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Sample records for cosmic background explorer

  1. 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)

  2. 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)

  3. 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.

  4. 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.

  5. The Cosmic Background Explorer Satellite

    NASA Technical Reports Server (NTRS)

    Mather, J.; Kelsall, T.

    1980-01-01

    The Cosmic Background Explorer (COBE) satellite, planned for launch in 1985, will measure the diffuse infrared and microwave radiation of the universe over the entire wavelength range from a few microns to 1.3 cm. It will include three instruments: a set of microwave isotropy radiometers at 23, 31, 53, and 90 GHz, an interferometer spectrometer from 1 to 100/cm, and a filter photometer from 1 to 300 microns. The COBE satellite is designed to reach the sensitivity limits set by foreground sources such as the interstellar and interplanetary dust, starlight, and galactic synchrotron radiation, so that a diffuse residual radiation may be interpreted unambiguously as extragalactic

  6. The Cosmic Background Explorer /COBE/

    NASA Technical Reports Server (NTRS)

    Mather, J. C.

    1982-01-01

    The Cosmic Background Explorer (COBE) satellite, under study by NASA since 1976, will map the spectrum and the angular distribution of diffuse radiation from the universe over the entire wavelength range from 1 micron to 1.3 cm. It carries three instruments: a set of differential microwave radiometers (DMR) at 23.5, 31.4, 53, and 90GHz, a far infrared absolute spectrophotometer (FIRAS) covering 1 to 100 per cm, and a diffuse infrared background experiment (DIRBE) covering 1 to 300 microns. They will use the ideal space environment, a one year lifetime, and standard instrument techniques to achieve orders of magnitude improvements in sensitivity and accuracy, providing a fundamental data base for cosmology. The instruments are united by common purpose as well as similar environmental and orbital requirements. The data from all three experiments will be analyzed together, to distinguish nearby sources of radiation from the cosmologically interesting diffuse background radiations. Construction is planned to begin in 1982 for a launch in 1988.

  7. 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).

  8. 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.

  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. 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.

  11. 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.

  12. 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.; Gulkis, S.; Isaacman, R. B.; Janssen, M.

    1990-01-01

    The Cosmic Background Explorer, launched 18 Nov. 1989, has nearly completed its first full mapping of the sky with all three of its instruments: A Far Infrared Absolute Spectrometer (FIRAS) covering 0.1 to 10 mm, a set of Differential Microwave Radiometers (DMR) operating at 3.3, 5.7, and 9.6 mm, and a diffuse Infrared Background Experiment (DIRBE) spanning 1 to 300 microns in ten bands. A preliminary map of the sky derived from DIRBE data is presented. Initial cosmological implications include: a limit on the comptonization parameter of 0.001, on the chemical potential parameter of 0.01, a strong limit on the existence of a hot smooth intergalactic medium, and a confirmation that the dipole anisotropy has the spectrum expected from a Doppler shift of a blackbody. There are no significant anisotropies in the microwave sky detected, other than from our own galaxy and a cos theta dipole anisotropy whose amplitude and direction agree with previous data. At shorter wavelengths, the sky spectrum and anisotropies are dominated by emission from local sources of emission within our Galaxy and Solar System. Preliminary comparison of IRAS (Infrared Astronomical Satellite) and DRIBE sky brightnesses toward the ecliptic poles shows the IRAS values to be significantly higher than found by DRIBE at 100 microns. The presence of gain and zero point errors in the IRAS total brightness data is suggested. The spacecraft, instrument designs, and data reduction methods are described.

  13. 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.

  14. 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.

  15. 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.

  16. The cryo-testing of infrared filters and beamsplitters for the cosmic background explorer's instruments

    NASA Technical Reports Server (NTRS)

    Heaney, James B.; Stewart, Kenneth P.; Boucarut, Rene A.; Alley, Phillip W.; Korb, Andrew R.

    1986-01-01

    The cryooptical methods used to measure the spectral transmittances of filters and beamsplitters for the Cosmic Background Explorer's instruments are described. Measured results demonstrate the temperature sensitivity, or insensitivity, of various infrared filter designs within the wavelength range from 1 to 1000 microns.

  17. The cryo-testing of infrared filters and beamsplitters for the cosmic background explorer's instruments

    NASA Technical Reports Server (NTRS)

    Heaney, James B.; Stewart, Kenneth P.; Boucarut, Rene A.; Alley, Phillip W.; Korb, Andrew R.

    1986-01-01

    The cryooptical methods used to measure the spectral transmittances of filters and beamsplitters for the Cosmic Background Explorer's instruments are described. Measured results demonstrate the temperature sensitivity, or insensitivity, of various infrared filter designs within the wavelength range from 1 to 1000 microns.

  18. 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.

  19. Cosmic microwave background theory.

    PubMed

    Bond, J R

    1998-01-06

    A long-standing goal of theorists has been to constrain cosmological parameters that define the structure formation theory from cosmic microwave background (CMB) anisotropy experiments and large-scale structure (LSS) observations. The status and future promise of this enterprise is described. Current band-powers in -space are consistent with a DeltaT flat in frequency and broadly follow inflation-based expectations. That the levels are approximately (10(-5))2 provides strong support for the gravitational instability theory, while the Far Infrared Absolute Spectrophotometer (FIRAS) constraints on energy injection rule out cosmic explosions as a dominant source of LSS. Band-powers at 100 suggest that the universe could not have re-ionized too early. To get the LSS of Cosmic Background Explorer (COBE)-normalized fluctuations right provides encouraging support that the initial fluctuation spectrum was not far off the scale invariant form that inflation models prefer: e.g., for tilted Lambda cold dark matter sequences of fixed 13-Gyr age (with the Hubble constant H0 marginalized), ns = 1.17 +/- 0.3 for Differential Microwave Radiometer (DMR) only; 1.15 +/- 0.08 for DMR plus the SK95 experiment; 1.00 +/- 0.04 for DMR plus all smaller angle experiments; 1.00 +/- 0.05 when LSS constraints are included as well. The CMB alone currently gives weak constraints on Lambda and moderate constraints on Omegatot, but theoretical forecasts of future long duration balloon and satellite experiments are shown which predict percent-level accuracy among a large fraction of the 10+ parameters characterizing the cosmic structure formation theory, at least if it is an inflation variant.

  20. 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.

  1. 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.

  2. 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.

  3. 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.; hide

    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.

  4. The Primordial Inflation Explorer (PIXIE): a nulling polarimeter for cosmic microwave background observations

    SciTech Connect

    Kogut, A.; Fixsen, D.J.; Chuss, D.T.; Dwek, E.; Moseley, S.H.; Wollack, E.J. E-mail: Dale.J.Fixsen@nasa.gov E-mail: Eliahu.Dwek-1@nasa.gov; and others

    2011-07-01

    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 μm 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{sup −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. Cosmic Microwave Background Mapping

    NASA Astrophysics Data System (ADS)

    Verkhodanov, O. V.; Doroshkevich, A. G.

    2012-03-01

    The last decade of research in cosmology was connected with the ambitious experiments including space and ground base observations. Among the most impressive results of these investigations are the measurements of the cosmic microwave background (CMB) radiation like WMAP* and Planck. Exactly from the CMB studies, we have started the epoch of the precision cosmology when generally the values of cosmological parameters have been known and present research is devoted to improvement of the precision. These achievements are connected with both the creation of the new facilities in millimeter and submillimeter astronomy (e.g., satellites, receivers, antennas, computers) and development of the methods for the CMB data analysis. Actually, the process of data analysis contains several technical stages including 1. Registration of time-ordered data (TOD) 2. Pixelization of the CMB data - map preparation 3. Component separation 4. Map statistics analysis 5. Map - spherical harmonics transformation 6. C(l)-spectrum calculation and spectrum statistics analysis 7. Cosmological parameters estimation Starting from the cosmic background explorer (COBE) experiment using the so-called Quadrilateralized Sky Cube Projection (see [1-3]), the problem of the whole sky CMB pixelization has attracted great interest and many such schemes were developed. Let us note however that accurate pixelization of the CMB data on the sphere is very important but not the final step of analysis. Usually, the next step implies the determination of the coefficients of the spherical harmonic decomposition of the CMB signal for both anisotropy and polarization. This means that some of the pixelization schemes provide a very accurate map but are inconvenient for further decomposition. This also means that the choice of suitable pixelization schemes depends upon the general goals of the investigation. In this review, we consider several of the most popular sky map pixelization schemes and link them with the

  6. 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.

  7. Cosmic Background Radiation

    NASA Astrophysics Data System (ADS)

    Sidharth, B. G.; Valluri, S. R.

    2015-08-01

    It is shown that a collection of photons with nearly the same frequency exhibits a "condensation" type of phenomenon corresponding to a peak intensity. The observed cosmic background radiation can be explained from this standpoint. We have obtained analogous results by extremization of the occupation number for photons with the use of the Lambert W function. Some of the interesting applications of this function are briefly discussed in the context of graphene which exhibits an interesting two dimensional structure with several characteristic properties and diverse practical applications.

  8. 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.

