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Sample records for cosmic background imager

  1. Polarization observations with the Cosmic Background Imager.

    PubMed

    Readhead, A C S; Myers, S T; Pearson, T J; Sievers, J L; Mason, B S; Contaldi, C R; Bond, J R; Bustos, R; Altamirano, P; Achermann, C; Bronfman, L; Carlstrom, J E; Cartwright, J K; Casassus, S; Dickinson, C; Holzapfel, W L; Kovac, J M; Leitch, E M; May, J; Padin, S; Pogosyan, D; Pospieszalski, M; Pryke, C; Reeves, R; Shepherd, M C; Torres, S

    2004-10-29

    Polarization observations of the cosmic microwave background with the Cosmic Background Imager from September 2002 to May 2004 provide a significant detection of the E-mode polarization and reveal an angular power spectrum of polarized emission showing peaks and valleys that are shifted in phase by half a cycle relative to those of the total intensity spectrum. This key agreement between the phase of the observed polarization spectrum and that predicted on the basis of the total intensity spectrum provides support for the standard model of cosmology, in which dark matter and dark energy are the dominant constituents, the geometry is close to flat, and primordial density fluctuations are predominantly adiabatic with a matter power spectrum commensurate with inflationary cosmological models. PMID:15472038

  2. Imaging the cosmic microwave background: The BEAST experiment

    NASA Astrophysics Data System (ADS)

    Natoli, P.; Bersanelli, M.; Childers, J.; Figueiredo, N.; Halevi, D.; Kangas, M.; Levy, A.; Lubin, P.; Mandolesi, N.; Meinhold, P.; Parendo, S.; Staren, J.; Villela, T.; Wuensche, C.

    2001-02-01

    We describe the Santa Barbara BEAST experiment, a balloon borne telescope to image the Cosmic Microwave Background (CMB) radiation anisotropy pattern. Some aspects of the map making pipeline are also discussed. .

  3. The Anisotropy of the Microwave Background to l=3500: Mosaic Observations with the Cosmic Background Imager

    NASA Technical Reports Server (NTRS)

    Pearson, T. J.; Mason, B. S.; Readhead, A. C. S.; Shepherd, M. C.; Sievers, J. L.; Udomprasert, P. S.; Cartwright, J. K.; Farmer, A. J.; Padin, S.; Myers, S. T.; Six, N. Frank (Technical Monitor)

    2002-01-01

    Using the Cosmic Background Imager, a 13-element interferometer array operating in the 26-36 GHz frequency band, we have observed 40 deg (sup 2) of sky in three pairs of fields, each approximately 145 feet x 165 feet, using overlapping pointings: (mosaicing). We present images and power spectra of the cosmic microwave background radiation in these mosaic fields. We remove ground radiation and other low-level contaminating signals by differencing matched observations of the fields in each pair. The primary foreground contamination is due to point sources (radio galaxies and quasars). We have subtracted the strongest sources from the data using higher-resolution measurements, and we have projected out the response to other sources of known position in the power-spectrum analysis. The images show features on scales approximately 6 feet-15 feet, corresponding to masses approximately 5-80 x 10(exp 14) solar mass at the surface of last scattering, which are likely to be the seeds of clusters of galaxies. The power spectrum estimates have a resolution delta l approximately 200 and are consistent with earlier results in the multipole range l approximately less than 1000. The power spectrum is detected with high signal-to-noise ratio in the range 300 approximately less than l approximately less than 1700. For 1700 approximately less than l approximately less than 3000 the observations are consistent with the results from more sensitive CBI deep-field observations. The results agree with the extrapolation of cosmological models fitted to observations at lower l, and show the predicted drop at high l (the "damping tail").

  4. The Cosmic Background Explorer.

    ERIC Educational Resources Information Center

    Gulkis, Samuel; And Others

    1990-01-01

    Outlines the Cosmic Background Explorer (COBE) mission to measure celestial radiation. Describes the instruments used and experiments involving differential microwave radiometers, and a far infrared absolute spectrophotometer. (YP)

  5. The cosmic neutrino background

    NASA Technical Reports Server (NTRS)

    Dar, Arnon

    1991-01-01

    The cosmic neutrino background is expected to consist of relic neutrinos from the big bang, of neutrinos produced during nuclear burning in stars, of neutrinos released by gravitational stellar collapse, and of neutrinos produced by cosmic ray interactions with matter and radiation in the interstellar and intergalactic medium. Formation of baryonic dark matter in the early universe, matter-antimatter annihilation in a baryonic symmetric universe, and dark matter annihilation could have also contributed significantly to the cosmic neutrino background. The purpose of this paper is to review the properties of these cosmic neutrino backgrounds, the indirect evidence for their existence, and the prospects for their detection.

  6. The Anisotropy of the Microwave Background to l = 3500: Deep Field Observations with the Cosmic Background Imager

    NASA Technical Reports Server (NTRS)

    Mason, B. S.; Pearson, T. J.; Readhead, A. C. S.; Shepherd, M. C.; Sievers, J.; Udomprasert, P. S.; Cartwright, J. K.; Farmer, A. J.; Padin, S.; Myers, S. T.; Six, N. Frank (Technical Monitor)

    2002-01-01

    We report measurements of anisotropy in the cosmic microwave background radiation over the multipole range l approximately 200 (right arrow) 3500 with the Cosmic Background Imager based on deep observations of three fields. These results confirm the drop in power with increasing l first reported in earlier measurements with this instrument, and extend the observations of this decline in power out to l approximately 2000. The decline in power is consistent with the predicted damping of primary anisotropies. At larger multipoles, l = 2000-3500, the power is 3.1 sigma greater than standard models for intrinsic microwave background anisotropy in this multipole range, and 3.5 sigma greater than zero. This excess power is not consistent with expected levels of residual radio source contamination but, for sigma 8 is approximately greater than 1, is consistent with predicted levels due to a secondary Sunyaev-Zeldovich anisotropy. Further observations are necessary to confirm the level of this excess and, if confirmed, determine its origin.

  7. The Cosmic Background Explorer

    NASA Technical Reports Server (NTRS)

    Gulkis, Samuel; Lubin, Philip M.; Meyer, Stephan S.; Silverberg, Robert F.

    1990-01-01

    The Cosmic Background Explorer (CBE), NASA's cosmological satellite which will observe a radiative relic of the big bang, is discussed. The major questions connected to the big bang theory which may be clarified using the CBE are reviewed. The satellite instruments and experiments are described, including the Differential Microwave Radiometer, which measures the difference between microwave radiation emitted from two points on the sky, the Far-Infrared Absolute Spectrophotometer, which compares the spectrum of radiation from the sky at wavelengths from 100 microns to one cm with that from an internal blackbody, and the Diffuse Infrared Background Experiment, which searches for the radiation from the earliest generation of stars.

  8. THE COSMIC INFRARED BACKGROUND EXPERIMENT (CIBER): THE WIDE-FIELD IMAGERS

    SciTech Connect

    Bock, J.; Battle, J.; Sullivan, I.; Arai, T.; Matsumoto, T.; Matsuura, S.; Tsumura, K.; Cooray, A.; Mitchell-Wynne, K.; Smidt, J.; Hristov, V.; Lam, A. C.; Levenson, L. R.; Mason, P.; Keating, B.; Renbarger, T.; Kim, M. G.; Lee, D. H.; Nam, U. W.; Suzuki, K.; and others

    2013-08-15

    We have developed and characterized an imaging instrument to measure the spatial properties of the diffuse near-infrared extragalactic background light (EBL) in a search for fluctuations from z > 6 galaxies during the epoch of reionization. The instrument is part of the Cosmic Infrared Background Experiment (CIBER), designed to observe the EBL above Earth's atmosphere during a suborbital sounding rocket flight. The imaging instrument incorporates a 2 Degree-Sign Multiplication-Sign 2 Degree-Sign field of view to measure fluctuations over the predicted peak of the spatial power spectrum at 10 arcmin, and 7'' Multiplication-Sign 7'' pixels, to remove lower redshift galaxies to a depth sufficient to reduce the low-redshift galaxy clustering foreground below instrumental sensitivity. The imaging instrument employs two cameras with {Delta}{lambda}/{lambda} {approx} 0.5 bandpasses centered at 1.1 {mu}m and 1.6 {mu}m to spectrally discriminate reionization extragalactic background fluctuations from local foreground fluctuations. CIBER operates at wavelengths where the electromagnetic spectrum of the reionization extragalactic background is thought to peak, and complements fluctuation measurements by AKARI and Spitzer at longer wavelengths. We have characterized the instrument in the laboratory, including measurements of the sensitivity, flat-field response, stray light performance, and noise properties. Several modifications were made to the instrument following a first flight in 2009 February. The instrument performed to specifications in three subsequent flights, and the scientific data are now being analyzed.

  9. The cosmic background explorer

    SciTech Connect

    Gulkis, G. ); Lubin, P.M. ); Meyer, S.S. ); Silverberg, R.F.

    1990-01-01

    Late last year the National Aeronautics and Space Administration launched its first satellite dedicated to the study of phenomena related to the origins of the universe. The satellite, called the Cosmic Background Explorer (COBE), carries three complementary detectors that will make fundamental measurements of the celestial radiation. Part of that radiation is believed to have originated in processes that occurred at the very dawn of the universe. By measuring the remnant radiation at wavelengths from one micrometer to one centimeter across the entire sky, scientists hope to be able to solve many mysteries regarding the origin and evolution of the early universe. Unfortunately, these radiative relics of the early universe are weak and veiled by local astrophysical and terrestrial sources of radiation. The wavelengths of the various cosmic components may also overlap, thereby making the understanding of the diffuse celestial radiation a challenge. Nevertheless, the COBE instruments, with their full-sky coverage, high sensitivity to a wide range of wavelengths and freedom from interference from the earth's atmosphere, will constitute for astrophysicists an observatory of unprecedented sensitivity and scope. The interesting cosmic signals will then be separated from one another and from noncosmic radiation sources by a comprehensive analysis of the data.

  10. Nonthermal cosmic neutrino background

    NASA Astrophysics Data System (ADS)

    Chen, Mu-Chun; Ratz, Michael; Trautner, Andreas

    2015-12-01

    We point out that, for Dirac neutrinos, in addition to the standard thermal cosmic neutrino background (C ν B ), there could also exist a nonthermal neutrino background with comparable number density. As the right-handed components are essentially decoupled from the thermal bath of standard model particles, relic neutrinos with a nonthermal distribution may exist until today. The relic density of the nonthermal (nt) background can be constrained by the usual observational bounds on the effective number of massless degrees of freedom Neff and can be as large as nν nt≲0.5 nγ. In particular, Neff can be larger than 3.046 in the absence of any exotic states. Nonthermal relic neutrinos constitute an irreducible contribution to the detection of the C ν B and, hence, may be discovered by future experiments such as PTOLEMY. We also present a scenario of chaotic inflation in which a nonthermal background can naturally be generated by inflationary preheating. The nonthermal relic neutrinos, thus, may constitute a novel window into the very early Universe.

  11. Observations of Galactic star-forming regions with the Cosmic Background Imager at 31 GHz

    NASA Astrophysics Data System (ADS)

    Demetroullas, C.; Dickinson, C.; Stamadianos, D.; Harper, S. E.; Cleary, K.; Jones, Michael E.; Pearson, T. J.; Readhead, A. C. S.; Taylor, Angela C.

    2015-10-01

    Studies of the diffuse Galactic radio emission are interesting both for better understanding the physical conditions in our Galaxy and for minimizing the contamination in cosmological measurements. Motivated by this, we present Cosmic Background Imager 31 GHz observations of the Galactic regions NGC 6357, NGC 6334, W51 and W40 at ˜4.5 arcmin resolution and conduct an investigation of the spectral emission process in the regions at 4.5 arcmin and 1° resolution. We find that most of the emission in the regions is due to optically thin free-free. For two sub-regions of NGC 6334 and for a sub-region of W51 though, at 4.5 arcmin resolution and at 31 GHz we detect less emission than expected from extrapolation of radio data at lower frequencies assuming a spectral index of -0.12 for optically thin free-free emission, at 3.3σ, 3.7σ and 6.5σ, respectively. We also detect excess emission in a sub-region of NCG 6334 at 6.4σ, after ruling out any possible contribution from ultra-compact H II regions. At 1° resolution, we detect a spinning dust component in the spectral energy distribution of W40 that accounts for 18 ± 7 per cent of the total flux density in the region at the peak frequency of 37 GHz. Comparison with 100 μm data indicates an average dust emissivity for the sub-regions of 0.5 ± 4.4 μK(MJy sr-1)-1. Finally, we translate the excess emission in the regions to an anomalous microwave emission (AME) emissivity relative to the optical depth at 250 μm. We find that this form of emissivity is independent of the AME significance and has a value somewhere in the order of 104 Jy.

  12. A cosmic microwave background feature consistent with a cosmic texture.

    PubMed

    Cruz, M; Turok, N; Vielva, P; Martínez-González, E; Hobson, M

    2007-12-01

    The Cosmic Microwave Background provides our most ancient image of the universe and our best tool for studying its early evolution. Theories of high-energy physics predict the formation of various types of topological defects in the very early universe, including cosmic texture, which would generate hot and cold spots in the Cosmic Microwave Background. We show through a Bayesian statistical analysis that the most prominent 5 degrees -radius cold spot observed in all-sky images, which is otherwise hard to explain, is compatible with having being caused by a texture. From this model, we constrain the fundamental symmetry-breaking energy scale to be (0) approximately 8.7 x 10(15) gigaelectron volts. If confirmed, this detection of a cosmic defect will probe physics at energies exceeding any conceivable terrestrial experiment. PMID:17962521

  13. Diffuse Cosmic Infrared Background Radiation

    NASA Technical Reports Server (NTRS)

    Dwek, Eli

    2002-01-01

    The diffuse cosmic infrared background (CIB) consists of the cumulative radiant energy released in the processes of structure formation that have occurred since the decoupling of matter and radiation following the Big Bang. In this lecture I will review the observational data that provided the first detections and limits on the CIB, and the theoretical studies explaining the origin of this background. Finally, I will also discuss the relevance of this background to the universe as seen in high energy gamma-rays.

  14. The cosmic microwave background radiation

    NASA Technical Reports Server (NTRS)

    Silk, Joseph

    1992-01-01

    A review the implications of the spectrum and anisotropy of the cosmic microwave background for cosmology. Thermalization and processes generating spectral distortions are discussed. Anisotropy predictions are described and compared with observational constraints. If the evidence for large-scale power in the galaxy distribution in excess of that predicted by the cold dark matter model is vindicated, and the observed structure originated via gravitational instabilities of primordial density fluctuations, the predicted amplitude of microwave background anisotropies on angular scales of a degree and larger must be at least several parts in 10 exp 6.

  15. Cosmic Infrared Background Fluctuations in Deep Spitzer Infrared Array Camera Images: Data Processing and Analysis

    NASA Technical Reports Server (NTRS)

    Arendt, Richard; Kashlinsky, A.; Moseley, S.; Mather, J.

    2010-01-01

    This paper provides a detailed description of the data reduction and analysis procedures that have been employed in our previous studies of spatial fluctuation of the cosmic infrared background (CIB) using deep Spitzer Infrared Array Camera observations. The self-calibration we apply removes a strong instrumental signal from the fluctuations that would otherwise corrupt the results. The procedures and results for masking bright sources and modeling faint sources down to levels set by the instrumental noise are presented. Various tests are performed to demonstrate that the resulting power spectra of these fields are not dominated by instrumental or procedural effects. These tests indicate that the large-scale ([greater, similar]30') fluctuations that remain in the deepest fields are not directly related to the galaxies that are bright enough to be individually detected. We provide the parameterization of these power spectra in terms of separate instrument noise, shot noise, and power-law components. We discuss the relationship between fluctuations measured at different wavelengths and depths, and the relations between constraints on the mean intensity of the CIB and its fluctuation spectrum. Consistent with growing evidence that the [approx]1-5 [mu]m mean intensity of the CIB may not be as far above the integrated emission of resolved galaxies as has been reported in some analyses of DIRBE and IRTS observations, our measurements of spatial fluctuations of the CIB intensity indicate the mean emission from the objects producing the fluctuations is quite low ([greater, similar]1 nW m-2 sr-1 at 3-5 [mu]m), and thus consistent with current [gamma]-ray absorption constraints. The source of the fluctuations may be high-z Population III objects, or a more local component of very low luminosity objects with clustering properties that differ from the resolved galaxies. Finally, we discuss the prospects of the upcoming space-based surveys to directly measure the epochs

  16. Cosmic Microwave Background Data Analysis

    NASA Astrophysics Data System (ADS)

    Paykari, Paniez; Starck, Jean-Luc Starck

    2012-03-01

    that the highest power fluctuations occur at scales of about one degree. A number of ground-based interferometers provided measurements of the fluctuations with higher accuracy over the next three years, including the Very Small Array [16], Degree Angular Scale Interferometer (DASI) [61], and the Cosmic Background Imager (CBI) [78]. DASI was the first to detect the polarization of the CMB and the CBI provided the first E-mode polarization spectrum with compelling evidence that it is out of phase with the T-mode spectrum. In June 2001, NASA launched its second CMB mission (after COBE), Wilkinson Microwave Anisotropy Explorer (WMAP) [44], to make much more precise measurements of the CMB sky. WMAP measured the differences in the CMB temperature across the sky creating a full-sky map of the CMB in five different frequency bands. The mission also measured the CMB's E-mode and the foreground polarization. As of October 2010, the WMAP spacecraft has ended its mission after nine years of operation. Although WMAP provided very accurate measurements of the large angular-scale fluctuations in the CMB, it did not have the angular resolution to cover the smaller-scale fluctuations that had been observed by previous ground-based interferometers. A third space mission, the Planck Surveyor [1], was launched by ESA* in May 2009 to measure the CMB on smaller scales than WMAP, as well as making precise measurements of the polarization of CMB. Planck represents an advance over WMAP in several respects: it observes in higher resolution, hence allowing one to probe the CMB power spectrum to smaller scales; it has a higher sensitivity and observes in nine frequency bands rather than five, hence improving the astrophysical foreground models. The mission has a wide variety of scientific aims, including: (1) detecting the total intensity/polarization of the primordial CMB anisotropies; (2) creating a galaxy-cluster catalogue through the Sunyaev-Zel'dovich (SZ) effect [93]; (3) observing the

  17. [Cosmic Microwave Background (CMB) Anisotropies

    NASA Technical Reports Server (NTRS)

    Silk, Joseph

    1998-01-01

    One of the main areas of research is the theory of cosmic microwave background (CMB) anisotropies and analysis of CMB data. Using the four year COBE data we were able to improve existing constraints on global shear and vorticity. We found that, in the flat case (which allows for greatest anisotropy), (omega/H)0 less than 10(exp -7), where omega is the vorticity and H is the Hubble constant. This is two orders of magnitude lower than the tightest, previous constraint. We have defined a new set of statistics which quantify the amount of non-Gaussianity in small field cosmic microwave background maps. By looking at the distribution of power around rings in Fourier space, and at the correlations between adjacent rings, one can identify non-Gaussian features which are masked by large scale Gaussian fluctuations. This may be particularly useful for identifying unresolved localized sources and line-like discontinuities. Levin and collaborators devised a method to determine the global geometry of the universe through observations of patterns in the hot and cold spots of the CMB. We have derived properties of the peaks (maxima) of the CMB anisotropies expected in flat and open CDM models. We represent results for angular resolutions ranging from 5 arcmin to 20 arcmin (antenna FWHM), scales that are relevant for the MAP and COBRA/SAMBA space missions and the ground-based interferometer. Results related to galaxy formation and evolution are also discussed.

  18. [Cosmic Microwave Background (CMB) Anisotropies

    NASA Astrophysics Data System (ADS)

    Silk, Joseph

    1998-01-01

    One of the main areas of research is the theory of cosmic microwave background (CMB) anisotropies and analysis of CMB data. Using the four year COBE data we were able to improve existing constraints on global shear and vorticity. We found that, in the flat case (which allows for greatest anisotropy), (omega/H)0 less than 10-7, where omega is the vorticity and H is the Hubble constant. This is two orders of magnitude lower than the tightest, previous constraint. We have defined a new set of statistics which quantify the amount of non-Gaussianity in small field cosmic microwave background maps. By looking at the distribution of power around rings in Fourier space, and at the correlations between adjacent rings, one can identify non-Gaussian features which are masked by large scale Gaussian fluctuations. This may be particularly useful for identifying unresolved localized sources and line-like discontinuities. Levin and collaborators devised a method to determine the global geometry of the universe through observations of patterns in the hot and cold spots of the CMB. We have derived properties of the peaks (maxima) of the CMB anisotropies expected in flat and open CDM models. We represent results for angular resolutions ranging from 5 arcmin to 20 arcmin (antenna FWHM), scales that are relevant for the MAP and COBRA/SAMBA space missions and the ground-based interferometer. Results related to galaxy formation and evolution are also discussed.

  19. Polarization of Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Buzzelli, A.; Cabella, P.; de Gasperis, G.; Vittorio, N.

    2016-02-01

    In this work we present an extension of the ROMA map-making code for data analysis of Cosmic Microwave Background polarization, with particular attention given to the inflationary polarization B-modes. The new algorithm takes into account a possible cross- correlated noise component among the different detectors of a CMB experiment. We tested the code on the observational data of the BOOMERanG (2003) experiment and we show that we are provided with a better estimate of the power spectra, in particular the error bars of the BB spectrum are smaller up to 20% for low multipoles. We point out the general validity of the new method. A possible future application is the LSPE balloon experiment, devoted to the observation of polarization at large angular scales.

  20. The pregalactic cosmic gravitational wave background

    NASA Technical Reports Server (NTRS)

    Matzner, Richard A.

    1989-01-01

    An outline is given that estimates the expected gravitational wave background, based on plausible pregalactic sources. Some cosmologically significant limits can be put on incoherent gravitational wave background arising from pregalactic cosmic evolution. The spectral region of cosmically generated and cosmically limited radiation is, at long periods, P greater than 1 year, in contrast to more recent cosmological sources, which have P approx. 10 to 10(exp -3).

  1. Searching for Cosmic Strings in the Cosmic Microwave Background:

    NASA Astrophysics Data System (ADS)

    Wu, Jiun-Huei Proty

    The role of cosmic defects in cosmology is entering its new phase—as a test for several fundamental physics, including unification theories and inflation. We discuss how to use the Cosmic Microwave Background (CMB) to detect cosmic strings, a type of cosmic defects, and how to use this result to constrain the underlying physics. In particular, we use the simulations for the Array for Microwave Background Anisotropy (AMiBA) to demonstrate the power of this approach. The required resolution and sensitivity in such a method are discussed, and so is the possible scientific impact.

  2. Cosmic Background Explorer (COBE) press kit

    NASA Technical Reports Server (NTRS)

    1989-01-01

    COBE, the Cosmic Background Explorer spacecraft, and its mission are described. COBE was designed to study the origin and dynamics of the universe including the theory that the universe began with a cataclysmic explosion referred to as the Big Bang. To this end, earth's cosmic background - the infrared radiation that bombards earth from every direction - will be measured by three sophisticated instruments: the Differential Microwave Radiometer (DMR), the Far Infrared Absolute Spectrophotometer (FIRAS), and the Diffuse Infrared Background Experiment (DIRBE).

  3. Cosmic-ray backgrounds in infrared bolometers

    NASA Technical Reports Server (NTRS)

    Nolt, I. G.; Radostitz, J. V.; Carlotti, M.; Carli, B.; Mencaraglia, F.

    1985-01-01

    Model calculations for the production of cosmic ray events in IR detectors by energy impulses due to fast charged particles' ionization trails are presently compared to the pulse-amplitude spectrum observed from a balloon at an altitude of 38 km. The results are pertinent to the current understanding of cosmic ray backgrounds found in all high sensitivity bolometer applications. The observed signal transients are in all details consistent with the modeling of known cosmic charged particle flux characteristics and with the detector response. Generally, the optics design should minimize detector/substrate cross section.

  4. Spectral distortions of the cosmic microwave background

    NASA Technical Reports Server (NTRS)

    Adams, Fred C.; Mcdowell, Jonathan C.; Freese, Katherine; Levin, Janna

    1989-01-01

    Recent experiments indicate that the spectrum of the cosmic microwave background deviates from a pure blackbody; here, spectral distortions produced by cosmic dust are considered. The main result is that cosmic dust in conjunction with an injected radiation field (perhaps produced by an early generation of very massive stars) can explain the observed spectral distortions without violating existing cosmological constraints. In addition, it is shown that Compton y-distortions can also explain the observed spectral shape, but the energetic requirements are more severe.

  5. Cosmic microwave background probes models of inflation

    NASA Technical Reports Server (NTRS)

    Davis, Richard L.; Hodges, Hardy M.; Smoot, George F.; Steinhardt, Paul J.; Turner, Michael S.

    1992-01-01

    Inflation creates both scalar (density) and tensor (gravity wave) metric perturbations. We find that the tensor-mode contribution to the cosmic microwave background anisotropy on large-angular scales can only exceed that of the scalar mode in models where the spectrum of perturbations deviates significantly from scale invariance. If the tensor mode dominates at large-angular scales, then the value of DeltaT/T predicted on 1 deg is less than if the scalar mode dominates, and, for cold-dark-matter models, bias factors greater than 1 can be made consistent with Cosmic Background Explorer (COBE) DMR results.

  6. The cosmic mult-messenger background field

    NASA Astrophysics Data System (ADS)

    Hartmann, Dieter

    2016-04-01

    The cosmic star formation history associated with baryon flows within the large scale structure of the expanding Universe has many important consequences, such as cosmic chemical- and galaxy evolution. Stars and accreting compact objects subsequently produce light, from the radio band to the highest photon energies, and dust within galaxies reprocesses a significant fraction of this light into the IR region. The Universe creates a radiation background that adds to the relic field from the big bang, the CMB. In addition, Cosmic Rays are created on variouys scales, and interact with this diffuse radiation field, and neutrinos are added as well. A multi-messenger field is created whose evolution with redshift contains a tremendous amount of cosmological information. We discuss several aspects of this story, emphasizing the background in the HE regime and the neutrino sector, and disccus the use of gamma-ray sources as probes.

  7. Measuring anisotropies in the cosmic neutrino background

    NASA Astrophysics Data System (ADS)

    Lisanti, Mariangela; Safdi, Benjamin R.; Tully, Christopher G.

    2014-10-01

    Neutrino capture on tritium has emerged as a promising method for detecting the cosmic neutrino background (C ν B ). We show that relic neutrinos are captured most readily when their spin vectors are antialigned with the polarization axis of the tritium nuclei and when they approach along the direction of polarization. As a result, C ν B observatories may measure anisotropies in the cosmic neutrino velocity and spin distributions by polarizing the tritium targets. A small dipole anisotropy in the C ν B is expected due to the peculiar velocity of the lab frame with respect to the cosmic frame and due to late-time gravitational effects. The PTOLEMY experiment, a tritium observatory currently under construction, should observe a nearly isotropic background. This would serve as a strong test of the cosmological origin of a potential signal. The polarized-target measurements may also constrain nonstandard neutrino interactions that would induce larger anisotropies and help discriminate between Majorana versus Dirac neutrinos.

  8. Cosmic Background Explorer (COBE): Emergency support

    NASA Technical Reports Server (NTRS)

    Stanford, R.; Mattson, R.

    1991-01-01

    The Cosmic Background Explorer (COBE) Mission will measure the diffuse radiation from the universe in the wavelength band 1 micron to 9.6 mm. The band includes the 3 K cosmic background radiation, the known relic of the primeval cosmic explosion. The COBE satellite will be launched from the Western Space and Missile Center (EWSMC) via a Delta launch vehicle into a circular parking orbit of about 300 km. COBE will be placed into a 900-km altitude circular orbit. Coverage will be provided by the Deep Space Network (DSN) for COBE emergencies that would prevent communications via the normal channels of the Tracking and Data Relay Satellite System (TDRSS). Emergency support will be provided by the DSN 26-m subnetwork. Information is given in tabular form for DSN network support, frequency assignments, telemetry, and command.

  9. Search for the Cosmic Neutrino Background

    NASA Astrophysics Data System (ADS)

    Faessler, A.; Hodak, R.; Kovalenko, S.; Simkovic, F.

    2015-02-01

    One expects three Cosmic Backgrounds: (1) The Cosmic Microwave Background (CMB) originated 380000 years after the Big Bang (BB). (2) The Neutrino Background decoupled about one second after the BB, while (3) the Cosmic Gravitational Wave Background created by the inflationary expansion decoupled directly after the BB. Only the Cosmic Microwave Background (CMB) has been detected and is well studied. Its spectrum follows Planck's black body radiation formula and shows a remarkable constant temperature of T0γ ≈ 2.7 K independent of the direction. The present photon density is about 370 photons per cm3. The size of the hot spots, which deviates only in the fifth decimal of the temperature from the average value, tells us, that the universe is flat. About 380 000 years after the Big Bang at a temperature of T0γ = 3000 K already in the matter dominated era the electrons combine with the protons and 4He and the photons move freely in the neutral universe and form the CMB. So the temperature and distribution of the photons give us information of the universe 380 000 years after the Big Bang. The Cosmic Neutrino Background (CνB) decoupled from matter already one second after the BB at a temperature of about 1010 K. Today their temperature is ~ 1.95 K and the average density is 56 electron-neutrinos and the total density of all neutrinos about 336 per cm3. Measurement of these neutrinos is an extremely challenging experimental problem which can hardly be solved with the present technologies. On the other hand it represents a tempting opportunity to check one of the key elements of the Big Bang Cosmology and to probe the early stages of the universe. The search for the CνB with the induced beta decay νe+3H → 3He + e- using KATRIN (KArlsruhe TRItium Neutrino experiment) is the topic of this contribution.

  10. Cosmic Microwave Background spectral distortions from cosmic string loops

    NASA Astrophysics Data System (ADS)

    Anthonisen, Madeleine; Brandenberger, Robert; Laguë, Alex; Morrison, Ian A.; Xia, Daixi

    2016-02-01

    Cosmic string loops contain cusps which decay by emitting bursts of particles. A significant fraction of the released energy is in the form of photons. These photons are injected non-thermally and can hence cause spectral distortions of the Cosmic Microwave Background (CMB). Under the assumption that cusps are robust against gravitational back-reaction, we compute the fractional energy density released as photons in the redshift interval where such non-thermal photon injection causes CMB spectral distortions. Whereas current constraints on such spectral distortions are not strong enough to constrain the string tension, future missions such as the PIXIE experiment will be able to provide limits which rule out a range of string tensions between G μ ~ 10-15 and G μ ~ 10-12, thus ruling out particle physics models yielding these kind of intermediate-scale cosmic strings.

  11. Fitting cosmic microwave background data with cosmic strings and inflation.

    PubMed

    Bevis, Neil; Hindmarsh, Mark; Kunz, Martin; Urrestilla, Jon

    2008-01-18

    We perform a multiparameter likelihood analysis to compare measurements of the cosmic microwave background (CMB) power spectra with predictions from models involving cosmic strings. Adding strings to the standard case of a primordial spectrum with power-law tilt ns, we find a 2sigma detection of strings: f10=0.11+/-0.05, where f10 is the fractional contribution made by strings in the temperature power spectrum (at l=10). CMB data give moderate preference to the model ns=1 with cosmic strings over the standard zero-strings model with variable tilt. When additional non-CMB data are incorporated, the two models become on a par. With variable ns and these extra data, we find that f10<0.11, which corresponds to Gmicro<0.7x10(-6) (where micro is the string tension and G is the gravitational constant). PMID:18232848

  12. Precision measurements of the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    de Bernardis, Paolo; Masi, Silvia; Wuensche, Carlos Alexandre

    2015-12-01

    Precision measurements of the Cosmic Microwave Background (CMB) sample the entire history of the Universe. In this paper we give a short review, from the experimentalist point of view, of the current status and of what can still be done, using this extraordinary tool, to investigate cosmology and fundamental physics.

  13. THE TEMPERATURE OF THE COSMIC MICROWAVE BACKGROUND

    SciTech Connect

    Fixsen, D. J.

    2009-12-20

    The Far InfraRed Absolute Spectrophotometer data are independently recalibrated using the Wilkinson Microwave Anisotropy Probe data to obtain a cosmic microwave background (CMB) temperature of 2.7260 +- 0.0013. Measurements of the temperature of the CMB are reviewed. The determination from the measurements from the literature is CMB temperature of 2.72548 +- 0.00057 K.

  14. Cosmic string collision in cosmological backgrounds

    SciTech Connect

    Firouzjahi, Hassan; Khoeini-Moghaddam, Salomeh; Khosravi, Shahram

    2010-06-15

    The collisions of cosmic string loops and the dynamics of junction formations in expanding backgrounds are studied. The key parameter controlling the dynamics of junction formation, the cosmic strings zipping and unzipping, is the relative size of the loops compared to the Hubble radius at the time of collision. We study analytically and numerically these processes for large superhorizon size loops, for small subhorizon size loops as well as for loops with the radii comparable to the Hubble radius at the time of collision.

  15. Neutrino refraction by the cosmic neutrino background

    NASA Astrophysics Data System (ADS)

    Díaz, J. S.; Klinkhamer, F. R.

    2016-03-01

    We have determined the dispersion relation of a neutrino test particle propagating in the cosmic neutrino background. Describing the relic neutrinos and antineutrinos from the hot big bang as a dense medium, a matter potential or refractive index is obtained. The vacuum neutrino mixing angles are unchanged, but the energy of each mass state is modified. Using a matrix in the space of neutrino species, the induced potential is decomposed into a part which produces signatures in beta-decay experiments and another part which modifies neutrino oscillations. The low temperature of the relic neutrinos makes a direct detection extremely challenging. From a different point of view, the identified refractive effects of the cosmic neutrino background constitute an ultralow background for future experimental studies of nonvanishing Lorentz violation in the neutrino sector.

  16. Characterizing the Cosmic Infrared Background Fluctuations

    NASA Astrophysics Data System (ADS)

    Li, Yanxia; Hasinger, Guenther; Cappelluti, Nico; Cappelluti, Nico; Arendt, Richard G.

    2016-01-01

    A salient feature of the Cosmic Infrared Background (CIB) fluctuations is that their spatial power spectrum rises a factor of ~10 above the expected contribution from all known sources at angular scales >20". A tantalizing large-scale correlation signal between the residual Cosmic X-ray Background (CXB) and CIB found in the Extended Groth Strip (EGS) further suggests that at least 20% of the CIB fluctuations are associated with accreting X-ray sources, with efficient energy production similar to black holes. However, there is still a controversy about the sources that produce the excess flux. They could be faint, local populations with different spatial distribution from other known galaxies, or high-z populations at the epoch of reionization that we know little of. Constraining the origin of the CIB fluctuations will help to establish our understanding of the overall cosmic energy budget. We will combine the archival Spitzer/IRAC and the Chandra data of the Cosmic Evolution Survey (COSMOS), to accurately measure the source-subtracted CIB and CXB fluctuations to the largest angular scale (~1-2 deg) to date. The newly discovered link between CIB and CXB fluctuations found in the EGS will be revisited in the COSMOS, which provides better photon statistics. We will present current state of data collection and analysis progress.

  17. A Detector for Cosmic Microwave Background Polarimetry

    NASA Technical Reports Server (NTRS)

    Wollack, E.; Cao, N.; Chuss, D.; Hsieh, W.-T.; Moseley, S. Harvey; Stevenson, T.; U-yen, K.

    2008-01-01

    We present preliminary design and development work on polarized detectors intended to enable Cosmic Microwave Background polarization measurements that will probe the first moments of the universe. The ultimate measurement will be challenging, requiring background-limited detectors and good control of systematic errors. Toward this end, we are integrating the beam control of HE-11 feedhorns with the sensitivity of transition-edge sensors. The coupling between these two devices is achieved via waveguide probe antennas and superconducting microstrip lines. This implementation allows band-pass filters to be incorporated on the detector chip. We believe that a large collection of single-mode polarized detectors will eventually be required for the reliable detection of the weak polarized signature that is expected to result from gravitational waves produced by cosmic inflation. This focal plane prototype is an important step along the path to this detection, resulting in a capability that will enable various future high performance instrument concepts.

  18. Characterizing the Cosmic Infrared Background Fluctuations

    NASA Astrophysics Data System (ADS)

    Li, Yanxia

    2015-08-01

    A salient feature of the Cosmic Infrared Background (CIB) fluctuations is that their spatial power spectrum rises a factor of ~10 above the expected contribution from all known sources at angular scales >20‧‧. A tantalizing large-scale correlation signal between the residual Cosmic X-ray Background (CXB) and CIB found in the Extended Groth Strip (EGS) further suggests that at least 20% of the CIB fluctuations are associated with accreting X-ray sources, with efficient energy production similar to black holes. However, there is still a controversy about the sources that produce the excess flux. They could be faint, local populations with different spatial distribution from other known galaxies, e.g., intra-halo light (emitted from stars in the outskirts of local galaxies), or really high-z populations at the epoch of reionization that we know little of. Constraining the origin of the CIB fluctuations will help to establish our understanding of the overall cosmic energy budget.In this talk, we will present our plan to break down this controversy, current state of data collection and analysis.(1) We will combine the archival Spitzer/IRAC and Herschel/PACS data, with the Chandra data of the Cosmic Evolution Survey (COSMOS), to accurately measure the source-subtracted CIB and CXB fluctuations to the largest angular scale (~1-2 deg) to date. The newly discovered link between CIB and CXB fluctuations found in the EGS will be revisited in the COSMOS, which provides better photon statistics. (2) We have been working on cross-correlating the unresolved background with the discrete sources detected at shorter wavelengths (1- 2μm), using ground-based multi-wavelength observations. In addition to exploring the Pan-STARRS 3PI and Medium Deep Survey database, we have also been awarded the telescope time of CFHT/WIRCam and Subaru/Hyper-Suprime-Cam for this purpose. The preliminary data analysis will be presented.

  19. Detection prospects of the cosmic neutrino background

    NASA Astrophysics Data System (ADS)

    Li, Yu-Feng

    2015-04-01

    The existence of the cosmic neutrino background (CνB) is a fundamental prediction of the standard Big Bang cosmology. Although current cosmological probes provide indirect observational evidence, the direct detection of the CνB in a laboratory experiment is a great challenge to the present experimental techniques. We discuss the future prospects for the direct detection of the CνB, with the emphasis on the method of captures on beta-decaying nuclei and the PTOLEMY project. Other possibilities using the electron-capture (EC) decaying nuclei, the annihilation of extremely high-energy cosmic neutrinos (EHECνs) at the Z-resonance, and the atomic de-excitation method are also discussed in this review (talk given at the International Conference on Massive Neutrinos, Singapore, 9-13 February 2015).

  20. Detection Prospects of the Cosmic Neutrino Background

    NASA Astrophysics Data System (ADS)

    Li, Yu-Feng

    The existence of the cosmic neutrino background (CνB) is a fundamental prediction of the standard Big Bang cosmology. Although current cosmological probes provide indirect observational evidence, the direct detection of the CνB in a laboratory experiment is a great challenge to the present experimental techniques. We discuss the future prospects for the direct detection of the CνB, with the emphasis on the method of captures on beta-decaying nuclei and the PTOLEMY project. Other possibilities using the electron-capture (EC) decaying nuclei, the annihilation of extremely high-energy cosmic neutrinos (EHECνs) at the Z-resonance, and the atomic de-excitation method are also discussed in this review.

  1. Ponderable soliton stars and cosmic background radiation

    NASA Technical Reports Server (NTRS)

    Chiu, Hong-Yee

    1990-01-01

    A theory is developed to describe the possible perturbations of the cosmic background radiation (CBR) by radiation from ponderable soliton stars in the early universe. Since the temperature of such stars is in the range of 10 to the 6th K, thermalization of their emitted radiation is possible. Two models are considered: one in which thermalization is ignored and one in which decoupling from thermalization is considered as a sudden process. The expected perturbation of the CBR is probably less than 1 percent and is largely around the short-wavelength end, in the form of point radio sources. This result is consistent with the most recent COBE measurements.

  2. Signatures of a hidden cosmic microwave background.

    PubMed

    Jaeckel, Joerg; Redondo, Javier; Ringwald, Andreas

    2008-09-26

    If there is a light Abelian gauge boson gamma' in the hidden sector its kinetic mixing with the photon can produce a hidden cosmic microwave background (HCMB). For meV masses, resonant oscillations gamma<-->gamma' happen after big bang nucleosynthesis (BBN) but before CMB decoupling, increasing the effective number of neutrinos Nnu(eff) and the baryon to photon ratio, and distorting the CMB blackbody spectrum. The agreement between BBN and CMB data provides new constraints. However, including Lyman-alpha data, Nnu(eff) > 3 is preferred. It is tempting to attribute this effect to the HCMB. The interesting parameter range will be tested in upcoming laboratory experiments. PMID:18851438

  3. Measurements of the cosmic background radiation

    NASA Technical Reports Server (NTRS)

    Lubin, P.; Villela, T.

    1987-01-01

    Maps of the large scale structure (theta is greater than 6 deg) of the cosmic background radiation covering 90 percent of the sky are now available. The data show a very strong 50-100 sigma (statistical error) dipole component, interpreted as being due to our motion, with a direction of alpha = 11.5 + or - 0.15 hours, sigma = -5.6 + or - 2.0 deg. The inferred direction of the velocity of our galaxy relative to the cosmic background radiation is alpha = 10.6 + or - 0.3 hours, sigma = -2.3 + or - 5 deg. This is 44 deg from the center of the Virgo cluster. After removing the dipole component, the data show a galactic signature but no apparent residual structure. An autocorrelation of the residual data, after substraction of the galactic component from a combined Berkeley (3 mm) and Princeton (12 mm) data sets, show no apparent structure from 10 to 180 deg with a rms of 0.01 mK(sup 2). At 90 percent confidence level limit of .00007 is placed on a quadrupole component.

  4. Cosmic axion background propagation in galaxies

    NASA Astrophysics Data System (ADS)

    Day, Francesca V.

    2016-02-01

    Many extensions of the Standard Model include axions or axion-like particles (ALPs). Here we study ALP to photon conversion in the magnetic field of the Milky Way and starburst galaxies. By modelling the effects of the coherent and random magnetic fields, the warm ionized medium and the warm neutral medium on the conversion process, we simulate maps of the conversion probability across the sky for a range of ALP energies. In particular, we consider a diffuse cosmic ALP background (CAB) analogous to the CMB, whose existence is suggested by string models of inflation. ALP-photon conversion of a CAB in the magnetic fields of galaxy clusters has been proposed as an explanation of the cluster soft X-ray excess. We therefore study the phenomenology and expected photon signal of CAB propagation in the Milky Way. We find that, for the CAB parameters required to explain the cluster soft X-ray excess, the photon flux from ALP-photon conversion in the Milky Way would be unobservably small. The ALP-photon conversion probability in galaxy clusters is 3 orders of magnitude higher than that in the Milky Way. Furthermore, the morphology of the unresolved cosmic X-ray background is incompatible with a significant component from ALP-photon conversion. We also consider ALP-photon conversion in starburst galaxies, which host much higher magnetic fields. By considering the clumpy structure of the galactic plasma, we find that conversion probabilities comparable to those in clusters may be possible in starburst galaxies.

  5. Bayesian Analysis of the Cosmic Microwave Background

    NASA Technical Reports Server (NTRS)

    Jewell, Jeffrey

    2007-01-01

    There is a wealth of cosmological information encoded in the spatial power spectrum of temperature anisotropies of the cosmic microwave background! Experiments designed to map the microwave sky are returning a flood of data (time streams of instrument response as a beam is swept over the sky) at several different frequencies (from 30 to 900 GHz), all with different resolutions and noise properties. The resulting analysis challenge is to estimate, and quantify our uncertainty in, the spatial power spectrum of the cosmic microwave background given the complexities of "missing data", foreground emission, and complicated instrumental noise. Bayesian formulation of this problem allows consistent treatment of many complexities including complicated instrumental noise and foregrounds, and can be numerically implemented with Gibbs sampling. Gibbs sampling has now been validated as an efficient, statistically exact, and practically useful method for low-resolution (as demonstrated on WMAP 1 and 3 year temperature and polarization data). Continuing development for Planck - the goal is to exploit the unique capabilities of Gibbs sampling to directly propagate uncertainties in both foreground and instrument models to total uncertainty in cosmological parameters.

  6. Introductory Remarks to Cosmic Background Parallel Sessions.

    NASA Astrophysics Data System (ADS)

    Burigana, Carlo; de Bernardis, Paolo; Masi, Silvia; Norgaard-Nielsen, Hans Ulrik

    2015-01-01

    These are promising times for the study of cosmic microwave background and foregrounds. While, at the date of this meeting, WMAP is close to release its final maps and products, Planck early and intermediate results have been presented with the first release of the compact source catalog, and the presentation of the first cosmological products is approaching. This parallel session is focussed on the astrophysical sky as seen by Planck and other observatories, and on their scientific exploitation, regarding diffuse emissions, sources, galaxy clusters, cosmic infrared background, as well as on critical issues coming from systematic effects and data analysis, in the view of fundamental physics and cosmology perspectives. At the same time, a new generation of CMB anisotropy and polarization experiments is currently operated using large arrays of detectors, boosting the sensitivity and resolution of the surveys to unprecedented levels. Mainstream projects are observations of the polarization of the CMB, looking for the inflationary B-modes at large and intermediate angular scales, fine-scale measurements of the Sunyaev-Zel'dovich effect in clusters of galaxies, and the precise measure of CMB spectrum.

  7. Cosmic Microwave Background Polarization and Inflation

    NASA Technical Reports Server (NTRS)

    Chuss, David T.

    2011-01-01

    Measurements of the cosmic microwave background (CMB) offer a means to explore the universe at a very early epoch. Specifically, if the universe went through a brief period of exponential expansion called inflation as current data suggest, gravitational waves from this period would polarize the CMB in a specific pattern. At GSFC, we are currently working towards two experiments that work in concert to measure this polarization pattern in search of evidence for inflation. The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization at frequencies between 40 and 150 GHz from the Atacama Desert in Chile. The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne experiment that will make similar measurements at frequencies between 200 and 600 GHz.

  8. Polarization of the cosmic background radiation

    SciTech Connect

    Lubin, Philip M.; Smoot, George F.

    1980-08-01

    We discuss the technique and results of a measurement of the linear polarization of the Cosmic Background Radiation. Data taken between May 1978 and February 1980 from both the northern hemisphere (Berkeley Lat. 38{sup o}N) and the southern hemisphere (Lima Lat. 12{sup o}s) over 11 declinations from -37{sup o} to +63{sup o} show the radiation to be essentially unpolarized over all areas surveyed. Fitting all data gives the 95% confidence level limit on a linearly polarized component of 0.3 mK for spherical harmonics through third order. A fit of all data to the anisotropic axisymmetric model of Rees (1968) yields a 95% confidence level limit of 0.15 mK for the magnitude of the polarized component. Constraints on various cosmological models are discussed in light of these limits.

  9. The POLARBEAR Cosmic Microwave Background Polarization Experiment

    NASA Astrophysics Data System (ADS)

    Barron, D.; Ade, P.; Anthony, A.; Arnold, K.; Boettger, D.; Borrill, J.; Chapman, S.; Chinone, Y.; Dobbs, M.; Edwards, J.; Errard, J.; Fabbian, G.; Flanigan, D.; Fuller, G.; Ghribi, A.; Grainger, W.; Halverson, N.; Hasegawa, M.; Hattori, K.; Hazumi, M.; Holzapfel, W.; Howard, J.; Hyland, P.; Jaehnig, G.; Jaffe, A.; Keating, B.; Kermish, Z.; Keskitalo, R.; Kisner, T.; Lee, A. T.; Le Jeune, M.; Linder, E.; Lungu, M.; Matsuda, F.; Matsumura, T.; Meng, X.; Miller, N. J.; Morii, H.; Moyerman, S.; Myers, M.; Nishino, H.; Paar, H.; Peloton, J.; Quealy, E.; Rebeiz, G.; Reichardt, C. L.; Richards, P. L.; Ross, C.; Shimizu, A.; Shimmin, C.; Shimon, M.; Sholl, M.; Siritanasak, P.; Spieler, H.; Stebor, N.; Steinbach, B.; Stompor, R.; Suzuki, A.; Tomaru, T.; Tucker, C.; Yadav, A.; Zahn, O.

    2014-09-01

    The polarbear cosmic microwave background (CMB) polarization experiment has been observing since early 2012 from its 5,200 m site in the Atacama Desert in Northern Chile. polarbear's measurements will characterize the expected CMB polarization due to gravitational lensing by large scale structure, and search for the possible B-mode polarization signature of inflationary gravitational waves. polarbear's 250 mK focal plane detector array consists of 1,274 polarization-sensitive antenna-coupled bolometers, each with an associated lithographed band-defining filter and contacting dielectric lenslet, an architecture unique in current CMB experiments. The status of the polarbear instrument, its focal plane, and the analysis of its measurements are presented.

  10. Polarization of the cosmic background radiation

    SciTech Connect

    Lubin, P.M.

    1980-03-01

    The results and technique of a measurement of the linear polarization of the Cosmic Background Radiation are discussed. The ground-based experiment utilizes a single horn (7/sup 0/ beam width) Dicke-type microwave polarimeter operating at 33 GHz (9.1 mm). Data taken between May 1978 and February 1980 from both the northern hemisphere (Berkeley Lat. = 38/sup 0/N) and the southern hemisphere (Lima Lat. = 12/sup 0/S) show the radiation to be essentially unpolarized over all areas surveyed. For the 38/sup 0/ declination data the 95% confidence level limit on a linearly polarized component is 0.3 mK for the average and 12 and 24 hour periods. Fitting all data gives the 95% confidence level limit on a linearly polarized component of 0.3 mK for spherical harmonics through third order. Constraints on various cosmological models are discussed in light of these limits.

  11. Physics of the cosmic microwave background anisotropy

    NASA Astrophysics Data System (ADS)

    Bucher, Martin

    2015-01-01

    Observations of the cosmic microwave background (CMB), especially of its frequency spectrum and its anisotropies, both in temperature and in polarization, have played a key role in the development of modern cosmology and of our understanding of the very early universe. We review the underlying physics of the CMB and how the primordial temperature and polarization anisotropies were imprinted. Possibilities for distinguishing competing cosmological models are emphasized. The current status of CMB experiments and experimental techniques with an emphasis toward future observations, particularly in polarization, is reviewed. The physics of foreground emissions, especially of polarized dust, is discussed in detail, since this area is likely to become crucial for measurements of the B modes of the CMB polarization at ever greater sensitivity.

  12. Cosmic Infrared Background and Early Stellar Populations

    NASA Technical Reports Server (NTRS)

    Kashlinsky, A.

    2005-01-01

    Cosmic infrared background (CIB) contains information about galaxy luminosities over the entire history of the Universe and can be a powerful diagnostic of the early populations otherwise inaccessible to telescopic studies. Its measurements are very difficult because of the strong IR foregrounds from the Solar system and the Galaxy. Nevertheless, substantial recent progress in measuring the CIB and its structure has been made. The measurements now allow to set significant constraints on early galaxy evolution and, perhaps, even detect the elusive Population III era. We discuss briefly the theory behind the CIB, review the latest measurements of the CIB and its structure, and discuss their implications for detecting and/or constraining the first stars and their epochs.

  13. Cosmic ultraviolet background radiation and zodiacal light

    NASA Technical Reports Server (NTRS)

    Tennyson, P. D.; Henry, R. C.; Feldman, P. D.; Hartig, G. F.

    1988-01-01

    Spectroscopic measurements of the diffuse cosmic UV background in the 1700-2850-A range are presented. In agreement with previous results, the data have resulted in the detection at high Galactic latitude of an intensity of 300 + or - 100 photons/sq cm s sr A at 1800 A without correction for starlight or airglow, a similar intensity over the 1900-2500-A range after correction for measured airglow, and a similar intensity over the 2500-2800-A range after correction for zodiacal light. It is suggested that this radiation may originate partly in line radiation from a Galactic halo and partly from extragalactic sources, perhaps the integrated light of distant galaxies.

  14. Anisotropies in the cosmic microwave background: Theory

    SciTech Connect

    Dodelson, S.

    1998-02-01

    Anisotropies in the Cosmic Microwave Background (CMB) contain a wealth of information about the past history of the universe and the present values of cosmological parameters. I online some of the theoretical advances of the last few years. In particular, I emphasize that for a wide class of cosmological models, theorists can accurately calculate the spectrum to better than a percent. The spectrum of anisotropies today is directly related to the pattern of inhomogeneities present at the time of recombination. This recognition leads to a powerful argument that will enable us to distinguish inflationary models from other models of structure formation. If the inflationary models turn out to be correct, the free parameters in these models will be determined to unprecedented accuracy by the upcoming satellite missions.

  15. A COSMIC MICROWAVE BACKGROUND LENSING MASS MAP AND ITS CORRELATION WITH THE COSMIC INFRARED BACKGROUND

    SciTech Connect

    Holder, G. P.; De Haan, T.; Dobbs, M. A.; Dudley, J.; Viero, M. P.; Bock, J.; Zahn, O.; Aird, K. A.; Benson, B. A.; Bhattacharya, S.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Brodwin, M.; Cho, H-M.; Conley, A.; George, E. M.; Halverson, N. W.; and others

    2013-07-01

    We use a temperature map of the cosmic microwave background (CMB) obtained using the South Pole Telescope at 150 GHz to construct a map of the gravitational convergence to z {approx} 1100, revealing the fluctuations in the projected mass density. This map shows individual features that are significant at the {approx}4{sigma} level, providing the first image of CMB lensing convergence. We cross-correlate this map with Herschel/SPIRE maps covering 90 deg{sup 2} at wavelengths of 500, 350, and 250 {mu}m. We show that these submillimeter (submm) wavelength maps are strongly correlated with the lensing convergence map, with detection significances in each of the three submm bands ranging from 6.7{sigma} to 8.8{sigma}. We fit the measurement of the cross power spectrum assuming a simple constant bias model and infer bias factors of b = 1.3-1.8, with a statistical uncertainty of 15%, depending on the assumed model for the redshift distribution of the dusty galaxies that are contributing to the Herschel/SPIRE maps.

  16. International Cooperation of the Cosmic Infrared Background Experiment

    NASA Astrophysics Data System (ADS)

    Lee, D.-H.; Nam, U.-W.; Lee, S.; Jin, H.; Yuk, I.-S.; Kim, K.-H.; Pak, S.

    2006-12-01

    A Korean team (Korea Astronomy and Space Science Institute, Korea Basic Science Institute, and Kyung Hee University) takes part in an international cooperation project called CIBER (Cosmic Infrared Background ExpeRiment), which has begun with Jet Propulsion Laboratory (JPL) in USA and Institute of Space and Astronautical Science (ISAS) in Japan. CIBER is a rocket-borne instrument, of which the scientific goal is to measure the cosmic near-infrared extra-galactic background to search for signatures of primordial galaxy formation. CIBER consists of a wide-field two-color camera, a low-resolution absolute spectrometer, and a high-resolution narrow-band imaging spectrometer. The Korean team is in charge of the ground support electronics and manufacturing of optical parts of the narrow-band spectrometer, which will provide excellent opportunities for science and technology to Korean infrared groups.

  17. Ultraviolet background radiation from cosmic structure formation

    NASA Astrophysics Data System (ADS)

    Miniati, Francesco; Ferrara, Andrea; White, Simon D. M.; Bianchi, Simone

    2004-03-01

    We calculate the contribution to the ultraviolet background (UVB) from thermal emission from gas shock heated during cosmic structure formation. Our main calculation is based on an updated version of Press-Schechter theory. It is consistent with a more empirical estimate based on the observed properties of galaxies and the observed cosmic star formation history. Thermal UVB emission is characterized by a hard spectrum extending well beyond 4 Ryd. The bulk of the radiation is produced by objects in the mass range 1011-1013 Msolar, i.e. large galaxies and small groups. We compute a composite UVB spectrum due to quasi-stellar object (QSO), stellar and thermal components. The ratio of the UVB intensities at the H and He Lyman limits increases from 60 at z= 2 to more than 300 at z= 6. A comparison of the resulting photoionization rates to the observed Gunn-Peterson effect at high redshifts constrains the escape fraction of ionizing photons from galaxies to be less than a few per cent. Near 1 Ryd, thermal and stellar emission are comparable, amounting to about 10, 20 and 35 per cent of the total flux at redshifts of 3, 4.5 and higher, respectively. However, near the ionization threshold for He II, the thermal contribution is much stronger. It is comparable to the QSO intensity already at redshift ~3 and dominates at redshifts above 4. Thermal photons alone are enough to produce and sustain He II reionization already at z~ 6. We discuss the possible implications of our results for the thermal history of the intergalactic medium, in particular for He II reionization.

  18. GALAXY COUNTS ON THE COSMIC MICROWAVE BACKGROUND COLD SPOT

    SciTech Connect

    Granett, Benjamin R.; Szapudi, Istvan; Neyrinck, Mark C.

    2010-05-01

    The cold spot on the cosmic microwave background (CMB) could arise due to a supervoid at low redshift through the integrated Sachs-Wolfe effect. We imaged the region with MegaCam on the Canada-France-Hawaii Telescope and present galaxy counts in photometric redshift bins. We rule out the existence of a 100 Mpc radius spherical supervoid with underdensity {delta} = -0.3 at 0.5 < z < 0.9 at high significance. The data are consistent with an underdensity at low redshift, but the fluctuations are within the range of cosmic variance and the low-density areas are not contiguous on the sky. Thus, we find no strong evidence for a supervoid. We cannot resolve voids smaller than a 50 Mpc radius; however, these can only make a minor contribution to the CMB temperature decrement.

  19. Cosmic microwave background acoustic peak locations

    NASA Astrophysics Data System (ADS)

    Pan, Z.; Knox, L.; Mulroe, B.; Narimani, A.

    2016-07-01

    The Planck collaboration has measured the temperature and polarization of the cosmic microwave background well enough to determine the locations of eight peaks in the temperature (TT) power spectrum, five peaks in the polarization (EE) power spectrum and 12 extrema in the cross (TE) power spectrum. The relative locations of these extrema give a striking, and beautiful, demonstration of what we expect from acoustic oscillations in the plasma; e.g. that EE peaks fall half way between TT peaks. We expect this because the temperature map is predominantly sourced by temperature variations in the last scattering surface, while the polarization map is predominantly sourced by gradients in the velocity field, and the harmonic oscillations have temperature and velocity 90 deg out of phase. However, there are large differences in expectations for extrema locations from simple analytic models versus numerical calculations. Here, we quantitatively explore the origin of these differences in gravitational potential transients, neutrino free-streaming, the breakdown of tight coupling, the shape of the primordial power spectrum, details of the geometric projection from three to two dimensions, and the thickness of the last scattering surface. We also compare the peak locations determined from Planck measurements to expectations under the Λ cold dark matter model. Taking into account how the peak locations were determined, we find them to be in agreement.

  20. Spatial Statistics of Cosmic Microwave Background Maps

    NASA Astrophysics Data System (ADS)

    Szapudi, I.

    2007-11-01

    Spatial statistics in the Cosmic Microwave Background (CMB) maps are characterized by N-point correlation functions and their corresponding poly-spectra. I focus on basic statistical properties (noise, bias, optimality), and computational issues regarding two- and three-point functions, or angular power spectrum and bi-spectrum. Optimal estimators scale as D^3 for even the two-point statistics, where D is the number of data elements Even naive estimators scale scale D^N for N-point functions. I show that these daunting computational challenges can be met for present and future megapixel CMB maps with considerations about symmetries, multi-resolution techniques, and Monte Carlo methods and careful balancing of optimality, and resolution against computational resources. Once estimated, the interpretation of higher order correlation functions presents unique difficulties due to the large number of configurations: e.g., χ^2 fitting of parameters becomes non-trivial because of the large size of the corresponding covariance matrices. I show that False Discovery Rate based methods can be used for massive hypothesis testing, and I present techniques which help diagnosing and inverting covariance matrices obtained from Monte Carlo simulations.

  1. Probing Inflation via Cosmic Microwave Background Polarimetry

    NASA Technical Reports Server (NTRS)

    Chuss, David T.

    2008-01-01

    The Cosmic Microwave Background (CMB) has been a rich source of information about the early Universe. Detailed measurements of its spectrum and spatial distribution have helped solidify the Standard Model of Cosmology. However, many questions still remain. Standard Cosmology does not explain why the early Universe is geometrically flat, expanding, homogenous across the horizon, and riddled with a small anisotropy that provides the seed for structure formation. Inflation has been proposed as a mechanism that naturally solves these problems. In addition to solving these problems, inflation is expected to produce a spectrum of gravitational waves that will create a particular polarization pattern on the CMB. Detection of this polarized signal is a key test of inflation and will give a direct measurement of the energy scale at which inflation takes place. This polarized signature of inflation is expected to be -9 orders of magnitude below the 2.7 K monopole level of the CMB. This measurement will require good control of systematic errors, an array of many detectors having the requisite sensitivity, and a reliable method for removing polarized foregrounds, and nearly complete sky coverage. Ultimately, this measurement is likely to require a space mission. To this effect, technology and mission concept development are currently underway.

  2. Information gains from cosmic microwave background experiments

    NASA Astrophysics Data System (ADS)

    Seehars, Sebastian; Amara, Adam; Refregier, Alexandre; Paranjape, Aseem; Akeret, Joël

    2014-07-01

    To shed light on the fundamental problems posed by dark energy and dark matter, a large number of experiments have been performed and combined to constrain cosmological models. We propose a novel way of quantifying the information gained by updates on the parameter constraints from a series of experiments which can either complement earlier measurements or replace them. For this purpose, we use the Kullback-Leibler divergence or relative entropy from information theory to measure differences in the posterior distributions in model parameter space from a pair of experiments. We apply this formalism to a historical series of cosmic microwave background experiments ranging from Boomerang to WMAP, SPT, and Planck. Considering different combinations of these experiments, we thus estimate the information gain in units of bits and distinguish contributions from the reduction of statistical errors and the "surprise" corresponding to a significant shift of the parameters' central values. For this experiment series, we find individual relative entropy gains ranging from about 1 to 30 bits. In some cases, e.g. when comparing WMAP and Planck results, we find that the gains are dominated by the surprise rather than by improvements in statistical precision. We discuss how this technique provides a useful tool for both quantifying the constraining power of data from cosmological probes and detecting the tensions between experiments.

  3. Primordial helium and the cosmic background radiation

    SciTech Connect

    Steigman, Gary

    2010-04-01

    The products of primordial nucleosynthesis, along with the cosmic microwave background (CMB) photons, are relics from the early evolution of the Universe whose observations probe the standard model of cosmology and provide windows on new physics beyond the standard models of cosmology and of particle physics. According to the standard, hot big bang cosmology, long before any stars have formed a significant fraction ( ∼ 25%) of the baryonic mass in the Universe should be in the form of helium-4 nuclei. Since current observations of {sup 4}He are restricted to low redshift regions where stellar nucleosynthesis has occurred, an observation of high redshift, prestellar, truly primordial {sup 4}He would constitute a fundamental test of the hot, big bang cosmology. At recombination, long after big bang nucleosynthesis (BBN) has ended, the temperature anisotropy spectrum imprinted on the CMB depends on the {sup 4}He abundance through its connection to the electron density and the effect of the electron density on Silk damping. Since the relic abundance of {sup 4}He is relatively insensitive to the universal density of baryons, but is sensitive to a non-standard, early Universe expansion rate, the primordial mass fraction of {sup 4}He, Yp, offers a test of the consistency of the standard models of BBN and the CMB and, provides constraints on non-standard physics. Here, the WMAP seven year data (supplemented by other CMB experiments), which lead to an indirect determination of Yp at high redshift, are compared to the BBN predictions and to the independent, direct observations of {sup 4}He in low redshift, extragalactic HII regions. At present, given the very large uncertainties in the CMB-determined primordial {sup 4}He abundance (as well as for the helium abundances inferred from HII region observations), any differences between the BBN predictions and the CMB observations are small, at a level ∼<1.5σ.

  4. Spectral measurements of the cosmic microwave background

    SciTech Connect

    Kogut, A.J.

    1989-04-01

    Three experiments have measured the intensity of the Cosmic Microwave Background (CMB) at wavelengths 4.0, 3.0, and 0.21 cm. The measurement at 4.0 cm used a direct-gain total-power radiometer to measure the difference in power between the zenith sky and a large cryogenic reference target. Foreground signals are measured with the same instrument and subtracted from the zenith signal, leaving the CMB as the residual. The reference target consists of a large open-mouth cryostat with a microwave absorber submerged in liquid helium; thin windows block the radiative heat load and prevent condensation atmospheric gases within the cryostat. The thermodynamic temperature of the CMB at 4.0 cm is 2.59 +- 0.07 K. The measurement at 3.0 cm used a superheterodyne Dicke-switched radiometer with a similar reference target to measure the zenith sky temperature. A rotating mirror allowed one of the antenna beams to be redirected to a series of zenith angles, permitting automated atmospheric measurements without moving the radiometer. A weighted average of 5 years of data provided the thermodynamic temperature of the CMB at 3.0 cm of 2.62 +- 0.06 K. The measurement at 0.21 cm used Very Large Array observations of interstellar ortho-formaldehyde to determine the CMB intensity in molecular clouds toward the giant HII region W51A (G49.5-0.4). Solutions of the radiative transfer problem in the context of a large velocity gradient model provided estimates of the CMB temperature within the foreground clouds. Collisional excitation from neutral hydrogen molecules within the clouds limited the precision of the result. The thermodynamic temperature of the CMB at 0.21 cm is 3.2 +- 0.9 K. 72 refs., 27 figs., 38 tabs.

  5. BLAST: RESOLVING THE COSMIC SUBMILLIMETER BACKGROUND

    SciTech Connect

    Marsden, Gaelen; Chapin, Edward L.; Halpern, Mark; Ngo, Henry; Ade, Peter A. R.; Griffin, Matthew; Hargrave, Peter C.; Mauskopf, Philip; Moncelsi, Lorenzo; Pascale, Enzo; Bock, James J.; Devlin, Mark J.; Dicker, Simon R.; Klein, Jeff; Gundersen, Joshua O.; Hughes, David H.; Magnelli, Benjamin; Olmi, Luca; Patanchon, Guillaume

    2009-12-20

    The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) has made 1 deg{sup 2}, deep, confusion-limited maps at three different bands, centered on the Great Observatories Origins Deep Survey South Field. By calculating the covariance of these maps with catalogs of 24 mum sources from the Far-Infrared Deep Extragalactic Legacy Survey, we have determined that the total submillimeter intensities are 8.60 +- 0.59, 4.93 +- 0.34, and 2.27 +- 0.20 nW m{sup -2} sr{sup -1} at 250, 350, and 500 mum, respectively. These numbers are more precise than previous estimates of the cosmic infrared background (CIB) and are consistent with 24 mum-selected galaxies generating the full intensity of the CIB. We find that the fraction of the CIB that originates from sources at z >= 1.2 increases with wavelength, with 60% from high-redshift sources at 500 mum. At all BLAST wavelengths, the relative intensity of high-z sources is higher for 24 mum-faint sources than that for 24 mum-bright sources. Galaxies identified as active galactic nuclei (AGNs) by their Infrared Array Camera colors are 1.6-2.6 times brighter than the average population at 250-500 mum, consistent with what is found for X-ray-selected AGNs. BzK-selected galaxies are found to be moderately brighter than typical 24 mum-selected galaxies in the BLAST bands. These data provide high-precision constraints for models of the evolution of the number density and intensity of star-forming galaxies at high redshift.

  6. Cosmic Infrared Background and Early Galaxy Evolution

    NASA Technical Reports Server (NTRS)

    Kashlinsky, Alexander

    2005-01-01

    The cosmic infrared background (CIB) reflects the sum total of galactic luminosities integrated over the entire age of the universe. From its measurement the red-shifted starlight and dust-absorbed and re-radiated starlight of the CIB can be used to determine (or constrain) the rates of star formation and metal production as a function of time and deduce information about objects at epochs currently inaccessible to telescopic studies. This review discusses the state of current CIB measurements and the (mostly space-based) instruments with which these measurements have been made, the obstacles (the various foreground emissions) and the physics behind the CIB and its structure. Theoretical discussion of the CIB levels can now be normalized to the standard cosmological model narrowing down theoretical uncertainties. We review the information behind and theoretical modeling of both the mean (isotropic) levels of the CIB and their fluctuations. The CIB is divided into three broad bands: near-IR (NIR), mid-IR (MIR) and far-IR (FIR). For each of the bands we review the main contributors to the CIB flux and the epochs at which the bulk of the flux originates. We also discuss the data on the various quantities relevant for correct interpretation of the CIB levels: the star-formation history, the present-day luminosity function measurements, resolving the various galaxy contributors to the CIB, etc. The integrated light of all galaxies in the deepest NIR galaxy counts to date fails to match the observed mean level of the CIB, probably indicating a significant high-redshift contribution to the CIB. Additionally, Population III stars should have left a strong and measurable signature via their contribution to the CIB anisotropies for a wide range of their formation scenarios, and measuring the excess CIB anisotropies coming from high z would provide direct information on the epoch of the first stars.

  7. A preliminary measurement of the cosmic microwave background spectrum by the Cosmic Background Explorer (COBE) satellite

    NASA Technical Reports Server (NTRS)

    Mather, J. C.; Cheng, E. S.; Shafer, R. A.; Bennett, C. L.; Boggess, N. W.; Dwek, E.; Hauser, M. G.; Kelsall, T.; Moseley, S. H., Jr.; Silverberg, R. F.

    1990-01-01

    A preliminary spectrum is presented of the background radiation between 1 and 20/cm from regions near the north Galactic pole, as observed by the FIRAS instrument on the COBE satellite. The spectral resolution is 1/cm. The spectrum is well fitted by a blackbody with a temperature of 2.735 + or - 0.06 K, and the deviation from a blackbody is less than 1 percent of the peak intensity over the range 1-20/cm. These new data show no evidence for the submillimeter excess previously reported by Matsumoto et al. (1988) in the cosmic microwave background. Further analysis and additional data are expected to improve the sensitivity to deviations from a blackbody spectrum by an order of magnitude.

  8. Origin of the high energy cosmic neutrino background.

    PubMed

    Dado, Shlomo; Dar, Arnon

    2014-11-01

    The diffuse background of very high energy extraterrestrial neutrinos recently discovered with IceCube is compatible with that expected from cosmic ray interactions in the Galactic interstellar medium plus that expected from hadronic interactions near the source and in the intergalactic medium of the cosmic rays which have been accelerated by the jets that produce gamma ray bursts. PMID:25415894

  9. Scientific results from the Cosmic Background Explorer (COBE)

    PubMed Central

    Bennett, C. L.; Boggess, N. W.; Cheng, E. S.; Hauser, M. G.; Kelsall, T.; Mather, J. C.; Moseley, S. H.; Murdock, T. L.; Shafer, R. A.; Silverberg, R. F.; Smoot, G. F.; Weiss, R.; Wright, E. L.

    1993-01-01

    The National Aeronautics and Space Administration (NASA) has flown the COBE satellite to observe the Big Bang and the subsequent formation of galaxies and large-scale structure. Data from the Far-Infrared Absolute Spectrophotometer (FIRAS) show that the spectrum of the cosmic microwave background is that of a black body of temperature T = 2.73 ± 0.06 K, with no deviation from a black-body spectrum greater than 0.25% of the peak brightness. The data from the Differential Microwave Radiometers (DMR) show statistically significant cosmic microwave background anisotropy, consistent with a scale-invariant primordial density fluctuation spectrum. Measurements from the Diffuse Infrared Background Experiment (DIRBE) provide new conservative upper limits to the cosmic infrared background. Extensive modeling of solar system and galactic infrared foregrounds is required for further improvement in the cosmic infrared background limits. PMID:11607383

  10. Microwave and theoretical studies for Cosmic Background Explorer satellite

    NASA Technical Reports Server (NTRS)

    Wilkinson, D. T.

    1983-01-01

    The Cosmic Background Explorer (COBE) satellite, its instruments, and its scientific mission are discussed. The COBE radiometer is considered, and measurement of galactic radio emission with masers is reviewed. Extragalactic radiation and zodiacal dust are mentioned briefly.

  11. Search for Cosmic Strings in Cosmic Microwave BackgroundAnisotropies

    SciTech Connect

    Jeong, E.; Smoot, GF

    2004-06-01

    We have searched the 1st-year WMAP W-Band CMB anisotropy map for evidence of cosmic strings. We have set a limit of delta = 8 pi G mu/ c2 < 8.2 times 10-6 at 95 percent CL for statistical search for a significant number of strings in the map. We also have set a limit using the uniform distribution of strings model in the WMAP data with delta = 8pi G mu/c2 < 7.34 times 10-5 at 95 percent CL. And the pattern search technique we developed here set a limit delta = 8 pi G mu/c2 < 1.54 times 10-5 at 95 percent CL.

  12. Gravitational-wave stochastic background from cosmic strings.

    PubMed

    Siemens, Xavier; Mandic, Vuk; Creighton, Jolien

    2007-03-16

    We consider the stochastic background of gravitational waves produced by a network of cosmic strings and assess their accessibility to current and planned gravitational wave detectors, as well as to big bang nucleosynthesis (BBN), cosmic microwave background (CMB), and pulsar timing constraints. We find that current data from interferometric gravitational wave detectors, such as Laser Interferometer Gravitational Wave Observatory (LIGO), are sensitive to areas of parameter space of cosmic string models complementary to those accessible to pulsar, BBN, and CMB bounds. Future more sensitive LIGO runs and interferometers such as Advanced LIGO and Laser Interferometer Space Antenna (LISA) will be able to explore substantial parts of the parameter space. PMID:17501038

  13. Intergalactic shock acceleration and the cosmic gamma-ray background

    NASA Astrophysics Data System (ADS)

    Miniati, Francesco

    2002-11-01

    We investigate numerically the contribution to the cosmic gamma-ray background from cosmic-ray ions and electrons accelerated at intergalactic shocks associated with cosmological structure formation. We show that the kinetic energy of accretion flows in the low-redshift intergalactic medium is thermalized primarily through moderately strong shocks, which allow for an efficient conversion of shock ram pressure into cosmic-ray pressure. Cosmic rays accelerated at these shocks produce a diffuse gamma-ray flux which is dominated by inverse Compton emission from electrons scattering off cosmic microwave background photons. Decay of neutral π mesons generated in p-p inelastic collisions of the ionic cosmic-ray component with the thermal gas contribute about 30 per cent of the computed emission. Based on experimental upper limits on the photon flux above 100 MeV from nearby clusters we constrain the efficiency of conversion of shock ram pressure into relativistic CR electrons to <~1 per cent. Thus, we find that cosmic rays of cosmological origin can generate an overall significant fraction of order 20 per cent and no more than 30 per cent of the measured gamma-ray background.

  14. D-term inflation, cosmic strings, and consistency with cosmic microwave background measurements.

    PubMed

    Rocher, Jonathan; Sakellariadou, Mairi

    2005-01-14

    Standard D-term inflation is studied in the framework of supergravity. D-term inflation produces cosmic strings; however, it can still be compatible with cosmic microwave background (CMB) measurements without invoking any new physics. The cosmic strings contribution to the CMB data is not constant, nor dominant, contrary to some previous results. Using current CMB measurements, the free parameters (gauge and superpotential couplings, as well as the Fayet-Iliopoulos term) of D-term inflation are constrained. PMID:15698061

  15. Search for the Cosmic Infrared Background Radiation using COBE Data

    NASA Technical Reports Server (NTRS)

    Hauser, Michael

    2001-01-01

    This project was initiated to allow completion of the primary investigation of the Diffuse Infrared Background Experiment (DIRBE) on NASA's Cosmic Background Explorer (CORE) mission, and to study the implications of those findings. The Principal Investigator (PI) on this grant was also the Principal Investigator on the DIRBE team. The project had two specific goals: Goal 1: Seek improved limits upon, or detections of, the cosmic infrared background radiation using data from the COBE Diffuse Infrared Background Experiment (DIRBE). Goal 2: Explore the implications of the limits and measured values of the cosmic infrared background for energy releases in the Universe since the formation of the first luminous sources. Both of these goals have been successfully accomplished.

  16. From Cosmic Microwave Background to Cosmic Infrared Background: dusty star-formation in the making

    NASA Astrophysics Data System (ADS)

    Lagache, Guilaine

    2015-08-01

    How the clumpy structured universe that we see today evolved from the smoothly distributed matter that existed during the dark ages is one of the most pressing questions of modern Cosmology. In the last few years, it has become clear that dusty star-forming galaxies are participating to this major change. Indeed they are a critical player in the assembly of stellar mass and the evolution of massive galaxies.Dusty star-forming galaxies at high redshift are very difficult to detect individually because they are so faint and numerous (compared to the angular resolution achievable in the far-IR to mm), that confusion plagues observations substantially. As a result, CMB experiments, such as Planck, can only see the brightest objects that represent the tip of the iceberg in terms of galaxy mass halos and star formation rates. But fortunately, those experiments are sensitive enough to measure the cumulative IR emission from all galaxies throughout cosmic history, the cosmic IR background. The anisotropies detected in this background trace the large-scale distribution of star-forming galaxies and, to some extent, the underlying distribution of the dark matter haloes in which galaxies reside. It is so bright that it represents (together with the shot noise) the main foreground contaminant to CMB temperature maps at small scales.I will review the current measurements of CIB anisotropies in Planck, but also in SPT, ACT and Herschel. I will discussed what we've learned from these measurements in the framework of galaxy evolution. I will show that most of the information from CIB anisotropies alone has been extracted; the future is now in cross-correlation. Because dusty galaxies trace the underlying dark matter, the CIB will correlate with any other tracer of the same dark matter field, provided that both overlap in redshift. The potential of Planck maps, covering the whole sky, is tremendous. A good illustration of this promising future is the fact that the Planck discovered

  17. The cosmic X-ray background

    NASA Technical Reports Server (NTRS)

    Boldt, Elihu A.

    1987-01-01

    The present knowledge about the overall spectrum of the isotropic extragalactic background of electromagnetic radiation is summarized. The role of the HEAO program is discussed. Spectral measurements from HEAO are examined.

  18. A New Measurement of the Cosmic X-ray Background

    SciTech Connect

    Moretti, A.

    2009-05-11

    I present a new analytical description of the cosmic X-ray background (CXRB) spectrum in the 1.5-200 keV energy band, obtained by combining the new measurement performed by the Swift X-ray telescope (XRT) with the recently published Swift burst alert telescope (BAT) measurement. A study of the cosmic variance in the XRT band (1.5-7 keV) is also presented. I find that the expected cosmic variance (expected from LogN-LogS) scales as {omega}{sup -0.3}(where {omega} is the surveyed area) in very good agreement with XRT data.

  19. Patterns of the cosmic microwave background from evolving string networks

    NASA Technical Reports Server (NTRS)

    Bouchet, Francois R.; Bennett, David P.; Stebbins, Albert

    1988-01-01

    A network of cosmic strings generated in the early universe may still exist today. As the strings move across the sky, they produce, by gravitational lensing, a characteristic pattern of anisotropies in the temperature of the cosmic microwave background. The observed absence of such anisotropies places constraints on theories in which galaxy formation is seeded by strings, but it is anticipated that the next generation of experiments will detect them.

  20. Radio brightness distribution within cosmic background fluctuations

    NASA Astrophysics Data System (ADS)

    Sazhin, M. V.

    1985-08-01

    The angular fluctuations delta T in the microwave background temperature constitute a random process. Calculations are performed for the number of 'pips' above a base level that might be produced by primordial scalar density perturbations or gravitational waves. The flux density expected for typical pips is determined, as well as the mean solid angle subtended by a pip that would exceed a level three times the dispersion in delta T.

  1. Cosmic Infrared Background Fluctuations and Zodiacal Light

    NASA Astrophysics Data System (ADS)

    Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

    2016-06-01

    We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS field at low ecliptic latitude where the zodiacal light intensity varies by factors of ˜2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (≳100″) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

  2. Pregalactic dust and distortions of the cosmic-background spectrum

    NASA Astrophysics Data System (ADS)

    Aiello, S.; Melchiorri, F.; Cecchini, S.; Mandolesi, N.

    1980-04-01

    The paper focuses on a comparison between the cosmic-background spectrum and the emission by a dust cloud of silicate grains. The similarity between the emission from a cloud of silicate grains and the observed cosmic-background spectrum is clearly shown schematically. However, for a quantitative comparison a more detailed computation is required. An expression is written for the observed cosmic-background spectrum in terms of the deceleration parameter, the grain extinction cross section, the number density of grains at the present epoch, and the rate of grain production in the pregalactic epoch /f(z)/. A complete analysis of the problem requires the computation of the optical depth for different values of f(z), for different grain materials, and for various distributions of grain radii. All these computations are reported by Aiello et al. (1979). The paper presents only preliminary results.

  3. The Cosmic Microwave Background & Inflation, Then & Now

    NASA Astrophysics Data System (ADS)

    Bond, J. Richard; Contaldi, Carlo; Pogosyan, Dmitry; Mason, Brian; Myers, Steve; Pearson, Tim; Pen, Ue-Li; Prunet, Simon; Readhead, Tony; Sievers, Jonathan

    2002-12-01

    % level. A broad-band DASI detection consistent with inflation models was just reported. A 7th pillar, anisotropies induced by gravity wave quantum noise, could be too small to detect. A minimal inflation parameter set, {ωb, ωcdm, Ωtot, ΩQ, wQ, ns, τC, σ8}, is used to illustrate the power of the current data. After marginalizing over the other cosmic and experimental variables, we find the current CMB+LSS+SN1 data give Ωtot = 1.00-.03+.07, consistent with (non-baroque) inflation theory. Restricting to Ωtot = 1, we find a nearly scale invariant spectrum, ns = 0.97-.05+.06. The CDM density, ωcdm = Ωcdmh2 = .12-.01+.01, and baryon density, ωb ≡ Ωbh2 = .022-.002+.003, are in the expected range. (The Big Bang nucleosynthesis estimate is 0.019 +/- 0.002.) Substantial dark (unclustered) energy is inferred, ΩQ ~ 0.68 +/- 0.05, and CMB+LSS ΩQ values are compatible with the independent SN1 estimates. The dark energy equation of state, crudely parameterized by a quintessence-field pressure-to-density ratio wQ, is not well determined by CMB+LSS (wQ < -0.4 at 95% CL), but when combined with SN1 the resulting wQ < -0.7 limit is quite consistent with the wQ=-1 cosmological constant case.

  4. Correlation between galactic HI and the cosmic microwave background

    SciTech Connect

    Land, Kate; Slosar, Anze

    2007-10-15

    We revisit the issue of a correlation between the atomic hydrogen gas in our local galaxy and the cosmic microwave background, a detection of which has been claimed in some literature. We cross correlate the 21-cm emission of galactic atomic hydrogen as traced by the Leiden/Argentine/Bonn Galactic Hi survey with the 3-year cosmic microwave background data from the Wilkinson microwave anisotropy probe. We consider a number of angular scales, masks, and Hi velocity slices and find no statistically significant correlation.

  5. Stage 4 Cosmic Microwave Background Experiment

    NASA Astrophysics Data System (ADS)

    Carlstrom, John

    2016-03-01

    Measurements of the CMB have driven our understanding of the universe and the physics that govern its evolution from quantum fluctuations to its present state. They provide the foundation for the remarkable 6-parameter cosmological model, ΛCDM, which fits all cosmological data, although there are some tensions which may hint at new physics, or simply unaccounted systematics. Far from being the last word in cosmology, the model raises deep questions: Is Inflation correct? What is its energy scale? What is the dark matter? What is the nature of dark energy? There is still a lot to learn from the CMB measurements. We are searching for the unique B-mode polarization that would be induced on the CMB by inflationary gravitational waves. We are able to detect the impact of the neutrino background on the CMB, which can be used to provide precise constraints on the number and masses of the neutrinos. We are untangling the correlations in the CMB induced by gravitational lensing to make maps of all the mass in the universe. We are measuring the scattering of the CMB by ionized structures, the Sunyaev-Zel'dovich effects, to detect clusters of galaxies and soon to map the momentum of the universe in addition to its density. To realize the enormous potential of these CMB tools we need to greatly increase the sensitivity of CMB measurements. We can expect significant advances in the next few years as the ongoing experiments deploy of order 10,000 detectors (Stage III), but to achieve critical threshold crossing goals we need to go further. The CMB community is therefore planning CMB-S4, an ambitious next generation (Stage IV) ground-based program with order of 500,000 detectors with science goals that include detecting or ruling out large field inflationary models, determining the number and masses of the neutrinos, providing precision constraints on dark energy through its impact on structure formation, as well as searching for cracks in the ΛCDM model.

  6. The cosmic microwave background - A probe of particle physics

    NASA Technical Reports Server (NTRS)

    Silk, Joseph

    1990-01-01

    The current status of spectral distortions and angular anisotropies in the cosmic microwave background is reviewed, with emphasis on the role played by weakly interacting particle dark matter. Theoretical predictions and recent observational results are described, and prospects for future progress are summarized.

  7. Spectral distortions and anisotropies of the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    De Zotti, Gianfranco; Negrello, Mattia

    2015-12-01

    This contribution presents a synthetic review of the theory and the observations on spectral distortions and on anisotropies of the Cosmic Microwave Background (CMB). For a better understanding of the content of these lectures, it is useful to refer also to the figures contained in the slides available on the School's website.

  8. Real-Time Active Cosmic Neutron Background Reduction Methods

    SciTech Connect

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Mitchell, Stephen; Guss, Paul

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray-induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory–Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the low-energy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 μs) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of man-made neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux

  9. Real-time active cosmic neutron background reduction methods

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Mitchell, Stephen; Guss, Paul

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray‒induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory-Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the lowenergy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 μs) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of manmade neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux

  10. Distortions of the cosmic microwave background spectrum by dust

    NASA Technical Reports Server (NTRS)

    Rowan-Robinson, M.; Negroponte, J.; Silk, J.

    1979-01-01

    The effects of dust in the early universe on the spectrum of the cosmic microwave background are considered, taking into account the effects of a pregalactic generation of stars. It is shown that observed distortions of the background spectrum from that of a black body at 3 K could be due to emission by silicate dust grains at a metal abundance of 0.00001 by mass and with a substantial energy input, which represent the remnants of population III stars. Attempts to fit the microwave background spectrum to the model of Rees (1978) in which the entire cosmic background is accounted for by grain emission are shown to require an implausible value for the metal abundance at early epochs, and not to agree with the millimeter and submillimeter spectrum observed by Woody and Richards (1979).

  11. Distortion of the cosmic background radiation by superconducting strings

    NASA Technical Reports Server (NTRS)

    Ostriker, J. P.; Thompson, C.

    1987-01-01

    Superconducting cosmic strings can be significant energy sources, keeping the universe ionized past the commonly assumed epoch of recombination. As a result, the spectrum of the cosmic background radiation is distorted in the presence of heated primordial gas via the Suniaev-Zel'dovich effect. Thiis distortion can be relatively large: the Compton y parameter attains a maximum in the range 0.001-0.005, with these values depending on the mass scale of the string. A significant contribution to y comes from loops decaying at high redshift when the universe is optically thick to Thomson scattering. Moreover, the isotropic spectral distortion is large compared to fluctuations at all angular scales.

  12. How to fool cosmic microwave background parameter estimation

    SciTech Connect

    Kinney, William H.

    2001-02-15

    With the release of the data from the Boomerang and MAXIMA-1 balloon flights, estimates of cosmological parameters based on the cosmic microwave background (CMB) have reached unprecedented precision. In this paper I show that it is possible for these estimates to be substantially biased by features in the primordial density power spectrum. I construct primordial power spectra which mimic to within cosmic variance errors the effect of changing parameters such as the baryon density and neutrino mass, meaning that even an ideal measurement would be unable to resolve the degeneracy. Complementary measurements are necessary to resolve this ambiguity in parameter estimation efforts based on CMB temperature fluctuations alone.

  13. GIANT RINGS IN THE COSMIC MICROWAVE BACKGROUND SKY

    SciTech Connect

    Kovetz, Ely D.; Ben-David, Assaf; Itzhaki, Nissan E-mail: bd.assaf@gmail.co

    2010-11-20

    We find a unique direction in the cosmic microwave background sky around which giant rings have an anomalous mean temperature profile. This direction is in very close alignment with the afore measured anomalously large bulk flow direction. Using Monte Carlo simulations, we estimate the significance of the giant rings at the 3{sigma} level and the alignment with the bulk flow at 2.5{sigma}. We argue that a cosmic defect seeded by a pre-inflationary particle could explain the giant rings, the large bulk flow, and their alignment.

  14. Cosmic microwave background polarization signals from tangled magnetic fields.

    PubMed

    Seshadri, T R; Subramanian, K

    2001-09-01

    Tangled, primordial cosmic magnetic fields create small rotational velocity perturbations on the last scattering surface of the cosmic microwave background radiation. For fields which redshift to a present value of B0 = 3 x 10(-9) G, these vector modes are shown to generate polarization anisotropies of order 0.1-4 microK on small angular scales (500

  15. Assessment of Cosmic Background Attenuation at Building 3425 (Underground Laboratory)

    SciTech Connect

    Kouzes, Richard T.; Borgardt, James D.; Lintereur, Azaree T.; Panisko, Mark E.

    2009-10-01

    Specifications for the Underground Facility (building 3425) in the Radiation Detection and Nuclear Sciences complex presently under construction at Pacific Northwest National Laboratory mandate a 30 meters water equivalent shielding for cosmic background attenuation at the 30-foot underground depth of the laboratory. A set thickness of a specified fill material was determined; however a smaller thickness of a higher density material was used for the earthen bunker. Questions arose as to whether this altered configuration met the required shielding specifications. A series of measurements were made to address this concern using a 4”x4”x16” NaI(Tl) detector (Scionix Holland, 3.5N-E2-X). Cosmic ray data were taken at the surface, and at several locations within the underground facility in order to obtain an experimental value for the attenuation of the cosmic radiation. This experimental result was compared with the contracted attenuation.

  16. AXAF Detector Backgrounds Produced By Cosmic Ray Protons

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, K. L.; Dietz, K. L.; O'Dell, S. L.; Weisskopf, M. C.

    1997-01-01

    One of the science instruments on the Advanced X-ray Astrophysics Facility (AXAF), planned for launch in 1998 into a highly elliptical (10,000 km x 140,000 km) orbit, is a microchannel plate High Resolution Camera (HRC). This detector is designed to provide imaging and spectroscopic observations of x-rays emitted by stellar sources in the 0.1 to 10 keV energy range. Described here are analyses made to determine the expected time-dependent detector background from prompt and delayed (activation) radiation initiated by galactic cosmic-ray (GCR) proton interactions in the spacecraft and payload. Numerical simulations were made using the coupled set of Monte Carlo radiation transport codes, analysis software, and data bases shown. The major codes are HETC for nucleon-meson transport, EGS for simulating electromagnetic cascades, and MORSE for low-energy (less than 15 MeV) neutron transport. The simulation follows the transport history of photons in the energy range from - 100 GeV down to approx. 0.1 keV due to gamma-ray sources from neutral pion decay, high-energy (spallation) collisions, and low-energy neutron inelastic scattering and capture reactions. Also included is radioisotope production and the tracking of gamma-rays, electrons, and positrons from induced radioactivity.

  17. Forecasting constraints from the cosmic microwave background on eternal inflation

    NASA Astrophysics Data System (ADS)

    Feeney, Stephen M.; Elsner, Franz; Johnson, Matthew C.; Peiris, Hiranya V.

    2015-10-01

    We forecast the ability of cosmic microwave background (CMB) temperature and polarization data sets to constrain theories of eternal inflation using cosmic bubble collisions. Using the Fisher matrix formalism, we determine both the overall detectability of bubble collisions and the constraints achievable on the fundamental parameters describing the underlying theory. The CMB signatures considered are based on state-of-the-art numerical relativistic simulations of the bubble collision spacetime, evolved using the full temperature and polarization transfer functions. Comparing a theoretical cosmic-variance-limited experiment to the WMAP and Planck satellites, we find that there is no improvement to be gained from future temperature data, that adding polarization improves detectability by approximately 30%, and that cosmic-variance-limited polarization data offer only marginal improvements over Planck. The fundamental parameter constraints achievable depend on the precise values of the tensor-to-scalar ratio and energy density in (negative) spatial curvature. For a tensor-to-scalar ratio of 0.1 and spatial curvature at the level of 1 0-4, using cosmic-variance-limited data it is possible to measure the width of the potential barrier separating the inflating false vacuum from the true vacuum down to MPl/500 , and the initial proper distance between colliding bubbles to a factor π /2 of the false vacuum horizon size (at three sigma). We conclude that very near-future data will have the final word on bubble collisions in the CMB.

  18. Level crossing analysis of cosmic microwave background radiation: a method for detecting cosmic strings

    SciTech Connect

    Movahed, M. Sadegh; Khosravi, Shahram E-mail: khosravi@ipm.ir

    2011-03-01

    In this paper we study the footprint of cosmic string as the topological defects in the very early universe on the cosmic microwave background radiation. We develop the method of level crossing analysis in the context of the well-known Kaiser-Stebbins phenomenon for exploring the signature of cosmic strings. We simulate a Gaussian map by using the best fit parameter given by WMAP-7 and then superimpose cosmic strings effects on it as an incoherent and active fluctuations. In order to investigate the capability of our method to detect the cosmic strings for the various values of tension, Gμ, a simulated pure Gaussian map is compared with that of including cosmic strings. Based on the level crossing analysis, the superimposed cosmic string with Gμ∼>4 × 10{sup −9} in the simulated map without instrumental noise and the resolution R = 1' could be detected. In the presence of anticipated instrumental noise the lower bound increases just up to Gμ∼>5.8 × 10{sup −9}.

  19. Studying extragalactic background fluctuations with the Cosmic Infrared Background ExpeRiment 2 (CIBER-2)

    NASA Astrophysics Data System (ADS)

    Lanz, Alicia; Arai, Toshiaki; Battle, John; Bock, James; Cooray, Asantha; Hristov, Viktor; Korngut, Phillip; Lee, Dae Hee; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Morford, Tracy; Onishi, Yosuke; Shirahata, Mai; Tsumura, Kohji; Wada, Takehiko; Zemcov, Michael

    2014-08-01

    Fluctuations in the extragalactic background light trace emission from the history of galaxy formation, including the emission from the earliest sources from the epoch of reionization. A number of recent near-infrared measure- ments show excess spatial power at large angular scales inconsistent with models of z < 5 emission from galaxies. These measurements have been interpreted as arising from either redshifted stellar and quasar emission from the epoch of reionization, or the combined intra-halo light from stars thrown out of galaxies during merging activity at lower redshifts. Though astrophysically distinct, both interpretations arise from faint, low surface brightness source populations that are difficult to detect except by statistical approaches using careful observations with suitable instruments. The key to determining the source of these background anisotropies will be wide-field imaging measurements spanning multiple bands from the optical to the near-infrared. The Cosmic Infrared Background ExpeRiment 2 (CIBER-2) will measure spatial anisotropies in the extra- galactic infrared background caused by cosmological structure using six broad spectral bands. The experiment uses three 2048 x 2048 Hawaii-2RG near-infrared arrays in three cameras coupled to a single 28.5 cm telescope housed in a reusable sounding rocket-borne payload. A small portion of each array will also be combined with a linear-variable filter to make absolute measurements of the spectrum of the extragalactic background with high spatial resolution for deep subtraction of Galactic starlight. The large field of view and multiple spectral bands make CIBER-2 unique in its sensitivity to fluctuations predicted by models of lower limits on the luminosity of the first stars and galaxies and in its ability to distinguish between primordial and foreground anisotropies. In this paper the scientific motivation for CIBER-2 and details of its first flight instrumentation will be discussed, including

  20. Cosmic microwave background observables of small field models of inflation

    SciTech Connect

    Ben-Dayan, Ido; Brustein, Ram E-mail: ramyb@bgu.ac.il

    2010-09-01

    We construct a class of single small field models of inflation that can predict, contrary to popular wisdom, an observable gravitational wave signal in the cosmic microwave background anisotropies. The spectral index, its running, the tensor to scalar ratio and the number of e-folds can cover all the parameter space currently allowed by cosmological observations. A unique feature of models in this class is their ability to predict a negative spectral index running in accordance with recent cosmic microwave background observations. We discuss the new class of models from an effective field theory perspective and show that if the dimensionless trilinear coupling is small, as required for consistency, then the observed spectral index running implies a high scale of inflation and hence an observable gravitational wave signal. All the models share a distinct prediction of higher power at smaller scales, making them easy targets for detection.

  1. Cosmic acceleration without dark energy: background tests and thermodynamic analysis

    SciTech Connect

    Lima, J.A.S.; Graef, L.L.; Pavón, D.; Basilakos, Spyros E-mail: leilagraef@usp.br E-mail: svasil@academyofathens.gr

    2014-10-01

    A cosmic scenario with gravitationally induced particle creation is proposed. In this model the Universe evolves from an early to a late time de Sitter era, with the recent accelerating phase driven only by the negative creation pressure associated with the cold dark matter component. The model can be interpreted as an attempt to reduce the so-called cosmic sector (dark matter plus dark energy) and relate the two cosmic accelerating phases (early and late time de Sitter expansions). A detailed thermodynamic analysis including possible quantum corrections is also carried out. For a very wide range of the free parameters, it is found that the model presents the expected behavior of an ordinary macroscopic system in the sense that it approaches thermodynamic equilibrium in the long run (i.e., as it nears the second de Sitter phase). Moreover, an upper bound is found for the Gibbons–Hawking temperature of the primordial de Sitter phase. Finally, when confronted with the recent observational data, the current 'quasi'-de Sitter era, as predicted by the model, is seen to pass very comfortably the cosmic background tests.

  2. Cosmic acceleration without dark energy: background tests and thermodynamic analysis

    NASA Astrophysics Data System (ADS)

    Lima, J. A. S.; Graef, L. L.; Pavón, D.; Basilakos, Spyros

    2014-10-01

    A cosmic scenario with gravitationally induced particle creation is proposed. In this model the Universe evolves from an early to a late time de Sitter era, with the recent accelerating phase driven only by the negative creation pressure associated with the cold dark matter component. The model can be interpreted as an attempt to reduce the so-called cosmic sector (dark matter plus dark energy) and relate the two cosmic accelerating phases (early and late time de Sitter expansions). A detailed thermodynamic analysis including possible quantum corrections is also carried out. For a very wide range of the free parameters, it is found that the model presents the expected behavior of an ordinary macroscopic system in the sense that it approaches thermodynamic equilibrium in the long run (i.e., as it nears the second de Sitter phase). Moreover, an upper bound is found for the Gibbons-Hawking temperature of the primordial de Sitter phase. Finally, when confronted with the recent observational data, the current `quasi'-de Sitter era, as predicted by the model, is seen to pass very comfortably the cosmic background tests.

  3. Consistent cosmic microwave background spectra from quantum depletion

    NASA Astrophysics Data System (ADS)

    Casadio, Roberto; Kühnel, Florian; Orlandi, Alessio

    2015-09-01

    Following a new quantum cosmological model proposed by Dvali and Gomez, we quantitatively investigate possible modifications to the Hubble parameter and following corrections to the cosmic microwave background spectrum. In this model, scalar and tensor perturbations are generated by the quantum depletion of the background inflaton and graviton condensate respectively. We show how the inflaton mass affects the power spectra and the tensor-to-scalar ratio. Masses approaching the Planck scale would lead to strong deviations, while standard spectra are recovered for an inflaton mass much smaller than the Planck mass.

  4. Evidence for gravitational lensing of the cosmic microwave background polarization from cross-correlation with the cosmic infrared background.

    PubMed

    Ade, P A R; Akiba, Y; Anthony, A E; Arnold, K; Atlas, M; Barron, D; Boettger, D; Borrill, J; Borys, C; Chapman, S; Chinone, Y; Dobbs, M; Elleflot, T; Errard, J; Fabbian, G; Feng, C; Flanigan, D; Gilbert, A; Grainger, W; Halverson, N W; Hasegawa, M; Hattori, K; Hazumi, M; Holzapfel, W L; Hori, Y; Howard, J; Hyland, P; Inoue, Y; Jaehnig, G C; Jaffe, A; Keating, B; Kermish, Z; Keskitalo, R; Kisner, T; Le Jeune, M; Lee, A T; Leitch, E M; Linder, E; Lungu, M; Matsuda, F; Matsumura, T; Meng, X; Miller, N J; Morii, H; Moyerman, S; Myers, M J; Navaroli, M; Nishino, H; Paar, H; Peloton, J; Poletti, D; Quealy, E; Rebeiz, G; Reichardt, C L; Richards, P L; Ross, C; Rotermund, K; Schanning, I; Schenck, D E; Sherwin, B D; Shimizu, A; Shimmin, C; Shimon, M; Siritanasak, P; Smecher, G; Spieler, H; Stebor, N; Steinbach, B; Stompor, R; Suzuki, A; Takakura, S; Tikhomirov, A; Tomaru, T; Wilson, B; Yadav, A; Zahn, O

    2014-04-01

    We reconstruct the gravitational lensing convergence signal from cosmic microwave background (CMB) polarization data taken by the Polarbear experiment and cross-correlate it with cosmic infrared background maps from the Herschel satellite. From the cross spectra, we obtain evidence for gravitational lensing of the CMB polarization at a statistical significance of 4.0σ and indication of the presence of a lensing B-mode signal at a significance of 2.3σ. We demonstrate that our results are not biased by instrumental and astrophysical systematic errors by performing null tests, checks with simulated and real data, and analytical calculations. This measurement of polarization lensing, made via the robust cross-correlation channel, not only reinforces POLARBEAR auto-correlation measurements, but also represents one of the early steps towards establishing CMB polarization lensing as a powerful new probe of cosmology and astrophysics. PMID:24745402

  5. Evidence for Gravitational Lensing of the Cosmic Microwave Background Polarization from Cross-Correlation with the Cosmic Infrared Background

    NASA Astrophysics Data System (ADS)

    Ade, P. A. R.; Akiba, Y.; Anthony, A. E.; Arnold, K.; Atlas, M.; Barron, D.; Boettger, D.; Borrill, J.; Borys, C.; Chapman, S.; Chinone, Y.; Dobbs, M.; Elleflot, T.; Errard, J.; Fabbian, G.; Feng, C.; Flanigan, D.; Gilbert, A.; Grainger, W.; Halverson, N. W.; Hasegawa, M.; Hattori, K.; Hazumi, M.; Holzapfel, W. L.; Hori, Y.; Howard, J.; Hyland, P.; Inoue, Y.; Jaehnig, G. C.; Jaffe, A.; Keating, B.; Kermish, Z.; Keskitalo, R.; Kisner, T.; Le Jeune, M.; Lee, A. T.; Leitch, E. M.; Linder, E.; Lungu, M.; Matsuda, F.; Matsumura, T.; Meng, X.; Miller, N. J.; Morii, H.; Moyerman, S.; Myers, M. J.; Navaroli, M.; Nishino, H.; Paar, H.; Peloton, J.; Poletti, D.; Quealy, E.; Rebeiz, G.; Reichardt, C. L.; Richards, P. L.; Ross, C.; Rotermund, K.; Schanning, I.; Schenck, D. E.; Sherwin, B. D.; Shimizu, A.; Shimmin, C.; Shimon, M.; Siritanasak, P.; Smecher, G.; Spieler, H.; Stebor, N.; Steinbach, B.; Stompor, R.; Suzuki, A.; Takakura, S.; Tikhomirov, A.; Tomaru, T.; Wilson, B.; Yadav, A.; Zahn, O.; Polarbear Collaboration

    2014-04-01

    We reconstruct the gravitational lensing convergence signal from cosmic microwave background (CMB) polarization data taken by the Polarbear experiment and cross-correlate it with cosmic infrared background maps from the Herschel satellite. From the cross spectra, we obtain evidence for gravitational lensing of the CMB polarization at a statistical significance of 4.0σ and indication of the presence of a lensing B-mode signal at a significance of 2.3σ. We demonstrate that our results are not biased by instrumental and astrophysical systematic errors by performing null tests, checks with simulated and real data, and analytical calculations. This measurement of polarization lensing, made via the robust cross-correlation channel, not only reinforces POLARBEAR auto-correlation measurements, but also represents one of the early steps towards establishing CMB polarization lensing as a powerful new probe of cosmology and astrophysics.

  6. Dark before light: testing the cosmic expansion history through the cosmic microwave background

    SciTech Connect

    Linder, Eric V.; Smith, Tristan L. E-mail: tlsmith@berkeley.edu

    2011-04-01

    The cosmic expansion history proceeds in broad terms from a radiation dominated epoch to matter domination to an accelerated, dark energy dominated epoch. We investigate whether intermittent periods of acceleration (from a canonical, minimally coupled scalar field) are possible in the early universe — between Big Bang nucleosynthesis (BBN) and recombination and beyond. We establish that the standard picture is remarkably robust: anisotropies in the cosmic microwave background consistent with ΛCDM will exclude any extra period of accelerated expansion between 1 ≤ z∼<10{sup 5} (corresponding to 5 × 10{sup −4}eV ≤ T∼<25eV)

  7. Constraining invisible neutrino decays with the cosmic microwave background

    SciTech Connect

    Hannestad, Steen; Raffelt, Georg G.

    2005-11-15

    Precision measurements of the acoustic peaks of the cosmic microwave background indicate that neutrinos must be freely streaming at the photon decoupling epoch when T{approx_equal}0.3 eV. This requirement implies restrictive limits on 'secret neutrino interactions', notably on neutrino Yukawa couplings with hypothetical low-mass (pseudo)scalars {phi}. For diagonal couplings in the neutrino mass basis we find g < or approx. 1x10{sup -7}, comparable to limits from supernova 1987A. For the off-diagonal couplings and assuming hierarchical neutrino masses we find g < or approx. 1x10{sup -11}(0.05 eV/m){sup 2} where m is the heavier mass of a given neutrino pair connected by g. This stringent limit excludes that the flavor content of high-energy neutrinos from cosmic-ray sources is modified by {nu}{yields}{nu}{sup '}+{phi} decays on their way to Earth.

  8. The cosmic ray antiproton background for AMS-02

    SciTech Connect

    Kappl, Rolf; Winkler, Martin Wolfgang E-mail: martin.winkler@desy.de

    2014-09-01

    The AMS-02 experiment is measuring the cosmic ray antiproton flux with high precision. The interpretation of the upcoming data requires a thorough understanding of the secondary antiproton background. In this work, we employ newly available data of the NA49 experiment at CERN, in order to recalculate the antiproton source term arising from cosmic ray spallations on the interstellar matter. We systematically account for the production of antiprotons via hyperon decay and discuss the possible impact of isospin effects on antineutron production. A detailed comparison of our calculation with the existing literature as well as with Monte Carlo based evaluations of the antiproton source term is provided. Our most important result is an updated prediction for the secondary antiproton flux which includes a realistic assessment of the particle physics uncertainties at all energies.

  9. Cosmic microwave background anisotropies generated by domain wall networks

    NASA Astrophysics Data System (ADS)

    Sousa, L.; Avelino, P. P.

    2015-10-01

    We develop a numerical tool for the fast computation of the temperature and polarization power spectra generated by domain wall networks, by extending the publicly available cmbact code—which calculates the cosmic microwave background signatures generated by active sources—to also describe domain wall networks. In order to achieve this, we adapt the unconnected segment model for cosmic strings to also describe domain wall networks, and use it to model the energy-momentum contribution of domain wall networks throughout their cosmological history. We use this new tool to compute and study the TT, EE, TE and BB power spectra generated by standard domain wall networks, and derive a conservative constraint on the energy scale of the domain wall-forming phase transition of η <0.92 MeV (which is a slight improvement over the original Zel'dovich bound of 1 MeV).

  10. Using Cosmic Microwave Background Lensing to Constrain the Multiplicative Bias of Cosmic Shear

    NASA Astrophysics Data System (ADS)

    Vallinotto, Alberto

    2012-11-01

    Weak gravitational lensing is one of the key probes of cosmology. Cosmic shear surveys aimed at measuring the distribution of matter in the universe are currently being carried out (Pan-STARRS) or planned for the coming decade (DES, LSST, EUCLID, WFIRST). Crucial to the success of these surveys is the control of systematics. In this work, a new method to constrain one such family of systematics, known as multiplicative bias, is proposed. This method exploits the cross-correlation between weak-lensing measurements from galaxy surveys and the ones obtained from high-resolution cosmic microwave background experiments. This cross-correlation is shown to have the power to break the degeneracy between the normalization of the matter power spectrum and the multiplicative bias of cosmic shear and to be able to constrain the latter to a few percent.

  11. USING COSMIC MICROWAVE BACKGROUND LENSING TO CONSTRAIN THE MULTIPLICATIVE BIAS OF COSMIC SHEAR

    SciTech Connect

    Vallinotto, Alberto

    2012-11-01

    Weak gravitational lensing is one of the key probes of cosmology. Cosmic shear surveys aimed at measuring the distribution of matter in the universe are currently being carried out (Pan-STARRS) or planned for the coming decade (DES, LSST, EUCLID, WFIRST). Crucial to the success of these surveys is the control of systematics. In this work, a new method to constrain one such family of systematics, known as multiplicative bias, is proposed. This method exploits the cross-correlation between weak-lensing measurements from galaxy surveys and the ones obtained from high-resolution cosmic microwave background experiments. This cross-correlation is shown to have the power to break the degeneracy between the normalization of the matter power spectrum and the multiplicative bias of cosmic shear and to be able to constrain the latter to a few percent.

  12. Cosmic microwave background and first molecules in the early universe

    NASA Astrophysics Data System (ADS)

    Signore, Monique; Puy, Denis

    2009-01-01

    Besides the Hubble expansion of the universe, the main evidence in favor of the big-bang theory was the discovery, by Penzias and Wilson, of the cosmic microwave background (hereafter CMB) radiation. In 1990, the COBE satellite (Cosmic Background Explorer) revealed an accurate black-body behavior with a temperature around 2.7 K. Although the microwave background is very smooth, the COBE satellite did detect small variations—at the level of one part in 100 000—in the temperature of the CMB from place to place in the sky. These ripples are caused by acoustic oscillations in the primordial plasma. While COBE was only sensitive to long-wavelength waves, the Wilkinson Microwave Anisotropy Probe (WMAP)—with its much higher resolution—reveals that the CMB temperature variations follow the distinctive pattern predicted by cosmological theory. Moreover, the existence of the microwave background allows cosmologists to deduce the conditions present in the early stages of the big bang and, in particular, helps to account for the chemistry of the universe. This report summarizes the latest measurements and studies of the CMB with the new calculations about the formation of primordial molecules. The PLANCK mission—planned to be launched in 2009—is also presented.

  13. Stochastic gravitational wave background from light cosmic strings

    SciTech Connect

    DePies, Matthew R.; Hogan, Craig J.

    2007-06-15

    Spectra of the stochastic gravitational wave backgrounds from cosmic strings are calculated and compared with present and future experimental limits. Motivated by theoretical expectations of light cosmic strings in superstring cosmology, improvements in experimental sensitivity, and recent demonstrations of large, stable loop formation from a primordial network, this study explores a new range of string parameters with masses lighter than previously investigated. A standard 'one-scale' model for string loop formation is assumed. Background spectra are calculated numerically for dimensionless string tensions G{mu}/c{sup 2} between 10{sup -7} and 10{sup -18}, and initial loop sizes as a fraction of the Hubble radius {alpha} from 0.1 to 10{sup -6}. The spectra show a low frequency power-law tail, a broad spectral peak due to loops decaying at the present epoch (including frequencies higher than their fundamental mode, and radiation associated with cusps), and a flat (constant energy density) spectrum at high frequencies due to radiation from loops that decayed during the radiation-dominated era. The string spectrum is distinctive and unlike any other known source. The peak of the spectrum for light strings appears at high frequencies, significantly affecting predicted signals. The spectra of the cosmic string backgrounds are compared with current millisecond pulsar limits and Laser Interferometer Space Antenna (LISA) sensitivity curves. For models with large stable loops ({alpha}=0.1), current pulsar-timing limits exclude G{mu}/c{sup 2}>10{sup -9}, a much tighter limit on string tension than achievable with other techniques, and within the range of current models based on brane inflation. LISA may detect a background from strings as light as G{mu}/c{sup 2}{approx_equal}10{sup -16}, corresponding to field theory strings formed at roughly 10{sup 11} GeV.

  14. PROBING THE UNIVERSE'S TILT WITH THE COSMIC INFRARED BACKGROUND DIPOLE

    SciTech Connect

    Fixsen, D. J.; Kashlinsky, A. E-mail: alexander.kashlinsky@nasa.gov

    2011-06-10

    Conventional interpretation of the observed cosmic microwave background (CMB) dipole is that all of it is produced by local peculiar motions. Alternative explanations requiring part of the dipole to be primordial have received support from measurements of large-scale bulk flows. A test of the two hypotheses is whether other cosmic dipoles produced by collapsed structures later than the last scattering coincide with the CMB dipole. One background is the cosmic infrared background (CIB) whose absolute spectrum was measured to {approx}30% by the COBE satellite. Over the 100-500 {mu}m wavelength range its spectral energy distribution can provide a probe of its alignment with the CMB. This is tested with the COBE FIRAS data set which is available for such a measurement because of its low noise and frequency resolution which are important for Galaxy subtraction. Although the FIRAS instrument noise is in principle low enough to determine the CIB dipole, the Galactic foreground is sufficiently close spectrally to keep the CIB dipole hidden. A similar analysis is performed with DIRBE, which-because of the limited frequency coverage-provides a poorer data set. We discuss strategies for measuring the CIB dipole with future instruments to probe the tilt and apply it to the Planck, Herschel, and the proposed Pixie missions. We demonstrate that a future FIRAS-like instrument with instrument noise a factor of {approx}10 lower than FIRAS would make a statistically significant measurement of the CIB dipole. We find that the Planck and Herschel data sets will not allow a robust CIB dipole measurement. The Pixie instrument promises a determination of the CIB dipole and its alignment with either the CMB dipole or the dipole galaxy acceleration vector.

  15. Anisotropies of the cosmic background radiation by domain wall networks

    SciTech Connect

    Nambu, Yasusada; Ishihara, Hideki; Gouda, Naoteru; Sugiyama, Naoshi )

    1991-06-01

    This paper discusses cosmological effects by domain wall formation associated with a late time phase transition after decoupling. Assuming the existence of rigid domain wall networks, a simple one-dimensional model is constructed and the quadrupole anisotropy of the cosmic background radiation (CBR) is calculated. Contrary to expectation, the gravitational potential of a domain wall itself does not disturb the isotropy of CBR. Estimating the quadrupole anisotropy of CBR induced by the wall-driven growth of matter density perturbations, a 100/h Mpc periodic wall structure is found to be consistent with the observed upper bound. 12 refs.

  16. Introduction to temperature anisotropies of Cosmic Microwave Background radiation

    NASA Astrophysics Data System (ADS)

    Sugiyama, Naoshi

    2014-06-01

    Since its serendipitous discovery, Cosmic Microwave Background (CMB) radiation has been recognized as the most important probe of Big Bang cosmology. This review focuses on temperature anisotropies of CMB which make it possible to establish precision cosmology. Following a brief history of CMB research, the physical processes working on the evolution of CMB anisotropies are discussed, including gravitational redshift, acoustic oscillations, and diffusion dumping. Accordingly, dependencies of the angular power spectrum on various cosmological parameters, such as the baryon density, the matter density, space curvature of the universe, and so on, are examined and intuitive explanations of these dependencies are given.

  17. FINGERPRINTS OF GALACTIC LOOP I ON THE COSMIC MICROWAVE BACKGROUND

    SciTech Connect

    Liu, Hao; Mertsch, Philipp

    2014-07-10

    We investigate possible imprints of galactic foreground structures such as the ''radio loops'' in the derived maps of the cosmic microwave background. Surprisingly, there is evidence for these not only at radio frequencies through their synchrotron radiation, but also at microwave frequencies where emission by dust dominates. This suggests the mechanism is magnetic dipole radiation from dust grains enriched by metallic iron or ferrimagnetic molecules. This new foreground we have identified is present at high galactic latitudes, and potentially dominates over the expected B-mode polarization signal due to primordial gravitational waves from inflation.

  18. Gravitino decay and the cosmic gamma-ray background

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1986-01-01

    It is argued that the cosmic gamma-ray background (CGB) spectrum does not exhibit evidence for the decay of light gravitinos, in contradiction to the suggestion by Olive and Silk (1985), who observed a bump near 1 MeV in the CGB radiation spectrum. It is suggested that better fits to the CGB spectrum would be provided by mechanisms generating a power-law spectrum which is flattened below about 2 MeV. Olive and Silk maintain that the decays of a long-lived particle such as the gravitino may be responsible for features in the gamma-ray spectrum near 1 MeV.

  19. The cosmological microwave background radiation, cosmic and superconducting strings

    NASA Astrophysics Data System (ADS)

    Sanchez, N.; Signore, M.

    1989-03-01

    We study different kinds of anisotropies and distortions in the cosmological background radiation due to cosmic and superconducting strings: (i) temperature angular anisotropy by loop decay into gravitational waves and (ii) spectral distortions due to electromagnetic energy emission. We relate distortions produced by loops indifferent epochs of their evolution. We confront these predictions with observations, in particular with the submillimeter excess recently observed by the Nagoya-Berkeley experiment. This allows us to place constraints both of the string parameter Gμ and on the parameters governing loop evolution. UA 336 Laboratoire Associé au CNRS, Observatoire de Meudon et Ecole Normale Superieure, 24 reu Lhomond, F-75231 Paris Cedex 05, France.

  20. Search for Linear Polarization of the Cosmic Background Radiation

    DOE R&D Accomplishments Database

    Lubin, P. M.; Smoot, G. F.

    1978-10-01

    We present preliminary measurements of the linear polarization of the cosmic microwave background (3 deg K blackbody) radiation. These ground-based measurements are made at 9 mm wavelength. We find no evidence for linear polarization, and set an upper limit for a polarized component of 0.8 m deg K with a 95% confidence level. This implies that the present rate of expansion of the Universe is isotropic to one part in 10{sup 6}, assuming no re-ionization of the primordial plasma after recombination

  1. Fisher Matrix Optimization of Cosmic Microwave Background Interferometry

    NASA Astrophysics Data System (ADS)

    Liu, Haonan; Bunn, Emory F.

    2016-01-01

    We describe a method for forecasting errors in interferometric measurements of polarization of the cosmic microwave background (CMB) radiation, based on the use of the Fisher matrix calculated from the visibility covariance and relation matrices. In addition to noise and sample variance, the method can account for many kinds of systematic error by calculating an augmented Fisher matrix, including parameters that characterize the instrument along with the cosmological parameters to be estimated. The method is illustrated with examples of gain errors and errors in polarizer orientation. The augmented Fisher matrix approach is applicable to a much wider range of problems beyond CMB interferometry.

  2. Cosmic muon background and reactor neutrino detectors: the Angra experiment

    NASA Astrophysics Data System (ADS)

    Casimiro, E.; Anjos, J. C.

    2008-06-01

    We discuss on the importance of appropriately taking into account the cosmic background in the design of reactor neutrino detectors. In particular, as a practical study case, we describe the Angra Project, a new reactor neutrino oscillation experiment proposed to be built in the coming years at the Brazilian nuclear power complex, located near the Angra dos Reis city. The main goal of the experiment is to measure with high precision θ13, the last unknown of the three neutrino mixing angles. The experiment will in addition explore the possibility of using neutrino detectors for purposes of safeguards and non-proliferation of nuclear weapons.

  3. Early reionization by decaying particles and cosmic microwave background radiation

    SciTech Connect

    Kasuya, S.; Kawasaki, M.

    2004-11-15

    We study the reionization scenario in which ionizing UV photons emitted from decaying particle, in addition to usual contributions from stars and quasars, ionize the universe. It is found that the scenario is consistent with both the first year data of the Wilkinson Microwave Anisotropy Probe and the fact that the universe is not fully ionized until z{approx}6 as observed by Sloan Digital Sky Survey. Likelihood analysis revealed that rather broad parameter space can be chosen. This scenario will be discriminated by future observations, especially by the EE polarization power spectrum of cosmic microwave background radiation.

  4. Long-range correlation in cosmic microwave background radiation.

    PubMed

    Movahed, M Sadegh; Ghasemi, F; Rahvar, Sohrab; Tabar, M Reza Rahimi

    2011-08-01

    We investigate the statistical anisotropy and gaussianity of temperature fluctuations of Cosmic Microwave Background (CMB) radiation data from the Wilkinson Microwave Anisotropy Probe survey, using the Multifractal Detrended Fluctuation Analysis, Rescaled Range, and Scaled Windowed Variance methods. Multifractal Detrended Fluctuation Analysis shows that CMB fluctuations has a long-range correlation function with a multifractal behavior. By comparing the shuffled and surrogate series of CMB data, we conclude that the multifractality nature of the temperature fluctuation of CMB radiation is mainly due to the long-range correlations, and the map is consistent with a gaussian distribution. PMID:21928945

  5. Dark energy and the cosmic microwave background radiation.

    PubMed

    Dodelson, S; Knox, L

    2000-04-17

    We find that current cosmic microwave background anisotropy data strongly constrain the mean spatial curvature of the Universe to be near zero, or, equivalently, the total energy density to be near critical-as predicted by inflation. This result is robust to editing of data sets, and variation of other cosmological parameters (totaling seven, including a cosmological constant). Other lines of argument indicate that the energy density of nonrelativistic matter is much less than critical. Together, these results are evidence, independent of supernovae data, for dark energy in the Universe. PMID:11019136

  6. Cosmic microwave background radiation anisotropies in brane worlds.

    PubMed

    Koyama, Kazuya

    2003-11-28

    We propose a new formulation to calculate the cosmic microwave background (CMB) spectrum in the Randall-Sundrum two-brane model based on recent progress in solving the bulk geometry using a low energy approximation. The evolution of the anisotropic stress imprinted on the brane by the 5D Weyl tensor is calculated. An impact of the dark radiation perturbation on the CMB spectrum is investigated in a simple model assuming an initially scale-invariant adiabatic perturbation. The dark radiation perturbation induces isocurvature perturbations, but the resultant spectrum can be quite different from the prediction of simple mixtures of adiabatic and isocurvature perturbations due to Weyl anisotropic stress. PMID:14683226

  7. Fisher matrix optimization of cosmic microwave background interferometers

    NASA Astrophysics Data System (ADS)

    Liu, Haonan; Bunn, Emory F.

    2016-01-01

    We describe a method for forecasting errors in interferometric measurements of polarization of the cosmic microwave background (CMB) radiation, based on the use of the Fisher matrix calculated from the visibility covariance and relation matrices. In addition to noise and sample variance, the method can account for many kinds of systematic error by calculating an augmented Fisher matrix, including parameters that characterize the instrument along with the cosmological parameters to be estimated. The method is illustrated with examples of gain errors and errors in polarizer orientation. The augmented Fisher-matrix approach is applicable to a much wider range of problems beyond CMB interferometry.

  8. Translational invariance and the anisotropy of the cosmic microwave background

    SciTech Connect

    Carroll, Sean M.; Tseng, C.-Y.; Wise, Mark B.

    2010-04-15

    Primordial quantum fluctuations produced by inflation are conventionally assumed to be statistically homogeneous, a consequence of translational invariance. In this paper we quantify the potentially observable effects of a small violation of translational invariance during inflation, as characterized by the presence of a preferred point, line, or plane. We explore the imprint such a violation would leave on the cosmic microwave background anisotropy, and provide explicit formulas for the expected amplitudes of the spherical-harmonic coefficients.

  9. Dark energy and the cosmic microwave background radiation

    NASA Technical Reports Server (NTRS)

    Dodelson, S.; Knox, L.

    2000-01-01

    We find that current cosmic microwave background anisotropy data strongly constrain the mean spatial curvature of the Universe to be near zero, or, equivalently, the total energy density to be near critical-as predicted by inflation. This result is robust to editing of data sets, and variation of other cosmological parameters (totaling seven, including a cosmological constant). Other lines of argument indicate that the energy density of nonrelativistic matter is much less than critical. Together, these results are evidence, independent of supernovae data, for dark energy in the Universe.

  10. COSMIC OPTICAL BACKGROUND: THE VIEW FROM PIONEER 10/11

    SciTech Connect

    Matsuoka, Y.; Oyabu, S.; Ienaka, N.; Kawara, K.

    2011-08-01

    We present the new constraints on the cosmic optical background (COB) obtained from an analysis of the Pioneer 10/11 Imaging Photopolarimeter (IPP) data. After careful examination of data quality, the usable measurements free from the zodiacal light are integrated into sky maps at the blue ({approx}0.44 {mu}m) and red ({approx}0.64 {mu}m) band. Accurate starlight subtraction is achieved by referring to all-sky star catalogs and a Galactic stellar population synthesis model down to 32.0 mag. We find that the residual light is separated into two components: one component shows a clear correlation with thermal 100 {mu}m brightness, while another betrays a constant level in the lowest 100 {mu}m brightness region. The presence of the second component is significant after all the uncertainties and possible residual light in the Galaxy are taken into account, and thus it most likely has the extragalactic origin (i.e., the COB). The derived COB brightness is (1.8 {+-} 0.9) x 10{sup -9} and (1.2 {+-} 0.9) x 10{sup -9} erg s{sup -1} cm{sup -2} sr{sup -1} A{sup -1} at the blue and red bands, respectively, or 7.9 {+-} 4.0 and 7.7 {+-} 5.8 nW m{sup -2} sr{sup -1}. From comparison with the integrated brightness of galaxies, we conclude that bulk of the COB is comprised of normal galaxies which have already been resolved in the current deepest observations. There seems to be little room for contributions of other populations including 'first stars' at these wavelengths. On the other hand, the first component of the IPP residual light represents the diffuse Galactic light (DGL)-scattered starlight by the interstellar dust. We derive mean DGL-to-100 {mu}m brightness ratios of 2.1 x 10{sup -3} and 4.6 x 10{sup -3} at the two bands, which are roughly consistent with the previous observations toward the denser dust regions. Extended red emission in the diffuse interstellar medium is also confirmed.

  11. Prospects for Delensing the Cosmic Microwave Background for Studying Inflation

    NASA Astrophysics Data System (ADS)

    Simard, Gabrielle; Hanson, Duncan; Holder, Gil

    2015-07-01

    A detection of excess cosmic microwave background (CMB) B-mode polarization on large scales allows the possibility of measuring not only the amplitude of these fluctuations but also their scale dependence, which can be parametrized as the tensor tilt nT. Measurements of this scale dependence will be hindered by the secondary B-mode polarization anisotropy induced by gravitational lensing. Fortunately, these contaminating B modes can be estimated and removed with a sufficiently good estimate of the intervening gravitational potential and a good map of CMB E-mode polarization. We present forecasts for how well these gravitational lensing B modes can be removed, assuming that the lensing potential can be estimated either internally from CMB data or using maps of the cosmic infrared background (CIB) as a tracer. We find that CIB maps are as effective as CMB maps for delensing at the noise levels of the current generation of CMB experiments, while the CMB maps themselves will ultimately be best for delensing at polarization noise below {{{Δ }}}{{P}} = 1 μK arcmin. At this sensitivity level, CMB delensing will be able to measure nT to an accuracy of 0.02 or better, which corresponds to the tensor tilt predicted by the consistency relation for single-field slow-roll models of inflation with r = 0.2. However, CIB-based delensing will not be sufficient for constraining nT in simple inflationary models.

  12. Cosmic microwave background bispectrum on small angular scales

    SciTech Connect

    Pitrou, Cyril; Uzan, Jean-Philippe; Bernardeau, Francis

    2008-09-15

    This article investigates the nonlinear evolution of cosmological perturbations on sub-Hubble scales in order to evaluate the unavoidable deviations from Gaussianity that arise from the nonlinear dynamics. It shows that the dominant contribution to modes coupling in the cosmic microwave background temperature anisotropies on small angular scales is driven by the sub-Hubble nonlinear evolution of the dark matter component. The perturbation equations, involving, in particular, the first moments of the Boltzmann equation for photons, are integrated up to second order in perturbations. An analytical analysis of the solutions gives a physical understanding of the result as well as an estimation of its order of magnitude. This allows one to quantify the expected deviation from Gaussianity of the cosmic microwave background temperature anisotropy and, in particular, to compute its bispectrum on small angular scales. Restricting to equilateral configurations, we show that the nonlinear evolution accounts for a contribution that would be equivalent to a constant primordial non-Gaussianity of order f{sub NL}{approx}25 on scales ranging approximately from l{approx}1000 to l{approx}3000.

  13. Cosmic backgrounds of relic gravitons and their absolute normalization

    NASA Astrophysics Data System (ADS)

    Giovannini, Massimo

    2014-11-01

    Provided the consistency relations are not violated, the recent BICEP2 observations pin down the absolute normalization, the spectral slope and the maximal frequency of the cosmic graviton background produced during inflation. The properly normalized spectra are hereby computed from the lowest frequencies (of the order of the present Hubble rate) up to the highest frequency range in the GHz region. Deviations from the conventional paradigm cannot be excluded and are examined by allowing for different physical possibilities including, in particular, a running of the tensor spectral index, an explicit breaking of the consistency relations and a spike in the high-frequency tail of the spectrum coming either from a post-inflationary phase dominated by a stiff fluid or from the contribution of waterfall fields in a hybrid inflationary context. The direct determinations of the tensor to scalar ratio at low frequencies, if confirmed by the forthcoming observations, will also affect and constrain the high-frequency uncertainties. The limits on the cosmic graviton backgrounds coming from wide-band interferometers (such as LIGO/Virgo, LISA and BBO/DECIGO) together with a more accurate scrutiny of the tensor B-mode polarization at low frequencies will set direct bounds on the post-inflationary evolution and on other unconventional completions of the standard lore.

  14. Cosmic string parameter constraints and model analysis using small scale Cosmic Microwave Background data

    SciTech Connect

    Urrestilla, Jon; Bevis, Neil; Hindmarsh, Mark; Kunz, Martin E-mail: n.bevis@imperial.ac.uk E-mail: martin.kunz@physics.unige.ch

    2011-12-01

    We present a significant update of the constraints on the Abelian Higgs cosmic string tension by cosmic microwave background (CMB) data, enabled both by the use of new high-resolution CMB data from suborbital experiments as well as the latest results of the WMAP satellite, and by improved predictions for the impact of Abelian Higgs cosmic strings on the CMB power spectra. The new cosmic string spectra [1] were improved especially for small angular scales, through the use of larger Abelian Higgs string simulations and careful extrapolation. If Abelian Higgs strings are present then we find improved bounds on their contribution to the CMB anisotropies, fd{sup AH} < 0.095, and on their tension, Gμ{sub AH} < 0.57 × 10{sup −6}, both at 95% confidence level using WMAP7 data; and fd{sup AH} < 0.048 and Gμ{sub AH} < 0.42 × 10{sup −6} using all the CMB data. We also find that using all the CMB data, a scale invariant initial perturbation spectrum, n{sub s} = 1, is now disfavoured at 2.4σ even if strings are present. A Bayesian model selection analysis no longer indicates a preference for strings.

  15. The cosmic gamma-ray background from Type Ia supernovae

    NASA Technical Reports Server (NTRS)

    The, Lih-Sin; Leising, Mark D.; Clayton, Donald D.

    1993-01-01

    We present an improved calculation of the cumulative gamma-ray spectrum of Type Ia supernovae during the history of the universe. We follow Clayton & Ward (1975) in using a few Friedmann models and two simple histories of the average galaxian nucleosynthesis rate, but we improve their calculation by modeling the gamma-ray scattering in detailed numerical models of SN Ia's. The results confirm that near 1 MeV the SN Ia background may dominate, and that it is potentially observable, with high scientific importance. A very accurate measurement of the cosmic background spectrum between 0.1 and 1.0 MeV may reveal the turn-on time and the evolution of the rate of Type Ia supernova nucleosynthesis in the universe.

  16. THE MYSTERY OF THE COSMIC DIFFUSE ULTRAVIOLET BACKGROUND RADIATION

    SciTech Connect

    Henry, Richard Conn; Murthy, Jayant; Overduin, James; Tyler, Joshua E-mail: jmurthy@yahoo.com E-mail: 97tyler@cardinalmail.cua.edu

    2015-01-01

    The diffuse cosmic background radiation in the Galaxy Evolution Explorer far-ultraviolet (FUV, 1300-1700 Å) is deduced to originate only partially in the dust-scattered radiation of FUV-emitting stars: the source of a substantial fraction of the FUV background radiation remains a mystery. The radiation is remarkably uniform at both far northern and far southern Galactic latitudes and increases toward lower Galactic latitudes at all Galactic longitudes. We examine speculation that this might be due to interaction of the dark matter with the nuclei of the interstellar medium, but we are unable to point to a plausible mechanism for an effective interaction. We also explore the possibility that we are seeing radiation from bright FUV-emitting stars scattering from a ''second population'' of interstellar grains—grains that are small compared with FUV wavelengths. Such grains are known to exist, and they scatter with very high albedo, with an isotropic scattering pattern. However, comparison with the observed distribution (deduced from their 100 μm emission) of grains at high Galactic latitudes shows no correlation between the grains' location and the observed FUV emission. Our modeling of the FUV scattering by small grains also shows that there must be remarkably few such ''smaller'' grains at high Galactic latitudes, both north and south; this likely means simply that there is very little interstellar dust of any kind at the Galactic poles, in agreement with Perry and Johnston. We also review our limited knowledge of the cosmic diffuse background at ultraviolet wavelengths shortward of Lyα—it could be that our ''second component'' of the diffuse FUV background persists shortward of the Lyman limit and is the cause of the reionization of the universe.

  17. The AGN Population and the Cosmic X-ray Background

    NASA Astrophysics Data System (ADS)

    Treister, Ezequiel; Urry, C. Meg; Schawinski, Kevin

    2015-08-01

    In order to fully understand galaxy formation we need to know when in the cosmic history are supermassive black holes (SMBHs) growing more intensively, in what type of galaxies this growth is happening and what fraction of these sources are invisible at most wavelengths due to obscuration. Active Galactic Nuclei (AGN) population synthesis models that can explain the spectral shape and intensity of the cosmic X-ray background (CXRB) indicate that most of the SMBH growth occurs in moderate-luminosity (Lx~1044 erg/s) sources (Seyfert-type AGN), at z~0.5-1 and in heavily obscured but Compton-thin, NH~1023 cm-2, systems.However, this is not the complete history, as a large fraction of black hole growth does not emit significantly in X-rays either due to obscuration, intrinsic low luminosities or large distances. Using a combination of X-ray stacking and multi wavelength selection techniques we constrain the amount of black hole accretion as a function of cosmic history, from z~0 to z~6. The integrated intensity at high energies indicates that a significant fraction of the total black hole growth, 22%, occurs in heavily-obscured systems that are not individually detected in even the deepest X-ray observations.We finally investigate the AGN triggering mechanism as a function of bolometric luminosity, finding evidence for a strong connection between significant black hole growth events and major galaxy mergers from z~0 to z~3, while less spectacular but longer accretion episodes are most likely due to other (stochastic) processes. AGN activity triggered by major galaxies is responsible for ~60% of the total black hole growth.

  18. Observing the Epoch of Reionization with the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Reichardt, Christian L.

    We review the observable consequences of the epoch of reionization (EoR) on the cosmic microwave background (CMB), and the resulting constraints on the EoR. We discuss how Thomson scattering with the free electrons produced during EoR equates to an optical depth for CMB photons. The optical depth measurements from the WMAP and Planck satellites, using large-scale CMB polarization power spectra, are one of the few current constraints on the timing of cosmic reionization. We also present forecasts for the precision with which the optical depth will be measured by future satellite missions. Second, we consider the kinematic Sunyaev-Zel'dovich (kSZ) effect, and how the kSZ power spectrum depends on the duration of reionization. We review current measurements of the kSZ power and forecasts for future experiments. Finally, we mention proposals to look for spectral distortions in the CMB that are related to the electron temperature at EoR, and ideas to map the variations in the optical depth across the sky.

  19. Re-evaluation of the Cosmic Microwave Background (CMB)

    NASA Astrophysics Data System (ADS)

    Haynes, R.

    2009-12-01

    The cosmic microwave background (CMB) has an almost perfect black-body spectrum, with polarization. These characteristics are inconsistent with the Standard Big Bang (SBB) model. An almost perfect spectrum can arise only from a surface of last scattering which is an almost perfect black-body. Thermodynamically, this is matter in thermal equilibrium, absorbing almost 100% of incident radiation and re-emitting it as black-body radiation. By definition, a perfect black-body is matter at zero kelvin, and cold matter better approaches this perfection. SBB theory describes the CMB as originating from a hydrogen-helium plasma, condensing at a temperature of about 3,000 K. Such a surface would exhibit a continuous radiation spectrum, not unlike that of the sun, which is shown to have a spectrum similar, but not identical to, a black-body spectrum. An imperfect spectrum, even stretched 1100 fold as in the SBB model, remains an imperfect spectrum. Also, a plasma would not support the orientation required to impart polarization to the CMB. A better explanation of the observational evidence is possible if one views the observable universe as part of, and originating from, a much larger structure. Here we propose a defined physical description for such a model. It is shown how a "cosmic fabric" of spin-oriented atomic hydrogen, at zero kelvin, surrounding a matter-depletion zone and the observable universe, would produce the CMB observations. The cosmic fabric would be a perfect black-body and subsequently re-emit an almost perfect black-body spectrum. The radiation would be almost perfectly isotropic, imposed by the spherical distribution of the surface of last scattering, and spin-oriented hydrogen would impart the observed polarization. This geometry also obviates the so-called "horizon problem" of the SBB, why the CMB radiation is essentially isotropic when coming from points of origin with no apparent causal contact. This problem was supposedly "solved" with the

  20. Impact of cosmic neutrinos on the gravitational-wave background

    SciTech Connect

    Mangilli, Anna; Bartolo, Nicola; Matarrese, Sabino; Riotto, Antonio

    2008-10-15

    We obtain the equation governing the evolution of the cosmological gravitational-wave background, accounting for the presence of cosmic neutrinos, up to second order in perturbation theory. In particular, we focus on the epoch during radiation dominance, after neutrino decoupling, when neutrinos yield a relevant contribution to the total energy density and behave as collisionless ultrarelativistic particles. Besides recovering the standard damping effect due to neutrinos, a new source term for gravitational waves is shown to arise from the neutrino anisotropic stress tensor. The importance of such a source term, so far completely disregarded in the literature, is related to the high velocity dispersion of neutrinos in the considered epoch; its computation requires solving the full second-order Boltzmann equation for collisionless neutrinos.

  1. Far Infrared Spectrometry of the Cosmic Background Radiation

    DOE R&D Accomplishments Database

    Mather, J. C.

    1974-01-01

    I describe two experiments to measure the cosmic background radiation near 1 mm wavelength. The first was a ground-based search for spectral lines, made with a Fabry-Perot interferometer and an InSb detector. The second is a measurement of the spectrum from 3 to 18 cm{sup -1}, made with a balloon-borne Fourier transform spectrometer. It is a polarizing Michelson interferometer, cooled in liquid helium, and operated with a germanium bolometer. I give the theory of operation, construction details, and experimental results. The first experiment was successfully completed but the second suffered equipment malfunction on its first flight. I describe the theory of Fourier transformations and give a new understanding of convolutional phase correction computations. I discuss for infrared bolometer calibration procedures, and tabulate test results on nine detectors. I describe methods of improving bolometer sensitivity with immersion optics and with conductive film blackening.

  2. Searching for Faraday rotation in cosmic microwave background polarization

    NASA Astrophysics Data System (ADS)

    Ruiz-Granados, B.; Battaner, E.; Florido, E.

    2016-08-01

    We use the Wilkinson Microwave Anisotropy Probe (WMAP) 9th-year foreground reduced data at 33, 41 and 61 GHz to derive a Faraday rotation at map and at angular power spectrum levels taking into account their observational errors. A processing mask provided by WMAP is used to avoid contamination from the disc of our Galaxy and local spurs. We have found a Faraday rotation component at both, map and power spectrum levels. The lack of correlation of the Faraday rotation with Galactic Faraday rotation, synchrotron and dust polarization from our Galaxy or with cosmic microwave background anisotropies or lensing suggests that it could be originated at reionization (ℓ ≲ 12). Even if the detected Faraday rotation signal is weak, the present study could contribute to establish magnetic fields strengths of B0 ˜ 10-8 G at reionization.

  3. Cosmic microwave background anisotropy from nonlinear structures in accelerating universes

    SciTech Connect

    Sakai, Nobuyuki; Inoue, Kaiki Taro

    2008-09-15

    We study the cosmic microwave background (CMB) anisotropy due to spherically symmetric nonlinear structures in flat universes with dust and a cosmological constant. By modeling a time-evolving spherical compensated void/lump by Lemaitre-Tolman-Bondi spacetimes, we numerically solve the null geodesic equations with the Einstein equations. We find that a nonlinear void redshifts the CMB photons that pass through it regardless of the distance to it. In contrast, a nonlinear lump blueshifts (or redshifts) the CMB photons if it is located near (or sufficiently far from) us. The present analysis comprehensively covers previous works based on a thin-shell approximation and a linear/second-order perturbation method and the effects of shell thickness and full nonlinearity. Our results indicate that, if quasilinear and large (> or approx.100 Mpc) voids/lumps would exist, they could be observed as cold or hot spots with temperature variance > or approx. 10{sup -5} K in the CMB sky.

