Tagged: Cosmic microwave background Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 9:47 am on December 24, 2015 Permalink | Reply
    Tags: , Cosmic microwave background,   

    From ESA: “Polarisation of the Cosmic Microwave Background: zoom” 

    European Space Agency

    Credits: ESA and the Planck Collaboration

    A visualisation of the polarisation of the Cosmic Microwave Background, or CMB, as detected by ESA’s Planck satellite on a small patch of the sky measuring 20º across.

    CMB Planck ESA

    ESA Planck



    In this image, the colour scale represents temperature differences in the CMB, while the texture indicates the direction of the polarised light. The patterns seen in the texture are characteristic of ‘E-mode’ polarisation, which is the dominant type for the CMB.

    For the sake of illustration, both data sets have been filtered to show mostly the signal detected on scales around 5º on the sky. However, fluctuations in both the CMB temperature and polarisation are present and were observed by Planck also on larger as well as smaller angular scales.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition


    ESA50 Logo large

  • richardmitnick 7:52 pm on July 13, 2015 Permalink | Reply
    Tags: , , Cosmic microwave background,   

    From U Hawaii IFA: “A Cold Cosmic Mystery Solved: “ 

    U Hawaii

    University of Hawaii

    Institute for Astronomy

    U Hawaii Institute for Astonomy Mauna Kea
    IFA at Manua Kea

    April 20, 2015

    Dr. István Szapudi
    +1 808 956-6196

    Dr. András Kovács
    +34 93 176 3966

    Dr. Roy Gal
    +1 808-956-6235
    cell: +1 301-728-8637

    Ms. Louise Good
    Media Contact
    +1 808-381-2939

    Astronomers discover what might be the largest known structure in the universe that leaves its imprint on cosmic microwave background radiation.
    Synopsis: A very large cold spot that has been a mystery for over a decade can now be explained.


    Cosmic Background Radiation Planck
    CMB per ESA/Planck


    Now, a team of astronomers led by Dr. István Szapudi of the Institute for Astronomy at the University of Hawaii at Manoa may have found an explanation for the existence of the Cold Spot, which Szapudi says may be “the largest individual structure ever identified by humanity.”



    Using data from Hawaii’s Pan-STARRS1 (PS1) telescope located on Haleakala, Maui, and NASA’s Wide Field Survey Explorer (WISE) satellite, Szapudi’s team discovered a large supervoid, a vast region 1.8 billion light-years across, in which the density of galaxies is much lower than usual in the known universe.

    Pann-STARSR1 Telescope
    Pann-STARSR1 Telescope

    NASA Wise Telescope





    NASA WMAP satellite

    ESA Planck


    Dark Energy Icon
    Dark Energy Camera
    Dark Energy Survey and it DECam camera, built at FNAL and housed in the CTIO Victor M Blanco 4 meter telescope


    U Hawaii IFA just put up a bunch of older articles into RSS. This is one of the best.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    System Overview


    The 10 UH campuses and educational centers on six Hawaiian Islands provide unique opportunities for both learning and recreation.


  • richardmitnick 11:53 am on February 14, 2015 Permalink | Reply
    Tags: , , , Cosmic microwave background,   

    From Ethan Siegel: “How can we still see the Big Bang?” 

    Starts with a bang
    Starts with a Bang

    Feb 14, 2015
    Ethan Siegel

    If it happened billions of years ago, what’s it still doing here?


    Sometimes, the simplest questions make for the most profound answers, and give us the opportunity to really dig deep into how we view the fabric of the Universe itself. This week, after sifting through your questions and suggestions for our Ask Ethan column, I couldn’t pass up the spectacular but straightforward question of Joseph McFarland, who wants to know:

    Why do we continue to detect the cosmic background radiation?
    Is the fact that we continue to eternally see the cosmic background radiation billions of years after it was generated proof of either inflation, or that the universe must be curved back upon itself (i.e. that it is finite but unbounded)?
    Or if neither of these are requirements, then what are other explanations?

    I want you to think about the history of the Universe.

    Image credit: NASA / CXC / M.Weiss.

    In particular, I want you to think of why it’s such a remarkable thing that we do detect the Cosmic Microwave Background at all. The story starts at the moment of the Big Bang, or more specifically, at the hot Big Bang.


    The hot Big Bang refers to a time some 13.8 billion years ago, when the Universe first emerged from an inflationary state — one where all the energy in it was inherent to space itself — and got converted into matter, antimatter and radiation. We can think of this as inflation being a field that’s in an unstable state, like a ball at the top of a hill, that then rolls down that hill and into a valley.

    While the ball is at the top of the hill, space itself expands at an exponential rate. When the ball rolls into the valley, and starts oscillating back-and-forth, that energy-of-space gets converted into matter, antimatter and radiation: a process known as reheating.

    Image credit: E. Siegel. Inflation ends when the ball rolls into the valley.

    The Universe still continues to expand, but because it’s filled with matter, antimatter and radiation, it no longer maintains a very large expansion rate for long. The expansion rate is tied — in General Relativity — to the energy density of the Universe, or how much energy there is per-unit-volume.