  9. Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Mather, John; Hinshaw, Gary; Page, Lyman

    The cosmic microwave background (CMB) radiation, the relic of the early phases of the expanding universe, is bright, full of information, and difficult to measure. Along with the recession of galaxies and the primordial nucleosynthesis, it is one of the strongest signs that the Hot Big Bang Model of the universe is correct. It is brightest around 2 mm wavelength, has a temperature of T_{cmb} = 2.72548 ± 0.00057 K, and has a blackbody spectrum within 50 parts per million. Its spatial fluctuations (around 0.01% on 1{}^{circ } scales) are possibly the relics of quantum mechanical processes in the early universe, modified by processes up to the decoupling at a redshift of about 1,000 (when the primordial plasma became mostly transparent). In the cold dark matter (DM) model with cosmic acceleration (Λ CDM), the fluctuation statistics are consistent with the model of inflation and can be used to determine other parameters within a few percent, including the Hubble constant, the Λ constant, the densities of baryonic and dark matter, and the primordial fluctuation amplitude and power spectrum slope. In addition, the polarization of the fluctuations reveals the epoch of reionization at a redshift approximately twice that determined from the Gunn-Peterson trough due to optically thick Lyman α absorption in QSO spectra. It is of historic importance, and a testament to the unity of theory and experiment, that we now have a standard model of cosmology that is consistent with all of the observations.Current observational challenges include (1) improvement of the spectrum distortion measurements, especially at long wavelengths, where the measured background is unexpectedly bright; (2) the search for the B-mode polarization (the divergence-free part of the polarization map), arising from propagating gravitational waves; and (3) the extension of fluctuation measurements to smaller angular scales. Much more precise spectrum observations near 2 mm are likely and would test some

  10. An overview of the Cosmic Background Explorer (COBE) and its observations - New sky maps of the early universe

    NASA Technical Reports Server (NTRS)

    Smoot, George F.

    1992-01-01

    This paper discusses the three instruments aboard NASA's Cosmic Background Explorer (COBE) satellite and presents early results obtained from the first six months of observations. The three instruments (FIRAS, DMR, and DIRBE) have operated well and produced significant new results. The FIRAS measurement of the CMB spectrum supports the standard Big Bang model. The maps made from the DMR instrument measurements show a spatially smooth early universe. The maps of galactic and zodiacal emission produced by the DIRBE instrument are needed to identify the foreground emissions from extragalactic and thus to interpret its and the other COBE results in terms of events in the early universe.

  11. Cosmic Tachyon Background Radiation

    NASA Astrophysics Data System (ADS)

    Tomaschitz, Roman

    The equilibrium statistical mechanics of a background radiation of superluminal particles is investigated, based on a vectorial wave equation for tachyons of the Proca type. The partition function, the spectral energy density, and the various thermodynamic variables of an ideal Bose gas of tachyons in an open Robertson-Walker cosmology are derived. The negative mass square in the wave equation changes the frequency scaling in the Rayleigh-Jeans law, and there are also significant changes in the low temperature regime as compared to the microwave background, in particular in the caloric and thermal equations of state.

  12. 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.

  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. 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.

  15. Cosmic Needles versus Cosmic Microwave Background Radiation

    NASA Astrophysics Data System (ADS)

    Li, Aigen

    2003-02-01

    It has been suggested by a number of authors that the 2.7 K cosmic microwave background (CMB) radiation might have arisen from the radiation of ``Population III'' objects thermalized by conducting cosmic graphite/iron needle-shaped dust. Due to a lack of an accurate solution to the absorption properties of exceedingly elongated grains, in existing literature which studies the CMB thermalizing process they are generally modeled as (1) needle-like spheroids in terms of the Rayleigh approximation, (2) infinite cylinders, and (3) antennae. We show here that the Rayleigh approximation is not valid since the Rayleigh criterion is not satisfied for highly conducting needles. We also show that the available intergalactic iron dust, if modeled as infinite cylinders, is not sufficient to supply the required opacity at long wavelengths to obtain the observed isotropy and Planckian nature of the CMB. If appealing to the antenna theory, conducting iron needles with exceedingly large elongations ( >104) appear able to provide sufficient opacity to thermalize the CMB within the iron density limit. But the applicability of the antenna theory to exceedingly thin needles of nanometer/micrometer thickness has not yet been verified.

  16. The test facility requirements for the thermal vacuum thermal balance test of the Cosmic Background Explorer Observatory

    NASA Technical Reports Server (NTRS)

    Milam, Laura J.

    1990-01-01

    The Cosmic Background Explorer Observatory (COBE) underwent 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.

  17. Preliminary spectral observations of the Galaxy with a 7 deg beam by the Cosmic Background Explorer (COBE)

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    The FIR absolute spectrophotometer (FIRAS) on the Cosmic Background Explorer (COBE) has carried out the first all-sky spectral line survey in the FIR region, as well as mapping spectra of the Galactic dust distribution at below 100 microns. Lines of forbidden C I, C II, and N II, as well as of CO are all clearly detected. The mean line intensities are interpreted in terms of the heating and cooling of the multiple phases of the interstellar gas. In addition, an average spectrum of the galaxy is constructed and searched for weak lines. The spectrum of the galaxy observed by FIRAS has two major components: a continuous spectrum due to interstellar dust heated by starlight, and a line spectrum dominated by the strong 158-micron line from singly ionized carbon, with a spatial distribution similar to the dust distribution, and a luminosity of 0.3 percent of the dust luminosity. There are in addition moderately strong 122- and 205.3-micron lines, identified as coming from singly-ionized nitrogen. Maps of the emission by dust and forbidden C II and N II are presented.

  18. Cosmic Microwave Background Data Analysis

    NASA Astrophysics Data System (ADS)

    Paykari, Paniez; Starck, Jean-Luc Starck

    2012-03-01

    About 400,000 years after the Big Bang the temperature of the Universe fell to about a few thousand degrees. As a result, the previously free electrons and protons combined and the Universe became neutral. This released a radiation which we now observe as the cosmic microwave background (CMB). The tiny fluctuations* in the temperature and polarization of the CMB carry a wealth of cosmological information. These so-called temperature anisotropies were predicted as the imprints of the initial density perturbations which gave rise to the present large-scale structures such as galaxies and clusters of galaxies. This relation between the present-day Universe and its initial conditions has made the CMB radiation one of the most preferred tools to understand the history of the Universe. The CMB radiation was discovered by radio astronomers Arno Penzias and Robert Wilson in 1965 [72] and earned them the 1978 Nobel Prize. This discovery was in support of the Big Bang theory and ruled out the only other available theory at that time - the steady-state theory. The crucial observations of the CMB radiation were made by the Far-Infrared Absolute Spectrophotometer (FIRAS) instrument on the Cosmic Background Explorer (COBE) satellite [86]- orbited in 1989-1996. COBE made the most accurate measurements of the CMB frequency spectrum and confirmed it as being a black-body to within experimental limits. This made the CMB spectrum the most precisely measured black-body spectrum in nature. The CMB has a thermal black-body spectrum at a temperature of 2.725 K: the spectrum peaks in the microwave range frequency of 160.2 GHz, corresponding to a 1.9mmwavelength. The results of COBE inspired a series of ground- and balloon-based experiments, which measured CMB anisotropies on smaller scales over the next decade. During the 1990s, the first acoustic peak of the CMB power spectrum (see Figure 5.1) was measured with increasing sensitivity and by 2000 the BOOMERanG experiment [26] reported

  19. [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.

  20. The cosmic infrared background experiment

    NASA Astrophysics Data System (ADS)

    Bock, James; Battle, John; Cooray, Asantha; Kawada, Mitsunobu; Keating, Brian; Lange, Andrew; Lee, Dae-Hea; Matsumoto, Toshio; Matsuura, Shuji; Pak, Soojong; Renbarger, Tom; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko; Watabe, Toyoki

    2006-03-01

    The extragalactic background, based on absolute measurements reported by DIRBE and IRTS at 1.2 and 2.2 μm, exceeds the brightness derived from galaxy counts by up to a factor 5. Furthermore, both DIRBE and the IRTS report fluctuations in the near-infrared sky brightness that appear to have an extra-galactic origin, but are larger than expected from local ( z = 1-3) galaxies. These observations have led to speculation that a new class of high-mass stars or mini-quasars may dominate primordial star formation at high-redshift ( z ˜ 10-20), which, in order to explain the excess in the near-infrared background, must be highly luminous but produce a limited amount of metals and X-ray photons. Regardless of the nature of the sources, if a significant component of the near-infrared background comes from first-light galaxies, theoretical models generically predict a prominent near-infrared spectral feature from the redshifted Lyman cutoff, and a distinctive fluctuation power spectrum. We are developing a rocket-borne instrument (the Cosmic Infrared Background ExpeRiment, or CIBER) to search for signatures of primordial galaxy formation in the cosmic near-infrared extra-galactic background. CIBER consists of a wide-field two-color camera, a low-resolution absolute spectrometer, and a high-resolution narrow-band imaging spectrometer. The cameras will search for spatial fluctuations in the background on angular scales from 7″ to 2°, where a first-light galaxy signature is expected to peak, over a range of angular scales poorly covered by previous experiments. CIBER will determine if the fluctuations reported by the IRTS arise from first-light galaxies or have a local origin. In a short rocket flight CIBER has sensitivity to probe fluctuations 100× fainter than IRTS/DIRBE, with sufficient resolution to remove local-galaxy correlations. By jointly observing regions of the sky studied by Spitzer and ASTRO-F, CIBER will build a multi-color view of the near

  1. The Cosmic Infrared Background Experiment

    NASA Astrophysics Data System (ADS)

    Bock, James; Battle, J.; Cooray, A.; Hristov, V.; Kawada, M.; Keating, B.; Lee, D.; Matsumoto, T.; Matsuura, S.; Nam, U.; Renbarger, T.; Sullivan, I.; Tsumura, K.; Wada, T.; Zemcov, M.