  4. Development of Superconducting Detectors for Measurements of Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Hattori, K.; Hazumi, M.; Ishino, H.; Kawai, M.; Kibayashi, A.; Kimura, N.; Mima, S.; Noguchi, T.; Okamura, T.; Sato, N.; Tajima, O.; Tomaru, T.; Watanabe, H.; Yoshida, M.

    We present our recent development of superconducting detectors for measurements of cosmic microwave background. We have fabricated antenna-coupled superconducting tunnel junctions (STJs). Two different types of STJs have been fabricated: the parallel-connected twin junction and the microstrip. Both types of STJs made of Nb and Al have successfully detected 80 GHz millimeter wave radiation with photon-assisted tunneling. We have also developed microwave kinetic inductance detectors (MKIDs). The MKIDs offer us high multiplexing factors with a single readout line using the frequency-domain readout. We have developed abosrption-type and transmission-type MKIDs whose resonators are formed with either coplanar waveguides (CPW) or microstrips. The quality factor of the CPW MKID made of Nb is measured to be about 105. The microstrip MKID is being developed for the multichroic measurements.

  5. Patchy screening of the cosmic microwave background by inhomogeneous reionization

    NASA Astrophysics Data System (ADS)

    Gluscevic, Vera; Kamionkowski, Marc; Hanson, Duncan

    2013-02-01

    We derive a constraint on patchy screening of the cosmic microwave background from inhomogeneous reionization using off-diagonal TB and TT correlations in WMAP-7 temperature/polarization data. We interpret this as a constraint on the rms optical-depth fluctuation Δτ as a function of a coherence multipole LC. We relate these parameters to a comoving coherence scale, of bubble size RC, in a phenomenological model where reionization is instantaneous but occurs on a crinkly surface, and also to the bubble size in a model of “Swiss cheese” reionization where bubbles of fixed size are spread over some range of redshifts. The current WMAP data are still too weak, by several orders of magnitude, to constrain reasonable models, but forthcoming Planck and future EPIC data should begin to approach interesting regimes of parameter space. We also present constraints on the parameter space imposed by the recent results from the EDGES experiment.

  6. Searching for stringy topologies in the cosmic microwave background

    SciTech Connect

    Ben-David, Assaf; Rathaus, Ben; Itzhaki, Nissan E-mail: ben.rathaus@gmail.com

    2012-11-01

    We consider a universe with a non-classical stringy topology that has fixed points. We concentrate on the simplest example, an orbifold point, and study its observable imprints on the cosmic microwave background (CMB). We show that an orbifold preserves the Gaussian nature of the temperature fluctuations, yet modifies the angular correlation function. A direct signature of an orbifold is a single circle in the CMB that is invariant under rotation by 180°. Searching the 7-year ILC map of WMAP, we find one candidate circle with high statistical significance. However, a closer look reveals that the temperature profile does not fit an orbifold. We place a lower bound on the distance to an orbifold point at ∼ 85% of the distance to the surface of last scattering.

  7. The small scale power asymmetry in the cosmic microwave background

    SciTech Connect

    Flender, Samuel; Hotchkiss, Shaun E-mail: shaun.hotchkiss@helsinki.fi

    2013-09-01

    We investigate the hemispherical power asymmetry in the cosmic microwave background on small angular scales. We find an anomalously high asymmetry in the multipole range l = 601−2048, with a naive statistical significance of 6.5σ. However, we show that this extreme anomaly is simply a coincidence of three other effects, relativistic power modulation, edge effects from the mask applied, and inter-scale correlations. After correcting for all of these effects, the significance level drops to ∼ 1σ, i.e., there is no anomalous intrinsic asymmetry in the small angular scales. Using this null result, we derive a constraint on a potential dipolar modulation amplitude, A(k) < 0.0045 on the ∼ 10 Mpc-scale, at 95% C.L. This new constraint must be satisfied by any theoretical model attempting to explain the hemispherical asymmetry at large angular scales.

  8. The Cosmic Microwave Background Radiation and its Polarization

    NASA Astrophysics Data System (ADS)

    Wollack, Edward

    2016-03-01

    The cosmic microwave background (CMB) radiation and its faint polarization have provided a unique means to constrain the physical state of the early Universe. Continued advances in instrumentation, observation, and analysis have revealed polarized radiation signatures associated with gravitational lensing and have heightened the prospects for using precision polarimetry to experimentally confront the inflationary paradigm. Characterization of this relic radiation field has the power to constrain or reveal the detailed properties of astroparticle species and long wave gravitational radiation. On going and planned CMB polarization efforts from the ground, balloon, and space borne platforms will be briefly surveyed. Recent community activities by the Inflation Probe Science Interest Group (IPSIG) will also be summarized. NASA PCOS mini-symposium (invited IPSIG talk).

  9. Imprints of spherical nontrivial topologies on the cosmic microwave background.

    PubMed

    Niarchou, Anastasia; Jaffe, Andrew

    2007-08-24

    The apparent low power in the cosmic microwave background (CMB) temperature anisotropy power spectrum derived from the Wilkinson Microwave Anisotropy Probe motivated us to consider the possibility of a nontrivial topology. We focus on simple spherical multiconnected manifolds and discuss their implications for the CMB in terms of the power spectrum, maps, and the correlation matrix. We perform a Bayesian model comparison against the fiducial best-fit cold dark matter model with a cosmological constant based both on the power spectrum and the correlation matrix to assess their statistical significance. We find that the first-year power spectrum shows a slight preference for the truncated cube space, but the three-year data show no evidence for any of these spaces. PMID:17930937

  10. Dipole modulation of cosmic microwave background temperature and polarization

    NASA Astrophysics Data System (ADS)

    Ghosh, Shamik; Kothari, Rahul; Jain, Pankaj; Rath, Pranati K.

    2016-01-01

    We propose a dipole modulation model for the Cosmic Microwave Background Radiation (CMBR) polarization field. We show that the model leads to correlations between l and l+1 multipoles, exactly as in the case of temperature. We obtain results for the case of TE, EE and BB correlations. An anisotropic or inhomogeneous model of primordial power spectrum which leads to such correlations in temperature field also predicts similar correlations in CMBR polarization. We analyze the CMBR temperature and polarization data in order to extract the signal of these correlation between l and l+1 multipoles. Our results for the case of temperature using the latest PLANCK data agree with those obtained by an earlier analysis. A detailed study of the correlation in the polarization data is not possible at present. Hence we restrict ourselves to a preliminary investigation in this case.

  11. High Precision Cosmology with the Cosmic Background Radiation

    NASA Astrophysics Data System (ADS)

    Farhang, Marzieh

    In this thesis we investigate the two cosmic epochs of inflation and recombination, through their imprints on the temperature and polarization anisotropies of the cosmic microwave background radiation. To probe the early universe we develop a map-based maximum-likelihood estimator to measure the amplitude of inflation-induced gravity waves, parametrized by r, from the cosmic microwave background (CMB) polarization maps. Being optimal by construction, the estimator avoids E-B mixing, a possible source of contamination in the tiny B-mode detection, the target of many current and near future CMB experiments. We explore the leakage from the E- to the B-mode of polarization by using this estimator to study the linear response of the B-mode signal at different scales to variations in the E- mode power. Similarly, for various observational cases, we probe the dependence of r measurement on the signal from different scales of E and B polarization. The estimator is used to make forecasts for Spider-like and Planck-like experimental specifications and to investigate the sky-coverage optimization of the Spider-like case. We compare the forecast errors on r to the results from a similar multipole-based estimator which, by ignoring the mode-mixing, sets a lower limit on the achievable error on r. We find that an experiment with Spider-like specifications with fsky ˜ 0:02--0:2 could place a 2sigma r ≈ 0:014 bound (˜ 95% CL), which rises to 0:02 with an ℓ-dependent foreground residual left over from an assumed efficient component separation. For the Planck-like survey, a Galaxy-masked ( fsky = 0:75) sky would give 2sigmar ≈ 0:015, rising to ≈ 0:05 with the foreground residuals. We also use a novel information-based framework to compare how different generations of CMB experiments reveal information about the early universe, through their measurements of r. We also probe the epoch of recombination by investigating possible fluctuations in the free electron fraction Xe

  12. Cosmic Microwave Background Radiation of Black Hole Universe

    NASA Astrophysics Data System (ADS)

    Zhang, Tianxi

    2009-05-01

    Recently, the author has proposed an alternative cosmological model called black hole universe. According to this model, the universe originated from a hot star-like black hole with several solar masses, and gradually grew up through a supermassive black hole with billion solar masses to the present state with hundred billion-trillion solar masses by accreting ambient materials and merging with other black holes. The entire space is structured with infinite layers hierarchically. The innermost three layers are the universe that we are living, the outside called mother universe, and the inside star-like and supermassive black holes called child universes. The outermost layer is infinite in radius and limits to zero for both the mass density and absolute temperature. The observed cosmic microwave background radiation can be explained as the black body radiation of the black hole universe. When a hot and dense star-like black hole accretes its ambient matter and radiation or merges with other black holes, it expands and cools down. In terms of the Planck law of the black body radiation, a possible thermal history of the black hole universe is obtained. The result shows that the temperature of the present universe can be 3 K as observed if the universe originated from a hot star-like black hole. The initial properties (e.g., temperature, angular momentum, etc.) of the star-like black hole are not critical to the present universe, because most matter and radiation are from the mother universe. Therefore, the black hole universe model is also consistent with the observation of the cosmic microwave background radiation.

  13. Another look at distortions of the Cosmic Microwave Background spectrum

    NASA Astrophysics Data System (ADS)

    De Zotti, G.; Negrello, M.; Castex, G.; Lapi, A.; Bonato, M.

    2016-03-01

    We review aspects of Cosmic Microwave Background (CMB) spectral distortions which do not appear to have been fully explored in the literature. In particular, implications of recent evidences of heating of the intergalactic medium (IGM) by feedback from active galactic nuclei are investigated. Taking also into account the IGM heating associated to structure formation, we argue that values of the y parameter of several × 10-6, i.e. a factor of a few below the COBE/FIRAS upper limit, are to be expected. The Compton scattering by the re-ionized plasma also re-processes primordial distortions, adding a y-type contribution. Hence no pure Bose-Einstein-like distortions are to be expected. An assessment of Galactic and extragalactic foregrounds, taking into account the latest results from the Planck satellite as well as the contributions from the strong CII and CO lines from star-forming galaxies, demonstrates that a foreground subtraction accurate enough to fully exploit the PIXIE sensitivity will be extremely challenging. Motivated by this fact we also discuss methods to detect spectral distortions not requiring absolute measurements and show that accurate determinations of the frequency spectrum of the CMB dipole amplitude may substantially improve over COBE/FIRAS limits on distortion parameters. Such improvements may be at reach of next generation CMB anisotropy experiments. The estimated amplitude of the Cosmic Infrared Background (CIB) dipole might be detectable by careful analyses of Planck maps at the highest frequencies. Thus Planck might provide interesting constraints on the CIB intensity, currently known with a simeq 30% uncertainty.

  14. Cosmic microwave background and supernova constraints on quintessence: Concordance regions and target models

    NASA Astrophysics Data System (ADS)

    Caldwell, Robert R.; Doran, Michael

    2004-05-01

    We perform a detailed comparison of the Wilkinson Microwave Anisotropy Probe measurements of the cosmic microwave background (CMB) temperature and polarization anisotropy with the predictions of quintessence cosmological models of dark energy. We consider a wide range of quintessence models, including a constant equation of state, a simply parametrized, time-evolving equation of state, a class of models of early quintessence, and scalar fields with an inverse-power law potential. We also provide a joint fit to the Cosmic Background Imager (CBI) and Arcminute Cosmology Bolometer Array Receiver (ACBAR) CMB data, and the type 1a supernovae. Using these select constraints we identify viable, target models which should prove useful for numerical studies of large scale structure formation, and to rapidly estimate the impact to the concordance region when new or improved observations become available.

  15. Monte Carlo simulation for background study of geophysical inspection with cosmic-ray muons

    NASA Astrophysics Data System (ADS)

    Nishiyama, Ryuichi; Taketa, Akimichi; Miyamoto, Seigo; Kasahara, Katsuaki

    2016-05-01

    Several attempts have been made to obtain a radiographic image inside volcanoes using cosmic-ray muons (muography). Muography is expected to resolve highly heterogeneous density profiles near the surface of volcanoes. However, several prior works have failed to make clear observations due to contamination by background noise. The background contamination leads to an overestimation of the muon flux and consequently a significant underestimation of the density in the target mountains. To investigate the origin of the background noise, we performed a Monte Carlo simulation. The main components of the background noise in muography are found to be low-energy protons, electrons and muons in case of detectors without particle identification and with energy thresholds below 1 GeV. This result was confirmed by comparisons with actual observations of nuclear emulsions. This result will be useful for detector design in future works, and in addition some previous works of muography should be reviewed from the view point of background contamination.

  16. A Flat Universe from High-Resolution Maps of the Cosmic MicrowaveBackground Radiation

    SciTech Connect

    de Bernardis, P.; Ade, P.A.R.; Bock, J.J.; Bond, J.R.; Borrill,J.; Boscaleri, A.; Coble, K.; Crill, B.P.; De Gasperis, G.; Farese, P.C.; Ferreira, P.G.; Ganga, K.; Giacometti, M.; Hivon, E.; Hristov, V.V.; Iacoangeli, A.; Jaffe, A.H.; Lange, A.E.; Martinis, L.; Masi, S.; Mason,P.; Mauskopf, P.D.; Melchiorri, A.; Miglio, L.; Montroy, T.; Netterfield,C.B.; Pascale, E.; Piacentini, F.; Pogosyan, D.; Prunet, S.; Rao, S.; Romeo, G.; Ruhl, J.E.; Scaramuzzi, F.; Sforna, D.; Vittorio, N.

    2000-04-28

    The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K Cosmic Microwave Background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small anisotropies in its temperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the universe. Here we report the first images of resolved structure in the microwave background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground emission. We compute the angular power spectrum of the microwave background, and find a peak at Legendre multipole {ell}{sub peak} = (197 {+-} 6), with an amplitude DT{sub 200} = (69 {+-} 8){mu}K. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favored by standard inflationary scenarios.

  17. Monte Carlo simulation for background study of geophysical inspection with cosmic-ray muons

    NASA Astrophysics Data System (ADS)

    Nishiyama, Ryuichi; Taketa, Akimichi; Miyamoto, Seigo; Kasahara, Katsuaki

    2016-08-01

    Several attempts have been made to obtain a radiographic image inside volcanoes using cosmic-ray muons (muography). Muography is expected to resolve highly heterogeneous density profiles near the surface of volcanoes. However, several prior works have failed to make clear observations due to contamination by background noise. The background contamination leads to an overestimation of the muon flux and consequently a significant underestimation of the density in the target mountains. To investigate the origin of the background noise, we performed a Monte Carlo simulation. The main components of the background noise in muography are found to be low-energy protons, electrons and muons in case of detectors without particle identification and with energy thresholds below 1 GeV. This result was confirmed by comparisons with actual observations of nuclear emulsions. This result will be useful for detector design in future works, and in addition some previous works of muography should be reviewed from the view point of background contamination.

  18. A flat Universe from high-resolution maps of the cosmic microwave background radiation

    PubMed

    de Bernardis P; Ade; Bock; Bond; Borrill; Boscaleri; Coble; Crill; De Gasperis G; Farese; Ferreira; Ganga; Giacometti; Hivon; Hristov; Iacoangeli; Jaffe; Lange; Martinis; Masi; Mason; Mauskopf; Melchiorri; Miglio; Montroy; Netterfield

    2000-04-27

    The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K cosmic microwave background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small anisotropies in its temperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the Universe. Here we report the first images of resolved structure in the microwave background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground emission. We compute the angular power spectrum of the microwave background, and find a peak at Legendre multipole Ipeak = (197 +/- 6), with an amplitude delta T200 = (69 +/- 8) microK. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favoured by standard inflationary models. PMID:10801117

  19. Contamination control program for the Cosmic Background Explorer: An overview

    NASA Technical Reports Server (NTRS)

    Barney, Richard D.

    1990-01-01

    Each of the three state of the art instruments flown aboard NASA's Cosmic Background Explorer (COBE) were designed, fabricated, and integrated using unique contamination control procedures to ensure accurate characterization of the diffuse radiation in the universe. The most stringent surface level cleanliness specifications ever attempted by NASA were required by the Diffuse Infrared Background Experiment (DRIBE) which is located inside a liquid helium cooled dewar along with the Far Infrared Absolute Spectrophotometer (FIRAS). The DRIBE instrument required complex stray radiation suppression that defined a cold primary optical baffle system surface cleanliness level of 100A. The cleanliness levels of the cryogenic FIRAS instrument and the Differential Microwave Radiometer (DMR) which were positioned symmetrically around the dewar were less stringent ranging from 300 to 500A. To achieve these instrument cleanliness levels, the entire flight spacecraft was maintained at level 500A throughout each phase of development. The COBE contamination control program is described along with the difficulties experienced in maintaining the cleanliness quality of personnel and flight hardware throughout instrument assembly.

  20. THE COSMIC INFRARED BACKGROUND EXPERIMENT (CIBER): THE LOW RESOLUTION SPECTROMETER

    SciTech Connect

    Tsumura, K.; Arai, T.; Matsumoto, T.; Matsuura, S.; Murata, K.; Battle, J.; Bock, J.; Brown, S.; Lykke, K.; Smith, A.; Cooray, A.; Hristov, V.; Levenson, L. R.; Mason, P.; Keating, B.; Renbarger, T.; Kim, M. G.; Lee, D. H.; Nam, U. W.; Sullivan, I.; and others

    2013-08-15

    Absolute spectrophotometric measurements of diffuse radiation at 1 {mu}m to 2 {mu}m are crucial to our understanding of the radiative content of the universe from nucleosynthesis since the epoch of reionization, the composition and structure of the zodiacal dust cloud in our solar system, and the diffuse galactic light arising from starlight scattered by interstellar dust. The Low Resolution Spectrometer (LRS) on the rocket-borne Cosmic Infrared Background Experiment is a {lambda}/{Delta}{lambda} {approx} 15-30 absolute spectrophotometer designed to make precision measurements of the absolute near-infrared sky brightness between 0.75 {mu}m <{lambda} < 2.1 {mu}m. This paper presents the optical, mechanical, and electronic design of the LRS, as well as the ground testing, characterization, and calibration measurements undertaken before flight to verify its performance. The LRS is shown to work to specifications, achieving the necessary optical and sensitivity performance. We describe our understanding and control of sources of systematic error for absolute photometry of the near-infrared extragalactic background light.

  1. Large-Angular-Scale Anisotropy in the Cosmic Background Radiation

    DOE R&D Accomplishments Database

    Gorenstein, M. V.; Smoot, G. F.

    1980-05-01

    We report the results of an extended series of airborne measurements of large-angular-scale anisotropy in the 3 K cosmic background radiation. Observations were carried out with a dual-antenna microwave radiometer operating at 33 GHz (.089 cm wavelength) flown on board a U-2 aircraft to 20 km altitude. In eleven flights, between December 1976 and May 1978, the radiometer measured differential intensity between pairs of directions distributed over most of the northern hemisphere with an rms sensitivity of 47 mK Hz{sup 1�}. The measurements how clear evidence of anisotropy that is readily interpreted as due to the solar motion relative to the sources of the radiation. The anisotropy is well fit by a first order spherical harmonic of amplitude 360{+ or -}50km sec{sup -1} toward the direction 11.2{+ or -}0.5 hours of right ascension and 19 {+ or -}8 degrees declination. A simultaneous fit to a combined hypotheses of dipole and quadrupole angular distributions places a 1 mK limit on the amplitude of most components of quadrupole anisotropy with 90% confidence. Additional analysis places a 0.5 mK limit on uncorrelated fluctuations (sky-roughness) in the 3 K background on an angular scale of the antenna beam width, about 7 degrees.

  2. The Cosmic Infrared Background Experiment (CIBER): The Low Resolution Spectrometer

    NASA Astrophysics Data System (ADS)

    Tsumura, K.; Arai, T.; Battle, J.; Bock, J.; Brown, S.; Cooray, A.; Hristov, V.; Keating, B.; Kim, M. G.; Lee, D. H.; Levenson, L. R.; Lykke, K.; Mason, P.; Matsumoto, T.; Matsuura, S.; Murata, K.; Nam, U. W.; Renbarger, T.; Smith, A.; Sullivan, I.; Suzuki, K.; Wada, T.; Zemcov, M.

    2013-08-01

    Absolute spectrophotometric measurements of diffuse radiation at 1 μm to 2 μm are crucial to our understanding of the radiative content of the universe from nucleosynthesis since the epoch of reionization, the composition and structure of the zodiacal dust cloud in our solar system, and the diffuse galactic light arising from starlight scattered by interstellar dust. The Low Resolution Spectrometer (LRS) on the rocket-borne Cosmic Infrared Background Experiment is a λ/Δλ ~ 15-30 absolute spectrophotometer designed to make precision measurements of the absolute near-infrared sky brightness between 0.75 μm <λ < 2.1 μm. This paper presents the optical, mechanical, and electronic design of the LRS, as well as the ground testing, characterization, and calibration measurements undertaken before flight to verify its performance. The LRS is shown to work to specifications, achieving the necessary optical and sensitivity performance. We describe our understanding and control of sources of systematic error for absolute photometry of the near-infrared extragalactic background light.

  3. Radiometer system to map the cosmic background radiation.

    PubMed

    Gorenstein, M V; Muller, R A; Smoot, G F; Tyson, J A

    1978-04-01

    We have developed a 33-GHz airborne radiometer system to map large angular scale variations in the temperature of the 3 K cosmic background radiation. A ferrite circulator switches a room-temperature mixer between two antennas pointing 60 degrees apart in the sky. In 40 min of observing, the radiometer can measure the anisotropy of the microwave background with an accuracy of +/-1 mK rms, or about 1 part in 3000 of 3 K. The apparatus is flown in a U-2 jet to 20 km altitude where 33-GHz thermal microwave emission from the atmosphere is at a low level. A second radiometer, tuned to 54 GHz near oxygen emission lines, monitors spurious signals from residual atmospheric radiation. The antennas, which have an extremely low side-lobe response of less than -65 dB past 60 degrees , reject anisotropic radiation from the earth's surface. Periodic interchange of the antenna positions and reversal of the aircraft's flight direction cancel equipment-based imbalances. The system has been operated successfully in U-2 aircraft flown from NASA-Ames at Moffett Field, CA. PMID:18699121

  4. Contamination control program for the Cosmic Background Explorer

    NASA Technical Reports Server (NTRS)

    Barney, Richard D.

    1991-01-01

    Each of the three state of the art instruments flown aboard NASA's Cosmic Background Explorer (COBE) were designed, fabricated, and integrated using unique contamination control procedures to ensure accurate characterization of the diffuse radiation in the universe. The most stringent surface level cleanliness specifications ever attempted by NASA were required by the Diffuse Infrared Background Experiment (DRIBE) which is located inside a liquid helium cooled dewar along with the Far Infrared Absolute Spectrophotometer (FIRAS). The DRIBE instrument required complex stray radiation suppression that defined a cold primary optical baffle system surface cleanliness level of 100A. The cleanliness levels of the cryogenic FIRAS instrument and the Differential Microwave Radiometer (DMR) which were positioned symmetrically around the dewar were less stringent ranging from 300 to 500A. To achieve these instrument cleanliness levels, the entire flight spacecraft was maintained at level 500A throughout each phase of development. The COBE contamination control program is described along with the difficulties experienced in maintaining the cleanliness quality of personnel and flight hardware throughout instrument assembly.

  5. Near-IR Extragalactic Background Results from the Cosmic Infrared Background Experiment (CIBER)

    NASA Astrophysics Data System (ADS)

    Zemcov, Michael B.; CIBER

    2016-01-01

    The near IR extragalactic background light (EBL) encodes the integrated light production over cosmic history, so represents the total emission from all galaxies along the line of sight up to ancient first-light objects present during the epoch of reionization (EOR). This EOR emission necessarily comprises part of the background, and indeed a minimum level is required to supply enough photons to ionize the intergalactic medium, corresponding to an EBL brightness less than 1 nW m^-2 sr^-1, about one tenth of the integrated galactic light (IGL). In addition to emission from these IGL and EOR populations, low surface brightness tidal streams of stars stripped by gravitational interactions during galaxy formation at low redshifts, called intrahalo light (IHL), may also contribute a significant fraction of the EBL. Models for these components can be constrained both through direct photometric measurements, as well as the new technique of EBL anisotropy intensity mapping that takes advantage of the fact that the Zodiacal Light is spatially smooth while distant populations produce anisotropies with distinct spatial and spectral characteristics. This talk will present recent results from the Cosmic Infrared Background Experiment (CIBER), a sounding rocket borne payload designed to measure both the fluctuations and direct photometric emission of the extra-galactic background light. The anisotropy of the near-IR EBL suggests the presence of a bright component approximately as bright as the IGL component near 1 micron which we interpret as the aggregate emission from low-redshift IHL. New direct photometric measurements from CIBER's low resolution spectrometer will also be discussed.

  6. Cosmic microwave background constraint on residual annihilations of relic particles

    SciTech Connect

    McDonald, Patrick; Scherrer, Robert J.; Walker, Terry P.

    2001-01-15

    Energy injected into the cosmic microwave background at redshifts z{approx}<10{sup 6} will distort its spectrum permanently. In this paper we discuss the distortion caused by annihilations of relic particles. We use the observational bounds on deviations from a Planck spectrum to constrain a combination of annihilation cross section, mass, and abundance. For particles with an (s-wave) annihilation cross section <{sigma}|v|>(equivalent to){sigma}{sub 0}, the bound is f(m{sub X}/MeV){sup -1}[({sigma}{sub 0}/6x10{sup -27} cm{sup 3}s{sup -1})({Omega}{sub X{bar X}}h{sup 2}){sup 2}]<0.2, where m{sub X} is the particle mass, {Omega}{sub X{bar X}} is the fraction of the critical density the particle and its antiparticle contribute if they survive to the present time, h=H{sub 0}/100 kms{sup -1}Mpc{sup -1}, H{sub 0} is the Hubble constant, and f is the fraction of the annihilation energy that interacts electromagnetically. We also compute the less stringent limits for p-wave annihilation. We update other bounds on residual annihilations and compare them to our CMB bound.

  7. Planck Visualization Project: Seeing and Hearing the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    van der Veen, J.

    2010-08-01

    The Planck Mission, launched May 14, 2009, will measure the sky over nine frequency channels, with temperature sensitivity of a few microKelvin, and angular resolution of up to 5 arc minutes. Planck is expected to provide the data needed to set tight constraints on cosmological parameters, study the ionization history of the Universe, probe the dynamics of the inflationary era, and test fundamental physics. The Planck Education and Public Outreach collaborators at NASA's Jet Propulsion Laboratory, the University of California, Santa Barbara and Purdue University are preparing a variety of materials to present the science goals of the Planck Mission to the public. Two products currently under development are an interactive simulation of the mission which can be run in a virtual reality environment, and an interactive presentation on interpreting the power spectrum of the Cosmic Microwave Background with music. In this paper we present a brief overview of CMB research and the Planck Mission, and discuss how to explain, to non-technical audiences, the theory of how we derive information about the early universe from the power spectrum of the CMB by using the physics of music.

  8. The cut-sky cosmic microwave background is not anomalous

    SciTech Connect

    Pontzen, Andrew; Peiris, Hiranya V.

    2010-05-15

    The observed angular correlation function of the cosmic microwave background has previously been reported to be anomalous, particularly when measured in regions of the sky uncontaminated by Galactic emission. Recent work by Efstathiou et al. presents a Bayesian comparison of isotropic theories, casting doubt on the significance of the purported anomaly. We extend this analysis to all anisotropic Gaussian theories with vanishing mean (<{delta}T>=0), using the much wider class of models to confirm that the anomaly is not likely to point to new physics. On the other hand if there is any new physics to be gleaned, it results from low-l alignments which will be better quantified by a full-sky statistic. We also consider quadratic maximum likelihood power spectrum estimators that are constructed assuming isotropy. The underlying assumptions are therefore false if the ensemble is anisotropic. Nonetheless we demonstrate that, for theories compatible with the observed sky, these estimators (while no longer optimal) remain statistically superior to pseudo-C{sub l} power spectrum estimators.

  9. Testing cosmic microwave background polarization data using position angles

    NASA Astrophysics Data System (ADS)

    Preece, Michael; Battye, Richard A.

    2014-10-01

    We consider a novel null test for contamination which can be applied to cosmic microwave background (CMB) polarization data that involves analysis of the statistics of the polarization position angles. Specifically, we will concentrate on using histograms of the measured position angles to illustrate the idea. Such a test has been used to identify systematics in the NRAO-VLA Sky Survey point source catalogue with an amplitude well below the noise level. We explore the statistical properties of polarization angles in CMB maps. If the polarization angle is not correlated between pixels, then the errors follow a simple √{N_{pix}} law. However, this is typically not the case for CMB maps since these have correlations which result in an increase in the variance as the effective number of independent pixels is reduced. Then, we illustrate how certain classes of systematic errors can result in very obvious patterns in these histograms, and thus that these errors could possibly be identified using this method. We discuss how this idea might be applied in a realistic context, and make a preliminary analysis of the Wilkinson Microwave Anisotropy Probe 7 data, finding evidence of a systematic error in the Q- and W- band data, consistent with a constant offset in Q and U.

  10. A map of the cosmic background radiation at 3 millimeters

    NASA Technical Reports Server (NTRS)

    Lubin, P.; Villela, T.; Epstein, G.; Smoot, G.

    1985-01-01

    Data from a series of balloon flights covering both the Northern and Southern Hemispheres, measuring the large angular scale anisotropy in the cosmic background radiation at 3.3 mm wavelength are presented. The data cover 85 percent of the sky to a limiting sensitivity of 0.7 mK per 7 deg field of view. The data show a 50-sigma (statistical error only) dipole anisotropy with an amplitude of 3.44 + or - 0.17 mK and a direction of alpha = 11.2 h + or - 0.1 h, and delta = -6.0 deg + or - 1.5 deg. A 90 percent confidence level upper limit of 0.00007 is obtained for the rms quadrupole amplitude. Flights separated by 6 months show the motion of earth around the sun. Galactic contamination is very small, with less than 0.1 mK contribution to the dipole quadrupole terms. A map of the sky has been generated from the data.

  11. Measuring the Cosmic Microwave Background Polarization with SPT-POL

    NASA Astrophysics Data System (ADS)

    Crites, Abigail; SPT-POL Collaboration

    2013-01-01

    A new polarization-sensitive camera, SPT-POL, designed to measure the polarization of the cosmic microwave background (CMB), was deployed on the 10 meter South Pole Telescope in January 2012. The goal of the project is to exploit the high resolution of the telescope (1 arcminute beam) and the high sensitivity afforded by the 1536 detector camera to characterize the B-mode polarization induced by the gravitational lensing of the primordial E-mode CMB polarization, as well as to detect or set an upper limit on the level of the B-mode polarization from inflationary gravitational waves. The lensing B-modes will be used to constrain the sum of the neutrino masses by measuring large scale structure, while the inflationary B-modes are sensitive to the energy scale of inflation. I will discuss the development of the SPT-POL camera including the cryogenic design and the transition edge sensor (TES) detectors as well as the science goals and status of the ongoing of the SPT-POL program.

  12. Spectral distortions in the cosmic microwave background polarization

    SciTech Connect

    Renaux-Petel, Sébastien; Fidler, Christian; Pitrou, Cyril; Pettinari, Guido W. E-mail: christian.fidler@port.ac.uk E-mail: g.pettinari@sussex.ac.uk

    2014-03-01

    We compute the spectral distortions of the Cosmic Microwave Background (CMB) polarization induced by non-linear effects in the Compton interactions between CMB photons and the flow of intergalactic electrons. This signal is of the y-type and is dominated by contributions arising from the reionized era. We stress that it is not shadowed by the thermal SZ effect which has no equivalent for polarization. We decompose its angular dependence into E- and B-modes, and we calculate the corresponding power spectra, both exactly and using a suitable Limber approximation that allows a simpler numerical evaluation. We find that B-modes are of the same order of magnitude as E-modes. Both spectra are relatively flat, peaking around ℓ = 280, and their overall amplitude is directly related to the optical depth to reionization. Moreover, we find this effect to be one order of magnitude larger than the non-linear kinetic Sunyaev-Zel'dovich effect in galaxy clusters. Finally, we discuss how to improve the detectability of our signal by cross-correlating it with other quantities sourced by the flow of intergalactic electrons.

  13. Cosmic Background Radiation and “ether-drift” experiments

    NASA Astrophysics Data System (ADS)

    Consoli, M.; Pluchino, A.; Rapisarda, A.

    2016-01-01

    “Ether-drift” experiments have played a crucial role for the origin of relativity. Though, a recent re-analysis shows that those original measurements where light was still propagating in gaseous systems, differently from the modern experiments in vacuum and in solid dielectrics, indicate a small universal anisotropy which is naturally interpreted in terms of a non-local thermal gradient. We argue that this could possibly be the effect, on weakly bound gaseous matter, of the temperature gradient due to the Earth's motion within the Cosmic Background Radiation (CBR). Therefore, a check with modern laser interferometers is needed to reproduce the conditions of those early measurements with today's much greater accuracy. We emphasize that an unambiguous confirmation of our interpretation would have far-reaching consequences. For instance, it would imply that all physical systems on the moving Earth are exposed to a tiny energy flow, an effect which, in principle, could also induce forms of self-organization in matter.

  14. OBSERVATIONAL SCAN-INDUCED ARTIFICIAL COSMIC MICROWAVE BACKGROUND ANISOTROPY

    SciTech Connect

    Liu Hao; Li Tipei E-mail: litp@tsinghua.edu.cn

    2011-05-10

    Reliably detecting the cosmic microwave background (CMB) anisotropy is of great importance in understanding the birth and evolution of the universe. One of the difficulties in CMB experiments is the domination of measured CMB anisotropy maps by the Doppler dipole moment from the motion of the antenna relative to the CMB. For each measured temperature, the expected dipole component has to be calculated separately and then subtracted from the data. A small error in dipole direction, antenna pointing direction, sidelobe pickup contamination, and/or timing synchronism can introduce a significant deviation in the dipole-cleaned CMB temperature. After a full-sky observational scan, the accumulated deviations will be structured with a pattern closely correlated with the observation pattern with artificial anisotropies, including artificial quadrupole, octupole, etc., on large scales in the final CMB map. Such scan-induced anisotropies on large scales can be predicted by the true dipole moment and observational scan scheme. Indeed, the expected scan-induced quadrupole pattern of the Wilkinson Microwave Anisotropy Probe (WMAP) mission is perfectly in agreement with the published WMAP quadrupole. With the scan strategy of the Planck mission, we predict that scan-induced anisotropies will also produce an artificially aligned quadrupole. The scan-induced anisotropy is a common problem for all sweep missions and, like the foreground emissions, has to be removed from observed maps. Without doing so, CMB maps from COBE, WMAP, and Planck are not reliable for studying the CMB anisotropy.

  15. Herschel/PEP Dissects the Cosmic Infrared Background

    NASA Astrophysics Data System (ADS)

    Berta, S.; Magnelli, B.; Nordon, R.; Lutz, D.; Pep Team

    2011-10-01

    Using data from the PACS Evolutionary Probe (PEP) survey, we study the cosmic far-infrared background (CIB) in GOODS-N, GOODS-S, Lockman Hole, COSMOS and Abell 2218. Number counts cover more than two orders of magnitude in flux, from ˜1 mJy to few hundreds mJy. Stacking of 24 μm sources and P(D) statistics extend the analysis down to sub-mJy regimes. CIB surface brightnesses are νIν = 3.61 ± 1.12, 8.04 ± 1.39 and 8.84 ± 1.11 [nW m-2 sr-1] at 70, 100, and 160 μm, respectively. These correspond to 56 ± 10% and 70 ± 9% of the direct measurements at 100 and 160 μm. Through P(D) analysis, these fractions increase to ˜60% and ˜82%. Most of the resolved CIB was radiated at z ≤ 1.0, red sources lying at higher redshift than blue ones.

  16. Reionization during the dark ages from a cosmic axion background

    NASA Astrophysics Data System (ADS)

    Evoli, Carmelo; Leo, Matteo; Mirizzi, Alessandro; Montanino, Daniele

    2016-05-01

    Recently it has been pointed out that a cosmic background of relativistic axion-like particles (ALPs) would be produced by the primordial decays of heavy fields in the post-inflation epoch, contributing to the extra-radiation content in the Universe today. Primordial magnetic fields would trigger conversions of these ALPs into sub-MeV photons during the dark ages. This photon flux would produce an early reionization of the Universe, leaving a significant imprint on the total optical depth to recombination τ. Using the current measurement of τ and the limit on the extra-radiation content Δ Neff by the Planck experiment we put a strong bound on the ALP-photon conversions. Namely we obtain upper limits on the product of the photon-ALP coupling constant gaγ times the magnetic field strength B down to gaγ B gtrsim 6 × 10‑18 GeV‑1 nG for ultralight ALPs.

  17. Cosmic Microwave Background Maps from the HACME Experiment

    NASA Astrophysics Data System (ADS)

    Tegmark, Max; de Oliveira-Costa, Angélica; Staren, John W.; Meinhold, Peter R.; Lubin, Philip M.; Childers, Jeffrey D.; Figueiredo, Newton; Gaier, Todd; Lim, Mark A.; Seiffert, Michael D.; Villela, Thyrso; Wuensche, C. Alexandre

    2000-10-01

    We present cosmic microwave background (CMB) maps from the Santa Barbara HACME balloon experiment (Staren et al.), covering about 1150 square degrees split between two regions in the northern sky, near the stars γ Ursae Minoris and α Leonis, respectively. The FWHM of the beam is ~0.77d in three frequency bands centered on 39, 41, and 43 GHz. The results demonstrate that the thoroughly interconnected scan strategy employed allows efficient removal of 1/f-noise and slightly variable scan-synchronous offsets. The maps display no striping, and the noise correlations are found to be virtually isotropic, decaying on an angular scale ~1°. The noise performance of the experiment resulted in an upper limit on CMB anisotropy. However, our results demonstrate that atmospheric contamination and other systematics resulting from the circular scanning strategy can be accurately controlled and bode well for the planned follow-up experiments BEAST and ACE, since they show that even with the overly cautious assumption that 1/f-noise and offsets will be as dominant as for HACME, the problems they pose can be readily overcome with the mapmaking algorithm discussed. Our prewhitened notch-filter algorithm for destriping and offset removal is proving useful also for other balloon- and ground-based experiments whose scan strategies involve substantial interleaving, e.g., Boomerang.

  18. Distinguishing between inflationary models from cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Tsujikawa, Shinji

    2014-06-01

    In this paper, inflationary cosmology is reviewed, paying particular attention to its observational signatures associated with large-scale density perturbations generated from quantum fluctuations. In the most general scalar-tensor theories with second-order equations of motion, we derive the scalar spectral index n_s, the tensor-to-scalar ratio r, and the nonlinear estimator f_{NL} of primordial non-Gaussianities to confront models with observations of cosmic microwave background (CMB) temperature anisotropies. Our analysis includes models such as potential-driven slow-roll inflation, k-inflation, Starobinsky inflation, and Higgs inflation with non-minimal/derivative/Galileon couplings. We constrain a host of inflationary models by using the Planck data combined with other measurements to find models most favored observationally in the current literature. We also study anisotropic inflation based on a scalar coupling with a vector (or two-form) field and discuss its observational signatures appearing in the two-point and three-point correlation functions of scalar and tensor perturbations.

  19. Reionization and the cosmic microwave background in an open universe

    NASA Technical Reports Server (NTRS)

    Persi, Fred M.

    1995-01-01

    If the universe was reionized at high reshift (z greater than or approximately equal to 30) or never recombined, then photon-electron scattering can erase fluctuations in the cosmic microwave background at scales less than or approximately equal to 1 deg. Peculiar motion at the surface of last scattering will then have given rise to new anisotropy at the 1 min level through the Vishniac effect. Here the observed fluctuations in galaxy counts are extrapolated to high redshifts using linear theory, and the expected anisotropy is computed. The predicted level of anisotropies is a function of Omega(sub 0) and the ratio of the density in ionized baryons to the critical density and is shown to depend strongly on the large- and small-scale power. It is not possible to make general statements about the viability of all reionized models based on current observations, but it is possible to rule out specific models for structure formation, particularly those with high baryonic content or small-scale power. The induced fluctuations are shown to scale with cosmological parameters and optical depth.

  20. Extreme value statistics of cosmic microwave background lensing deflection angles

    NASA Astrophysics Data System (ADS)

    Merkel, Philipp M.; Schäfer, Björn Malte

    2015-10-01

    The smaller the angular scales on which the anisotropies of the cosmic microwave background (CMB) are probed the more important their distortion due to gravitational lensing becomes. Here we investigate the maxima and minima of the CMB lensing deflection field using general extreme value statistics. Since general extreme value statistics applies to uncorrelated data in first place, we consider appropriately low-pass-filtered deflection maps. Besides the suppression of correlations filtering is required for another reason: the lensing field itself is not directly observable but needs to be (statistically) reconstructed from the lensed CMB by means of a quadratic estimator. This reconstruction, though, is noise dominated and therefore requires smoothing too. In idealized Gaussian realizations as well as in realistically reconstructed data, we find that both maxima and minima of the deflection angle components follow consistently a general extreme value distribution of Weibull type. However, its shape, location and scale parameters vary significantly between different realizations. The statistics' potential power to constrain cosmological models appears, therefore, rather limited.

  1. How massless neutrinos affect the cosmic microwave background damping tail

    NASA Astrophysics Data System (ADS)

    Hou, Zhen; Keisler, Ryan; Knox, Lloyd; Millea, Marius; Reichardt, Christian

    2013-04-01

    We explore the physical origin and robustness of constraints on the energy density in relativistic species prior to and during recombination, often expressed as constraints on an effective number of neutrino species, Neff. If the primordial helium abundance, YP, follows the prediction of the big bang nucleosynthesis (BBN) theory, the constraint on Neff from current cosmic microwave background anisotropy data is almost entirely due to the impact of the neutrinos on the expansion rate, and how those changes to the expansion rate alter the ratio of the photon diffusion scale to the sound horizon scale at recombination. We demonstrate that, as long as the primordial helium abundance is derived in a BBN-consistent manner, the constraint on Neff degrades little after marginalizing over AeISW, the phenomenological parameter characterizing the amplitude of the early Integrated Sachs-Wolfe (ISW) effect. We also provide a first determination of AeISW. Varying the YP also changes the ratio of damping to sound horizon scales. We study the physical effects that prevent the resulting near degeneracy between Neff and YP from being a complete one and find that the early ISW effect does play a role in breaking this degeneracy. Examining light-element abundance measurements, we see no significant evidence for the evolution of Neff and the baryon-to-photon ratio from the epoch of BBN to decoupling. Finally, we consider measurements of the distance-redshift relation at low to intermediate redshifts and their implications for the value of Neff.

  2. A circular polarimeter for the Cosmic Microwave Background

    SciTech Connect

    Giovannini, Massimo

    2010-08-01

    A primordial degree of circular polarization of the Cosmic Microwave Background is not observationally excluded. The hypothesis of primordial dichroism can be quantitatively falsified if the plasma is magnetized prior to photon decoupling since the initial V-mode polarization affects the evolution of the temperature fluctuations as well as the equations for the linear polarization. The observed values of the temperature and polarization angular power spectra are used to infer constraints on the amplitude and on the spectral slope of the primordial V-mode. Prior to photon decoupling magnetic fields play the role of polarimeters insofar as they unveil the circular dichroism by coupling the V-mode power spectrum to the remaining brightness perturbations. Conversely, for angular scales ranging between 4 deg and 10 deg the joined bounds on the magnitude of circular polarization and on the magnetic field intensity suggest that direct limits on the V-mode power spectrum in the range of 0.01 mK could directly rule out pre-decoupling magnetic fields in the range of 10–100 nG. The frequency dependence of the signal is located, for the present purposes, in the GHz range.

  3. Cosmic Background Explorer (COBE) transfer orbit attitude control system

    NASA Technical Reports Server (NTRS)

    Placanica, Samuel J.; Flatley, Thomas W.

    1986-01-01

    The Cosmic Background Explorer (COBE) spacecraft will be launched by the Shuttle from Vandenberg AFB into a 300 km altitude, 99 deg inclination, 6 a.m. or 6 p.m. ascending node orbit. After release from the Remote Manipulator System (RMS) arm, an on-board monopropellant hydrazine propulsion system will raise the orbit altitude to 900 km. The spacecraft continuously spins during transfer orbit operations with the spin axis nominally horizontal and in or near the orbit plane. The blowdown propulsion system consists of twelve 5 lb thrusters (3 'spin', 3 'despin', and 6 'axial') with the latter providing initially 30 lb of force parallel to the spin axis for orbit raising. The spin/despin jets provide a constant roll rate during the transfer orbit phase of the mission and the axials control pitch and yaw. The axial thrusters are pulsed on for attitude control during coast periods and are normally on- and off-modulated for control during orbit raising. Attitude sensors employed in the control loops include an array of two-axis digital sun sensors and three planar earth scanners for position measurements, as well as six gyroscopes for rate information. System redundancy is achieved by means of unique three-axes-in-a-plane geometry. This triaxial concept results in a fail-safe operational system with no performance degradation for many different component failure modes.

  4. Constraining light gravitino mass from cosmic microwave background

    SciTech Connect

    Ichikawa, Kazuhide; Kawasaki, Masahiro; Nakayama, Kazunori; Sekiguchi, Toyokazu; Takahashi, Tomo E-mail: kawasaki@icrr.u-tokyo.ac.jp E-mail: sekiguti@icrr.u-tokyo.ac.jp

    2009-08-01

    We investigate the possibilities of constraining the light gravitino mass m{sub 3/2} from future cosmic microwave background (CMB) surveys. A model with light gravitino with the mass m{sub 3/2} < O(10) eV is of great interest since it is free from the cosmological gravitino problem and, in addition, can be compatible with many baryogenesis/leptogenesis scenarios such as the thermal leptogenesis. We show that the lensing of CMB anisotropies can be a good probe for m{sub 3/2} and obtain an expected constraint on m{sub 3/2} from precise measurements of lensing potential in the future CMB surveys, such as the PolarBeaR and CMBpol experiments. If the gravitino mass is m{sub 3/2} = 1 eV, we will obtain the constraint for the gravitino mass as m{sub 3/2} ≤ 3.2 eV (95%C.L.) for the case with Planck+PolarBeaR combined and m{sub 3/2} = 1.04{sup +0.22}{sub −0.26} eV (68%C.L.) for CMBpol. The issue of Bayesian model selection is also discussed.

  5. The information content of cosmic microwave background anisotropies

    NASA Astrophysics Data System (ADS)

    Scott, Douglas; Contreras, Dagoberto; Narimani, Ali; Ma, Yin-Zhe

    2016-06-01

    The cosmic microwave background (CMB) contains perturbations that are close to Gaussian and isotropic. This means that its information content, in the sense of the ability to constrain cosmological models, is closely related to the number of modes probed in CMB power spectra. Rather than making forecasts for specific experimental setups, here we take a more pedagogical approach and ask how much information we can extract from the CMB if we are only limited by sample variance. We show that, compared with temperature measurements, the addition of E-mode polarization doubles the number of modes available out to a fixed maximum multipole, provided that all of the TT, TE, and EE power spectra are measured. However, the situation in terms of constraints on particular parameters is more complicated, as we explain and illustrate graphically. We also discuss the enhancements in information that can come from adding B-mode polarization and gravitational lensing. We show how well one could ever determine the basic cosmological parameters from CMB data compared with what has been achieved with Planck, which has already probed a substantial fraction of the TT information. Lastly, we look at constraints on neutrino mass as a specific example of how lensing information improves future prospects beyond the current 6-parameter model.

  6. Reconstructing patchy reionization from the cosmic microwave background

    SciTech Connect

    Dvorkin, Cora; Smith, Kendrick M.

    2009-02-15

    We introduce a new statistical technique for extracting the inhomogeneous reionization signal from future high-sensitivity measurements of the cosmic microwave background (CMB) temperature and polarization fields. If reionization is inhomogeneous, then the optical depth to recombination will be a function {tau}(n-circumflex) of position on the sky. Anisotropies in {tau}(n-circumflex) alter the statistics of the observed CMB via several physical mechanisms: screening of the surface of last scattering, generation of new polarization via Thomson scattering from reionization bubbles, and the kinetic Sunyaev-Zel'dovich effect. We construct a quadratic estimator {tau}-circumflex{sub lm} for the modes of the {tau} field. This estimator separates the patchy reionization signal from the CMB in the form of a noisy map, which can be cross correlated with other probes of reionization or used as a standalone probe. A future satellite experiment with sufficient sensitivity and resolution to measure the lensed B modes on most of the sky can constrain key parameters of patchy reionization, such as the duration of the patchy epoch or the mean bubble radius, at the {approx}10% level.

  7. Latest inflation model constraints from cosmic microwave background measurements: Addendum

    SciTech Connect

    Kinney, William H.; Kolb, Edward W.; Melchiorri, Alessandro; Riotto, Antonio

    2008-10-15

    In this addendum to Phys. Rev. D 74, 023502 (2006), we present an update of cosmological constraints on single-field inflation in light of the Wilkinson Microwave Ansiotropy Probe satellite mission five-year results (WMAP5). We find that the cosmic microwave background data are quite consistent with a Harrison-Zel'dovich primordial spectrum with no running and zero tensor amplitude. We find that the three main conclusions of our analysis of the WMAP three-year data (WMAP3) are consistent with the WMAP5 data: (1) the Harrison-Zel'dovich model is within the 95% confidence level contours; (2) there is no evidence for running of the spectral index of scalar perturbations; (3) from the WMAP 5 data alone, potentials of the form V{proportional_to}{phi}{sup p} are consistent with the data for p=2 and are ruled out for p=4. Furthermore, consistent with our WMAP3 analysis, we find no evidence for primordial tensor perturbations, this time with a 95% confidence upper limit of r<0.4 for the WMAP5 data alone, and r<0.35 for the WMAP5 data taken in combination with the Arcminute Cosmology Bolometer Array (ACBAR)

  8. Anisotropies in the cosmic microwave background: an analytic approach

    NASA Astrophysics Data System (ADS)

    Hu, Wayne; Sugiyama, Naoshi

    1995-05-01

    We introduce a conceptually simple yet powerful analytic method which traces the structure of cosmic microwave background anisotropies to better than 5%-10% in temperature fluctuations on all scales. It is applicable to any model in which the gravitational potential is known and last scattering is sufficiently early. Moreover, it recovers and explains the presence of the 'Doppler peaks' at degree scales as driven acoustic oscillations of the photon-baryon fluid. We treat in detail such subtleties as the time dependence of the gravitational driving force, anisotropic stress from the neutrino quadrupole, and damping during the recombination process, again all from an analytic standpoint. We apply this formalism to the standard cold dark matter model to gain physical insight into the anisotropies, including the dependence of the peak locations and heights on cosmological parameters such as Omegab and h. Furthermore, the ionization history controls damping due to the finite thickness of the last scattering surface, which is in fact mianly caused by photon diffusion. In addition to being a powerful probe into the nature of anisotropies, this treatment can be used in place of the standard Boltzmann code where 5%-10% accuracy in temperature fluctuations is satisfactory and/or speed is essential. Equally importantly, it can be used as a portable standard by which numerical codes can be tested and compared.

  9. COSMIC MICROWAVE BACKGROUND CONSTRAINTS OF DECAYING DARK MATTER PARTICLE PROPERTIES

    SciTech Connect

    Yeung, S.; Chan, M. H.; Chu, M.-C.

    2012-08-20

    If a component of cosmological dark matter is made up of massive particles-such as sterile neutrinos-that decay with cosmological lifetime to emit photons, the reionization history of the universe would be affected, and cosmic microwave background anisotropies can be used to constrain such a decaying particle model of dark matter. The optical depth depends rather sensitively on the decaying dark matter particle mass m{sub dm}, lifetime {tau}{sub dm}, and the mass fraction of cold dark matter f that they account for in this model. Assuming that there are no other sources of reionization and using the Wilkinson Microwave Anisotropy Probe 7-year data, we find that 250 eV {approx}< m{sub dm} {approx}< 1 MeV, whereas 2.23 Multiplication-Sign 10{sup 3} yr {approx}< {tau}{sub dm}/f {approx}< 1.23 Multiplication-Sign 10{sup 18} yr. The best-fit values for m{sub dm} and {tau}{sub dm}/f are 17.3 keV and 2.03 Multiplication-Sign 10{sup 16} yr, respectively.

  10. New cosmic microwave background constraint to primordial gravitational waves.

    PubMed

    Smith, Tristan L; Pierpaoli, Elena; Kamionkowski, Marc

    2006-07-14

    Primordial gravitational waves (GWs) with frequencies > or approximately equal to 10(-15) Hz contribute to the radiation density of the Universe at the time of decoupling of the cosmic microwave background (CMB). This affects the CMB and matter power spectra in a manner identical to massless neutrinos, unless the initial density perturbation for the GWs is nonadiabatic, as may occur if such GWs are produced during inflation or some post-inflation phase transition. In either case, current observations provide a constraint to the GW amplitude that competes with that from big-bang nucleosynthesis (BBN), although it extends to much lower frequencies (approximately 10(-15) Hz rather than the approximately 10(-10) Hz from BBN): at 95% confidence level, omega(gw)h(2)

  11. COSMIC MICROWAVE BACKGROUND LIKELIHOOD APPROXIMATION FOR BANDED PROBABILITY DISTRIBUTIONS

    SciTech Connect

    Gjerløw, E.; Mikkelsen, K.; Eriksen, H. K.; Næss, S. K.; Seljebotn, D. S.; Górski, K. M.; Huey, G.; Jewell, J. B.; Rocha, G.; Wehus, I. K.

    2013-11-10

    We investigate sets of random variables that can be arranged sequentially such that a given variable only depends conditionally on its immediate predecessor. For such sets, we show that the full joint probability distribution may be expressed exclusively in terms of uni- and bivariate marginals. Under the assumption that the cosmic microwave background (CMB) power spectrum likelihood only exhibits correlations within a banded multipole range, Δl{sub C}, we apply this expression to two outstanding problems in CMB likelihood analysis. First, we derive a statistically well-defined hybrid likelihood estimator, merging two independent (e.g., low- and high-l) likelihoods into a single expression that properly accounts for correlations between the two. Applying this expression to the Wilkinson Microwave Anisotropy Probe (WMAP) likelihood, we verify that the effect of correlations on cosmological parameters in the transition region is negligible in terms of cosmological parameters for WMAP; the largest relative shift seen for any parameter is 0.06σ. However, because this may not hold for other experimental setups (e.g., for different instrumental noise properties or analysis masks), but must rather be verified on a case-by-case basis, we recommend our new hybridization scheme for future experiments for statistical self-consistency reasons. Second, we use the same expression to improve the convergence rate of the Blackwell-Rao likelihood estimator, reducing the required number of Monte Carlo samples by several orders of magnitude, and thereby extend it to high-l applications.

  12. Litmus Test for Cosmic Hemispherical Asymmetry in the Cosmic Microwave Background B -Mode Polarization

    NASA Astrophysics Data System (ADS)

    Mukherjee, Suvodip; Souradeep, Tarun

    2016-06-01

    Recent measurements of the temperature field of the cosmic microwave background (CMB) provide tantalizing evidence for violation of statistical isotropy (SI) that constitutes a fundamental tenet of contemporary cosmology. CMB space based missions, WMAP, and Planck have observed a 7% departure in the SI temperature field at large angular scales. However, due to higher cosmic variance at low multipoles, the significance of this measurement is not expected to improve from any future CMB temperature measurements. We demonstrate that weak lensing of the CMB due to scalar perturbations produces a corresponding SI violation in B modes of CMB polarization at smaller angular scales. The measurability of this phenomenon depends upon the scales (l range) over which power asymmetry is present. Power asymmetry, which is restricted only to l <64 in the temperature field, cannot lead to any significant observable effect from this new window. However, this effect can put an independent bound on the spatial range of scales of hemispherical asymmetry present in the scalar sector.

  13. Non-Gaussianity in the Cosmic Microwave Background temperature fluctuations from cosmic (super-)strings

    SciTech Connect

    Takahashi, Keitaro; Naruko, Atsushi; Sendouda, Yuuiti; Yamauchi, Daisuke; Sasaki, Misao; Yoo, Chul-Moon E-mail: naruko@yukawa.kyoto-u.ac.jp E-mail: yamauchi@yukawa.kyoto-u.ac.jp E-mail: misao@yukawa.kyoto-u.ac.jp

    2009-10-01

    We compute analytically the small-scale temperature fluctuations of the cosmic microwave background from cosmic (super-)strings and study the dependence on the string intercommuting probability P. We develop an analytical model which describes the evolution of a string network and calculate the numbers of string segments and kinks in a horizon volume. Then we derive the probability distribution function (pdf) which takes account of finite angular resolution of observation. The resultant pdf consists of a Gaussian part due to frequent scatterings by long string segments and a non-Gaussian tail due to close encounters with kinks. The dispersion of the Gaussian part is reasonably consistent with that obtained by numerical simulations by Fraisse et al.. On the other hand, the non-Gaussian tail contains two phenomenological parameters which are determined by comparison with the numerical results for P = 1. Extrapolating the pdf to the cases with P < 1, we predict that the non-Gaussian feature is suppressed for small P.

  14. Litmus Test for Cosmic Hemispherical Asymmetry in the Cosmic Microwave Background B-Mode Polarization.

    PubMed

    Mukherjee, Suvodip; Souradeep, Tarun

    2016-06-01

    Recent measurements of the temperature field of the cosmic microwave background (CMB) provide tantalizing evidence for violation of statistical isotropy (SI) that constitutes a fundamental tenet of contemporary cosmology. CMB space based missions, WMAP, and Planck have observed a 7% departure in the SI temperature field at large angular scales. However, due to higher cosmic variance at low multipoles, the significance of this measurement is not expected to improve from any future CMB temperature measurements. We demonstrate that weak lensing of the CMB due to scalar perturbations produces a corresponding SI violation in B modes of CMB polarization at smaller angular scales. The measurability of this phenomenon depends upon the scales (l range) over which power asymmetry is present. Power asymmetry, which is restricted only to l<64 in the temperature field, cannot lead to any significant observable effect from this new window. However, this effect can put an independent bound on the spatial range of scales of hemispherical asymmetry present in the scalar sector. PMID:27314711

  15. Cosmic ray contributions to the WMAP polarization data on the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Wibig, Tadeusz; Wolfendale, Arnold W.

    2016-01-01

    We have updated our analysis of the 9-year WMAP data using the collection of polarization maps looking for the presence of additional evidence for a finite ‘cosmic ray (CR) foreground’ for the cosmic microwave background (CMB). We have given special attention to high Galactic latitudes, where the recent BICEP2 findings were reported although very recent Planck data claims that dust is prevalent, thus nullifying the BICEP2 results. The method of examining the correlation with the observed gamma ray flux proposed in our earlier papers and applied to the polarization data shows that the foreground related to CRs is still observed even at high Galactic latitudes and conclusions about gravitational waves are not yet secure. Theory has it that there is important information about inflationary gravitational waves in the fine structure of the CMB polarization properties (polarization vector and angle) and it is necessary to examine further the conclusions that can be gained from studies of the CMB maps, in view of the disturbing foreground effects.

  16. Polarized cosmic microwave background map recovery with sparse component separation

    NASA Astrophysics Data System (ADS)

    Bobin, J.; Sureau, F.; Starck, J.-L.

    2015-11-01

    The polarization modes of the cosmological microwave background are an invaluable source of information for cosmology and a unique window to probe the energy scale of inflation. Extracting this information from microwave surveys requires distinguishing between foreground emissions and the cosmological signal, which means solving a component separation problem. Component separation techniques have been widely studied for the recovery of cosmic microwave background (CMB) temperature anisotropies, but very rarely for the polarization modes. In this case, most component separation techniques make use of second-order statistics to distinguish between the various components. More recent methods, which instead emphasize the sparsity of the components in the wavelet domain, have been shown to provide low-foreground, full-sky estimates of the CMB temperature anisotropies. Building on sparsity, we here introduce a new component separation technique dubbed the polarized generalized morphological component analysis (PolGMCA), which refines previous work to specifically work on the estimation of the polarized CMB maps: i) it benefits from a recently introduced sparsity-based mechanism to cope with partially correlated components; ii) it builds upon estimator aggregation techniques to further yield a better noise contamination/non-Gaussian foreground residual trade-off. The PolGMCA algorithm is evaluated on simulations of full-sky polarized microwave sky simulations using the Planck Sky Model (PSM). The simulations show that the proposed method achieves a precise recovery of the CMB map in polarization with low-noise and foreground contamination residuals. It provides improvements over standard methods, especially on the Galactic center, where estimating the CMB is challenging.

  17. Cosmic birefringence fluctuations and cosmic microwave background B-mode polarization

    NASA Astrophysics Data System (ADS)

    Lee, Seokcheon; Liu, Guo-Chin; Ng, Kin-Wang

    2015-06-01

    Recently, BICEP2 measurements of the cosmic microwave background (CMB) B-mode polarization has indicated the presence of primordial gravitational waves at degree angular scales, inferring the tensor-to-scalar ratio of r = 0.2 and a running scalar spectral index, provided that dust contamination is low. In this Letter, we show that the existence of the fluctuations of cosmological birefringence can give rise to CMB B-mode polarization that fits BICEP2 data with r < 0.11 and no running of the scalar spectral index. When dust contribution is taken into account, we derive an upper limit on the cosmological birefringence, Aβ2 < 0.0075, where A is the amplitude of birefringence fluctuations that couple to electromagnetism with a coupling strength β.

  18. The Imprint of Patchy Reionization on the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Trac, Hy

    Cosmic reionization is a frontier topic in cosmology with plenty of scientific richness for theoretical and observational explorations. What uniquely marks the epoch of reionization (EoR) is the emergence of the first luminous sources. Studying the EoR will reveal how the first generation of stars, galaxies, and quasars formed and evolved. It can provide constraints on cosmological parameters comparable to studies of the cosmic microwave background (CMB). Over the next few years, CMB observations alone have the potential to provide strong constraints on the EoR. Inhomogeneous electron scattering during the EoR generated secondary temperature fluctuations and induced E-mode polarization in the CMB. The Planck satellite will have much improved full-sky measurements of the temperature and polarization power spectra compared. The Atacama Cosmology Telescope with polarization (ACTPol) and South Pole Telescope with polarization (SPTPol) will complimentarily provide higher resolution and sensitivity measurements over several thousand square degrees. The proposed project will study the imprint of cosmic reionization on the CMB using direct cosmological (radiative transfer + hydrodynamic + N-body) simulations and calibrated semi-analytical models. The complexity of reionization requires high- resolution simulations with better physical models that can be tested against high-redshift observations. To model the observational signatures, faster semi-analytical techniques are required to make large-scale mock observations and to explore the large parameter space. Radiation-hydrodynamic simulations will be run to study how the distribution and properties of radiation sources and sinks affect the detailed history of the EoR. Parametric, semi-analytical models will be used to construct large-scale mock observations. The model parameters will be calibrated against simulations, but are varied away from the fiducial values to explore the parameter space. The imprint of anisotropic

  19. Cosmic background radiation anisotropy in an open inflation, cold dark matter cosmogony

    NASA Technical Reports Server (NTRS)

    Kamionkowski, Marc; Ratra, Bharat; Spergel, David N.; Sugiyama, Naoshi

    1994-01-01

    We compute the cosmic background radiation anisotropy, produced by energy-density fluctuations generated during an early epoch of inflation, in an open cosmological model based on the cold dark matter scenario. At Omega(sub 0) is approximately 0.3-0.4, the Cosmic Background Explorer (COBE) normalized open model appears to be consistent with most observations.

  20. The dark mark of large-scale structure on the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Granett, Benjamin R.

    2010-10-01

    The cosmic microwave background (CMB) offers a screen to study the Universe in projection. Large-scale structures leave gravitational imprints on the background radiation through the integrated Sachs-Wolfe effect. In an accelerating universe, photons following trajectories across large clusters or voids are heated or cooled as the gravitational potential decays. The hot and cold marks left on the radiation field are a direct signature of dark energy in a spatially flat universe. We use the Sloan Digital Sky Survey to trace large-scale structures and confirm their effect on the cosmic microwave background. We construct a map of the anisotropy over the survey area and find that the pattern is present on the microwave sky. This detection demonstrates that the positive statistical correlation between the galaxy density and the CMB temperature reported in the literature is consistent with the integrated Sachs-Wolfe effect under dark energy. The imprints of individual voids and clusters can be isolated on the cosmic microwave background. By summing the signal from voids and clusters, we overcome the noise of primary fluctuations and produce an image of the average imprint left by the gravitational potential of the structures. Intriguingly, the detection level surpasses the all-sky integrated Sachs-Wolfe measurement. We suggest that the technique may be used as a new probe of dark energy. Supervoid and supercluster structures could be responsible for anomalous regions on the microwave background. We introduce the method of constrained realization to identify statistically anomalous regions on the sky. Of particular interest is the Cold Spot which could arise from a supervoid structure at low redshift. To test this idea, we conduct a photometric redshift survey of the region to moderate redshift. However, we find no strong evidence that a large void is responsible.

  1. ON MEASURING THE COSMIC MICROWAVE BACKGROUND TEMPERATURE AT REDSHIFT 0.89

    SciTech Connect

    Sato, M.; Menten, K. M.; Reid, M. J.; Carilli, C. L.

    2013-02-20

    We report on a measurement of the temperature of the cosmic microwave background radiation field, T {sub CMB}, at z = 0.88582 by imaging HC{sub 3}N(3 <- 2) and (5 <- 4) absorption in the foreground galaxy of the gravitationally lens magnified radio source PKS 1830-211 using the Very Long Baseline Array and the phased Very Large Array. Low-resolution imaging of the data yields a value of T {sub rot} = 5.6{sup +2.5} {sub -0.9} K for the rotational temperature, T {sub rot}, which is consistent with the temperature of the cosmic microwave background at the absorber's redshift of 2.73(1 + z) K. However, our high-resolution imaging reveals that the absorption peak position of the foreground gas is offset from the continuum peak position of the synchrotron radiation from PKS 1830-211SW, which indicates that the absorbing cloud is covering only part of the emission from PKS 1830-211, rather than the entire core-jet region. This changes the line-to-continuum ratios, and we find T {sub rot} between 1.1 and 2.5 K, which is lower than the expected value. This shows that previous T {sub rot} measurements could be biased due to unresolved structure.

  2. High Resolution Observations of the Cosmic Microwave Background Radiation

    NASA Astrophysics Data System (ADS)

    Holzapfel, W. L.

    2005-05-01

    The Cosmic Microwave Background (CMB) radiation provides a view of the Universe as it existed 400,000 years after the Big Bang. This snapshot of the early Universe encodes a wealth of information about the constituents of the Universe and perhaps the mechanism of inflation. Observations of primordial CMB temperature fluctuations have played a key role in the development and testing of the emerging standard cosmological model. Recently, the WMAP experiment has produced a map of the CMB over the entire sky with resolution of about 20 arcminutes. Despite this stunning achievement, higher resolution observations of CMB anisotropy continue to play a role in improving constraints on the Dark Matter density and the spectrum of primordial fluctuations from inflation. In addition to being a unique probe of the early Universe, the CMB has the potential to become a powerful tool for studying the growth of structure. As photons travel from the surface of last scattering to our telescopes, they interact with the intervening matter. In particular, these photons can be scattered by hot electrons bound to clusters of galaxies. The resulting spectral distortion, the Sunyeav-Zel'dovich Effect (SZE), has a surface brightness that is independent of redshift and, therefore, provides a way to search for and study distant galaxy clusters. The SZE is a promising probe of the growth of structure and has the potential to place interesting constraints on the Dark Energy equation of state. This ambitious goal requires high resolution and brightness sensitivity surveys over large areas of the sky. In this talk, I will review the state of the field and discuss the potential of the new generation of experiments set to begin observation in the next few years.

  3. Cosmic Microwave Background B-Mode Polarization Experiment POLARBEAR-2

    NASA Astrophysics Data System (ADS)

    Matsumura, Tomotake; Ade, Peter; Akiba, Yoshiki; Aleman, Christopher; Arnold, Kam; Atlas, Matt; Barron, Darcy; Borrill, Julian; Chapman, Scott; Chinone, Yuji; Cukierman, Ari; Dobbs, Matt; Elleflot, Tucker; Errard, Josquin; Fabbian, Giulio; Feng, Guangyuan; Gilbert, Adam; Grainger, William; Halverson, Nils; Hasegawa, Masaya; Hattori, Kaori; Hazumi, Masashi; Holzapfel, William; Hori, Yasuto; Inoue, Yuki; Jaehnig, Greg; Katayama, Nobuhiko; Keating, Brian; Kermish, Zigmund; Keskitalo, Reijo; Kisner, Ted; Lee, Adrian; Matsuda, Frederick; Morii, Hideki; Moyerman, Stephanie; Myers, Michael; Navaroli, Marty; Nishino, Haruki; Okamura, Takahiro; Reichart, Christian; Richards, Paul; Ross, Colin; Rotermund, Kaja; Sholl, Michael; Siritanasak, Praween; Smecher, Graeme; Stebor, Nathan; Stompor, Radek; Suzuki, Jun-ichi; Suzuki, Aritoki; Takada, Suguru; Takakura, Satoru; Tomaru, Takayuki; Wilson, Brandon; Yamaguchi, Hiroshi; Zahn, Oliver

    POLARBEAR-2 (PB-2) is a ground-based experiment to measure the polarization of the cosmic microwave background (CMB) located at the Atacama desert (5200 m in altitude) in Chile. The science goals of the POLARBEAR-2 are i) to detect or set an upper limit of the inflationary gravitational wave B-mode with the sensitivity of r = 0.01 with 95% C.L. and ii) to measure the weak gravitational lensing B-mode signal and extract the information, such as the sum of neutrino masses with the limit of 90 meV by PB-2 alone and 65 meV by combining PB-2 and Planck at 68% CL. PB-2 observes at the 95 and 150 GHz bands simultaneously using the dichroic dual-polarization antenna-coupled transition edge sensor bolometers together with SQUIDs and the frequency domain multiplexing readout system. The total number of the detectors with the two bands are 7855 that are 6 times more than that of POLARBEAR-1, and the expected focal plane combined statistical sensitivity is 5.7 µK√s with the beam size of 5.2 and3.5 arcmin for the 95 and 150 GHz bands, respectively. The polarization signal is modulated by the sky rotation and the continuously rotating half-wave plate. PB-2 is scheduled to deploy in 2014. The PB-2 receiver will be mounted on the new telescope, which has the same design as the Huan Tran telescope (HTT). We present the overview of PB-2 and discuss the project status.

