Showing posts with label BICEP2. Show all posts
Showing posts with label BICEP2. Show all posts

Saturday, February 20, 2016

Sunyaev–Zel'dovich effect

The Sunyaev–Zel'dovich effect (often abbreviated as the SZ effect) is the result of high energy electrons distorting the cosmic microwave background radiation (CMB) through inverse Compton scattering, in which the low energy CMB photons receive an average energy boost during collision with the high energy cluster electrons. Observed distortions of the cosmic microwave background spectrum are used to detect the density perturbations of the universe. Using the Sunyaev–Zel'dovich effect, dense clusters of galaxies have been observed.

Contents

Introduction


The Sunyaev–Zel'dovich effect can be divided into:
  • thermal effects, where the CMB photons interact with electrons that have high energies due to their temperature
  • kinematic effects, a second-order effect where the CMB photons interact with electrons that have high energies due to their bulk motion (also called the Ostriker–Vishniac effect, after Jeremiah P. Ostriker and Ethan Vishniac.[1])
  • polarization
Rashid Sunyaev and Yakov Zel'dovich predicted the effect, and conducted research in 1969, 1972, and 1980. The Sunyaev–Zel'dovich effect is of major astrophysical and cosmological interest. It can help determine the value of the Hubble constant. To distinguish the SZ effect due to galaxy clusters from ordinary density perturbations, both the spectral dependence and the spatial dependence of fluctuations in the cosmic microwave background are used. Analysis of CMB data at higher angular resolution (high l values) requires taking into account the Sunyaev–Zel'dovich effect.

First detected by Mark Birkinshaw at the University of Bristol

Current research is focused on modelling how the effect is generated by the intracluster plasma in galaxy clusters, and on using the effect to estimate the Hubble constant and to separate different components in the angular average statistics of fluctuations in the background. Hydrodynamic structure formation simulations are being studied to gain data on thermal and kinetic effects in the theory.[2] Observations are difficult due to the small amplitude of the effect and to confusion with experimental error and other sources of CMB temperature fluctuations. However, since the Sunyaev–Zel'dovich effect is a scattering effect, its magnitude is independent of redshift. This is very important: it means that clusters at high redshift can be detected just as easily as those at low redshift. Another factor which facilitates high-redshift cluster detection is the angular scale versus redshift relation: it changes little between redshifts of 0.3 and 2, meaning that clusters between these redshifts have similar sizes on the sky. The use of surveys of clusters detected by their Sunyaev–Zel'dovich effect for the determination of cosmological parameters has been demonstrated by Barbosa et al. (1996). This might help in understanding the dynamics of dark energy in forthcoming surveys (SPT, ACT, Planck).

 

Timeline of observations

 

See also

 