    2009-01-01

    We are developing the Cosmic Infrared Background ExpeRiment (CIBER) to search for signatures of first-light galaxy emission in the extragalactic background. The first generation of stars produce characteristic signatures in the near-infrared extragalactic background, including a redshifted Ly-cutoff feature and a characteristic fluctuation power spectrum, that may be detectable with a specialized instrument. CIBER consists of two wide-field cameras to measure the fluctuation power spectrum, and a low-resolution and a narrow-band spectrometer to measure the absolute background. The cameras will search for fluctuations on angular scales from 7 arcseconds to 2 degrees, where the first-light galaxy spatial power spectrum peaks. The cameras have the necessary combination of sensitivity, wide field of view, spatial resolution, and multiple bands to make a definitive measurement. CIBER will determine if the fluctuations reported by Spitzer arise from first-light galaxies. The cameras observe in a single wide field of view, eliminating systematic errors associated with mosaicing. Two bands are chosen to maximize the first-light signal contrast, at 1.6 um near the expected spectral maximum, and at 1.0 um; the combination is a powerful discriminant against fluctuations arising from local sources. We will observe regions of the sky surveyed by Spitzer and Akari. The low-resolution spectrometer will search for the redshifted Lyman cutoff feature in the 0.7 - 1.8 um spectral region. The narrow-band spectrometer will measure the absolute Zodiacal brightness using the scattered 854.2 nm Ca II Fraunhofer line. The spectrometers will test if reports of a diffuse extragalactic background in the 1 - 2 um band continues into the optical, or is caused by an under estimation of the Zodiacal foreground. We report performance of the assembled and tested instrument as we prepare for a first sounding rocket flight in early 2009. CIBER is funded by the NASA/APRA sub-orbital program.

  2. 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).

  3. Measurements of the cosmic background radiation

    NASA Technical Reports Server (NTRS)

    Weiss, R.

    1980-01-01

    Measurements of the attributes of the 2.7-K microwave background radiation (CBR) are reviewed, with emphasis on the analytic phase of CBR studies. Methods for the direct measurement of the CBR spectrum are discussed; attention is given to receivers, antennas, absolute receiver calibration, atmospheric emission and absorption, the galactic background contribution, the analysis of LF measurements, and recent HF observations of the CBR spectrum. Measurements of the large-angular-scale intensity distribution of the CBR (the most convincing evidence that the radiation is of cosmological origin) are examined, along with limits on the linear polarization of the CBR. A description is given of the NASA-sponsored Cosmic Background Explorer (COBE) satellite mission. The results of the COBE mission will be a set of sky maps showing, in the wave number range from 1 to 10,000 kaysers, the galactic background radiation due to synchrotron emission from galactic cosmic rays, to diffuse thermal emission from H II regions, and to diffuse thermal emission from interstellar and interplanetary dust, as well as a residue consisting of the CBR and whatever other cosmological background might exist.

  4. Measurements of the cosmic background radiation

    SciTech Connect

    Weiss, R.

    1980-01-01

    Measurements of the attributes of the 2.7-K microwave background radiation (CBR) are reviewed, with emphasis on the analytic phase of CBR studies. Methods for the direct measurement of the CBR spectrum are discussed. Attention is given to receivers, antennas, absolute receiver calibration, atmospheric emission and absorption, the galactic background contribution, the analysis of LF measurements, and recent HF observations of the CBR spectrum. Measurements of the large-angular-scale intensity distribution of the CBR (the most convincing evidence that the radiation is of cosmological origin) are examined, along with limits on the linear polarization of the CBR. A description is given of the NASA-sponsored Cosmic Background Explorer (COBE) satellite mission. The results of the COBE mission will be a set of sky maps showing, in the wave number range from 1 to 10,000 kaysers, the galactic background radiation due to synchrotron emission from galactic cosmic rays, to diffuse thermal emission from H II regions, and to diffuse thermal emission from interstellar and interplanetary dust, as well as a residue consisting of the CBR and whatever other cosmological background might exist.

  5. BOOK REVIEW: The Cosmic Microwave Background The Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Coles, Peter

    2009-08-01

    With the successful launch of the European Space Agency's Planck satellite earlier this year the cosmic microwave background (CMB) is once again the centre of attention for cosmologists around the globe. Since its accidental discovery in 1964 by Arno Penzias and Robert Wilson, this relic of the Big Bang has been subjected to intense scrutiny by generation after generation of experiments and has gradually yielded up answers to the deepest questions about the origin of our Universe. Most recently, the Wilkinson Microwave Anisotropy Probe (WMAP) has made a full-sky analysis of the pattern of temperature and polarization variations that helped establish a new standard cosmological model, confirmed the existence of dark matter and dark energy, and provided strong evidence that there was an epoch of primordial inflation. Ruth Durrer's book reflects the importance of the CMB for future developments in this field. Aimed at graduate students and established researchers, it consists of a basic introduction to cosmology and the theory of primordial perturbations followed by a detailed explanation of how these manifest themselves as measurable variations in the present-day radiation field. It then focuses on the statistical methods needed to obtain accurate estimates of the parameters of the standard cosmological model, and finishes with a discussion of the effect of gravitational lensing on the CMB and on the evolution of its spectrum. The book apparently grew out of various lecture notes on CMB anisotropies for graduate courses given by the author. Its level and scope are well matched to the needs of such an audience and the presentation is clear and well-organized. I am sure that this book will be a useful reference for more senior scientists too. If I have a criticism, it is not about what is in the book but what is omitted. In my view, one of the most exciting possibilities for future CMB missions, including Planck, is the possibility that they might discover physics

  6. 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.

  7. Physics of the Cosmic Microwave Background Radiation

    NASA Astrophysics Data System (ADS)

    Wands, David; Piattella, Oliver F.; Casarini, Luciano

    The cosmic microwave background (CMB) radiation provides a remarkable window onto the early universe, revealing its composition and structure. In these lectures we review and discuss the physics underlying the main features of the CMB.

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

    PubMed

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

    2007-12-07

    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.

  9. The Explorer of Diffuse Galactic Emission (EDGE): Determination of Large-Scale Structure Evolution from Measurement of the Anisotropy of the Cosmic Infrared Background

    NASA Technical Reports Server (NTRS)

    Silverberg, R. F.; Cheng, E. S.; Cottingham, D. A.; Fixsen, D. J.; Meyer, S. S.; Wilson, G. W.

    2004-01-01

    The formation of the first objects, stars and galaxies and their subsequent evolution remain a cosmological unknown. Few observational probes of these processes exist. The Cosmic Infrared Background (CIB) originates from this era, and can provide information to test models of both galaxy evolution and the growth of primordial structure. The Explorer of Diffuse Galactic Emission (EDGE) is a proposed balloon-borne mission designed to measure the spatial fluctuations in the CIB from 200 micrometers to 1 millimeter on 6' to 3 degree scales with 2 microKelvin sensitivity/resolution element. Such measurements would provide a sensitive probe of the large-scale variation in protogalaxy density at redshifts approximately 0.5-3. In this paper, we present the scientific justification for the mission and show a concept for the instrument and observations.

  10. Cosmic background explorer (COBE) navigation with TDRSS one-way return-link Doppler in the post-helium-venting phase

    NASA Astrophysics Data System (ADS)

    Nemesure, M.; Dunham, J.; Maher, M.; Teles, J.; Jackson, J.

    1991-10-01

    A navigation experiment was performed which establishes Ultra-Stable Oscillator (USO) frequency stabilized one way return link Doppler TDRSS tracking data as a feasible option for mission orbit determination support at the Goddard Space Center Flight Dynamics Facility. The study was conducted using both one way and two way Tracking and Data Relay Satellite System (TDRSS) tracking measurements for the Cosmic Background Explorer (COBE) spacecraft. Tracking data for a 4 week period immediately follow the depletion of the helium supply was used. The study showed that, for both definitive orbit solution and short term orbit prediction (up to 4 weeks), orbit determination results based on one way return link Doppler tracking measurements are comparable to orbit determination results based on two way range and two way Doppler tracking measurements.

  11. Cosmic background explorer (COBE) navigation with TDRSS one-way return-link Doppler in the post-helium-venting phase

    NASA Technical Reports Server (NTRS)

    Nemesure, M.; Dunham, J.; Maher, M.; Teles, J.; Jackson, J.

    1991-01-01

    A navigation experiment was performed which establishes Ultra-Stable Oscillator (USO) frequency stabilized one way return link Doppler TDRSS tracking data as a feasible option for mission orbit determination support at the Goddard Space Center Flight Dynamics Facility. The study was conducted using both one way and two way Tracking and Data Relay Satellite System (TDRSS) tracking measurements for the Cosmic Background Explorer (COBE) spacecraft. Tracking data for a 4 week period immediately follow the depletion of the helium supply was used. The study showed that, for both definitive orbit solution and short term orbit prediction (up to 4 weeks), orbit determination results based on one way return link Doppler tracking measurements are comparable to orbit determination results based on two way range and two way Doppler tracking measurements.

  12. 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.

  13. Cosmic Coincidences: Investigations for Neutron Background Suppression

    PubMed Central

    Heimbach, Craig R.

    2007-01-01

    Two experimental investigations were made in order to reduce background counts in neutron detectors. Each investigation relied upon the fact that neutron background is largely due to cosmic ray interactions with the air and ground. The first attempt was to look at neutron arrival times. Neutron events close in time were taken to have been of a common origin due to cosmic rays. The second investigation was similar, but based on coincident neutron/muon events. The investigations showed only a small effect, not practical for the suppression of neutron background. PMID:27110457

  14. Cosmic Coincidences: Investigations for Neutron Background Suppression.

    PubMed

    Heimbach, Craig R

    2007-01-01

    Two experimental investigations were made in order to reduce background counts in neutron detectors. Each investigation relied upon the fact that neutron background is largely due to cosmic ray interactions with the air and ground. The first attempt was to look at neutron arrival times. Neutron events close in time were taken to have been of a common origin due to cosmic rays. The second investigation was similar, but based on coincident neutron/muon events. The investigations showed only a small effect, not practical for the suppression of neutron background.

  15. Fluctuations in the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Zaldarriaga, Matias

    1998-06-01

    In this thesis we investigate several aspects related to the theory of fluctuations in the Cosmic Microwave Background. We develop a new algorithm to calculate the angular power spectrum of the anisotropies which is two orders of magnitude faster than the standard Boltzmann hierarchy approach (Chapter 3). The new algorithm will become essential when comparing the observational results of the next generation of CMB experiments with theoretical predictions. The parameter space of the models is so large that an exhaustive exploration to find the best fit model will only be feasible with this new type of algorithm. We also investigate the polarization properties of the CMB field. We develop a new formalism to describe the statistics of the polarization variables that takes into account their spin two nature (Chapter 2). In Chapter 4 we explore several physical effects that create distinct features in the polarization power spectrum. We study the signature of the reionization of the universe and a stochastic background of gravitational waves. We also describe how the polarization correlation functions can be used to test the causal structure of the universe. Finally in Chapter 5 we quantify the amount of information the next generation of satellites can obtain by measuring both temperature and polarization anisotropies. We calculate the expected error bars on the cosmological parameters for the specifications of the MAP and Planck satellite missions.

  16. Cosmic Microwave Background spectral distortions from cosmic string loops

    SciTech Connect

    Anthonisen, Madeleine; Brandenberger, Robert; Laguë, Alex; Morrison, Ian A.; Xia, Daixi E-mail: rhb@physics.mcgill.ca E-mail: imorrison@physics.mcgill.ca

    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{sup −15} and G μ ∼ 10{sup −12}, thus ruling out particle physics models yielding these kind of intermediate-scale cosmic strings.

  17. Robust Constraint on Cosmic Textures from the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Feeney, Stephen M.; Johnson, Matthew C.; Mortlock, Daniel J.; Peiris, Hiranya V.

    2012-06-01

    Fluctuations in the cosmic microwave background (CMB) contain information which has been pivotal in establishing the current cosmological model. These data can also be used to test well-motivated additions to this model, such as cosmic textures. Textures are a type of topological defect that can be produced during a cosmological phase transition in the early Universe, and which leave characteristic hot and cold spots in the CMB. We apply Bayesian methods to carry out a rigorous test of the texture hypothesis, using full-sky data from the Wilkinson Microwave Anisotropy Probe. We conclude that current data do not warrant augmenting the standard cosmological model with textures. We rule out at 95% confidence models that predict more than 6 detectable cosmic textures on the full sky.

  18. 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.

  19. Cosmic Microwave Background Bispectrum from Recombination

    NASA Astrophysics Data System (ADS)

    Huang, Zhiqi; Vernizzi, Filippo

    2013-03-01

    We compute the cosmic microwave background temperature bispectrum generated by nonlinearities at recombination on all scales. We use CosmoLib2nd, a numerical Boltzmann code at second order to compute cosmic microwave background bispectra on the full sky. We consistently include all effects except gravitational lensing, which can be added to our result using standard methods. The bispectrum is peaked on squeezed triangles and agrees with the analytic approximation in the squeezed limit at the few percent level for all the scales where this is applicable. On smaller scales, we recover previous results on perturbed recombination. For cosmic-variance limited data to lmax⁡=2000, its signal-to-noise ratio is S/N=0.47, corresponding to fNLeff=-2.79, and will bias a local signal by fNLloc≃0.82.

  20. 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.

  1. 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.

  2. Topological analysis of COBE-DMR cosmic microwave background maps

    NASA Astrophysics Data System (ADS)

    Torres, Sergio

    1994-03-01

    Geometric characteristics of random fields are exploited to test the consistency of density perturbation model spectra with Cosmic Background Explorer (COBE) data. These cosmic microwave background (CMB) maps are analyzed using the number of anisotropy hot spots and their boundary curvature. CMB maps which account for instrumental effects and sky coverage are Monte Carlo generated. These simulations show that a scale-invariant Harrison-Zeldovich primordial Gaussian density fluctuation spectrum is consistent with the data. The CMB fluctuation coherence angle, based on boundary curvature, gives a spectral index n = 1.2 +/- 0.3.

  3. Can one measure the Cosmic Neutrino Background?

    NASA Astrophysics Data System (ADS)

    Faessler, Amand; Hodák, Rastislav; Kovalenko, Sergey; Šimkovic, Fedor

    The Cosmic Microwave Background (CMB) yields information about our Universe at around 380,000 years after the Big Bang (BB). Due to the weak interaction of the neutrinos with matter, the Cosmic Neutrino Background (CNB) should give information about a much earlier time of our Universe, around one second after the BB. Probably, the most promising method to "see" the CNB is the capture of the electron neutrinos from the Background by Tritium, which then decays into 3He and an electron with the energy of the the Q-value = 18.562 keV plus the electron neutrino rest mass. The "KArlsruhe TRItium Neutrino" (KATRIN) experiment, which is in preparation, seems presently the most sensitive proposed method for measuring the electron antineutrino mass. At the same time, KATRIN can also look by the reaction νe(˜1.95K) + 3H → 3He + e-(Q = 18.6keV + mνec2). The capture of the Cosmic Background Neutrinos (CNB) should show in the electron spectrum as a peak by the electron neutrino rest mass above Q. Here, the possibility to see the CNB with KATRIN is studied. A detection of the CNB by KATRIN seems not to be possible at the moment. But KATRIN should be able to determine an upper limit for the local electron neutrino density of the CNB.

  4. Can one measure the Cosmic Neutrino Background?

    NASA Astrophysics Data System (ADS)

    Faessler, Amand; Hodák, Rastislav; Kovalenko, Sergey; Šimkovic, Fedor

    The Cosmic Microwave Background (CMB) yields information about our Universe at around 380,000 years after the Big Bang (BB). Due to the weak interaction of the neutrinos with matter, the Cosmic Neutrino Background (CNB) should give information about a much earlier time of our Universe, around one second after the BB. Probably, the most promising method to “see” the CNB is the capture of the electron neutrinos from the Background by Tritium, which then decays into 3He and an electron with the energy of the the Q-value = 18.562keV plus the electron neutrino rest mass. The “KArlsruhe TRItium Neutrino” (KATRIN) experiment, which is in preparation, seems presently the most sensitive proposed method for measuring the electron antineutrino mass. At the same time, KATRIN can also look by the reaction νe(˜ 1.95K) +3H →3He + e‑(Q = 18.6keV + m νec2). The capture of the Cosmic Background Neutrinos (CNB) should show in the electron spectrum as a peak by the electron neutrino rest mass above Q. Here, the possibility to see the CNB with KATRIN is studied. A detection of the CNB by KATRIN seems not to be possible at the moment. But KATRIN should be able to determine an upper limit for the local electron neutrino density of the CNB.

  5. 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.

  6. 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).

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Sadegh Movahed, M.; Khosravi, Shahram

    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 Gμgtrsim4 × 10-9 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 Gμgtrsim5.8 × 10-9.

  9. 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}.

  10. The Cosmic Microwave Background and its Polarization

    NASA Astrophysics Data System (ADS)

    Wollack, Edward

    2017-01-01

    The subtle spatial variations in the cosmic microwave background (CMB) radiation provide a unique astrophysical probe of the early Universe. Characterization of this relic radiation and its polarization have the power to reveal and constrain the properties of light astroparticle species, long wave gravitational radiation, and intervening mass concentrations. Recent advances in theory, observation, and instrumentation have set the stage to experimentally confront the inflationary paradigm via precision polarimetric surveys of the CMB. Current and proposed future observational efforts from the ground, balloon, and spaceborne platforms will be briefly surveyed in this presentation. Recent community activities by the Inflation Probe Science Interest Group (IPSIG) will also be presented.

  11. Cosmic X-ray background and solitars.

    NASA Astrophysics Data System (ADS)

    Chiu, H.-Y.

    In this paper the authors has examined the observational consequences of a class of new astronomical objects proposed by Friedberg, Lee and Pang, called solitars which are degenerate vacuum states embedded with particles. A study is made to include finite temperature effect and pair creation. Quark is believed to be the only species that can exist in the interior of solitars. Massive quark solitars are primarily X-ray emitters and may account for the large unexplained thermal component of the cosmic X-ray background.

  12. Ponderable soliton stars and cosmic background radiation

    SciTech Connect

    Chiu, Hongyee )

    1990-12-01

    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. 17 refs.

  13. 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.

  14. Decoherence in the cosmic background radiation

    NASA Astrophysics Data System (ADS)

    Franco, Mariano; Calzetta, Esteban

    2011-07-01

    In this paper, we analyze the possibility of detecting nontrivial quantum phenomena in observations of the temperature anisotropy of the cosmic background radiation (CBR), for example, if the Universe could be found in a coherent superposition of two states corresponding to different CBR temperatures. Such observations are sensitive to scalar primordial fluctuations but insensitive to tensor fluctuations, which are therefore converted into an environment for the former. Even for a free inflaton field minimally coupled to gravity, scalar-tensor interactions induce enough decoherence among histories of the scalar fluctuations as to render them classical under any realistic probe of their amplitudes.

  15. 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.

  16. 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.

  17. 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.

  18. Cosmology with the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Souradeep, Tarun

    The standard model of cosmology must not only explain the dynamics of the homogeneous background universe, but also satisfactorily describe the perturbed universe - the generation, evolution and finally, the formation of large-scale structures in the universe. Cosmic microwave background (CMB) has been by far the most influential cosmological observation driving advances in current cosmology. Exquisite measurements from CMB experiments have seen the emergence of a concordant cosmological model. Besides precise determination of various parameters of the standard cosmological model, observations have also established some important basic tenets that underlie models of cosmology and structure formation in the universe. The article reviews this aspect of recent progress in cosmology for a general science reader.

  19. Extracting the cosmic history from diffuse backgrounds

    NASA Astrophysics Data System (ADS)

    Pritchard, Jonathan Robin

    The modern picture of the Universe resembles a detective novel with the first page and the middle chapters removed and the ending unwritten. Observations of the cosmic microwave background (CMB) have given cosmologists a snapshot of the Universe when it was only a few hundred thousand years old. At the same time, large galaxy surveys, such as SDSS and 2dF, have shed light on the distribution of matter in the local Universe. From the combination of these two data sets, cosmological parameters can be measured to percent accuracy. Two main frontiers remain: inflation, the domain of high-energy physics, and the epoch of reionization, the period connecting the linear age of the CMB with that of the present day. Added to this are the indications from supernovae of an acceleration in the expansion rate suggesting modifications to gravity or the presence of an esoteric new form of energy.In this work, we investigate uses of various radiation backgrounds for probing the different epochs of this cosmic history. We examine (i) the use of B-mode polarization of the CMB induced by an inflationary gravitational wave background to probe inflation, (ii) the importance of higher Lyman series photons in pumping of the 21 cm line and the consequences for the 21 cm signal from the first stars, (iii) the atomic physics of Lyman series photon scattering in the intergalactic medium and the consequences for heating and coupling of the 21 cm line, (iv) the possibility of using the 21 cm line to probe inhomogeneous X-ray heating of the IGM by a population of early X-ray sources, and (v) the impact of inhomogeneous reionization on galaxy formation and the consequences for our ability to use large galaxy surveys to constrain dark energy. Together, these chapters significantly extend our understanding of important windows into the early Universe.

  20. Data analysis of cosmic microwave background experiments

    NASA Astrophysics Data System (ADS)

    Abroe, Matthew Edmund

    2004-12-01

    The cosmic microwave background (CMB) is a powerful tool for determining and constraining the fundamental properties of our universe. In this thesis we present various computational and statistical techniques used to analyze datasets from CMB experiments, and apply them to both simulated and actual datasets. The algorithms presented in this thesis perform a variety of tasks in relation to the goal of extracting scientific information from CMB data sets. The CMB anisotropy power spectrum is sensitive to numerous parameters that determine the evolutionary and large scale properties of our universe. Now that numerous experiments have mapped the CMB intensity fluctuations on overlapping regions of the sky it is important to ensure that the various experiments are indeed observing the same signal. We cross-correlate the cosmic microwave background temperature anisotropy maps from the WMAP, MAXIMA-I, and MAXIMA-II experiments. The results conclusively show that the three experiments not only display the same statistical properties of the CMB anisotropy, but also detect the same features wherever the observed sky areas overlap. We conclude that the contribution of systematic errors to these maps is negligible and that MAXIMA and WMAP have accurately mapped the cosmic microwave background anisotropy. Due to a quadrapole anisotropy at last scattering it is predicted that the CMB photons should be linearly polarized, and that the polarization intensity will be roughly an order of magnitude lower than the intensity fluctuations. Two computationally intensive methods for simulating the CMB polarization signal on the sky are presented. Now that CMB polarization experiments are currently producing data sets new algorithms for analyzing polarization time stream data must be developed and tested. We demonstrate how to generate simulations of a polarization experiment in the temporal domain and apply these simulations to the MAXIPOL case. We develop a maximum likelihood map making

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Cosmic Microwave Background Anisotropy: Python V Results

    NASA Astrophysics Data System (ADS)

    Coble, K.; Dragovan, M.; Kovac, J.; Halverson, N. W.; Holzapfel, W. L.; Knox, L.; Dodelson, S.; Ganga, K.; Peterson, J. B.; Alvarez, D.; Griffin, G.; Newcomb, M.; Miller, K.; Platt, S. R.; Novak, G.

    1999-05-01

    Observations of the microwave sky using the Python telescope in its fifth season of operation at the Amundsen-Scott South Pole Station in Antarctica are presented. The system consists of a 0.75 m off-axis telescope instrumented with a HEMT amplifier-based radiometer having continuum sensitivity from 37-45 GHz in two frequency bands. With a 0.91 x 1.02 deg beam the instrument fully sampled 598 deg(2) of sky, including fields measured during the previous four seasons of Python observations. Interpreting the observed fluctuations as anisotropy in the cosmic microwave background, we place constraints on the angular power spectrum of fluctuations in multipole bands up to l ~ 260. The observed spectrum is consistent with both the COBE experiment and previous Python results. There is no significant contamination from known foregrounds. The results show a discernible rise in the angular power spectrum from large (l ~ 40) to small (l ~ 200) angular scales.

  6. Polarization of the cosmic background radiation

    NASA Astrophysics Data System (ADS)

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

    1981-04-01

    The technique and results of a measurement of the linear polarization of the cosmic background radiation at a wavelength of 9 mm are discussed. Data taken between 1978 May and 1980 February from both the Northern Hemisphere (Berkeley latitude 38 deg N) and the Southern Hemisphere (Lima latitude 12 deg S) over 11 declinations from -37 to +63 deg 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.

  7. 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.

  8. Canny Algorithm, Cosmic Strings and the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Danos, Rebecca J.; Brandenberger, Robert H.

    We describe a new code to search for signatures of cosmic strings in cosmic microwave anisotropy maps. The code implements the Canny algorithm, an edge detection algorithm designed to search for the lines of large gradients in maps. Such a gradient signature which is coherent in position-space is produced by cosmic strings via the Kaiser-Stebbins effect. We test the power of our new code to set limits on the tension of the cosmic strings by analyzing simulated data, with and without cosmic strings. We compare maps with a pure Gaussian scale-invariant power spectrum with maps which have a contribution of a distribution of cosmic strings obeying a scaling solution. The maps have angular scale and angular resolution comparable to what current and future ground-based small-scale cosmic microwave anisotropy experiments will achieve. We present tests of the codes, indicate the limits on the string tension which could be set with the current code, and describe various ways to refine the analysis. Our results indicate that when applied to the data of ongoing cosmic microwave experiments such as the South Pole Telescope project, the sensitivity of our method to the presence of cosmic strings will be more than an order of magnitude better than the limits from existing analyses.

  9. 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.

  10. 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.

  11. Cosmic Infrared Background Fluctuations and Zodiacal Light

    NASA Technical Reports Server (NTRS)

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

    2017-01-01

    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 (near-infrared)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 (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 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 (greater than or approximately equal to 100 arcseconds) 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.

  12. Robustness of cosmic neutrino background detection in the cosmic microwave background

    SciTech Connect

    Audren, Benjamin; Bellini, Emilio; Cuesta, Antonio J.; Verde, Licia; Gontcho, Satya Gontcho A; Pérez-Ràfols, Ignasi; Lesgourgues, Julien; Niro, Viviana; Tram, Thomas

    2015-03-01

    The existence of a cosmic neutrino background can be probed indirectly by CMB experiments, not only by measuring the background density of radiation in the universe, but also by searching for the typical signatures of the fluctuations of free-streaming species in the temperature and polarisation power spectrum. Previous studies have already proposed a rather generic parametrisation of these fluctuations, that could help to discriminate between the signature of ordinary free-streaming neutrinos, or of more exotic dark radiation models. Current data are compatible with standard values of these parameters, which seems to bring further evidence for the existence of a cosmic neutrino background. In this work, we investigate the robustness of this conclusion under various assumptions. We generalise the definition of an effective sound speed and viscosity speed to the case of massive neutrinos or other dark radiation components experiencing a non-relativistic transition. We show that current bounds on these effective parameters do not vary significantly when considering an arbitrary value of the particle mass, or extended cosmological models with a free effective neutrino number, dynamical dark energy or a running of the primordial spectrum tilt. We conclude that it is possible to make a robust statement about the detection of the cosmic neutrino background by CMB experiments.

  13. Fluctuations In The Cosmic Infrared Background Using the Cosmic Infrared Background ExpeRiment (CIBER).

    NASA Astrophysics Data System (ADS)

    Smidt, Joseph; Arai, T.; Battle, J.; Bock, J. J.; Cooray, A.; Frazer, C.; Hristov, V.; Keating, B.; Kim, M.; Lee, D.; Mason, P.; Matsumoto, T.; Mitchell-Wynne, K.; Nam, U.; Renbarger, T.; Smith, A.; Sullivan, I.; Tsumura, K.; Wada, T.; Zemcov, M.

    2012-01-01

    The clustering properties of faint unresolved sources may be probed by examining the anisotropies they create in the Cosmic Infrared Background (CIB). Using information from fluctuations in the CIB at different wavelengths allows us to disentangle how clustering relates to redshift. In this talk, preliminary measurements of clustering using data from the Cosmic Infrared Background ExpeRiment (CIBER), a rocket-borne experiment designed to detect the signatures of unresolved infrared galaxies during reionization, will be discussed. The CIBER payload contains four instruments including two wide field imagers designed to measure fluctuations in the near IR cosmic infrared background (CIB) at 1.0 and 1.6 microns on scales between 0.2 and 100 arcmin in both bands, where the clustering of high-redshift sources is expected to peak. CIBER observations may be combined with Akari/NEP and Spitzer/NDWFS near-infrared surveys to check systematic errors and to fully characterize the electromagnetic spectrum of CIB fluctuations.

  14. Natural inflation: Particle physics models, power-law spectra for large-scale structure, and constraints from the Cosmic Background Explorer

    NASA Astrophysics Data System (ADS)

    Adams, Fred C.; Bond, J. Richard; Freese, Katherine; Frieman, Joshua A.; Olinto, Angela V.

    1993-01-01

    We discuss the particle physics basis for models of natural inflation with pseudo Nambu-Goldstone bosons and study the consequences for large-scale structure of the nonscale-invariant density fluctuation spectra that arise in natural inflation and other models. A pseudo Nambu-Goldstone boson, with a potential of the form V(φ)=Λ4[1+/-cos(φ/f)], can naturally give rise to an epoch of inflation in the early Universe, if f~MPl and Λ~MGUT. Such mass scales arise in particle physics models with a gauge group that becomes strongly interacting at the grand unified theory scale. We work out a specific particle physics example based on the multiple gaugino condensation scenario in superstring theory. We then study the cosmological evolution of and constraints upon these inflation models numerically and analytically. To obtain sufficient inflation with a probability of order 1 and a high enough post-inflation reheat temperature for baryogenesis, we require f>~0.3MPl. The primordial density fluctuation spectrum generated by quantum fluctuations in φ is a non-scale-invariant power law P(k)~kns, with ns~=1-(M2Pl/8πf2) leading to more power on large length scales than the ns=1 Harrison-Zeldovich spectrum. (For the reader primarily interested in large-scale structure, the discussion of this topic is presented in Sec. IV and is intended to be nearly self-contained.) We pay special attention to the prospects of using the enhanced power to explain the otherwise puzzling large-scale clustering of galaxies and clusters and their flows. We find that the standard cold dark matter (CDM) model with 0<~ns<~0.6 could in principle explain these data. However, the microwave background anisotropies recently detected by the Cosmic Background Explorer (COBE) imply such low primordial amplitudes for these CDM models (that is, bias factors b8>~2 for ns<~0.6) that galaxy formation would occur too late to be viable and the large-scale galaxy velocities would be too small. In fact, combining the

  15. 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.

  16. Cosmological constraints from the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Le Dour, M.; Douspis, M.; Bartlett, J. G.; Blanchard, A.

    2000-12-01

    Using an approximate likelihood method adapted to band-power estimates, we analyze the ensemble of first generation cosmic microwave background anisotropy experiments to deduce constraints over a six-dimensional parameter space describing Inflation-generated adiabatic, scalar fluctuations. The basic preferences of simple Inflation scenarios are consistent with the data set: flat geometries (OmT equiv 1-Omk ~ 1) and a scale-invariant primeval spectrum (n ~ 1) are favored. Models with significant negative curvature (OmT < 0.7) are eliminated, while constraints on postive curvature are less stringent. Degeneracies among the parameters prevent independent determinations of the matter density OmM and the cosmological constant Lambda , and the Hubble constant Ho remains relatively unconstrained. We also find that the height of the first Doppler peak relative to the amplitude suggested by data at larger l indicates a high baryon content (Omb h2), almost independently of the other parameters. Besides the overall qualitative advance expected of the next generation experiments, their improved dipole calibrations will be particularly useful for constraining the peak height. Our analysis includes a Goodness-of-Fit statistic applicable to power estimates and which indicates that the maximum likelihood model provides an acceptable fit to the data set.

  17. Cosmic microwave background: Past, future, and present

    SciTech Connect

    Dodelson, S.

    2000-04-10

    Anisotropies in the Cosmic Microwave Background (CMB) carry an enormous amount of information about the early universe. The anisotropy spectrum depends sensitively on close to a dozen cosmological parameters, some of which have never been measured before. Experiments over the next decade will help us extract these parameters, teaching us not only about the early universe, but also about physics at unprecedented energies. One of the dangers now is that scientist are tempted to ignore the present data and rely too much on the future. This would be a shame, for hundreds of individuals have put in a great amount of time building state-of-the-art instruments, making painstaking observations at remote places on and off the globe. It seems unfair to ignore all the data that has been taken to date simply because there will be more and better data in the future. The author then makes the following claims: (1) the theory of CMB anisotropies is understood; (2) using this understanding, he is able to extract from future observations extremely accurate measurements of about ten cosmological parameters; (3) taken at face value, present data determines one of these parameters, the curvature of the universe; and (4) the present data is good enough that the measurements should be believed. The first of these claims are well-known. The last claim is more controversial, but the author presents evidence for it.

  18. Probing inflation with the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Braganca, Vinicius Miranda

    The existence of a quasi-deSitter expansion in the early universe, known as inflation, generates the seeds of large-scale structures and is one of the foundations of the standard cosmological model. The main observational predictions from inflation include the existence of a nearly scale-invariant primordial power spectrum that is imprinted on the cosmic microwave background (CMB), which has been corroborated with remarkable precision in recent years. In single-field slow-roll inflation, a field called the inflaton dominates the energy density of the universe and slowly rolls in an almost perfectly flat potential. In addition, the motion of the inflaton field is friction dominated, with its velocity being completely specified by its position in the field space. This basic scenario is known as the slow-roll approximation and its validity is controlled by the magnitude of the so-called slow-roll parameters. Generalizations of single-field slow-roll inflation provide a wealth of observational signatures in the CMB temperature power spectrum, CMB polarization spectrum, primordial non-Guassianity and in lensing reconstruction. This thesis provides a series of consistency checks between these observables that can distinguish slow-roll violations from alternative explanations.

  19. Technology Development for Cosmic Microwave Background Cosmology

    NASA Astrophysics Data System (ADS)

    Munson, Charles D.

    2017-05-01

    The Cosmic Microwave Background (CMB) offers a unique window into the early universe by probing thermal radiation remaining from the big bang. Due to its low temperature and bright foregrounds, its thorough characterization requires technological advancement beyond the current state-of-the-art. In this thesis, I present the development and fabrication of novel metamaterial silicon optics to improve the sensitivity of current and future CMB telescopes. By machining subwavelength features into the silicon surfaces, traditional antireflection coatings can be replaced by all-silicon metamaterials that significantly reduce reflections over previous approaches. I discuss the design of these structured surfaces and the design and construction of a sophisticated fabrication facility necessary to implement this technology on large diameter (30+ cm) lenses for the Atacama Cosmology Telescope Polarization project (ACTPol). I then apply this metamaterial technology to the development of improved free-space filters for millimeter and sub-millimeter wavelength imaging (focusing specifically on blocking infrared radiation, necessary for current cryogenic detector systems). This produces a highly effective infrared-blocking filter, blocking over 99% of the incident power from a 300 K blackbody while maintaining transmission of better than 99% in a target CMB observing band (between 70 and 170 GHz). I conclude with a discussion of the development of a real-space simulation framework to assist in better understanding current CMB results and forecasting for future experiments. By taking a CMB realization and adding to it accurate real-space modeling of the Sunyaev-Zel'dovich effect and weak lensing distortions (introduced by galaxy clusters), a better understanding of the impacts of large scale structure on the CMB can be obtained.

  20. 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.

  1. 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.

  2. Technology Development for Cosmic Microwave Background Cosmology

    NASA Astrophysics Data System (ADS)

    Munson, Charles D.

    The Cosmic Microwave Background (CMB) offers a unique window into the early universe by probing thermal radiation remaining from the big bang. Due to its low temperature and bright foregrounds, its thorough characterization requires technological advancement beyond the current state-of-the-art. In this thesis, I present the development and fabrication of novel metamaterial silicon optics to improve the sensitivity of current and future CMB telescopes. By machining subwavelength features into the silicon surfaces, traditional antireflection coatings can be replaced by all-silicon metamaterials that significantly reduce reflections over previous approaches. I discuss the design of these structured surfaces and the design and construction of a sophisticated fabrication facility necessary to implement this technology on large diameter (30+ cm) lenses for the Atacama Cosmology Telescope Polarization project (ACTPol). I then apply this metamaterial technology to the development of improved free-space filters for millimeter and sub-millimeter wavelength imaging (focusing specifically on blocking infrared radiation, necessary for current cryogenic detector systems). This produces a highly effective infrared-blocking filter, blocking over 99% of the incident power from a 300 K blackbody while maintaining transmission of better than 99% in a target CMB observing band (between 70 and 170 GHz). I conclude with a discussion of the development of a real-space simulation framework to assist in better understanding current CMB results and forecasting for future experiments. By taking a CMB realization and adding to it accurate real-space modeling of the Sunyaev-Zel'dovich effect and weak lensing distortions (introduced by galaxy clusters), a better understanding of the impacts of large scale structure on the CMB can be obtained.

  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. 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.

  5. Demonstration of Cosmic Microwave Background Delensing Using the Cosmic Infrared Background

    NASA Astrophysics Data System (ADS)

    Larsen, Patricia; Challinor, Anthony; Sherwin, Blake D.; Mak, Daisy

    2016-10-01

    Delensing is an increasingly important technique to reverse the gravitational lensing of the cosmic microwave background (CMB) and thus reveal primordial signals the lensing may obscure. We present a first demonstration of delensing on Planck temperature maps using the cosmic infrared background (CIB). Reversing the lensing deflections in Planck CMB temperature maps using a linear combination of the 545 and 857 GHz maps as a lensing tracer, we find that the lensing effects in the temperature power spectrum are reduced in a manner consistent with theoretical expectations. In particular, the characteristic sharpening of the acoustic peaks of the temperature power spectrum resulting from successful delensing is detected at a significance of 16 σ , with an amplitude of Adelens=1.12 ±0.07 relative to the expected value of unity. This first demonstration on data of CIB delensing, and of delensing techniques in general, is significant because lensing removal will soon be essential for achieving high-precision constraints on inflationary B -mode polarization.

  6. Demonstration of Cosmic Microwave Background Delensing Using the Cosmic Infrared Background.

    PubMed

    Larsen, Patricia; Challinor, Anthony; Sherwin, Blake D; Mak, Daisy

    2016-10-07

    Delensing is an increasingly important technique to reverse the gravitational lensing of the cosmic microwave background (CMB) and thus reveal primordial signals the lensing may obscure. We present a first demonstration of delensing on Planck temperature maps using the cosmic infrared background (CIB). Reversing the lensing deflections in Planck CMB temperature maps using a linear combination of the 545 and 857 GHz maps as a lensing tracer, we find that the lensing effects in the temperature power spectrum are reduced in a manner consistent with theoretical expectations. In particular, the characteristic sharpening of the acoustic peaks of the temperature power spectrum resulting from successful delensing is detected at a significance of 16σ, with an amplitude of A_{delens}=1.12±0.07 relative to the expected value of unity. This first demonstration on data of CIB delensing, and of delensing techniques in general, is significant because lensing removal will soon be essential for achieving high-precision constraints on inflationary B-mode polarization.

  7. 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.

  8. The Mystery of the Cosmic Diffuse Ultraviolet Background Radiation

    NASA Astrophysics Data System (ADS)

    Henry, Richard Conn; Murthy, Jayant; Overduin, James; Tyler, Joshua

    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.

  9. Absolute measurement of the cosmic microwave background at 2 GHz

    NASA Astrophysics Data System (ADS)

    Bersanelli, M.; Bensadoun, M.; de Amici, G.; Levin, S.; Limon, M.; Smoot, G. F.; Vinje, W.

    1994-04-01

    We measured the intensity of the cosmic microwave background (CMB) radiation at a frequency of 2.0 GHz (15 cm wavelength) with a ground-based total-power radio-frequency (RF) gain radiometer calibrated at the antenna aperture with a quasi-free space cold load. The observations were performed from a remote, high-altitude site near the Amundsen-Scott South Pole Station to minimize systematic effects. The measured thermodynamic temperature of the CMB is TCMB = 2.55 +/- 0.14 K (68% confidence level), the limiting factors in the accuracy being the subtraction of the atmospheric and Galactic contributions. The atmospheric emission was evaluated both by direct measurements and by extrapolation from our higher frequency data. The Galactic emission was determined by scaling low-frequency maps and was checked with differential drift scans. Our result is approximately 1 sigma lower than the recent accurate value of TCMB obtained by Cosmic microwave Background Explorer (COBE)-FIRAS above 60 GHz. The temperature of the sky (i.e., CMB plus Galaxy and extragalactic sources) at the south celestial pole with approximately 22 deg resolution is TA, Sky = 2.83 +/- 0.10 K, and its accuracy is limited by the subtraction of atmospheric emission.

  10. Spider casts its web on the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Banks, Michael

    2015-02-01

    An experiment successfully touched down in Antarctica last month after gathering data on the cosmic microwave background (CMB) that could reveal the faint remnants of gravitational waves created during that rapid expansion of the very early universe known as inflation.

  11. Lorentz-violating electrodynamics and the cosmic microwave background.

    PubMed

    Kostelecký, V Alan; Mewes, Matthew

    2007-07-06

    Possible Lorentz-violating effects in the cosmic microwave background are studied. We provide a systematic classification of renormalizable and nonrenormalizable operators for Lorentz violation in electrodynamics and use polarimetric observations to search for the associated violations.

  12. 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. .

  13. Cosmic microwave background science at commercial airline altitudes

    NASA Astrophysics Data System (ADS)

    Feeney, Stephen M.; Gudmundsson, Jon E.; Peiris, Hiranya V.; Verde, Licia; Errard, Josquin

    2017-07-01

    Obtaining high-sensitivity measurements of degree-scale cosmic microwave background (CMB) polarization is the most direct path to detecting primordial gravitational waves. Robustly recovering any primordial signal from the dominant foreground emission will require high-fidelity observations at multiple frequencies, with excellent control of systematics. We explore the potential for a new platform for CMB observations, the Airlander 10 hybrid air vehicle, to perform this task. We show that the Airlander 10 platform, operating at commercial airline altitudes, is well suited to mapping frequencies above 220 GHz, which are critical for cleaning CMB maps of dust emission. Optimizing the distribution of detectors across frequencies, we forecast the ability of Airlander 10 to clean foregrounds of varying complexity as a function of altitude, demonstrating its complementarity with both existing (Planck) and ongoing (C-BASS) foreground observations. This novel platform could play a key role in defining our ultimate view of the polarized microwave sky.

  14. Cosmic Ray Background Analysis for MuLAN

    NASA Astrophysics Data System (ADS)

    Mangialardi, Michael

    2008-10-01

    The goal of the MuLAN experiment is to make a measurement of the muon lifetime to a precision of 1 ppm so that a 5 ppm value of the Fermi coupling constant can be calculated. To do this, a beam of positive muons is stopped in a target surrounded by 340 scintillating detectors arranged in a geodesic around the target. Once the muons stop in the target, they decay, and the product positrons are emitted outward, where they are detected by the scintillators. By examining the spectrum of decay times, the lifetime of positive muons can be calculated. One of the myriad factors affecting this measurement is the background of cosmic ray muons constantly showering upon the detector. To study this background, an angular distribution of the cosmic rays was found, and the rate at which cosmic rays muons ``rain'' upon the detector was calculated. In addition, the cosmic rays were used to examine the timing differences between the individual scintillators.

  15. 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.

  16. 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.

  17. Anomalous cosmic-microwave-background polarization and gravitational chirality.

    PubMed

    Contaldi, Carlo R; Magueijo, João; Smolin, Lee

    2008-10-03

    We consider the possibility that gravity breaks parity, with left and right-handed gravitons coupling to matter with a different Newton's constant and show that this would affect their zero-point vacuum fluctuations during inflation. Should there be a cosmic background of gravity waves, the effect would translate into anomalous cosmic microwave background polarization. Nonvanishing temperature-magnetic (TB) mode [and electric-magnetic mode] components emerge, revealing interesting experimental targets. Indeed, if reasonable chirality is present a TB measurement would provide the easiest way to detect a gravitational wave background. We speculate on the theoretical implications of such an observation.

  18. 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.

  19. 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.

  20. Symmetry and the Cosmic Microwave Background

    NASA Technical Reports Server (NTRS)

    Wollock, Edward J.

    2012-01-01

    A brief historical introduction to the development of observational astronomy and cosmology will be presented. The close relationship between the properties of light, symmetry, and our understanding the contents of our universe will be explored.

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

    SciTech Connect

    Zotti, G. De; Negrello, M.; Castex, G.; Lapi, A.; Bonato, M. E-mail: NegrelloM@cardiff.ac.uk E-mail: lapi@sissa.it

    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{sup −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 ≅ 30% uncertainty.

  2. 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.

  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. Correlation between galactic HI and the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Land, Kate; Slosar, Anže

    2007-10-01

    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.

  6. Big bang nucleosynthesis, cosmic microwave background anisotropies and dark energy

    NASA Astrophysics Data System (ADS)

    Signore, Monique; Puy, Denis

    2002-05-01

    Over the last decade, cosmological observations have attained a level of precision which allows for very detailed comparison with theoretical predictions. We are beginning to learn the answers to some fundamental questions, using information contained in Cosmic Microwave Background Anisotropy (CMBA) data. In this talk, we briefly review some studies of the current and prospected constraints imposed by CMBA measurements on the neutrino physics and on the dark energy. As it was already announced by Scott [1], we present some possible new physics from the Cosmic Microwave Background (CMB). .

  7. 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

  8. Observational aspects of the microwave cosmic background spectrum

    NASA Astrophysics Data System (ADS)

    Martin, D. H.

    The state of the art in measuring and characterizing the cosmic microwave background radiation is assessed. Most measurements have concentrated on wavelengths longer than 3 mm, where the 3 K background Planckian spectrum displays negligible deviation from the Rayleigh-Jeans limit; greater deviations from the limit occur at bands lower than 3 mm. It is noted that techniques used in molecular-line astronomy to distinguish source from noise with precision cannot be used in actual characterization of the background. Radiometers with sensors cooled to liquid He temperatures can be used for more accurate delineation of features of the 3K background below 3 mm. Experiments with various antenna systems and radiometers and concommitant theoretical modeling of expected measurements are reviewed, including the results of tests on rocket-born trials. The design of a new cosmic background radiation antenna and radiometer are presented.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. The cosmic far-infrared background at high galactic latitudes

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Puget, J. L.; Fazio, G. G.

    1976-01-01

    Far-infrared background fluxes from various cosmic sources are predicted. These fluxes lie near the high frequency side of the blackbody radiation spectrum. These sources could account for a significant fraction of the background radiation at frequencies above 400 GHz which might be misinterpreted as a comptonization distortion of the blackbody radiation. Particular attention is paid to the possible contributions from external galaxies, rich clusters of galaxies and from galactic dust emission.

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

    PubMed

    Seshadri, T R; Subramanian, K

    2001-09-03

    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. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Cross-Correlating the Cosmic Infrared and Cosmic X-Ray Background Fluctuations

    NASA Astrophysics Data System (ADS)

    Cooper, Rachel Ann; Cappelluti, Nico; Li, Yanxia; Urry, C. Megan; Guo, Joyce

    2017-01-01

    Studying unresolved (i.e., undetected) sources is a way to probe the faintest, and thus the least understood, source populations. In particular, such studies have suggested a population of high redshift accreting black holes. We present cross-power spectra and coherence between the cosmic infrared and cosmic x-ray background fluctuations, using infrared images from Spitzer Space Telescope and x-ray images from XMM-Newton of the ˜2 square degree area of the COSMOS field. We first masked all known sources and subtracted model images of the masked x-ray sources’ PSF tails so as to isolate the unresolved cosmic backgrounds. We have considered infrared data from two bands, 3.6 and 4.5 μm, and x-ray data from five bands, [0.3-0.5], [0.5-1], [1-2], [0.5-2], and [2-10] keV. We find strong correlation between the cosmic infrared and cosmic x-ray backgrounds, which suggests an origin in a common population, i.e., stars and/or growing black holes.

  3. 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.

  4. Cosmic background radiation temperature at 2. 64 millimeters

    SciTech Connect

    Crane, P.; Hegyi, D.J.; Kutner, M.L.; Mandolesi, N. Michigan Univ., Ann Arbor Rensselaer Polytechnic Institute, Troy, NY CNR, Istituto di Studio e Tecnologie sulle Radiazzioni Estraterrestri, Bologna )

    1989-11-01

    A precise value for cosmic background radiation (CBR) temperature at 2.64 mm is reported using interstellar CN molecules in absorption in the direction of Zeta Oph. A search for CN emission at 2.64 mm makes it possible to set a strong limit on local excitation sources that could elevate the population of the 2.64 mm rotational states above that expected from the cosmic background radiation. To one standard deviation, observations show that T(loc) is not above 31 mK. A reanalysis of data previously reported has improved the precision of the optical equivalent widths so that this source of uncertainty is now 13.3 mK. Uncertainties in the saturation correction model add to the error budget. The final value for T(CBR) = 2.796(+0.014, -0.039) K. 27 refs.

  5. 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.