  4. SELF-CALIBRATION OF COSMIC MICROWAVE BACKGROUND POLARIZATION EXPERIMENTS

    SciTech Connect

    Keating, Brian G.; Yadav, Amit P. S.; Shimon, Meir

    2013-01-10

    Precision measurements of the polarization of the cosmic microwave background (CMB) radiation, especially experiments seeking to detect the odd-parity 'B-modes', have far-reaching implications for cosmology. To detect the B-modes generated during inflation, the flux response and polarization angle of these experiments must be calibrated to exquisite precision. While suitable flux calibration sources abound, polarization angle calibrators are deficient in many respects. Man-made polarized sources are often not located in the antenna's far-field, have spectral properties that are radically different from the CMB's, are cumbersome to implement, and may be inherently unstable over the (long) duration these searches require to detect the faint signature of the inflationary epoch. Astrophysical sources suffer from time, frequency, and spatial variability, are not visible from all CMB observatories, and none are understood with sufficient accuracy to calibrate future CMB polarimeters seeking to probe inflationary energy scales of 10{sup 15} GeV. Both man-made and astrophysical sources require dedicated observations which detract from the amount of integration time usable for detection of the inflationary B-modes. CMB TB and EB modes, expected to identically vanish in the standard cosmological model, can be used to calibrate CMB polarimeters. By enforcing the observed EB and TB power spectra to be consistent with zero, CMB polarimeters can be calibrated to levels not possible with man-made or astrophysical sources. All of this can be accomplished for any polarimeter without any loss of observing time using a calibration source which is spectrally identical to the CMB B-modes.

  5. Imprints of relic gravitational waves in cosmic microwave background radiation

    NASA Astrophysics Data System (ADS)

    Baskaran, D.; Grishchuk, L. P.; Polnarev, A. G.

    2006-10-01

    A strong variable gravitational field of the very early Universe inevitably generates relic gravitational waves by amplifying their zero-point quantum oscillations. We begin our discussion by contrasting the concepts of relic gravitational waves and inflationary “tensor modes”. We explain and summarize the properties of relic gravitational waves that are needed to derive their effects on cosmic microwave background (CMB) temperature and polarization anisotropies. The radiation field is characterized by four invariants I, V, E, B. We reduce the radiative transfer equations to a single integral equation of Voltairre type and solve it analytically and numerically. We formulate the correlation functions CℓXX' for X, X'=T, E, B and derive their amplitudes, shapes and oscillatory features. Although all of our main conclusions are supported by exact numerical calculations, we obtain them, in effect, analytically by developing and using accurate approximations. We show that the TE correlation at lower ℓ’s must be negative (i.e. an anticorrelation), if it is caused by gravitational waves, and positive if it is caused by density perturbations. This difference in TE correlation may be a signature more valuable observationally than the lack or presence of the BB correlation, since the TE signal is about 100 times stronger than the expected BB signal. We discuss the detection by WMAP of the TE anticorrelation at ℓ≈30 and show that such an anticorrelation is possible only in the presence of a significant amount of relic gravitational waves (within the framework of all other common assumptions). We propose models containing considerable amounts of relic gravitational waves that are consistent with the measured TT, TE and EE correlations.

  6. THE COSMIC NEAR-INFRARED BACKGROUND. II. FLUCTUATIONS

    SciTech Connect

    Fernandez, Elizabeth R.; Komatsu, Eiichiro; Shapiro, Paul R.; Iliev, Ilian T.

    2010-02-20

    regarding the nature of sources contributing to the cosmic reionization. The angular power spectrum of the IGM, in most cases, is much smaller than the halo angular power spectrum, except when f{sub esc} is close to unity, t{sub SF} is longer, or the minimum redshift at which the star formation is occurring is high. In addition, low levels of the observed mean background intensity tend to rule out high values of f{sub *} {approx}> 0.2.

  7. Cosmology from secondary anisotropies of the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Sherwin, Blake Daniel

    Gravitational lensing and the Sunyaev-Zel'dovich effect introduce new intensity fluctuations, known as secondary anisotropies, into the cosmic microwave background radiation (CMB). These CMB secondary anisotropies encode a wealth of information about the distribution of dark matter and gas throughout our universe. In this thesis, we present novel measurements of CMB lensing and the Sunyaev-Zel'dovich effect in the microwave background and use them to place new constraints on cosmology. In an early thesis chapter, we describe the first detection of the power spectrum of gravitational lensing of the CMB. The power spectrum is detected at a four sigma significance through a measurement of the four-point correlation function of Atacama Cosmology Telescope (ACT) CMB temperature maps. This first detection gravitationally probes the amplitude of large-scale structure at redshifts ≈ 1 -- 3 to 12% accuracy, and lies at the beginning of an exciting new field of science with the lensing power spectrum. From this measurement of the CMB lensing power spectrum we extract first cosmological constraints. We explain in detail how the amount of dark energy in our universe affects the amplitude of the lensing signal by modifying both the geometry of the universe and the growth of structure. We then demonstrate that our lensing measurements provide, for the first time, evidence for the existence of dark energy from the CMB alone, at a 3.2 sigma significance. We use CMB lensing measurements to study the relation of quasars to the underlying distribution of dark matter. Detecting the cross-power of CMB lensing with the spatial distribution of quasars and hence measuring the quasar bias to within 25%, we obtain a measurement of the characteristic dark matter halo mass of these objects. CMB lensing power spectrum measurements typically require the subtraction of a simulated bias term, which complicates the analysis; we develop new techniques to obviate this bias subtraction. Finally, we

  8. New Constraints on Cosmic Polarization Rotation from B-Mode Polarization in the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    di Serego Alighieri, Sperello; Ni, Wei-Tou; Pan, Wei-Ping

    2014-09-01

    SPTpol, POLARBEAR, and BICEP2 have recently measured the cosmic microwave background (CMB) B-mode polarization in various sky regions of several tens of square degrees and obtained BB power spectra in the multipole range 20-3000, detecting the components due to gravitational lensing and to inflationary gravitational waves. We analyze jointly the results of these three experiments and propose modifications to their analyses of the spectra to include in the model, in addition to the gravitational lensing and the inflationary gravitational wave components, and also the effects induced by the cosmic polarization rotation (CPR), if it exists within current upper limits. Although in principle our analysis would also lead to new constraints on CPR, in practice these can only be given on its fluctuations langδα2rang, since constraints on its mean angle are inhibited by the derotation which is applied by current CMB polarization experiments, in order to cope with the insufficient calibration of the polarization angle. The combined data fits from all three experiments (with 29% CPR-SPTpol correlation, depending on the theoretical model) gives the constraint langδα2rang1/2 < 27.3 mrad (1.°56), with r = 0.194 ± 0.033. These results show that the present data are consistent with no CPR detection and the constraint on CPR fluctuation is about 1.°5. This method of constraining the CPR is new, is complementary to previous tests, which use the radio and optical/UV polarization of radio galaxies and the CMB E-mode polarization, and adds a new constraint for the sky areas observed by SPTpol, POLARBEAR, and BICEP2.

  9. New constraints on cosmic polarization rotation from B-mode polarization in the cosmic microwave background

    SciTech Connect

    Alighieri, Sperello di Serego; Ni, Wei-Tou; Pan, Wei-Ping E-mail: weitou@gmail.com

    2014-09-01

    SPTpol, POLARBEAR, and BICEP2 have recently measured the cosmic microwave background (CMB) B-mode polarization in various sky regions of several tens of square degrees and obtained BB power spectra in the multipole range 20-3000, detecting the components due to gravitational lensing and to inflationary gravitational waves. We analyze jointly the results of these three experiments and propose modifications to their analyses of the spectra to include in the model, in addition to the gravitational lensing and the inflationary gravitational wave components, and also the effects induced by the cosmic polarization rotation (CPR), if it exists within current upper limits. Although in principle our analysis would also lead to new constraints on CPR, in practice these can only be given on its fluctuations (δα{sup 2}), since constraints on its mean angle are inhibited by the derotation which is applied by current CMB polarization experiments, in order to cope with the insufficient calibration of the polarization angle. The combined data fits from all three experiments (with 29% CPR-SPTpol correlation, depending on the theoretical model) gives the constraint (δα{sup 2}){sup 1/2} < 27.3 mrad (1.°56), with r = 0.194 ± 0.033. These results show that the present data are consistent with no CPR detection and the constraint on CPR fluctuation is about 1.°5. This method of constraining the CPR is new, is complementary to previous tests, which use the radio and optical/UV polarization of radio galaxies and the CMB E-mode polarization, and adds a new constraint for the sky areas observed by SPTpol, POLARBEAR, and BICEP2.

  10. THE COSMIC INFRARED BACKGROUND EXPERIMENT (CIBER): A SOUNDING ROCKET PAYLOAD TO STUDY THE NEAR INFRARED EXTRAGALACTIC BACKGROUND LIGHT

    SciTech Connect

    Zemcov, M.; Bock, J.; Hristov, V.; Levenson, L. R.; Mason, P.; Arai, T.; Matsumoto, T.; Matsuura, S.; Tsumura, K.; Wada, T.; Battle, J.; Cooray, A.; Keating, B.; Renbarger, T.; Kim, M. G.; Lee, D. H.; Nam, U. W.; Sullivan, I.; Suzuki, K.

    2013-08-15

    The Cosmic Infrared Background Experiment (CIBER) is a suite of four instruments designed to study the near infrared (IR) background light from above the Earth's atmosphere. The instrument package comprises two imaging telescopes designed to characterize spatial anisotropy in the extragalactic IR background caused by cosmological structure during the epoch of reionization, a low resolution spectrometer to measure the absolute spectrum of the extragalactic IR background, and a narrow band spectrometer optimized to measure the absolute brightness of the zodiacal light foreground. In this paper we describe the design and characterization of the CIBER payload. The detailed mechanical, cryogenic, and electrical design of the system are presented, including all system components common to the four instruments. We present the methods and equipment used to characterize the instruments before and after flight, and give a detailed description of CIBER's flight profile and configurations. CIBER is designed to be recoverable and has flown four times, with modifications to the payload having been informed by analysis of the first flight data. All four instruments performed to specifications during the subsequent flights, and the scientific data from these flights are currently being analyzed.

  11. Multichroic Bolometric Detector Architecture for Cosmic Microwave Background Polarimetry Experiments

    NASA Astrophysics Data System (ADS)

    Suzuki, Aritoki

    Characterization of the Cosmic Microwave Background (CMB) B-mode polarization signal will test models of inflationary cosmology, as well as constrain the sum of the neutrino masses and other cosmological parameters. The low intensity of the B-mode signal combined with the need to remove polarized galactic foregrounds requires a sensitive millimeter receiver and effective methods of foreground removal. Current bolometric detector technology is reaching the sensitivity limit set by the CMB photon noise. Thus, we need to increase the optical throughput to increase an experiment's sensitivity. To increase the throughput without increasing the focal plane size, we can increase the frequency coverage of each pixel. Increased frequency coverage per pixel has additional advantage that we can split the signal into frequency bands to obtain spectral information. The detection of multiple frequency bands allows for removal of the polarized foreground emission from synchrotron radiation and thermal dust emission, by utilizing its spectral dependence. Traditionally, spectral information has been captured with a multi-chroic focal plane consisting of a heterogeneous mix of single-color pixels. To maximize the efficiency of the focal plane area, we developed a multi-chroic pixel. This increases the number of pixels per frequency with same focal plane area. We developed multi-chroic antenna-coupled transition edge sensor (TES) detector array for the CMB polarimetry. In each pixel, a silicon lens-coupled dual polarized sinuous antenna collects light over a two-octave frequency band. The antenna couples the broadband millimeter wave signal into microstrip transmission lines, and on-chip filter banks split the broadband signal into several frequency bands. Separate TES bolometers detect the power in each frequency band and linear polarization. We will describe the design and performance of these devices and present optical data taken with prototype pixels and detector arrays. Our

  12. Non-linear evolution of the cosmic neutrino background

    SciTech Connect

    Villaescusa-Navarro, Francisco; Viel, Matteo; Peña-Garay, Carlos E-mail: spb@ias.edu E-mail: viel@oats.inaf.it

    2013-03-01

    We investigate the non-linear evolution of the relic cosmic neutrino background by running large box-size, high resolution N-body simulations which incorporate cold dark matter (CDM) and neutrinos as independent particle species. Our set of simulations explore the properties of neutrinos in a reference ΛCDM model with total neutrino masses between 0.05-0.60 eV in cold dark matter haloes of mass 10{sup 11}−10{sup 15} h{sup −1}M{sub s}un, over a redshift range z = 0−2. We compute the halo mass function and show that it is reasonably well fitted by the Sheth-Tormen formula, once the neutrino contribution to the total matter is removed. More importantly, we focus on the CDM and neutrino properties of the density and peculiar velocity fields in the cosmological volume, inside and in the outskirts of virialized haloes. The dynamical state of the neutrino particles depends strongly on their momentum: whereas neutrinos in the low velocity tail behave similarly to CDM particles, neutrinos in the high velocity tail are not affected by the clustering of the underlying CDM component. We find that the neutrino (linear) unperturbed momentum distribution is modified and mass and redshift dependent deviations from the expected Fermi-Dirac distribution are in place both in the cosmological volume and inside haloes. The neutrino density profiles around virialized haloes have been carefully investigated and a simple fitting formula is provided. The neutrino profile, unlike the cold dark matter one, is found to be cored with core size and central density that depend on the neutrino mass, redshift and mass of the halo, for halos of masses larger than ∼ 10{sup 13.5}h{sup −1}M{sub s}un. For lower masses the neutrino profile is best fitted by a simple power-law relation in the range probed by the simulations. The results we obtain are numerically converged in terms of neutrino profiles at the 10% level for scales above ∼ 200 h{sup −1}kpc at z = 0, and are stable with

  13. Degree Scale Anisotropy Measurements of the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Gundersen, Joshua Ott

    1995-01-01

    Humans have inquired about the origin, evolution, and content of the Universe for as long as history has been recorded. These paths of inquiry have only just recently evolved from the realm of philosophy and metaphysics into the very quantitative and predictive science of cosmology. This transition has been facilitated by the wealth of observational data in the last three decades. Although we have made large strides in our understanding of the Universe, there are many outstanding questions that have not been precisely answered. Some of these include, "How old is the Universe?", "What is the matter/energy content of the Universe?", Will the Universe continue to expand, or will it one day begin to collapse?", "How did the large scale structures (such as galaxies and clusters of galaxies) first form?". Over the past six years, detailed observations of the cosmic microwave background (CMB) have begun to constrain cosmological models which address these very questions. In particular, measurements of the spatial distribution (anisotropy) of the CMB have been shown to be very powerful tests of theories that attempt to explain the origin, evolution, contents and geometry of the Universe. The subject of this thesis is the search and characterization of medium angular scale anisotropy in the CMB. The scientific motivation for observing CMB anisotropy is presented within a general introduction to our current understanding of the Universe. An overview of the technological and observational hurdles that make CMB anisotropy measurements difficult is given. The main body of the text describes two experimental efforts to measure CMB anisotropy on medium angular scales. The first of these efforts is the Millimeter-wave Anisotropy eXperiment (MAX) which is a balloon-borne telescope that has been developed to measure CMB anisotropy. The second of these efforts involves ground-based observations of CMB anisotropy from the Amundsen-Scott South Pole station. Both of these efforts have

  14. MEASUREMENT OF COSMIC MICROWAVE BACKGROUND POLARIZATION POWER SPECTRA FROM TWO YEARS OF BICEP DATA

    SciTech Connect

    Chiang, H. C.; Barkats, D.; Bock, J. J.; Hristov, V. V.; Jones, W. C.; Kovac, J. M.; Lange, A. E.; Mason, P. V.; Matsumura, T.; Ade, P. A. R.; Battle, J. O.; Dowell, C. D.; Nguyen, H. T.; Bierman, E. M.; Keating, B. G.; Duband, L.; Hivon, E. F.; Holzapfel, W. L.; Kuo, C. L.; Leitch, E. M.

    2010-03-10

    Background Imaging of Cosmic Extragalactic Polarization (BICEP) is a bolometric polarimeter designed to measure the inflationary B-mode polarization of the cosmic microwave background (CMB) at degree angular scales. During three seasons of observing at the South Pole (2006 through 2008), BICEP mapped {approx}2% of the sky chosen to be uniquely clean of polarized foreground emission. Here, we present initial results derived from a subset of the data acquired during the first two years. We present maps of temperature, Stokes Q and U, E and B modes, and associated angular power spectra. We demonstrate that the polarization data are self-consistent by performing a series of jackknife tests. We study potential systematic errors in detail and show that they are sub-dominant to the statistical errors. We measure the E-mode angular power spectrum with high precision at 21 <= l <= 335, detecting for the first time the peak expected at l {approx} 140. The measured E-mode spectrum is consistent with expectations from a LAMBDACDM model, and the B-mode spectrum is consistent with zero. The tensor-to-scalar ratio derived from the B-mode spectrum is r = 0.02{sup +0.31}{sub -0.26}, or r < 0.72 at 95% confidence, the first meaningful constraint on the inflationary gravitational wave background to come directly from CMB B-mode polarization.

  15. MCNP6 Cosmic & Terrestrial Background Particle Fluxes -- Release 4

    SciTech Connect

    McMath, Garrett E.; McKinney, Gregg W.; Wilcox, Trevor

    2015-01-23

    Essentially a set of slides, the presentation begins with the MCNP6 cosmic-source option, then continues with the MCNP6 transport model (atmospheric, terrestrial) and elevation scaling. It concludes with a few slides on results, conclusions, and suggestions for future work.

  16. Gravitational-wave stochastic background from kinks and cusps on cosmic strings

    SciTech Connect

    Oelmez, S.; Mandic, V.; Siemens, X.

    2010-05-15

    We compute the contribution of kinks on cosmic string loops to stochastic background of gravitational waves (SBGW). We find that kinks contribute at the same order as cusps to the SBGW. We discuss the accessibility of the total background due to kinks as well as cusps to current and planned gravitational-wave detectors, as well as to the big bang nucleosynthesis (BBN), the cosmic microwave background (CMB), and pulsar timing constraints. As in the case of cusps, we find that current data from interferometric gravitational-wave detectors, such as LIGO, are sensitive to areas of parameter space of cosmic string models complementary to those accessible to pulsar, BBN, and CMB bounds.

  17. On the effect of cosmic rays in bolometric cosmic microwave background measurements from the stratosphere

    NASA Astrophysics Data System (ADS)

    Masi, S.; Battistelli, E.; de Bernardis, P.; Lamagna, L.; Nati, F.; Nati, L.; Natoli, P.; Polenta, G.; Schillaci, A.

    2010-09-01

    Context. Precision measurements of the anisotropy of the cosmic microwave background (CMB) are able to detect low-level non-Gaussian features caused by either topological defects or the inflation process. These measurements are becoming feasable with the development of large arrays of ultra-sensitive bolometric detectors and their use in balloon-borne or satellite missions. However, the space environment includes a population of cosmic rays (CRs), which produce spurious spikes in bolometric signals. Aims: We analyze the effect of CRs on the measurement of CMB anisotropy maps and the estimate of cosmological non-Gaussianity and angular power spectra of the CMB. Methods: Using accurate simulations of noise and CR events in bolometric detectors, and de-spiking techniques, we produce simulated measured maps and analyze the Gaussianity and power spectrum of the maps for different levels and rates of CR events. Results: We find that a de-spiking technique based on outlier removal in the detector signals contributing to the same sky pixel is effective in removing CR events larger than the noise. However, low level events hidden in the noise produce a positive shift of the average power signal measured by a bolometer, and increase its variance. If the number of hits per pixel is large enough, the data distribution for each sky pixel is approximately Gaussian, but the skewness and the kurtosis of the temperatures of the pixels indicate the presence of some low-level non-Gaussianity. The standard noise estimation pipeline produces a positive bias in the power spectrum at high multipoles. Conclusions: In the case of a typical balloon-borne survey, the CR-induced non-Gaussianity will be marginally detectable in the membrane bolometer channels, but be negligible in the spider-web bolometer channels. In experiments with detector sensitivity better than 100 μK/√{Hz}, in an environment less favorable than the earth stratosphere, the CR-induced non-Gaussianity is likely to

  18. CHARACTERIZATION OF THE BICEP TELESCOPE FOR HIGH-PRECISION COSMIC MICROWAVE BACKGROUND POLARIMETRY

    SciTech Connect

    Takahashi, Y. D.; Holzapfel, W. L.; Ade, P. A. R.; Barkats, D.; Bock, J. J.; Chiang, H. C.; Hristov, V. V.; Jones, W. C.; Kovac, J. M.; Lange, A. E.; Mason, P. V.; Matsumura, T.; Battle, J. O.; Dowell, C. D.; Bierman, E. M.; Keating, B. G.; Duband, L.; Hivon, E. F.; Kuo, C. L.; Leitch, E. M.

    2010-03-10

    The Background Imaging of Cosmic Extragalactic Polarization (BICEP) experiment was designed specifically to search for the signature of inflationary gravitational waves in the polarization of the cosmic microwave background (CMB). Using a novel small-aperture refractor and 49 pairs of polarization-sensitive bolometers, BICEP has completed three years of successful observations at the South Pole beginning in 2006 February. To constrain the amplitude of the inflationary B-mode polarization, which is expected to be at least 7 orders of magnitude fainter than the 3 K CMB intensity, precise control of systematic effects is essential. This paper describes the characterization of potential systematic errors for the BICEP experiment, supplementing a companion paper on the initial cosmological results. Using the analysis pipelines for the experiment, we have simulated the impact of systematic errors on the B-mode polarization measurement. Guided by these simulations, we have established benchmarks for the characterization of critical instrumental properties including bolometer relative gains, beam mismatch, polarization orientation, telescope pointing, sidelobes, thermal stability, and timestream noise model. A comparison of the benchmarks with the measured values shows that we have characterized the instrument adequately to ensure that systematic errors do not limit BICEP's two-year results, and identifies which future refinements are likely necessary to probe inflationary B-mode polarization down to levels below a tensor-to-scalar ratio r = 0.1.

  19. Color gradient background oriented schlieren imaging

    NASA Astrophysics Data System (ADS)

    Mier, Frank Austin; Hargather, Michael

    2015-11-01

    Background oriented schlieren (BOS) imaging is a method of visualizing refractive disturbances through the comparison of digital images. By comparing images with and without a refractive disturbance visualizations can be achieved via a range of image processing methods. Traditionally, backgrounds consist of random distributions of high contrast speckle patterns. To image a refractive disturbance, a digital image correlation algorithm is used to identify the location and magnitude of apparent pixel shifts in the background pattern. Here a novel method of using color gradient backgrounds is explored as an alternative. The gradient background eliminates the need to perform an image correlation between the two digital images, as simple image subtraction can be used to identify the location, magnitude, and direction of the image distortions. This allows for quicker processing. Two-dimensional gradient backgrounds using multiple colors are shown. The gradient backgrounds are demonstrated to provide quantitative data limited only by the camera's pixel resolution, whereas speckle backgrounds limit resolution to the size of the random pattern features and image correlation window size. Additional results include the use of a computer screen as a background.

  20. Summary of the Workshop on Ultraviolet Cosmic Background Radiation

    NASA Technical Reports Server (NTRS)

    Henry, R. C.

    1981-01-01

    The relationship of the ultraviolet background radiation to the X-ray background is shown. The ultraviolet background, which is four orders of magnitude brighter than the x-ray background, is much less well determined. The relationship of the ultraviolet background to the EUV background and an excellent summary of the discordant ultraviolet observations at high galactic latitudes are given. A picture of the universe from the point of view of those who study ultraviolet background radiation, with emphasis on the various sources of noise that can affect the measurements is presented. The altitudes of various observing platforms are also indicated.

  1. STREAMING COLD COSMIC-RAY BACK-REACTION AND THERMAL INSTABILITIES ALONG THE BACKGROUND MAGNETIC FIELD

    SciTech Connect

    Nekrasov, Anatoly K.; Shadmehri, Mohsen E-mail: nekrasov.anatoly@gmail.com

    2012-09-01

    Using a multi-fluid approach, we investigate the streaming and thermal instabilities of electron-ion-cosmic-ray astrophysical objects in which homogeneous cold cosmic rays have a drift velocity perpendicular to the background magnetic field. One-dimensional perturbations along the magnetic field are considered. The induced return current of the background plasma and back-reaction of cosmic rays are taken into account. It is shown that the cosmic-ray back-reaction results in a streaming instability with considerably higher growth rates than that due to the return current of the background plasma. This increase is by a factor of the square root of the ratio of the background plasma mass density to the cosmic-ray mass density. The maximal growth rate and the corresponding wavenumber are then found. Thermal instability is shown to be not subject to the action of cosmic rays in the model under consideration. The dispersion relation for thermal instability includes ion inertia. In the limit of a fast thermal energy exchange between electrons and ions, the isobaric and isochoric growth rates are obtained. The results can be useful for the investigation of electron-ion astrophysical objects such as galaxy clusters, including the dynamics of streaming cosmic rays.

  2. Imprints of cosmic strings on the cosmological gravitational wave background

    SciTech Connect

    Kleidis, K; Papadopoulos, D B; Vlahos, L; Verdaguer, E

    2008-07-15

    The equation which governs the temporal evolution of a gravitational wave (GW) in curved space-time can be treated as the Schroedinger equation for a particle moving in the presence of an effective potential. When GWs propagate in an expanding universe with constant effective potential, there is a critical value (k{sub c}) of the comoving wave number which discriminates the metric perturbations into oscillating (k>k{sub c}) and nonoscillating (kcosmic strings (subdominant). It is known that the cosmological evolution gradually results in the scaling of a cosmic-string network and, therefore, after some time ({delta}{tau}) the Universe becomes radiation dominated. The evolution of the nonoscillatory GW modes during {delta}{tau} (while they were outside the horizon), results in the distortion of the GW power spectrum from what it is anticipated in a pure radiation model, at present-time frequencies in the range 10{sup -16} Hz

  3. Color gradient background-oriented schlieren imaging

    NASA Astrophysics Data System (ADS)

    Mier, Frank Austin; Hargather, Michael J.

    2016-06-01

    Background-oriented schlieren is a method of visualizing refractive disturbances by comparing digital images with and without a refractive disturbance distorting a background pattern. Traditionally, backgrounds consist of random distributions of high-contrast color transitions or speckle patterns. To image a refractive disturbance, a digital image correlation algorithm is used to identify the location and magnitude of apparent pixel shifts in the background pattern between the two images. Here, a novel method of using color gradient backgrounds is explored as an alternative that eliminates the need to perform a complex image correlation between the digital images. A simple image subtraction can be used instead to identify the location, magnitude, and direction of the image distortions. Gradient backgrounds are demonstrated to provide quantitative data only limited by the camera's pixel resolution, whereas speckle backgrounds limit resolution to the size of the random pattern features and image correlation window size. Quantitative measurement of density in a thermal boundary layer is presented. Two-dimensional gradient backgrounds using multiple colors are demonstrated to allow measurement of two-dimensional refractions. A computer screen is used as the background, which allows for rapid modification of the gradient to tune sensitivity for a particular application.

  4. Lower Bound on the Cosmic TeV Gamma-Ray Background Radiation

    NASA Astrophysics Data System (ADS)

    Inoue, Yoshiyuki; Tanaka, Yasuyuki T.

    2016-02-01

    The Fermi gamma-ray space telescope has revolutionized our understanding of the cosmic gamma-ray background radiation in the GeV band. However, investigation on the cosmic TeV gamma-ray background radiation still remains sparse. Here, we report the lower bound on the cosmic TeV gamma-ray background spectrum placed by the cumulative flux of individual detected extragalactic TeV sources including blazars, radio galaxies, and starburst galaxies. The current limit on the cosmic TeV gamma-ray background above 0.1 TeV is obtained as 2.8 × 10-8(E/100 GeV)-0.55 exp(-E/2100GeV)[GeV cm-2 s-1 sr-1] < E2dN/dE < 1.1 × 10-7(E/100 GeV)-0.49 [GeV cm-2 s-1 sr-1], where the upper bound is set by requirement that the cascade flux from the cosmic TeV gamma-ray background radiation can not exceed the measured cosmic GeV gamma-ray background spectrum. Two nearby blazars, Mrk 421 and Mrk 501, explain ˜70% of the cumulative background flux at 0.8-4 TeV, while extreme blazars start to dominate at higher energies. We also provide the cumulative background flux from each population, i.e., blazars, radio galaxies, and starburst galaxies which will be the minimum requirement for their contribution to the cosmic TeV gamma-ray background radiation.

  5. Pip Analysis of the Cosmic Microwave Background Data - Application to the Tenerife Experiment

    NASA Astrophysics Data System (ADS)

    Gutierrez de La Cruz, C. M.; Martinez-Gonzalez, E.; Cayon, L.; Rebolo, R.; Sanz, J. L.

    1994-12-01

    We present two geometrical methods to analyse the cosmic microwave background data along a strip in the sky. These methods are motivated by the fact that the temperature fluctuation field, on large angular scales, is not ergodic on the cosmic photosphere. This property is examined in the context of different experimental configurations. The methods involve a numerical study of the expected pip number and distribution function of pip sizes, and take into account the non-ergodicity of the temperature field. They are applied to the new measurements of the Tenerife experiment, assuming a Gaussian random field for the temperature fluctuations with power spectra poc k in a flat universe. Moreover, these geometrical methods can be readily used to test non-Gaussian random fields as representations of the cosmic microwave background temperature fluctuations. Key words: methods: data analysis - cosmic microwave background - cosmology: observations.

  6. Image segmentation by background extraction refinements

    NASA Technical Reports Server (NTRS)

    Rodriguez, Arturo A.; Mitchell, O. Robert

    1990-01-01

    An image segmentation method refining background extraction in two phases is presented. In the first phase, the method detects homogeneous-background blocks and estimates the local background to be extracted throughout the image. A block is classified homogeneous if its left and right standard deviations are small. The second phase of the method refines background extraction in nonhomogeneous blocks by recomputing the shoulder thresholds. Rules that predict the final background extraction are derived by observing the behavior of successive background statistical measurements in the regions under the presence of dark and/or bright object pixels. Good results are shown for a number of outdoor scenes.

  7. SurveillanceRadiographic imaging with cosmic-ray muons

    NASA Astrophysics Data System (ADS)

    Borozdin, Konstantin N.; Hogan, Gary E.; Morris, Christopher; Priedhorsky, William C.; Saunders, Alexander; Schultz, Larry J.; Teasdale, Margaret E.

    2003-03-01

    Despite its enormous success, X-ray radiography has its limitations: an inability to penetrate dense objects, the need for multiple projections to resolve three-dimensional structure, and health risks from radiation. Here we show that natural background muons, which are generated by cosmic rays and are highly penetrating, can be used for radiographic imaging of medium-to-large, dense objects, without these limitations and with a reasonably short exposure time. This inexpensive and harmless technique may offer a useful alternative for detecting dense materials - for example, a block of uranium concealed inside a truck full of sheep.

  8. The Cosmic Microwave Background: Detection and Interpretation of the First Light

    NASA Technical Reports Server (NTRS)

    Wollack, Edward J.

    2016-01-01

    A host of astrophysical observations suggest the early Universe was incredibly hot, dense, and homogeneous. A powerful and useful probe of this epoch is provided by the relic radiation, which we refer to today as the Cosmic Microwave Background (CMB). Precision maps of this light contain the earliest glimpse of the Universe after the Big Bang and signatures of the evolution of its contents. By exploiting these clues, constraints on the age, mass density, detailed composition, and geometry of the Universe can be made. A brief survey of the evolution of the radiometric and polarimetric imaging systems used in advancing our understanding of the early Universe will be reviewed. A survey of detector technologies, instrumentation techniques, and experimental challenges encountered in these efforts will be presented.

  9. BAYESIAN INFERENCE OF POLARIZED COSMIC MICROWAVE BACKGROUND POWER SPECTRA FROM INTERFEROMETRIC DATA

    SciTech Connect

    Karakci, Ata; Korotkov, Andrei; Tucker, Gregory S.; Sutter, P. M.; Wandelt, Benjamin D.; Zhang, Le; Timbie, Peter; Bunn, Emory F.

    2013-01-15

    Detection of B-mode polarization of the cosmic microwave background (CMB) radiation is one of the frontiers of observational cosmology. Because they are an order of magnitude fainter than E-modes, it is quite a challenge to detect B-modes. Having more manageable systematics, interferometers prove to have a substantial advantage over imagers in detecting such faint signals. Here, we present a method for Bayesian inference of power spectra and signal reconstruction from interferometric data of the CMB polarization signal by using the technique of Gibbs sampling. We demonstrate the validity of the method in the flat-sky approximation for a simulation of an interferometric observation on a finite patch with incomplete uv-plane coverage, a finite beam size, and a realistic noise model. With a computational complexity of O(n {sup 3/2}), n being the data size, Gibbs sampling provides an efficient method for analyzing upcoming cosmology observations.

  10. Progress in understanding the diffuse UV cosmic background

    NASA Astrophysics Data System (ADS)

    Henry, Richard Conn

    I report on progress in my ongoing work with Professor Jayant Murthy concerning the origin and nature of the diffuse ultraviolet background radiation over the sky. We have obtained and are reducing a vast trove of Voyager ultraviolet spectrometer observations of the diffuse background shortward of Lalpha , including for the first time measurements made from the outermost regions of the solar system, where noise from solar-system scattered (and then grating-scattered) solar Lalpha is lowest. Also, we have obtained and are investigating the complete set of GALEX observations of the diffuse ultraviolet background longward of Lalpha . Preliminary investigation appears to confirm that longward of Lalpha there exists a component of the diffuse ultraviolet background that is not dust-scattered starlight.

  11. Cosmic far ultraviolet background. [observations for intergalactic medium properties

    NASA Technical Reports Server (NTRS)

    Davidsen, A.; Bowyer, S.; Lampton, M.

    1974-01-01

    The expected intensities of various possible components of the far ultraviolet background are discussed. It is concluded that existing results do not place interesting constraints on the density of the intergalactic medium (IGM). Current techniques and instrumentation for far ultraviolet astronomy are, however, sufficient to achieve vastly improved limits. New observations are required to determine whether the IGM can be detected in the far ultraviolet or whether the extragalactic component of the background is masked by radiation with a more local origin.

  12. Propagation of Polarized Cosmic Microwave Background Radiation in an Anisotropic Magnetized Plasma

    SciTech Connect

    Moskaliuk, S. S.

    2010-01-01

    The polarization plane of the cosmic microwave background radiation (CMBR) can be rotated either in a space-time with metric of anisotropic type and in a magnetized plasma or in the presence of a quintessential background with pseudoscalar coupling to electromagnetism. A unified treatment of these three phenomena is presented for cold anisotropic plasma at the pre-recombination epoch. It is argued that the generalized expressions derived in the present study may be relevant for direct searches of a possible rotation of the cosmic microwave background polarization.

  13. B -mode polarization of the CMB and the cosmic neutrino background

    NASA Astrophysics Data System (ADS)

    Mohammadi, Rohoollah; Khodagholizadeh, Jafar; Sadegh, M.; Xue, She-Sheng

    2016-06-01

    It is known that in contrast with the E -mode polarization the B -mode polarization of the cosmic microwave background cannot be generated by the Compton scattering in the case of the scalar mode of metric perturbation. However, it is possible to generate the B mode by the Compton scattering in the case of the tensor mode of metric perturbation. For this reason, the ratio of tensor to scalar modes of metric perturbation (r ˜CB l/CE l ) is estimated by comparing the B -mode power spectrum with the E mode at least for small l . We study the cosmic microwave background polarization, especially the B mode due to the weak interaction of the cosmic neutrino background and cosmic microwave background, in addition to the Compton scattering in both cases of scalar and tensor metric perturbations. It is shown that the power spectrum CB l of the B -mode polarization receives some contributions from scalar and tensor modes, which have effects on the value of the r parameter. We also show that the B -mode polarization power spectrum can be used as an indirect probe into the cosmic neutrino background.

  14. A 145-GHz interferometer for measuring the anisotropy of the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Doriese, William Bertrand

    This thesis presents the design, construction, testing, and preliminary data analysis of MINT, the Millimeter INTerferometer. MINT is a 145-GHz, four-element interferometer designed to measure the anisotropy of the Cosmic Microwave Background (CMB) at spherical harmonics of ℓ = 800 to 1900. In this region of ℓ-space, the CMB angular power spectrum should exhibit an exponential damping due to a pair of effects related to the finite thickness of the last-scattering surface: photon diffusion and line-of-sight projection. Measurements in this region have already been made at 31 GHz by the Cosmic Background Imager (CBI). MINT's goal is to complement CBI by extending these results to a higher frequency that is much less prone to extra-galactic point-source contamination. MINT's mission is also complementary to that of the Microwave Anisotropy Probe (MAP) satellite. MINT observed the CMB in November and December, 2001, from an altitude of 17,000 feet in the Atacama Desert of northern Chile. We describe the performance of the instrument during the observing campaign. Based on radiometric hot/cold-load tests, the SIS-mixer-based receivers are found to have an average receiver noise temperature (double sideband) of 39 K in a 2-GHz IF bandwidth. The typical atmosphere contribution is 5 K. We assess the phase stability, gain stability, pointing accuracy, and overall sensitivity of the interferometer via observations of Mars and Jupiter, and find that the instrument is sufficiently stable to allow an ultimate experimental sensitivity at the few-μK level needed for detection of the CMB anisotropy.

  15. Optimization of background subtraction for image enhancement

    NASA Astrophysics Data System (ADS)

    Venetsky, Larry; Boczar, Ross; Lee-Own, Robert

    2013-05-01

    Analysis of foreground objects in scenery via image processing often involves a background subtraction process. This process aims to improve blob (connected component) content in the image. Quality blob content is often needed for defining regions of interest for object recognition and tracking. Three techniques are examined which optimize the background to be subtracted - genetic algorithm, an analytic solution based on convex optimization, and a related application of the CVX solver toolbox. These techniques are applied to a set of images and the results are compared. Additionally, a possible implementation architecture that uses multiple optimization techniques with subsequent arbitration to produce the best background subtraction is considered.

  16. The millimeter-wave bolometric interferometer (MBI) for observing the cosmic microwave background polarization

    NASA Astrophysics Data System (ADS)

    Kim, Jaiseung

    This thesis describes the Millimeter-wave Bolometric Interferometer (MBI) to measure the Cosmic Microwave Background Polarization (CMBP) anisotropy at angular scales 0.5°--1° and a center frequency of 90 GHz. The measurement of the CMBP anisotropy on these angular scales will put more stringent constraints on cosmological models and parameters. The prototype instrument employs four corrugated feedhorns and cooled bolometers. Using a Butler beam combiner, beams from four feedhorns are correlated, yielding interferometric measurements of the CMBP. From these interferometric measurements, we can reconstruct the image of polarization by aperture synthesis and estimate the power spectrum of the CMBP by maximum likelihood method. We describe aperture synthesis and maximum likelihood method. We present the result of the image reconstruction and the power spectrum estimation from simulated MBI observations. With the planned sensitivity of the MBI, the MBI will be able to estimate the E mode power spectra of the CMBP in the multipole range (150 <= l <= 300) and put upper bounds on the B mode power spectra in the relevant multipoles. In the end, we describe all-sky imaging method from interferometric measurements developed for the Einstein Probe Interferometer for Cosmology (EPIC), which is the satellite version of the MBI.

  17. Excess astrophysical photons from a 0.1-1 keV cosmic axion background.

    PubMed

    Conlon, Joseph P; Marsh, M C David

    2013-10-11

    Primordial decays of string theory moduli at z~10(12) naturally generate a dark radiation cosmic axion background with 0.1-1 keV energies. This cosmic axion background can be detected through axion-photon conversion in astrophysical magnetic fields to give quasithermal excesses in the extreme ultraviolet and soft x-ray bands. Substantial and observable luminosities may be generated even for axion-photon couplings <10(-11) GeV(-1). We propose that axion-photon conversion may explain the observed excess emission of soft x rays from galaxy clusters, and may also contribute to the diffuse unresolved cosmic x-ray background. We list a number of correlated predictions of the scenario. PMID:24160588

  18. Optical alignments of the Cosmic Background Explorer (COBE) observatory

    NASA Technical Reports Server (NTRS)

    Sampler, Henry P.

    1990-01-01

    The angular alignments and stabilities of multiple components in a single coordinate system were determined using various alignment tooling techniques. These techniques use autocollimation measurements with a first order theodolite and transformation of coordinates to determine the relative alignment between various components with respect to a common set of COBE spacecraft coordinate axes. Optical-mechanical alignment techniques were also used to integrate the flight COBE observatory attitude control system module that consists of gyros, reaction wheels, and a momentum wheel. Particular attention is given to the techniques for alignments and stabilities of the earth scanners, sun sensors, far IR absolute spectrophotometer, Diffuse Infrared Background Experiment, and differential microwave radiometer antenna horn boresights.

  19. Maser radiometer for cosmic background radiation anisotropy measurements

    NASA Astrophysics Data System (ADS)

    Fixsen, D. J.; Wilkinson, D. T.

    1982-06-01

    A maser amplifier was incorporated into a low noise radiometer designed to measure large-scale anisotropy in the 3 deg K microwave background radiation. To minimize emission by atmospheric water vapor and oxygen, the radiometer is flown in a small balloon to an altitude to 25 km. Three successful flights were made - two from Palestine, Texas and one from Sao Jose dos Campos, Brazil. Good sky coverage is important to the experiment. Data from the northern hemisphere flights has been edited and calibrated.

  20. Maser radiometer for cosmic background radiation anisotropy measurements

    NASA Technical Reports Server (NTRS)

    Fixsen, D. J.; Wilkinson, D. T.

    1982-01-01

    A maser amplifier was incorporated into a low noise radiometer designed to measure large-scale anisotropy in the 3 deg K microwave background radiation. To minimize emission by atmospheric water vapor and oxygen, the radiometer is flown in a small balloon to an altitude to 25 km. Three successful flights were made - two from Palestine, Texas and one from Sao Jose dos Campos, Brazil. Good sky coverage is important to the experiment. Data from the northern hemisphere flights has been edited and calibrated.

  1. Cosmic strings as the source of small-scale microwave background anisotropy

    NASA Astrophysics Data System (ADS)

    Pogosian, Levon; Tye, S.-H. Henry; Wasserman, Ira; Wyman, Mark

    2009-02-01

    Cosmic string networks generate cosmological perturbations actively throughout the history of the universe. Thus, the string sourced anisotropy of the cosmic microwave background is not affected by Silk damping as much as the anisotropy seeded by inflation. The spectrum of perturbations generated by strings does not match the observed CMB spectrum on large angular scales (ell < 1000) and is bounded to contribute no more than 10% of the total power on those scales. However, when this bound is marginally saturated, the anisotropy created by cosmic strings on small angular scales ell gtrsim 2000 will dominate over that created by the primary inflationary perturbations. This range of angular scales in the CMB is presently being measured by a number of experiments; their results will test this prediction of cosmic string networks soon.

  2. Cosmic strings as the source of small-scale microwave background anisotropy

    SciTech Connect

    Pogosian, Levon; Tye, S.-H. Henry; Wasserman, Ira; Wyman, Mark E-mail: tye@lepp.cornell.edu E-mail: mwyman@perimeterinstitute.ca

    2009-02-15

    Cosmic string networks generate cosmological perturbations actively throughout the history of the universe. Thus, the string sourced anisotropy of the cosmic microwave background is not affected by Silk damping as much as the anisotropy seeded by inflation. The spectrum of perturbations generated by strings does not match the observed CMB spectrum on large angular scales (l < 1000) and is bounded to contribute no more than 10% of the total power on those scales. However, when this bound is marginally saturated, the anisotropy created by cosmic strings on small angular scales l {approx}> 2000 will dominate over that created by the primary inflationary perturbations. This range of angular scales in the CMB is presently being measured by a number of experiments; their results will test this prediction of cosmic string networks soon.

  3. A Degree-Scale Measurement of the Anisotropy in the Cosmic Microwave Background

    NASA Technical Reports Server (NTRS)

    Wollack, Ed; Jarosik, Norm; Netterfield, Barth; Page, Lyman; Wilkinson, David

    1995-01-01

    We report the detection of anisotropy in the microwave sky at 3O GHz and at l deg angular scales. The most economical interpretation of the data is that the fluctuations are intrinsic to the cosmic microwave background. However, galactic free-free emission is ruled out with only 90% confidence. The most likely root-mean-squared amplitude of the fluctuations, assuming they are described by a Gaussian auto-correlation function with a coherence angle of 1.2 deg, is 41(+16/-13) (mu)K. We also present limits on the anisotropy of the polarization of the cosmic microwave background.

  4. Low-Frequency Measurments of the Cosmic Background RadiationSpectrum

    SciTech Connect

    Smoot, G.F.; De Amici, G.; Friedman, S.D.; Witebsky, C.; Sironi,G.; Bonelli, G.; Mandolesi, N.; Cortiglioni, S.; Morigi, G.; Partridge,R.B.; Danese, L.; De Zotti, G.

    1984-11-01

    The long-wavelength spectrum of the cosmic background radiation has been measured at five wavelengths (0.33, 0.9, 3.0, 6.3, and 12.0 cm). These measurements represent a continuation of the work reported by Smoot et al. (1983). The combine results have a weighted average of 2.73 {+-} 0.05 K and are consistent with past measurements. They limit the possible Compton distortion of the Cosmic Background Radiation spectrum to less than 8%.

  5. Determination of the Cosmic Radio Background from the Radio-Infrared Relation in Galaxies

    NASA Technical Reports Server (NTRS)

    Dwek, Eli; Barker, Michael K.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We use the radioactive flux correlation for star forming galaxies in the local universe to derive their contribution to the cosmic radio background (CRB). The CRB from these galaxies is therefore determined by the evolution of the comoving infrared luminosity density with redshift, which is constrained by galaxy number counts at various infrared wavelengths and by the cosmic infrared background. The research of ED was supported by NASA NRA 99-OSS-01 Astrophysics Theory Program. MB acknowledges the support of the "Research Opportunities for Undergraduates in the Laboratory for Astronomy and Solar Physics" for the summer student internship program at NASA/GSFC.

  6. Angular Anisotropies in the Cosmic Gamma-Ray Background as a Probe of Its Origin

    NASA Astrophysics Data System (ADS)

    Miniati, Francesco; Koushiappas, Savvas M.; Di Matteo, Tiziana

    2007-09-01

    Notwithstanding the advent of the Gamma-ray Large Area Space Telescope, theoretical models predict that a significant fraction of the cosmic γ-ray background (CGB), at a level of 20% of the currently measured value, will remain unresolved. The angular power spectrum of intensity fluctuations of the CGB contains information on its origin. We show that probing the latter on scales from a few tens of arcminutes to several degrees, together with complementary GLAST observations of γ-ray emission from galaxy clusters and the blazar luminosity function, can discriminate between a background that originates from unresolved blazars or cosmic rays accelerated at structure formation shocks.

  7. Cosmic 21 cm delensing of microwave background polarization and the minimum detectable energy scale of inflation.

    PubMed

    Sigurdson, Kris; Cooray, Asantha

    2005-11-18

    We propose a new method for removing gravitational lensing from maps of cosmic microwave background (CMB) polarization anisotropies. Using observations of anisotropies or structures in the cosmic 21 cm radiation, emitted or absorbed by neutral hydrogen atoms at redshifts 10 to 200, the CMB can be delensed. We find this method could allow CMB experiments to have increased sensitivity to a background of inflationary gravitational waves (IGWs) compared to methods relying on the CMB alone and may constrain models of inflation which were heretofore considered to have undetectable IGW amplitudes. PMID:16384131

  8. Early results from the Cosmic Background Explorer (COBE)

    NASA Technical Reports Server (NTRS)

    Mather, J. C.; Hauser, M. G.; Bennett, C. L.; Boggess, N. W.; Cheng, E. S.; Eplee, R. E., Jr.; Freudenreich, H. T.; Isaacman, R. B.; Kelsall, T.; Gulkis, S.

    1991-01-01

    Data obtained with the FIR Absolute Spectrophotometer, Differential Microwave Radiometers, and Diffuse IR Background Experiment (DIRBE) on the COBE satellite since its launch in November 1989 are briefly characterized. The COBE spacecraft and its 900-km 99-deg orbit are described; the scientific goals and capabilities of the instruments are reviewed; and sample DIRBE data are presented in a map and graph. Upper limits on the Comptonization parameter (y less than 0.001) and the chemical potential (mu less than 0.01 at the 3sigma level) are determined, and the spectrum of the dipole anisotropy is shown to be that of a Doppler-shifted blackbody. The DIRBE 100-micron sky brightness values at the ecliptic poles are found to be significantly lower than those measured by IRAS.

  9. Peaks in the Cosmic Microwave Background: Flat versus Open Models

    NASA Astrophysics Data System (ADS)

    Barreiro, R. B.; Sanz, J. L.; Martínez-González, E.; Cayón, L.; Silk, Joseph

    1997-03-01

    We present properties of the peaks (maxima) of the microwave background anisotropies expected in flat and open cold dark matter models. We obtain analytical expressions of several topological descriptors: mean number of maxima and the probability distribution of the Gaussian curvature and the eccentricity of the peaks. These quantities are calculated as functions of the radiation power spectrum, assuming a Gaussian distribution of temperature anisotropies. We present results for angular resolutions ranging from 5' to 20' (antenna FWHM), scales that are relevant for the MAP and COBRAS/SAMBA space missions and the ground-based interferometer experiments. Our analysis also includes the effects of noise. We find that the number of peaks can discriminate between standard cold dark matter models and that the Gaussian curvature distribution provides a useful test for these various models, whereas the eccentricity distribution cannot distinguish between them.

  10. AMiBA: Broadband Heterodyne Cosmic Microwave Background Interferometry

    NASA Astrophysics Data System (ADS)

    Chen, Ming-Tang; Li, Chao-Te; Hwang, Yuh-Jing; Jiang, Homin; Altamirano, Pablo; Chang, Chia-Hao; Chang, Shu-Hao; Chang, Su-Wei; Chiueh, Tzi-Dar; Chu, Tah-Hsiung; Han, Chih-Chiang; Huang, Yau-De; Kesteven, Michael; Kubo, Derek; Martin-Cocher, Pierre; Oshiro, Peter; Raffin, Philippe; Wei, Tashun; Wang, Huei; Wilson, Warwick; Ho, Paul T. P.; Huang, Chih-Wei; Koch, Patrick; Liao, Yu-Wei; Lin, Kai-Yang; Liu, Guo-Chin; Molnar, Sandor M.; Nishioka, Hiroaki; Umetsu, Keiichi; Wang, Fu-Cheng; Wu, Jiun-Huei Proty

    2009-04-01

    The Y. T. Lee Array for Microwave Background (AMiBA) has reported the first results on the detection of galaxy clusters via the Sunyaev-Zel'dovich effect. The objectives required small reflectors in order to sample large-scale structures (20'), while interferometry provided modest resolutions (2'). With these constraints, we designed for the best sensitivity by utilizing the maximum possible continuum bandwidth matched to the atmospheric window at 86-102 GHz, with dual polarizations. A novel wide-band analog correlator was designed that is easily expandable for more interferometer elements. Monolithic millimeter-wave integrated circuit technology was used throughout as much as possible in order to miniaturize the components and to enhance mass production. These designs will find application in other upcoming astronomy projects. AMiBA is now in operation since 2006, and we are in the process to expand the array from seven to 13 elements.

  11. Amplitude-Phase Analysis of Cosmic Microwave Background Maps

    NASA Astrophysics Data System (ADS)

    Novikov, D.; Naselsky, P.; Silk, J.

    We suggest the amplitude-phase analysis (APA) as a new method for the CMB image reconstruction. This method has been adopted for any kind of possible noise in the CMB observational data ( like point sources, dust emission, pixel and radiometer noise and so on). The important advantage of our scheme is that unlike other methods the phase analysis doesn't require any information about the expected CMB power spectra to subtract the noise. The only assumption we made is that the initial cosmological signal has a Gaussian nature. This method is very efficient computationally because it requires only O(Nln (N)) operations, where N is the number of pixels. Therefore, the full advantage of our scheme can be reached on very large data sets. Its efficiency has been successfully tested on simulated signals corresponding to MAP, PLANCK and RATAN-600 angular resolutions. P. Naselsky (TAC, Denmark), I. Novikov (TAC, Denmark)

  12. Cosmic Variance in the Nanohertz Gravitational Wave Background

    NASA Astrophysics Data System (ADS)

    Roebber, Elinore; Holder, Gilbert; Holz, Daniel E.; Warren, Michael

    2016-03-01

    We use large N-body simulations and empirical scaling relations between dark matter halos, galaxies, and supermassive black holes (SMBBHs) to estimate the formation rates of SMBBH binaries and the resulting low-frequency stochastic gravitational wave background (GWB). We find this GWB to be relatively insensitive (≲ 10%) to cosmological parameters, with only slight variation between wmap5 and Planck cosmologies. We find that uncertainty in the astrophysical scaling relations changes the amplitude of the GWB by a factor of ∼2. Current observational limits are already constraining this predicted range of models. We investigate the Poisson variance in the amplitude of the GWB for randomly generated populations of SMBBHs, finding a scatter of order unity per frequency bin below 10 nHz, and increasing to a factor of ∼10 near 100 nHz. This variance is a result of the rarity of the most massive binaries, which dominate the signal, and acts as a fundamental uncertainty on the amplitude of the underlying power law spectrum. This Poisson uncertainty dominates at ≳ 20 nHz, while at lower frequencies the dominant uncertainty is related to our poor understanding of the astrophysical scaling relations, although very low frequencies may be dominated by uncertainties related to the final parsec problem and the processes which drive binaries to the gravitational wave dominated regime. Cosmological effects are negligible at all frequencies.

  13. Bolometric Interferometry for Cosmic Microwave Background Polariztion Measurements

    NASA Astrophysics Data System (ADS)

    Malu, Siddharth

    2009-05-01

    CMB studies are now a data-rich field in astrophysics. The power spectrum of CMB is well measured and cosmological models have been characterized and polarization has been detected in the CMB. All results fit well within and are explained well by the inflationary paradigm. But current evidence for inflation is indirect. The next generation of CMB experiments will aim at providing the most direct evidence for inflation through the detection of B-modes in CMB polarization. Despite improvements in experimental techniques, it is as yet unclear what configuration and approach a CMB polarization experiment should adopt, in view of lack of information about polarization foregrounds and instrument systematic effects. We describe a novel approach to these measurements, called bolometric interferometry, which avoids many of the systematic errors found in imaging systems. In particular, we describe a prototype, the Millimeter-wave Bolometric Interferometer (MBI). We present a few promising approaches from our collaboration (BRAIN/MBI) and discuss plans for feasibility studies for detecting CMB polarization foregrounds and signals with adding interferometers.

  14. The space microwave interferometer and the search for cosmic background gravitational wave radiation

    NASA Technical Reports Server (NTRS)

    Anderson, Allen Joel

    1989-01-01

    Present and planned investigations which use interplanetary spacecraft for gravitational wave searches are severely limited in their detection capability. This limitation has to do both with the Earth-based tracking procedures used and with the configuration of the experiments themselves. It is suggested that a much improved experiment can now be made using a multiarm interferometer designed with current operating elements. An important source of gravitational wave radiation, the cosmic background, may well be within reach of detection with these procedures. It is proposed to make a number of experimental steps that can now be carried out using TDRSS spacecraft and would conclude in the establishment of an operating multiarm microwave interferometer. This interferometer is projected to have a sensitivity to cosmic background gravitational wave radiation with an energy of less than 10(exp -4) cosmic closure density and to periodic waves generating spatial strain approaching 10(exp -19) in the range 0.1 to 0.001 Hz.

  15. Cosmic microwave background dipole spectrum measured by the COBE FIRAS instrument

    NASA Technical Reports Server (NTRS)

    Fixsen, D. J.; Cheng, E. S.; Cottingham, D. A.; Eplee, R. E., Jr.; Isaacman, R. B.; Mather, J. C.; Meyer, S. S.; Noerdlinger, P. D.; Shafer, R. A.; Weiss, R.

    1994-01-01

    The Far-Infrared Absolute Spectrophotometer (FIRAS) instrument on the Cosmic Background Explorer (COBE) has determined the dipole spectrum of the cosmic microwave background radiation (CMBR) from 2 to 20/cm. For each frequency the signal is decomposed by fitting to a monopole, a dipole, and a Galactic template for approximately 60% of the sky. The overall dipole spectrum fits the derivative of a Planck function with an amplitude of 3.343 +/- 0.016 mK (95% confidence level), a temperature of 2.714 +/- 0.022 K (95% confidence level), and an rms deviation of 6 x 10(exp -9) ergs/sq cm/s/sr cm limited by a detector and cosmic-ray noise. The monopole temperature is consistent with that determined by direct measurement in the accompanying article by Mather et al.

  16. Noninvasive Reactor Imaging Using Cosmic-Ray Muons

    NASA Astrophysics Data System (ADS)

    Miyadera, H.; Fujita, K.; Karino, Y.; Kume, N.; Nakayama, K.; Sano, Y.; Sugita, T.; Yoshioka, K.; Morris, C. L.; Bacon, J. D.; Borozdin, K. N.; Perry, J. O.; Mizokami, S.; Otsuka, Y.; Yamada, D.

    2015-10-01

    Cosmic-ray-muon imaging is proposed to assess the damages to the Fukushima Daiichi reactors. Simulation studies showed capability of muon imaging to reveal the core conditions.The muon-imaging technique was demonstrated at Toshiba Nuclear Critical Assembly, where the uranium-dioxide fuel assembly was imaged with 3-cm spatial resolution after 1 month of measurement.

  17. Spectrum of the cosmic background radiation: early and recent measurements from the White Mountain Research Station

    SciTech Connect

    Smoot, G.F.

    1985-09-01

    The White Mountain Research Station has provided a support facility at a high, dry, radio-quiet site for measurements that have established the blackbody character of the cosmic microwave background radiation. This finding has confirmed the interpretation of the radiation as a relic of the primeval fireball and helped to establish the hot Big Bang theory as the standard cosmological model.

  18. First results of the COBE satellite measurement of the anisotropy of the cosmic microwave background radiation

    NASA Technical Reports Server (NTRS)

    Smoot, G. F.; Aymon, J.; De Amici, G.; Bennett, C. L.; Kogut, A.; Gulkis, S.; Backus, C.; Galuk, K.; Jackson, P. D.; Keegstra, P.

    1991-01-01

    The concept and operation of the Differential Microwave Radiometers (DMR) instrument aboard NASA's Cosmic Background Explorer satellite are reviewed, with emphasis on the software identification and subtraction of potential systematic effects. Preliminary results obtained from the first six months of DMR data are presented, and implications for cosmology are discussed.

  19. Cosmic Bubble Image Wins NRAO Contest

    NASA Astrophysics Data System (ADS)

    2006-10-01

    A striking image of an enormous bubble blown into the dusty gas disk of our own Milky Way galaxy has won first place in the National Radio Astronomy Observatory's second annual Radio Astronomy Image Contest. Dr. Jayanne English of the University of Manitoba led the team that made the winning image using data from the National Science Foundation's Very Large Array (VLA) in New Mexico and Robert C. Byrd Green Bank Telescope (GBT) in West Virginia. Cosmic Bubble Image Giant "Bubble" in Milky Way's Gas CREDIT: English et al., NRAO/AUI/NSF Click on image for large files and full information English and her collaborators Jeroen Stil and Russ Taylor, from the University of Calgary, will share the grand prize of $1,000 from Associated Universities, Inc., the research corporation that operates the observatory for the NSF. "We congratulate Dr. English for producing an outstanding image that beautifully illustrates the power of our radio telescopes," said NRAO Director Fred K.Y. Lo. The image contest is part of a broader NRAO effort to make radio astronomical data and images easily accessible and widely available to scientists, students, teachers, the general public, news media and science-education professionals. That effort includes an expanding image gallery on the observatory's Web site. English's winning image shows a giant bubble in the Milky Way's dusty gas disk. The bubble has been sculpted by the wind and radiation force from a few dozen hot, massive stars along with the explosive force of supernova explosions from dying stars. The bubble, seen in the faint radio glow of hydrogen gas, is some 30,000 light-years from Earth and measures 1,100 by 520 light-years. If the bubble, in the constellation Vulpecula, were visible to human eyes, it would appear to be eight times the diameter of the full Moon in the sky. The image was made using data collected as part of the VLA Galactic Plane Survey (VGPS), a set of systematic observations of the Milky Way. This survey, led by

  20. Estimating radiological background using imaging spectroscopy

    SciTech Connect

    Bernacki, Bruce E.; Schweppe, John E.; Stave, Sean C.; Jordan, David V.; Kulisek, Jonathan A.; Stewart, Trevor N.; Seifert, Carolyn E.

    2014-06-13

    Optical imaging spectroscopy is investigated as a method to estimate radiological background by spectral identification of soils, sediments, rocks, minerals and building materials derived from natural materials and assigning tabulated radiological emission values to these materials. Radiological airborne surveys are undertaken by local, state and federal agencies to identify the presence of radiological materials out of regulatory compliance. Detection performance in such surveys is determined by (among other factors) the uncertainty in the radiation background; increased knowledge of the expected radiation background will improve the ability to detect low-activity radiological materials. Radiological background due to naturally occurring radiological materials (NORM) can be estimated by reference to previous survey results, use of global 40K, 238U, and 232Th (KUT) values, reference to existing USGS radiation background maps, or by a moving average of the data as it is acquired. Each of these methods has its drawbacks: previous survey results may not include recent changes, the global average provides only a zero-order estimate, the USGS background radiation map resolutions are coarse and are accurate only to 1 km – 25 km sampling intervals depending on locale, and a moving average may essentially low pass filter the data to obscure small changes in radiation counts. Imaging spectroscopy from airborne or spaceborne platforms can offer higher resolution identification of materials and background, as well as provide imaging context information. AVIRIS hyperspectral image data is analyzed using commercial exploitation software to determine the usefulness of imaging spectroscopy to identify qualitative radiological background emissions when compared to airborne radiological survey data.

  1. Estimating radiological background using imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Bernacki, Bruce; Schweppe, John E.; Stave, Sean; Jordan, David; Kulisek, Jonathan; Stewart, Trevor; Seifert, Carolyn

    2014-06-01

    Optical imaging spectroscopy is investigated as a method to estimate radiological background by spectral identification of soils, sediments, rocks, minerals and building materials derived from natural materials and assigning tabulated radiological emission values to these materials. Radiological airborne surveys are undertaken by local, state and federal agencies to identify the presence of radiological materials out of regulatory compliance. Detection performance in such surveys is determined by (among other factors) the uncertainty in the radiation background; increased knowledge of the expected radiation background will improve the ability to detect low-activity radiological materials. Radiological background due to naturally occurring radiological materials (NORM) can be estimated by reference to previous survey results, use of global 40K, 238U, and 232Th (KUT) values, reference to existing USGS radiation background maps, or by a moving average of the data as it is acquired. Each of these methods has its drawbacks: previous survey results may not include recent changes, the global average provides only a zero-order estimate, the USGS background radiation map resolutions are coarse and are accurate only to 1 km - 25 km sampling intervals depending on locale, and a moving average may essentially low pass filter the data to obscure small changes in radiation counts. Imaging spectroscopy from airborne or spaceborne platforms can offer higher resolution identification of materials and background, as well as provide imaging context information. AVIRlS hyperspectral image data is analyzed using commercial exploitation software to determine the usefulness of imaging spectroscopy to identify qualitative radiological background emissions when compared to airborne radiological survey data.

  2. Estimation of Cosmic Induced Contamination in Ultra-low Background Detector Materials

    SciTech Connect

    Aguayo Navarrete, Estanislao; Kouzes, Richard T.; Orrell, John L.; Berguson, Timothy J.; Greene, Austen T.

    2012-08-01

    Executive Summary This document presents the result of investigating a way to reliably determine cosmic induced backgrounds for ultra-low background materials. In particular, it focuses on those radioisotopes produced by the interactions with cosmic ray particles in the detector materials that act as a background for experiments looking for neutrinoless double beta decay. This investigation is motivated by the desire to determine background contributions from cosmic ray activation of the electroformed copper that is being used in the construction of the MAJORANA DEMONSTRATOR. The most important radioisotope produced in copper that contributes to the background budget is 60Co, which has the potential to deposit energy in the region of interest of this experiment. Cobalt-60 is produced via cosmic ray neutron collisions in the copper. This investigation aims to provide a method for determining whether or not the copper has been exposed to cosmic radiation beyond the threshold which the Majorana Project has established as the maximum exposure. This threshold is set by the Project as the expected contribution of this source of background to the overall background budget. One way to estimate cosmic ray neutron exposure of materials on the surface of the Earth is to relate it to the cosmic ray muon exposure. Muons are minimum-ionizing particles and the available technologies to detect muons are easier to implement than those to detect neutrons. We present the results of using a portable, ruggedized muon detector, the µ-Witness made by our research group, for determination of muon exposure of materials for the MAJORANA DEMONSTRATOR. From the muon flux measurement, this report presents a method to estimate equivalent sea-level exposure, and then infer the neutron exposure of the tracked material and thus the cosmogenic activation of the copper. This report combines measurements of the muon flux taken by the µ-Witness detector with Geant4 simulations in order to assure our

  3. Cosmic microwave background snapshots: pre-WMAP and post-WMAP.

    PubMed

    Bond, J Richard; Contaldi, Carlo; Pogosyan, Dmitry

    2003-11-15

    We highlight the remarkable evolution in the cosmic microwave background (CMB) power spectrum C(l) as a function of multipole l over the past few years, and in the cosmological parameters for minimal inflation models derived from it: from anisotropy results before 2000; in 2000 and 2001 from Boomerang, Maxima and the Degree Angular Scale Interferometer (DASI), extending l to approximately 1000; and in 2002 from the Cosmic Background Imager (CBI), Very Small Array (VSA), ARCHEOPS and Arcminute Cosmology Bolometer Array Receiver (ACBAR), extending l to approximately 3000, with more from Boomerang and DASI as well. Pre-WMAP (pre-Wilkinson Microwave Anisotropy Probe) optimal band powers are in good agreement with each other and with the exquisite one-year WMAP results, unveiled in February 2003, which now dominate the l less, similar 600 bands. These CMB experiments significantly increased the case for accelerated expansion in the early Universe (the inflationary paradigm) and at the current epoch (dark energy dominance) when they were combined with "prior" probabilities on the parameters. The minimal inflation parameter set, [omega(b), omega(cdm), Omega(tot), Omega(Lambda), n(s), tau(C), sigma(8)], is applied in the same way to the evolving data. C(l) database and Monte Carlo Markov Chain (MCMC) methods are shown to give similar values, which are highly stable over time and for different prior choices, with the increasing precision best characterized by decreasing errors on uncorrelated "parameter eigenmodes". Priors applied range from weak ones to stronger constraints from the expansion rate (HST-h), from cosmic acceleration from supernovae (SN1) and from galaxy clustering, gravitational lensing and local cluster abundance (LSS). After marginalizing over the other cosmic and experimental variables for the weak + LSS prior, the pre-WMAP data of January 2003 compared with the post-WMAP data of March 2003 give Omega(tot) = 1.03(-0.04)(+0.05) compared with 1

  4. The diffuse far-ultraviolet cosmic background radiation field observed from the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Murthy, J.; Henry, R. C.; Feldman, P. D.; Tennyson, P. D.

    1989-01-01

    The paper presents 17-A resolution spectra of the diffuse far-ultraviolet (1200-1700 A) cosmic background in eight regions of the sky obtained from the Johns Hopkins University UVX experiment aboard the Space Shuttle Columbia (STS-61C) in January 1986. A spectrally flat background is found with brightnesses between 100 and 700 + or - 200 photons/sq cm s sr A, with some evidence for spatial variations, but not for the high-intensity regions found by other experiments.

  5. Ultrahigh energy photons, electrons, and neutrinos, the microwave background, and the universal cosmic-ray hypothesis

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1972-01-01

    The production of ultrahigh energy photons, electrons and neutrinos as the decay products of pions produced in photomeson interactions between cosmic ray nucleons and the blackbody microwave background is discussed in terms of the resultant energy spectra of these particles. Simple asymptotic formulas are given for calculating the ultrahigh energy photon spectrum predicted for the universal cosmic ray hypothesis and the resulting spectra are compared with those obtained previously by numerical means using a different propagation equation for the photons. Approximate analytic solutions for the photon spectra are given in terms of simple power-law energy functions and slowly varying logarithmic functions.

  6. 21-cm lensing and the cold spot in the cosmic microwave background.

    PubMed

    Kovetz, Ely D; Kamionkowski, Marc

    2013-04-26

    An extremely large void and a cosmic texture are two possible explanations for the cold spot seen in the cosmic microwave background. We investigate how well these two hypotheses can be tested with weak lensing of 21-cm fluctuations from the epoch of reionization measured with the Square Kilometer Array. While the void explanation for the cold spot can be tested with Square Kilometer Array, given enough observation time, the texture scenario requires significantly prolonged observations, at the highest frequencies that correspond to the epoch of reionization, over the field of view containing the cold spot. PMID:23679703

  7. Second dip as a signature of ultrahigh energy proton interactions with cosmic microwave background radiation.

    PubMed

    Berezinsky, V; Gazizov, A; Kachelrieb, M

    2006-12-01

    We discuss as a new signature for the interaction of extragalactic ultrahigh energy protons with cosmic microwave background radiation a spectral feature located at E= 6.3 x 10(19) eV in the form of a narrow and shallow dip. It is produced by the interference of e+e(-)-pair and pion production. We show that this dip and, in particular, its position are almost model-independent. Its observation by future ultrahigh energy cosmic ray detectors may give the conclusive confirmation that an observed steepening of the spectrum is caused by the Greisen-Zatsepin-Kuzmin effect. PMID:17280191

  8. Background estimation in nonlinear image restoration.

    PubMed

    van Kempen, G M; van Vliet, L J

    2000-03-01

    One of the essential ways in which nonlinear image restoration algorithms differ from linear, convolution-type image restoration filters is their capability to restrict the restoration result to nonnegative intensities. The iterative constrained Tikhonov-Miller (ICTM) algorithm, for example, incorporates the nonnegativity constraint by clipping all negative values to zero after each iteration. This constraint will be effective only when the restored intensities have near-zero values. Therefore the background estimation will have an influence on the effectiveness of the nonnegativity constraint of these algorithms. We investigated quantitatively the dependency of the performance of the ICTM, Carrington, and Richardson-Lucy algorithms on the estimation of the background and compared it with the performance of the linear Tikhonov-Miller restoration filter. We found that the performance depends critically on the background estimation: An underestimation of the background will make the nonnegativity constraint ineffective, which results in a performance that does not differ much from the Tikhonov-Miller filter performance. A (small) overestimation, however, degrades the performance dramatically, since it results in a clipping of object intensities. We propose a novel general method to estimate the background based on the dependency of nonlinear restoration algorithms on the background, and we demonstrate its applicability on real confocal images. PMID:10708022

  9. Exact scale-invariant background of gravitational waves from cosmic defects.

    PubMed

    Figueroa, Daniel G; Hindmarsh, Mark; Urrestilla, Jon

    2013-03-01

    We demonstrate that any scaling source in the radiation era produces a background of gravitational waves with an exact scale-invariant power spectrum. Cosmic defects, created after a phase transition in the early universe, are such a scaling source. We emphasize that the result is independent of the topology of the cosmic defects, the order of phase transition, and the nature of the symmetry broken, global or gauged. As an example, using large-scale numerical simulations, we calculate the scale-invariant gravitational wave power spectrum generated by the dynamics of a global O(N) scalar theory. The result approaches the large N theoretical prediction as N(-2), albeit with a large coefficient. The signal from global cosmic strings is O(100) times larger than the large N prediction. PMID:23521248

  10. Born-corrections to weak lensing of the cosmic microwave background temperature and polarization anisotropies

    NASA Astrophysics Data System (ADS)

    Hagstotz, Steffen; Schäfer, Björn Malte; Merkel, Philipp M.

    2015-11-01

    Many weak-lensing calculations make use of the Born approximation where the light ray is approximated by a straight path. We examine the effect of Born-corrections for lensing of the cosmic microwave background (CMB) in an analytical approach by taking perturbative corrections to the geodesic into account. The resulting extra power in the lensing potential spectrum is comparable to the power generated by non-linear structure formation and affects especially the polarization spectra, leading to relative changes of the order of 10-3 for the E-mode spectrum and several per cent on all scales to the B-mode spectrum. In contrast, there is only little change of spectra involving the CMB temperature. Additionally, the corrections excite one more degree of freedom resulting in a deflection component which cannot be described as a gradient of the lensing potential as it is related to image rotation in lens-lens coupling. We estimate the magnitude of this effect on the CMB spectra and find it to be negligible.

  11. Limits on Arcminute Scale Cosmic Microwave Background Anisotropy with the BIMA Array

    NASA Technical Reports Server (NTRS)

    Holzapfel, W. L.; Carlstrom, J. E.; Grego, L.; Holder, G. P.; Joy, M. K.; Reese, E. D.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We have used the Berkeley-Illinois-Maryland-Association (BIMA) millimeter array outfitted with sensitive cm-wave receivers to search for Cosmic Microwave Background (CMB) anisotropies on arcminute scales. The interferometer was placed in a compact configuration which produces high brightness sensitivity, while providing discrimination against point sources. Operating at a frequency of 28.5 GHz, the FWHM primary beam of the instrument is 6.6 arcminutes. We have made sensitive images of seven fields, five of which where chosen specifically to have low IR dust contrast and be free of bright radio sources. Additional observations with the Owens Valley Radio Observatory (OVRO) millimeter array were used to assist in the location and removal of radio point sources. Applying a Bayesian analysis to the raw visibility data, we place limits on CMB anisotropy flat-band power Q_flat = 5.6 (+3.0, -5.6) uK and Q_flat < 14.1 uK at 68% and 95% confidence. The sensitivity of this experiment to flat band power peaks at a multipole of l = 5470, which corresponds to an angular scale of approximately 2 arcminutes The most likely value of Q_flat is similar to the level of the expected secondary anisotropies.

  12. Limits on Arcminute-Scale Cosmic Microwave Background Anisotropy at 28.5 GHz

    NASA Technical Reports Server (NTRS)

    Holzapfel, W. L.; Carlstrom, J. E.; Grego, L.; Holder, G.; Joy, M.; Reese, E. D.

    2000-01-01

    We have used the Berkeley-Illinois-Maryland Association (BIMA) millimeter array outfitted with sensitive centimeter-wave receivers to search for cosmic microwave background (CMB) anisotropies on arcminute scales. The interferometer was placed in a compact configuration that produces high brightness sensitivity, while providing discrimination against point sources. Operating at a frequency of 28.5 GHz, the FWHM primary beam of the instrument is approximately 6'.6. We have made sensitive images of seven fields, four of which where chosen specifically to have low infrared dust contrast and to be free of bright radio sources. Additional observations with the Owens Valley Radio Observatory (OVRO) millimeter array were used to assist in the location and removal of radio point sources. Applying a Bayesian analysis to the raw visibility data, we place limits on CMB anisotropy flat-band power of Q(sub flat) = 5.6(sub -5.6)(exp 3.0) microK and Q(sub flat) < 14.1 microK at 68% and 95% confidence, respectively. The sensitivity of this experiment to flat-band power peaks at a multipole of I = 5470, which corresponds to an angular scale of approximately 2'. The most likely value of Q(sub flat) is similar to the level of the expected secondary anisotropies.

  13. Neutral particle background in cosmic ray telescopes composed of silicon solid state detectors

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.; Stone, E. C.; Vogt, R. E.

    1977-01-01

    The energy loss-spectrum of secondary charged particles produced by the interaction of gamma-rays and energetic neutrons in silicon solid state detectors has been measured with a satellite-borne cosmic ray telescope. In the satellite measurements presented here two distinct neutral background effects are identified: secondary protons and alpha particles with energies of about 2 to 100 MeV produced by neutron interactions, and secondary electrons with energies of about 0.2 to 10 MeV produced by X-ray interactions. The implications of this neutral background for satellite measurements of low energy cosmic rays are discussed, and suggestions are given for applying these results to other detector systems in order to estimate background contamination and optimize detector system design.

  14. ACWI: an experiment to image the Cosmic Web from Antarctica

    NASA Astrophysics Data System (ADS)

    Moore, Anna M.; Martin, Christopher; Maitless, Noam C.; Travouillon, Tony

    2008-07-01

    The Antarctic Cosmic Web Imager (ACWI) is a dedicated 2m-class telescope specifically designed to discover and map resonance UV line emission from the Intergalactic Medium (IGM) and to explore the low surface brightness universe. IGM mapping will provide a new measurement of large-scale structure and the distribution of dark matter over a large and unique range in overdensity. The South Pole provides a location with (1) a target elevation that is constant during observation hence sees constant airmass (2) the lowest measured extinction of any ground based site (3) a low and constant ecliptic elevation and hence zodiacal emission away from the target location and (4) long duration nights yielding stable sky and instrument properties enabling the required accurate sky subtraction. These factors combined imply a sky background that is the most stable of any ground-based site, a requirement for this particular science case where the subtraction of sky background, rather than the image quality, must be exquisite. We present the baseline instrument design that is catered to perform this science case only and is not a general purpose instrument, increasing robustness and reliability.

  15. Electromagnetic Design of Feedhorn-Coupled Transition-Edge Sensors for Cosmic Microwave Background Polarimetery

    NASA Technical Reports Server (NTRS)

    Chuss, David T.

    2011-01-01

    Observations of the cosmic microwave background (CMB) provide a powerful tool for probing the evolution of the early universe. Specifically, precision measurement of the polarization of the CMB enables a direct test for cosmic inflation. A key technological element on the path to the measurement of this faint signal is the capability to produce large format arrays of background-limited detectors. We describe the electromagnetic design of feedhorn-coupled, TES-based sensors. Each linear orthogonal polarization from the feed horn is coupled to a superconducting microstrip line via a symmetric planar orthomode transducer (OMT). The symmetric OMT design allows for highly-symmetric beams with low cross-polarization over a wide bandwidth. In addition, this architecture enables a single microstrip filter to define the passband for each polarization. Care has been taken in the design to eliminate stray coupling paths to the absorbers. These detectors will be fielded in the Cosmology Large Angular Scale Surveyor (CLASS).

  16. Cosmic Infrared Background anisotropies as a window into primordial non-Gaussianity

    NASA Astrophysics Data System (ADS)

    Tucci, Marco; Desjacques, Vincent; Kunz, Martin

    2016-08-01

    The angular power spectrum of the cosmic infrared background (CIB) is a sensitive probe of the local primordial bispectrum. CIB measurements are integrated over a large volume so that the scale dependent bias from the primordial non-Gaussianity leaves a strong signal in the CIB power spectrum. Although galactic dust dominates over the non-Gaussian CIB signal, it is possible to mitigate the dust contamination with enough frequency channels, especially if high frequencies such as the Planck 857 GHz channel are available. We show that, in this case, measurements of the cosmic microwave background from future space missions should be able to probe the local bispectrum shape down to an amplitude |fNL| < 1.

  17. Quasi-stellar objects in the intergalactic medium: Source for the cosmic X-ray background

    SciTech Connect

    Sherman, R.D.

    1980-06-15

    QSOs are regarded as sources of both electromagnetic radiation and ejected matter that heat and ionize a dense intergalactic medium (IGM). Using current estimates of QSO luminosity, number density, evolution, and spectral index, we study three viable models: the diffuse cosmic X-ray background is (1) due entirely to thermal Bremsstrahlung of the IGM, (2) completely supplied by QSO X-radiation, (3) or a combination of both. The upper limits on an IGM fractional density with respect to closure are ..cap omega..=0.26, 0.24, and 0.21 for pure collisional, photo/collisional mixture, and pure photoionization, respectively. These calculations give emission spectra, Compton distortion of the cosmic microwave background, and optical depths to distant OSOs for comparison with relevant data.

  18. Measurement of the cosmic microwave background spectrum by the COBE FIRAS instrument

    NASA Technical Reports Server (NTRS)

    Mather, J. C.; Cheng, E. S.; Cottingham, D. A.; Eplee, R. E., Jr.; Fixsen, D. J.; Hewagama, T.; Isaacman, R. B.; Jensen, K. A.; Meyer, S. S.; Noerdlinger, P. D.

    1994-01-01

    The cosmic microwave background radiation (CMBR) has a blackbody spectrum within 3.4 x 10(exp -8) ergs/sq cm/s/sr cm over the frequency range from 2 to 20/cm (5-0.5 mm). These measurements, derived from the Far-Infrared Absolute Spectrophotomer (FIRAS) instrument on the Cosmic Background Explorer (COBE) satellite, imply stringent limits on energy release in the early universe after t approximately 1 year and redshift z approximately 3 x 10(exp 6). The deviations are less than 0.30% of the peak brightness, with an rms value of 0.01%, and the dimensionless cosmological distortion parameters are limited to the absolute value of y is less than 2.5 x 10(exp -5) and the absolute value of mu is less than 3.3 x 10(exp -4) (95% confidence level). The temperature of the CMBR is 2.726 +/- 0.010 K (95% confidence level systematic).

  19. Low Frequency Measurement of the Spectrum of the Cosmic Background Radiation

    DOE R&D Accomplishments Database

    Smoot, G. F.; De Amici, G.; Friedman, S. D.; Witebsky, C.; Mandolesi, N.; Partridge, R. B.; Sironi, G.; Danese, L.; De Zotti, G.

    1983-06-01

    We have made measurements of the cosmic background radiation spectrum at 5 wavelengths (0.33, 0.9, 3, 6.3, and 12 cm) using radiometers with wavelength-scaled corrugated horn antennas having very low sidelobes. A single large-mouth (0.7 m diameter) liquid-helium-cooled absolute reference load was used for all five radiometers. The results of the observations are consistent with previous measurements and represent a significant improvement in accuracy.

  20. Diffuse cosmic gamma-ray background as a probe of cosmological gravitino regeneration and decay

    SciTech Connect

    Olive, K.A.; Silk, J.

    1985-11-18

    We predict the presence of a spectral feature in the isotropic cosmic gamma-ray background associated with gravitino decays at high red shifts. With a gravitino abundance that falls in the relatively narrow range expected for thermally regenerated gravitinos following an inflationary epoc in the very early universe, gravitinos of mass several gigaelectronvolts are found to yield an appreciable flux of 1--10-MeV diffuse gamma rays.

  1. Harmonic inpainting of the cosmic microwave background sky: Formulation and error estimate

    SciTech Connect

    Inoue, Kaiki Taro; Cabella, Paolo; Komatsu, Eiichiro

    2008-06-15

    We develop a new interpolation scheme, based on harmonic inpainting, for reconstructing the cosmic microwave background temperature data within the Galaxy mask from the data outside the mask. We find that, for scale-invariant isotropic random Gaussian fluctuations, the developed algorithm reduces the errors in the reconstructed map for the odd-parity modes significantly for azimuthally symmetric masks with constant galactic latitudes. For a more realistic Galaxy mask, we find a modest improvement in the even-parity modes as well.

  2. Ultra-relativistic thermodynamics and aberrations of the cosmic microwave background radiation

    NASA Astrophysics Data System (ADS)

    Lee, Jeffrey S.; Cleaver, Gerald B.

    2015-03-01

    Ultra-relativistic inertial and non-inertial reference frames would be subjected to a forward-directed heat bath from the Lorentz transformed temperature of the Cosmic Microwave Background (CMB) radiation. Although the Lorentz transformations of heat and temperature continue to be unresolved issues in the literature,1-6 this paper makes use of occupation number (number density of occupied states per phase space element) to support a Lorentz factor inflation of the rest frame temperature. Additionally, Doppler Boosting is examined.

  3. First Detection of the Acoustic Oscillation Phase Shift Expected from the Cosmic Neutrino Background.

    PubMed

    Follin, Brent; Knox, Lloyd; Millea, Marius; Pan, Zhen

    2015-08-28

    The unimpeded relativistic propagation of cosmological neutrinos prior to recombination of the baryon-photon plasma alters gravitational potentials and therefore the details of the time-dependent gravitational driving of acoustic oscillations. We report here a first detection of the resulting shifts in the temporal phase of the oscillations, which we infer from their signature in the cosmic microwave background temperature power spectrum. PMID:26371637

  4. Non-Gaussianity in the cosmic microwave background anisotropies at recombination in the squeezed limit

    SciTech Connect

    Bartolo, N.; Matarrese, S.; Riotto, A. E-mail: sabino.matarrese@pd.infn.it

    2012-02-01

    We estimate analytically the second-order cosmic microwave background temperature anisotropies at the recombination epoch in the squeezed limit and we deduce the contamination of the primordial local non-Gaussianity. We find that the level of contamination corresponds to f{sub NL}{sup con} = O(1) which is below the sensitivity of present experiments and smaller than the value O(5) recently claimed in the literature.

  5. Small-scale primordial magnetic fields and anisotropies in the cosmic microwave background radiation

    SciTech Connect

    Jedamzik, Karsten; Abel, Tom E-mail: tabel@slac.stanford.edu

    2013-10-01

    It is shown that small-scale magnetic fields present before recombination induce baryonic density inhomogeneities of appreciable magnitude. The presence of such inhomogeneities changes the ionization history of the Universe, which in turn decreases the angular scale of the Doppler peaks and increases Silk damping by photon diffusion. This unique signature could be used to (dis)prove the existence of primordial magnetic fields of strength as small as B ≅ 10{sup −11} Gauss by cosmic microwave background observations.

  6. Review of Cosmic Background Radiation Spectrum Measurements:Limits on Distortions, Energy Release, and Cosmological Processes

    SciTech Connect

    Smoot, G.F.

    1986-01-01

    This paper reviews the three major cosmic microwave background radiation (CMBR) spectrum measurement programs conducted and published since the last (XVII) IAU General Assembly. The results are consistent with a Planckian spectrum with temperature 2.72 {+-} 0.03 K spanning a wavelength range of 0.1 to 12 cm. Limits on possible distortions and implications are outlined. Ongoing and future measurements are discussed.

  7. Review of cosmic background radiation spectrum measurements: limits on distortions, energy release, and cosmological processes

    SciTech Connect

    Smoot, G.F.

    1986-01-01

    This paper reviews the three major cosmic microwave background radiation (CMBR) spectrum measurement programs conducted and published since the last (XVII) IAU General Assembly. The results are consistent with a Planckian spectrum with temperature 2.72 +- 0.03 K spanning a wavelength range of 0.1 to 12 cm. Limits on possible distortions and implications are outlined. Ongoing and future measurements are discussed.

  8. On the radiative and thermodynamic properties of the cosmic radiations using COBE FIRAS instrument data: I. Cosmic microwave background radiation

    NASA Astrophysics Data System (ADS)

    Fisenko, Anatoliy I.; Lemberg, Vladimir

    2014-07-01

    Using the explicit form of the functions to describe the monopole and dipole spectra of the Cosmic Microwave Background (CMB) radiation, the exact expressions for the temperature dependences of the radiative and thermodynamic functions, such as the total radiation power per unit area, total energy density, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume, and pressure in the finite range of frequencies v 1≤ v≤ v 2 are obtained. Since the dependence of temperature upon the redshift z is known, the obtained expressions can be simply presented in z representation. Utilizing experimental data for the monopole and dipole spectra measured by the COBE FIRAS instrument in the 60-600 GHz frequency interval at the temperature T=2.72548 K, the values of the radiative and thermodynamic functions, as well as the radiation density constant a and the Stefan-Boltzmann constant σ are calculated. In the case of the dipole spectrum, the constants a and σ, and the radiative and thermodynamic properties of the CMB radiation are obtained using the mean amplitude T amp=3.358 mK. It is shown that the Doppler shift leads to a renormalization of the radiation density constant a, the Stefan-Boltzmann constant σ, and the corresponding constants for the thermodynamic functions. The expressions for new astrophysical parameters, such as the entropy density/Boltzmann constant, and number density of CMB photons are obtained. The radiative and thermodynamic properties of the Cosmic Microwave Background radiation for the monopole and dipole spectra at redshift z≈1089 are calculated.

  9. Evidence of lensing of the cosmic microwave background by dark matter halos.

    PubMed

    Madhavacheril, Mathew; Sehgal, Neelima; Allison, Rupert; Battaglia, Nick; Bond, J Richard; Calabrese, Erminia; Caligiuri, Jerod; Coughlin, Kevin; Crichton, Devin; Datta, Rahul; Devlin, Mark J; Dunkley, Joanna; Dünner, Rolando; Fogarty, Kevin; Grace, Emily; Hajian, Amir; Hasselfield, Matthew; Hill, J Colin; Hilton, Matt; Hincks, Adam D; Hlozek, Renée; Hughes, John P; Kosowsky, Arthur; Louis, Thibaut; Lungu, Marius; McMahon, Jeff; Moodley, Kavilan; Munson, Charles; Naess, Sigurd; Nati, Federico; Newburgh, Laura; Niemack, Michael D; Page, Lyman A; Partridge, Bruce; Schmitt, Benjamin; Sherwin, Blake D; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Thornton, Robert; Van Engelen, Alexander; Ward, Jonathan T; Wollack, Edward J

    2015-04-17

    We present evidence of the gravitational lensing of the cosmic microwave background by 10(13) solar mass dark matter halos. Lensing convergence maps from the Atacama Cosmology Telescope Polarimeter (ACTPol) are stacked at the positions of around 12 000 optically selected CMASS galaxies from the SDSS-III/BOSS survey. The mean lensing signal is consistent with simulated dark matter halo profiles and is favored over a null signal at 3.2σ significance. This result demonstrates the potential of microwave background lensing to probe the dark matter distribution in galaxy group and galaxy cluster halos. PMID:25933304

  10. Statistical evidence from fine-scale anisotropies in the cosmic background radiation

    NASA Astrophysics Data System (ADS)

    Zabotin, N. A.; Naselskij, P. D.

    1985-12-01

    The use of more sensitive radio telescopes to identify individual structural features in the distribution of Delta T/T over the celestial sphere, and thus obtain information on the fine-scale anisotropy of the cosmic background radiation, is discussed. By analyzing the statistical parameters of pips in the microwave background temperature fluctuations due to regions which had anomalously strong metric perturbations during the hydrogen recombination era, evidence on the correlation properties of that anisotropy can be gained even if the anisotropy is two to three times weaker than the prevailing noise levels of instrumental, atmospheric, galactic, and extragalactic origin.

  11. Cosmic far-ultraviolet background radiation - Probe of a dense hot intergalactic medium

    NASA Technical Reports Server (NTRS)

    Sherman, R. D.; Silk, J.

    1979-01-01

    Line and continuum radiation fluxes have been computed for a wide range of enriched intergalactic medium (IGM) models. Observations of the diffuse extragalactic light at optical and far-ultraviolet wavelengths are found to provide a potentially important probe of a dense hot intergalactic medium. If the diffuse X-ray background is produced by this gas, the models constrain the cosmological density parameter (Omega) to be less than 0.4. The associated Compton distortions of the cosmic blackbody background radiation and the optical depths to distant quasars at X-ray wavelengths are also evaluated.

  12. Statistical evidence from fine-scale anisotropies in the cosmic background radiation

    SciTech Connect

    Zabotin, N.A.; Naselskii, P.D.

    1985-12-01

    The use of more sensitive radio telescopes to identify individual structural features in the distribution of Delta T/T over the celestial sphere, and thus obtain information on the fine-scale anisotropy of the cosmic background radiation, is discussed. By analyzing the statistical parameters of pips in the microwave background temperature fluctuations due to regions which had anomalously strong metric perturbations during the hydrogen recombination era, evidence on the correlation properties of that anisotropy can be gained even if the anisotropy is two to three times weaker than the prevailing noise levels of instrumental, atmospheric, galactic, and extragalactic origin. 7 references.

  13. MADmap: A Massively Parallel Maximum-Likelihood Cosmic Microwave Background Map-Maker

    SciTech Connect

    Cantalupo, Christopher; Borrill, Julian; Jaffe, Andrew; Kisner, Theodore; Stompor, Radoslaw

    2009-06-09

    MADmap is a software application used to produce maximum-likelihood images of the sky from time-ordered data which include correlated noise, such as those gathered by Cosmic Microwave Background (CMB) experiments. It works efficiently on platforms ranging from small workstations to the most massively parallel supercomputers. Map-making is a critical step in the analysis of all CMB data sets, and the maximum-likelihood approach is the most accurate and widely applicable algorithm; however, it is a computationally challenging task. This challenge will only increase with the next generation of ground-based, balloon-borne and satellite CMB polarization experiments. The faintness of the B-mode signal that these experiments seek to measure requires them to gather enormous data sets. MADmap is already being run on up to O(1011) time samples, O(108) pixels and O(104) cores, with ongoing work to scale to the next generation of data sets and supercomputers. We describe MADmap's algorithm based around a preconditioned conjugate gradient solver, fast Fourier transforms and sparse matrix operations. We highlight MADmap's ability to address problems typically encountered in the analysis of realistic CMB data sets and describe its application to simulations of the Planck and EBEX experiments. The massively parallel and distributed implementation is detailed and scaling complexities are given for the resources required. MADmap is capable of analysing the largest data sets now being collected on computing resources currently available, and we argue that, given Moore's Law, MADmap will be capable of reducing the most massive projected data sets.

  14. Cosmic microwave background with Brans-Dicke gravity. II. Constraints with the WMAP and SDSS data

    NASA Astrophysics Data System (ADS)

    Wu, Feng-Quan; Chen, Xuelei

    2010-10-01

    Using the covariant formalism developed in a companion paper [F.-Q. Wu, L. E. Qiang, X. Wang, and X. Chen, preceding Article, Phys. Rev. DPRVDAQ1550-7998 82, 083002 (2010)] (paper I), we derive observational constraints on the Brans-Dicke model in a flat Friedmann-Lemaître-Robertson-Walker universe with a cosmological constant and cold dark matter. The CMB observations we use include the Wilkinson Microwave Anisotropy Probe 5 yr data, the Arcminute Cosmology Bolometer Array Receiver 2007 data, the Cosmic Background Imager polarization data, and the Balloon Observations of Millimetric Extragalactic Radiation and Geophysics 2003 flight data. For the large scale structure we use the matter power spectrum data measured with the luminous red galaxy survey of the Sloan Digital Sky Survey Data Release 4. We parametrize the Brans-Dicke parameter ω with a new parameter ζ=ln⁡(1/ω+1), and use the Markov-Chain Monte Carlo method to explore the parameter space. We find that using CMB data alone, one could place some constraints on positive ζ or ω, but negative ζ or ω could not be constrained effectively. However, with additional large scale structure data, one could break the degeneracy at ζ<0. The 2σ (95.5%) bound on ζ is -0.00837<ζ<0.01018 (corresponding to ω<-120.0 or ω>97.8). We also obtained constraints on G˙/G, the rate of change of G at present, as -1.75×10-12yr-1

  15. Measurements and simulations of the cosmic-ray-induced neutron background

    NASA Astrophysics Data System (ADS)

    Becchetti, M. F.; Flaska, M.; Clarke, S. D.; Pozzi, S. A.

    2015-03-01

    The cosmic-ray-induced neutron background at ground level has been measured and simulated in conjunction with EJ-309 organic liquid scintillators with an approximate deposited energy range of 0.5-6 MeV. Specifically, the pulse height distributions, net neutron count rates, and angular dependences were obtained. The simulations were carried out using the Monte Carlo transport code MCNPX-PoliMi combined with the (Cosmic-Ray Shower Generator) CRY source subroutine that returns secondary particles produced by cosmic rays. A scaling formula from literature was also implemented in the simulation. The angular dependence of the neutron count rate was measured by collimating the liquid scintillator with polyethylene to attain 18° angular resolution from 0° downwards to 72° horizontally. The neutron count rate was measured to be 23.10±1.69 h-1 sr-1 at 0°, and 7.20±0.78 h-1 sr-1 at 72°. The simulations and measurements compare well and show similar cosine anisotropy for the angular distribution. The study thus shows that the neutron background response in detector systems can be efficiently and accurately simulated using the procedures described.

  16. Tracing the first stars with fluctuations of the cosmic infrared background.

    PubMed

    Kashlinsky, A; Arendt, R G; Mather, J; Moseley, S H

    2005-11-01

    The deepest space- and ground-based observations find metal-enriched galaxies at cosmic times when the Universe was less than 1 Gyr old. These stellar populations had to be preceded by the metal-free first stars, known as 'population III'. Recent cosmic microwave background polarization measurements indicate that stars started forming early--when the Universe was < or =200 Myr old. It is now thought that population III stars were significantly more massive than the present metal-rich stellar populations. Although such sources will not be individually detectable by existing or planned telescopes, they would have produced significant cosmic infrared background radiation in the near-infrared, whose fluctuations reflect the conditions in the primordial density field. Here we report a measurement of diffuse flux fluctuations after removing foreground stars and galaxies. The anisotropies exceed the instrument noise and the more local foregrounds; they can be attributed to emission from population III stars, at an era dominated by these objects. PMID:16267547

  17. Is the Cosmic Microwave Background a Shell Around Us? or are the Microwaves Everywhere in the Universe?

    NASA Technical Reports Server (NTRS)

    Mather, John

    2015-01-01

    A: The cosmic microwave background (CMB) radiation fills the universe and travels in all directions. As we see it from here in satellite maps, it is about equally bright in all directions, and thats one of the main reasons we know its cosmic.

  18. Cosmic X-ray and gamma-ray background from dark matter annihilation

    NASA Astrophysics Data System (ADS)

    Zavala, Jesús; Vogelsberger, Mark; Slatyer, Tracy R.; Loeb, Abraham; Springel, Volker

    2011-06-01

    The extragalactic background light (EBL) observed at multiple wavelengths is a promising tool to probe the nature of dark matter. This radiation might contain a significant contribution from gamma-rays produced promptly by dark matter particle annihilation in the many halos and subhalos within our past-light cone. Additionally, the electrons and positrons produced in the annihilation give energy to the cosmic microwave photons to populate the EBL with X-rays and gamma-rays. To study these signals, we create full-sky maps of the expected radiation from both of these contributions using the high-resolution Millennium-II simulation of cosmic structure formation. Our method also accounts for a possible enhancement of the annihilation rate by a Sommerfeld mechanism due to a Yukawa interaction between the dark matter particles prior to annihilation. We use upper limits on the contributions of unknown sources to the EBL to constrain the intrinsic properties of dark matter using a model-independent approach that can be employed as a template to test different particle physics models. These upper limits are based on observational measurements spanning 8 orders of magnitude in energy (from soft X-rays measured by the CHANDRA satellite to gamma-rays measured by the Fermi satellite), and on expectations for the contributions from nonblazar active galactic nuclei, blazars and star-forming galaxies. To exemplify this approach, we analyze a set of benchmark Sommerfeld-enhanced models that give the correct abundance of dark matter, satisfy constraints from the cosmic microwave background, and fit the cosmic ray spectra measured by PAMELA and Fermi without any contribution from local substructure. We find that these models are in conflict with the EBL constraints unless the contribution of unresolved substructure is small and the dark matter annihilation signal dominates the EBL. We conclude that provided the collisionless cold dark matter paradigm is accurate, even for

  19. Cosmic Background Measurements at a Proposed Underground Laboratory by the REGARD Muontomograph

    NASA Astrophysics Data System (ADS)

    Oláh, L.; Surányi, G.; Barnaföldi, G. G.; Bemmerer, D.; Hamar, G.; Melegh, H. G.; Varga, D.

    2016-01-01

    A portable cosmic particle tracking detector has been developed by the REGARD group with angular resolution of 10 mrad. The Close Cathode Chamber-based tracking system is optimized for environmental and geophysical applications with its weight of 15 kg and size of 51 cm × 43 cm × 32 cm. Our aim was to determine the cosmic background at the site of the proposed accelerator and experimental facilities at an approximate 50 meter depth in Felsenkeller, Dresden, Germany. Here, we present our high-precision muon flux measurements, which have been performed during 44 days in one of the tunnels. Angular acceptance of our mapping covered full 2π solid angle of the upper hemisphere. The maximum flux value is found to be below 2.5 m-2sr-1s-1.

  20. The cosmic microwave background bispectrum from the non-linear evolution of the cosmological perturbations

    SciTech Connect

    Pitrou, Cyril; Uzan, Jean-Philippe; Bernardeau, Francis E-mail: uzan@iap.fr

    2010-07-01

    This article presents the first computation of the complete bispectrum of the cosmic microwave background temperature anisotropies arising from the evolution of all cosmic fluids up to second order, including neutrinos. Gravitational couplings, electron density fluctuations and the second order Boltzmann equation are fully taken into account. Comparison to limiting cases that appeared previously in the literature are provided. These are regimes for which analytical insights can be given. The final results are expressed in terms of equivalent f{sub NL} for different configurations. It is found that for moments up to l{sub max} = 2000, the signal generated by non-linear effects is equivalent to f{sub NL} ≅ 5 for both local-type and equilateral-type primordial non-Gaussianity.

  1. The Spectrum of the Cosmic X-ray Background Observed by RTXE/PCA

    NASA Technical Reports Server (NTRS)

    Revnivtsev, M.; Gilfanov, M.; Sunyaev, R.; Jahoda, K.; Markwardt, C.

    2004-01-01

    We have analyzed a large set of Rossi X-ray Timing Explorer/Proportional Counter Array (RXTE/PCA) scanning and slewing observations performed between April 1996 and March 1999. We obtained the 3-20 keV spectrum of the cosmic X-ray background (CXB) by subtracting Earth-occulted observations from observations of the X-ray sky at high galactic latitude and far away from sources. The sky coverage is approximately 22.6 x 10(exp 3) square degrees. The PCA spectrum of CXB in 3-20 keV energy band is adequately approximated by a single power law with photon index GAMMA approximately 1.4 and normalization at 1 keV approximately 9.5 phot/s/square centimeter/keV/sr. Instrumental background uncertainty precludes accurate RXTE/PCA measurements of the spectrum of cosmic X-ray background at energies above 15 keV and therefore we cannot detect the high energy cutoff observed by the High Energy Astronomical Observatory (HEAO)-1 A2 experiment. Deep observations of the 6 high latitude points used to model the PCA background provide a coarse measure of the spatial variation of the CXB. The CXB variations are consistent with a fixed spectral shape and variable normalization characterized by a fractional rms amplitude of approximately 7% on angular scales of approximately 1 square deg.

  2. Measuring the Cosmic X-ray Background With RXTE Using Lunar Occultation

    NASA Astrophysics Data System (ADS)

    Markwardt, Craig; Jahoda, K.; Marshall, F.; Strohmayer, T.; Swank, J.

    2011-09-01

    The Cosmic X-ray background (CXB) contains significant information about the energy content of the universe. However, the total X-ray background flux itself is still a matter of some controversy. A recent compilation of 10 CXB 2-10 keV flux measurements by Moretti et al. (2003) found statistical errors of 5%, with some values differing by up to 25%. Here we present preliminary results of a new technique to measure the X-ray background, using the dark side of the moon as an occulting shutter within the RXTE PCA field of view. This technique has the benefit of measuring the total X-ray background emission, rather than concentrating on the point-like sources. Observations were carefully designed to allow the moon to pass over the center of the PCA field of view, obscuring about 20% of the total field of view. Multiple observations throughout the year 2010, at different celestial locations, allow improved statistics and a measure of cosmic variance. In this work, we show the first results from this technique and compare to previous results, with the goal of achieving better than 5% statistical errors in the 2-10 keV band.

  3. Stochastic background from cosmic (super)strings: Popcorn-like and (Gaussian) continuous regimes

    NASA Astrophysics Data System (ADS)

    Regimbau, Tania; Giampanis, Stefanos; Siemens, Xavier; Mandic, Vuk

    2012-03-01

    In the era of the next generation of gravitational wave experiments a stochastic background from cusps of cosmic (super)strings is expected to be probed and, if not detected, to be significantly constrained. A popcornlike background can be, for part of the parameter space, as pronounced as the (Gaussian) continuous contribution from unresolved sources that overlap in frequency and time. We study both contributions from unresolved cosmic string cusps over a range of frequencies relevant to ground based interferometers, such as the LIGO/Virgo second generation and Einstein Telescope third generation detectors, the space antenna LISA, and pulsar timing arrays. We compute the sensitivity (at the 2σ level) in the parameter space for the LIGO/Virgo second generation detector, the Einstein Telescope detector, LISA, and pulsar timing arrays. We conclude that the popcorn regime is complementary to the continuous background. Its detection could therefore enhance confidence in a stochastic background detection and possibly help determine fundamental string parameters such as the string tension and the reconnection probability.

  4. A search for the dipole anisotropy of the Cosmic x ray background. Thesis

    NASA Technical Reports Server (NTRS)

    Evans, Tom

    1992-01-01

    X ray data was analyzed which was obtained by the HEAO-1 A2 satellite in order to look for large scale structure in the Cosmic X ray Background. The dipole moment of the x ray background is deltaI/I = (1.87 + or - .34)x 10(exp -2) in a direction, declination = 3.6 + or - 9.4 deg and right ascension = 15.9 + or - .2 hr. This implies a velocity of the Earth with respect to the background of 409.2 + or - 74.4 km/s in the same direction. Comparatively, measurements of the dipole anisotropy of the Cosmic Microwave Background imply a velocity of 369.2 + or - 4 km/s in a direction, declination = 6 + or - 1 deg and right ascension = 11.2 + or - .1 hr. Quoted errors are statistical only. The disparity between the velocities of the x ray dipole and microwave dipole may be due to residual structure in the x ray sky or as yet undiscovered systematic errors.

  5. COSMIC: A high resolution, large collecting area telescope. [Coherent Optical System of Modular Imaging Collectors (COSMIC)

    NASA Technical Reports Server (NTRS)

    Traub, W. A.; Carleton, N. P.

    1985-01-01

    The spaceborne Coherent Optical System of Modular Imaging Collectors (COSMIC) is presented. It has high angular resolution and can produce images of complex, low-surface-brightness objects such as distant galaxies. If configured as a 36 m filled linear array, COSMIC can have 15 times better angular resolution and 10 times greater collecting area than the Space Telescope. Alternatively, if the collecting area is spread out to create an unfilled two-dimensional array, there is the additional advantage of not needing to rotate the array in order to build up a reconstructed image. Considerations which led to the design concept, scientific goals, and the potentially useful role of a space station for assembly are discussed.

  6. Novel approach to imaging by cosmic-ray muons

    NASA Astrophysics Data System (ADS)

    Bikit, Istvan; Mrdja, Dusan; Bikit, Kristina; Slivka, Jaroslav; Jovancevic, Nikola; Oláh, László; Hamar, Gergő; Varga, Dezső

    2016-03-01

    Cosmic-ray muons can be used for imaging of large structures, or high-density objects with high atomic number. The first task can be performed by measurement of muon absorption within very thick material layers, while the second approach is based on muon multiple scattering. However, the muon imaging of small structures with low atomic number and density was not yet solved appropriately. Here we show the first results of cosmic-ray muon imaging of small objects made of elements of low atomic number. This novel approach includes detection of secondary particles produced by muons, which were not used at all in previous muon imaging methods. Thus, the list of elements, as well as the range of dimensions of objects which can be imaged are significantly expanded.

  7. Angular power spectrum of the FASTICA cosmic microwave background component from Background Emission Anisotropy Scanning Telescope data

    NASA Astrophysics Data System (ADS)

    Donzelli, S.; Maino, D.; Bersanelli, M.; Childers, J.; Figueiredo, N.; Lubin, P. M.; Meinhold, P. R.; O'Dwyer, I. J.; Seiffert, M. D.; Villela, T.; Wandelt, B. D.; Wuensche, C. A.

    2006-06-01

    We present the angular power spectrum of the cosmic microwave background (CMB) component extracted with FASTICA from the Background Emission Anisotropy Scanning Telescope (BEAST) data. BEAST is a 2.2-m off-axis telescope with a focal plane comprising eight elements at Q (38-45 GHz) and Ka (26-36 GHz) bands. It operates from the UC (University of California) White Mountain Research Station at an altitude of 3800 m. The BEAST CMB angular power spectrum has already been calculated by O'Dwyer et al. using only the Q-band data. With two input channels, FASTICA returns two possible independent components. We found that one of these two has an unphysical spectral behaviour, while the other is a reasonable CMB component. After a detailed calibration procedure based on Monte Carlo (MC) simulations, we extracted the angular power spectrum for the identified CMB component and found a very good agreement with the already published BEAST CMB angular power spectrum and with the Wilkinson Microwave Anisotropy Probe (WMAP) data.

  8. Constraining primordial black-hole bombs through spectral distortions of the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Pani, Paolo; Loeb, Abraham

    2013-08-01

    We consider the imprint of super-radiant instabilities of nonevaporating primordial black holes (PBHs) on the spectrum of the cosmic microwave background (CMB). In the radiation-dominated era, PBHs are surrounded by a roughly homogeneous cosmic plasma which endows photons with an effective mass through the plasma frequency. In this setting, spinning PBHs are unstable to a spontaneous spindown through the well-known “black hole bomb” mechanism. At the linear level, the photon density is trapped by the effective photon mass and grows exponentially in time due to super-radiance. As the plasma density declines due to cosmic expansion, the associated energy around PBHs is released and dissipated in the CMB. We evaluate the resulting spectral distortions of the CMB in the redshift range 103≲z≲2×106. Using the existing COBE/FIRAS bounds on CMB spectral distortions, we derive upper limits on the fraction of dark matter that can be associated with spinning PBHs in the mass range 10-8M⊙≲M≲0.2M⊙. For maximally spinning PBHs, our limits are much tighter than those derived from microlensing or other methods. Future data from the proposed PIXIE mission could improve our limits by several orders of magnitude.

  9. B polarization of the cosmic microwave background as a tracer of strings

    SciTech Connect

    Seljak, Uros; Slosar, Anze

    2006-09-15

    String models can produce successful inflationary scenarios in the context of brane collisions, and in many of these models cosmic strings may also be produced. In scenarios such as Kachru-Kallosh-Linde-Maldacena-McAllister-Trivedi (KKLMMT) scenario the string contribution is naturally predicted to be well below the inflationary signal for cosmic microwave background (CMB) temperature anisotropies, in agreement with the existing limits. We find that for B type polarization of CMB the situation is reversed and the dominant signal comes from vector modes generated by cosmic strings, which exceeds the gravity wave signal from both inflation and strings. The signal can be detected for a broad range of parameter space; future polarization experiments may be able to detect the string signal down to the string tension G{mu}=10{sup -9}, although foregrounds and lensing are likely to worsen these limits. We argue that the optimal scale to search for the string signature is at l{approx}1000, but in models with high optical depth the signal from reionization peak at large scales is also significant. The shape of the power spectrum allows one to distinguish the string signature from the gravity waves from inflation, but only with a sufficiently high angular resolution experiment.

  10. Taking the Universe's Temperature with Spectral Distortions of the Cosmic Microwave Background.

    PubMed

    Hill, J Colin; Battaglia, Nick; Chluba, Jens; Ferraro, Simone; Schaan, Emmanuel; Spergel, David N

    2015-12-31

    The cosmic microwave background (CMB) energy spectrum is a near-perfect blackbody. The standard model of cosmology predicts small spectral distortions to this form, but no such distortion of the sky-averaged CMB spectrum has yet been measured. We calculate the largest expected distortion, which arises from the inverse Compton scattering of CMB photons off hot, free electrons, known as the thermal Sunyaev-Zel'dovich (TSZ) effect. We show that the predicted signal is roughly one order of magnitude below the current bound from the COBE-FIRAS experiment, but it can be detected at enormous significance (≳1000σ) by the proposed Primordial Inflation Explorer (PIXIE). Although cosmic variance reduces the effective signal-to-noise ratio to 230σ, this measurement will still yield a subpercent constraint on the total thermal energy of electrons in the observable Universe. Furthermore, we show that PIXIE can detect subtle relativistic effects in the sky-averaged TSZ signal at 30σ, which directly probe moments of the optical depth-weighted intracluster medium electron temperature distribution. These effects break the degeneracy between the electron density and the temperature in the mean TSZ signal, allowing a direct inference of the mean baryon density at low redshift. Future spectral distortion probes will thus determine the global thermodynamic properties of ionized gas in the Universe with unprecedented precision. These measurements will impose a fundamental "integral constraint" on models of galaxy formation and the injection of feedback energy over cosmic time. PMID:26764983

  11. Deciphering inflation with gravitational waves: Cosmic microwave background polarization vs direct detection with laser interferometers

    SciTech Connect

    Smith, Tristan L.; Peiris, Hiranya V.; Cooray, Asantha

    2006-06-15

    A detection of the primordial gravitational wave background is considered to be the 'smoking-gun' evidence for inflation. While superhorizon waves are probed with cosmic microwave background (CMB) polarization, the relic background will be studied with laser interferometers. The long lever arm spanned by the two techniques improves constraints on the inflationary potential and validation of consistency relations expected under inflation. If gravitational waves with a tensor-to-scalar amplitude ratio greater than 0.01 are detected by the CMB, then a direct-detection experiment with a sensitivity consistent with current concept studies should be pursued vigorously. If no primordial tensors are detected by the CMB, a direct-detection experiment to understand the simplest form of inflation must have a sensitivity improved by two to 3 orders of magnitude over current plans.

  12. The Distortion of the Cosmic Microwave Background Spectrum Due to Intergalactic Dust

    NASA Astrophysics Data System (ADS)

    Imara, Nia; Loeb, Abraham

    2016-07-01

    Infrared emission from intergalactic dust might compromise the ability of future experiments to detect subtle spectral distortions in the Cosmic Microwave Background (CMB) from the early universe. We provide the first estimate of foreground contamination of the CMB signal due to diffuse dust emission in the intergalactic medium. We use models of the extragalactic background light to calculate the intensity of intergalactic dust emission and find that emission by intergalactic dust at z ≲ 0.5 exceeds the sensitivity of the planned Primordial Inflation Explorer to CMB spectral distortions by 1–3 orders of magnitude. In the frequency range ν = 150–2400 GHz, we place an upper limit of 0.06% on the contribution to the far-infrared background from intergalactic dust emission.

  13. Boltzmann hierarchy for the cosmic microwave background at second order including photon polarization

    SciTech Connect

    Beneke, M.; Fidler, C.

    2010-09-15

    Non-Gaussianity and B-mode polarization are particularly interesting features of the cosmic microwave background, as--at least in the standard model of cosmology--their only sources to first order in cosmological perturbation theory are primordial, possibly generated during inflation. If the primordial sources are small, the question arises how large is the non-Gaussianity and B-mode background induced in second order from the initially Gaussian and scalar perturbations. In this paper we derive the Boltzmann hierarchy for the microwave background photon phase-space distributions at second order in cosmological perturbation theory including the complete polarization information, providing the basis for further numerical studies. As an aside we note that the second-order collision term contains new sources of B-mode polarization and that no polarization persists in the tight-coupling limit.

  14. Signal/background classification in a cosmic ray space experiment by a modular neural system

    NASA Astrophysics Data System (ADS)

    Bellotti, Roberto; Castellano, Marcello; De Marzo, Carlo N.; Satalino, Giuseppe

    1995-04-01

    In the cosmic ray space experiments, the separation of the signal from background is a hard task. Due to the well-known critical conditions that characterize this class of experiments, some changes of the detector performances can be observed during the data taking. As a consequence, differences between the test and real data are found as systematic errors in the classification phase. In this paper, a modular classification system based on neural networks is proposed for the signal/background discrimination task in cosmic ray space experiments, without a priori knowledge of the discriminating feature distributions. The system is composed by two neural modules. The first one is a self organizing map (SOM) that both clusters the real data space in suitable classes of similarity and builds a prototype for each of them; a skilled inspection of the prototypes defines the signal and background. The second one, a multi layer perceptron (MLP) with a single hidden layer, adapts the classification model based on training/test data to the real experimental conditions. The MLP synaptic weights adaptive formation takes into account the labelled real data set as defined in the first system-phase. The modular neural system has been applied in the context of TRAMP-Si experiment, performed on the NASA Balloon-Borne Magnet Facility, for the positron/proton discrimination.

  15. Constraints on universe models with cosmological constant from cosmic microwave background anisotropy

    SciTech Connect

    Sugiyama, Naoshi; Gouda, Naoteru; Sasaki, Misao Kyoto Univ., Uji )

    1990-12-01

    Thorough numerical calculations of the fluctuations in the cosmic microwave background radiation using the gauge-invariant formalism are carried out for various cosmological models with the cosmological constant. It is shown that a spatially flat cold dark matter-dominated universe of Omega(0) = 0.1 to about 0.4 and H(0) = 50 to about 100 km/s per Mpc with adiabatic perturbations has the possibility of giving the final answer to cosmological puzzles. It is also found that the introduction of the cosmological constant may revive pure baryonic universe models. 33 refs.

  16. A search for anisotrophy in the cosmic microwave background on intermediate angular scales

    NASA Technical Reports Server (NTRS)

    Alsop, D. C.; Cheng, E. S.; Clapp, A. C.; Cottingham, D. A.; Fischer, M. L.; Gundersen, J. O.; Kreysa, E.; Lange, A. E.; Lubin, P. M.; Meinhold, P. R.

    1992-01-01

    The results of a search for anisotropy in the cosmic microwave background on angular scales near 1 deg are presented. Observations were simultaneously performed in bands centered at frequencies of 6, 9, and 12 per cm with a multifrequency bolometric receiver mounted on a balloon-borne telescope. The statistical sensitivity of the data is the highest reported to date at this angular scale, which is of critical importance for understanding the formation of structure in the universe. Signals in excess of random were observed in the data. The experiment, data analysis, and interpretation are described.

  17. Cosmic Microwave Background radiation and the Planck Satellite at Jodrell Bank

    NASA Astrophysics Data System (ADS)

    Wilkinson, Althea

    2011-07-01

    The University of Manchester, through Jodrell Bank, was involved in the construction of the two lowest frequency channels of the Low Frequency Instrument (LFI) for the Planck satellite. We have had many years experience of building cryogenically cooled low-noise amplifiers for Cosmic Microwave background experiments on Tenerife, which gave us the heritage to be able to do the same for Planck. I will describe what the aim of the mission was, give a few details of the adventure that was our first involvement in a modern space project, and end with a taster of the astronomical results so far released.

  18. Constraints on neutrino-dark matter interactions from cosmic microwave background and large scale structure data

    SciTech Connect

    Serra, Paolo; Cooray, Asantha; Zalamea, Federico; Mangano, Gianpiero; Melchiorri, Alessandro

    2010-02-15

    We update a previous investigation of cosmological effects of a nonstandard interaction between neutrinos and dark matter. Parametrizing the elastic-scattering cross section between the two species as a function of the temperature of the Universe, the resulting neutrino-dark matter fluid has a nonzero pressure, which determines diffusion-damped oscillations in the matter power spectrum similar to the acoustic oscillations generated by the photon-baryon fluid. Using cosmic microwave background data in combination with large scale structure experiment results, we then put constraints on the fraction of the interacting dark matter component as well as on the corresponding opacity.

  19. 3 mm Anisotropy Measurement: On the Quadrupole Component in theCosmic Background Radiation

    SciTech Connect

    Lubin, Philip M.; Epstein, Gerald L.; Smoot, George F.

    1982-11-01

    We have mapped the large-scale anisotropy in the cosmic background radiation at 3 mm wavelength using a liquid-helium-cooled balloon-borne radiometer sensitive enough to detect the dipole in one gondola rotation (1 minute). Statistical errors on the dipole and quadrupole components are below 0.1 mK with less than 0.1 m K galactic contribution. We find a dipole consistent with previous measurements but disagree with recent quadrupole reports. The measurement is also useful in searching for spectral distortions.

  20. Ralph A. Alpher, Robert C. Herman, and the Cosmic Microwave Background Radiation

    NASA Astrophysics Data System (ADS)

    Alpher, Victor S.

    2012-09-01

    Much of the literature on the history of the prediction and discovery of the Cosmic Microwave Background Radiation (CMBR) is incorrect in some respects. I focus on the early history of the CMBR, from its prediction in 1948 to its measurement in 1964, basing my discussion on the published literature, the private papers of Ralph A. Alpher, and interviews with several of the major figures involved in the prediction and measurement of the CMBR. I show that the early prediction of the CMBR continues to be widely misunderstood.

  1. Feedhorn-Coupled Transition-Edge Superconducting Bolometer Arrays for Cosmic Microwave Background Polarimetry

    NASA Technical Reports Server (NTRS)

    Hubmayr, J.; Austermann, J.; Beall, J.; Becker, D.; Cho, H.-M.; Datta, R.; Duff, S. M.; Grace, E.; Halverson, N.; Henderson, S. W.; Hilton, G. C.; Ho, S. P.; Irwin, K. D.; Koopman, B. J.; Li, D.; McMahon, J.; Munson, C.; Niemack, M. D.; Pappas, C.; Schmitt, B. L.; Simon, S. M.; Staggs, S. T.; Van Lanen, J.; Wollack, Edward J.

    2015-01-01

    NIST produces large-format, dual-polarization-sensitive detector arrays for a broad range of frequencies (30-1400 GHz). Such arrays enable a host of astrophysical measurements. Detectors optimized for cosmic microwave background observations are monolithic, polarization-sensitive arrays based on feedhorn and planar Nb antenna-coupled transition-edge superconducting (TES) bolometers. Recent designs achieve multiband, polarimetric sensing within each spatial pixel. In this proceeding, we describe our multichroic, feedhorn-coupled design; demonstrate performance at 70-380 GHz; and comment on current developments for implementation of these detector arrays in the advanced Atacama Cosmology Telescope receiver

  2. Probing the Light Speed Anisotropy with Respect to the Cosmic Microwave Background Radiation Dipole

    NASA Astrophysics Data System (ADS)

    Gurzadyan, V. G.; Bocquet, J.-P.; Kashin, A.; Margarian, A.; Bartalini, O.; Bellini, V.; Castoldi, M.; D'Angelo, A.; Didelez, J.-P.; di Salvo, R.; Fantini, A.; Gervino, G.; Ghio, F.; Girolami, B.; Giusa, A.; Guidal, M.; Hourany, E.; Knyazyan, S.; Kouznetsov, V.; Kunne, R.; Lapik, A.; Levi Sandri, P.; Lleres, A.; Mehrabyan, S.; Moricciani, D.; Nedorezov, V.; Perrin, C.; Rebreyend, D.; Russo, G.; Rudnev, N.; Schaerf, C.; Sperduto, M.-L.; Sutera, M.-C.; Turinge, A.

    We have studied the angular fluctuations in the speed of light with respect to the apex of the dipole of Cosmic Microwave Background (CMB) radiation using the experimental data obtained with GRAAL facility, located at the European Synchrotron Radiation Facility (ESRF) in Grenoble. The measurements were based on the stability of the Compton edge of laser photons scattered on the 6 GeV monochromatic electron beam. The results enable one to obtain a conservative constraint on the anisotropy in the light speed variations Δc(θ)/c<3×10-12, i.e. with higher precision than from previous experiments.

  3. Minkowski functionals used in the morphological analysis of cosmic microwave background anisotropy maps

    NASA Astrophysics Data System (ADS)

    Schmalzing, Jens; Gorski, Krzysztof M.

    1998-06-01

    We present a novel approach to quantifying the morphology of cosmic microwave background (CMB) anisotropy maps. As morphological descriptors, we use shape parameters known as Minkowski functionals. Using the mathematical framework provided by the theory of integral geometry on arbitrary curved supports, we point out the differences in their characterization and interpretation in the case of flat space. With the restrictions of real data - such as pixelization and incomplete sky coverage, to mention just a few - in mind, we derive and test unbiased estimators for all Minkowski functionals. Various examples, among them the analysis of the four-year COBE DMR data, illustrate the application of our method.

  4. Cosmological Implications of the Effects of X-Ray Clusters on the Cosmic Microwave Background

    NASA Technical Reports Server (NTRS)

    Forman, William R.

    1996-01-01

    We have been carrying forward a program to confront X-ray observations of clusters and their evolution as derived from X-ray observatories with observations of the cosmic microwave background radiation (CMBR). In addition to the material covered in our previous reports (including three published papers), most recently we have explored the effects of a cosmological constant on the predicted Sunyaev-Zel'dovich effect from the ensemble of clusters. In this report we summarize that work from which a paper will be prepared.

  5. A search for anisotrophy in the cosmic microwave background on intermediate angular scales

    NASA Astrophysics Data System (ADS)

    Alsop, D. C.; Cheng, E. S.; Clapp, A. C.; Cottingham, D. A.; Fischer, M. L.; Gundersen, J. O.; Kreysa, E.; Lange, A. E.; Lubin, P. M.; Meinhold, P. R.; Richards, P. L.; Smoot, G. F.

    1992-08-01

    The results of a search for anisotropy in the cosmic microwave background on angular scales near 1 deg are presented. Observations were simultaneously performed in bands centered at frequencies of 6, 9, and 12 per cm with a multifrequency bolometric receiver mounted on a balloon-borne telescope. The statistical sensitivity of the data is the highest reported to date at this angular scale, which is of critical importance for understanding the formation of structure in the universe. Signals in excess of random were observed in the data. The experiment, data analysis, and interpretation are described.

  6. South Pole studies of the anisotropy of the cosmic background radiation at one degree

    SciTech Connect

    Meinhold, P.R.; Lubin, P.M.; Chingcuanco, A.O.; Schuster, J.A.; Seiffert, M. )

    1990-01-15

    We have developed a system for making measurements of spatial fluctuations in the Cosmic Microwave Background Radiation at 3 mm wavelength, on an angular scale of .5 to 5 degrees. The system includes a telescope with a Gaussian beam with a full width at half max (FWHM) of 20 to 50 arc-minutes, an SIS (Superconductor-Insulator-Superconductor) coherent receiver operating around 90 GHz, and for ballon flights, a pointing system capable of 1 arc-minute RMS stabilization. We report on results from ground based measurments made from the South Pole station during Decmeber, 1988.

  7. Global universe anisotropy probed by the alignment of structures in the cosmic microwave background.

    PubMed

    Wiaux, Y; Vielva, P; Martínez-González, E; Vandergheynst, P

    2006-04-21

    We question the global universe isotropy by probing the alignment of local structures in the cosmic microwave background (CMB) radiation. The original method proposed relies on a steerable wavelet decomposition of the CMB signal on the sphere. The analysis of the first-year Wilkinson Microwave Anisotropy Probe data identifies a mean preferred plane with a normal direction close to the CMB dipole axis, and a mean preferred direction in this plane, very close to the ecliptic poles axis. Previous statistical anisotropy results are thereby synthesized, but further analyses are still required to establish their origin. PMID:16712146

  8. Enhanced polarization of the cosmic microwave background radiation from thermal gravitational waves.

    PubMed

    Bhattacharya, Kaushik; Mohanty, Subhendra; Nautiyal, Akhilesh

    2006-12-22

    If inflation was preceded by a radiation era, then at the time of inflation there will exist a decoupled thermal distribution of gravitons. Gravitational waves generated during inflation will be amplified by the process of stimulated emission into the existing thermal distribution of gravitons. Consequently, the usual zero temperature scale invariant tensor spectrum is modified by a temperature dependent factor. This thermal correction factor amplifies the B-mode polarization of the cosmic microwave background radiation by an order of magnitude at large angles, which may now be in the range of observability of the Wilkinson Microwave Anisotropy Probe. PMID:17280339

  9. Efficient decomposition of cosmic microwave background polarization maps into pure E, pure B, and ambiguous components

    SciTech Connect

    Bunn, Emory F.

    2011-04-15

    Separation of the B component of a cosmic microwave background (CMB) polarization map from the much larger E component is an essential step in CMB polarimetry. For a map with incomplete sky coverage, this separation is necessarily hampered by the presence of ambiguous modes which could be either E or B modes. I present an efficient pixel-space algorithm for removing the ambiguous modes and separating the map into pure E and B components. The method, which works for arbitrary geometries, does not involve generating a complete basis of such modes and scales the cube of the number of pixels on the boundary of the map.

  10. New 33 GHz Measurements of the Cosmic Background RadiationIntensity

    SciTech Connect

    De Amici, G.; Smoot, G.; Friedman, S.G.; Witebsky, C.

    1985-03-01

    New measurements have been made of the intensity of the cosmic background radiation (CBR) at 33 GHz (0.91 cm). The experiment was part of a larger effort to measure the spectrum of the CBR between 2.5 and 90 GHz (12 and 0.33 cm). Details are given of the experimental equipment and measurement procedures. The results of measurements made in 1982 and 1983 are presented and discussed in relation to preliminary results from the other radiometers. The measured value, T{sub CBR} = (2.81 {+-} 0.12) K, is in very good agreement both with those previously published and those reported by our collaborators.

  11. Cosmic gamma-ray background from structure formation in the intergalactic medium

    PubMed

    Loeb; Waxman

    2000-05-11

    The Universe is filled with a diffuse background of gamma-ray radiation, the origin of which remains one of the unsolved puzzles of cosmology. Less than one-quarter of the gamma-ray flux can be attributed to unresolved discrete sources, such as active galactic nuclei; the remainder appears to constitute a truly diffuse background. Here we show that the shock waves induced by gravity in the gas of the intergalactic medium, during the formation of large-scale structures like filaments and sheets of galaxies, produce a population of highly relativistic electrons. These electrons scatter a small fraction of the cosmic microwave background photons in the local Universe up to gamma-ray energies, thereby providing the gamma-ray background. The predicted diffuse flux agrees with the observed background across more than four orders of magnitude in photon energy, and the model predicts that the gamma-ray background, though generated locally, is isotropic to better than five per cent on angular scales larger than a degree. Moreover, the agreement between the predicted and observed background fluxes implies a mean cosmological density of baryons that is consistent with Big Bang nucleosynthesis. PMID:10821264

  12. Cosmological Constant or Intergalactic Dust? Constraints from the Cosmic Far-Infrared Background

    SciTech Connect

    Aguirre, Anthony; Haiman, Zoltan

    2000-03-20

    Recent observations of Type Ia supernovae (SNe) at redshifts 0cosmic UV/optical background radiation around {approx}1 {mu}m, and reemits it at far-infrared (FIR) wavelengths. Here we compare the FIR emission from IG dust with observations of the cosmic microwave (CMB) and cosmic far-infrared backgrounds (FIRB) by the DIRBE/FIRAS instruments. We find that the emission would not lead to measurable distortion of the CMB, but would represent a substantial fraction ((greater-or-similar sign)75%) of the measured value of the FIRB in the 300-1000 {mu}m range. This contribution would be marginally consistent with the present unresolved fraction of the observed FIRB in an open universe. However, we find that IG dust probably could not reconcile the standard {omega}=1 CDM model with the SN observations, even if the necessary quantity of dust existed. Future observations, capable of reliably resolving the FIRB to a flux limit of {approx}0.5 mJy, along with a more precise measure of the coarse-grained FIRB, will provide a definitive test of the IG dust hypothesis in all cosmologies. (c) 2000 The American Astronomical Society.

  13. Large-angle cosmic microwave background anisotropies in an open universe

    NASA Technical Reports Server (NTRS)

    Kamionkowski, Marc; Spergel, David N.

    1994-01-01

    If the universe is open, scales larger than the curvature scale may be probed by observation of large-angle fluctuations in the cosmic microwave background (CMB). We consider primordial adiabatic perturbations and discuss power spectra that are power laws in volume, wavelength, and eigenvalue of the Laplace operator. Such spectra may have arisen if, for example, the universe underwent a period of `frustated' inflation. The resulting large-angle anisotropies of the CMB are computed. The amplitude generally increases as Omega is decreased but decreases as h is increased. Interestingly enough, for all three Ansaetze, anisotropies on angular scales larger than the curvature scale are suppressed relative to the anisotropies on scales smaller than the curvature scale, but cosmic variance makes discrimination between various models difficult. Models with 0.2 approximately less than Omega h approximately less than 0.3 appear compatible with CMB fluctuations detected by Cosmic Background Explorer Satellite (COBE) and the Tenerife experiment and with the amplitude and spectrum of fluctuations of galaxy counts in the APM, CfA, and 1.2 Jy IRAS surveys. COBE normalization for these models yields sigma(sub 8) approximately = 0.5 - 0.7. Models with smaller values of Omega h when normalized to COBE require bias factors in excess of 2 to be compatible with the observed galaxy counts on the 8/h Mpc scale. Requiring that the age of the universe exceed 10 Gyr implies that Omega approximately greater than 0.25, while requiring that from the last-scattering term in the Sachs-Wolfe formula, large-angle anisotropies come primarily from the decay of potential fluctuations at z approximately less than 1/Omega. Thus, if the universe is open, COBE has been detecting temperature fluctuations produced at moderate redshift rather than at z approximately 1300.

  14. Multiple flare-angle horn feeds for sub-mm astronomy and cosmic microwave background experiments

    NASA Astrophysics Data System (ADS)

    Leech, J.; Tan, B. K.; Yassin, G.; Kittara, P.; Wangsuya, S.; Treuttel, J.; Henry, M.; Oldfield, M. L.; Huggard, P. G.

    2011-08-01

    Context. The use of large-format focal plane imaging arrays employing multiple feed horns is becoming increasingly important for the next generation of single dish sub-mm telescopes and cosmology experiments. Such receivers are being commissioned on both general purpose, common user telescopes and telescopes specifically designed for mapping intensity and polarisation anisotropies in the cosmic microwave background (CMB). Telescopes are currently being constructed to map the CMB polarisation that employ hundreds of feeds and the cost of manufacturing these feeds has become a significant fraction of the total cost of the telescope. Aims: We have developed and manufactured low-cost easy-to-machine smooth-walled horns that have a performance comparable to the more traditional corrugated feed horns that are often used in focal plane arrays. Our horns are much easier to fabricate than corrugated horns enabling the rapid construction of arrays with a large number of horns at a very low cost. Methods: Our smooth walled horns use multiple changes in flare angle to excite higher order waveguide modes. They are designed using a genetic algorithm to optimise the positions and magnitudes of these flare angle discontinuities. We have developed a fully parallelised software suite for the optimisation of these horns. We have manufactured prototype horns by traditional electroforming and also by a new direct drilling technique and we have measured their beam patterns using a far-field antenna test range at 230 GHz. Results: We present simulated and measured far-field beam patterns for one of our horn designs. They exhibit low sidelobe levels, good beam circularity and low cross-polarisation levels over a fractional bandwidth of 20%. These results offer experimental confirmation of our design technique, allowing us to proceed confidently in the optimisation of horns with a wider operational bandwidth. The results also show that the new manufacturing technique using drilling is

  15. SECOND SEASON QUIET OBSERVATIONS: MEASUREMENTS OF THE COSMIC MICROWAVE BACKGROUND POLARIZATION POWER SPECTRUM AT 95 GHz

    SciTech Connect

    Araujo, D.; Dumoulin, R. N.; Newburgh, L. B.; Zwart, J. T. L.; Bischoff, C.; Brizius, A.; Buder, I.; Kusaka, A.; Chinone, Y.; Cleary, K.; Reeves, R.; Naess, S. K.; Eriksen, H. K.; Wehus, I. K.; Bronfman, L.; Church, S. E.; Dickinson, C.; Gaier, T.; Collaboration: QUIET Collaboration; and others

    2012-12-01

    The Q/U Imaging ExperimenT (QUIET) has observed the cosmic microwave background (CMB) at 43 and 95 GHz. The 43 GHz results have been published in a previous paper, and here we report the measurement of CMB polarization power spectra using the 95 GHz data. This data set comprises 5337 hr of observations recorded by an array of 84 polarized coherent receivers with a total array sensitivity of 87 {mu}K{radical}s. Four low-foreground fields were observed, covering a total of {approx}1000 deg{sup 2} with an effective angular resolution of 12.'8, allowing for constraints on primordial gravitational waves and high signal-to-noise measurements of the E-modes across three acoustic peaks. The data reduction was performed using two independent analysis pipelines, one based on a pseudo-C {sub l} (PCL) cross-correlation approach, and the other on a maximum-likelihood (ML) approach. All data selection criteria and filters were modified until a predefined set of null tests had been satisfied before inspecting any non-null power spectrum. The results derived by the two pipelines are in good agreement. We characterize the EE, EB, and BB power spectra between l = 25 and 975 and find that the EE spectrum is consistent with {Lambda}CDM, while the BB power spectrum is consistent with zero. Based on these measurements, we constrain the tensor-to-scalar ratio to r = 1.1{sup +0.9} {sub -0.8} (r < 2.8 at 95% C.L.) as derived by the ML pipeline, and r = 1.2{sup +0.9} {sub -0.8} (r < 2.7 at 95% C.L.) as derived by the PCL pipeline. In one of the fields, we find a correlation with the dust component of the Planck Sky Model, though the corresponding excess power is small compared to statistical errors. Finally, we derive limits on all known systematic errors, and demonstrate that these correspond to a tensor-to-scalar ratio smaller than r = 0.01, the lowest level yet reported in the literature.

  16. Second Season QUIET Observations: Measurements of the Cosmic Microwave Background Polarization Power Spectrum at 95 GHz

    NASA Astrophysics Data System (ADS)

    QUIET Collaboration; Araujo, D.; Bischoff, C.; Brizius, A.; Buder, I.; Chinone, Y.; Cleary, K.; Dumoulin, R. N.; Kusaka, A.; Monsalve, R.; Næss, S. K.; Newburgh, L. B.; Reeves, R.; Wehus, I. K.; Zwart, J. T. L.; Bronfman, L.; Bustos, R.; Church, S. E.; Dickinson, C.; Eriksen, H. K.; Gaier, T.; Gundersen, J. O.; Hasegawa, M.; Hazumi, M.; Huffenberger, K. M.; Ishidoshiro, K.; Jones, M. E.; Kangaslahti, P.; Kapner, D. J.; Kubik, D.; Lawrence, C. R.; Limon, M.; McMahon, J. J.; Miller, A. D.; Nagai, M.; Nguyen, H.; Nixon, G.; Pearson, T. J.; Piccirillo, L.; Radford, S. J. E.; Readhead, A. C. S.; Richards, J. L.; Samtleben, D.; Seiffert, M.; Shepherd, M. C.; Smith, K. M.; Staggs, S. T.; Tajima, O.; Thompson, K. L.; Vanderlinde, K.; Williamson, R.

    2012-12-01

    The Q/U Imaging ExperimenT (QUIET) has observed the cosmic microwave background (CMB) at 43 and 95 GHz. The 43 GHz results have been published in a previous paper, and here we report the measurement of CMB polarization power spectra using the 95 GHz data. This data set comprises 5337 hr of observations recorded by an array of 84 polarized coherent receivers with a total array sensitivity of 87 μK\\sqrt{s}. Four low-foreground fields were observed, covering a total of ~1000 deg2 with an effective angular resolution of 12farcm8, allowing for constraints on primordial gravitational waves and high signal-to-noise measurements of the E-modes across three acoustic peaks. The data reduction was performed using two independent analysis pipelines, one based on a pseudo-C l (PCL) cross-correlation approach, and the other on a maximum-likelihood (ML) approach. All data selection criteria and filters were modified until a predefined set of null tests had been satisfied before inspecting any non-null power spectrum. The results derived by the two pipelines are in good agreement. We characterize the EE, EB, and BB power spectra between l = 25 and 975 and find that the EE spectrum is consistent with ΛCDM, while the BB power spectrum is consistent with zero. Based on these measurements, we constrain the tensor-to-scalar ratio to r = 1.1+0.9 - 0.8 (r < 2.8 at 95% C.L.) as derived by the ML pipeline, and r = 1.2+0.9 - 0.8 (r < 2.7 at 95% C.L.) as derived by the PCL pipeline. In one of the fields, we find a correlation with the dust component of the Planck Sky Model, though the corresponding excess power is small compared to statistical errors. Finally, we derive limits on all known systematic errors, and demonstrate that these correspond to a tensor-to-scalar ratio smaller than r = 0.01, the lowest level yet reported in the literature.

  17. The Cosmic Microwave Background Radiation - A Unique Window on the Early Universe

    NASA Technical Reports Server (NTRS)

    Hinshaw, Gary F.

    2009-01-01

    The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of approx. 1100. Data from the first five years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time.

  18. The Cosmic Microwave Background Radiation - A Unique Window on the Early Universe

    NASA Technical Reports Server (NTRS)

    Hinshaw, Gary F.

    2009-01-01

    The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of approximately 1100. Data from the first five years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. WMAP, part of NASA's Explorers program, was launched on June 30, 2001. The WMAP satellite was produced in a partnership between the Goddard Space Flight Center and Princeton University. The WMAP team also includes researchers at the Johns Hopkins University; the Canadian Institute of Theoretical Astrophysics; University of Texas; Oxford University; University of Chicago; Brown University; University of British Columbia; and University of California, Los Angeles.

  19. The Cosmic Microwave Background Radiation-A Unique Window on the Early Universe

    NASA Technical Reports Server (NTRS)

    Hinshaw, Gary

    2010-01-01

    The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of 11 00. Data from the first seven years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. WMAP, part of NASA's Explorers program, was launched on June 30, 2001. The WMAP satellite was produced in a partnership between the Goddard Space Flight Center and Princeton University. The WMAP team also includes researchers at the Johns Hopkins University; the Canadian Institute of Theoretical Astrophysics; University of Texas; Oxford University; University of Chicago; Brown University; University of British Columbia; and University of California, Los Angeles.

  20. The Cosmic Microwave Background Radiation - A Unique Window on the Early Universe

    NASA Technical Reports Server (NTRS)

    Hinshaw, Gary F.

    2008-01-01

    The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of approximately 1100. Data from the first five years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. WMAP, part of NASA's Explorers program, was launched on June 30, 2001. The WMAP satellite was produced in a partnership between the Goddard Space Flight Center and Princeton University. The WMAP team also includes researchers at Johns Hopkins University; the Canadian Institute of Theoretical Astrophysics; University of Texas; Oxford University; University of Chicago; Brown university; University of British Columbia; and University of California, Los Angeles.

  1. Looking for early black holes signatures in the anisotropies of Cosmic backgrounds

    NASA Astrophysics Data System (ADS)

    Cappelluti, Nico

    2016-04-01

    We currently do not know how Super Massive Black Holes are seeded and grow to form the observed massive QSO at z~7. This is puzzling, because at that redshift the Universe was still too young to allow the growth of such massive black holes from stellar remnant black hole seeds. Theoretical models, taking into account the paucity of metals in the early Universe, explain this by invoking the formation of massive black holes seeds at z>10 as Direct Collapse Black holes of remnants of dead POPIII stars. As of today we cannot claim any detection of any high-z (z>7) black hole in their early stage of life. However, our recent measures of the arcminute scale joint fluctuations of the Cosmic X-ray Background and the Cosmic Infrared Background by Chandra and Spitzer can be explained by a population of highly absorbed z>10 Direct Collapse Black Holes.I will review the recent discoveries obtained with different instruments and by different teams and critically discuss these findings and the interpretations.

  2. Relic right-handed Dirac neutrinos and implications for detection of cosmic neutrino background

    NASA Astrophysics Data System (ADS)

    Zhang, Jue; Zhou, Shun

    2016-02-01

    It remains to be determined experimentally if massive neutrinos are Majorana or Dirac particles. In this connection, it has been recently suggested that the detection of cosmic neutrino background of left-handed neutrinos νL and right-handed antineutrinos ν‾R in future experiments of neutrino capture on beta-decaying nuclei (e.g., νe +3H →3He +e- for the PTOLEMY experiment) is likely to distinguish between Majorana and Dirac neutrinos, since the capture rate is twice larger in the former case. In this paper, we investigate the possible impact of right-handed neutrinos on the capture rate, assuming that massive neutrinos are Dirac particles and both right-handed neutrinos νR and left-handed antineutrinos ν‾L can be efficiently produced in the early Universe. It turns out that the capture rate can be enhanced at most by 28% due to the presence of relic νR and ν‾L with a total number density of 95 cm-3, which should be compared to the number density 336 cm-3 of cosmic neutrino background. The enhancement has actually been limited by the latest cosmological and astrophysical bounds on the effective number of neutrino generations Neff =3.14-0.43+0.44 at the 95% confidence level. For illustration, two possible scenarios have been proposed for thermal production of right-handed neutrinos in the early Universe.

  3. A precise measurement of the cosmic microwave background temperature from optical observations of interstellar CN

    NASA Technical Reports Server (NTRS)

    Meyer, D. M.; Jura, M.

    1985-01-01

    Very precise observations (with S/N greater than 2000) of the 3874-angstrom band of interstellar CN toward zeta Per and omicron Per are presented. In the zeta Oph, zeta Per, and omicron Per lines of sight, the saturation-corrected CN line strengths yield respective excitation temperatures of 2.72 plus or minus 0.05 K, 2.76 plus or minus 0.05 K, and 2.78 plus or minus 0.07 K for the J = 0-1 rotational transition at 2.64 mm. By confirming the blackbody character of the cosmic microwave background spectrum at wavelengths near the peak of its flux, the simplest explanation of the background as primeval fireball radiation from a hot bang is reinforced.

  4. Science objectives lead to contamination requirements for the Cosmic Background Explorer (COBE)

    NASA Technical Reports Server (NTRS)

    Abrams, Eve M.; Carosso, Nancy J. P.

    1990-01-01

    The mission aims and related requirements of the Cosmic Background Explorer (COBE) are described in order to assess the measure needed for adequate control of optical system contamination. Instrument requirements are set forth so that the Diffuse IR Background Experiment (DIRBE), the Far IR Absolute Spectrophotometer (FIRAS), and the Differential Microwave Radiometers (DMRs) can achieve performance goals. The BRDF requirement for the primary mirror of the DIRBE is a maximum change of 50 percent on clean versus contaminated mirrors. The most critical components of the FIRAS and the DMR are discussed which are the sky horn and the antennae throats, respectively. The contamination-control devices include contamination covers, cleanroom assembly, and retractable cover assembly. The COBE is not found to perform unreliably due to contamination problems which suggests that the contamination program is effective.

  5. The Cosmic Microwave Background Anisotropy Power Spectrum from the BEAST Experiment

    NASA Astrophysics Data System (ADS)

    O'Dwyer, Ian J.; Bersanelli, Marco; Childers, Jeffrey; Figueiredo, Newton; Halevi, Doron; Huey, Greg; Lubin, Philip M.; Maino, Davide; Mandolesi, Nazzareno; Marvil, Joshua; Meinhold, Peter R.; Mejía, Jorge; Natoli, Paolo; O'Neill, Hugh; Pina, Agenor; Seiffert, Michael D.; Stebor, Nathan C.; Tello, Camilo; Villela, Thyrso; Wandelt, Benjamin D.; Williams, Brian; Wuensche, Carlos Alexandre

    2005-05-01

    The Background Emission Anisotropy Scanning Telescope (BEAST) is a 2.2 m off-axis telescope with an eight-element mixed Q-band (38-45 GHz) and Ka-band (26-36 GHz) focal plane, designed for balloon-borne and ground-based studies of the cosmic microwave background (CMB). Here we present the CMB angular power spectrum calculated from 682 hr of data observed with the BEAST instrument. We use a binned pseudo-Cl estimator (the MASTER method). We find results that are consistent with other determinations of the CMB anisotropy for angular wavenumbers l between 100 and 600. We also perform cosmological parameter estimation. The BEAST data alone produce a good constraint on Ωk≡1-Ωtot=-0.074+/-0.070, consistent with a flat universe. A joint parameter estimation analysis with a number of previous CMB experiments produces results consistent with previous determinations.

  6. Intensity Mapping of the History of Stellar Emission with the Cosmic Infrared Background ExpeRiment-2

    NASA Astrophysics Data System (ADS)

    Lanz, Alicia E.; Arai, Toshiaki; Battle, John; Bock, James; Cooray, Asantha R.; Hristov, Viktor; Korngut, Phillip; Lee, Dae Hee; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Onishi, Yosuke; Shirahata, Mai; Tsumurai, Kohji; Wada, Takehiko; Zemcov, Michael B.

    2016-01-01

    Recent measurements of the near-infrared Extragalactic Background Light (EBL) anisotropy find excess spatial power above the level predicted by known galaxy populations at large angular scales. These anisotropies trace spatial variations in integrated photon production, so measurements of EBL surface brightness fluctuations provide a complete census of the emission from stars summed over cosmic history. As a result, EBL fluctuations contain contributions from objects forming during the Epoch of Reionization (EOR), from the integrated galactic light (IGL), and faint, extended components such as intra-halo light (IHL) from stars tidally stripped from galaxies during merger events. Additional measurements with greater sensitivity, spectral range, and spectral resolution are required to disentangle these contributions.The Cosmic Infrared Background ExpeRiment 2 (CIBER-2) is an instrument optimized for the measurement of near-infrared EBL anisotropies. As the Earth's atmosphere generates time-varying near-infrared emission, CIBER-2 is launched on a sounding rocket from which it will carry out multiwavelength imaging in six spectral bands that span the visible to near-infrared. The 2.4 square degree images allow CIBER-2 to produce measurements of EBL fluctuations with high fidelity on large angular scales. The Lyman break feature from EOR sources provides a unique spectral feature which can be used to disentangle the high from the low redshift contributions to the anisotropy signal. Measurement in six independent wavebands allows detailed cross-correlation studies to constrain the source of the excess fluctuations at large angular scales. We provide an overview of the CIBER-2 instrument and explain CIBER-2 spectral feature identification and cross-correlation study methodologies.

  7. Gravitational waves from light cosmic strings: Backgrounds and bursts with large loops

    SciTech Connect

    Hogan, Craig J.

    2006-08-15

    The mean spectrum and burst statistics of gravitational waves produced by a cosmological population of cosmic string loops are estimated using analytic approximations, calibrated with earlier simulations. Formulas are derived showing the dependence of observables on the string tension G{mu}, in the regime where newly-formed loops are relatively large, not very much smaller than the horizon. Large loops form earlier, are more abundant, and generate a more intense stochastic background and more frequent bursts than assumed in earlier background estimates, enabling experiments to probe lighter cosmic strings of interest to string theory. Predictions are compared with instrument noise from current and future experiments, and with confusion noise from known astrophysical gravitational-wave sources such as stellar and massive black hole binaries. In these large-loop models, current data from millisecond pulsar timing already suggests that G{mu} is less than about 10{sup -10}, close to the minimum value where bursts might be detected by Advanced LIGO, and a typical value expected in strings from brane inflation. Because of confusion noise expected from massive black hole binaries, pulsar techniques will not be able to go below about G{mu}{approx_equal}10{sup -11}. LISA will be sensitive to stochastic backgrounds created by strings as light as G{mu}{approx_equal}10{sup -15}, at frequencies where it is limited by confusion noise of Galactic stellar populations; however, for those lightest detectable strings, bursts are rarely detectable. For G{mu}>10{sup -11}, the stochastic background from strings dominates the LISA noise by a large factor, and burst events may also be detectable by LISA, allowing detailed study of loop behavior. Astrophysical confusion might be low enough at 0.1 to 1 Hz to eventually reach G{mu}{approx_equal}10{sup -20} with future interferometer technology.

  8. Angular correlation of the cosmic microwave background in the Rh = ct Universe

    NASA Astrophysics Data System (ADS)

    Melia, F.

    2014-01-01

    Context. The emergence of several unexpected large-scale features in the cosmic microwave background (CMB) has pointed to possible new physics driving the origin of density fluctuations in the early Universe and their evolution into the large-scale structure we see today. Aims: In this paper, we focus our attention on the possible absence of angular correlation in the CMB anisotropies at angles larger than ~60°, and consider whether this feature may be the signature of fluctuations expected in the Rh = ct Universe. Methods: We calculate the CMB angular correlation function for a fluctuation spectrum expected from growth in a Universe whose dynamics is constrained by the equation-of-state p = -ρ/3, where p and ρ are the total pressure and density, respectively. Results: We find that, though the disparity between the predictions of ΛCDM and the WMAP sky may be due to cosmic variance, it may also be due to an absence of inflation. The classic horizon problem does not exist in the Rh = ct Universe, so a period of exponential growth was not necessary in this cosmology in order to account for the general uniformity of the CMB (save for the aforementioned tiny fluctuations of 1 part in 100 000 in the WMAP relic signal). Conclusions: We show that the Rh = ct Universe without inflation can account for the apparent absence in CMB angular correlation at angles θ ≳ 60° without invoking cosmic variance, providing additional motivation for pursuing this cosmology as a viable description of nature.

  9. What can be learned from the lensed cosmic microwave background B-mode polarization power spectrum?

    SciTech Connect

    Smith, Sarah; Challinor, Anthony; Rocha, Graca

    2006-01-15

    The effect of weak gravitational lensing on the cosmic microwave background (CMB) temperature anisotropies and polarization will provide access to cosmological information that cannot be obtained from the primary anisotropies alone. We compare the information content of the lensed B-mode polarization power spectrum, properly accounting for the non-Gaussian correlations between the power on different scales, with that of the unlensed CMB fields and the lensing potential. The latter represent the products of an (idealized) optimal analysis that exploits the lens-induced non-Gaussianity to reconstruct the fields. Compressing the non-Gaussian lensed CMB into power spectra is wasteful and leaves a tight degeneracy between the equation of state of dark energy and neutrino mass that is much stronger than in the more optimal analysis. Despite this, a power-spectrum analysis will be a useful first step in analyzing future B-mode polarization data. For this reason, we also consider how to extract accurate parameter constraints from the lensed B-mode power spectrum. We show with simulations that for cosmic-variance-limited measurements of the lensed B-mode power, including the non-Gaussian correlations in existing likelihood approximations gives biased parameter results. We develop a more refined likelihood approximation that performs significantly better. This new approximation should also be of more general interest in the wider context of parameter estimation from Gaussian CMB data.

  10. The effects of cosmic microwave background (CMB) temperature uncertainties on cosmological parameter estimation

    SciTech Connect

    Hamann, Jan; Wong, Yvonne Y Y E-mail: ywong@mppmu.mpg.de

    2008-03-15

    We estimate the effect of the experimental uncertainty in the measurement of the temperature of the cosmic microwave background (CMB) on the extraction of cosmological parameters from future CMB surveys. We find that even for an ideal experiment limited only by cosmic variance up to l=2500 for both the temperature and polarization measurements, the projected cosmological parameter errors are remarkably robust against the uncertainty of 1 mK in the firas CMB temperature monopole measurement. The maximum degradation in sensitivity is 20%, for the baryon density estimate, relative to the case in which the monopole is known infinitely well. While this degradation is acceptable, we note that reducing the uncertainty in the current temperature measurement by a factor of five will bring it down to {approx}1%. We also estimate the effect of the uncertainty in the dipole temperature measurement. Assuming the overall calibration of the data to be dominated by the dipole error of 0.2% from firas, the sensitivity degradation is insignificant and does not exceed 10% in any parameter direction.

  11. Inflation Physics from the Cosmic Microwave Background and Large Scale Structure

    NASA Technical Reports Server (NTRS)

    Abazajian, K.N.; Arnold,K.; Austermann, J.; Benson, B.A.; Bischoff, C.; Bock, J.; Bond, J.R.; Borrill, J.; Buder, I.; Burke, D.L.; Calabrese, E.; Carlstrom, J.E.; Carvalho, C.S.; Chang, C.L.; Chiang, H.C.; Church, S.; Cooray, A.; Crawford, T.M.; Crill, B.P.; Dawson, K.S.; Das, S.; Devline, M.J.; Dobbs, M.; Dodelson, S; Wollack, E. J.

    2013-01-01

    Fluctuations in the intensity and polarization of the cosmic microwave background (CMB) and the large-scale distribution of matter in the universe each contain clues about the nature of the earliest moments of time. The next generation of CMB and large-scale structure (LSS) experiments are poised to test the leading paradigm for these earliest moments---the theory of cosmic inflation---and to detect the imprints of the inflationary epoch, thereby dramatically increasing our understanding of fundamental physics and the early universe. A future CMB experiment with sufficient angular resolution and frequency coverage that surveys at least 1 of the sky to a depth of 1 uK-arcmin can deliver a constraint on the tensor-to-scalar ratio that will either result in a 5-sigma measurement of the energy scale of inflation or rule out all large-field inflation models, even in the presence of foregrounds and the gravitational lensing B-mode signal. LSS experiments, particularly spectroscopic surveys such as the Dark Energy Spectroscopic Instrument, will complement the CMB effort by improving current constraints on running of the spectral index by up to a factor of four, improving constraints on curvature by a factor of ten, and providing non-Gaussianity constraints that are competitive with the current CMB bounds.

  12. Inflation physics from the cosmic microwave background and large scale structure

    NASA Astrophysics Data System (ADS)

    Abazajian, K. N.; Arnold, K.; Austermann, J.; Benson, B. A.; Bischoff, C.; Bock, J.; Bond, J. R.; Borrill, J.; Buder, I.; Burke, D. L.; Calabrese, E.; Carlstrom, J. E.; Carvalho, C. S.; Chang, C. L.; Chiang, H. C.; Church, S.; Cooray, A.; Crawford, T. M.; Crill, B. P.; Dawson, K. S.; Das, S.; Devlin, M. J.; Dobbs, M.; Dodelson, S.; Doré, O.; Dunkley, J.; Feng, J. L.; Fraisse, A.; Gallicchio, J.; Giddings, S. B.; Green, D.; Halverson, N. W.; Hanany, S.; Hanson, D.; Hildebrandt, S. R.; Hincks, A.; Hlozek, R.; Holder, G.; Holzapfel, W. L.; Honscheid, K.; Horowitz, G.; Hu, W.; Hubmayr, J.; Irwin, K.; Jackson, M.; Jones, W. C.; Kallosh, R.; Kamionkowski, M.; Keating, B.; Keisler, R.; Kinney, W.; Knox, L.; Komatsu, E.; Kovac, J.; Kuo, C.-L.; Kusaka, A.; Lawrence, C.; Lee, A. T.; Leitch, E.; Linde, A.; Linder, E.; Lubin, P.; Maldacena, J.; Martinec, E.; McMahon, J.; Miller, A.; Mukhanov, V.; Newburgh, L.; Niemack, M. D.; Nguyen, H.; Nguyen, H. T.; Page, L.; Pryke, C.; Reichardt, C. L.; Ruhl, J. E.; Sehgal, N.; Seljak, U.; Senatore, L.; Sievers, J.; Silverstein, E.; Slosar, A.; Smith, K. M.; Spergel, D.; Staggs, S. T.; Stark, A.; Stompor, R.; Vieregg, A. G.; Wang, G.; Watson, S.; Wollack, E. J.; Wu, W. L. K.; Yoon, K. W.; Zahn, O.; Zaldarriaga, M.

    2015-03-01

    Fluctuations in the intensity and polarization of the cosmic microwave background (CMB) and the large-scale distribution of matter in the universe each contain clues about the nature of the earliest moments of time. The next generation of CMB and large-scale structure (LSS) experiments are poised to test the leading paradigm for these earliest moments-the theory of cosmic inflation-and to detect the imprints of the inflationary epoch, thereby dramatically increasing our understanding of fundamental physics and the early universe. A future CMB experiment with sufficient angular resolution and frequency coverage that surveys at least 1% of the sky to a depth of 1 uK-arcmin can deliver a constraint on the tensor-to-scalar ratio that will either result in a 5 σ measurement of the energy scale of inflation or rule out all large-field inflation models, even in the presence of foregrounds and the gravitational lensing B-mode signal. LSS experiments, particularly spectroscopic surveys such as the Dark Energy Spectroscopic Instrument, will complement the CMB effort by improving current constraints on running of the spectral index by up to a factor of four, improving constraints on curvature by a factor of ten, and providing non-Gaussianity constraints that are competitive with the current CMB bounds.

  13. Could multiple voids explain the cosmic microwave background Cold Spot anomaly?

    NASA Astrophysics Data System (ADS)

    Naidoo, Krishna; Benoit-Lévy, Aurélien; Lahav, Ofer

    2016-06-01

    Understanding the observed Cold Spot (CS, temperature of ˜ - 150 μK at its centre) on the cosmic microwave background is an outstanding problem. Explanations vary from assuming it is just a ≳3σ primordial Gaussian fluctuation to the imprint of a supervoid via the Integrated Sachs-Wolfe and Rees-Sciama (ISW+RS) effects. Since single spherical supervoids cannot account for the full profile, the ISW+RS of multiple line-of-sight voids is studied here to mimic the structure of the cosmic web. Two structure configurations are considered. The first, through simulations of 20 voids, produces a central mean temperature of ˜ - 50 μK. In this model the central CS temperature lies at ˜2σ but fails to explain the CS hot ring. An alternative multivoid model (using more pronounced compensated voids) produces much smaller temperature profiles, but contains a prominent hot ring. Arrangements containing closely placed voids at low redshift are found to be particularly well suited to produce CS-like profiles. We then measure the significance of the CS if CS-like profiles (which are fitted to the ISW+RS of multivoid scenarios) are removed. The CS tension with the Λ cold dark matter model can be reduced dramatically for an array of temperature profiles smaller than the CS itself.

  14. The Nature of the Unresolved Extragalactic Cosmic Soft X-Ray Background

    NASA Technical Reports Server (NTRS)

    Cappelluti, N.; Ranalli, P.; Roncarelli, M.; Arevalo, P.; Zamorani, G.; Comastri, A.; Gilli, R.; Rovilos, E.; Vignali, C.; Allevato, V.; Finoguenov, A.; Miyaji, T.; Nicastro, F.; Georgantopoulos, I.; Kashlinsky, A.

    2013-01-01

    In this paper we investigate the power spectrum of the unresolved 0.5-2 keV cosmic X-ray background (CXB) with deep Chandra 4-Msec (Ms) observations in the Chandra Deep Field South (CDFS). We measured a signal that, on scales >30 arcsec, is significantly higher than the shot noise and is increasing with angular scale. We interpreted this signal as the joint contribution of clustered undetected sources like active galactic nuclei (AGN), galaxies and the intergalactic medium (IGM). The power of unresolved cosmic source fluctuations accounts for approximately 12 per cent of the 0.5-2 keV extragalactic CXB. Overall, our modelling predicts that approximately 20 per cent of the unresolved CXB flux is produced by low-luminosity AGN, approximately 25 per cent by galaxies and approximately 55 per cent by the IGM. We do not find any direct evidence of the so-called 'warm hot intergalactic medium' (i.e. matter with 10(exp 5) less than T less than 10(exp 7) K and density contrast delta less than 1000), but we estimated that it could produce about 1/7 of the unresolved CXB. We placed an upper limit on the space density of postulated X-ray-emitting early black holes at z greater than 7.5 and compared it with supermassive black hole evolution models.

  15. Probing 'Parent Universe' in Loop Quantum Cosmology with B-mode Polarization in Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Lucky Chang, Wen-Hsuan; Proty Wu, Jiun-Huei

    2016-06-01

    We aim to use the observations of B-mode polarization in the Cosmic Microwave Background (CMB) to probe the ‘parent universe’ under the context of Loop Quantum Cosmology (LQC). In particular, we investigate the possibility for the gravitational waves (GW) such as those from the stellar binary systems in the parent universe to survive the big bounce and thus to be still observable today. Our study is based on the background dynamics with the zeroth-order holonomy correction using the Arnowitt-Deser-Misner (ADM) formalism. We propose a new framework in which transfer functions are invoked to bring the GWs in the parent universe through the big bounce, inflation, and big bang to reach today. This transparent and intuitive formalism allows us to accurately discuss the influence of the GWs from the parent universe on the B-mode polarization in the CMB today under backgrounds of different LQC parameters. These features can soon be tested by the forth-coming CMB observations and we note that the LQC backgrounds with symmetric bouncing scenarios are ruled out by the latest observational results from Planck and BICEP2/Keck experiments.

  16. The high-energy diffuse cosmic gamma-ray background radiation from blazars

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Salamon, M. H.; Malkan, M. A.

    1993-01-01

    We predict the spectrum and flux of the high-energy diffuse cosmic gamma-ray background radiation produced by blazars. Our calculations are based on the Compton Observatory EGRET observations of high-energy gamma-rays from these objects, the Whipple observation of TeV gamma-rays from Mrk 421, and radio population studies of flat-spectrum radio sources. Our statistical analysis gives a result consistent with a linear correlation. We then use the radio luminosity function and redshift evolution to calculate the gamma-ray background. We find that blazars cannot account for the flux level or steep spectrum of the background observed by SAS 2 in the sub-GeV range, but could likely provide the dominant background component in the multi-GeV energy range and above. We predict a differential photon spectral index for this component of about 2 up to about 10 GeV. Above that energy, the spectrum should gradually steepen owing to pair production by interactions of the gamma-rays with intergalactic infrared photons. Using the calculations of this effect by Stecker et al. (1992), we estimate a spectral index of about 3.5 for energies above a TeV.

  17. Anisotropies in the cosmic neutrino background after Wilkinson Microwave Anisotropy Probe five-year data

    SciTech Connect

    De Bernardis, Francesco; Pagano, Luca; Melchiorri, Alessandro; Serra, Paolo; Cooray, Asantha E-mail: luca.pagano@roma1.infn.it E-mail: alessandro.melchiorri@roma1.infn.it

    2008-06-15

    We search for the presence of cosmological neutrino background (CNB) anisotropies in recent Wilkinson Microwave Anisotropy Probe (WMAP) five-year data using their signature imprinted on modifications to the cosmic microwave background (CMB) anisotropy power spectrum. By parameterizing the neutrino background anisotropies with the speed viscosity parameter c{sub vis}, we find that the WMAP five-year data alone provide only a weak indication for CNB anisotropies with c{sub vis}{sup 2}>0.06 at the 95% confidence level. When we combine CMB anisotropy data with measurements of galaxy clustering, the SN-Ia Hubble diagram, and other cosmological information, the detection increases to c{sub vis}{sup 2}>0.16 at the same 95% confidence level. Future data from Planck, combined with a weak lensing survey such as the one expected with DUNE from space, will be able to measure the CNB anisotropy parameter at about 10% accuracy. We discuss the degeneracy between neutrino background anisotropies and other cosmological parameters such as the number of effective neutrinos species and the dark energy equation of state.

  18. The cosmic microwave background radiation temperature at a redshift of 2.34.

    PubMed

    Srianand, R; Petitjean, P; Ledoux, C

    The existence of the cosmic microwave background radiation is a fundamental prediction of hot Big Bang cosmology, and its temperature should increase with increasing redshift. At the present time (redshift z = 0), the temperature has been determined with high precision to be T(CMBR)(0) = 2.726 +/- 0.010 K. In principle, the background temperature can be determined using measurements of the relative populations of atomic fine-structure levels, which are excited by the background radiation. But all previous measurements have achieved only upper limits, thus still formally permitting the radiation temperature to be constant with increasing redshift. Here we report the detection of absorption lines from the first and second fine-structure levels of neutral carbon atoms in an isolated cloud of gas at z = 2.3371. We also detected absorption due to several rotational transitions of molecular hydrogen, and fine-structure lines of singly ionized carbon. These constraints enable us to determine that the background radiation was indeed warmer in the past: we find that T(CMBR)(z = 2.3371) is between 6.0 and 14 K. This is in accord with the temperature of 9.1 K predicted by hot Big Bang cosmology. PMID:11140672

  19. An All Silicon Feedhorn-Coupled Focal Plane for Cosmic Microwave Background Polarimetry

    NASA Technical Reports Server (NTRS)

    Hubmayr, J.; Appel, J. W.; Austermann, J. E.; Beall, J. A.; Becker, D.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Crites, A. T.; Essinger-Hileman, T.; Fox, A.; George, E. M.; Halverson, N. W.; Harrington, N. L.; Henning, J. W.; Hilton, G. C.; Irwin, K. D.; Li, D.; Niemack, M. D.; Nibarger, J. P.; VanLanen, J.; Newburgh, L. B.; Parker, L. P.

    2011-01-01

    Upcoming experiments aim to produce high fidelity polarization maps of the cosmic microwave background. To achieve the required sensitivity, we are developing monolithic, feedhorn-coupled transition edge sensor polarimeter arrays operating at 150 GHz. We describe this focal plane architecture and the current status of this technology, focusing on single-pixel polarimeters being deployed on the Atacama B-mode Search (ABS) and an 84-pixel demonstration feedhorn array backed by four 10-pixel polarimeter arrays. The feedhorn array exhibits symmetric beams, cross-polar response less than -23 dB and excellent uniformity across the array. Monolithic polarimeter arrays, including arrays of silicon feedhorns, will be used in the Atacama Cosmology Telescope Polarimeter (ACTPol) and the South Pole Telescope Polarimeter (SPTpol) and have been proposed for upcoming balloon-borne instruments.

  20. Neutral Hydrogen Structures Trace Dust Polarization Angle: Implications for Cosmic Microwave Background Foregrounds

    NASA Astrophysics Data System (ADS)

    Clark, S. E.; Hill, J. Colin; Peek, J. E. G.; Putman, M. E.; Babler, B. L.

    2015-12-01

    Using high-resolution data from the Galactic Arecibo L-Band Feed Array HI (GALFA-Hi) survey, we show that linear structure in Galactic neutral hydrogen (Hi) correlates with the magnetic field orientation implied by Planck 353 GHz polarized dust emission. The structure of the neutral interstellar medium is more tightly coupled to the magnetic field than previously known. At high Galactic latitudes, where the Planck data are noise dominated, the Hi data provide an independent constraint on the Galactic magnetic field orientation, and hence the local dust polarization angle. We detect strong cross-correlations between template maps constructed from estimates of dust intensity combined with either Hi-derived angles, starlight polarization angles, or Planck 353 GHz angles. The Hi data thus provide a new tool in the search for inflationary gravitational wave B -mode polarization in the cosmic microwave background, which is currently limited by dust foreground contamination.

  1. Small-scale cosmic microwave background anisotropies as probe of the geometry of the universe

    NASA Technical Reports Server (NTRS)

    Kamionkowski, Marc; Spergel, David N.; Sugiyama, Naoshi

    1994-01-01

    We perform detailed calculations of cosmic microwave background (CMB) anisotropies in a cold dark matter (CDM)-dominated open universe with primordial adiabatic density perturbations for a variety of reionization histories. The CMB anisotropies depend primarily on the geometry of the universe, which in a matter-dominated universe is determined by Omega and the optical depth to the surface of last scattering. In particular, the location on the primary Doppler peak depends primarily on Omega and is fairly insensitive to the other unknown parameters, such as Omega(sub b), h, Lambda, and the shape of the power spectrum. Therefore, if the primordial density perturbations are adiabatic, measurements of CMB anisotropies on small scales may be used to determine Omega.

  2. Neutral Hydrogen Structures Trace Dust Polarization Angle: Implications for Cosmic Microwave Background Foregrounds.

    PubMed

    Clark, S E; Hill, J Colin; Peek, J E G; Putman, M E; Babler, B L

    2015-12-11

    Using high-resolution data from the Galactic Arecibo L-Band Feed Array HI (GALFA-Hi) survey, we show that linear structure in Galactic neutral hydrogen (Hi) correlates with the magnetic field orientation implied by Planck 353 GHz polarized dust emission. The structure of the neutral interstellar medium is more tightly coupled to the magnetic field than previously known. At high Galactic latitudes, where the Planck data are noise dominated, the Hi data provide an independent constraint on the Galactic magnetic field orientation, and hence the local dust polarization angle. We detect strong cross-correlations between template maps constructed from estimates of dust intensity combined with either Hi-derived angles, starlight polarization angles, or Planck 353 GHz angles. The Hi data thus provide a new tool in the search for inflationary gravitational wave B-mode polarization in the cosmic microwave background, which is currently limited by dust foreground contamination. PMID:26705622

  3. Searching for concentric low variance circles in the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    DeAbreu, Adam; Contreras, Dagoberto; Scott, Douglas

    2015-12-01

    In a recent paper, Gurzadyan & Penrose claim to have found directions in the sky around which there are multiple concentric sets of annuli with anomalously low variance in the cosmic microwave background (CMB). These features are presented as evidence for a particular theory of the pre-Big Bang Universe. We are able to reproduce the analysis these authors presented for data from the WMAP satellite and we confirm the existence of these apparently special directions in the newer Planck data. However, we also find that these features are present at the same level of abundance in simulated Gaussian CMB skies, i.e., they are entirely consistent with the predictions of the standard cosmological model.

  4. Probing the effective number of neutrino species with the cosmic microwave background

    SciTech Connect

    Ichikawa, Kazuhide; Sekiguchi, Toyokazu; Takahashi, Tomo

    2008-10-15

    We discuss how much we can probe the effective number of neutrino species N{sub {nu}} with the cosmic microwave background alone. Using the data of the WMAP, ACBAR, CBI, and BOOMERANG experiments, we obtain a constraint on the effective number of neutrino species as 0.96

  5. Design Studies for a Far Infrared Absolute Spectrometer for the Cosmic Background Explorer

    NASA Technical Reports Server (NTRS)

    Johnson, N. J. E.

    1980-01-01

    Unrelenting symmetry of design is required to assure the thermal balance of a cryogenically cooled, rapid scan interferometer spectrometer to be mounted in vacuum with the Cosmic Background Explorer liquid helium dewar. The instrument receives inputs from Winston cone optical flux collectors, one open to space and a second coupled to a black body reference source. A differential instrument, the spectrometer produces outputs corresponding to the Fourier transform of the spectral radiance difference between the two inputs. The two outputs are sensed by four detectors, two optimized for shorter wavelength response, and two optimized for longer wavelengths. The optical design, detector and signal channel, system sensitivity, mechanics, thermal control and cryogenics, electronics and power systems, command and control, calibration, system test requirements, and the instrument interface are discussed. Recommendations for continued work are indicated for the superconducting reflective horns, the motor bearing and drive, and design detail.

  6. SMALL ANGULAR SCALE MEASUREMENTS OF THE COSMIC MICROWAVE BACKGROUND TEMPERATURE POWER SPECTRUM FROM QUaD

    SciTech Connect

    Friedman, R. B.; Culverhouse, T.; Ade, P.; Bowden, M.; Gear, W. K.; Gupta, S.; Orlando, A.; Bock, J.; Leitch, E.; Brown, M. L.; Cahill, G.; Murphy, J. A.; Castro, P. G.; Memari, Y.; Church, S.; Hinderks, J.; Ganga, K.; Melhuish, S. J.

    2009-08-01

    We present measurements of the cosmic microwave background (CMB) radiation temperature anisotropy in the multipole range 2000 < l < 3000 from the QUaD telescope's second and third observing seasons. After masking the brightest point sources our results are consistent with the primary {lambda}CDM expectation alone. We estimate the contribution of residual (un-masked) radio point sources using a model calibrated to our own bright source observations, and a full simulation of the source finding and masking procedure. Including this contribution slightly improves the {chi}{sup 2}. We also fit a standard Sunyaev-Zel'dovich (SZ) template to the bandpowers and see no strong evidence of an SZ contribution, which is as expected for {sigma}{sub 8} {approx} 0.8.

  7. Direct detection of the cosmic neutrino background including light sterile neutrinos

    NASA Astrophysics Data System (ADS)

    Li, Y. F.; Xing, Zhi-Zhong; Luo, Shu

    2010-09-01

    Current cosmological data drop an interesting hint about the existence of sub-eV sterile neutrinos, which should be a part of the cosmic neutrino background (CνB). We point out that such light sterile neutrinos may leave a distinct imprint on the electron energy spectrum in the capture of relic electron neutrinos by means of radioactive beta-decaying nuclei. We examine possible signals of sterile neutrinos relative to active neutrinos, characterized by their masses and sensitive to their number densities, in the reaction ν+H3→He3+e- against the corresponding tritium beta decay. We stress that this kind of direct laboratory detection of the CνB and its sterile component might not be hopeless in the long term.

  8. Lensed cosmic microwave background constraints on post-general-relativity parameters

    SciTech Connect

    Serra, Paolo; Cooray, Asantha; Daniel, Scott F.; Caldwell, Robert; Melchiorri, Alessandro

    2009-05-15

    The constraints on departures from general relativity (GR) at cosmological length scales due to cosmic microwave background (CMB) data are discussed. The departure from GR is measured by the ratio, parametrized as 1+{pi}{sub 0}(1+z){sup -S}, between the gravitational potentials conventionally appearing in the geodesic equation and the Poisson equation. Current CMB data indicate {pi}{sub 0}=1.67{sub -1.87}{sup +3.07} at the 2{sigma} confidence level, while S remains unconstrained. The departure from GR affects the lensing conversion of E-mode into B-mode polarization. Hence, the lensing measurements from CMBpol alone should be able to improve the constraint to {pi}{sub 0}<0.52 (2{sigma}) for a fiducial {pi}{sub 0}=0 model independent of S.

  9. IS THE COSMIC MICROWAVE BACKGROUND ASYMMETRY DUE TO THE KINEMATIC DIPOLE?

    SciTech Connect

    Naselsky, P.; Zhao, W.; Kim, J.; Chen, S.

    2012-04-10

    Parity violation found in the cosmic microwave background (CMB) radiation is a crucial clue for the non-standard cosmological model or the possible contamination of various foreground residuals and/or calibration of the CMB data sets. In this paper, we study the directional properties of the CMB parity asymmetry by excluding the m = 0 modes in the definition of parity parameters. We find that the preferred directions of the parity parameters coincide with the CMB kinematic dipole, which implies that the CMB parity asymmetry may be connected with the possible contamination of the residual dipole component. We also find that such tendency is not only localized at l = 2, 3, but in the extended multipole ranges up to l {approx} 22.

  10. Measurement of the large-scale anisotropy of the cosmic background radiation at 3mm

    SciTech Connect

    Epstein, G.L.

    1983-12-01

    A balloon-borne differential radiometer has measured the large-scale anisotropy of the cosmic background radiation (CBR) with high sensitivity. The antenna temperature dipole anistropy at 90 GHz (3 mm wavelength) is 2.82 +- 0.19 mK, corresponding to a thermodynamic anistropy of 3.48 +- mK for a 2.7 K blackbody CBR. The dipole direction, 11.3 +- 0.1 hours right ascension and -5.7/sup 0/ +- 1.8/sup 0/ declination, agrees well with measurements at other frequencies. Calibration error dominates magnitude uncertainty, with statistical errors on dipole terms being under 0.1 mK. No significant quadrupole power is found, placing a 90% confidence-level upper limit of 0.27 mK on the RMS thermodynamic quadrupolar anistropy. 22 figures, 17 tables.

  11. Cold dark matter and degree-scale cosmic microwave background anisotropy statistics after COBE

    NASA Technical Reports Server (NTRS)

    Gorski, Krzysztof M.; Stompor, Radoslaw; Juszkiewicz, Roman

    1993-01-01

    We conduct a Monte Carlo simulation of the cosmic microwave background (CMB) anisotropy in the UCSB South Pole 1991 degree-scale experiment. We examine cold dark matter cosmology with large-scale structure seeded by the Harrison-Zel'dovich hierarchy of Gaussian-distributed primordial inhomogeneities normalized to the COBE-DMR measurement of large-angle CMB anisotropy. We find it statistically implausible (in the sense of low cumulative probability F lower than 5 percent, of not measuring a cosmological delta-T/T signal) that the degree-scale cosmological CMB anisotropy predicted in such models could have escaped a detection at the level of sensitivity achieved in the South Pole 1991 experiment.

  12. Intracluster Comptonization of the Cosmic Microwave Background: Mean Spectral Distortion and Cluster Number Counts

    NASA Astrophysics Data System (ADS)

    Colafrancesco, S.; Mazzotta, P.; Rephaeli, Y.; Vittorio, N.

    1997-04-01

    The mean sky-averaged Comptonization parameter, ȳ, describing the scattering of the cosmic microwave background (CMB) by hot gas in clusters of galaxies, is calculated in an array of flat and open cosmological and dark matter models. The models are globally normalized to fit cluster X-ray data, and intracluster gas is assumed to have evolved in a manner consistent with current observations. We predict values of ȳ lower than the COBE/FIRAS upper limit. The corresponding values of the overall optical thickness to Compton scattering are <~10-4 for relevant parameter values. Of more practical importance are number counts of clusters across which a net flux (with respect to the CMB) higher than some limiting value can be detected. Such number counts are specifically predicted for the COBRAS/SAMBA and BOOMERANG missions.

  13. Systematic Effects in Polarizing Fourier Transform Spectrometers for Cosmic Microwave Background Observations

    NASA Astrophysics Data System (ADS)

    Nagler, Peter C.; Fixsen, Dale J.; Kogut, Alan; Tucker, Gregory S.

    2015-11-01

    The detection of the primordial B-mode polarization signal of the cosmic microwave background (CMB) would provide evidence for inflation. Yet as has become increasingly clear, the detection of a such a faint signal requires an instrument with both wide frequency coverage to reject foregrounds and excellent control over instrumental systematic effects. Using a polarizing Fourier transform spectrometer (FTS) for CMB observations meets both of these requirements. In this work, we present an analysis of instrumental systematic effects in polarizing FTSs, using the Primordial Inflation Explorer (PIXIE) as a worked example. We analytically solve for the most important systematic effects inherent to the FTS—emissive optical components, misaligned optical components, sampling and phase errors, and spin synchronous effects—and demonstrate that residual systematic error terms after corrections will all be at the sub-nK level, well below the predicted 100 nK B-mode signal.

  14. Resolving the Cosmic X-ray Background with NuSTAR and Chandra

    NASA Astrophysics Data System (ADS)

    Hickox, Ryan C.

    2016-04-01

    Although its origin was long mysterious, the cosmic X-ray background (CXB) is now known to be primarily the sum of emission from large number of active galactic nuclei (AGN). With the advent of NuSTAR, the first focusing high-energy X-ray observatory, we can now directly identify the sources that contribute to the bulk of the CXB at energies > 10 keV where the CXB spectrum peaks. I will present an analysis using data from the NuSTAR extragalactic survey program in which we using stacking techniques to determine the fraction of the CXB that is produced by X-ray sources identified at softer energies by deep Chandra observations. These results provide important constraints on AGN synthesis models fo the CXB and point toward a further "missing" population of obscured AGN. This work is supported in part by NASA award NNX15AP24G.

  15. A new line-of-sight approach to the non-linear Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Fidler, Christian; Koyama, Kazuya; Pettinari, Guido W.

    2015-04-01

    We develop the transport operator formalism, a new line-of-sight integration framework to calculate the anisotropies of the Cosmic Microwave Background (CMB) at the linear and non-linear level. This formalism utilises a transformation operator that removes all inhomogeneous propagation effects acting on the photon distribution function, thus achieving a split between perturbative collisional effects at recombination and non-perturbative line-of-sight effects at later times. The former can be computed in the framework of standard cosmological perturbation theory with a second-order Boltzmann code such as SONG, while the latter can be treated within a separate perturbative scheme allowing the use of non-linear Newtonian potentials. We thus provide a consistent framework to compute all physical effects contained in the Boltzmann equation and to combine the standard remapping approach with Boltzmann codes at any order in perturbation theory, without assuming that all sources are localised at recombination.

  16. Fast cosmic microwave background power spectrum estimation of temperature and polarization with Gabor transforms

    NASA Astrophysics Data System (ADS)

    Hansen, Frode K.; Górski, Krzysztof M.

    2003-08-01

    We extend the analysis of Gabor transforms on a cosmic microwave background temperature map to polarization. We study the temperature and polarization power spectra on the cut sky, the so-called pseudo-power spectra. The transformation kernels relating the full-sky polarization power spectra and the polarization pseudo-power spectra are found to be similar to the kernel for the temperature power spectrum. This fact is used to construct a fast power spectrum estimation algorithm using the pseudo-power spectrum of temperature and polarization as data vectors in a maximum-likelihood approach. Using the pseudo-power spectra as input to the likelihood analysis solves the problem of having to invert huge matrices, which makes the standard likelihood approach infeasible.

  17. Joint cosmic microwave background and weak lensing analysis: constraints on cosmological parameters.

    PubMed

    Contaldi, Carlo R; Hoekstra, Henk; Lewis, Antony

    2003-06-01

    We use cosmic microwave background (CMB) observations together with the red-sequence cluster survey weak lensing results to derive constraints on a range of cosmological parameters. This particular choice of observations is motivated by their robust physical interpretation and complementarity. Our combined analysis, including a weak nucleosynthesis constraint, yields accurate determinations of a number of parameters including the amplitude of fluctuations sigma(8)=0.89+/-0.05 and matter density Omega(m)=0.30+/-0.03. We also find a value for the Hubble parameter of H(0)=70+/-3 km s(-1) Mpc(-1), in good agreement with the Hubble Space Telescope key-project result. We conclude that the combination of CMB and weak lensing data provides some of the most powerful constraints available in cosmology today. PMID:12857304

  18. The y-sky: diffuse spectral distortions of the cosmic microwave background

    SciTech Connect

    Pitrou, Cyril; Bernardeau, Francis; Uzan, Jean-Philippe E-mail: francis.bernardeau@cea.fr

    2010-07-01

    The non-linear evolution of the energy density of the radiation induces spectral distortions of the cosmic microwave background both at recombination and during the reionization era. This distortion has the same spectral signature as the one produced by the re-scattering of photons by non-relativistic hot electrons, the thermal Sunyaev-Zeldovich effect, whose amplitude is quantified by a Compton y parameter. A diffuse y-sky is then expected to emerge from mode couplings in the non-linear evolution of the cosmological perturbations and to superimpose to the point source contributions of galaxy clusters. The equations describing the evolution of the y field and a hierarchy governing its angular multipoles are derived from the second order Boltzmann equation. These equations are then integrated numerically to obtain the first predicted power spectrum of the diffuse y-sky. It is found to be a remarkable tracer of the reionization history of the Universe.

  19. Measurement of the intensity of the cosmic background radiation at 3. 0 cm

    SciTech Connect

    Friedman, S.D.

    1984-01-01

    The intensity of the cosmic background radiation (CBR) has been measured at a wavelength of 3.0 cm as part of a program to measure th Rayleigh-Jeans spectrum of the CBR at five wavelengths between 0.33 cm and 12 cm. The instrument used is a dual-antenna Dicke-switched radiometer with a double-sideband noise temperature of 490 K and a sensitivity of 46 mK/Hz/sup 1/2/. The entire radiometer is mounted on bearings. The atmospheric emission was measured by rotating the radiometer, and thus directing one antenna to zenith angles of +- 30/sup 0/ and +- 40/sup 0/. 61 references, 24 figures, 18 tables.

  20. Simulated cosmic microwave background maps at 0.5 deg resolution: Basic results

    NASA Technical Reports Server (NTRS)

    Hinshaw, G.; Bennett, C. L.; Kogut, A.

    1995-01-01

    We have simulated full-sky maps of the cosmic microwave background (CMB) anisotropy expected from cold dark matter (CDM) models at 0.5 deg and 1.0 deg angular resolution. Statistical properties of the maps are presented as a function of sky coverage, angular resolution, and instrument noise, and the implications of these results for observability of the Doppler peak are discussed. The rms fluctuations in a map are not a particularly robust probe of the existence of a Doppler peak; however, a full correlation analysis can provide reasonable sensitivity. We find that sensitivity to the Doppler peak depends primarily on the fraction of sky covered, and only secondarily on the angular resolution and noise level. Color plates of the simulated maps are presented to illustrate the anisotropies.

  1. Bayesian Analysis of the Power Spectrum of the Cosmic Microwave Background

    NASA Technical Reports Server (NTRS)

    Jewell, Jeffrey B.; Eriksen, H. K.; O'Dwyer, I. J.; Wandelt, B. D.

    2005-01-01

    There is a wealth of cosmological information encoded in the spatial power spectrum of temperature anisotropies of the cosmic microwave background. The sky, when viewed in the microwave, is very uniform, with a nearly perfect blackbody spectrum at 2.7 degrees. Very small amplitude brightness fluctuations (to one part in a million!!) trace small density perturbations in the early universe (roughly 300,000 years after the Big Bang), which later grow through gravitational instability to the large-scale structure seen in redshift surveys... In this talk, I will discuss a Bayesian formulation of this problem; discuss a Gibbs sampling approach to numerically sampling from the Bayesian posterior, and the application of this approach to the first-year data from the Wilkinson Microwave Anisotropy Probe. I will also comment on recent algorithmic developments for this approach to be tractable for the even more massive data set to be returned from the Planck satellite.

  2. Simulation of Cosmic Microwave Background Polarization Fields for AMiBA Experiment

    NASA Astrophysics Data System (ADS)

    Park, Chan-Gyung; Park, Changbom

    2002-06-01

    We have made a topological study of cosmic microwave background (CMB) polarization maps by simulating the AMiBA experiment results. A ΛCDM CMB sky is adopted to make mock interferometric observations designed for the AMiBA experiment. CMB polarization fields are reconstructed from the AMiBA mock visibility data using the maximum entropy method. We have also considered effects of Galactic foregrounds on the CMB polarization fields. The genus statistic is calculated from the simulated Q and U polarization maps, where Q and U are Stokes parameters. Our study shows that the Galactic foreground emission, even at low Galactic latitude, is expected to have small effects on the CMB polarization field. Increasing survey area and integration time is essential to detect non-Gaussian signals of cosmological origin through genus measurement.

  3. Studying Heavy Ion Collisions Using Methods From Cosmic Microwave Background (CMB) Analysis

    NASA Astrophysics Data System (ADS)

    Gaardhøje, J. J.; Tabassam, H.

    2014-04-01

    We present and discuss a framework for studying the morphology of high-multiplicity events from relativistic heavy ion collisions using methods commonly employed in the analysis of the photons from the Cosmic Microwave Background (CMB). The analysis is based on the decomposition of the distribution of the number density of (charged) particles expressed in polar and azimuthal coordinates into a sum of spherical harmonic functions. We present an application of the method exploting relevant symmetries to the study of azimuthal correlations arizing from collective flow among charged particles produced in relativistic heavy ion collisions. We discuss perspectives for event-by- event analyses, which with increasing collision energy will eventually open entirely new dimensions in the study of ultrarelaticistic heavy ion reactions.

  4. Constraints on nonconformal couplings from the properties of the cosmic microwave background radiation.

    PubMed

    van de Bruck, Carsten; Morrice, Jack; Vu, Susan

    2013-10-18

    Certain modified gravity theories predict the existence of an additional, nonconformally coupled scalar field. A disformal coupling of the field to the cosmic microwave background (CMB) is shown to affect the evolution of the energy density in the radiation fluid and produces a modification of the distribution function of the CMB, which vanishes if photons and baryons couple in the same way to the scalar. We find the constraints on the couplings to matter and photons coming from the measurement of the CMB temperature evolution and from current upper limits on the μ distortion of the CMB spectrum. We also point out that the measured equation of state of photons differs from w(γ)=1/3 in the presence of disformal couplings. PMID:24182251

  5. Anisotropy of the Cosmic Microwave Background Radiation on Large and Medium Angular Scales

    NASA Technical Reports Server (NTRS)

    Houghton, Anthony; Timbie, Peter

    1998-01-01

    This grant has supported work at Brown University on measurements of the 2.7 K Cosmic Microwave Background Radiation (CMB). The goal has been to characterize the spatial variations in the temperature of the CMB in order to understand the formation of large-scale structure in the universe. We have concurrently pursued two measurements using millimeter-wave telescopes carried aloft by scientific balloons. Both systems operate over a range of wavelengths, chosen to allow spectral removal of foreground sources such as the atmosphere, Galaxy, etc. The angular resolution of approx. 25 arcminutes is near the angular scale at which the most structure is predicted by current models to be visible in the CMB angular power spectrum. The main goal is to determine the angular scale of this structure; in turn we can infer the density parameter, Omega, for the universe as well as other cosmological parameters, such as the Hubble constant.

  6. ISOTROPY IN THE TWO-POINT ANGULAR CORRELATION FUNCTION OF THE COSMIC MICROWAVE BACKGROUND

    SciTech Connect

    Zhang, Sophie

    2012-04-01

    We study the directional dependence of the angular two-point correlation function in maps of the cosmic microwave background (CMB). We propose two new statistics: one which measures the correlation of each point in the sky with a ring of points separated an angle {theta} away, and a second one that measures the missing angular correlation above 60 deg as a function of direction. Using these statistics, we find that most of the low power in cut-sky maps measured by the Wilkinson Microwave Anisotropy Probe experiment comes from unusually low contributions from the directions of the lobes of the quadrupole and the octupole. These findings may aid a future explanation of why the CMB exhibits low power at large angular scales.

  7. Isotropic blackbody cosmic microwave background radiation as evidence for a homogeneous universe.

    PubMed

    Clifton, Timothy; Clarkson, Chris; Bull, Philip

    2012-08-01

    The question of whether the Universe is spatially homogeneous and isotropic on the largest scales is of fundamental importance to cosmology but has not yet been answered decisively. Surprisingly, neither an isotropic primary cosmic microwave background (CMB) nor combined observations of luminosity distances and galaxy number counts are sufficient to establish such a result. The inclusion of the Sunyaev-Zel'dovich effect in CMB observations, however, dramatically improves this situation. We show that even a solitary observer who sees an isotropic blackbody CMB can conclude that the Universe is homogeneous and isotropic in their causal past when the Sunyaev-Zel'dovich effect is present. Critically, however, the CMB must either be viewed for an extended period of time, or CMB photons that have scattered more than once must be detected. This result provides a theoretical underpinning for testing the cosmological principle with observations of the CMB alone. PMID:23006164

  8. Achromatic half-wave plate for submillimeter instruments in cosmic microwave background astronomy: experimental characterization.

    PubMed

    Pisano, Giampaolo; Savini, Giorgio; Ade, Peter A R; Haynes, Vic; Gear, Walter K

    2006-09-20

    An achromatic half-wave plate (HWP) to be used in millimeter cosmic microwave background (CMB) polarization experiments has been designed, manufactured, and tested. The design is based on the 5-plates Pancharatnam recipe and it works in the frequency range 85-185 GHz. A model has been used to predict the transmission, reflection, absorption, and phase shift as a function of frequency. The HWP has been tested by using coherent radiation from a back-wave oscillator to investigate its modulation efficiency and with incoherent radiation from a polarizing Fourier transform spectrometer (FTS) to explore its frequency behavior. The FTS measurements have been fitted with an optical performance model which is in excellent agreement with the data. A detailed analysis of the data also allows a precise determination of the HWP fast and slow axes in the frequency band of operation. A list of the HWP performance characteristics is reported including estimates of its cross polarization. PMID:16946775

  9. Cosmic-ray imaging of spent fuel casks

    NASA Astrophysics Data System (ADS)

    Guardincerri, Elena; Durham, J. Matthew; Morris, Christopher; Poulson, Daniel; Plaud-Ramos, Kenie; Fabritius, Joseph; Bacon, Jeffrey; Winston, Philip; Chichester, David

    2015-10-01

    Muon radiography was used to image the inside of a partially loaded Westinghouse MC-10 dry cask containing spent nuclear fuel at Idaho National Laboratory. We present here the results of a 100 hours long measurement taken in May 2015 with two muon trackers placed outside the cask. The data clearly show the location of the missing fuel bundles and demonstrate the feasibility of using cosmic rays to monitor fuel casks against illicit diversion of their content.

  10. LIGO Gravitational Wave Detection, Primordial Black Holes, and the Near-IR Cosmic Infrared Background Anisotropies

    NASA Astrophysics Data System (ADS)

    Kashlinsky, A.

    2016-06-01

    LIGO's discovery of a gravitational wave from two merging black holes (BHs) of similar masses rekindled suggestions that primordial BHs (PBHs) make up the dark matter (DM). If so, PBHs would add a Poissonian isocurvature density fluctuation component to the inflation-produced adiabatic density fluctuations. For LIGO's BH parameters, this extra component would dominate the small-scale power responsible for collapse of early DM halos at z ≳ 10, where first luminous sources formed. We quantify the resultant increase in high-z abundances of collapsed halos that are suitable for producing the first generation of stars and luminous sources. The significantly increased abundance of the early halos would naturally explain the observed source-subtracted near-IR cosmic infrared background (CIB) fluctuations, which cannot be accounted for by known galaxy populations. For LIGO's BH parameters, this increase is such that the observed CIB fluctuation levels at 2–5 μm can be produced if only a tiny fraction of baryons in the collapsed DM halos forms luminous sources. Gas accretion onto these PBHs in collapsed halos, where first stars should also form, would straightforwardly account for the observed high coherence between the CIB and unresolved cosmic X-ray background in soft X-rays. We discuss modifications possibly required in the processes of first star formation if LIGO-type BHs indeed make up the bulk or all of DM. The arguments are valid only if the PBHs make up all, or at least most, of DM, but at the same time the mechanism appears inevitable if DM is made of PBHs.

  11. A Map of the Cosmic Microwave Background from the BEAST Experiment

    NASA Astrophysics Data System (ADS)

    Meinhold, Peter R.; Bersanelli, Marco; Childers, Jeffrey; Figueiredo, Newton; Gaier, Todd C.; Halevi, Doron; Huey, Gregory G.; Kangas, Miikka; Lawrence, Charles R.; Levy, Alan; Lubin, Philip M.; Malaspina, Marco; Mandolesi, Nazzareno; Marvil, Joshua; Mejía, Jorge; Natoli, Paolo; O'Dwyer, Ian; O'Neill, Hugh; Parendo, Shane; Pina, Agenor; Seiffert, Michael D.; Stebor, Nathan C.; Tello, Camilo; Villa, Fabrizio; Villela, Thyrso; Wade, Lawrence A.; Wandelt, Benjamin D.; Williams, Brian; Wuensche, Carlos Alexandre

    2005-05-01

    We present the first sky maps from the BEAST (Background Emission Anisotropy Scanning Telescope) experiment. BEAST consists of a 2.2 m off-axis Gregorian telescope fed by a cryogenic millimeter wavelength focal plane currently consisting of six Q band (40 GHz) and two Ka band (30 GHz) scalar feed horns feeding cryogenic HEMT amplifiers. Data were collected from two balloon-borne flights in 2000, followed by a lengthy ground observing campaign from the 3.8 km altitude University of California White Mountain Research Station. This paper reports the initial results from the ground-based observations. The instrument produced an annular map covering the sky over 33deg<δ<42deg. The maps cover an area of 2470 deg2 with an effective resolution of 23' FWHM at 40 GHz and 30' at 30 GHz. The map rms (smoothed to 30' and excluding Galactic foregrounds) is 57+/-5 μK (Rayleigh-Jeans) at 40 GHz. Comparison with the instrument noise and correcting for 5% atmospheric attenuation gives a cosmic signal rms contribution of 29+/-3 μK (R-J) or 30+/-3 μK relative to a Planck blackbody of 2.7 K. An estimate of the actual cosmic microwave background (CMB) sky signal requires taking into account the l space filter function of our experiment and analysis techniques, carried out in a companion paper. In addition to the robust detection of CMB anisotropies, we find a strong correlation between small portions of our maps and features in recent Hα maps. In this work we describe the data set and analysis techniques leading to the maps, including data selection, filtering, pointing reconstruction, mapmaking algorithms, and systematic effects.

  12. A measurement of the low frequency spectrum of the cosmic microwave background radiation

    SciTech Connect

    Levin, S.M.

    1987-04-01

    As part of a larger effort to measure the spectrum of the Cosmic Background Radiation (CBR) at low frequencies, the intensity of the CBR has been measured at a frequency of 1.410 GHz. The measurement was made by comparing the power received from the sky with the power received from a specially designed cooled calibration target with known properties. Sources of radiation other than the CBR were then identified and subtracted to calculate the antenna temperature of the CBR at 1.410 GHz. The instrument used to measure the CBR was a total-power microwave radiometer with a 25 MHz bandwidth centered at 1.410 GHz. The radiometer had a noise temperature of 80 K, and sufficient data were taken that radiometer noise did not contribute significantly to the total measurement error. The sources of error were predominantly systematic in nature, and the largest error was due to uncertainty in the reflection characteristics of the cold-load calibrator. Identification and subtraction of signals from the Galaxy (0.7 K) and the Earth's atmosphere (0.8 K) were also significant parts of the data reduction and error analysis. The brightness temperature of the Cosmic Background Radiation at 1.410 GHz is 222. +- 0.55 Kelvin. The spectrum of the CBR, as determined by this measurement and other published results, is consistent with a blackbody spectrum of temperature 2.741 +- 0.016. Constraints on the amount by which the CBR spectrum deviates from Planck spectrum are used to place limits on energy releases early in the history of the universe. 55 refs., 25 figs., 8 tabs.

  13. Natural inflation: consistency with cosmic microwave background observations of Planck and BICEP2

    NASA Astrophysics Data System (ADS)

    Freese, Katherine; Kinney, William H.

    2015-03-01

    Natural inflation is a good fit to all cosmic microwave background (CMB) data and may be the correct description of an early inflationary expansion of the Universe. The large angular scale CMB polarization experiment BICEP2 has announced a major discovery, which can be explained as the gravitational wave signature of inflation, at a level that matches predictions by natural inflation models. The natural inflation (NI) potential is theoretically exceptionally well motivated in that it is naturally flat due to shift symmetries, and in the simplest version takes the form V(phi) = Λ4 [1 ± cos(Nphi/f)]. A tensor-to-scalar ratio r > 0.1 as seen by BICEP2 requires the height of any inflationary potential to be comparable to the scale of grand unification and the width to be comparable to the Planck scale. The Cosine Natural Inflation model agrees with all cosmic microwave background measurements as long as f >= mPl (where mPl = 1.22 × 1019 GeV) and Λ ~ mGUT ~ 1016 GeV. This paper also discusses other variants of the natural inflation scenario: we show that axion monodromy with potential Vpropto phi2/3 is inconsistent with the BICEP2 limits at the 95% confidence level, and low-scale inflation is strongly ruled out. Linear potentials V propto phi are inconsistent with the BICEP2 limit at the 95% confidence level, but are marginally consistent with a joint Planck/BICEP2 limit at 95%. We discuss the pseudo-Nambu Goldstone model proposed by Kinney and Mahanthappa as a concrete realization of low-scale inflation. While the low-scale limit of the model is inconsistent with the data, the large-field limit of the model is marginally consistent with BICEP2. All of the models considered predict negligible running of the scalar spectral index, and would be ruled out by a detection of running.

  14. Cosmic Microwave Background Constraints on the Duration and Timing of Reionization from the South Pole Telescope

    NASA Astrophysics Data System (ADS)

    Zahn, O.; Reichardt, C. L.; Shaw, L.; Lidz, A.; Aird, K. A.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Dobbs, M. A.; Doré, O.; Dudley, J.; George, E. M.; Halverson, N. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hou, Z.; Hrubes, J. D.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Lueker, M.; Luong-Van, D.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Millea, M.; Mohr, J. J.; Montroy, T. E.; Natoli, T.; Padin, S.; Plagge, T.; Pryke, C.; Ruhl, J. E.; Schaffer, K. K.; Shirokoff, E.; Spieler, H. G.; Staniszewski, Z.; Stark, A. A.; Story, K.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Williamson, R.

    2012-09-01

    The epoch of reionization is a milestone of cosmological structure formation, marking the birth of the first objects massive enough to yield large numbers of ionizing photons. However, the mechanism and timescale of reionization remain largely unknown. Measurements of the cosmic microwave background (CMB) Doppler effect from ionizing bubbles embedded in large-scale velocity streams—known as the patchy kinetic Sunyaev-Zel'dovich (kSZ) effect—can be used to constrain the duration of reionization. When combined with large-scale CMB polarization measurements, the evolution of the ionized fraction, {\\bar{x}}_e, can be inferred. Using new multi-frequency data from the South Pole Telescope (SPT), we show that the ionized fraction evolved relatively rapidly. For our basic foreground model, we find the kSZ power sourced by reionization at l = 3000 to be D patchy 3000 <= 2.1 μK2 at 95% confidence. Using reionization simulations, we translate this to a limit on the duration of reionization of \\Delta z \\equiv z_{{\\bar{x}}_e=0.20}-z_{{\\bar{x}}_e=0.99} \\le 4.4 (95% confidence). We find that this constraint depends on assumptions about the angular correlation between the thermal SZ power and the cosmic infrared background (CIB). Introducing the degree of correlation as a free parameter, we find that the limit on kSZ power weakens to D patchy 3000 <= 4.9 μK2, implying Δz <= 7.9 (95% confidence). We combine the SPT constraint on the duration of reionization with the Wilkinson Microwave Anisotropy Probe measurement of the integrated optical depth to probe the cosmic ionization history. We find that reionization ended with 95% confidence at z > 7.2 under the assumption of no tSZ-CIB correlation, and z > 5.8 when correlations are allowed. Improved constraints from the full SPT data set in conjunction with upcoming Herschel and Planck data should detect extended reionization at >95% confidence provided Δz >= 2. These CMB observations complement other observational probes

  15. Background character research for synthetical performance of thermal imaging systems

    NASA Astrophysics Data System (ADS)

    Chen, Song-lin; Wang, Ji-hui; Wang, Xiao-wei; Jin, Wei-qi

    2014-05-01

    Background is assumed to be uniform usually for evaluating the performance of thermal imaging systems, however the impact of background cannot be ignored for target acquisition in reality, background character is important research content for thermal imaging technology. A background noise parameter 𝜎 was proposed in MRTD model and used to describe background character. Background experiments were designed, and some typical backgrounds (namely lawn background, concrete pavement background, trees background and snow background) character were analyzed by 𝜎. MRTD including 𝜎 was introduced into MRTD-Channel Width (CW) model, the impact of above typical backgrounds for target information quantity were analyzed by MRTD-CW model with background character. Target information quantity for different backgrounds was calculated by MRTD-CW, and compared with that of TTP model. A target acquisition performance model based on MRTD-CW with background character will be research in the future.

  16. Correlations Between the Cosmic X-Ray and Microwave Backgrounds: Constraints on a Cosmological Constant

    NASA Technical Reports Server (NTRS)

    Boughn, S. P.; Crittenden, R. G.; Turok, N. G.

    1998-01-01

    In universes with significant curvature or cosmological constant, cosmic microwave background (CMB) anisotropies are created very recently via the Rees-Sciama or integrated Sachs-Wolfe effects. This causes the CMB anisotropies to become partially correlated with the local matter density (z less than 4). We examine the prospects of using the hard (2- 10 keV) X-ray background as a probe of the local density and the measured correlation between the HEAO1 A2 X-ray survey and the 4-year COBE-DMR map to obtain a constraint on the cosmological constant. The 95% confidence level upper limit on the cosmological constant is OMega(sub Lambda) less than or equal to 0.5, assuming that the observed fluctuations in the X-ray map result entirely from large scale structure. (This would also imply that the X-rays trace matter with a bias factor of b(sub x) approx. = 5.6 Omega(sub m, sup 0.53)). This bound is weakened considerably if a large portion of the X-ray fluctuations arise from Poisson noise from unresolved sources. For example, if one assumes that the X-ray bias is b(sub x) = 2, then the 95% confidence level upper limit is weaker, Omega(sub Lambda) less than or equal to 0.7. More stringent limits should be attainable with data from the next generation of CMB and X-ray background maps.

  17. A SEARCH FOR COSMIC MICROWAVE BACKGROUND ANISOTROPIES ON ARCMINUTE SCALES WITH BOLOCAM

    SciTech Connect

    Sayers, J.; Golwala, S. R.; Rossinot, P.; Edgington, S. F.; Lange, A. E.; Ade, P. A. R.; Haig, D.; Mauskopf, P. D.; Aguirre, J. E.; Glenn, J.; Laurent, G. T.; Bock, J. J.; Goldin, A.; Nguyen, H. T.

    2009-01-10

    We have surveyed two science fields totaling 1 deg.{sup 2} with Bolocam at 2.1 mm to search for secondary Cosmic Microwave Background (CMB) anisotropies caused by the Sunyaev-Zel'dovich effect (SZE). The fields are in the Lynx and Subaru/XMM SDS1 fields. Our survey is sensitive to angular scales with an effective angular multipole of l{sub eff} = 5700 with FWHM{sub l} = 2800 and has an angular resolution of 60 arcsec FWHM. Our data provide no evidence for anisotropy. We are able to constrain the level of total astronomical anisotropy, modeled as a flat-band power in C{sub l}, with most frequent 68%, 90%, and 95% CL upper limits of 590, 760, and 830 {mu}K {sup 2} {sub CMB}. We statistically subtract the known contribution from primary CMB anisotropy, including cosmic variance, to obtain constraints on the SZE anisotropy contribution. Now including flux calibration uncertainty, our most frequent 68%, 90%, and 95% CL upper limits on a flat-band power in C{sub l} are 690, 960, and 1000 {mu}K {sup 2} {sub CMB}. When we instead employ the analytical spectrum suggested by Komatsu and Seljack in 2002, and account for the non-Gaussianity of the SZE anisotropy signal, we obtain upper limits on the average amplitude of their spectrum weighted by our transfer function of 790, 1060, and 1080 {mu}K {sup 2} {sub CMB}. We obtain a 90% CL upper limit on {sigma}{sub 8}, which normalizes the power spectrum of density fluctuations, of 1.57. These are the first constraints on anisotropy and {sigma}{sub 8} from survey data at these angular scales at frequencies near 150 GHz.

  18. Semi-blind Eigen Analyses of Recombination Histories Using Cosmic Microwave Background Data

    NASA Astrophysics Data System (ADS)

    Farhang, M.; Bond, J. R.; Chluba, J.

    2012-06-01

    Cosmological parameter measurements from cosmic microwave background (CMB) experiments, such as Planck, ACTPol, SPTPol, and other high-resolution follow-ons, fundamentally rely on the accuracy of the assumed recombination model or one with well-prescribed uncertainties. Deviations from the standard recombination history might suggest new particle physics or modified atomic physics. Here we treat possible perturbative fluctuations in the free electron fraction, X e(z), by a semi-blind expansion in densely packed modes in redshift. From these we construct parameter eigenmodes, which we rank order so that the lowest modes provide the most power to probe X e(z) with CMB measurements. Since the eigenmodes are effectively weighed by the fiducial X e history, they are localized around the differential visibility peak, allowing for an excellent probe of hydrogen recombination but a weaker probe of the higher redshift helium recombination and the lower redshift highly neutral freezeout tail. We use an information-based criterion to truncate the mode hierarchy and show that with even a few modes the method goes a long way from the fiducial recombination model computed with RECFAST, X e, i(z), toward the precise underlying history given by the new and improved recombination calculations of COSMOREC or HYREC, X e, f(z), in the hydrogen recombination regime, though not well in the helium regime. Without such a correction, the derived cosmic parameters are biased. We discuss an iterative approach for updating the eigenmodes to further hone in on X e, f(z) if large deviations are indeed found. We also introduce control parameters that downweight the attention on the visibility peak structure, e.g., focusing the eigenmode probes more strongly on the X e(z) freezeout tail, as would be appropriate when looking for the X e signature of annihilating or decaying elementary particles.

  19. SEMI-BLIND EIGEN ANALYSES OF RECOMBINATION HISTORIES USING COSMIC MICROWAVE BACKGROUND DATA

    SciTech Connect

    Farhang, M.; Bond, J. R.; Chluba, J.

    2012-06-20

    Cosmological parameter measurements from cosmic microwave background (CMB) experiments, such as Planck, ACTPol, SPTPol, and other high-resolution follow-ons, fundamentally rely on the accuracy of the assumed recombination model or one with well-prescribed uncertainties. Deviations from the standard recombination history might suggest new particle physics or modified atomic physics. Here we treat possible perturbative fluctuations in the free electron fraction, X{sub e}(z), by a semi-blind expansion in densely packed modes in redshift. From these we construct parameter eigenmodes, which we rank order so that the lowest modes provide the most power to probe X{sub e}(z) with CMB measurements. Since the eigenmodes are effectively weighed by the fiducial X{sub e} history, they are localized around the differential visibility peak, allowing for an excellent probe of hydrogen recombination but a weaker probe of the higher redshift helium recombination and the lower redshift highly neutral freezeout tail. We use an information-based criterion to truncate the mode hierarchy and show that with even a few modes the method goes a long way from the fiducial recombination model computed with RECFAST, X{sub e,i}(z), toward the precise underlying history given by the new and improved recombination calculations of COSMOREC or HYREC, X{sub e,f}(z), in the hydrogen recombination regime, though not well in the helium regime. Without such a correction, the derived cosmic parameters are biased. We discuss an iterative approach for updating the eigenmodes to further hone in on X{sub e,f}(z) if large deviations are indeed found. We also introduce control parameters that downweight the attention on the visibility peak structure, e.g., focusing the eigenmode probes more strongly on the X{sub e}(z) freezeout tail, as would be appropriate when looking for the X{sub e} signature of annihilating or decaying elementary particles.

  20. Delensing cosmic microwave background B modes with the Square Kilometre Array Radio Continuum Survey

    NASA Astrophysics Data System (ADS)

    Namikawa, Toshiya; Yamauchi, Daisuke; Sherwin, Blake; Nagata, Ryo

    2016-02-01

    We explore the potential use of the Radio Continuum (RC) survey conducted by the Square Kilometre Array (SKA) to remove (delens) the lensing-induced B-mode polarization and thus enhance future cosmic microwave background (CMB) searches for inflationary gravitational waves. Measurements of large-scale B-modes of the CMB are considered to be the best method for probing gravitational waves from the cosmic inflation. Future CMB experiments will, however, suffer from contamination by nonprimordial B modes, one source of which is the lensing B modes. Delensing, therefore, will be required for further improvement of the detection sensitivity for gravitational waves. Analyzing the use of the two-dimensional map of galaxy distribution provided by the SKA RC survey as a lensing mass tracer, we find that joint delensing using near-future CMB experiments and the SKA phase 1 will improve the constraints on the tensor-to-scalar ratio by more than a factor of ˜2 compared to those without the delensing analysis. Compared to the use of CMB data alone, the inclusion of the SKA phase 1 data will increase the significance of the constraints on the tensor-to-scalar ratio by a factor 1.2-1.6. For LiteBIRD combined with a ground-based experiment such as Simons Array and Advanced ACT, the constraint on the tensor-to-scalar ratio when adding SKA phase 2 data is improved by a factor of 2.3-2.7, whereas delensing with CMB data alone improves the constraints by only a factor 1.3-1.7. We conclude that the use of SKA data is a promising method for delensing upcoming CMB experiments such as LiteBIRD.

  1. Cross-terms and weak frequency-dependent signals in the cosmic microwave background sky

    NASA Astrophysics Data System (ADS)

    Hernández-Monteagudo, C.; Sunyaev, R. A.

    2005-05-01

    In this paper, we study the amplification of weak frequency-dependent signals in the cosmic microwave background (CMB) sky due to their cross-correlation to intrinsic anisotropies. In particular, we centre our attention on mechanisms generating a weak signal, of peculiar spectral behaviour, such as resonant scattering in ionic, atomic or molecular lines, the thermal Sunyaev-Zel'dovich (tSZ) effect or extragalactic foreground emissions, whose typical amplitude (denoted by ɛ) is significantly smaller than the intrinsic CMB fluctuations. We find that all these effects involve either the autocorrelation of anisotropies generated during recombination (zrec) or the cross-correlation of those anisotropies with fluctuations arising at redshift zi. The former case accounts for the slight blurring of original anisotropies generated in the last scattering surface, and shows up in the small angular scale (high multipole) range. The latter term describes, instead, the generation of new anisotropies, and is non-zero only if fluctuations generated at redshifts zrec, zi, are correlated. The degree of this correlation can be computed under the assumption that density fluctuations were generated as standard inflationary models dictate and that they evolved in time according to linear theory. When the weak signal is frequency dependent (i.e. the spectral dependence of the secondary anisotropies is distinct from that of the CMB), we show that, by subtracting power spectra at different frequencies, it is possible to avoid the limit associated with cosmic variance and unveil weaker terms linear in ɛ. We find that the correlation term shows a different spectral dependence than the squared (~ɛ2) term usually considered, making its extraction particularly straightforward for the tSZ effect. Furthermore, we find that in most cases the correlation terms are particularly relevant at low multipoles due to the integrated Sachs-Wolfe effect and must be taken into account when characterizing

  2. Detecting signatures of cosmological recombination and reionization in the cosmic radio background

    NASA Astrophysics Data System (ADS)

    Subrahmanyan, Ravi; Shankar Narayana Rao, Udaya; Sathyanarayana Rao, Mayuri; Singh, Saurabh

    2015-08-01

    Evolution of the baryons during the Epochs of cosmological Recombination and Reionization has left traces in the cosmic radio background in the form of spectral distortions (Sunyaev & Chluba 2008 Astron. Nachrichten, 330, 657; Pritchard & Loeb 2012 Rep Prog Phys 75(8):086901). The spectral signature depends on the evolution in the ionization state in hydrogen and helium and on the spin temperature of hydrogen. These probe the physics of energy release beyond the last scattering surface at redshifts exceeding 1090 and the nature of the first sources and gas evolution down to redshift about 6. The spectral distortions are sensitive to the nature of the first stars, ultra-dwarf galaxies, accreting compact objects, and the evolving ambient radiation field: X-rays and UV from the first sources. Detection of the all-sky or global spectral distortions in the radio background is hence a probe of cosmological recombination and reionization.We present new spectral radiometers that we have purpose designed for precision measurements of spectral distortions at radio wavelengths. New antenna elements include frequency independent and electrically small fat-dipole (Raghunathan et al. 2013 IEEE TAP, 61, 3411) and monopole designs. Receiver configurations have been devised that are self-calibratable (Patra et al. 2013 Expt Astron, 36, 319) so that switching of signal paths and of calibration noise sources provide real time calibration for systematics and receiver noise. Observing strategies (Patra et al. arXiv:1412.7762) and analysis methods (Satyanarayana Rao et al. arXiv:1501.07191) have been evolved that are capable of discriminating between the cosmological signals and the substantially brighter foregrounds. We have also demonstrated the value of system designs that exploit advantages of interferometer detection (Mahesh et al. arXiv:1406.2585) of global spectral distortions.Finally we discuss how the Square Kilometer Array stations may be outfitted with precision spectral

  3. Simulating the Scintillating Cosmic Ray Eliminating ENsemble (SuNSCREEN) for reducing cosmic background in experiments relevant for the p-process

    NASA Astrophysics Data System (ADS)

    Klopfer, Emily; Spyrou, Artemis; Simon, Anna; Quinn, Stephen; Dombos, Alexander; Deyoung, Paul; Brett, Jaclyn

    2013-10-01

    Naturally occurring, proton rich isotopes that cannot be produced in the s- or r- neutron capture processes are called p-nuclei. Their nucleosynthesis proceeds by the p-process; a process that is still not well understood. This process may be studied by measuring (p, γ) and (α, γ) reactions using the Summing NaI(TI) detector (SuN) created at NSCL. The SuN detector uses a summing technique where all the gamma rays emitted from a single compound nucleus are summed into one peak that can then be analyzed. One problem with this method is the background created by cosmic rays at high-energy regions of the gamma spectrum. To counteract this drawback a veto detector, SuNSCREEN (Scintillating Cosmic Ray Eliminating Ensemble), is being developed to reduce this cosmic ray background. The present work was centered on producing a simulation of SuNSCREEN and cosmic rays utilizing GEANT4 software and the comparison of these simulations to experimental data.

  4. The Primordial Inflation Explorer (PIXIE): A Nulling Polarimeter for Cosmic Microwave Background Observations

    NASA Technical Reports Server (NTRS)

    Kogut, Alan J.; Fixsen, D. J.; Chuss, D. T.; Dotson, J.; Dwek, E.; Halpern, M.; Hinshaw, G. F.; Meyer, S. M.; Moseley, S. H.; Seiffert, M. D.; Spergel, D. N.; Wollack, E. J.

    2011-01-01

    The Primordial Inflation Explorer (PIXIE) is a concept for an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. The instrument consists of a polarizing Michelson interferometer configured as a nulling polarimeter to measure the difference spectrum between orthogonal linear polarizations from two co-aligned beams. Either input can view the sky or a temperature-controlled absolute reference blackbody calibrator. Rhe proposed instrument can map the absolute intensity and linear polarization (Stokes I, Q, and U parameters) over the full sky in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). Multi-moded optics provide background-limited sensitivity using only 4 detectors, while the highly symmetric design and multiple signal modulations provide robust rejection of potential systematic errors. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r < 10..3 at 5 standard deviations. The rich PIXIE data set can also constrain physical processes ranging from Big Bang cosmology to the nature of the first stars to physical conditions within the interstellar medium of the Galaxy.

  5. Neutrino physics from the cosmic microwave background and large scale structure

    SciTech Connect

    Abazajian, K. N.; Arnold, K.; Austermann, J. E.; Benson, B. A.; Bischoff, C.; Brock, J.; Bond, J. R.; Borrill, J.; Calabrese, E.; Carlstrom, J. E.; Chang, C. L.

    2015-03-15

    This is a report on the status and prospects of the quantification of neutrino properties through the cosmological neutrino background for the Cosmic Frontier of the Division of Particles and Fields Community Summer Study long-term planning exercise. Experiments planned and underway are prepared to study the cosmological neutrino background in detail via its influence on distance-redshift relations and the growth of structure. The program for the next decade described in this document, including upcoming spectroscopic galaxy surveys eBOSS and DESI and a new Stage-IV CMB polarization experiment CMB-S4, will achieve σ (σmν)(σmν) = 16 meV and σ (Neff)(Neff) = 0.020. Such a mass measurement will produce a high significance detection of non-zero σmνσmν, whose lower bound derived from atmospheric and solar neutrino oscillation data is about 58 meV. If neutrinos have a minimal normal mass hierarchy, this measurement will definitively rule out the inverted neutrino mass hierarchy, shedding light on one of the most puzzling aspects of the Standard Model of particle physics — the origin of mass. This precise a measurement of NeffNeff will allow for high sensitivity to any light and dark degrees of freedom produced in the big bang and a precision test of the standard cosmological model prediction that View the MathML sourceNeff=3.046.

  6. Neutrino Physics from the Cosmic Microwave Background and Large Scale Structure

    DOE PAGESBeta

    Abazajian, K. N.; Arnold, K.; Austermann, J.; Benson, B. A.; Bischoff, C.; Bock, J.; Bond, J. R.; Borrill, J.; Calabrese, E.; Carlstrom, J. E.; et al

    2014-03-15

    This is a report on the status and prospects of the quantification of neutrino properties through the cosmological neutrino background for the Cosmic Frontier of the Division of Particles and Fields Community Summer Study long-term planning exercise. Experiments planned and underway are prepared to study the cosmological neutrino background in detail via its influence on distance-redshift relations and the growth of structure. The program for the next decade described in this document, including upcoming spectroscopic galaxy surveys eBOSS and DESI and a new Stage-IV CMB polarization experiment CMB-S4, will achieve σ (σmv) = 16 meV and σ (Neff)(Neff) = 0.020.more » Such a mass measurement will produce a high significance detection of non-zero σmνσmν, whose lower bound derived from atmospheric and solar neutrino oscillation data is about 58 meV. If neutrinos have a minimal normal mass hierarchy, this measurement will definitively rule out the inverted neutrino mass hierarchy, shedding light on one of the most puzzling aspects of the Standard Model of particle physics — the origin of mass. This precise a measurement of Neff will allow for high sensitivity to any light and dark degrees of freedom produced in the big bang and a precision test of the standard cosmological model prediction that Neff = 3.046.« less

  7. Neutrino Physics from the Cosmic Microwave Background and Large Scale Structure

    SciTech Connect

    Abazajian, K. N.; Arnold, K.; Austermann, J.; Benson, B. A.; Bischoff, C.; Bock, J.; Bond, J. R.; Borrill, J.; Calabrese, E.; Carlstrom, J. E.; Carvalho, C. S.; Chang, C. L.; Chiang, H. C.; Church, S.; Cooray, A.; Crawford, T. M.; Dawson, K. S.; Das, S.; Devlin, M. J.; Dobbs, M.; Dodelson, S.; Dore, O.; Dunkley, J.; Errard, J.; Fraisse, A.; Gallicchio, J.; Halverson, N. W.; Hanany, S.; Hildebrandt, S. R.; Hincks, A.; Hlozek, R.; Holder, G.; Holzapfel, W. L.; Honscheid, K.; Hu, W.; Hubmayr, J.; Irwin, K.; Jones, W. C.; Kamionkowski, M.; Keating, B.; Keisler, R.; Knox, L.; Komatsu, E.; Kovac, J.; Kuo, C. -L.; Lawrence, C.; Lee, A. T.; Leitch, E.; Linder, E.; Lubin, P.; McMahon, J.; Miller, A.; Newburgh, L.; Niemack, M. D.; Nguyen, H.; Nguyen, H. T.; Page, L.; Pryke, C.; Reichardt, C. L.; Ruhl, J. E.; Sehgal, N.; Seljak, U.; Sievers, J.; Silverstein, E.; Slosar, A.; Smith, K. M.; Spergel, D.; Staggs, S. T.; Stark, A.; Stompor, R.; Wang, G.; Watson, S.; Wollack, E. J.; W. Wu; Yoon, K. W.; Zahn, O.

    2014-03-15

    This is a report on the status and prospects of the quantification of neutrino properties through the cosmological neutrino background for the Cosmic Frontier of the Division of Particles and Fields Community Summer Study long-term planning exercise. Experiments planned and underway are prepared to study the cosmological neutrino background in detail via its influence on distance-redshift relations and the growth of structure. The program for the next decade described in this document, including upcoming spectroscopic galaxy surveys eBOSS and DESI and a new Stage-IV CMB polarization experiment CMB-S4, will achieve σ (σmv) = 16 meV and σ (Neff)(Neff) = 0.020. Such a mass measurement will produce a high significance detection of non-zero σmνσmν, whose lower bound derived from atmospheric and solar neutrino oscillation data is about 58 meV. If neutrinos have a minimal normal mass hierarchy, this measurement will definitively rule out the inverted neutrino mass hierarchy, shedding light on one of the most puzzling aspects of the Standard Model of particle physics — the origin of mass. This precise a measurement of Neff will allow for high sensitivity to any light and dark degrees of freedom produced in the big bang and a precision test of the standard cosmological model prediction that Neff = 3.046.

  8. An Analysis of Recent Measurements of the Temperature of the Cosmic Microwave Background Radiation

    DOE R&D Accomplishments Database

    Smoot, G.; Levin, S. M.; Witebsky, C.; De Amici, G.; Rephaeli, Y.

    1987-07-01

    This paper presents an analysis of the results of recent temperature measurements of the cosmic microwave background radiation (CMBR). The observations for wavelengths longer than 0.1 cum are well fit by a blackbody spectrum at 2.74{+ or -}0.0w K; however, including the new data of Matsumoto et al. (1987) the result is no longer consistent with a Planckian spectrum. The data are described by a Thomson-distortion parameter u=0.021{+ or -}0.002 and temperature 2.823{+ or -}0.010 K at the 68% confidence level. Fitting the low-frequency data to a Bose-Einstein spectral distortion yields a 95% confidence level upper limit of 1.4 x 10{sup -2} on the chemical potential mu{sub 0}. These limits on spectral distortions place restrictions on a number of potentially interesting sources of energy release to the CMBR, including the hot intergalactic medium proposed as the source of the X-ray background.

  9. Cryogenic Optical Assembly (COA) cooldown analysis for the Cosmic Background Explorer (COBE)

    NASA Technical Reports Server (NTRS)

    Coladonato, Robert J.; Irish, Sandra M.; Mosier, Carol L.

    1990-01-01

    The Cosmic Background Explorer (COBE) spacecraft, developed by Goddard Space Flight Center (GSFC), was successfully launched on November 18, 1989 aboard a Delta expendable launch vehicle. Two of the three instruments for this mission were mounted inside a liquid helium (LHe) dewar which operates at a temperature of 2 K. These two instruments are the Diffuse Infrared Background Experiment (DIRBE) and the Far Infrared Absolute Spectrophotometer (FIRAS). They are mounted to a common Instrument Interface Structure (IIS) and the entire assembly is called the Cryogenic Optical Assembly (COA). As part of the structural verification requirement, it was necessary to show that the entire COA exhibited adequate strength and would be capable of withstanding the launch environment. This requirement presented an unique challenge for COBE because the COA is built and assembled at room temperature (300 K), cooled to 2 K, and then subjected to launch loads. However, strength testing of the entire COA at 2 K could not be done because of facility limitations. Therefore, it was decided to perform the strength verification of the COA by analysis.

  10. Large-Angular-Scale Anisotropy in the Cosmic BackgroundRadiation

    SciTech Connect

    Gorenstein, M.V.; Smoot, G.F.

    1980-05-01

    We report the results of an extended series of airborne measurements of large-angular-scale anisotropy in the 3 K cosmic background radiation. Observations were carried out with a dual-antenna microwave radiometer operating at 33 GHz (0.89 cm wavelength) flown on board a U-2 aircraft to 20 km altitude. In eleven flights, between December 1976 and May 1978, the radiometer measured differential intensity between pairs of directions distributed over most of the northern hemisphere with an rms sensitivity of 47 mK Hz{sup -1/2}. The measurements show clear evidence of anisotropy that is readily interpreted as due to the solar motion relative to the sources of the radiation. The anisotropy is well fit by a first order spherical harmonic of amplitude 360 {+-} 50km sec{sup -1} toward the direction 11.2 {+-} 0.5 hours of right ascension and 19 {+-} 8 degrees declination. A simultaneous fit to a combined hypothesis of dipole and quadrupole angular distributions places a 1 mK limit on the amplitude of most components of quadrupole anisotropy with 90% confidence. Additional analysis places a 0.5 mK limit on uncorrelated fluctuations (sky-roughness) in the 3 K background on an angular scale of the antenna beam width, about 7 degrees.

  11. Neutrino physics from the cosmic microwave background and large scale structure

    NASA Astrophysics Data System (ADS)

    Abazajian, K. N.; Arnold, K.; Austermann, J.; Benson, B. A.; Bischoff, C.; Bock, J.; Bond, J. R.; Borrill, J.; Calabrese, E.; Carlstrom, J. E.; Carvalho, C. S.; Chang, C. L.; Chiang, H. C.; Church, S.; Cooray, A.; Crawford, T. M.; Dawson, K. S.; Das, S.; Devlin, M. J.; Dobbs, M.; Dodelson, S.; Doré, O.; Dunkley, J.; Errard, J.; Fraisse, A.; Gallicchio, J.; Halverson, N. W.; Hanany, S.; Hildebrandt, S. R.; Hincks, A.; Hlozek, R.; Holder, G.; Holzapfel, W. L.; Honscheid, K.; Hu, W.; Hubmayr, J.; Irwin, K.; Jones, W. C.; Kamionkowski, M.; Keating, B.; Keisler, R.; Knox, L.; Komatsu, E.; Kovac, J.; Kuo, C.-L.; Lawrence, C.; Lee, A. T.; Leitch, E.; Linder, E.; Lubin, P.; McMahon, J.; Miller, A.; Newburgh, L.; Niemack, M. D.; Nguyen, H.; Nguyen, H. T.; Page, L.; Pryke, C.; Reichardt, C. L.; Ruhl, J. E.; Sehgal, N.; Seljak, U.; Sievers, J.; Silverstein, E.; Slosar, A.; Smith, K. M.; Spergel, D.; Staggs, S. T.; Stark, A.; Stompor, R.; Vieregg, A. G.; Wang, G.; Watson, S.; Wollack, E. J.; Wu, W. L. K.; Yoon, K. W.; Zahn, O.

    2015-03-01

    This is a report on the status and prospects of the quantification of neutrino properties through the cosmological neutrino background for the Cosmic Frontier of the Division of Particles and Fields Community Summer Study long-term planning exercise. Experiments planned and underway are prepared to study the cosmological neutrino background in detail via its influence on distance-redshift relations and the growth of structure. The program for the next decade described in this document, including upcoming spectroscopic galaxy surveys eBOSS and DESI and a new Stage-IV CMB polarization experiment CMB-S4, will achieve σ (σmν) = 16 meV and σ (Neff) = 0.020. Such a mass measurement will produce a high significance detection of non-zero σmν , whose lower bound derived from atmospheric and solar neutrino oscillation data is about 58 meV. If neutrinos have a minimal normal mass hierarchy, this measurement will definitively rule out the inverted neutrino mass hierarchy, shedding light on one of the most puzzling aspects of the Standard Model of particle physics - the origin of mass. This precise a measurement of Neff will allow for high sensitivity to any light and dark degrees of freedom produced in the big bang and a precision test of the standard cosmological model prediction that Neff = 3.046 .

  12. Resonant signatures of heavy scalar fields in the cosmic microwave background

    SciTech Connect

    Saito, Ryo; Takamizu, Yu-ichi; Nakashima, Masahiro; Yokoyama, Jun'ichi E-mail: nakashima@resceu.s.u-tokyo.ac.jp E-mail: yokoyama@resceu.s.u-tokyo.ac.jp

    2012-11-01

    We investigate the possibility that a heavy scalar field, whose mass exceeds the Hubble scale during inflation, could leave non-negligible signatures in the Cosmic Microwave Background (CMB) temperature anisotropy power spectrum through the parametric resonance between its background oscillations and the inflaton fluctuations. By assuming the heavy scalar field couples with the inflaton derivatively, we show that the resonance can be efficient without spoiling the slow-roll inflation. The primordial power spectrum modulated by the resonance has a sharp peak at a specific scale and could be an origin of the anomalies observed in the angular power spectrum of the CMB. In some values of parameters, the modulated spectrum can fit the observed data better than the simple power-law power spectrum, though the resultant improvement of the fit is not large enough and hence other observations such as non-Gaussianity are necessary to confirm that the CMB anomalies are originated from the resonant effect of the heavy scalar field. The resonant signatures can provide an opportunity to observe heavy degrees of freedom during inflation and improve our understanding of physics behind inflation.

  13. Probing the Cosmic X-Ray and MeV Gamma-Ray Background Radiation through the Anisotropy

    SciTech Connect

    Inoue, Yoshiyuki; Murase, Kohta; Madejski, Grzegorz M.; Uchiyama, Yasunobu

    2013-09-24

    While the cosmic soft X-ray background is very likely to originate from individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV gamma-ray background is not fully understood. It is expected that Seyferts including Compton thick population may explain the cosmic hard X-ray background. At MeV energy range, Seyferts having non-thermal electrons in coronae above accretion disks or MeV blazars may explain the background radiation. We propose that future measurements of the angular power spectra of anisotropy of the cosmic X-ray and MeV gamma-ray backgrounds will be key to deciphering these backgrounds and the evolution of active galactic nuclei (AGNs). As AGNs trace the cosmic large-scale structure, spatial clustering of AGNs exists. We show that e-ROSITA will clearly detect the correlation signal of unresolved Seyferts at 0.5-2 keV and 2-10 keV bands and will be able to measure the bias parameter of AGNs at both bands. Once the future hard X-ray all sky satellites achieve the sensitivity better than 10-12 erg/cm2/s-1 at 10-30 keV or 30-50 keV - although this is beyond the sensitivities of current hard X-ray all sky monitors - angular power spectra will allow us to independently investigate the fraction of Compton-thick AGNs in all Seyferts. We also find that the expected angular power spectra of Seyferts and blazars in the MeV range are different by about an order of magnitude, where the Poisson term, so-called shot noise, is dominant. Current and future MeV instruments will clearly disentangle the origin of the MeV gamma-ray background through the angular power spectrum.

  14. See-through integral imaging display with background occlusion capability.

    PubMed

    Yamaguchi, Yuta; Takaki, Yasuhiro

    2016-01-20

    Background occlusion capability is provided to a flat-panel-type integral imaging display that has a transparent screen and can superimpose three-dimensional (3D) images on real scenes. A symmetric integral imaging system that comprises two integral imaging systems connected by an additional lens array, is proposed. Elementary images are displayed on a flat-panel display on one integral imaging system to generate 3D images, and the occlusion mask patterns are displayed on a flat-panel display on the other integral imaging system to selectively block rays from background scenes. The proposed system was constructed and experimentally verified. PMID:26835946

  15. Planck 2013 results. XXX. Cosmic infrared background measurements and implications for star formation

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bethermin, M.; Bielewicz, P.; Blagrave, K.; Bobin, J.; Bock, J. J.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bridges, M.; Bucher, M.; Burigana, C.; Butler, R. C.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chen, X.; Chiang, H. C.; Chiang, L.-Y.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Ghosh, T.; Giard, M.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Hanson, D.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Kalberla, P.; Keihänen, E.; Kerp, J.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lacasa, F.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Langer, M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Leonardi, R.; León-Tavares, J.; Lesgourgues, J.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M. D.; Serra, P.; Shellard, E. P. S.; Spencer, L. D.; Starck, J.-L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Türler, M.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Welikala, N.; White, M.; White, S. D. M.; Winkel, B.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-11-01

    We present new measurements of cosmic infrared background (CIB) anisotropies using Planck. Combining HFI data with IRAS, the angular auto- and cross-frequency power spectrum is measured from 143 to 3000 GHz, and the auto-bispectrum from 217 to 545 GHz. The total areas used to compute the CIB power spectrum and bispectrum are about 2240 and 4400 deg2, respectively. After careful removal of the contaminants (cosmic microwave background anisotropies, Galactic dust, and Sunyaev-Zeldovich emission), and a complete study of systematics, the CIB power spectrum is measured with unprecedented signal to noise ratio from angular multipoles ℓ ~ 150 to 2500. The bispectrum due to the clustering of dusty, star-forming galaxies is measured from ℓ ~ 130 to 1100, with a total signal to noise ratio of around 6, 19, and 29 at 217, 353, and 545 GHz, respectively. Two approaches are developed for modelling CIB power spectrum anisotropies. The first approach takes advantage of the unique measurements by Planck at large angular scales, and models only the linear part of the power spectrum, with a mean bias of dark matter haloes hosting dusty galaxies at a given redshift weighted by their contribution to the emissivities. The second approach is based on a model that associates star-forming galaxies with dark matter haloes and their subhaloes, using a parametrized relation between the dust-processed infrared luminosity and (sub-)halo mass. The two approaches simultaneously fit all auto- and cross-power spectra very well. We find that the star formation history is well constrained up to redshifts around 2, and agrees with recent estimates of the obscured star-formation density using Spitzer and Herschel. However, at higher redshift, the accuracy of the star formation history measurement is strongly degraded by the uncertainty in the spectral energy distribution of CIB galaxies. We also find that the mean halo mass which is most efficient at hosting star formation is log (Meff/M⊙) = 12

  16. Soft X-ray excess in the Coma cluster from a Cosmic Axion Background

    NASA Astrophysics Data System (ADS)

    Angus, Stephen; Conlon, Joseph P.; Marsh, M. C. David; Powell, Andrew J.; Witkowski, Lukas T.

    2014-09-01

    We show that the soft X-ray excess in the Coma cluster can be explained by a cosmic background of relativistic axion-like particles (ALPs) converting into photons in the cluster magnetic field. We provide a detailed self-contained review of the cluster soft X-ray excess, the proposed astrophysical explanations and the problems they face, and explain how a 0.1- 1 keV axion background naturally arises at reheating in many string theory models of the early universe. We study the morphology of the soft excess by numerically propagating axions through stochastic, multi-scale magnetic field models that are consistent with observations of Faraday rotation measures from Coma. By comparing to ROSAT observations of the 0.2- 0.4 keV soft excess, we find that the overall excess luminosity is easily reproduced for gaγγ ~ 2 × 10-13 Ge -1. The resulting morphology is highly sensitive to the magnetic field power spectrum. For Gaussian magnetic field models, the observed soft excess morphology prefers magnetic field spectra with most power in coherence lengths on Script O(3 kpc) scales over those with most power on Script O(12 kpc) scales. Within this scenario, we bound the mean energy of the axion background to 50 eVlesssim langle Ea rangle lesssim 250 eV, the axion mass to ma lesssim 10-12 eV, and derive a lower bound on the axion-photon coupling gaγγ gtrsim √(0.5/Δ Neff) 1.4 × 10-13 Ge -1.

  17. Soft X-ray excess in the Coma cluster from a Cosmic Axion Background

    SciTech Connect

    Angus, Stephen; Conlon, Joseph P.; Marsh, M.C. David; Powell, Andrew J.; Witkowski, Lukas T. E-mail: j.conlon1@physics.ox.ac.uk E-mail: andrew.powell2@physics.ox.ac.uk

    2014-09-01

    We show that the soft X-ray excess in the Coma cluster can be explained by a cosmic background of relativistic axion-like particles (ALPs) converting into photons in the cluster magnetic field. We provide a detailed self-contained review of the cluster soft X-ray excess, the proposed astrophysical explanations and the problems they face, and explain how a 0.1- 1 keV axion background naturally arises at reheating in many string theory models of the early universe. We study the morphology of the soft excess by numerically propagating axions through stochastic, multi-scale magnetic field models that are consistent with observations of Faraday rotation measures from Coma. By comparing to ROSAT observations of the 0.2- 0.4 keV soft excess, we find that the overall excess luminosity is easily reproduced for g{sub aγγ} ∼ 2 × 10{sup -13} Ge {sup -1}. The resulting morphology is highly sensitive to the magnetic field power spectrum. For Gaussian magnetic field models, the observed soft excess morphology prefers magnetic field spectra with most power in coherence lengths on O(3 kpc) scales over those with most power on O(12 kpc) scales. Within this scenario, we bound the mean energy of the axion background to 50 eV∼< ( E{sub a} ) ∼< 250 eV, the axion mass to m{sub a} ∼< 10{sup -12} eV, and derive a lower bound on the axion-photon coupling g{sub aγγ} ∼> √(0.5/Δ N{sub eff}) 1.4 × 10{sup -13} Ge {sup -1}.

  18. Monte Carlo Simulations of Background Spectra in Integral Imager Detectors

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.; Dietz, K. L.; Ramsey, B. D.; Weisskopf, M. C.

    1998-01-01

    Predictions of the expected gamma-ray backgrounds in the ISGRI (CdTe) and PiCsIT (Csl) detectors on INTEGRAL due to cosmic-ray interactions and the diffuse gamma-ray background have been made using a coupled set of Monte Carlo radiation transport codes (HETC, FLUKA, EGS4, and MORSE) and a detailed, 3-D mass model of the spacecraft and detector assemblies. The simulations include both the prompt background component from induced hadronic and electromagnetic cascades and the delayed component due to emissions from induced radioactivity. Background spectra have been obtained with and without the use of active (BGO) shielding and charged particle rejection to evaluate the effectiveness of anticoincidence counting on background rejection.

  19. The Spectrumof the Cosmic Background Radiation: Early and RecentMeasurements from the White Mountain Research Station

    SciTech Connect

    Smoot, G.F.

    1985-09-01

    The White Mountain Research Station has provided a support facility at a high, dry, radio-quiet site for measurements that have established the blackbody character of the cosmic microwave background radiation. This finding has confirmed the interpretation of the radiation as a relic of the primeval fireball and helped to establish the hot Big Bang theory as the standard cosmological model.

  20. High-energy cosmic antiparticle excess vs. isotropic gamma-ray background problem in decaying dark matter Universe

    NASA Astrophysics Data System (ADS)

    Alekseev, V. V.; Belotsky, K. M.; Bogomolov, Yu V.; Budaev, R. I.; Dunaeva, O. A.; Kirillov, A. A.; Kuznetsov, A. V.; Laletin, M. N.; Lukyanov, A. D.; Malakhov, V. V.; Mayorov, A. G.; Mayorova, M. A.; Mosichkin, A. F.; Okrugin, A. A.; Rodenko, S. A.; Shitova, A. M.

    2016-02-01

    We are going to show that any conventional decaying dark matter model, providing an explanation of cosmic antiparticle excess observed by PAMELA and AMS-02, inevitably faces the contradiction with isotropic diffuse gamma-ray background, measured by FERMI/LAT.

  1. A measurement by BOOMERANG of multiple peaks in the angular power spectrum of the cosmic microwave background

    NASA Technical Reports Server (NTRS)

    Netterfield, C. B.; Ade, P. A. R.; Bock, J. J.; Bond, J. R.; Borrill, J.; Boscaleri, A.; Coble, K.; Contaldi, C. R.; Crill, B. P.; Bernardis, P. de; Farese, P.; Ganga, K.; Giacometti, M.; Hivon, E.; Hristov, V. V.; Iacoangeli, A.; Jaffe, A. H.; Jones, W. C.; Lange, A. E.; Martinis, L.; Masi, S.; Mason, P.; Mauskopf, P.; Melchiorri, A.; Montroy, T.

    2001-01-01

    This paper presents a measurement of the angular power spectrum of the Cosmic Microwave Background from l = 75 to l = 1025 (10' to 5 degrees) from a combined analysis of four 150 GHz channels in the BOOMERANG experiment. The spectrum contains multiple peaks and minima, as predicted by standard adiabatic-inflationary models in which the primordial plasma undergoes acoustic oscillations.

  2. The optimisation, design and verification of feed horn structures for future Cosmic Microwave Background missions

    NASA Astrophysics Data System (ADS)

    McCarthy, Darragh; Trappe, Neil; Murphy, J. Anthony; O'Sullivan, Créidhe; Gradziel, Marcin; Doherty, Stephen; Huggard, Peter G.; Polegro, Arturo; van der Vorst, Maarten

    2016-05-01

    In order to investigate the origins of the Universe, it is necessary to carry out full sky surveys of the temperature and polarisation of the Cosmic Microwave Background (CMB) radiation, the remnant of the Big Bang. Missions such as COBE and Planck have previously mapped the CMB temperature, however in order to further constrain evolutionary and inflationary models, it is necessary to measure the polarisation of the CMB with greater accuracy and sensitivity than before. Missions undertaking such observations require large arrays of feed horn antennas to feed the detector arrays. Corrugated horns provide the best performance, however owing to the large number required (circa 5000 in the case of the proposed COrE+ mission), such horns are prohibitive in terms of thermal, mechanical and cost limitations. In this paper we consider the optimisation of an alternative smooth-walled piecewise conical profiled horn, using the mode-matching technique alongside a genetic algorithm. The technique is optimised to return a suitable design using efficient modelling software and standard desktop computing power. A design is presented showing a directional beam pattern and low levels of return loss, cross-polar power and sidelobes, as required by future CMB missions. This design is manufactured and the measured results compared with simulation, showing excellent agreement and meeting the required performance criteria. The optimisation process described here is robust and can be applied to many other applications where specific performance characteristics are required, with the user simply defining the beam requirements.

  3. Constraints on open universe models from quadruple anisotropy of the cosmic microwave background

    SciTech Connect

    Gouda, Naoteru; Sugiyama, Naoshi; Sasaki, Misao Kyoto University, Uji )

    1991-05-01

    The quadrupole anisotropy of the cosmic microwave background expected in a variety of open universe models is evaluated by taking full account of contributions from both the generalized Sachs-Wolfe effect and intrinsic photon fluctuations at decoupling. Comparing the results with the observed upper limit of the quadrupole anisotropy, constraints on open universe models are derived. It is concluded that, even if the most conservative attitude is adopted, both hot and cold dark matter models with h = 0.5, Omega(0) not greater than 0.2 and all pure baryonic models with Omega(0) not greater than 0.2 are excluded if the initial density spectrum has the power-law index n not greater than 1, while both hot and cold dark matter models with h = 1.0, Omega(0) not greater than 0.2, and n not greater than 1 are marginally consistent with the observed upper limit of the quadrupole if one allows possible ambiguities in the normalization of the perturbation amplitudes. 29 refs.

  4. Contamination cannot explain the lack of large-scale power in the cosmic microwave background radiation

    SciTech Connect

    Bunn, Emory F.; Bourdon, Austin

    2008-12-15

    Several anomalies appear to be present in the large-angle cosmic microwave background (CMB) anisotropy maps of the Wilkinson Microwave Anisotropy Probe. One of these is a lack of large-scale power. Because the data otherwise match standard models extremely well, it is natural to consider perturbations of the standard model as possible explanations. We show that, as long as the source of the perturbation is statistically independent of the source of the primary CMB anisotropy, no such model can explain this large-scale power deficit. On the contrary, any such perturbation always reduces the probability of obtaining any given low value of large-scale power. We rigorously prove this result when the lack of large-scale power is quantified with a quadratic statistic, such as the quadrupole moment. When a statistic based on the integrated square of the correlation function is used instead, we present strong numerical evidence in support of the result. The result applies to models in which the geometry of spacetime is perturbed (e.g., an ellipsoidal universe) as well as explanations involving local contaminants, undiagnosed foregrounds, or systematic errors. Because the large-scale power deficit is arguably the most significant of the observed anomalies, explanations that worsen this discrepancy should be regarded with great skepticism, even if they help in explaining other anomalies such as multipole alignments.

  5. Measurement of Arcminute Scale Cosmic Microwave Background Anisotropy with the BIMA Array

    NASA Technical Reports Server (NTRS)

    Dawson, K. S.; Holzapfel, W. L.; Carlstrom, J. E.; Joy, M.; LaRoque, S. J.; Miller, A.; Nagai, D.; Six, N. Frank (Technical Monitor)

    2002-01-01

    We report the results of our continued study of arcminute scale anisotropy in the Cosmic Microwave Background (CMB) with the Berkeley-Illinois-Maryland Association (BIMA) array. The survey consists of ten independent fields selected for low infrared dust emission and lack of bright radio point sources. With observations from the VLA (Very Large Array) at 4.8 GHz, we have identified point sources which could act as contaminants in estimates of the CMB power spectrum and removed them in the analysis. Modeling the observed power spectrum with a single. flat band power with average multipole of l(sub eff) = 6864, we find Delta T = 14.2((sup +4.8)(sub -6.0)) micro K at 68% confidence. The signal in the visibility data exceeds the expected contribution from instrumental noise with 96.5% confidence. We have also divided the data into two bins corresponding to different spatial resolutions in the power spectrum. We find Delta T(sub 1) = 16.6((sup +5.3)(sub -5.9)) micro K at 68% confidence for CMB flat band power described by an average multipole of l(sub eff) = 5237 and Delta T(sub 2) is less than 26.5 micro K at 95% confidence for l(sub eff) = 8748.

  6. Power spectrum constraints from spectral distortions in the cosmic microwave background

    NASA Technical Reports Server (NTRS)

    Hu, Wayne; Scott, Douglas; Silk, Joseph

    1994-01-01

    Using recent experimental limits on chemical potential distortions from Cosmic Background Explorer (COBE) Far Infrared Astronomy Satellite (FIRAS), and the large lever-arm spanning the damping of sub-Jeans scale fluctuations to the COBE DMR fluctuations, we set a constraint on the slope of the primordial power spectrum n. It is possible to analytically calculate the contribution over the full range of scales and redshifts, correctly taking into account fluctuation growth and damping as well as thermalization processes. Assuming conservatively that mu is less than 1.76 x 10(exp -4), we find that the 95% upper limit on n is only weakly dependent on other cosmological parameters, e.g., n is less than 1.60 (h=0.5) and n is less than 1.63 (h=1.0) for Omega(sub 0) = 1, with marginally weaker constraints for Omega(sub 0) is less than 1 in a flat model with a cosmological constant.

  7. Measuring the cosmic microwave background gravitational lensing potential from 500 deg2 of SPTpol data

    NASA Astrophysics Data System (ADS)

    Mocanu, Laura Monica; South Pole Telescope Collaboration

    2016-06-01

    Weak gravitational lensing by large-scale structure in the universe causes deflections in the paths of cosmic microwave background (CMB) photons. This effect introduces non-Gaussian correlations in the observed CMB temperature and polarization fields. The signature of lensing can be used to reconstruct the projected gravitational lensing potential with a quadratic estimator technique; this provides a measure of the integrated mass distribution out to the surface of last scattering, sourced primarily from redshifts between 0.1 and 5. The power spectrum of the lensing potential encodes information about the geometry of the universe and the growth of structure and can be used to place constraints on the sum of neutrino masses and dark energy. High signal-to-noise mass maps from CMB lensing are also powerful for cross-correlating with other tracers of large-scale structure and for delensing the CMB in search for primordial gravitational waves. This poster will describe recent progress on measuring the CMB gravitational lensing potential and its power spectrum using data from 500 deg2 of sky observed with the polarization-sensitive receiver installed on the South Pole Telescope, SPTpol.

  8. BAYESIAN COMPONENT SEPARATION AND COSMIC MICROWAVE BACKGROUND ESTIMATION FOR THE FIVE-YEAR WMAP TEMPERATURE DATA

    SciTech Connect

    Dickinson, C.; Banday, A. J.; Jewell, J. B.; Gorski, K. M.; Huey, G.; Lawrence, C. R.; O'Dwyer, I. J.; Wandelt, B. D.

    2009-11-10

    A well-tested and validated Gibbs sampling code, that performs component separation and cosmic microwave background (CMB) power spectrum estimation, was applied to the WMAP five-year data. Using a simple model consisting of CMB, noise, monopoles, and dipoles, a 'per pixel' low-frequency power-law (fitting for both amplitude and spectral index), and a thermal dust template with a fixed spectral index, we found that the low-l (l < 50) CMB power spectrum is in good agreement with the published WMAP5 results. Residual monopoles and dipoles were found to be small (approx<3 muK) or negligible in the five-year data. We comprehensively tested the assumptions that were made about the foregrounds (e.g., dust spectral index, power-law spectral index prior, templates), and found that the CMB power spectrum was insensitive to these choices. We confirm the asymmetry of power between the north and south ecliptic hemispheres, which appears to be robust against foreground modeling. The map of low-frequency spectral indices indicates a steeper spectrum on average (beta = -2.97 +- 0.21) relative to those found at low (approxGHz) frequencies.

  9. PARAMETER ESTIMATION FROM IMPROVED MEASUREMENTS OF THE COSMIC MICROWAVE BACKGROUND FROM QUaD

    SciTech Connect

    Gupta, S.; Ade, P.; Bowden, M.; Gear, W. K.; Orlando, A.; Bock, J.; Leitch, E.; Brown, M. L.; Cahill, G.; Murphy, J. A.; Castro, P. G.; Memari, Y.; Church, S.; Hinderks, J.; Culverhouse, T.; Friedman, R. B.; Ganga, K.; Melhuish, S. J.

    2010-06-20

    We evaluate the contribution of cosmic microwave background (CMB) polarization spectra to cosmological parameter constraints. We produce cosmological parameters using high-quality CMB polarization data from the ground-based QUaD experiment and demonstrate for the majority of parameters that there is significant improvement on the constraints obtained from satellite CMB polarization data. We split a multi-experiment CMB data set into temperature and polarization subsets and show that the best-fit confidence regions for the {Lambda}CDM six-parameter cosmological model are consistent with each other, and that polarization data reduces the confidence regions on all parameters. We provide the best limits on parameters from QUaD EE/BB polarization data and we find best-fit parameters from the multi-experiment CMB data set using the optimal pivot scale of k{sub p} = 0.013 Mpc{sup -1} to be {l_brace}h {sup 2{Omega}}{sub c}, h {sup 2{Omega}}{sub b}, H{sub 0}, A{sub s} , n{sub s} , {tau}{r_brace} = {l_brace}0.113, 0.0224, 70.6, 2.29 x 10{sup -9}, 0.960, 0.086{r_brace}.

  10. Measurement of the cosmic microwave background polarization lensing power spectrum with the POLARBEAR experiment.

    PubMed

    Ade, P A R; Akiba, Y; Anthony, A E; Arnold, K; Atlas, M; Barron, D; Boettger, D; Borrill, J; Chapman, S; Chinone, Y; Dobbs, M; Elleflot, T; Errard, J; Fabbian, G; Feng, C; Flanigan, D; Gilbert, A; Grainger, W; Halverson, N W; Hasegawa, M; Hattori, K; Hazumi, M; Holzapfel, W L; Hori, Y; Howard, J; Hyland, P; Inoue, Y; Jaehnig, G C; Jaffe, A; Keating, B; Kermish, Z; Keskitalo, R; Kisner, T; Le Jeune, M; Lee, A T; Linder, E; Leitch, E M; Lungu, M; Matsuda, F; Matsumura, T; Meng, X; Miller, N J; Morii, H; Moyerman, S; Myers, M J; Navaroli, M; Nishino, H; Paar, H; Peloton, J; Quealy, E; Rebeiz, G; Reichardt, C L; Richards, P L; Ross, C; Schanning, I; Schenck, D E; Sherwin, B; Shimizu, A; Shimmin, C; Shimon, M; Siritanasak, P; Smecher, G; Spieler, H; Stebor, N; Steinbach, B; Stompor, R; Suzuki, A; Takakura, S; Tomaru, T; Wilson, B; Yadav, A; Zahn, O

    2014-07-11

    Gravitational lensing due to the large-scale distribution of matter in the cosmos distorts the primordial cosmic microwave background (CMB) and thereby induces new, small-scale B-mode polarization. This signal carries detailed information about the distribution of all the gravitating matter between the observer and CMB last scattering surface. We report the first direct evidence for polarization lensing based on purely CMB information, from using the four-point correlations of even- and odd-parity E- and B-mode polarization mapped over ∼30 square degrees of the sky measured by the POLARBEAR experiment. These data were analyzed using a blind analysis framework and checked for spurious systematic contamination using null tests and simulations. Evidence for the signal of polarization lensing and lensing B modes is found at 4.2σ (stat+sys) significance. The amplitude of matter fluctuations is measured with a precision of 27%, and is found to be consistent with the Lambda cold dark matter cosmological model. This measurement demonstrates a new technique, capable of mapping all gravitating matter in the Universe, sensitive to the sum of neutrino masses, and essential for cleaning the lensing B-mode signal in searches for primordial gravitational waves. PMID:25062161

  11. Cosmic ray/Soft X-ray background relationship from July 1968 to June 1987

    NASA Astrophysics Data System (ADS)

    Jakimiec, M.; Antalova, A.; Storini, M.

    2000-10-01

    The cross-correlation technique has been applied to obtain quantitative information on the short-term relation between the intensity of the nucleonic component of galactic cosmic rays (CR), as recorded by the Calgary neutron monitor, and the solar soft X-ray background (XBG), measured by satellites. The data consisted of uninterrupted daily sequences from July 1968 to June 1987. Using the 12-month basic (b_i), detrended (d_i), the running mean (m_i(n)) and the residual sequences (r_i(n)), where n = 3, 7, 15, 27 days and i = 1,..., 19, the consecutive CR/XBG cross-correlation functions (ccf-s) were computed with a time lag ranging from -2 to +60 days. In 13 cases out of the 19 d_i sequences, a statistically significant anticorrelation was found in the first minimum (for a lag shorter than or equal to 10 days). The m_i and the r_i sequences helped to identify fluctuations on different time scales. In Jakimiec, Antalova and Storini (1999) results for the period July 1968-June 1980 were used to underline differences and analogies between the descending phase of solar activity cycle n. 20 and the ascending phase of solar activity cycle n. 21, i.e., one complete heliomagnetic semicycle. Here we mainly compared the relationship between both parameters during two consecutive descending phases of cycle n. 20 with the one of cycle n. 21.

  12. Rotation of the cosmic microwave background polarization from weak gravitational lensing.

    PubMed

    Dai, Liang

    2014-01-31

    When a cosmic microwave background (CMB) photon travels from the surface of last scatter through spacetime metric perturbations, the polarization vector may rotate about its direction of propagation. This gravitational rotation is distinct from, and occurs in addition to, the lensing deflection of the photon trajectory. This rotation can be sourced by linear vector or tensor metric perturbations and is fully coherent with the curl deflection field. Therefore, lensing corrections to the CMB polarization power spectra as well as the temperature-polarization cross correlations due to nonscalar perturbations are modified. The rotation does not affect lensing by linear scalar perturbations, but needs to be included when calculations go to higher orders. We present complete results for weak lensing of the full-sky CMB power spectra by general linear metric perturbations, taking into account both deflection of the photon trajectory and rotation of the polarization. For the case of lensing by gravitational waves, we show that the B modes induced by the rotation largely cancel those induced by the curl component of deflection. PMID:24580435

  13. Cosmic background radiation in the vicinity of a Schwarzschild black hole: No classic firewall

    NASA Astrophysics Data System (ADS)

    Wielgus, M.; Ellis, G. F. R.; Vincent, F. H.; Abramowicz, M. A.

    2014-12-01

    The cosmic blackbody background radiation pervades the entire Universe, and so falls into every astrophysical black hole. The blueshift of the infalling photons, measured by a static observer, is infinite at the event horizon. This raises a question as to whether a "firewall" of high energy density may form just outside the horizon, or whether the effect can be attributed exclusively to a singular behavior of the static observer's frame at the horizon. In principle, the presence of such a firewall may alter the motion of the infalling matter, influence the black hole evolution, or even invalidate the vacuum Einstein field equation solution as a realistic approximation for black holes. In this paper we show by means of analytic calculations that all these effects indeed exist, but their magnitude is typically negligibly small, even though the matter stress tensor is divergent in the static frame at r =2 M . That is not surprising because of the divergent relation of that frame to a freely falling frame as r →2 M ; however, it represents a kind of classical analogue for the black hole complementarity principle that has been proposed for quantum effects near a black hole. What is perhaps more surprising is the divergence of the radiation stress tensor for massive particles moving on circular geodesic orbits for values of r approaching r =3 M . However such orbits will not occur for infalling matter in realistic accretion discs.

  14. A Instrument and Technique for Measuring the Anisotropy in the Cosmic Microwave Background Radiation

    NASA Astrophysics Data System (ADS)

    Wilson, Grant W.

    1997-09-01

    There is a wealth of information contained in the spatial temperature distribution of the Cosmic Microwave Background Radiation (CMB) >From the pioneering discovery of anisotropy by the COBE satellite to the latest balloon payloads and ground based observations, measurements of the CMB have become the cornerstone of our current understanding of the Universe. Currently, the second generation of CMB experiments are coming on-line. With improved detectors and novel observing strategies, these experiments are destined to make the transition from 'discovering' the anisotropy in the CMB to making precision measurements of the spatial correlation function. Herein I describe the most recent of these second generation experiments: the Medium Scale Anisotropy Measurement (MSAM II). MSAM II is a balloon-based telescope with a bolometric receiver cooled by an Adiabatic Demagnetization Refrigerator to 100 mK. MSAM II samples the sky with a 20 prime FWHM beam swept with a triangle wave at 2.5 Hz and will make a precision measurement of the spatial correlation function from 1 = 100 to 1 = 500. In addition to a comprehensive discussion of the fabrication and development of the cryogenic and optical systems of MSAM II, I present a novel method of estimating cosmological parameters from anisotropy measurements using a maximum Likelihood technique which employs the full covariance matrix of observations. This method has been used on the combined three years of MSAM I datasets to constrain the mass fraction of baryons in the universe, ΩB, as well as a number of other cosmological parameters.

  15. Detection of trans-Planckian effects in the cosmic microwave background

    SciTech Connect

    Groeneboom, Nicolaas E.; Elgaroey, Oystein

    2008-02-15

    Quantum gravity effects are expected to modify the primordial density fluctuations produced during inflation and leave their imprint on the cosmic microwave background observed today. We present a new analysis discussing whether these effects are detectable, considering both currently available data and simulated results from an optimal CMB experiment. We find that the WMAP (Wilkinson Microwave Anisotropy Probe) data show no evidence for the particular signature considered in this work but give an upper bound on the parameters of the model. However, a hypothetical experiment shows that with proper data, the trans-Planckian effects should be detectable through alternate sampling methods. This fuzzy conclusion is a result of the nature of the oscillations, since they give rise to a likelihood hypersurface riddled with local maxima. A simple Bayesian analysis shows no significant evidence for the simulated data to prefer a trans-Planckian model. Conventional Markov chain Monte Carlo (MCMC) methods are not suitable for exploring this complicated landscape, but alternative methods are required to solve the problem. This, however, requires extremely high-precision data.

  16. IMPACTS OF DARK STARS ON REIONIZATION AND SIGNATURES IN THE COSMIC MICROWAVE BACKGROUND

    SciTech Connect

    Scott, Pat; Roebber, Elinore; Holder, Gil; Venkatesan, Aparna; Gondolo, Paolo; Pierpaoli, Elena E-mail: avenkatesan@usfca.edu

    2011-12-01

    We perform a detailed and systematic investigation of the possible impacts of dark stars on the reionization history of the universe, and its signatures in the cosmic microwave background (CMB). We compute hydrogen reionization histories, CMB optical depths, and anisotropy power spectra for a range of stellar populations including dark stars. If dark stars capture large amounts of dark matter (DM) via nuclear scattering, reionization can be substantially delayed, leading to decreases in the integrated optical depth to last scattering and large-scale power in the EE polarization power spectrum. Using the integrated optical depth observed by the Wilkinson Microwave Anistropy Probe seven-year mission, in our canonical reionization model we rule out the section of parameter space where dark stars with high scattering-induced capture rates tie up {approx}> 90% of all the first star-forming baryons, and live for {approx}> 250 Myr. When nuclear scattering delivers only moderate amounts of DM, reionization can instead be sped up slightly, modestly increasing the CMB optical depth. If dark stars do not obtain any DM via nuclear scattering, effects on reionization and the CMB are negligible. The effects of dark stars on reionization and its CMB markers can be largely mimicked or compensated for by changes in the existing parameters of reionization models, making dark stars difficult to disentangle from astrophysical uncertainties, but also widening the range of standard parameters in reionization models that can be made consistent with observations.

  17. Detecting Gravitational Lensing of the Cosmic Microwave Background by Galaxy Clusters

    SciTech Connect

    Baxter, Eric Jones

    2014-08-01

    Clusters of galaxies gravitationally lens the Cosmic Microwave Background (CMB) leading to a distinct signal in the CMB on arcminute scales. Measurement of the cluster lensing effect offers the exciting possibility of constraining the masses of galaxy clusters using CMB data alone. Improved constraints on cluster masses are in turn essential to the use of clusters as cosmological probes: uncertainties in cluster masses are currently the dominant systematic affecting cluster abundance constraints on cosmology. To date, however, the CMB cluster lensing signal remains undetected because of its small magnitude and angular size. In this thesis, we develop a maximum likelihood approach to extracting the signal from CMB temperature data. We validate the technique by applying it to mock data designed to replicate as closely as possible real data from the South Pole Telescope’s (SPT) Sunyaev-Zel’dovich (SZ) survey: the effects of the SPT beam, transfer function, instrumental noise and cluster selection are incorporated. We consider the effects of foreground emission on the analysis and show that uncertainty in amount of foreground lensing results in a small systematic error on the lensing constraints. Additionally, we show that if unaccounted for, the SZ effect leads to unacceptably large biases on the lensing constraints and develop an approach for removing SZ contamination. The results of the mock analysis presented here suggest that a 4σ first detection of the cluster lensing effect can be achieved with current SPT-SZ data.

  18. Measurement of the Cosmic Microwave Background Polarization Lensing Power Spectrum with the POLARBEAR Experiment

    NASA Astrophysics Data System (ADS)

    Ade, P. A. R.; Akiba, Y.; Anthony, A. E.; Arnold, K.; Atlas, M.; Barron, D.; Boettger, D.; Borrill, J.; Chapman, S.; Chinone, Y.; Dobbs, M.; Elleflot, T.; Errard, J.; Fabbian, G.; Feng, C.; Flanigan, D.; Gilbert, A.; Grainger, W.; Halverson, N. W.; Hasegawa, M.; Hattori, K.; Hazumi, M.; Holzapfel, W. L.; Hori, Y.; Howard, J.; Hyland, P.; Inoue, Y.; Jaehnig, G. C.; Jaffe, A.; Keating, B.; Kermish, Z.; Keskitalo, R.; Kisner, T.; Le Jeune, M.; Lee, A. T.; Linder, E.; Leitch, E. M.; Lungu, M.; Matsuda, F.; Matsumura, T.; Meng, X.; Miller, N. J.; Morii, H.; Moyerman, S.; Myers, M. J.; Navaroli, M.; Nishino, H.; Paar, H.; Peloton, J.; Quealy, E.; Rebeiz, G.; Reichardt, C. L.; Richards, P. L.; Ross, C.; Schanning, I.; Schenck, D. E.; Sherwin, B.; Shimizu, A.; Shimmin, C.; Shimon, M.; Siritanasak, P.; Smecher, G.; Spieler, H.; Stebor, N.; Steinbach, B.; Stompor, R.; Suzuki, A.; Takakura, S.; Tomaru, T.; Wilson, B.; Yadav, A.; Zahn, O.; Polarbear Collaboration

    2014-07-01

    Gravitational lensing due to the large-scale distribution of matter in the cosmos distorts the primordial cosmic microwave background (CMB) and thereby induces new, small-scale B-mode polarization. This signal carries detailed information about the distribution of all the gravitating matter between the observer and CMB last scattering surface. We report the first direct evidence for polarization lensing based on purely CMB information, from using the four-point correlations of even- and odd-parity E- and B-mode polarization mapped over ˜30 square degrees of the sky measured by the POLARBEAR experiment. These data were analyzed using a blind analysis framework and checked for spurious systematic contamination using null tests and simulations. Evidence for the signal of polarization lensing and lensing B modes is found at 4.2σ (stat +sys) significance. The amplitude of matter fluctuations is measured with a precision of 27%, and is found to be consistent with the Lambda cold dark matter cosmological model. This measurement demonstrates a new technique, capable of mapping all gravitating matter in the Universe, sensitive to the sum of neutrino masses, and essential for cleaning the lensing B-mode signal in searches for primordial gravitational waves.

  19. EVIDENCE OF QUASI-LINEAR SUPER-STRUCTURES IN THE COSMIC MICROWAVE BACKGROUND AND GALAXY DISTRIBUTION

    SciTech Connect

    Inoue, Kaiki Taro; Sakai, Nobuyuki; Tomita, Kenji

    2010-11-20

    Recent measurements of hot and cold spots on the cosmic microwave background (CMB) sky suggest the presence of super-structures on (>100 h {sup -1} Mpc) scales. We develop a new formalism to estimate the expected amplitude of temperature fluctuations due to the integrated Sachs-Wolfe (ISW) effect from prominent quasi-linear structures. Applying the developed tools to the observed ISW signals from voids and clusters in catalogs of galaxies at redshifts z < 1, we find that they indeed imply a presence of quasi-linear super-structures with a comoving radius of 100 {approx} 300 h {sup -1} Mpc and a density contrast |{delta}| {approx} O(0.1). We also find that the observed ISW signals are at odds with the concordant {Lambda} cold dark matter model that predicts Gaussian primordial perturbations at {approx}>3{sigma} level. We confirm that the mean temperature around the CMB cold spot in the southern Galactic hemisphere filtered by a compensating top-hat filter deviates from the mean value at {approx}3{sigma} level, implying that a quasi-linear supervoid or an underdensity region surrounded by a massive wall may reside at low redshifts z < 0.3 and the actual angular size (16{sup 0}-17{sup 0}) may be larger than the apparent size (4{sup 0}-10{sup 0}) discussed in literature. Possible solutions are briefly discussed.

  20. Fault tolerant capabilities of the Cosmic Background Explorer attitude control system

    NASA Technical Reports Server (NTRS)

    Placanica, Samuel J.

    1992-01-01

    The Cosmic Background Explorer (COBE), which was launched November 18, 1989 from Vandenberg Air Force Base aboard a Delta rocket, has been classified by the scientific community as a major success with regards to the field of cosmology theory. Despite a number of anomalies which have occurred during the mission, the attitude control system (ACS) has performed remarkably well. This is due in large part to the fault tolerant capabilities that were designed into the ACS. A unique triaxial control system orientated in the spacecraft's transverse plane provides the ACS the ability to safely survive various sensor and actuator failures. Features that help to achieve this fail-operational system include component cross-strapping and autonomous control electronics switching. This design philosophy was of utmost importance because of the constraint placed upon the ACS to keep the spinning observatory and its cryogen-cooled science instruments pointing away from the sun. Even though the liquid helium was depleted within the expected twelve months from launch, it is still very much desirable to avoid any thermal disturbances upon the remaining functional instruments.

  1. MAXIMUM LIKELIHOOD ANALYSIS OF SYSTEMATIC ERRORS IN INTERFEROMETRIC OBSERVATIONS OF THE COSMIC MICROWAVE BACKGROUND

    SciTech Connect

    Zhang Le; Timbie, Peter; Karakci, Ata; Korotkov, Andrei; Tucker, Gregory S.; Sutter, Paul M.; Wandelt, Benjamin D.; Bunn, Emory F.

    2013-06-01

    We investigate the impact of instrumental systematic errors in interferometric measurements of the cosmic microwave background (CMB) temperature and polarization power spectra. We simulate interferometric CMB observations to generate mock visibilities and estimate power spectra using the statistically optimal maximum likelihood technique. We define a quadratic error measure to determine allowable levels of systematic error that does not induce power spectrum errors beyond a given tolerance. As an example, in this study we focus on differential pointing errors. The effects of other systematics can be simulated by this pipeline in a straightforward manner. We find that, in order to accurately recover the underlying B-modes for r = 0.01 at 28 < l < 384, Gaussian-distributed pointing errors must be controlled to 0. Degree-Sign 7 root mean square for an interferometer with an antenna configuration similar to QUBIC, in agreement with analytical estimates. Only the statistical uncertainty for 28 < l < 88 would be changed at {approx}10% level. With the same instrumental configuration, we find that the pointing errors would slightly bias the 2{sigma} upper limit of the tensor-to-scalar ratio r by {approx}10%. We also show that the impact of pointing errors on the TB and EB measurements is negligibly small.

  2. Development of Readout Electronics for POLARBEAR-2 Cosmic Microwave Background Experiment

    NASA Astrophysics Data System (ADS)

    Hattori, K.; Akiba, Y.; Arnold, K.; Barron, D.; Bender, A. N.; Cukierman, A.; de Haan, T.; Dobbs, M.; Elleflot, T.; Hasegawa, M.; Hazumi, M.; Holzapfel, W.; Hori, Y.; Keating, B.; Kusaka, A.; Lee, A.; Montgomery, J.; Rotermund, K.; Shirley, I.; Suzuki, A.; Whitehorn, N.

    2016-07-01

    The readout of transition-edge sensor (TES) bolometers with a large multiplexing factor is key for the next generation cosmic microwave background (CMB) experiment, Polarbear-2 (Suzuki in J Low Temp Phys 176:719, 2014), having 7588 TES bolometers. To enable the large arrays, we have been developing a readout system with a multiplexing factor of 40 in the frequency domain. Extending that architecture to 40 bolometers requires an increase in the bandwidth of the SQUID electronics, above 4 MHz. This paper focuses on cryogenic readout and shows how it affects cross talk and the responsivity of the TES bolometers. A series resistance, such as equivalent series resistance of capacitors for LC filters, leads to non-linear response of the bolometers. A wiring inductance modulates a voltage across the bolometers and causes cross talk. They should be controlled well to reduce systematic errors in CMB observations. We have been developing a cryogenic readout with a low series impedance and have tuned bolometers in the middle of their transition at a high frequency (>3 MHz).

  3. Development of Readout Electronics for uc(POLARBEAR-2) Cosmic Microwave Background Experiment

    NASA Astrophysics Data System (ADS)

    Hattori, K.; Akiba, Y.; Arnold, K.; Barron, D.; Bender, A. N.; Cukierman, A.; de Haan, T.; Dobbs, M.; Elleflot, T.; Hasegawa, M.; Hazumi, M.; Holzapfel, W.; Hori, Y.; Keating, B.; Kusaka, A.; Lee, A.; Montgomery, J.; Rotermund, K.; Shirley, I.; Suzuki, A.; Whitehorn, N.

    2016-01-01

    The readout of transition-edge sensor (TES) bolometers with a large multiplexing factor is key for the next generation cosmic microwave background (CMB) experiment, uc(Polarbear)-2 (Suzuki in J Low Temp Phys 176:719, 2014), having 7588 TES bolometers. To enable the large arrays, we have been developing a readout system with a multiplexing factor of 40 in the frequency domain. Extending that architecture to 40 bolometers requires an increase in the bandwidth of the SQUID electronics, above 4 MHz. This paper focuses on cryogenic readout and shows how it affects cross talk and the responsivity of the TES bolometers. A series resistance, such as equivalent series resistance of capacitors for LC filters, leads to non-linear response of the bolometers. A wiring inductance modulates a voltage across the bolometers and causes cross talk. They should be controlled well to reduce systematic errors in CMB observations. We have been developing a cryogenic readout with a low series impedance and have tuned bolometers in the middle of their transition at a high frequency (> 3 MHz).

  4. Constraining the Redshift Evolution of the Cosmic Microwave Background Blackbody Temperature with PLANCK Data.

    NASA Astrophysics Data System (ADS)

    de Martino, I.; Génova-Santos, R.; Atrio-Barandela, F.; Ebeling, H.; Kashlinsky, A.; Kocevski, D.; Martins, C. J. A. P.

    2015-08-01

    We constrain the deviation of adiabatic evolution of the universe using the data on the cosmic microwave background (CMB) temperature anisotropies measured by the Planck satellite and a sample of 481 X-ray selected clusters with spectroscopically measured redshifts. To avoid antenna beam effects, we bring all of the maps to the same resolution. We use a CMB template to subtract the cosmological signal while preserving the Thermal Sunyaev-Zeldovich (TSZ) anisotropies; next, we remove galactic foreground emissions around each cluster and we mask out all known point sources. If the CMB blackbody temperature scales with redshift as T{(z)={T}0(1+z)}1-α , we constrain deviations of adiabatic evolution to be α = -0.007 ± 0.013, consistent with the temperature-redshift relation of the standard cosmological model. This result could suffer from a potential bias δα associated with the CMB template. We quantify it to be | δ α | ≤slant 0.02, with the same sign as the measured value of α. Our result is free from those biases associated with using TSZ selected clusters; it represents the best constraint to date of the temperature-redshift relation of the Big Bang model using only CMB data, confirming previous results.

  5. VizieR Online Data Catalog: WMAP cosmic microwave background data (Rassat+, 2013)

    NASA Astrophysics Data System (ADS)

    Rassat, A.; Starck, J.-L.

    2013-08-01

    There is currently a debate over the existence of claimed statistical anomalies in the cosmic microwave background (CMB), recently confirmed in Planck data. Recent work has focussed on methods for measuring statistical significance, on masks and on secondary anisotropies as potential causes of the anomalies. We investigate simultaneously the method for accounting for masked regions and the foreground integrated Sachs-Wolfe (ISW) signal. We search for trends in different years of WMAP CMB data with different mask treatments. We reconstruct the ISW field due to the 2 Micron All-Sky Survey (2MASS) and the NRAO VLA Sky Survey (NVSS) up to l=5, and we focus on the Axis of Evil (AoE) statistic and even/odd mirror parity, both of which search for preferred axes in the Universe. We find that removing the ISW reduces the significance of these anomalies in WMAP data, though this does not exclude the possibility of exotic physics. In the spirit of reproducible research, all reconstructed maps and codes will be made available for download at http://www.cosmostat.org/anomaliesCMB.html . (3 data files).

  6. Constraints on Dark Matter Interactions with Standard Model Particles from Cosmic Microwave Background Spectral Distortions.

    PubMed

    Ali-Haïmoud, Yacine; Chluba, Jens; Kamionkowski, Marc

    2015-08-14

    We propose a new method to constrain elastic scattering between dark matter (DM) and standard model particles in the early Universe. Direct or indirect thermal coupling of nonrelativistic DM with photons leads to a heat sink for the latter. This results in spectral distortions of the cosmic microwave background (CMB), the amplitude of which can be as large as a few times the DM-to-photon-number ratio. We compute CMB spectral distortions due to DM-proton, DM-electron, and DM-photon scattering for generic energy-dependent cross sections and DM mass m_{χ}≳1 keV. Using Far-Infrared Absolute Spectrophotometer measurements, we set constraints on the cross sections for m_{χ}≲0.1 MeV. In particular, for energy-independent scattering we obtain σ_{DM-proton}≲10^{-24} cm^{2} (keV/m_{χ})^{1/2}, σ_{DM-electron}≲10^{-27} cm^{2} (keV/m_{χ})^{1/2}, and σ_{DM-photon}≲10^{-39} cm^{2} (m_{χ}/keV). An experiment with the characteristics of the Primordial Inflation Explorer would extend the regime of sensitivity up to masses m_{χ}~1 GeV. PMID:26317709

  7. The Cosmic Microwave Background Radiation does NOT prove that the Hot Big Bang Theory is Correct

    NASA Astrophysics Data System (ADS)

    Bligh, B. R.

    2009-12-01

    It has frequently been asserted that the discovery of the Cosmic Microwave Background Radiation (CMB) by Penzias and Wilson is proof of the validity of the Hot Big Bang Theory of the origin of the Universe. In reality this is not the case because the expansion of the Universe at the time of the supposed "Fireball'' would not produce the perfect black-body radiation which is actually observed. This problem with the CMB has been pointed out before by Mitchell (1994) but the present study establishes the argument by means of rigorous thermodynamic calculations. The CMB is said to have been produced at the time of"de-coupling'' when the electron density in the primeval Universe was very small. The radiation generated at that epoch would have had a black-body spectrum. Three cases are analysed when the electron density approached zero; three appropriate temperatures are taken and then the thermodynamic properties -- including density -- are calculated for the three cases. These provide a measure of the expansion to the present day. Wien's law is applied to calculate the fall in temperature of the radiation for each case -- assuming that the black-body spectrum is maintained. According to the Hot Big Bang Theory the three cases should all arrive at 2.72 K, but they do not. The conclusion is that the CMB spectrum ought to be "smeared" and not the almost perfect black-body curve, which is actually observed. Therefore the Hot Big Bang Theory fails this test.

  8. Uniformity of cosmic microwave background as a non-inflationary geometrical effect

    NASA Astrophysics Data System (ADS)

    Vlahovic, Branislav; Eingorn, Maxim; Ilie, Cosmin

    2015-10-01

    The conventional ΛCDM cosmological model supplemented by the inflation concept describes the Universe very well. However, there are still a few concerns: new Planck data impose constraints on the shape of the inflaton potential, which exclude a lot of inflationary models; dark matter is not detected directly, and dark energy is not understood theoretically on a satisfactory level. In this brief sketch, we investigate an alternative cosmological model with spherical spatial geometry and an additional perfect fluid with the constant parameter ω = -1/3 in the linear equation of state. It is demonstrated explicitly that in the framework of such a model it is possible to satisfy the supernovae data at the same level of accuracy as within the ΛCDM model and at the same time suppose that the observed cosmic microwave background (CMB) radiation originates from a very limited space region. This is ensured by introducing an additional condition of light propagation between the antipodal points during the age of the Universe. Consequently, the CMB uniformity can be explained without the inflation scenario. The corresponding drawbacks of the model with respect to its comparison with the CMB data are also discussed.

  9. Using Wavelet Transforms to Detect Dust in Cosmic Microwave Background Maps

    NASA Astrophysics Data System (ADS)

    Rybolt, Ben; Guest, S.; Larson, G.; Bunn, E.

    2008-05-01

    A major question regarding temperature fluctuations in the cosmic microwave background (CMB) is whether or not they obey Gaussian statistics (i.e., whether they contain any additional information beyond that contained in the power spectrum). Inflation predicts that the CMB is Gaussian; future experiments will test this prediction. Dust contamination will likely be a problem for these tests, and could bias the results, as dust is known to be highly non-Gaussian. We are developing statistical test to detect dust contamination. It has previously been shown that wavelet transforms efficiently represent dust, so we compare the power of a variety of statistical tests to maps with and without wavelet transforms. Some statistics we have looked at are the skewness, linear correlations between a simulated map and a dust template, and a comparison of the mean-square signal in high-dust and low-dust regions. We have found that using a wavelet transform does not help detect dust for the skewness test, but it significantly increases the power of the mean-square test. This research is supported by grants from the National Science Foundation and the Research Corporation.

  10. Measurements of the cosmic microwave background temperature at 1. 47 GHz

    SciTech Connect

    Bensadoun, M.J.

