Tagged: Gravitational Lensing Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 9:24 am on May 29, 2015 Permalink | Reply
    Tags: , , , Gravitational Lensing,   

    From FNAL- “Frontier Science Result: South Pole Telescope Gravitational lensing of the cosmic microwave background by galaxy clusters” 

    FNAL Home

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    May 29, 2015
    Scott Dodelson

    1
    The left panel shows a simulated map of an unlensed cosmic microwave background. The center panel shows the same map if a large galaxy cluster were along the line of sight. Note that the scale on these two panels goes to 100 microKelvin. The right panel shows the difference between the first two panels. The scale is now down to 10 microKelvin. (Plots are in units of arcminutes.) Image: Antony Lewis and Lindsay King, Institute of Astronomy

    The photons that make up the cosmic microwave background (CMB) have traversed the universe almost freely for 13.8 billion years, thereby carrying information about the state of the universe when it was only 380,000 years old.

    Cosmic Background Radiation Planck
    CMB per ESA/Planck

    ESA Planck
    ESA/Planck

    “Almost freely” refers to two ways that these photons are disturbed along their long journeys: They are sometimes scattered by hot electrons and they are deflected by deep gravitational wells.

    It is this latter deflection, called gravitational lensing, that offers immense promise as a tool to weigh massive objects such as galaxy clusters. Clusters are very important because their abundance offers insight into why the universe is currently accelerating. Extracting this insight, though, requires careful estimates of the masses of clusters. There are currently several techniques in play: X-ray emission, galaxy counts in the clusters, distortions of the shapes of background galaxies and the signal imprinted on the CMB by hot electrons in clusters.

    Lensing of the CMB provides a new way to measure cluster masses, one that has just been demonstrated. A simulated signal from one cluster is shown above. Each panel represents about 35 square arcminutes, about 20 times smaller than the moon, so a CMB experiment must have excellent resolution to see the effect. Cluster lensing is the difference between the left and center panels, shown in the right panel. The signal is roughly several microKelvin, much smaller than the typical hot and cold spots that have made the CMB famous. So the resolution must be coupled with exquisite sensitivity.

    Large ground-based telescopes such as the 10-meter South Pole Telescope [SPT] are beginning to attain this dual capability.

    South Pole Telescope
    SPT

    The noise levels are still too high to measure lensing by a single cluster, so the SPT team performed a likelihood analysis using 513 clusters, detected over three years of the telescope’s operation, to measure the weighted mass. The result was a 3-sigma measurement of the lensing of the CMB, with the mass consistent with those obtained with other methods. A paper on this result has recently been accepted for publication in The Astrophysical Journal.

    The team is now optimistic that this effect will lead to competitive constraints on cluster masses with upcoming surveys, such as SPT-3G and CMB-S4.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 2:54 pm on December 6, 2013 Permalink | Reply
    Tags: , , , , Gravitational Lensing, ,   

    From NASA/ESA Hubblecast 70: Gravitational Lensing 

    Watch Hubblecast 70 to learn about gravitational lensing.

    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.


    ESA Icon II


    ScienceSprings is powered by MAINGEAR computers

     
  • richardmitnick 12:33 pm on March 5, 2013 Permalink | Reply
    Tags: , , , , Gravitational Lensing   

    From NASA/ESA Hubble: “Gravitational telescope creates space invader mirage” 

    5 March 2013
    Nicola Guttridge
    Hubble/ESA
    Garching, Germany
    Tel: +49-89-3200-6855
    Email: nguttrid@partner.eso.org

    The NASA/ESA Hubble Space Telescope is one of the most powerful available to astronomers, but sometimes it too needs a helping hand. This comes in the form of Einstein’s general theory of relativity, which makes galaxy clusters act as natural lenses, amplifying the light coming from very distant galaxies.

    stellar

    Abell 68, pictured here in infrared light, is one of these galaxy clusters, and it greatly boosts the power of Hubble, extending the telescope’s ability to observe distant and faint objects [1]. The fuzzy collection of blobs in the middle and upper left of the image is a swarm of galaxies, each with hundreds of billions of stars and vast amounts of dark matter.

    The effect of this huge concentration of matter is to deform the fabric of spacetime, which in turn distorts the path that light takes when it travels through the cluster. For galaxies that are even further away than the cluster — which is already at the impressive distance of two billion light-years — and which are aligned just right, the effect is to turn galaxies that might otherwise be invisible into ones that can be observed with relative ease.

    Although the resulting images projected to us of these distant galaxies are typically heavily deformed, this process, called gravitational lensing, is a hugely valuable tool in cosmology, the branch of astronomy which deals with the origins and evolution of the Universe.

    [1] Hubble’s ability to see distant objects will be enhanced with the start of Frontier Fields in the near future, an observing campaign that aims to combine the power of Hubble with the natural gravitational telescopes of high-magnification clusters of galaxies — as seen here with Abell 68. This will enable Hubble to see objects that would ordinarily be too distant or faint for it to see. Frontier Fields will study six different galaxy clusters to give us a sneak preview of the very earliest stars and galaxies, before the launch of the James Webb Space Telescope in 2018.”

    See the full article 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.


    ESA Icon II


    ScienceSprings is powered by MAINGEAR computers

     
  • richardmitnick 3:24 pm on November 16, 2012 Permalink | Reply
    Tags: , , , , Gravitational Lensing, ,   

    From NASA: “NASA Great Observatories Find Candidate for Most Distant Galaxy Yet Known” 

    By combining the power of NASA’s Hubble Space Telescope, Spitzer Space Telescope, and one of nature’s own natural “zoom lenses” in space, astronomers have set a new distance record for finding the farthest galaxy yet seen in the universe.

    The diminutive blob, which is only a tiny fraction of the size of our Milky Way galaxy, offers a peek back into a time when the universe was 3 percent of its present age of 13.7 billion years. The newly discovered galaxy, named MACS0647-JD, is observed 420 million years after the big bang. Its light has traveled 13.3 billion years to reach Earth.

    image2

    This is the latest discovery from a large program that uses natural zoom lenses to reveal distant galaxies in the early universe. The Cluster Lensing And Supernova survey (CLASH) with Hubble is using massive galaxy clusters as cosmic telescopes to magnify distant galaxies behind them, an effect called gravitational lensing.

    Along the way, 8 billion years into its journey, this light took a detour along multiple paths around the massive galaxy cluster MACS J0647+7015. Due to the gravitational lensing, the CLASH research team, an international group led by Marc Postman of the Space Telescope Science Institute in Baltimore, Md., observed three magnified images of MACS0647-JD with the Hubble telescope. The cluster’s gravity boosted the light from the faraway galaxy, making the images appear approximately eight, seven, and two times brighter than they otherwise would, enabling astronomers to detect them more efficiently and with greater confidence. Without the cluster’s magnification powers, astronomers would not have seen this remote galaxy.

    ‘This cluster does what no manmade telescope can do,’ said Postman. ‘Without the magnification, it would require a Herculean effort to observe this galaxy.'”

    The object is so small it may be in the first embryonic steps of forming an entire galaxy. An analysis shows that the galaxy is less than 600 light-years wide. Based on observations of somewhat closer galaxies, astronomers estimate that a typical galaxy of that epoch should be about 2,000 light-years wide. For comparison, the Large Magellanic Cloud, a companion dwarf galaxy to the Milky Way, is 14,000 light-years wide. Our Milky Way is 150,000 light-years across.”

    Se the full article 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) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.


    ScienceSprings is powered by MAINGEAR computers

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
Follow

Get every new post delivered to your Inbox.

Join 447 other followers

%d bloggers like this: