propulsion Laboratory located on the campus of the California Institute of Technology and part of NASA’s Infrared Processing and Analysis Center.
    i1 i2


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  • richardmitnick 5:54 pm on March 28, 2014 Permalink | Reply
    Tags: , , , , Frontier Fields,   

    From Frontier Fields: “How Were the Galaxy Clusters Chosen?” 

    Frontier Fields

    March 28, 2014
    Dr. Brandon Lawton

    The 12 Frontier Fields will greatly expand upon our knowledge of the earliest galaxies to form in the universe. These images of the distant universe (in space and time), will provide us with a sneak peek at the first billion years of the universe. So how were these fields chosen?

    The Frontier Fields program was sketched out by the Frontier Fields team in the earliest phases of a recommendation process. Much can change in the process of going from an initial recommendation to a final program. The final program hinged upon finding the best galaxy clusters to anchor the Frontier Fields program. Team members deliberated between several different galaxy clusters, nominated by both those directly involved in the program and the broader astronomical community, before settling on the final candidates.

    Special consideration was given to galaxy clusters that
    maximize magnification and fit within Hubble’s view;
    were located in “clean” locations on the sky;
    were observable by ground-based observatories in the Northern and Southern hemispheres.

    The Frontier Fields team, with input from the broader astronomical community, was able to narrow down the galaxy cluster candidates to the six chosen for the program. Although it was not possible to select six clusters that met all of the criteria, most of the clusters satisfied most of the criteria. Let us explore the three criteria in a little bit more depth.

    Maximize Magnification

    Astronomers focused on massive galaxy clusters as candidates because the gravitational lenses they create are likely to provide the greatest magnification of background galaxies, but there were other considerations as well.

    Hubble is observing the Frontier Fields with a visible-light instrument and an infrared-light instrument. The fields of view of these instruments, defined to be the area of the sky they can image in one pointing, are relatively small – a box with sides about 1/15 the width of the full moon. Because of the small fields of view, the galaxy clusters need to be relatively compact so that any magnified background galaxy remains within the fields of view.

    The galaxy clusters must also be relatively compact in size. For each of the galaxy clusters, Hubble is also imaging an adjacent parallel field. For the goals of the program, the parallel fields need to contain unobstructed views of the early universe, devoid of the metropolis of galaxies that make up the galaxy clusters. Astronomers lose the magnifying power of the galaxy clusters, but gain simplicity. For the parallel fields, astronomers do not require detailed models of how the light from the distant galaxies are lensed by the foreground clusters.

    Clean Locations on the Sky

    Below is a map of the sky showing the locations of the six pointings required for Hubble to acquire the 12 Frontier Fields, labeled in order of when Hubble plans to observe them. The green labels are previous deep-field programs. The map is in right ascension and declination coordinates.

    For a map of the Frontier Fields on the sky, with respect to the constellations, see this previous post. Note: The right ascension of the map in the previous post is flipped with respect to the map below in order to portray the constellations as they appear to us on Earth.

    map

    This map shows the locations of the Frontier Fields on the sky using right ascension and declination coordinates. The Frontier Fields are numbered in the order of their observations. The colors denote the amount of extinction, or dimming, of light from distant galaxies due to foreground dust. Dark red denotes the greatest dust extinction. Dark blue denotes the least dust extinction. The wavy dust band across the sky is our Milky Way galaxy. The thick purple line is the ecliptic, which is the plane of our solar system. The two thinner parallel purple lines mark 30 degrees north and 30 degrees south of the ecliptic. Previous deep-field programs are labeled on the map in green: HDF-N (Hubble Deep Field North), HDF-S (Hubble Deep Field South), UDF (Ultra Deep Field), UDS (Ultra Deep Survey), COSMOS (the Cosmic Evolution Survey), and EGS (the Extended Groth Strip). Sgr A* denotes the position of the center of our Milky Way galaxy.
    Credit: D. Coe (STScI), D. Schlegel (LBNL), D. P. Finkbeiner (Harvard), M. Davis (Berkeley)

    The two main features to note on the above map are the colors that signify dust that can lessen the light from distant galaxies reaching Hubble’s mirror and the thick purple line that marks the plane of our solar system, known as the ecliptic. The locations of the Frontier Fields’ galaxy clusters were chosen to be in relatively “clean” parts of the sky. By that we mean that the galaxy clusters are not located where there is a large quantity of foreground dust.

    Dust Extinction

    The galaxy clusters in the Frontier Fields were chosen to avoid areas of greatest dust extinction. Dust extinction is the scattering or absorption of light by dust. It is problematic because it lessens the light we receive from distant objects. On the above map, dark red denotes areas of greatest dust extinction. Dark blue denotes little dust extinction. The red, high-extinction band in the all-sky map is due to the dusty disk of our own Milky Way galaxy. It appears wavy due to the projection of the sky onto the right ascension and declination coordinate system.

    Zodiacal Light

    The thick purple line denotes the plane of our solar system, called the ecliptic. Dust within our solar system is clustered around the ecliptic. This dust scatters the light from our Sun and produces a bright haze. It can be very difficult to observe faint objects through the zodiacal light. For this reason, the galaxy clusters were chosen to avoid the ecliptic.

    Observable from Telescopes across the Earth

    Much of what we learn from the Frontier Fields will come from follow-up observations using ground-based telescopes. Most of the galaxy clusters in the Frontier Fields are observable by state-of-the-art astronomical telescopes in both the Northern and Southern hemispheres. These include the new radio telescope in Chile, named ALMA, and the suite of telescopes on Mauna Kea in Hawaii.

    ALMA Array
    Atacama Large Millimeter/submillimeter Array (ALMA)

    Mauna Kea Observatories
    Mauna Kea Observatories

    See the full article here.

    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
    Hubble
    NASA James Webb Telescope
    Webb

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