    1991-11-01

    A radiofrequency-gain total power radiometer measured the intensity of the cosmic microwave background (CMB) at a frequency of 1.47 GHz (20.4 cm wavelength) from White Mountain, California, in September 1988 and from the South Pole, Antarctica, in December 1989. The CMB thermodynamic temperature, TCMB, is 2.27 {plus minus} 0.25 K (68% C.L.) measured from White Mountain and 2.26 {plus minus} 0.21 K from the South Pole site. The combined result is 2.27 {plus minus} 0.19 K. The correction for galactic emission has been derived from scaled low-frequency maps and constitutes the main source, of error. The atmospheric signal is found by extrapolation from zenith scan measurements at higher frequencies. The result is consistent with previous low-frequency measurements, including a measurement at 1.41 GHz (Levin et al. 1988) made with an earlier version of this instrument. The result is {approximately}2.5 {sigma} ({approximately}l% probability) from the 2.74 {plus minus} 0.02,K global average CMB temperature.

  11. Measurements of the cosmic microwave background temperature at 1.47 GHz

    SciTech Connect

    Bensadoun, M.J.

    1991-11-01

    A radiofrequency-gain total power radiometer measured the intensity of the cosmic microwave background (CMB) at a frequency of 1.47 GHz (20.4 cm wavelength) from White Mountain, California, in September 1988 and from the South Pole, Antarctica, in December 1989. The CMB thermodynamic temperature, TCMB, is 2.27 {plus_minus} 0.25 K (68% C.L.) measured from White Mountain and 2.26 {plus_minus} 0.21 K from the South Pole site. The combined result is 2.27 {plus_minus} 0.19 K. The correction for galactic emission has been derived from scaled low-frequency maps and constitutes the main source, of error. The atmospheric signal is found by extrapolation from zenith scan measurements at higher frequencies. The result is consistent with previous low-frequency measurements, including a measurement at 1.41 GHz (Levin et al. 1988) made with an earlier version of this instrument. The result is {approximately}2.5 {sigma} ({approximately}l% probability) from the 2.74 {plus_minus} 0.02,K global average CMB temperature.

  12. MAXIMA: an experiment to measure temperature anisotropy in the cosmic microwave background

    SciTech Connect

    Lee, A.T.; Balbi, A.; Borrill, J.; Jaffe, A.H.; Oh, S.; Rabii, B.; Richards, P.L.; Smoot, G.F.; Winant, C.D.; Lee, A.T.; Jaffe, A.H.; Rabii, B.; Richards, P.L.; Smoot, G.F.; Winant, C.D.; Ade, P.; Hristov, V.; Lange, A.E.; Pascale, E.; Balbi, A.; Borrill, J.; Bock, J.; Crill, B.P.; Smoot, G.F.; Bock, J.; Del Castillo, H.; Boscaleri, A.; De Bernardis, P.; Ferreira, P.; Ganga, K.; Hanany, S.; Mauskopf, P.; Netterfield, C.B.; Ruhl, J.

    1999-05-01

    We describe the MAXIMA experiment, a balloon-borne measurement designed to map temperature anisotropy in the Cosmic Microwave Background (CMB) from l=80 to l=800. The experiment consists of a 1.3 m diameter off-axis Gregorian telescope and a receiver with a 16 element array of bolometers cooled to 100 mK. The frequency bands are centered at 150, 240, and 410 GHz. The 10{sup {prime}} FWHM beam sizes are well matched to the scale of acoustic peaks expected in the angular power spectrum of the CMB. The first flight of the experiment in its full configuration was launched in August 1998. A 122 deg{sup 2} map of the sky was made near the Draco constellation during the 7 hour flight in a region of extremely low galactic dust contamination. This map covers 0.3{percent} of the sky and has 3200 independent beamsize pixels. We describe the MAXIMA instrument and its performance during the recent flight. {copyright} {ital 1999 American Institute of Physics.}

  13. LOCAL NON-GAUSSIANITY IN THE COSMIC MICROWAVE BACKGROUND THE BAYESIAN WAY

    SciTech Connect

    Elsner, Franz; Wandelt, Benjamin D.

    2010-12-01

    We introduce an exact Bayesian approach to search for non-Gaussianity of local type in cosmic microwave background (CMB) radiation data. Using simulated CMB temperature maps, the newly developed technique is compared against the conventional frequentist bispectrum estimator. Starting from the joint probability distribution, we obtain analytic expressions for the conditional probabilities of the primordial perturbations given the data, and for the level of non-Gaussianity, f{sub NL}, given the data and the perturbations. We propose Hamiltonian Monte Carlo sampling as a means to derive realizations of the primordial fluctuations from which we in turn sample f{sub NL}. Although computationally expensive, this approach allows us to construct exactly the full target posterior probability distribution. When compared to the frequentist estimator, applying the Bayesian method to Gaussian CMB maps provides consistent results. For the analysis of non-Gaussian maps, however, the error bars on f{sub NL} do not show excess variance within the Bayesian framework. This finding is of particular relevance in the light of upcoming high-precision CMB measurements obtained by the Planck satellite mission.

  14. The cosmic web and microwave background fossilize the first turbulent combustion

    NASA Astrophysics Data System (ADS)

    Gibson, Carl H.

    2015-09-01

    The weblike structure of the cosmic microwave background CMB temperature fluctuations are interpreted as fossils of the first turbulent combustion that drives the big bang1,2,3. Modern turbulence theory3 requires that inertial vortex forces cause turbulence to always cascade from small scales to large, contrary to the standard turbulence model where the cascade is reversed. Assuming that the universe begins at Planck length 10-35 m and temperature 1032 K, the mechanism of the big bang is a powerful turbulent combustion instability, where turbulence forms at the Kolmogorov scale and mass-energy is extracted by < -10113 Pa negative stresses from big bang turbulence working against gravity. Prograde accretion of a Planck antiparticle on a spinning particle-antiparticle pair releases 42% of a particle rest mass from the Kerr metric, producing a spinning gas of turbulent Planck particles that cascades to larger scales at smaller temperatures (10-27 m, 1027 K) retaining the Planck density 1097 kg m-3, where quarks form and gluon viscosity fossilizes the turbulence. Viscous stress powers inflation to ~ 10 m and ~ 10100 kg. The CMB shows signatures of both plasma and big bang turbulence. Direct numerical simulations support the new turbulence theory6.

  15. The imprint of proper motion of nonlinear structures on the cosmic microwave background

    NASA Technical Reports Server (NTRS)

    Tuluie, Robin; Laguna, Pablo

    1995-01-01

    We investigate the imprint of nonlinear matter condensations on the cosmic microwave background (CMB) in an Omega = 1, cold dark matter (CDM) model universe. Temperature anisotropies are obtained by numerically evolving matter inhomogeneities and CMB photons from the beginning of decoupling until the present epoch. The underlying density field produced by the inhomogeneities is followed from the linear, through the weakly clustered, into the fully nonlinear regime. We concentrate on CMB temperature distortions arising from variations in the gravitational potentials of nonlinear structures. We find two sources of temperature fluctuations produced by time-varying potentials: (1) anisotropies due to intrinsic changes in the gravitational potentials of the inhomogeneities and (2) anisotropies generated by the peculiar, bulk motion of the structures across the microwave sky. Both effects generate CMB anisotropies in the range of 10(exp -7) approximately less than or equal to (Delta T/T) approximately less than or equal to 10(exp -6) on scales of approximately 1 deg. For isolated structures, anisotropies due to proper motion exhibit a dipole-like signature in the CMB sky that in principle could yield information on the transverse velocity of the structures.

  16. A FOREGROUND-CLEANED COSMIC MICROWAVE BACKGROUND MAP FROM NON-GAUSSIANITY MEASUREMENT

    SciTech Connect

    Saha, Rajib

    2011-10-01

    In this Letter, we present a new method to estimate a foreground-cleaned cosmic microwave background (CMB) map at a resolution of 1{sup 0} by minimizing the non-Gaussian properties of the cleaned map which arise dominantly due to diffuse foreground emission components from the Milky Way. We employ simple kurtosis statistic as the measure of non-Gaussian properties and perform a linear combination of five frequency maps provided by the Wilkinson Microwave Anisotropy Probe (WMAP) in its seven-year data release in such a way that the cleaned map has a minimum kurtosis which leads to a non-Gaussianity-minimized, foreground-cleaned CMB map. We validate the method by performing Monte Carlo simulations. To minimize any residual foreground contamination from the cleaned map we flag out the region near the galactic plane based upon results from simulations. Outside the masked region our new estimate of the CMB map matches well with the WMAP's Internal Linear Combination (ILC) map. A simple pseudo-C{sub l} -based CMB TT power spectrum derived from the non-Gaussianity minimized map reproduces the earlier results of WMAP's power spectrum. An important advantage of the method is that it does not introduce any negative bias in angular power spectrum in the low multipole regime, unlike usual ILC method. Comparing our results with the previously published results we argue that CMB results are robust with respect to specific foreground removal algorithms employed.

  17. A test of an alternative origin of the cosmic microwave background anisotropy

    NASA Astrophysics Data System (ADS)

    Hsu, Jong-Ping; Hsu, Leonardo

    The dipole anisotropy of the cosmic microwave background (CMB) is usually attributed to the motion of the solar system relative to the CMB. However, such an interpretation requires that the Planck distribution P(ω, T) be non-Lorentz invariant. We discuss an alternative interpretation called the `Big Jets' model, based on a Lorentz-invariant blackbody distribution B(kλUλ/Tinv), which reduces to the Planck distribution in the non-relativistic limit. This model, which implies that the CMB anisotropy must originate from a real, physical anisotropy of the universe, can be tested by examining the shape of the invariant blackbody distribution B(kλUλ/Tinv) and the dipole spectrum as measured by the COBE, WMAP, and Planck satellite experiments. The Big Jets model (a) provides a way to restore matter-antimatter symmetry in the universe by proposing that instead of a big bang, the universe began with two big jets, one with more matter and one with more anti-matter, and (b) suggests that it is the remnant of the anti-matter jet, detectable only as an extremely distant blackbody, that produces the observed CMB dipole anisotropy.

  18. Degree-scale Cosmic Microwave Background Polarization Measurements from Three Years of BICEP1 Data

    NASA Astrophysics Data System (ADS)

    Barkats, D.; Aikin, R.; Bischoff, C.; Buder, I.; Kaufman, J. P.; Keating, B. G.; Kovac, J. M.; Su, M.; Ade, P. A. R.; Battle, J. O.; Bierman, E. M.; Bock, J. J.; Chiang, H. C.; Dowell, C. D.; Duband, L.; Filippini, J.; Hivon, E. F.; Holzapfel, W. L.; Hristov, V. V.; Jones, W. C.; Kuo, C. L.; Leitch, E. M.; Mason, P. V.; Matsumura, T.; Nguyen, H. T.; Ponthieu, N.; Pryke, C.; Richter, S.; Rocha, G.; Sheehy, C.; Kernasovskiy, S. S.; Takahashi, Y. D.; Tolan, J. E.; Yoon, K. W.

    2014-03-01

    BICEP1 is a millimeter-wavelength telescope designed specifically to measure the inflationary B-mode polarization of the cosmic microwave background at degree angular scales. We present results from an analysis of the data acquired during three seasons of observations at the South Pole (2006-2008). This work extends the two-year result published in Chiang et al., with additional data from the third season and relaxed detector-selection criteria. This analysis also introduces a more comprehensive estimation of band power window functions, improved likelihood estimation methods, and a new technique for deprojecting monopole temperature-to-polarization leakage that reduces this class of systematic uncertainty to a negligible level. We present maps of temperature, E- and B-mode polarization, and their associated angular power spectra. The improvement in the map noise level and polarization spectra error bars are consistent with the 52% increase in integration time relative to Chiang et al. We confirm both self-consistency of the polarization data and consistency with the two-year results. We measure the angular power spectra at 21 <= l <= 335 and find that the EE spectrum is consistent with Lambda cold dark matter cosmology, with the first acoustic peak of the EE spectrum now detected at 15σ. The BB spectrum remains consistent with zero. From B-modes only, we constrain the tensor-to-scalar ratio to r = 0.03^{+0.27}_{-0.23}, or r < 0.70 at 95% confidence level.

  19. High-precision simulations of the weak lensing effect on cosmic microwave background polarization

    NASA Astrophysics Data System (ADS)

    Fabbian, Giulio; Stompor, Radek

    2013-08-01

    We studied the accuracy, robustness, and self-consistency of pixel-domain simulations of the gravitational lensing effect on the primordial cosmic microwave background (CMB) anisotropies due to the large-scale structure of the Universe. In particular, we investigated the dependence of the precision of the results precision on some crucial parameters of these techniques and propose a semi-analytic framework to determine their values so that the required precision is a priori assured and the numerical workload simultaneously optimized. Our focus was on the B-mode signal, but we also discuss other CMB observables, such as the total intensity, T, and E-mode polarization, emphasizing differences and similarities between all these cases. Our semi-analytic considerations are backed up by extensive numerical results. Those are obtained using a code, nicknamed lenS2HAT - for lensing using scalable spherical harmonic transforms (S2HAT) - which we have developed in the course of this work. The code implements a version of the previously described pixel-domain approach and permits performing the simulations at very high resolutions and data volumes, thanks to its efficient parallelization provided by the S2HAT library - a parallel library for calculating of the spherical harmonic transforms. The code is made publicly available.

  20. Test facility requirements for the thermal vacuum thermal balance test of the Cosmic Background Explorer Observatory

    NASA Technical Reports Server (NTRS)

    Milam, Laura J.

    1991-01-01

    The Cosmic Background Explorer Observatory (COBE) underwant a thermal vacuum thermal balance test in the Space Environment Simulator (SES). This was the largest and most complex test ever conducted at this facility. The 4 x 4 m (13 x 13 ft) spacecraft weighed approx. 2223 kg (4900 lbs) for the test. The test set up included simulator panels for the inboard solar array panels, simulator panels for the flight cowlings, Sun and Earth Sensor stimuli, Thermal Radio Frequency Shield heater stimuli and a cryopanel for thermal control in the Attitude Control System Shunt Dissipator area. The fixturing also included a unique 4.3 m (14 ft) diameter Gaseous Helium Cryopanel which provided a 20 K environment for the calibration of one of the spacecraft's instruments, the Differential Microwave Radiometer. This cryogenic panel caused extra contamination concerns and a special method was developed and written into the test procedure to prevent the high buildup of condensibles on the panel which could have led to backstreaming of the thermal vacuum chamber. The test was completed with a high quality simulated space environment provided to the spacecraft. The test requirements, test set up, and special fixturing are described.

  1. Cosmic microwave background reconstruction from WMAP and Planck PR2 data

    NASA Astrophysics Data System (ADS)

    Bobin, J.; Sureau, F.; Starck, J.-L.

    2016-06-01

    We describe a new estimate of the cosmic microwave background (CMB) intensity map reconstructed by a joint analysis of the full Planck 2015 data (PR2) and nine years of WMAP data. The proposed map provides more than a mere update of the CMB map introduced in a previous paper since it benefits from an improvement of the component separation method L-GMCA (Local-Generalized Morphological Component Analysis), which facilitates efficient separation of correlated components. Based on the most recent CMB data, we further confirm previous results showing that the proposed CMB map estimate exhibits appealing characteristics for astrophysical and cosmological applications: i) it is a full-sky map as it did not require any inpainting or interpolation postprocessing; ii) foreground contamination is very low even on the galactic center; and iii) the map does not exhibit any detectable trace of thermal Sunyaev-Zel'dovich contamination. We show that its power spectrum is in good agreement with the Planck PR2 official theoretical best-fit power spectrum. Finally, following the principle of reproducible research, we provide the codes to reproduce the L-GMCA, which makes it the only reproducible CMB map. The reconstructed CMB map and the code are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/591/A50

  2. Use of superconducting bearings to measure the polarization of the cosmic microwave background radiation.

    SciTech Connect

    Hanany, S.; Matsumura, T.; Johnson, B.; Jones, T.; Hull, J. R.; Ma, K. B.

    2002-08-21

    Measurements of the polarization of the cosmic microwave background (CMB) radiation are expected to significantly increase our understanding of the early universe. We present a design for a CMB polarimeter in which a cryogenically cooled half wave plate rotates by means of a high-temperature superconducting (HTS) bearing. The design is optimized for implementation in MAXIPOL, a balloon-borne CMB polarimeter. A prototype bearing, consisting of commercially available ring-shaped permanent magnet and an array of YBCO bulk HTS material, has been constructed. We report on measurements of the coefficient of friction as a function of temperature between 15 and 80 K, of rotation frequency between 0.3 and 3.5 Hz, of levitation distance between 6 and 10 mm, and of ambient pressure between 1 and 10{sup -7} torr. The low rotational drag of the HTS bearing allows rotations for long periods of time with minimal input power and negligible wear and tear thus making this technology suitable for a future satellite mission.

  3. Detection of polarization in the cosmic microwave background using DASI. Degree Angular Scale Interferometer.

    PubMed

    Kovac, J M; Leitch, E M; Pryke, C; Carlstrom, J E; Halverson, N W; Holzapfel, W L

    The past several years have seen the emergence of a standard cosmological model, in which small temperature differences in the cosmic microwave background (CMB) radiation on angular scales of the order of a degree are understood to arise from acoustic oscillations in the hot plasma of the early Universe, arising from primordial density fluctuations. Within the context of this model, recent measurements of the temperature fluctuations have led to profound conclusions about the origin, evolution and composition of the Universe. Using the measured temperature fluctuations, the theoretical framework predicts the level of polarization of the CMB with essentially no free parameters. Therefore, a measurement of the polarization is a critical test of the theory and thus of the validity of the cosmological parameters derived from the CMB measurements. Here we report the detection of polarization of the CMB with the Degree Angular Scale Interferometer (DASI). The polarization is deteced with high confidence, and its level and spatial distribution are in excellent agreement with the predictions of the standard theory. PMID:12490941

  4. Observing the Cosmic Microwave Background Radiation: A Unique Window on the Early Universe

    NASA Technical Reports Server (NTRS)

    Hinshaw, Gary; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics,of the early universe. Within the framework of inflationary dark matter models observations of the anisotropy on sub-degree angular scales will reveal the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of approx. 1100. The validity of inflationary models will be tested and, if agreement is found, accurate values for most of the key cosmological parameters will result. If disagreement is found, we will need to rethink our basic ideas about the physics of the early universe. I will present an overview of the physical processes at work in forming the anisotropy and discuss what we have already learned from current observations. I will conclude with a brief overview of the recently launched Microwave Anisotropy Probe (MAP) mission which will observe the anisotropy over the full sky with 0.21 degree angular resolution. At the time of this meeting, MAP will have just arrived at the L2 Lagrange point, marking the start of its observing campaign. The MAP hardware is being produced by Goddard in partnership with Princeton University.

  5. A guide to designing future ground-based cosmic microwave background experiments

    SciTech Connect

    Wu, W. L. K.; Kuo, C. L.; Errard, J.; Dvorkin, C.; Lee, A. T.; McDonald, P.; Zahn, O.; Slosar, A.

    2014-06-20

    In this follow-up work to the high energy physics Community Summer Study 2013 (aka SNOWMASS), we explore the scientific capabilities of a future Stage IV cosmic microwave background polarization experiment under various assumptions on detector count, resolution, and sky coverage. We use the Fisher matrix technique to calculate the expected uncertainties of cosmological parameters in νΛCDM that are especially relevant to the physics of fundamental interactions, including neutrino masses, effective number of relativistic species, dark energy equation of state, dark matter annihilation, and inflationary parameters. To further chart the landscape of future cosmology probes, we include forecasted results from the baryon acoustic oscillation signal as measured by Dark Energy Spectroscopic Instrument to constrain parameters that would benefit from low redshift information. We find the following best 1σ constraints: σ(M {sub ν}) = 15 meV, σ(N {sub eff}) = 0.0156, dark energy figure of merit = 303, σ(p {sub ann}) = 0.00588 × 3 × 10{sup –26} cm{sup 3} s{sup –1} GeV{sup –1}, σ(Ω {sub K}) = 0.00074, σ(n{sub s} ) = 0.00110, σ(α {sub s}) = 0.00145, and σ(r) = 0.00009. We also detail the dependencies of the parameter constraints on detector count, resolution, and sky coverage.

  6. The intrinsic B-mode polarisation of the Cosmic Microwave Background

    SciTech Connect

    Fidler, Christian; Pettinari, Guido W.; Crittenden, Robert; Koyama, Kazuya; Wands, David; Beneke, Martin E-mail: Guido.Pettinari@sussex.ac.uk E-mail: Kazuya.Koyama@port.ac.uk

    2014-07-01

    We estimate the B-polarisation induced in the Cosmic Microwave Background by the non-linear evolution of density perturbations. Using the second-order Boltzmann code SONG, our analysis incorporates, for the first time, all physical effects at recombination. We also include novel contributions from the redshift part of the Boltzmann equation and from the bolometric definition of the temperature in the presence of polarisation. The remaining line-of-sight terms (lensing and time-delay) have previously been studied and must be calculated non-perturbatively. The intrinsic B-mode polarisation is present independent of the initial conditions and might contaminate the signal from primordial gravitational waves. We find this contamination to be comparable to a primordial tensor-to-scalar ratio of r ≅ 10{sup −7} at the angular scale ℓ ≅ 100, where the primordial signal peaks, and r ≅ 5 × 10{sup −5} at ℓ ≅ 700, where the intrinsic signal peaks. Therefore, we conclude that the intrinsic B-polarisation from second-order effects is not likely to contaminate future searches of primordial gravitational waves.

  7. LACK OF ANGULAR CORRELATION AND ODD-PARITY PREFERENCE IN COSMIC MICROWAVE BACKGROUND DATA

    SciTech Connect

    Kim, Jaiseung; Naselsky, Pavel

    2011-10-01

    We have investigated the angular correlation in the recent cosmic microwave background data. In addition to the known large-angle correlation anomaly, we find the lack of correlation at small angles with high statistical significance. We have investigated various non-cosmological contamination as well as the Wilkinson Microwave Anisotropy Probe (WMAP) team's simulated data. However, we have not found a definite cause. In the angular power spectrum of WMAP data, there exists anomalous odd-parity preference at low multipoles. Noting the equivalence between the power spectrum and the correlation, we have investigated the association between the lack of large-angle correlation and the odd-parity preference. From our investigation, we find that the odd-parity preference at low multipoles is, in fact, a phenomenological origin of the lack of large-angle correlation. Further investigation is required to find out whether the origin of the anomaly is cosmological or due to unaccounted systematics. The data from the Planck surveyor, which has systematics distinct from WMAP, will greatly help us to resolve its origin.

  8. Maximum Likelihood Foreground Cleaning for Cosmic Microwave Background Polarimeters in the Presence of Systematic Effects

    NASA Astrophysics Data System (ADS)

    Bao, C.; Baccigalupi, C.; Gold, B.; Hanany, S.; Jaffe, A.; Stompor, R.

    2016-03-01

    We extend a general maximum likelihood foreground estimation for cosmic microwave background (CMB) polarization data to include estimation of instrumental systematic effects. We focus on two particular effects: frequency band measurement uncertainty and instrumentally induced frequency dependent polarization rotation. We assess the bias induced on the estimation of the B-mode polarization signal by these two systematic effects in the presence of instrumental noise and uncertainties in the polarization and spectral index of Galactic dust. Degeneracies between uncertainties in the band and polarization angle calibration measurements and in the dust spectral index and polarization increase the uncertainty in the extracted CMB B-mode power, and may give rise to a biased estimate. We provide a quantitative assessment of the potential bias and increased uncertainty in an example experimental configuration. For example, we find that with 10% polarized dust, a tensor to scalar ratio of r = 0.05, and the instrumental configuration of the E and B experiment balloon payload, the estimated CMB B-mode power spectrum is recovered without bias when the frequency band measurement has 5% uncertainty or less, and the polarization angle calibration has an uncertainty of up to 4°.

  9. A degree scale anisotropy measurement of the cosmic microwave background near the star Gamma Ursae Minoris

    NASA Technical Reports Server (NTRS)

    Gundersen, J. O.; Clapp, A. C.; Devlin, M.; Holmes, W.; Fischer, M. L.; Meinhold, P. R.; Lange, A. E.; Lubin, P. M.; Richards, P. L.; Smoot, G. F.

    1993-01-01

    Results from a search for anisotropy in the cosmic microwave background (CMB) are presented from the third flight of the Millimeter-wave Anisotropy experiment. The CMB observation occurred over 1.37 hours and covered a 6.24 sq deg area of the sky where very little foreground emission is expected. Significant correlated structure is observed at 6 and 9/cm. At 12/cm we place an upper limit on the structure. The relative amplitudes at 6, 9, and 12/cm are consistent with a CMB spectrum. The spectrum of the structure is inconsistent with thermal emission from known forms of interstellar dust. Synchrotron and free-free emission would both require unusually flat spectral indices at cm wavelengths in order to account for the amplitude of the observed structure. Although known systematic errors are not expected to contribute significantly to any of the three optical channels, excess sidelobe contamination cannot be definitively ruled out. If all the structure is attributed to CMB anisotropy, a value of the weighted rms of the 6 and 9/cm channels of Delta T/T(CMB) = 4.7 +/- 0.8 x 10 exp -5 (+/- 1 sigma) was measured. If the CMB anisotropy is assumed to have a Gaussian autocorrelation function with a coherence angle of 25 arcmin, then the most probable value is Delta T/T(CMB) = 4.2 +1.7 or -1.1 x 10 exp -5, where the +/- refers to the 95 percent confidence limits.

  10. The Atacama Cosmology Telescope: Cross-Correlation of Cosmic Microwave Background Lensing and Quasars

    NASA Technical Reports Server (NTRS)

    Sherwin, Blake D; Das, Sudeep; Haijian, Amir; Addison, Graeme; Bond, Richard; Crichton, Devin; Devlin, Mark J.; Dunkley, Joanna; Gralla, Megan B.; Halpern, Mark; Hill, J. Colin; Hincks, Adam D.; Hughes, John P.; Huffenberger, Kevin; Hlozek, Renee; Kosowsky, Arthur; Louis, Thibaut; Marriage, Tobias A.; Marsden, Danica; Menanteau, Felipe; Moodley, Kavilan; Niemack, Michael D.; Page, Lyman A.; Reese. Erik D.; Sehgal, Neelima; Sievers, Jon; Sifon, Cristobal; Spergel, David N.; Staggs, Suzanne T.; Switzer, Eric R.; Wollack, Ed.

    2012-01-01

    We measure the cross-correlation of Atacama cosmology telescope cosmic microwave background (CMB) lensing convergence maps with quasar maps made from the Sloan Digital Sky Survey DR8 SDSS-XDQSO photometric catalog. The CMB lensing quasar cross-power spectrum is detected for the first time at a significance of 3.8 sigma, which directly confirms that the quasar distribution traces the mass distribution at high redshifts z > 1. Our detection passes a number of null tests and systematic checks. Using this cross-power spectrum, we measure the amplitude of the linear quasar bias assuming a template for its redshift dependence, and find the amplitude to be consistent with an earlier measurement from clustering; at redshift z ap 1.4, the peak of the distribution of quasars in our maps, our measurement corresponds to a bias of b = 2.5 +/- 0.6. With the signal-to-noise ratio on CMB lensing measurements likely to improve by an order of magnitude over the next few years, our results demonstrate the potential of CMB lensing crosscorrelations to probe astrophysics at high redshifts.

  11. A measurement of the cosmic microwave background polarization with the south pole telescope

    NASA Astrophysics Data System (ADS)

    Crites, Abigail Tinney

    We present maps of the cosmic microwave background (CMB) polarization at 90 and 150 GHz measured with SPTpol and the first EE and TE CMB power spectrum measurements from SPTpol. We also describe the SPTpol instrument in detail. We discuss the development of the SPTpol camera including the cryogenic design and the transition edge sensor (TES) detectors developed at NIST and Argonne National Laboratory. The goals of the SPTpol project are to exploit the high resolution of the telescope (1 arcminute beam) and the high sensitivity afforded by the 1536 detector camera to measure the E-mode power spectrum of the CMB, characterize the B-mode polarization induced by the gravitational lensing of the primordial E-mode CMB polarization, and to detector set an upper limit on the level of the B-mode polarization from inflationary gravitational waves. This thesis is a first step toward accomplishing these goals. Measuring the E-mode power spectrum will allow us to improve constraints on parameters of the current cosmological models that are sensitive to the damping tail of the CMB.

  12. POLARBEAR2: A new multichroic receiver for precision measurements of cosmic microwave background polarization

    NASA Astrophysics Data System (ADS)

    Barron, Darcy; POLARBEAR Collaboration

    2014-01-01

    POLARBEAR-2 is a new receiver that will be installed in 2014 alongside the currently observing POLARBEAR-1 receiver, on a new telescope as a part of the Simons Array. The science goals of the POLARBEAR project are to do a deep search for B-mode polarization of the cosmic microwave background (CMB) created by inflationary gravitational waves, as well as characterize the CMB B-mode signal at smaller angular scales, where it originates from weak gravitational lensing. The Simons Array will include a total of three off-axis Gregorian telescopes with 3.5 m primary mirrors, located in the Chajnantor Astronomical Park in the Atacama Desert in Chile. Phased upgrades to receiver technology will enable us to improve sensitivity and capabilities, while continuing a deep survey of 80% of the sky. The POLARBEAR-2 receiver has a larger area focal plane with new dichroic pixels, with bands at 95 GHz and 150 GHz, and a total of 7,588 polarization sensitive antenna-coupled transition edge sensor bolometers. The focal plane is cooled to 250 milliKelvin, and the bolometers will be read-out by SQUID amplifiers with 32x frequency domain multiplexing. The focal plane is designed to have a noise equivalent temperature of 5.7 μK√s.

  13. Spectral-luminosity evolution of active galactic nuclei and the cosmic X- and gamma ray background

    NASA Technical Reports Server (NTRS)

    Leiter, Darryl; Boldt, Elihu

    1992-01-01

    Coherent electromagnetic dynamo acceleration processes, which act on charge particles within the context of black hole accretion disk scenarios, are generally regarded as the underlying central power source for active galactic nuclei (AGN). If the precursor active galaxies (PAG) for such AGN are formed at high redshift and contain initial seed black holes with mass approximately equal to 10(exp 4) solar masses, then the Eddington limited X-ray radiation emitted during their lifetime will undergo the phenomenon of 'spectral-luminosity evolution'. When accretion disks are first formed at the onset of galaxy formation the accretion rate occurs at very high values of luminosity/size compactness parameter L/R greater than 10(exp 30) erg/cm-sec. In the absence of extended structure, such high values of L/R generate dynamic constraints which suppress coherent, black hole/accretion disk dynamo particle acceleration processes. This inhibits nonthermal radiation processes and causes the spectrum of X-radiation emitted by PAG to be predominantly thermal. A superposition of PAG sources at z is greater than or equal to 6 can account for the residual cosmic X-ray background (CXB) obtained from the total CXB after subtraction of foreground AGN sources associated with present epoch Seyfert galaxies. The manner in which the PAG undergo spectral-luminosity evolution into Seyfert galaxies is investigated.

  14. The intrinsic B-mode polarisation of the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Fidler, Christian; Pettinari, Guido W.; Beneke, Martin; Crittenden, Robert; Koyama, Kazuya; Wands, David

    2014-07-01

    We estimate the B-polarisation induced in the Cosmic Microwave Background by the non-linear evolution of density perturbations. Using the second-order Boltzmann code SONG, our analysis incorporates, for the first time, all physical effects at recombination. We also include novel contributions from the redshift part of the Boltzmann equation and from the bolometric definition of the temperature in the presence of polarisation. The remaining line-of-sight terms (lensing and time-delay) have previously been studied and must be calculated non-perturbatively. The intrinsic B-mode polarisation is present independent of the initial conditions and might contaminate the signal from primordial gravitational waves. We find this contamination to be comparable to a primordial tensor-to-scalar ratio of r simeq 10-7 at the angular scale l simeq 100, where the primordial signal peaks, and r simeq 5 × 10-5 at l simeq 700, where the intrinsic signal peaks. Therefore, we conclude that the intrinsic B-polarisation from second-order effects is not likely to contaminate future searches of primordial gravitational waves.

  15. Design and Deployment of the Polarbear Cosmic Microwave Background Polarization Experiment

    NASA Astrophysics Data System (ADS)

    Arnold, Kam Stahly

    2010-12-01

    POLARBEAR is a Cosmic Microwave Background (CMB) polarization experiment that will measure the CMB polarization angular power spectrum with unprecedented precision, searching for evidence of inflationary gravitational waves and the gravitational lensing of the CMB polarization by large scale structure. This dissertation presents an overview of the design of the instrument, focusing on the design and fabrication of the focal plane, and presents the results of some tests of instrument performance, both in the laboratory and from the initial engineering deployment. The structure of this thesis is as follows: Chapter 1 introduces the theoretical constructs used to describe the CMB polarization anisotropies, and the state of measurements in the field. Chapter 2 gives an overview of the choices made in the instrument design. Chapter 3 discusses the fundamental limits to the sensitivity of bolometric detectors, and chapter 4 explains the design choices involved in populating the focal plane with detectors. Chapter 5 describes the details of the detector architecture and fabrication, and chapter 6 the details of selecting the spectral band of the detectors. Finally, chapter 7 goes through some results obtained before and during the POLARBEAR engineering run in 2010, and comments on the work to be done before the Chilean deployment.

  16. Antenna-coupled Superconducting Bolometers for Observations of the Cosmic Microwave Background Polarization

    NASA Astrophysics Data System (ADS)

    Myers, Michael James

    We describe the development of a novel millimeter-wave cryogenic detector. The device integrates a planar antenna, superconducting transmission line, bandpass filter, and bolometer onto a single silicon wafer. The bolometer uses a superconducting Transition-Edge Sensor (TES) thermistor, which provides substantial advantages over conventional semiconductor bolometers. The detector chip is fabricated using standard micro-fabrication techniques. This highly-integrated detector architecture is particularly well-suited for use in the de- velopment of polarization-sensitive cryogenic receivers with thousands of pixels. Such receivers are needed to meet the sensitivity requirements of next-generation cosmic microwave background polarization experiments. The design, fabrication, and testing of prototype array pixels are described. Preliminary considerations for a full array design are also discussed. A set of on-chip millimeter-wave test structures were developed to help understand the performance of our millimeter-wave microstrip circuits. These test structures produce a calibrated transmission measurement for an arbitrary two-port circuit using optical techniques, rather than a network analyzer. Some results of fabricated test structures are presented.

  17. Cosmic microwave background observations with the Jodrell Bank-IAC interferometer at 33GHz

    NASA Astrophysics Data System (ADS)

    Dicker, S. R.; Melhuish, S. J.; Davies, R. D.; Gutiérrez, C. M.; Rebolo, R.; Harrison, D. L.; Davis, R. J.; Wilkinson, A.; Hoyland, R. J.; Watson, R. A.

    1999-11-01

    This paper presents the first results obtained with the Jodrell Bank-IAC two-element 33-GHz interferometer. The instrument was designed to measure the level of the cosmic microwave background (CMB) fluctuations at angular scales of 1 deg-2 deg. The observations analysed here were taken in a strip of the sky at Dec.=+41 deg with an element separation of 16.7λ, which gives a maximum sensitivity to ~1.6° structures on the sky. The data processing and calibration of the instrument are described. The sensitivity achieved in each of the two channels is 7μK per resolution element. A reconstruction of the sky at Dec.=+41 deg using a maximum entropy method shows the presence of structure at a high level of significance. A likelihood analysis, assuming a flat CMB spatial power spectrum, gives a best estimate of the level of CMB fluctuations of ΔTl43-12+13μK for the range l=109+/-19 the main uncertainty in this result arises from sample variance. We consider that the contamination from the Galaxy is small. These results represent a new determination of the CMB power spectrum on angular scales at which previous results show a large scatter; our new results are in agreement with the theoretical predictions of the standard inflationary cold dark matter models.

  18. A Simple Test for Non-Gaussianity in Cosmic Microwave Background Radiation Measurements

    NASA Astrophysics Data System (ADS)

    Graham, Paul; Turok, Neil; Lubin, P. M.; Schuster, J. A.

    1995-08-01

    We propose a set of statistics for detecting non-Gaussianity in one-dimensional cosmic microwave background radiation (CMBR) anisotropy data sets. These statistics are both simple and, according to calculations over a space of linear combinations of three-point functions, nearly optimal at detecting certain types of nonGaussian features. We use this statistic to analyze the anisotropy detected by the UCSB SP91 experiment. According to this statistic the mean of the four frequency channels is significantly non-Gaussian. If this signal represents primordial CMBR fluctuations, it would be highly unlikely in a Gaussian theory with a small coherence angle, such as "standard" (n = 1,Ωb = 0.05, h = 0.5, Δ = 0) inflation. We cannot tell whether the observed non-Gaussian signal is cosmological in origin, but if we assume it due instead to foreground emission, and remove the points responsible for the non-Gaussian behavior, the rms of the remaining fluctuations is improbably low for the "standard" inflation theory. Further data are clearly needed before any definitive conclusions may be drawn. We also generalize the ideas behind this statistic to non-Gaussian features that might be detected in other experimental schemes.

  19. Imaging the inside of thick structures using cosmic rays

    NASA Astrophysics Data System (ADS)

    Guardincerri, E.; Durham, J. M.; Morris, C.; Bacon, J. D.; Daughton, T. M.; Fellows, S.; Morley, D. J.; Johnson, O. R.; Plaud-Ramos, K.; Poulson, D. C.; Wang, Z.

    2016-01-01

    The authors present here a new method to image reinforcement elements inside thick structures and the results of a demonstration measurement performed on a mock-up wall built at Los Alamos National Laboratory. The method, referred to as "multiple scattering muon radiography", relies on the use of cosmic-ray muons as probes. The work described in this article was performed to prove the viability of the technique as a means to image the interior of the dome of Florence Cathedral Santa Maria del Fiore, one of the UNESCO World Heritage sites and among the highest profile buildings in existence. Its result shows the effectiveness of the technique as a tool to radiograph thick structures and image denser object inside them.

  20. Measurement of the cosmic microwave background using BEAST for the determination of cosmological parameters

    NASA Astrophysics Data System (ADS)

    Childers, Jeffery Dale

    The Background Emission Anisotropy Scanning Telescope (BEAST) is a millimeter wavelength experiment designed to generate maps of fluctuations in the cosmic microwave background (CMB). The telescope is composed of an off-axis Gregorian optical system with a 2.2 meter primary that focuses the collected microwave radiation onto an array of cryogenically cooled high electron mobility transistor (HEMT) receivers. This array is composed of six corrugated scalar feed horns in the Q band (38 to 45 GHz) and two more in the Ka band (26 to 36 GHz) with one of the six Q-band horns connected to an ortho-mode transducer for extraction of both polarizations incident on the single feed. The system has a minimum beam size of 20' with an average sensitivity of 900 m K [Special characters omitted.] per receiver. A map of the CMB centered on the north celestial pole has been generated from the BEAST telescope in a 9 ° wide annulus at declination 37° with a typical pixel error of 57 ± 5 m K when smoothed to 30' resolution. Cosmological parameter estimation of the power spectrum resulting from the map provides a measure of O k == 1- O total = -0.0= 74 ± .070, which is consistent with a flat universe. This paper describes the design and performance of the BEAST instrument and provides the details of subsystems developed and used toward the goal of generating a map of CMB fluctuations on 20' scales with sensitivity in l space between l ~100 and l ~500. A summary of the map and results generated by an observing campaign at the University of California White Mountain Research Station are also included.

  1. Identification of galaxy clusters in cosmic microwave background maps using the Sunyaev-Zel'dovich effect

    NASA Astrophysics Data System (ADS)

    Novaes, C. P.; Wuensche, C. A.

    2012-09-01

    Context. The Planck satellite was launched in 2009 by the European Space Agency to study the properties of the cosmic microwave background (CMB). An expected result of the Planck data analysis is the distinction of the various contaminants of the CMB signal. Among these contaminants is the Sunyaev-Zel'dovich (SZ) effect, which is caused by the inverse Compton scattering of CMB photons by high energy electrons in the intracluster medium of galaxy clusters. Aims: We modify a public version of the JADE (Joint Approximate Diagonalization of Eigenmatrices) algorithm, to deal with noisy data, and then use this algorithm as a tool to search for SZ clusters in two simulated datasets. Methods: The first dataset is composed of simple "homemade" simulations and the second of full sky simulations of high angular resolution, available at the LAMBDA (Legacy Archive for Microwave Background Data Analysis) website. The process of component separation can be summarized in four main steps: (1) pre-processing based on wavelet analysis, which performs an initial cleaning (denoising) of data to minimize the noise level; (2) the separation of the components (emissions) by JADE; (3) the calibration of the recovered SZ map; and (4) the identification of the positions and intensities of the clusters using the SExtractor software. Results: The results show that our JADE-based algorithm is effective in identifying the position and intensity of the SZ clusters, with the purities being higher then 90% for the extracted "catalogues". This value changes slightly according to the characteristics of noise and the number of components included in the input maps. Conclusions: The main highlight of our developed work is the effective recovery rate of SZ sources from noisy data, with no a priori assumptions. This powerful algorithm can be easily implemented and become an interesting complementary option to the "matched filter" algorithm (hereafter MF) widely used in SZ data analysis.

  2. Detecting the Cosmic Microwave Background at the Frontier of Cosmology and in the Classroom

    NASA Astrophysics Data System (ADS)

    Kovac, John

    2012-02-01

    The 3K blackbody Cosmic Microwave Background (CMB), while exceedingly faint, is the most abundant light in the Universe, permeating all of space as a relic of the hot, dense, primordial fireball. Its detection in 1965 established the Big Bang as the standard model of cosmology and earned its co-discoverers Penzias and Wilson a Nobel Prize. Over the past two decades, advances in detector technology driven by CMB research have produced telescopes with ever-increasing numbers of photon background-limited microwave detectors, capable of mapping fine structure of the CMB to micro-Kelvin precision. These have had enormous impact, determining the geometry of the universe, quantifying the dark matter and dark energy that dominate it, and detecting the faint polarization arising from the primordial seeds of structure. The current frontier is defined by new arrays of thousands of superconducting, polarized detectors producing maps approaching nano-Kelvin precision. In this decade, these measurements will answer questions about the physics driving the earliest moments of the Big Bang and will survey the large-scale structure of the universe, determining neutrino masses and constraining the nature of dark energy. The advanced detector technology fueling this frontier provides superb device-physics training for graduate students and postdocs working on current-generation CMB telescopes. At the same time, careful experimental techniques developed for CMB observations can now be combined with inexpensive high-quality satellite TV detectors to allow even undergraduates to detect the CMB, reproducing Penzias and Wilson's famous discovery. I describe one such undergraduate class at Harvard, which builds CMB telescopes from scratch in a few weeks with a modest budget, teaching students about microwave techniques and detectors and allowing them to find their own evidence for the Big Bang.

  3. Evaluation of the cosmic-ray induced background in coded aperture high energy gamma-ray telescopes

    NASA Technical Reports Server (NTRS)

    Owens, Alan; Barbier, Loius M.; Frye, Glenn M.; Jenkins, Thomas L.

    1991-01-01

    While the application of coded-aperture techniques to high-energy gamma-ray astronomy offers potential arc-second angular resolution, concerns were raised about the level of secondary radiation produced in a thick high-z mask. A series of Monte-Carlo calculations are conducted to evaluate and quantify the cosmic-ray induced neutral particle background produced in a coded-aperture mask. It is shown that this component may be neglected, being at least a factor of 50 lower in intensity than the cosmic diffuse gamma-rays.

  4. Cosmological backgrounds of gravitational waves and eLISA/NGO: phase transitions, cosmic strings and other sources

    SciTech Connect

    Binétruy, Pierre; Dufaux, Jean-François; Caprini, Chiara E-mail: bohe@iap.fr E-mail: dufaux@apc.univ-paris7.fr

    2012-06-01

    We review several cosmological backgrounds of gravitational waves accessible to direct-detection experiments, with a special emphasis on those backgrounds due to first-order phase transitions and networks of cosmic (super-)strings. For these two particular sources, we revisit in detail the computation of the gravitational wave background and improve the results of previous works in the literature. We apply our results to identify the scientific potential of the NGO/eLISA mission of ESA regarding the detectability of cosmological backgrounds.

  5. Signatures of anisotropic sources in the squeezed-limit bispectrum of the cosmic microwave background

    SciTech Connect

    Shiraishi, Maresuke; Komatsu, Eiichiro; Peloso, Marco; Barnaby, Neil E-mail: komatsu@mpa-garching.mpg.de E-mail: barnaby@physics.umn.edu

    2013-05-01

    The bispectrum of primordial curvature perturbations in the squeezed configuration, in which one wavenumber, k{sub 3}, is much smaller than the other two, k{sub 3} << k{sub 1} ≈ k{sub 2}, plays a special role in constraining the physics of inflation. In this paper we study a new phenomenological signature in the squeezed-limit bispectrum: namely, the amplitude of the squeezed-limit bispectrum depends on an angle between k{sub 1} and k{sub 3} such that B{sub ζ}(k{sub 1},k{sub 2},k{sub 3}) → 2Σ{sub L}c{sub L}P{sub L}( k-circumflex {sub 1}· k-circumflex {sub 3})P{sub ζ}(k{sub 1})P{sub ζ}(k{sub 3}), where P{sub L} are the Legendre polynomials. While c{sub 0} is related to the usual local-form f{sub NL} parameter as c{sub 0} = 6f{sub NL}/5, the higher-multipole coefficients, c{sub 1}, c{sub 2}, etc., have not been constrained by the data. Primordial curvature perturbations sourced by large-scale magnetic fields generate non-vanishing c{sub 0}, c{sub 1}, and c{sub 2}. Inflation models whose action contains a term like I(φ){sup 2}F{sup 2} generate c{sub 2} = c{sub 0}/2. A recently proposed ''solid inflation'' model generates c{sub 2} >> c{sub 0}. A cosmic-variance-limited experiment measuring temperature anisotropy of the cosmic microwave background up to l{sub max} = 2000 is able to measure these coefficients down to δc{sub 0} = 4.4, δc{sub 1} = 61, and δc{sub 2} = 13 (68% CL). We also find that c{sub 0} and c{sub 1}, and c{sub 0} and c{sub 2}, are nearly uncorrelated. Measurements of these coefficients will open up a new window into the physics of inflation such as the existence of vector fields during inflation or non-trivial symmetry structure of inflaton fields. Finally, we show that the original form of the Suyama-Yamaguchi inequality does not apply to the case involving higher-spin fields, but a generalized form does.

  6. Primordial Gravitational Wave Detectability with Deep Small-sky Cosmic Microwave Background Experiments

    NASA Astrophysics Data System (ADS)

    Farhang, M.; Bond, J. R.; Doré, O.; Netterfield, C. B.

    2013-07-01

    We use the Bayesian estimation on direct T - Q - U cosmic microwave background (CMB) polarization maps to forecast errors on the tensor-to-scalar power ratio r, and hence on primordial gravitational waves, as a function of sky coverage f sky. This map-based likelihood filters the information in the pixel-pixel space into the optimal combinations needed for r detection for cut skies, providing enhanced information over a first-step linear separation into a combination of E, B, and mixed modes, and ignoring the latter. With current computational power and for typical resolutions appropriate for r detection, the large matrix inversions required are accurate and fast. Our simulations explore two classes of experiments, with differing bolometric detector numbers, sensitivities, and observational strategies. One is motivated by a long duration balloon experiment like Spider, with pixel noise \\propto \\sqrt{f_{sky}} for a specified observing period. This analysis also applies to ground-based array experiments. We find that, in the absence of systematic effects and foregrounds, an experiment with Spider-like noise concentrating on f sky ~ 0.02-0.2 could place a 2σ r ≈ 0.014 boundary (~95% confidence level), which rises to 0.02 with an l-dependent foreground residual left over from an assumed efficient component separation. We contrast this with a Planck-like fixed instrumental noise as f sky varies, which gives a Galaxy-masked (f sky = 0.75) 2σ r ≈ 0.015, rising to ≈0.05 with the foreground residuals. Using as the figure of merit the (marginalized) one-dimensional Shannon entropy of r, taken relative to the first 2003 WMAP CMB-only constraint, gives -2.7 bits from the 2012 WMAP9+ACT+SPT+LSS data, and forecasts of -6 bits from Spider (+ Planck); this compares with up to -11 bits for CMBPol, COrE, and PIXIE post-Planck satellites and -13 bits for a perfectly noiseless cosmic variance limited experiment. We thus confirm the wisdom of the current strategy for r

  7. PRIMORDIAL GRAVITATIONAL WAVE DETECTABILITY WITH DEEP SMALL-SKY COSMIC MICROWAVE BACKGROUND EXPERIMENTS

    SciTech Connect

    Farhang, M.; Bond, J. R.; Netterfield, C. B.; Dore, O.

    2013-07-01

    We use the Bayesian estimation on direct T - Q - U cosmic microwave background (CMB) polarization maps to forecast errors on the tensor-to-scalar power ratio r, and hence on primordial gravitational waves, as a function of sky coverage f{sub sky}. This map-based likelihood filters the information in the pixel-pixel space into the optimal combinations needed for r detection for cut skies, providing enhanced information over a first-step linear separation into a combination of E, B, and mixed modes, and ignoring the latter. With current computational power and for typical resolutions appropriate for r detection, the large matrix inversions required are accurate and fast. Our simulations explore two classes of experiments, with differing bolometric detector numbers, sensitivities, and observational strategies. One is motivated by a long duration balloon experiment like Spider, with pixel noise {proportional_to}{radical}(f{sub sky}) for a specified observing period. This analysis also applies to ground-based array experiments. We find that, in the absence of systematic effects and foregrounds, an experiment with Spider-like noise concentrating on f{sub sky} {approx} 0.02-0.2 could place a 2{sigma}{sub r} Almost-Equal-To 0.014 boundary ({approx}95% confidence level), which rises to 0.02 with an l-dependent foreground residual left over from an assumed efficient component separation. We contrast this with a Planck-like fixed instrumental noise as f{sub sky} varies, which gives a Galaxy-masked (f{sub sky} = 0.75) 2{sigma}{sub r} Almost-Equal-To 0.015, rising to Almost-Equal-To 0.05 with the foreground residuals. Using as the figure of merit the (marginalized) one-dimensional Shannon entropy of r, taken relative to the first 2003 WMAP CMB-only constraint, gives -2.7 bits from the 2012 WMAP9+ACT+SPT+LSS data, and forecasts of -6 bits from Spider (+ Planck); this compares with up to -11 bits for CMBPol, COrE, and PIXIE post-Planck satellites and -13 bits for a perfectly

  8. Probing the neutrino mass hierarchy with cosmic microwave background weak lensing

    NASA Astrophysics Data System (ADS)

    Hall, Alex C.; Challinor, Anthony

    2012-09-01

    We forecast constraints on cosmological parameters with primary cosmic microwave background (CMB) anisotropy information and weak lensing reconstruction with a future post-Planck CMB experiment, the Cosmic Origins Explorer (COrE), using oscillation data on the neutrino mass splittings as prior information. Our Markov chain Monte Carlo (MCMC) simulations in flat models with a non-evolving equation of state of dark energy w give typical 68 per cent upper bounds on the total neutrino mass of 0.136 and 0.098 eV for the inverted and normal hierarchies, respectively, assuming the total summed mass is close to the minimum allowed by the oscillation data for the respective hierarchies (0.10 and 0.06 eV). Including geometric information from future baryon acoustic oscillation measurements with the complete Baryon Oscillation Spectroscopic Survey, Type Ia supernovae distance moduli from Wide-Field Infrared Survey Telescope (WFIRST) and a realistic prior on the Hubble constant, these upper limits shrink to 0.118 and 0.080 eV for the inverted and normal hierarchies, respectively. Addition of these distance priors also yields per cent-level constraints on w. We find tension between our MCMC results and the results of a Fisher matrix analysis, most likely due to a strong geometric degeneracy between the total neutrino mass, the Hubble constant and w in the unlensed CMB power spectra. If the minimal-mass, normal hierarchy were realized in nature, the inverted hierarchy should be disfavoured by the full data combination at typically greater than the 2σ level. For the minimal-mass inverted hierarchy, we compute the Bayes factor between the two hierarchies for various combinations of our forecast data sets, and find that the future cosmological probes considered here should be able to provide 'strong' evidence (odds ratio 12:1) for the inverted hierarchy. Finally, we consider potential biases of the other cosmological parameters from assuming the wrong hierarchy and find that all

  9. Signatures of anisotropic sources in the trispectrum of the cosmic microwave background

    SciTech Connect

    Shiraishi, Maresuke; Komatsu, Eiichiro; Peloso, Marco E-mail: komatsu@mpa-garching.mpg.de

    2014-04-01

    Soft limits of N-point correlation functions, in which one wavenumber is much smaller than the others, play a special role in constraining the physics of inflation. Anisotropic sources such as a vector field during inflation generate distinct angular dependence in all these correlators, and introduce a fix privileged direction in our sky. In this paper we focus on the four-point correlator (the trispectrum T). We adopt a parametrization motivated by models in which the inflaton φ is coupled to a vector field through a I{sup 2}(φ)F{sup 2} interaction, namely T{sub ζ}(k{sub 1},k{sub 2},k{sub 3},k{sub 4})≡∑{sub n}d{sub n}[P{sub n}( k-circumflex {sub 1}⋅ k-circumflex {sub 3})+P{sub n}( k-circumflex {sub 1}⋅ k-circumflex {sub 12})+P{sub n}( k-circumflex {sub 3}⋅ k-circumflex {sub 12})]P{sub ζ}(k{sub 1})P{sub ζ}(k{sub 3})P{sub ζ}(k{sub 12})+(23perm), where P{sub n} denotes the Legendre polynomials. This shape is enhanced when the wavenumbers of the diagonals of the quadrilateral are much smaller than the sides, k{sub i}. The coefficient of the isotropic part, d{sub 0}, is equal to τ{sub NL}/6 discussed in the literature. A I{sup 2}(φ)F{sup 2} interaction generates d{sub 2} = 2d{sub 0} which is, in turn, related to the quadrupole modulation parameter of the power spectrum, g{sub *}, as d{sub 2} ≈ 14|g{sub *}|N{sup 2} with N ≈ 60. We show that d{sub 0} and d{sub 2} can be equally well-constrained: the expected 68% CL error bars on these coefficients from a cosmic-variance-limited experiment measuring temperature anisotropy of the cosmic microwave background up to ℓ{sub max} = 2000 are δd{sub 2} ≈ 4δd{sub 0} = 105. Therefore, we can reach |g{sub *}| = 10{sup −3} by measuring the angle-dependent trispectrum. The current upper limit on τ{sub NL} from the Planck temperature maps yields |g{sub *}| < 0.02 (95% CL)

  10. A Hydrodynamic Approach to Cosmology: Nonlinear Effects on Cosmic Backgrounds in the Cold Dark Matter Model

    NASA Astrophysics Data System (ADS)

    Scaramella, Roberto; Cen, Renyue; Ostriker, Jeremiah P.

    1993-10-01

    Using the CDM model as a testbed, we produce and analyze sky maps of fluctuations in the cosmic background radiation field due to Sunyaev-Zel'dovich effect, as well as those seen in X-ray background at 1 keV and at 2 keV. These effects are due to the shock heating of baryons in the nonlinear phases of cosmic collapses. Comparing observations with computations provides a powerful tool to constrain cosmological models. We use a highly developed Eulerian mesh code with 1283 cells and 2 × 106 particles. Most of our information comes from simulations with box size 64 h-1 Mpc, but other calculations were made with L = 16 h-1 and L = 4 h-1 Mpc. A standard CDM input spectrum was used with amplitude defined by the requirement (ΔM/M)rms = 1/1.5 on 8 h-1 Mpc scales (lower than the COBE normalization by a factor of 1.6±0.4), with H0 = 50 km s-1 Mpc-1 and Ωb = 0.05. For statistical validity a large number of independent simulations must be run. In all, over 60 simulations were run from z = 20 to z = 0. We produce maps of 50' x 50' with 1' effective resolution by randomly stacking along the past light cone for 0.02 ≤ z ≤ 10 appropriate combinations of computational boxes of different comoving lengths, which are picked from among different realizations of initial conditions. We also compute time evolution, present intensity pixel distributions, and the autocorrelation function of sky fluctuations as a function of angular scale. Our most reliable results are obtained after deletion of bright sources having 1 keV intensity greater than 0.1 keV cm-2 sr-1 s-1 keV-1. Then for the Sunyaev-Zel'dovich parameter γ the mean and dispersion are [barγ, σ(γ)] = (4, 3) × 10-7 with a lognormal distribution providing a good fit for values of y greater than average. The angular correlation function (less secure) is roughly exponential with scale length ˜2'.5. For the X-ray intensity fluctuations, in units of keV s-1 sr-1 cm-2 keV-1 we find barIX1, X2 = (0.02, 0.006) and σX1, X2 = (0

  11. VizieR Online Data Catalog: The cosmic TeV gamma-ray background spectrum (Inoue+, 2016)

    NASA Astrophysics Data System (ADS)

    Inoue, Y.; Tanaka, Y. T.

    2016-05-01

    We select 35 known extragalactic TeV sources which are located at Galactic latitude |b|>=10° and whose low activity state flux is available, since our aim is to give conservative constraints on the total cosmic gamma-ray background (CGB) in the TeV band. For each source, we select the lowest fluxes among several TeV measurements by modern imaging atmospheric Cherenkov telescopes (IACTs; H.E.S.S., MAGIC, and VERITAS) and further restrict samples showing no significant variability in the TeV band during observations. The sample contains 30 blazars, 3 radio galaxies, and 2 starburst galaxies from the default TeVcat catalog (Wakely & Horan 2008ICRC....3.1341W) which include published sources only. We also include the Fermi third source (3FGL) catalog data (Acero et al. 2015, J/ApJS/218/23) to cover GeV gamma-ray spectra. The 3FGL catalog is based on its first 48 months of survey data. All of our sample have counterparts in the 3FGL catalog. (2 data files).

  12. Historical document image segmentation using background light intensity normalization

    NASA Astrophysics Data System (ADS)

    Shi, Zhixin; Govindaraju, Venu

    2004-12-01

    This paper presents a new document binarization algorithm for camera images of historical documents, which are especially found in The Library of Congress of the United States. The algorithm uses a background light intensity normalization algorithm to enhance an image before a local adaptive binarization algorithm is applied. The image normalization algorithm uses an adaptive linear or non-linear function to approximate the uneven background of the image due to the uneven surface of the document paper, aged color or uneven light source of the cameras for image lifting. Our algorithm adaptively captures the background of a document image with a "best fit" approximation. The document image is then normalized with respect to the approximation before a thresholding algorithm is applied. The technique works for both gray scale and color historical handwritten document images with significant improvement in readability for both human and OCR.

  13. Historical document image segmentation using background light intensity normalization

    NASA Astrophysics Data System (ADS)

    Shi, Zhixin; Govindaraju, Venu

    2005-01-01

    This paper presents a new document binarization algorithm for camera images of historical documents, which are especially found in The Library of Congress of the United States. The algorithm uses a background light intensity normalization algorithm to enhance an image before a local adaptive binarization algorithm is applied. The image normalization algorithm uses an adaptive linear or non-linear function to approximate the uneven background of the image due to the uneven surface of the document paper, aged color or uneven light source of the cameras for image lifting. Our algorithm adaptively captures the background of a document image with a "best fit" approximation. The document image is then normalized with respect to the approximation before a thresholding algorithm is applied. The technique works for both gray scale and color historical handwritten document images with significant improvement in readability for both human and OCR.

  14. Precise measurement of the cosmic microwave background temperature from optical observations of interstellar CN

    SciTech Connect

    Meyer, D.M.; Jura, M.

    1985-10-01

    We present very precise (S/N > 2000) observations of the 3874 A band of interstellar CN toward zeta Per and o Per. In the zeta Oph, zeta Per, and o Per lines of sight, the saturation-corrected CN line strengths yield respective excitation temperatures of 2.72 +- 0.05 K, 2.76 +- 0.05 K, and 2.78 +- 0.07 K for the J = 0--1 rotational transition at 2.64 mm. The excellent agreement among these temperatures confirms the expectation that the cosmic microwave background radiation (CMB) is primarily responsible for populating the excited rotational levels of interstellar CN. With small corrections for the local CN excitation due to electron impact, the J = 0--1 excitation temperatures toward zeta Oph, zeta Per, and o Per are all consistent with a CMB brightness temperature of 2.70 +- 0.04 K at 2.64 mm. This value represents the most precise determination to date of the CMB intensity at any wavelength. In addition, the CN J = 1--2 excitation temperatures toward these objects indicate a CMB temperature of 2.76 +- 0.20 K at 1.32 mm. Our temperatures at 2.64 mm and 1.32 mm are thus consistent with a 2.7 K blackbody spectrum for the CMB and do not support the spectral distortions observed near these wavelengths by Woody and Richards. Indeed, by confirming the blackbody character of the CMB spectrum at wavelengths near the peak of its flux, we have reinforced the simplest explanation of the CMB as primeval fireball radiation from a hot big bang.

  15. Foreground Cleaning for Cosmic Microwave Background Polarimeters in the Presence of Instrumental Effects

    NASA Astrophysics Data System (ADS)

    Bao, Chaoyun

    The Cosmic Microwave Background (CMB) B-mode polarization signal offers a direct probe of inflation, a period of exponential expansion in the extreme early universe. The inflationary CMB B-mode polarization signal, however, is subject to the contamination of polarized galactic thermal dust foreground emission. A robust foreground cleaning method is essential for CMB polarimeters targeting the inflationary B-mode signal. In this thesis I present my work on developing foreground cleaning algorithms particularly in the presence of instrumental effects. One of the instrumental effects I focus on in this work is the frequency dependent polarization rotation effect such as the one caused by an achromatic half-wave plate (AHWP). As an example, I use the AHWP of the E and B Experiment (EBEX) in this work and study the relation between the frequency dependent rotation effect and the characteristic parameters of the AHWP. To address the effect of an AHWP while removing galactic dust foreground contamination, I developed two foreground cleaning algorithms: a simple method that assumes perfect knowledge of the AHWP and a few simplifying assumptions, and a more sophisticated algorithm based on maximum likelihood method. Based on simulation results, the maximum likelihood foreground cleaning algorithm can recover CMB B-mode signal without any bias in the presence of band shape uncertainty, frequency dependent rotation effect and instrumental noise with realistic measurement accuracy of instrumental parameters. In this thesis I also present my work on calculating the atmospheric loading in the millimeter wave regime for sub-orbital CMB experiments such as EBEX. Having a proper prediction of the atmospheric loading is an important input to detector designs for CMB experiments.

  16. Degree-scale cosmic microwave background polarization measurements from three years of BICEP1 data

    SciTech Connect

    Barkats, D.; Aikin, R.; Bock, J. J.; Filippini, J.; Hristov, V. V.; Bischoff, C.; Buder, I.; Kovac, J. M.; Kaufman, J. P.; Keating, B. G.; Bierman, E. M.; Su, M.; Ade, P. A. R.; Battle, J. O.; Dowell, C. D.; Chiang, H. C.; Duband, L.; Hivon, E. F.; Holzapfel, W. L.; Jones, W. C.; and others

    2014-03-10

    BICEP1 is a millimeter-wavelength telescope designed specifically to measure the inflationary B-mode polarization of the cosmic microwave background at degree angular scales. We present results from an analysis of the data acquired during three seasons of observations at the South Pole (2006-2008). This work extends the two-year result published in Chiang et al., with additional data from the third season and relaxed detector-selection criteria. This analysis also introduces a more comprehensive estimation of band power window functions, improved likelihood estimation methods, and a new technique for deprojecting monopole temperature-to-polarization leakage that reduces this class of systematic uncertainty to a negligible level. We present maps of temperature, E- and B-mode polarization, and their associated angular power spectra. The improvement in the map noise level and polarization spectra error bars are consistent with the 52% increase in integration time relative to Chiang et al. We confirm both self-consistency of the polarization data and consistency with the two-year results. We measure the angular power spectra at 21 ≤ ℓ ≤ 335 and find that the EE spectrum is consistent with Lambda cold dark matter cosmology, with the first acoustic peak of the EE spectrum now detected at 15σ. The BB spectrum remains consistent with zero. From B-modes only, we constrain the tensor-to-scalar ratio to r=0.03{sub −0.23}{sup +0.27}, or r < 0.70 at 95% confidence level.

  17. Mildly obscured active galaxies and the cosmic X-ray background

    NASA Astrophysics Data System (ADS)

    Esposito, V.; Walter, R.

    2016-05-01

    Context. The diffuse cosmic X-ray background (CXB) is the sum of the emission of discrete sources, mostly massive black-holes accreting matter in active galactic nuclei (AGN). The CXB spectrum differs from the integration of the spectra of individual sources, calling for a large population, undetected so far, of strongly obscured Compton-thick AGN. Such objects are predicted by unified models, which attribute most of the AGN diversity to their inclination on the line of sight, and play an important role for the understanding of the growth of black holes in the early Universe. Aims: The percentage of strongly obscured Compton-thick AGN at low redshift can be derived from the observed CXB spectrum, if we assume AGN spectral templates and luminosity functions. Methods: We show that high signal-to-noise stacked hard X-ray spectra, derived from more than a billion seconds of effective exposure time with the Swift/BAT instrument, imply that mildly obscured Compton-thin AGN feature a strong reflection and contribute massively to the CXB. Results: A population of Compton-thick AGN larger than that which is effectively detected is not required to reproduce the CXB spectrum, since no more than 6% of the CXB flux can be attributed to them. The stronger reflection observed in mildly obscured AGN suggests that the covering factor of the gas and dust surrounding their central engines is a key factor in shaping their appearance. These mildly obscured AGN are easier to study at high redshift than Compton-thick sources are.

  18. Reconstructing Emission from Pre-reionization Sources with Cosmic Infrared Background Fluctuation Measurements by the JWST

    NASA Astrophysics Data System (ADS)

    Kashlinsky, A.; Mather, J. C.; Helgason, K.; Arendt, R. G.; Bromm, V.; Moseley, S. H.

    2015-05-01

    We present new methodology to use cosmic infrared background (CIB) fluctuations to probe sources at 10≲ z≲ 30 from a James Webb Space Telescope (JWST)/NIRCam configuration that will isolate known galaxies to 28 AB mag at 0.5-5 μm. At present significant mutually consistent source-subtracted CIB fluctuations have been identified in the Spitzer and AKARI data at ˜2-5 μm, but we demonstrate internal inconsistencies at shorter wavelengths in the recent CIBER data. We evaluate CIB contributions from remaining galaxies and show that the bulk of the high-z sources will be in the confusion noise of the NIRCam beam, requiring CIB studies. The accurate measurement of the angular spectrum of the fluctuations and probing the dependence of its clustering component on the remaining shot noise power would discriminate between the various currently proposed models for their origin and probe the flux distribution of its sources. We show that the contribution to CIB fluctuations from remaining galaxies is large at visible wavelengths for the current instruments precluding probing the putative Lyman-break of the CIB fluctuations. We demonstrate that with the proposed JWST configuration such measurements will enable probing the Lyman-break. We develop a Lyman-break tomography method to use the NIRCam wavelength coverage to identify or constrain, via the adjacent two-band subtraction, the history of emissions over 10≲ z≲ 30 as the universe comes out of the “Dark Ages.” We apply the proposed tomography to the current Spitzer/IRAC measurements at 3.6 and 4.5 μm, to find that it already leads to interestingly low upper limit on emissions at z≳ 30.

  19. Neural networks and the separation of cosmic microwave background and astrophysical signals in sky maps

    NASA Astrophysics Data System (ADS)

    Baccigalupi, C.; Bedini, L.; Burigana, C.; De Zotti, G.; Farusi, A.; Maino, D.; Maris, M.; Perrotta, F.; Salerno, E.; Toffolatti, L.; Tonazzini, A.

    2000-11-01

    We implement an independent component analysis (ICA) algorithm to separate signals of different origin in sky maps at several frequencies. Owing to its self-organizing capability, it works without prior assumptions on either the frequency dependence or the angular power spectrum of the various signals; rather, it learns directly from the input data how to identify the statistically independent components, on the assumption that all but, at most, one of the components have non-Gaussian distributions. We have applied the ICA algorithm to simulated patches of the sky at the four frequencies (30, 44, 70 and 100GHz) used by the Low Frequency Instrument of the European Space Agency's Planck satellite. Simulations include the cosmic microwave background (CMB), the synchrotron and thermal dust emissions, and extragalactic radio sources. The effects of the angular response functions of the detectors and of instrumental noise have been ignored in this first exploratory study. The ICA algorithm reconstructs the spatial distribution of each component with rms errors of about 1per cent for the CMB, and 10per cent for the much weaker Galactic components. Radio sources are almost completely recovered down to a flux limit corresponding to ~=0.7σCMB, where σCMB is the rms level of the CMB fluctuations. The signal recovered has equal quality on all scales larger than the pixel size. In addition, we show that for the strongest components (CMB and radio sources) the frequency scaling is recovered with per cent precision. Thus, algorithms of the type presented here appear to be very promising tools for component separation. On the other hand, we have been dealing here with a highly idealized situation. Work to include instrumental noise, the effect of different resolving powers at different frequencies and a more complete and realistic characterization of astrophysical foregrounds is in progress.

  20. MEASURING THE REDSHIFT DEPENDENCE OF THE COSMIC MICROWAVE BACKGROUND MONOPOLE TEMPERATURE WITH PLANCK DATA

    SciTech Connect

    De Martino, I.; Atrio-Barandela, F.; Da Silva, A.; Martins, C. J. A. P.; Kashlinsky, A.; Kocevski, D. E-mail: atrio@usal.es E-mail: Carlos.Martins@astro.up.pt E-mail: alexander.kashlinsky@nasa.gov

    2012-10-01

    We study the capability of Planck data to constrain deviations of the cosmic microwave background (CMB) blackbody temperature from adiabatic evolution using the thermal Sunyaev-Zeldovich anisotropy induced by clusters of galaxies. We consider two types of data sets depending on how the cosmological signal is removed: using a CMB template or using the 217 GHz map. We apply two different statistical estimators, based on the ratio of temperature anisotropies at two different frequencies and on a fit to the spectral variation of the cluster signal with frequency. The ratio method is biased if CMB residuals with amplitude {approx}1 {mu}K or larger are present in the data, while residuals are not so critical for the fit method. To test for systematics, we construct a template from clusters drawn from a hydro-simulation included in the pre-launch Planck Sky Model. We demonstrate that, using a proprietary catalog of X-ray-selected clusters with measured redshifts, electron densities, and X-ray temperatures, we can constrain deviations of adiabatic evolution, measured by the parameter {alpha} in the redshift scaling T(z) = T{sub 0}(1 + z){sup 1-{alpha}}, with an accuracy of {sigma}{sub {alpha}} = 0.011 in the most optimal case and with {sigma}{sub {alpha}} = 0.018 for a less optimal case. These results represent a factor of 2-3 improvement over similar measurements carried out using quasar spectral lines and a factor 6-20 with respect to earlier results using smaller cluster samples.