    When all you had was energy inherent to space itself, as the Universe expanded, you simply made more empty space, and the energy density stayed the same. But now that you’ve got stuff in the Universe instead, it dilutes (and gets less dense) as the Universe expands. In the case of radiation, the wavelength of light also stretches, which is why the Universe not only gets less dense, it also cools as time goes on.

    Images credit: TAKE 27 LTD / Science Photo Library, via Nature {above], Chris Palma of Penn State / Chaisson and McMillan, Astronomy [below].

    As the Universe expands and cools, from an incredibly hot, dense, uniform, rapidly expanding state down to a cool, sparse, clumpy, slowly expanding state, a huge number of important events happen:

    The fundamental symmetries of nature that are restored at the highest energies become broken, giving rise to things like particle rest masses.
    The Universe gets cool enough so that photons stop spontaneously forming matter/antimatter pairs. The excess antimatter annihilates away, leaving only 1 matter particle per ~1,400,000,000 photons.
    The interaction strength and rate drops significantly enough that neutrinos stop interacting with everything else in the Universe.
    The photon temperature drops enough so that the first stable, atomic nuclei can form without immediately being blasted apart.
    The temperature drops even further — by about another factor of a million — so that neutral atoms can stably form.

    And after that, the overdense regions grow into stars, galaxies and clusters of galaxies, giving rise to the Universe we see today, all while the photon energy continues to drop thanks to the ongoing expansion.

    Image credit: NASA / GSFC, via http://cosmictimes.gsfc.nasa.gov/universemashup/archive/pages/expanding_universe.html

    That next-to-last step — the one about the atoms becoming neutral — is where the Cosmic Microwave Background (CMB) originates. Prior to that time, the atoms were all ionized, meaning that they were simply positively charged nuclei and free electrons, bathed in a sea of photons. But photons have an extremely large scattering cross-section with electrons, meaning that they bounced around a tremendous amount.

    It’s only when the Universe cooled enough to become neutral that photons stopped seeing free electrons and started seeing only neutral, stable atoms. Because neutral atoms only absorb photons at very particular frequencies, and most of the photons that exist are not at those frequencies, these atoms are effectively transparent to all the photons that exist in the Universe!

    Images credit: Amanda Yoho, of the ionized plasma [upper] before the CMB is emitted, followed by the transition to a neutral Universe [lower] that’s transparent to photons.

    But because the Universe has been expanding and cooling for so long, you can take our location in space and fix it, and recognize one disconcerting fact: all the light from the Big Bang in the regions surrounding our own has been passing us by, continuously, for 13.8 billion years.

    All the stars, galaxies, large-scale structure, gas clouds and cosmic voids located thousands, millions, billions or even tens of billions of light-years away saw their CMB light pass us by ages and ages ago.

    Image credit: Wikimedia Commons user Unmismoobjetivo; of a logarithmic view of the Universe as centered on the Earth.

    Yet — to the point of Joseph’s original question — we still see the CMB, which corresponds (today) to a surface that’s some 45.3 billion light-years away.

    The fact that we still see the CMB at all tells us something very important: the Big Bang happened everywhere at once in a region of space that’s at least 45.3 billion light-years in radius, as seen from our perspective.

    Image credit: NASA/WMAP SCIENCE TEAM.

    And the fact that the CMB is not only visible in all directions, but is of a uniform temperature in all directions tells us — in the context of an inflationary Universe — that the amount that the (observable) Universe inflated must have taken it from an initial size that was, at maximum, 10^-29 meters (or less than a trillionth of 1% the size of a proton) and grew it by at least a factor of 10,000,000,000,000,000,000,000.

    The part of the Universe that we see, today, as our observable Universe could have been even smaller than that scale of 10^-29 meters, initially, and the amount that inflation grew that initial patch of space could have been arbitrarily larger than the factor of 10^22; there is no upper limit on that.

    Image credit: ESA and the Planck collaboration.

    So when we look at the Cosmic Microwave Background, at its uniformity and its small-scale, low-magnitude fluctuations, and the fact that there are no regions of it that are identifiable with one another (i.e., that the Universe does not exhibit a closed topology), we can conclude from this alone that the Big Bang must have occurred everywhere at once in a large region as viewed from our perspective.

    In the context of inflation — something we know an awful lot about — this gives us a lower bound as to the duration and scope of inflation, and ties it in to our observable Universe. The reason the CMB is still around is because the Big Bang, which itself came about at the end of inflation, happened over an incredibly large region of space, a region that’s at least as large as where we observe the CMB to still be. In all probability, that true region is much larger, and that not only will observers anywhere in the Universe see roughly the same CMB, but that we’ll continue to see it (albeit, redshifted a little farther) arbitrarily far into the future.

    Images credit: Wikimedia Commons users Theresa Knott and chris 論, modified by me (L); NASA / COBE science team (R), DMR (top) and FIRAS (bottom).

    Thanks for a great question, Joseph, and thanks to all of you for sending in a great selection of questions and suggestions for Ask Ethan! The truths of the Universe are written on the face of the Universe itself, and we’re doing everything we can to uncover them!

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition


Compose new post
Next post/Next comment
Previous post/Previous comment
Show/Hide comments
Go to top
Go to login
Show/Hide help
shift + esc

Get every new post delivered to your Inbox.

Join 599 other followers

%d bloggers like this: