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  • richardmitnick 7:55 am on February 21, 2017 Permalink | Reply
    Tags: , , , CMB, , , Magnetic mirror design for finding evidence of primordial gravitational waves   

    From ESA: “Magnetic mirror design for finding evidence of primordial gravitational waves” 

    ESA Space For Europe Banner

    European Space Agency

    20 February 2017
    No writer credit

    1
    Title Polarisation of the Cosmic Microwave Background: finer detail
    Released 05/02/2015 3:00 pm
    Copyright ESA and the Planck Collaboration
    Description

    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.

    The CMB is a snapshot of the oldest light in our Universe, imprinted on the sky when the Universe was just 380 000 years old. It shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure: the stars and galaxies of today.

    A small fraction of the CMB is polarised – it vibrates in a preferred direction. This is a result of the last encounter of this light with electrons, just before starting its cosmic journey. For this reason, the polarisation of the CMB retains information about the distribution of matter in the early Universe, and its pattern on the sky follows that of the tiny fluctuations observed in the temperature of the CMB.

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

    In this image, both data sets have been filtered to show mostly the signal detected on scales around 20 arcminutes on the sky. This shows the fine structure of the measurement obtained by Planck, revealing fluctuations in both the CMB temperature and polarisation on very small angular scales.

    ESA has backed the development of a ‘metamaterial’ device to sift through the faint afterglow of the Big Bang, to search for evidence of primordial gravitational waves triggered by the rapidly expanding newborn Universe.

    “This technological breakthrough widens the potential for a future follow-on to ESA’s 2009-launched Planck mission, which would significantly increase our detailed understanding of the Universe as it began,” explains Peter de Maagt, heading ESA’s Antennas and Sub-Millimetre Wave section.

    ESA/Planck
    ESA/Planck

    Planck mapped the ‘cosmic microwave background’ (CMB) – leftover light from the creation of the cosmos, subsequently redshifted to microwave wavelengths – across the deep sky in more detail than ever before.

    CMB per ESA/Planck
    CMB per ESA/Planck

    The CMB retains properties of ordinary light, including its tendency to polarise in differing directions – employed in everyday life by polarised sunglasses to cut out glare, or 3D glasses used to see alternating differently polarised cinema images through separate eyes.

    2
    Title Metamaterial-reflective half-wave plate
    Released 10/02/2017 4:16 pm
    Copyright Cardiff University
    Description

    Cardiff University’s magnetic mirror half-wave plate design for b-mode polarisation modulation across wide bandwidths. Less than 1 mm thick, this metamaterial-based design employs a combination of a grid-based ‘artificial magnetic conductor’ and metal ‘perfect electrical conductor’ surfaces. The overall effect is to create a differential phase-shift between orthogonal polarisations equal to 180 degrees. The rotation of the plate causes modulation of the polarisation signal.

    Researchers are now searching for one particular corkscrew polarisation of the CMB, known as ‘B-mode polarisation’, predicted to have been caused by gravitational waves rippling through the early Universe as it underwent exponential expansion – surging from a subatomic singularity to its current vastness.

    Identifying these theorised ‘stretchmarks’ within the CMB would offer solid proof that expansion did indeed occur, bringing cosmologists a big step closer to unifying the physics of the very large and the very small.

    “This would be the holy grail of cosmology,” comments Giampaolo Pisano of Cardiff University, heading the team that built the new prototype B-mode polarisation device for ESA.

    3
    The history of the Universe

    Into what is the universe expanding NASA Goddard, Dana Berry
    Into what is the universe expanding NASA Goddard, Dana Berry

    “Our contribution is only a small bit of the hugely complex instrument that will be necessary to accomplish such a detection. It won’t be easy, not least because it involves only a tiny fraction of the overall CMB radiation.”

    One of the main obstacles in detecting primordial B-modes is additional sources of polarisation located between Earth and the CMB, such as dust within our own galaxy.

    Such polarised foreground contributions have different spectral signatures to that of the CMB, however, enabling their removal if measurements are taken over a large frequency range.

    The challenge is therefore to devise a polarisation modulator that operates across a wide frequency bandwidth with high efficiency.

    “Our new ‘magnetic mirror’-based modulator can do just that, thanks to the quite new approach we adopted,” said Giampaolo Pisano.

    Polarisation modulation is often achieved with rotating ‘half-wave plates’. These induce the rotation of the polarised signals which can ‘stick out’ from the unpolarised background. However, the physical thickness of these devices defines their operational bandwidths, which cannot be too large.

    “Our new solution is based on a combination of metal grids embedded in a plastic substrate – what we call a ‘metamaterial’ – possessing customised electromagnetic properties not found in nature.

    “This flat surface transforms and reflects the signal back like a half-wave plate, facing none of the geometrical constraints of previous designs.”

    The team’s prototype multiband magnetic mirror polarisation modulator measures 20 cm across. Any post-Planck space mission would need one larger than a metre in diameter, its design qualified to survive the harsh space environment. The team are now working on enlarging it.

    “To come so far, the University of Cardiff team has had to develop all the equipment and engineering processes making it possible,” adds Peter. “Their work has been supported through ESA’s long-running Basic Technology Research Programme, serving to investigate promising new ideas to help enable future missions.”

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 1:11 pm on February 5, 2015 Permalink | Reply
    Tags: , , CMB,   

    From ESA: “Planck reveals first stars were born late” 

    ESASpaceForEuropeBanner
    European Space Agency

    5 February 2015
    Markus Bauer
    ESA Science and Robotic Exploration Communication Officer
    Tel: +31 71 565 6799; +34 91 8131 199
    Mob: +31 61 594 3954
    Email: Markus.Bauer@esa.int

    Jan Tauber
    ESA Planck Project Scientist
    Tel: +31 71 565 5342
    Email: Jan.Tauber@esa.int

    François Bouchet
    Institut d’Astrophysique de Paris (CNRS/UPMC), France
    Tel: +33 1 4432 8095
    Email: bouchet@iap.fr

    Marco Bersanelli
    Università degli Studi di Milano, Italy
    Tel: +39 02 50317264
    Email: marco.bersanelli@mi.infn.it

    George Efstathiou
    University of Cambridge, UK
    Tel: +44 1223 337530
    Email: gpe@ast.cam.ac.uk

    1
    Polarisation of the Cosmic Microwave Background

    5 February 2015

    New maps from ESA’s Planck satellite uncover the ‘polarised’ light from the early Universe across the entire sky, revealing that the first stars formed much later than previously thought.

    The history of our Universe is a 13.8 billion-year tale that scientists endeavour to read by studying the planets, asteroids, comets and other objects in our Solar System, and gathering light emitted by distant stars, galaxies and the matter spread between them.

    A major source of information used to piece together this story is the Cosmic Microwave Background, or CMB, the fossil light resulting from a time when the Universe was hot and dense, only 380 000 years after the Big Bang.

    Thanks to the expansion of the Universe, we see this light today covering the whole sky at microwave wavelengths.

    Between 2009 and 2013, Planck surveyed the sky to study this ancient light in unprecedented detail. Tiny differences in the background’s temperature trace regions of slightly different density in the early cosmos, representing the seeds of all future structure, the stars and galaxies of today.

    Scientists from the Planck collaboration have published the results from the analysis of these data in a large number of scientific papers over the past two years, confirming the standard cosmological picture of our Universe with ever greater accuracy.

    “But there is more: the CMB carries additional clues about our cosmic history that are encoded in its ‘polarisation’,” explains Jan Tauber, ESA’s Planck project scientist.

    “Planck has measured this signal for the first time at high resolution over the entire sky, producing the unique maps released today.”

    2
    History of the Universe

    Light is polarised when it vibrates in a preferred direction, something that may arise as a result of photons – the particles of light – bouncing off other particles. This is exactly what happened when the CMB originated in the early Universe.

    Initially, photons were trapped in a hot, dense soup of particles that, by the time the Universe was a few seconds old, consisted mainly of electrons, protons and neutrinos. Owing to the high density, electrons and photons collided with one another so frequently that light could not travel any significant distant before bumping into another electron, making the early Universe extremely ‘foggy’.

    Slowly but surely, as the cosmos expanded and cooled, photons and the other particles grew farther apart, and collisions became less frequent.

    This had two consequences: electrons and protons could finally combine and form neutral atoms without them being torn apart again by an incoming photon, and photons had enough room to travel, being no longer trapped in the cosmic fog.

    3
    CMB polarisation: full sky and details

    Once freed from the fog, the light was set on its cosmic journey that would take it all the way to the present day, where telescopes like Planck detect it as the CMB. But the light also retains a memory of its last encounter with the electrons, captured in its polarisation.

    “The polarisation of the CMB also shows minuscule fluctuations from one place to another across the sky: like the temperature fluctuations, these reflect the state of the cosmos at the time when light and matter parted company,” says François Bouchet of the Institut d’Astrophysique de Paris, France.

    “This provides a powerful tool to estimate in a new and independent way parameters such as the age of the Universe, its rate of expansion and its essential composition of normal matter, dark matter and dark energy.”

    Planck’s polarisation data confirm the details of the standard cosmological picture determined from its measurement of the CMB temperature fluctuations, but add an important new answer to a fundamental question: when were the first stars born?

    4
    CMB polarisation: zoom

    “After the CMB was released, the Universe was still very different from the one we live in today, and it took a long time until the first stars were able to form,” explains Marco Bersanelli of Università degli Studi di Milano, Italy.

    “Planck’s observations of the CMB polarisation now tell us that these ‘Dark Ages’ ended some 550 million years after the Big Bang – more than 100 million years later than previously thought.

    “While these 100 million years may seem negligible compared to the Universe’s age of almost 14 billion years, they make a significant difference when it comes to the formation of the first stars.”

    The Dark Ages ended as the first stars began to shine. And as their light interacted with gas in the Universe, more and more of the atoms were turned back into their constituent particles: electrons and protons.

    This key phase in the history of the cosmos is known as the ‘epoch of reionisation’.

    5
    CMB polarisation: finer detail

    The newly liberated electrons were once again able to collide with the light from the CMB, albeit much less frequently now that the Universe had significantly expanded. Nevertheless, just as they had 380 000 years after the Big Bang, these encounters between electrons and photons left a tell-tale imprint on the polarisation of the CMB.

    “From our measurements of the most distant galaxies and quasars, we know that the process of reionisation was complete by the time that the Universe was about 900 million years old,” says George Efstathiou of the University of Cambridge, UK.

    “But, at the moment, it is only with the CMB data that we can learn when this process began.”

    Planck’s new results are critical, because previous studies of the CMB polarisation seemed to point towards an earlier dawn of the first stars, placing the beginning of reionisation about 450 million years after the Big Bang.

    This posed a problem. Very deep images of the sky from the NASA–ESA Hubble Space Telescope have provided a census of the earliest known galaxies in the Universe, which started forming perhaps 300–400 million years after the Big Bang.

    However, these would not have been powerful enough to succeed at ending the Dark Ages within 450 million years.

    “In that case, we would have needed additional, more exotic sources of energy to explain the history of reionisation,” says Professor Efstathiou.

    The new evidence from Planck significantly reduces the problem, indicating that reionisation started later than previously believed, and that the earliest stars and galaxies alone might have been enough to drive it.

    This later end of the Dark Ages also implies that it might be easier to detect the very first generation of galaxies with the next generation of observatories, including the James Webb Space Telescope.

    NASA Webb Telescope
    NASA/Webb

    6
    Galactic dust

    But the first stars are definitely not the limit. With the new Planck data released today, scientists are also studying the polarisation of foreground emission from gas and dust in the Milky Way to analyse the structure of the Galactic magnetic field.

    The data have also enabled new important insights into the early cosmos and its components, including the intriguing dark matter and the elusive neutrinos, as described in papers also released today.

    The Planck data have delved into the even earlier history of the cosmos, all the way to inflation – the brief era of accelerated expansion that the Universe underwent when it was a tiny fraction of a second old. As the ultimate probe of this epoch, astronomers are looking for a signature of gravitational waves triggered by inflation and later imprinted on the polarisation of the CMB.

    No direct detection of this signal has yet been achieved, as reported last week. However, when combining the newest all-sky Planck data with those latest results, the limits on the amount of primordial gravitational waves are pushed even further down to achieve the best upper limits yet.

    “These are only a few highlights from the scrutiny of Planck’s observations of the CMB polarisation, which is revealing the sky and the Universe in a brand new way,” says Jan Tauber.

    “This is an incredibly rich data set and the harvest of discoveries has just begun.”

    See the full article here.