References


  • Ostriker, Jeremiah P. & Vishniac, Ethan T. (1986). "Effect of gravitational lenses on the microwave background, and 1146+111B,C". Nature 322 (6082): 804. Bibcode:1986Natur.322..804O. doi:10.1038/322804a0.
  • Cunnama D., Faltenbacher F.; Passmoor S., Cress C.; Cress, C.; Passmoor, S. (2009). "The velocity-shape alignment of clusters and the kinetic Sunyaev-Zeldovich effect". MNRAS Letters 397 (1): L41–L45. arXiv:0904.4765. Bibcode:2009MNRAS.397L..41C. doi:10.1111/j.1745-3933.2009.00680.x.
  • Hand, Nick; Addison, Graeme E.; Aubourg, Eric; Battaglia, Nick; Battistelli, Elia S.; Bizyaev, Dmitry; Bond, J. Richard; Brewington, Howard; Brinkmann, Jon; Brown, Benjamin R.; Das, Sudeep; Dawson, Kyle S.; Devlin, Mark J.; Dunkley, Joanna; Dunner, Rolando; Eisenstein, Daniel J.; Fowler, Joseph W.; Gralla, Megan B.; Hajian, Amir; Halpern, Mark; Hilton, Matt; Hincks, Adam D.; Hlozek, Renée; Hughes, John P.; Infante, Leopoldo; Irwin, Kent D.; Kosowsky, Arthur; Lin, Yen-Ting; Malanushenko, Elena; et al. (2012). "Detection of Galaxy Cluster Motions with the Kinematic Sunyaev-Zel'dovich Effect". Physical Review Letters 109 (4): 041101. arXiv:1203.4219. Bibcode:2012PhRvL.109d1101H. doi:10.1103/PhysRevLett.109.041101. PMID 23006072.
  • Mroczkowski, Tony; Dicker, Simon; Sayers, Jack; Reese, Erik D.; Mason, Brian; Czakon, Nicole; Romero, Charles; Young, Alexander; Devlin, Mark; Golwala, Sunil; Korngut, Phillip; Sarazin, Craig; Bock, James; Koch, Patrick M.; Lin, Kai-Yang; Molnar, Sandor M.; Pierpaoli, Elena; Umetsu, Keiichi; Zemcov, Michael (2012). "A Multi-wavelength Study of the Sunyaev-Zel'dovich Effect in the Triple-merger Cluster MACS J0717.5+3745 with MUSTANG and Bolocam". Astrophysical Journal 761: 47. arXiv:1205.0052. Bibcode:2012ApJ...761...47M. doi:10.1088/0004-637X/761/1/47 (inactive 2015-01-09).

  • Sayers, Jack; Mroczkowski, T.; Zemcov, M.; Korngut, P. M.; Bock, J.; Bulbul, E.; Czakon, N. G.; Egami, E.; Golwala, S. R.; Koch, P. M.; Lin, K.-Y.; Mantz, A.; Molnar, S. M.; Moustakas, L.; Pierpaoli, E.; Rawle, T. D.; Reese, E. D.; Rex, M.; Shitanishi, J. A.; Siegel, S.; Umetsu, K. (2013). "A Measurement of the Kinetic Sunyaev-Zel'dovich Signal Toward MACS J0717.5+3745". Astrophysical Journal 778: 52. arXiv:1312.3680. Bibcode:2013ApJ...778...52S. doi:10.1088/0004-637X/778/1/52.

  • Further reading

    External links

    Wednesday, July 02, 2014

    Proofing BICEP2

    Inflation—the hypothesis that the Universe underwent a phase of superluminal expansion in a brief period following the big bang—has the potential of explaining, from first principles, why the Universe has the structure we see today. It could also solve outstanding puzzles of standard big-bang cosmology, such as why the Universe is, to a very good approximation, flat and isotropic (i.e., it looks the same in all directions). Yet we do not yet have a compelling model, based on fundamental particle physics principles, that explains inflation. And despite its explanatory power and a great deal of suggestive evidence, we still lack an unambiguous and direct probe of inflation. Theorists have developed different models for inflation, which all share a common, robust prediction: Inflation would have created a background of gravitational waves that could have an observable effect. These waves would cause subtle, characteristic distortions of the cosmic microwave background (CMB)—the oldest light in the Universe, released when photons decoupled from matter and the Universe became transparent to radiation. Viewpoint: Peering Back to the Beginning of Time

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    First Direct Evidence of Cosmic Inflation


    Almost 14 billion years ago, the universe we inhabit burst into existence in an extraordinary event that initiated the Big Bang. In the first fleeting fraction of a second, the universe expanded exponentially, stretching far beyond the view of our best telescopes. All this, of course, was just theory.

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     LSC Congratulates BICEP2 Colleagues

     

    18 March 2014 - The BICEP2 Collaboration result, if confirmed, is a landmark discovery in cosmology, allowing us for the first time to peer back almost to the moment of the Big Bang through the observation of the imprint of primordial gravitational waves on the cosmic microwave background. The LIGO Scientific Collaboration congratulates our BICEP colleagues on their accomplishment and will further follow discoveries and implications of these observations with great interest. - See more at: http://www.ligo.org/news/bicep-result.php#sthash.mJlemItG.dpuf
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    Tuesday, April 15, 2014

    Multiverse or Universe? - Andre Linde (SETI Talks)



    Published on Jan 1, 2013
    SETI Talks archive: http://seti.org/talks
    Cosmological observations show that the universe is very uniform on the maximally large scale accessible to our telescopes, and the same laws of physics operate in all of its parts that we can see now. The best theoretical explanation of the uniformity of our world was provided by inflationary theory, which was proposed 30 years ago.
    See:  Multiverse or Universe? - Andre Linde (SETI Talks)

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    Thursday, April 10, 2014

    The Map of B Mode Imprints


    Figure 3: Left: BICEP2 apodized E-mode and B-mode maps filtered to 50 < ℓ < 120. Right: The equivalent maps for the first of the lensed-ΛCDM+noise simulations. The color scale displays the E-mode scalar and B-mode pseudoscalar patterns while the lines display the equivalent magnitude and orientation of the linear polarization. Note that excess B-mode is detected over lensing+noise with high signal-to-noise ratio in the map (s/n > 2 per map mode at ℓ ≈ 70). (Also note that the E-mode and B-mode maps use different color/length scales.)

    BICEP2 2014 Release Figures from Papers

     You know the distinctions on how one might see information as purported to exist as gravitational waves  of course held my perspective. Like others,  is this a way in which BICEP has illustrated something of the every nature of space-time, as to my thoughts then, when it really was only about seeing a footprint in the WMAP.


    Gravitational waves open up a new window on the universe that will allow us to probe events for which no electromagnetic signature exists. In the next few years, the ground-based interferometers GEO-600, LIGO, VIRGO and TAMA should be able to detect the high-frequency gravitational waves produced by extreme astrophysical objects, providing the first direct detection of these disturbances in space–time. With its much longer arm lengths, the space-based interferometer LISA will, if launched, be able to detect lower-frequency gravitational waves, possibly those generated by phase transitions in the early universe. At even lower frequencies, other experiments will look for tiny signatures of gravitational waves in the cosmic microwave background. Source: NASA.

    Gravity Wave Spectrum


    So it is a footprint then and I might show some of those maps and ask what do these footprints show in the early universe as to say, that given the inflationary timeline what can be garnered about looking back so far as to suggest 13.8 billion years and have such an imprint hold relevance, and equal the very nature of space-time itself.

    Figure 18: Results of far-field beam characterization with a chopped thermal source. Left: Typical measured far-field beam on a linear scale. Middle: The Gaussian fit to the measured beam pattern. Right: The fractional residual after subtracting the Gaussian fit. Note finer color scale in the right-hand differenced map.

    BICEP2 2014 Release Figures from Papers



    The nature of the question for me is a "sensor mode developmental model" that chooses to exemplify gravitational waves over another and I had to make this clear for myself. So you can see where this has lead me. To where I want to further understand. If you choose not to show a comment then I guess that is where I lose.

     
    Weber developed an experiment using a large suspended bar of aluminum, with a high resonant Q at a frequency of about 1 kH; the oscillation of the bar after it had been excited could be measured by a series of piezoelectric crystals mounted on it. The output of the system was put on a chart recorder like those used to record earthquakes. Weber studied the excursions of the pen to look for the occasional tone of a gravitational wave passing through the bar...

    See:Weber Bars Ring True?

    The analogy rests with how the nature of gravitational waves had been sounded so as to show a connection to the WMAP as a footprint. So you have this 2 dimensional map surface as to exemplary how gravitational waves may appear on it, yet,  the visual extent of that correlation is representative to me of a defined configuration space. You need your physics in order to establish any correlation to the timeline of the inflationary model and to see that such a map reveals efforts to penetrate the Planck era. To suggest quantum gravity.

    At least two detectors located at widely separated sites are essential for the unequivocal detection of gravitational waves. Local phenomena such as micro-earthquakes, acoustic noise, and laser fluctuations can cause a disturbance at one site, simulating a gravitational wave event, but such disturbances are unlikely to happen simultaneously at widely separated sites. 

    Correlating Gravitational Wave Production in LIGO
    See Also:


    So indeed to have such a map is very telling to me not just of the imprint but also of the sensory mode we had chosen to illustrate that map of the B mode representation as a valid model description of that early universe.

    Monday, March 31, 2014

    Sunday, March 23, 2014

    Are Artifacts of CMB Right Next to Me?

     Looking back seems strange to me and that if one is to take such a position then evidence must exist in this very moment?

    Models of Earlier Events

    This may seem like a stupid question to some, but for me it is really about looking at where I exist in the universe and what exists right next to us in the same space. I am not sure if that makes any sense but hopefully somebody out there can help me focus better.

    ESA and the Planck Collaboration
    The mission's main goal is to study the cosmic microwave background – the relic radiation left over from the Big Bang – across the whole sky at greater sensitivity and resolution than ever before.
    The cosmic microwave background (CMB) is the furthest back in time we can explore using light.
    The cosmic microwave background (CMB) is detected in all directions of the sky and appears to microwave telescopes as an almost uniform background. Planck’s predecessors (NASA's COBE and WMAP missions) measured the temperature of the CMB to be 2.726 Kelvin (approximately -270 degrees Celsius) almost everywhere on the sky. 
    So with parsing some of these points from the link associated above with picture, I am not sure if my question has been properly asked.

     A discussion about the definition of nothing.

    For me then too, I would always wonder about "what nothing is" as that to relates to the question about what can exist right next to me. It was meant to be logical and not metaphysical question, so as to be reduced to those first moments.

    ***

    If BICEP2′s recent result is correct:

    ” -as big as a large fraction of a percent of the Planck temperature (where the universe would have been hot enough to make black holes just from its own heat) or

    – as small as the temperature corresponding to about the energy of the Large Hadron Collider (where it would barely have been hot enough to make Higgs particles)”


    History of the Universe
    “not of the whole universe but rather just the part of the universe (called, on this website, “the observable patch of the universe“) that we can observe today,”

    Why is this “observable patch” important and where in the CMB map is this located? As strange a question as this might be, can this “observable patch” be right next to us?

    So I am constructing a method here to help us see the universe as if I am on a location within this CMB map.

    "The cosmic microwave background (CMB) is detected in all directions of the sky and appears to microwave telescopes as an almost uniform background. " -See: ESA and Planck Collaboration

    So of course you look at the map,  and for me,  I wonder where we are located on that map. So with regard to that particular patch what does the background look like?-




    "The contents point to a Euclidean flat geometry, with curvature (\Omega_{k}) of −0.0027+0.0039 −0.0038. The WMAP measurements also support the cosmic inflation paradigm in several ways, including the flatness measurement."- WMAP

    So such a illustration and my question about our location and where we are in that "all sky map(CoBE, WMAP, and PLanck)" tells us something about the region we are in? Right next to us,  in this map while seeking our placement, I am curious as to what this region looks like in relation to say another point on that map.


    Cosmological parameters from 2013 Planck results[23][24][25]
    Parameter Age of the universe (Gy) Hubble's constant
    ( kmMpc·s )
    Physical baryon density Physical cold dark matter density Dark energy density Density fluctuations at 8h−1 Mpc Scalar spectral index Reionization optical depth
    Symbol t_0 H_0 \Omega_b h^2 \Omega_c h^2 \Omega_\Lambda \sigma_8 n_s \tau
    Planck
    Best fit
    13.819 67.11 0.022068 0.12029 0.6825 0.8344 0.9624 0.0925
    Planck
    68% limits
    13.813±0.058 67.4±1.4 0.02207±0.00033 0.1196±0.0031 0.686±0.020 0.834±0.027 0.9616±0.0094 0.097±0.038
    Planck+lensing
    Best fit
    13.784 68.14 0.022242 0.11805 0.6964 0.8285 0.9675 0.0949
    Planck+lensing
    68% limits
    13.796±0.058 67.9±1.5 0.02217±0.00033 0.1186±0.0031 0.693±0.019 0.823±0.018 0.9635±0.0094 0.089±0.032
    Planck+WP
    Best fit
    13.8242 67.04 0.022032 0.12038 0.6817 0.8347 0.9619 0.0925
    Planck+WP
    68% limits
    13.817±0.048 67.3±1.2 0.02205±0.00028 0.1199±0.0027 0.685+0.018
    −0.016
    0.829±0.012 0.9603±0.0073 0.089+0.012
    −0.014
    Planck+WP
    +HighL
    Best fit
    13.8170 67.15 0.022069 0.12025 0.6830 0.8322 0.9582 0.0927
    Planck+WP
    +HighL
    68% limits
    13.813±0.047 67.3±1.2 0.02207±0.00027 0.1198±0.0026 0.685+0.017
    −0.016
    0.828±0.012 0.9585±0.0070 0.091+0.013
    −0.014
    Planck+lensing
    +WP+highL
    Best fit
    13.7914 67.94 0.022199 0.11847 0.6939 0.8271 0.9624 0.0943
    Planck+lensing
    +WP+highL
    68% limits
    13.794±0.044 67.9±1.0 0.02218±0.00026 0.1186±0.0022 0.693±0.013 0.8233±0.0097 0.9614±0.0063 0.090+0.013
    −0.014
    Planck+WP
    +highL+BAO
    Best fit
    13.7965 67.77 0.022161 0.11889 0.6914 0.8288 0.9611 0.0952
    Planck+WP
    +highL+BAO
    68% limits
    13.798±0.037 67.80±0.77 0.02214±0.00024 0.1187±0.0017 0.692±0.010 0.826±0.012 0.9608±0.0054 0.092±0.013


    So as we look at this map much is told to us about the Cosmological Parameters and what can be defined in this location we occupy.



    Parameter Value Description
    Ωtot 1.0023^{+0.0056}_{-0.0054} Total density
    w -0.980\pm0.053 Equation of state of dark energy
    r <0.24, k0 = 0.002Mpc−1 (2σ) Tensor-to-scalar ratio
    d ns / d ln k -0.022\pm0.020, k0 = 0.002Mpc−1 Running of the spectral index
    Ωvh2 < 0.0062 Physical neutrino density
    Σmν <0.58 eV (2σ) Sum of three neutrino masses


    See:
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    Monday, March 17, 2014

    BICEP2 Observatory in Antarctica

    Cosmic searches at the South Pole. The BICEP-2 Telescope is the up-facing dish at right. The larger white dish is the South Pole Telescope (SPT), and the building is the Dark Sector Laboratory. Both experiments observe in the millimeter-submillimeter part of the spectrum, mapping polarization patterns in the cosmic background radiation.

    ...... will announce a “major discovery” about B-modes in the cosmic microwave background See: Who should get the Nobel Prize for cosmic inflation?

    UPDATE
    Closing thoughts -
    BICEP2: Primordial Gravitational Waves!
    The BICEP result, if correct, is a spectacular and historic discovery.  In terms of impact on fundamental physics, particularly as a tool for testing ideas about quantum gravity, the detection of primordial gravitational waves is completely unprecedented.  Inflation evidently occurred just two orders of magnitude below the Planck scale, and we have now seen the quantum fluctuations of the graviton.  For those who want to understand how the universe began, and also for those who want to understand quantum gravity, it just doesn't get any better than this.
    In fact, it all seems far too good to be true.  And perhaps it is: check back after another experimental team is able to check the BICEP findings, and then we can really break out the champagne.


    This should be really interesting.

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    Stanford Professor Andrei Linde celebrates physics breakthrough  

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