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 1:13 pm on January 18, 2015 Permalink | Reply
    Tags: , , CMB,   

    From ESA: “The magnetic field along the Galactic plane” 

    ESASpaceForEuropeBanner
    European Space Agency

    15/12/2014
    No Writer Credit

    1

    While the pastel tones and fine texture of this image may bring to mind brush strokes on an artist’s canvas, they are in fact a visualisation of data from ESA’s Planck satellite. The image portrays the interaction between interstellar dust in the Milky Way and the structure of our Galaxy’s magnetic field.

    ESA Planck
    Planck

    Between 2009 and 2013, Planck scanned the sky to detect the most ancient light in the history of the Universe – the cosmic microwave background. It also detected significant foreground emission from diffuse material in our Galaxy which, although a nuisance for cosmological studies, is extremely important for studying the birth of stars and other phenomena in the Milky Way.

    Cosmic Background Radiation Planck
    CMB per Planck

    Among the foreground sources at the wavelengths probed by Planck is cosmic dust, a minor but crucial component of the interstellar medium that pervades the Galaxy. Mainly gas, it is the raw material for stars to form.

    Interstellar clouds of gas and dust are also threaded by the Galaxy’s magnetic field, and dust grains tend to align their longest axis at right angles to the direction of the field. As a result, the light emitted by dust grains is partly ‘polarised’ – it vibrates in a preferred direction – and, as such, could be caught by the polarisation-sensitive detectors on Planck.

    Scientists in the Planck collaboration are using the polarised emission of interstellar dust to reconstruct the Galaxy’s magnetic field and study its role in the build-up of structure in the Milky Way, leading to star formation.

    In this image, the colour scale represents the total intensity of dust emission, revealing the structure of interstellar clouds in the Milky Way. The texture is based on measurements of the direction of the polarised light emitted by the dust, which in turn indicates the orientation of the magnetic field.

    This image shows the intricate link between the magnetic field and the structure of the interstellar medium along the plane of the Milky Way. In particular, the arrangement of the magnetic field is more ordered along the Galactic plane, where it follows the spiral structure of the Milky Way. Small clouds are seen just above and below the plane, where the magnetic field structure becomes less regular.

    From these and other similar observations, Planck scientists found that filamentary interstellar clouds are preferentially aligned with the direction of the ambient magnetic field, highlighting the strong role played by magnetism in galaxy evolution.

    The emission from dust is computed from a combination of Planck observations at 353, 545 and 857 GHz, whereas the direction of the magnetic field is based on Planck polarisation data at 353 GHz.

    See the full article here.

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 3:32 pm on December 15, 2014 Permalink | Reply
    Tags: , , , CMB, ,   

    From ESA: “The magnetic field along the Galactic plane” 

    ESASpaceForEuropeBanner
    European Space Agency

    15/12/2014

    ESA/Planck Collaboration

    i

    While the pastel tones and fine texture of this image may bring to mind brush strokes on an artist’s canvas, they are in fact a visualisation of data from ESA’s Planck satellite.

    ESA Planck
    ESA Planck schematic
    ESA/Planck

    The image portrays the interaction between interstellar dust in the Milky Way and the structure of our Galaxy’s magnetic field.

    Between 2009 and 2013, Planck scanned the sky to detect the most ancient light in the history of the Universe – the cosmic microwave background. It also detected significant foreground emission from diffuse material in our Galaxy which, although a nuisance for cosmological studies, is extremely important for studying the birth of stars and other phenomena in the Milky Way.

    Cosmic Microwave Background  Planck
    CMB per ESA/Planck

    Among the foreground sources at the wavelengths probed by Planck is cosmic dust, a minor but crucial component of the interstellar medium that pervades the Galaxy. Mainly gas, it is the raw material for stars to form.

    Interstellar clouds of gas and dust are also threaded by the Galaxy’s magnetic field, and dust grains tend to align their longest axis at right angles to the direction of the field. As a result, the light emitted by dust grains is partly ‘polarised’ – it vibrates in a preferred direction – and, as such, could be caught by the polarisation-sensitive detectors on Planck.

    Scientists in the Planck collaboration are using the polarised emission of interstellar dust to reconstruct the Galaxy’s magnetic field and study its role in the build-up of structure in the Milky Way, leading to star formation.

    In this image, the colour scale represents the total intensity of dust emission, revealing the structure of interstellar clouds in the Milky Way. The texture is based on measurements of the direction of the polarised light emitted by the dust, which in turn indicates the orientation of the magnetic field.

    This image shows the intricate link between the magnetic field and the structure of the interstellar medium along the plane of the Milky Way. In particular, the arrangement of the magnetic field is more ordered along the Galactic plane, where it follows the spiral structure of the Milky Way. Small clouds are seen just above and below the plane, where the magnetic field structure becomes less regular.

    From these and other similar observations, Planck scientists found that filamentary interstellar clouds are preferentially aligned with the direction of the ambient magnetic field, highlighting the strong role played by magnetism in galaxy evolution.

    The emission from dust is computed from a combination of Planck observations at 353, 545 and 857 GHz, whereas the direction of the magnetic field is based on Planck polarisation data at 353 GHz.

    Acknowledgment: M.-A. Miville-Deschênes, >CNRS – Institut d’Astrophysique Spatiale, Université Paris-XI, Orsay, France

    See the full article here.

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 5:42 pm on December 6, 2014 Permalink | Reply
    Tags: , , CMB, , , , Princeton SPIDER   

    From Princeton- ” SPIDER: Searching for the Echoes of Inflation” 

    Princeton University
    Princeton University

    Princeton SPIDER Inflation

    December 5, 2014
    Zigmund Kermish
    Zigmund Kermish is an associate research scholar at Princeton University.

    Wait, why am I in Antarctica?

    I realized I’ve not yet written a blog post explaining why my experiment is in Antarctica. Things are temporarily quiet on the Ice while we’ve been waiting for the SPIDER cryostat to cool down, so now’s a good time to make the attempt.

    To get the best results from SPIDER, we have to go to very high and dry locations. This is because water vapor in the atmosphere limits SPIDER’s sensitivity. There are currently two terrestrial locations that are commonly used: the Atacama Desert POLARBEAR and ACTPol
    sit at about 5,200 meters above sea level) and the South Pole (where the South Pole Telescope, the KECK array, and this year BICEP3 operate at 2,800 meters).

    POLARBEAR McGill Telescope
    POLARBEAR

    ACT Telescope
    Princeton Atacama Cosmology Telescope

    South Pole Telescope
    South Pole Telescope (SPT)

    Keck Array
    Keck Array

    BICEP 2
    BICEP 2 interior
    BICEP

    Of course, one can always go beyond terrestrial limits. With a big enough budget and enough time to develop the project, you can launch a dedicated satellite mission to eliminate the atmosphere all together, achieving dramatically improved individual detector sensitivities. Historically, satellite-based instruments have provided the definitive measurements of various aspects of the cosmic microwave background (the faint signal left over from the Big Bang), but they usually build upon the groundbreaking discoveries made closer to Earth. These discoveries have been made from the ground and from one other platform: balloons.

    Balloon-borne instruments have one big advantage: they allow us to get above nearly all of the atmosphere, approaching the detector sensitivity of satellite-based instruments at a fraction of the cost of a satellite mission.

    Princeton SPIDER instrument

    This increased detector sensitivity has two advantages: you can observe a larger fraction of the sky for a significantly shorter amount of time and still get a higher fidelity map than what you can do from the ground (observing for days rather than years) and you can observe in frequency channels that are difficult (if not impossible) to use from the ground. Both of these features, multiple frequencies and larger sky coverage, are necessary to ultimately demonstrate the ‘cosmological nature’ of the signals we’re looking for – to show that it’s not just a signal from some foreground in our local galaxy and that it has the required statistical properties across the sky we expect from proposed theories.

    As shown in the below gif, SPIDER can observe a large fraction of the ‘clean’ sky (the white outline) for 20 days and get nearly the same sensitivity over that region as a ground based experiment like the BICEP2 project had on their smaller region (green outline) after several years of observation.
    dust_regions

    g

    A map of the dust intensity seen in the sky, the bright center band the emission from our own Milky Way galaxy. The overlay that is fading in shows several things: The colored diamonds show the most recent data about the *polarization* strength of the dust signal, blue being less polarized dust, the outlines on the overlay show the regions observed (or to be observed shortly!) by BICEP2 (green), POLARBEAR (red), and SPIDER (white).

    Ok, so that’s why we want to dangle our instrument from a balloon. But why Antarctica? Why don’t we just launch our balloon from New Jersey?

    Well, for one, at some point, we need to bring the instrument back down to Earth, and that involves literally letting it fall to the ground so that we can recover it. That’s why scientific payload balloon flights only happen in places with low population density. In the US, payloads are flown out of Fort Sumner, New Mexico. They used to fly out of Palestine, Texas as well. Payloads flown out of these locations are limited to flights anywhere from a few hours to a few days because they eventually start getting too close to population centers.

    Antarctica doesn’t have any population centers, so rather than being limited by distance, flights are limited by how long the balloons can stay afloat. Currently, that’s about 40 days. Beyond that, weather patterns setup circumpolar winds during the austral summer here.

    So if you launch a balloon at the right time, it’ll come back close to where it started, making recovery of the instrument easier (it takes about a week to ‘boomerang’ back around). This is especially important for an experiment like ours since we need to physically recover our data off the drives that fly with the instrument. The bandwidth of in-flight communications limits us to only getting a small fraction of the data from the instrument during flight. One of the many ballooning challenges is to make the system as autonomous as possible so minimal human intervention based on the limited information we decide to ‘downlink’ to the ground is needed.

    The other fundamental challenges of ballooning that make this a very different game from ground-based experiments I’ve worked on: weight and power constraints. Having to fly the batteries you need to power the experiment, the solar panels to keep them charged, the cryogenic system to keep the everything cool and all the readout and control electronics systems while still staying below the maximum mass limits current balloons can float makes a project like this a fun problem to solve. The absence of day-night cycles during the austral summer in Antarctica helps address the power and weight constraints by giving us a continual source of solar power. This means we only need to fly a few heavy batteries to provide a non-variable power source and we can dedicate more of our mass budget to the scientific instruments. More compromises have to be made when designing payloads to fly at mid-latitudes, where enough batteries need to fly to power the payload throughout the night. There are many advantages to these mid-latitude flights though: larger available sky and longer (100 day!) flights with NASA’s new, soon-to-launch-with-science-payloads super pressure balloon platform (SPB).

    The CMB Cosmology group at Case is led by Prof. John Ruhl. The current members of our group are (GS = Graduate Student, UGS = Undergraduate Student):

    Tom Montroy (Senior Research Assoc.)
    Rick Bihary (Technician of Everything)
    Sean Bryan (GS, Spider)
    J.T. Sayre (GS, SPT)
    Ben Saliwanchik (GS, SPT)
    Adam Stohs (UGS)
    Dane Pittock (UGS)

    Phone numbers (all have 216 area code):

    Rock 117 lab: 368-1153
    Rock 117a lab: 368-3608
    Rock 117a fax: 368-0952
    Rock 114 lab and GS office: 368-2489
    Physics Student Shop: 368-3053
    Prof. Ruhl’s office: 368-4049

    We are located in Rockefeller Hall, on the main quad campus of Case Western Reserve University. Our shipping address is:

    Physics Dept, Rockefeller Hall
    Case Western Reserve University
    10900 Euclid Ave.
    Cleveland, OH 44106-7079

    Spider is a balloon-borne instrument designed to search for the signature of primordial gravity waves that is (hopefully) encoded in the polarization of the CMB. The design consists of six independent telescopes operating at three frequencies (100, 150, and 220GHz), with the optics cooled to 4 Kelvin and the bolometric detectors cooled to 0.25K.

    Gravitational Wave Background

    Spider’s first test flight will be in the fall of 2009, from Alice Springs, Australia. The test flight will be 2-4 nights duration, limited by the requirement that the balloon be brought down before it leaves the continent. The full “around the world” flight will be a year later, if all goes well.
    There are two publications describing Spider:

    “Spider Optimization: Probing the Systematics of a Large Scale B-Mode Experiment”, C. J. MacTavish etal, arXiv:0710.0375, submitted to ApJ. (This discusses Spider’s potential systematics and scan strategies).
    “SPIDER: a new balloon-borne experiment to measure CMB polarization on large angular scales”, T. E. Montroy etal, Proceedings of the SPIE, ed L. M. Step, v 6267, p62670R, (2006). (This describes the Spider instrument as originally conceived.)

    In addition to the effort at Case, the Spider collaboration includes groups at Caltech, JPL, U. Toronto, UBC, NIST, Cardiff, and the Imperial College of London. The main SPT website is maintained at Caltech, at http://www.astro.caltech.edu/~lgg/spider_front.htm.
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    See the full article here.

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    About Princeton: Overview

    Princeton University is a vibrant community of scholarship and learning that stands in the nation’s service and in the service of all nations. Chartered in 1746, Princeton is the fourth-oldest college in the United States. Princeton is an independent, coeducational, nondenominational institution that provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences and engineering.

    As a world-renowned research university, Princeton seeks to achieve the highest levels of distinction in the discovery and transmission of knowledge and understanding. At the same time, Princeton is distinctive among research universities in its commitment to undergraduate teaching.

    Today, more than 1,100 faculty members instruct approximately 5,200 undergraduate students and 2,600 graduate students. The University’s generous financial aid program ensures that talented students from all economic backgrounds can afford a Princeton education.

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  • richardmitnick 12:25 pm on December 5, 2014 Permalink | Reply
    Tags: , , , , CMB, , , ,   

    From physicsworld: “Planck offers another glimpse of the early universe” 

    physicsworld
    physicsworld.com

    Dec 4, 2014
    Tushna Commissariat

    Results of four years of observations made by the Planck space telescope provide the most precise confirmation so far of the Standard Model of cosmology, and also place new constraints on the properties of potential dark-matter candidates. That is the conclusion of astronomers working on the €700m mission of the European Space Agency (ESA). Planck studies the intensity and the polarization of the cosmic microwave background (CMB), which is the thermal remnant of the Big Bang. These latest results will no doubt frustrate cosmologists, because Planck has so far failed to shed much light on some of the biggest mysteries of physics, including what constitutes the dark matter and dark energy that appears to dominate the universe.

    e
    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe)

    ESA Planck
    ESA Planck schematic
    ESA/Planck

    Cosmic Background Radiation Planck
    Cosmic Background Radiation per Planck

    WMAP
    NASA/WMAP spacecraft

    Cosmic Background Radiation per WMAP
    Cosmic Background Radiation per WMAP

    Planck ran from 2009–2013, and the first data were released in March last year, comprising temperature data taken during the first 15 months of observations. A more complete data set from Planck will be published later this month, and is being previewed this week at a conference in Ferrara, Italy (Planck 2014 – The microwave sky in temperature and polarization). So far, Planck scientists have revealed that a previous disagreement of 1–1.5% between Planck and its predecessor – NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) – regarding the mission’s “absolute-temperature” measurements has been reduced to 0.3%.

    Winnowing dark matter

    Planck’s latest measurement of the CMB polarization rules out a class of dark-matter models involving particle annihilation in the early universe. These models were developed to explain excesses of cosmic-ray positrons that have been measured by three independent experiments – the PAMELA mission, the Alpha Magnetic Spectrometer and the Fermi Gamma-Ray Space Telescope.

    INFN PAMELA spacecraft
    PAMELA

    AMS-02
    AMS-02

    NASA Fermi Telescope
    NASA/Fermi

    The Planck collaboration also revealed that it has, for the first time, “detected unambiguously” traces left behind by primordial neutrinos on the CMB. Such neutrinos are thought to have been released one second after the Big Bang, when the universe was still opaque to light but already transparent to these elusive particles. Planck has set an upper limit (0.23 eV/c2) on the sum of the masses of the three types of neutrinos known to exist. Furthermore, the new data exclude the existence of a fourth type of neutrino that is favoured by some models.

    Planck versus BICEP2

    Despite the new data, the collaboration did not give any insights into the recent controversy surrounding the possible detection of primordial “B-mode” polarization of the CMB by astronomers working on the BICEP2 telescope.

    BICEP 2
    BICEP 2 interior
    BICEP 2 with South Pole Telescope

    If verified, the BICEP2 observation would be “smoking-gun” evidence for the rapid “inflation” of the early universe – the extremely rapid expansion that cosmologists believe the universe underwent a mere 10–35 s after the Big Bang. A new analysis of polarized dust emission in our galaxy, carried out by Planck earlier in September, showed that the part of the sky observed by BICEP2 has much more dust than originally anticipated, and while this did not completely rule out BICEP2’s original claim, it established that the dust emission is nearly as big as the entire BICEP2 signal. Both Planck and BICEP2 have since been working together on joint analysis of their data, but a result is still forthcoming.

    [THIS IS THE BEST WE CAN DO UNTIL ESA RELEASES THEIR LATEST FINDINGS FROM PLANCK]

    See the full article here.

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  • richardmitnick 9:44 pm on December 3, 2014 Permalink | Reply
    Tags: , , , , CMB, , , ,   

    From Ethan Siegel: “The Moment of Truth for BICEP2” 

    Starts with a bang
    Starts with a Bang

    Dec 2, 2014
    Ethan Siegel

    “The paradigm of physics — with its interplay of data, theory and prediction — is the most powerful in science.” -Geoffrey West

    Earlier this year, the BICEP2 experiment shook up the world of cosmology, announcing that they had detected gravitational waves originating from before the Big Bang! Not only did they announce this, but they announced that they had done so with a signal in excess of 5σ, which is regarded as the gold standard for a detection in physics.

    BICEP 2
    BICEP 2 interior
    BICEP2 (With South Pole Telescope

    1
    Image credit: BICEP2 Collaboration — P. A. R. Ade et al, 2014 (R).

    But this may all turn out — despite the hoopla — to be absolutely nothing. Or, as it were, nothing more than a phantasm, as the observed signal may have originated from a source as mundane as our own galaxy, and have nothing to do with anything from billions of years ago!

    How did we get into this mess, and how do we get out of it? The answer to both questions is “science,” and it’s a great illustration of how the process and the body of knowledge actually evolves. Put your preconceptions of how it ought to work aside, and let’s dive in!

    2
    Image credit: ESA and the Planck Collaboration.

    This is a snapshot of the cosmic microwave background (CMB), the leftover glow from the Big Bang, as viewed by the Planck satellite. Planck has the best resolution of any all-sky map of the CMB, getting down to resolutions smaller than one tenth of a degree. The temperature fluctuations are minuscule: on the order of just a few tens of microKelvin, less than 0.01% of the actual CMB temperature.

    3
    Image credit: Wikimedia Commons user SuperManu.

    But buried in this signal is another, even more subtle one: the signal of photon polarization.

    4
    Image credit:the BICEP2 collaboration, via http://www.cfa.harvard.edu/news/2014-05.

    Basically, when photons pass through electrically charged particles in certain configurations, their polarizations — or how their electric and magnetic fields are oriented — are affected. If we look at how the two types of polarization, the E-modes and B-modes, are affected on a variety of angular scales, we ought to be able to reconstruct what caused these signals.

    2
    7
    Images credit: Amanda Yoho [Upper]; http://b-pol.org/ [Lower], of an E-mode polarization pattern at left and a B-mode pattern at right.

    A portion of this signal, in addition to charged particles, could also originate from gravitational waves created in the early Universe. There are two main classes of models of inflation that give us a Universe consistent with what we observe in all ways: new inflation, which was actually the second model (and first viable model) ever proposed, and chaotic inflation, which was the third model (and second viable one).

    9
    o
    Images credit: two inflation potentials, with chaotic inflation [Upper] and new inflation [Lower] shown. Chaotic inflation generates very large gravitational waves, while new inflation generates tiny ones. Generated by me, using google graph.

    These two models of inflation make vastly different predictions for gravitational radiation: new inflation predicts gravitational waves (and primordial B-modes) that are extraordinarily tiny, and well beyond the reach of any current or even planned experiment or observatory, while chaotic inflation predicts huge B-modes, some of the largest ones allowable. These signatures have a characteristic frequency spectrum and affect all wavelengths of light identically, so it should be an easy signal to find if our equipment is sensitive to it.

    And that’s where BICEP2 comes in.

    y
    Image credit: Sky and Telescope / Gregg Dinderman, via http://www.skyandtelescope.com/news/First-Direct-Evidence-of-Big-Bang-Inflation-250681381.html.

    Rather than measuring the whole sky, BICEP2 measured just a tiny fraction of the sky — about three fingers held together at arm’s length worth — but were able to tease out both the E-mode and B-mode polarization signals. And based on their analysis of the B-modes, which was very careful and very good, mind you, they claimed the greater-than-5σ detection.

    What this means is that they had enough data so that the odds that what they were seeing was a “fluke” of having observed just a serendipitous patch of sky was tiny, or a one in 1.7 million chance. Flukes happen all the time at the one-in-100 level or the one-in-1,000, but one-in-1.7 million flukes… well, let’s just say you don’t win the lotto jackpot very often.

    But there’s another type of error that they didn’t report. Not a statistical error, which is the kind you can improve on by taking more data, but a systematic error, which could be an effect that causes what you think is your signal, but is actually due to some other source! This type of error normally goes undetected because if you knew about it you’d account for it!

    This is exactly what happened a couple of years ago, if you remember the “faster-than-light-neutrino” business. An experiment at CERN had reported the early arrival by just a few nanoseconds of thousands upon thousands of neutrinos, meaning that they would have exceeded the speed of light by something like 0.003%, a small but meaningful amount. As it turned out, the neutrinos weren’t arriving early; there was a loose cable that accounted for the error!

    f
    Image credit: ESA / Planck Collaboration, via http://www.mpa-garching.mpg.de/mpa/institute/news_archives/news1101_planck/news1101_planck-en-print.html.

    Well, one of the things the BICEP2 team didn’t measure was the galactic foreground emission. Polarized light — including light that contains these B-modes — gets emitted by the Milky Way galaxy, and that can contaminate your signal. The BICEP2 team used a very clever trick to try and eliminate this, by interpolating unreleased Planck data about galactic foregrounds, but when the Planck team actually released their data, the foregrounds were significantly different from what BICEP2 had anticipated. And with the new Planck data, the announcement of a “discovery” needed to be walked back; the evidence was now something like a one-in-200 chance of being a fluke.

    l
    Image credit: John Kovac, viahttp://cosmo2014.uchicago.edu/depot/invited-talk-kovac-john.pdf.

    In other words, although gravitational waves could have caused this signal, so could other, far more mundane sources, including just our boring old galaxy!

    Sometime later this month, the Planck team will release their all-sky polarization results, and either at that moment or shortly thereafter, we’ll find out whether there really are gravitational waves from inflation that can be detected with our current generation of telescopes, satellites and observatories. We’ll find out whether chaotic inflation is right, or whether we need to keep searching for the gravitational wave signal from before the Big Bang. We already have the density fluctuation signal, so we can be confident that inflation happened. It’s just a question of which type.

    n
    Image credit: Bock et al. (2006, astro-ph/0604101); modifications by me.

    Stay curious, stay hungry for more knowledge, but always demand that your scientific claims be independently verified, that your possible systematic errors be checked, and that you have overwhelming evidence before believing the extraordinary claims. It’s easy to make a bold statement; it’s hard to start a bona fide scientific revolution!

    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.

     
  • richardmitnick 7:01 am on December 2, 2014 Permalink | Reply
    Tags: , , , CMB, , , ,   

    From NYT: “New Images Refine View of Infant Universe” 

    New York Times

    The New York Times

    DEC. 1, 2014

    NYT Dennis Overbye
    Dennis Overbye

    In a throwback to another era in cosmic history, astronomers on Monday discussed the birth of the universe in a 15th-century palace, the Palazzo Costabili in Ferrara, Italy, where the amenities do not include Internet access.

    The subject of Planck 2014, as the meeting is called, is a new baby picture — and all of the accompanying vital statistics — of the universe when it was 380,000 years old and space was as hot as the surface of the sun. The portrait taker was the European Space Agency’s Planck satellite, which spent three years surveying a haze of microwave radiation left over from the last moments of the Big Bang with a bevy of sensitive radio receivers.

    Cosmic Background Radiation Planck
    CMB

    ESA Planck
    ESA/Planck

    The data will not be published until Dec. 22 in the journal Astronomy & Astrophysics, and the lack of Internet access frustrated astronomers who had planned on watching a webcast of the proceedings but found themselves relying on Twitter feeds instead.

    At least, they reported, the coffee was suitably strong.

    The new data largely confirms and refines the picture from a temperature map of the microwaves that Planck scientists, a multinational collaboration led by Jan Tauber of the European Space Agency, produced in 2013, showing the faint irregularities from which gargantuan features like galaxies would grow. Its microwave portrait reveals a universe 13.8 billion years old that is precisely mysterious, composed of 4.9 percent atomic matter, 26.6 percent mysterious dark matter that is not atomic, and 68.5 percent of even more mysterious dark energy, the glib name for whatever it is that seems to be blowing the universe apart.

    new
    A map of a patch of sky showing the temperature and polarization of cosmic microwaves from the end of the Big Bang, as reflected by dust swirling in the magnetic field of the Milky Way. Credit European Space Agency

    The result is a resounding victory for a sort of Standard Model of Cosmology that has grown up over the last two decades, said Lyman Page, a Princeton astrophysicist, in a phone call from Ferrara. “What we see is pretty impressive,” he said. “It’s amazing that just six parameters describe the universe.”

    Standard Model of Cosmology Inflation Lambda Model
    Lambda-CDM model

    Standard Model of Cosmology
    Another view

    Cosmologists still do not know what dark matter — the material that provides the gravitational scaffolding for galaxies — is, but the Planck results have increased their knowledge of what it is not, according to the French Center for National Scientific Research.

    Recently space experiments like NASA’s Fermi Gamma-ray Space Telescope and Alpha Magnetic Spectrometer have recorded excess cosmic ray emissions that, some say, could be evidence of a certain kind of dark matter particles colliding and annihilating one another.

    NASA Fermi Telescope
    NASA/Fermi

    NASA AMS02 device
    NASA/AMS-02

    After Planck, we need another answer for those experiments, the French agency concluded in a statement.

    Neal Weiner, a particle theorist at New York University, who is not part of Planck, concurred. That model of dark matter, he said in an email, if not completely excluded, now could be severely constrained. “If this holds up, at the very least a possibility to discover dark matter is now diminished.”

    Planck dealt a blow to another possible dark matter candidate, namely a brand of the ghostly particles known as neutrinos. Physicists have known of three types of neutrinos for some time and have wondered if there were any more, whose accumulated mass would affect the evolution of the universe. Planck’s results leave little room for a fourth kind, so-called sterile neutrinos.

    Compounding the frustration of cosmologists in the room in Ferrara and at large was an issue that has galvanized them for the better part of a year: whether astronomers had detected the very beginnings of the Big Bang in the form of space-time ripples known as gravitational waves.

    Gravitational Wave Background
    Gravitational Waves per BICEP2 radio telescope.

    BICEP 2
    BICEP 2 interior
    BICEP 2 with South Pole Telescope

    The added value of the new Planck data is a map showing how the microwaves are polarized, information that could shed light on what was going on when the universe was a trillionth of a trillionth of a trillionth of a second old, and in the grip of forces about which physicists can only speculate.

    Among the hottest topics of speculation these days is the idea — known as inflation — that the universe underwent a violent and brief surge of expansion in the earliest moments, settling the geometry and other aspects of the present universe. Such an explosion, theorists say, would have left faint corkscrew swirls, known technically as B-modes, in the pattern of polarization of the microwaves.

    In March there was much excitement when a team of American astronomers operating a radio telescope at the South Pole called Bicep2 announced they had detected such a pattern. Alan Guth of M.I.T., one of the inventors(?) [theorist would be better] of inflation, was at the news conference at Harvard announcing the results.

    Alan Guth
    Alan Guth

    After three months of spirited debate, the astronomers conceded, however, that their signal could have been caused by interstellar dust, which can also twist the microwaves.

    Enter Planck, which observed the microwaves in nine different frequencies, making it easy to distinguish dust. Bicep2 had only one frequency.

    A preliminary report from Planck in September confirmed that there was enough dust in Bicep2’s patch of sky to account for the twisting, but there are still large uncertainties that leave room for primordial gravitational waves.

    Subsequently, Planck and Bicep agreed to pool their data for a joint analysis.

    Planck scientists have meanwhile published their own polarization maps, which astronomers say will be useful for studying how the anti-gravitational push of dark energy and the gravitational pull of dark matter orchestrated the growth of galaxies and the universe when it was two or three billion years old — a sensitive age.

    The bumps in the microwave maps that eventually grow to galaxies amount to a temperature difference of only about 75-millionths of a Kelvin, in an otherwise uniform hiss. To measure polarization, radio astronomers have to discern temperature differences about a tenth of that.

    The difficulty of doing this research, while the world looks on, can be gauged by the number of missed deadlines. Planck researchers originally hoped to have their polarization studies done this summer. Recently they had set November as their deadline, aiming to present the results at this conference in Ferrara. Likewise, the joint Bicep/Planck paper is now expected this month or in January.

    Asked about this, David Spergel, a Princeton cosmologist and veteran of cosmic microwave studies who had spent the day fielding Twitter messages from Ferrara, said he had adopted an acronym often used by NASA in announcing launch dates: NET, meaning “No Earlier Than.”

    See the full article here.

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  • richardmitnick 2:31 pm on November 17, 2014 Permalink | Reply
    Tags: , , , CMB, ,   

    From SPACE.com: “Big Bang’s Echo May Reveal Skeleton of the Universe” 

    space-dot-com logo

    SPACE.com

    November 17, 2014
    Calla Cofield

    Scientists may soon get a look at the universe’s skeleton by taking a close look at light left over from the Big Bang, which can be used to reveal the presence of matter like stars, galaxies, black holes and even larger structures in the otherwise empty universe. It’s a lot like an X-ray revealing bones in a body, but on a cosmic scale.

    pb

    X-ray machines work by shining light over an entire area and detecting how different materials react. The light passes through tissue, but is stopped by bone.

    In a similar way, scientists with the international POLARBEAR collaboration want to use a diffuse light that fills every corner of the cosmos to indicate where there is matter and where there is none. POLARBEAR studies the cosmic microwave background (CMB) — the surviving light from the infant universe that is normally seen a kind of baby picture of the cosmos. Scientists estimate the universe is about 13.8 billion years old.

    Cosmic Background Radiation Planck
    CMB per ESA/Planck

    ESA Planck
    ESA Planck schematic
    ESA/Planck

    “We’re using the light that we’ve usually used to measure the seeds of the structure of the universe, to measure the whole tree,” said Adrian Lee, a professor of physics at the University of California Berkeley, and a lead scientist with POLARBEAR. “But the mechanism [we use] is pretty different. Instead of looking at a baby picture, we’re looking at the distortion of the baby picture.”
    Bending cosmic light

    Just as the bones in a skeleton are not randomly scattered in the body, the mass in the universe is not randomly scattered through space. Forces such as gravity drive the organization of matter, so stars get grouped into galaxies; galaxies herd together into galaxy clusters; and on an even larger scale, scientists think matter in the universe is arranged into a structure resembling a web, with vast regions of emptiness between strings of galaxy groups.

    The gravity of massive objects can bend light. The light moves around the object like water going around a rock in a stream. This bending causes a change in the CMB, and POLARBEAR scientists say they have now detected that change.

    The bending of light by a massive object is called gravitational lensing, and it changes a property of the light called polarization. When sunlight reflects off the surface of water, it often becomes polarized. Polarizing sunglasses can block this polarized light, but they do not block the sunlight coming from above — ideal for water sport fans.

    CMB light that has not been gravitationally lensed — that has never bumped into any type of matter — has a so-called E-mode polarization. New results from the collaboration show that the researchers can detect something called B-mode polarization, which means the CMB has encountered a massive object on the way to Earth.

    POLARBEAR has only just demonstrated that it can detect this polarization, but eventually, it could create a sketch of the large-scale skeleton inside the universal body.

    Huan Tran Telescope
    The Huan Tran Telescope, located in Chile’s Atacama Desert, looks for light left over from the big bang. Scientists with the POLARBEAR collaboration want to use that light to map the location of matter in the universe.
    Credit: POLARBEAR collaboration

    Dark energy and exotic dragons

    Seeing the universe’s skeleton — the location and structure of all matter — could tell scientists if they’ve got the right idea about how matter in the universe is arranged, and if there are yet-unknown forces acting on it in peculiar ways.

    “There’s some possibility [the structure] won’t look the way theorists predict,” Lee said. “[POLARBEAR] could confirm that the universe is acting the way we think it is; that there are no exotic dragons out there changing the signal.”

    The most dominant force in our universe is dark energy, but scientists know very little about it — only that it’s causing our universe to expand like a balloon. They don’t know when dark energy started this expansion, but Lee said it would have had an effect on how structures formed.

    “Gravity wants to pull structures together but dark energy wants to pull them apart,” Lee said. “If dark energy was acting more strongly early on in the universe that would suppress structure formation, because [the dark energy] would be yanking masses away from each other.” Lee said future data from POLARBEAR could help identify when dark energy started pushing the universe apart.
    Flexing BICEP2

    Earlier this year, members of the BICEP2 collaboration announced that they had detected B-mode polarization in the CMB. But that polarization signal comes from a different source than the one detected by POLARBEAR. The BICEP2 polarization may come from gravitational waves, or ripples in space-time, in the early universe.

    BICEP 2
    BICEP 2 interior
    BICEP 2 (Upper picture also shows the South Pole Telescope)

    Gravitational Wave Background
    Gravitational Waves projected by BICEP2

    Detection of this type of B-mode polarization would indirectly demonstrate the existence of gravitational waves, and their presence in our early universe. But following BICEP2’s announcement, observations by the Planck satellite have raised questions about whether the results were contaminated by space dust.

    It’s possible, said Lee, that POLARBEAR could eventually measure polarization created by gravitational waves from the inflating universe. Those polarization patterns are larger on the sky than the lensing polarization that POLARBEAR has measured, but as BICEP2 has shown, they are in some ways more challenging to observe.

    POLARBEAR’s observations alone can provide only a two-dimensional map of the matter in the universe. But with the help of other telescopes, Lee said it would be possible to create a three-dimensional map, and to even determine when the structure appeared in the universe.

    “If we use other data, if we cross correlate, we could look at the structure of matter over the whole history of the universe,” Lee said. “That’s the strength of all the data sets together.”

    See the full article here.

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  • richardmitnick 9:20 am on October 24, 2014 Permalink | Reply
    Tags: , , , CMB, , , POLARBEAR Collaboration   

    From phys.org: “POLARBEAR detects curls in the universe’s oldest light” 

    physdotorg
    phys.org

    Oct 21, 2014
    Susan Brown

    Cosmologists have made the most sensitive and precise measurements yet of the polarization of the cosmic microwave background.

    image

    The report, published October 20 in the Astrophysical Journal, marks an early success for POLARBEAR, a collaboration of more than 70 scientists using a telescope high in Chile’s Atacama desert designed to capture the universe’s oldest light.

    “It’s a really important milestone,” said Kam Arnold, the corresponding author of the report who has been working on the instrument for a decade. “We’re in a new regime of more powerful, precision cosmology.” Arnold is a research scientist at UC San Diego’s Center for Astrophysics and Space Sciences and part of the cosmology group led by physics professor Brian Keating.

    POLARBEAR measures remnant radiation from the Big Bang, which has cooled and stretched with the expansion of the universe to microwave lengths. This cosmic microwave background, the CMB, acts as an enormous backlight, illuminating the large-scale structure of the universe and carrying an imprint of cosmic history.

    Cosmic Background Radiation Planck
    CMB from Planck

    Arnold and many others have developed sensitive instruments called bolometers to measure this light. Arrayed in the telescope, the bolometers record the direction of the light’s electrical field from multiple points in the sky.

    “It’s a map of all these little directions that the light’s electric field is pointing,” Arnold explained.

    POLARBEAR has now mapped these angles with resolution on a scale of about 3 arcminutes, just one-tenth the diameter of the full moon..

    The team found telling twists called B-Modes in the patterns of polarization, signs that this cosmic backlight has been warped by intervening structures in the universe, including such mysteries as dark matter, composed of substance that remains unknown, and the famously aloof particles called neutrinos, which elude capture making them difficult to study.

    This initial report, the result of the first season of observation, maps B-modes in three small patches of sky.

    Dust in our own galaxy also emits polarized radiation like the CMB and has influenced other measurements. But these patches are relatively clean, Arnold says. And variations in the CMB polarization due to dust occur on so broad a scale that they do not significantly influence the finer resolution B-modes in this report.

    “We are confident that these B-modes are cosmological rather than galactic in origin,” Arnold said.

    Observations continue, and the data stream will ultimately be fed by additional telescopes comprising the Simons Array. Together they will map wider swaths of the sky, making fundamental discoveries possible.

    Simmons Array

    “POLARBEAR is a real tour de force. With a relatively small, but strong, UC-led team we have surpassed the next-nearest competitors by an order of magnitude in sensitivity. We have paved the way towards solving the deepest mysteries in the quest to understand matter and energy at the beginning of time,” said Brian Keating.

    POLARBEAR is a collaboration of scientists from many institutions including experiment founder, Adrian Lee, professor of physics at UC Berkeley.

    See the full article here.

    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

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