  6. Can decaying particle explain cosmic infrared background excess?

    NASA Astrophysics Data System (ADS)

    Kohri, Kazunori; Moroi, Takeo; Nakayama, Kazunori

    2017-09-01

    Recently the CIBER experiment measured the diffuse cosmic infrared background (CIB) flux and claimed an excess compared with integrated emission from galaxies. We show that the CIB spectrum can be fitted by the additional photons produced by the decay of a new particle. However, it also contributes too much to the anisotropy of the CIB, which is in contradiction with the anisotropy measurements by the CIBER and Hubble Space Telescope.

  7. Primary and Secondary Anisotropies of Cosmic Microwave Background

    NASA Technical Reports Server (NTRS)

    Seljak, Uros

    2002-01-01

    The three main topics we proposed to do are linear calculations (continuing development of CMBFAST), nonlinear calculations of gas physics relevant to Cosmic Microwave Background (CMB) (Sunyaev-Zeldovich effect, etc.) and nonlinear effects on CMB due to dark matter (gravitational lensing, etc.). We describe each of these topics, as well as additional topics PI and his group worked on that are related to the topics in the proposal.

  8. The origin of the cosmic X-ray background

    NASA Technical Reports Server (NTRS)

    Shanks, T.; Georgantopoulos, I.; Stewart, G. C.; Pounds, K. A.; Boyle, B. J.; Griffiths, R. E.

    1991-01-01

    A high-resolution image from the Rosat X-ray satellite reveals many faint discrete sources in the 0.1-2-keV energy range. Optical spectroscopy of these sources performed at the Anglo-Australian Telescope shows that many of them are quasars, and the inferred density of quasars on the sky contributes at least 30 percent of the cosmic X-ray background at 1 kev.

  9. Cosmic microwave background measurements can discriminate among inflation models

    SciTech Connect

    Dodelson, S. |

    1997-09-01

    Quantum fluctuations during inflation may be responsible for temperature anisotropies in the cosmic microwave background (CMB). Observations of CMB anisotropies can be used to falsify many currently popular models. In this paper we discuss the prospectus for observations of CMB anisotropies at the accuracy of planned satellite missions to reject currently popular inflation models and to provide some direction for model building. {copyright} {ital 1997} {ital The American Physical Society}

  10. 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.

  11. 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.

  12. 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)

  13. Consistent cosmic microwave background spectra from quantum depletion

    SciTech Connect

    Casadio, Roberto; Orlandi, Alessio; Kühnel, Florian E-mail: florian.kuhnel@fysik.su.se

    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.

  14. 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

    2014-04-04

    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.

  15. 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.

  16. Current Status and Perspectives of Cosmic Microwave Background Observations

    NASA Astrophysics Data System (ADS)

    Bersanelli, Marco; Maino, Davide; Mennella, Aniello

    2004-04-01

    Measurements of the cosmic microwave background (CMB) radiation provide a unique opportunity for a direct study of the primordial cosmic plasma at redshift z ~103. The angular power spectra of temperature and polarisation fluctuations are powerful observational objectives as they encode information on fundamental cosmological parameters and on the physics of the early universe. A large number of increasingly ambitious balloon-borne and ground-based experiments have been carried out following the first detection of CMB anisotropies by COBE-DMR, probing the angular power spectrum up to high multipoles. The recent data from WMAP provide a new major step forward in measurements percision. The ESA mission ``Planck Surveyor'', to be launched in 2007, is the third-generation satellite devoted to CMB imaging. Planck is expected to extract the full cosmological information from temperature anisotropies and to open up new fronteers in the CMB field.

  17. Can one 'weight' the cosmic strings with the microwave background

    NASA Astrophysics Data System (ADS)

    Bouchet, Francois R.

    Estimates of the cosmic microwave background anisotropy that is produced by a network of cosmic strings are presented. String networks were evolved dynamically in a flat matter-era cosmology, by using a code developed to study the relaxation to, and the properties of, the scaling solution. Using a formalism developed by Stebbins (1985) for calculating microwave anisotropy generated gravitationally by moving objects, the temperature patterns produced by these networks are computed. The angular size of the resulting temperature maps depends on the redshift of last scattering but will be in the range 7-40 deg. It is not yet possible to 'weight' the strings, but present experiments already put an interesting upper limit on their mass per unit length.

  18. Detection prospects for the Cosmic Neutrino Background using laser interferometers

    NASA Astrophysics Data System (ADS)

    Domcke, Valerie; Spinrath, Martin

    2017-06-01

    The cosmic neutrino background is a key prediction of Big Bang cosmology which has not been observed yet. The movement of the earth through this neutrino bath creates a force on a pendulum, as if it were exposed to a cosmic wind. We revise here estimates for the resulting pendulum acceleration and compare it to the theoretical sensitivity of an experimental setup where the pendulum position is measured using current laser interferometer technology as employed in gravitational wave detectors. We discuss how a significant improvement of this setup can be envisaged in a micro gravity environment. The proposed setup could also function as a dark matter detector in the sub-MeV range, which currently eludes direct detection constraints.

  19. Cosmology with the cosmic microwave background temperature-polarization correlation

    NASA Astrophysics Data System (ADS)

    Couchot, F.; Henrot-Versillé, S.; Perdereau, O.; Plaszczynski, S.; Rouillé d'Orfeuil, B.; Spinelli, M.; Tristram, M.

    2017-06-01

    We demonstrate that the cosmic microwave background (CMB) temperature-polarization cross-correlation provides accurate and robust constraints on cosmological parameters. We compare them with the results from temperature or polarization and investigate the impact of foregrounds, cosmic variance, and instrumental noise. This analysis makes use of the Planck high-ℓ HiLLiPOP likelihood based on angular power spectra, which takes into account systematics from the instrument and foreground residuals directly modelled using Planck measurements. The temperature-polarization correlation (TE) spectrum is less contaminated by astrophysical emissions than the temperature power spectrum (TT), allowing constraints that are less sensitive to foreground uncertainties to be derived. For ΛCDM parameters, TE gives very competitive results compared to TT. For basic ΛCDM model extensions (such as AL, ∑mν, or Neff), it is still limited by the instrumental noise level in the polarization maps.

  20. Cosmic acceleration and the theory of the microwave background

    NASA Astrophysics Data System (ADS)

    Gold, Benjamin Mark

    2005-06-01

    The increasing precision of cosmological datasets is opening up new opportunities to test predictions from cosmic inflation. In this work I study the impact of high precision constraints on the primordial power spectrum and show how a new generation of observations can provide impressive new tests of the slow-roll inflation paradigm, as well as produce significant discriminating power among different slow-roll models. In particular, I consider next- generation measurements of the Cosmic Microwave Background (CMB) temperature anisotropies and (especially) polarization. I emphasize relationships between the slope of the power spectrum and its first derivative that are nearly universal among existing slow-roll inflationary models, and show how these relationships can be tested on several scales with new observations. Among other things, the results give additional motivation for an all-out effort to measure CMB polarization. While photons continue to travel almost freely during the matter era, changes in the expansion rate due to acceleration at late times can subtly affect their distribution. Such acceleration is posited to be due to the effects of an otherwise unobserved dark energy. Also in this work I discuss several issues that arise when trying to constrain the dark energy equation of state using correlations of the integrated Sachs-Wolfe effect with galaxy counts and lensing of the cosmic microwave background. These techniques are complementary to others such as galaxy shear surveys, and can use data that will already be obtained from currently planned observations. In regimes where cosmic variance and shot noise are the dominant sources of error, constraints could be made on the mean equation of state to within 0.33 and its first derivative to within 1.0. Perhaps more interesting is that the determination of dark energy parameters by these types of experiments depends strongly on the presence or absence of perturbations in the dark energy fluid.

  1. Statistics of Cosmic Microwave Background Radiation with the Cosmic String Model

    NASA Astrophysics Data System (ADS)

    Mähönen, Petri; Hara, Tetsuya; Voll, Toivo; Miyoshi, Shigeru

    We have studied the cosmic microwave background radiation by simulating the cosmic string network induced anisotropies on the sky. The large-angular size simulations are based on the Kaiser-Stebbins effect calculated from full cosmic-string network simulation. The small-angular size simulations are done by Monte-Carlo simulation of perturbations from a time-discretized toy model. We use these results to find the normalization of μ, the string mass per unit length, and compare this result with one needed for large-scale structure formation. We show that the cosmic string scenario is in good agreement with COBE, SK94, and MSAM94 microwave background radiation experiments with reasonable string network parameters. The predicted rms-temperature fluctuations for SK94 and MSAM94 experiments are Δ T/T=1.57×10-5 and Δ T/T=1.62×10-5, respectively, when the string mass density parameter is chosen to be Gμ=1.4×10-6. The possibility of detecting non-Gaussian signals using the present day experiments is also discussed.

  2. The Cosmic Background Radiation circa ν2K

    NASA Astrophysics Data System (ADS)

    Bond, J. Richard; Pogosyan, Dmitry; Prunet, Simon

    We describe the implications of cosmic microwave background (CMB) observations and galaxy and cluster surveys of large scale structure (LSS) for theories of cosmic structure formation, especially emphasizing the recent Boomerang and Maxima CMB balloon experiments. The inflation-based cosmic structure formation paradigm we have been operating with for two decades has never been in better shape. Here we primarily focus on a simplified inflation parameter set, {ωb, ωcdm, Ωtot, ΩΛ, ns, τC, σ8}. Combining all of the current CMB+LSS data points to the remarkable conclusion that the local Hubble patch we can access has little mean curvature (Ωtot = 1.08 +/- 0.06) and the initial fluctuations were nearly scale invariant (ns = 1.03 +/- 0.08), both predictions of (non-baroque) inflation theory. The baryon density is found to be slightly larger than that preferred by independent Big Bang Nucleosynthesis estimates (ωb --- Ωbh2 = 0.030 +/- 0.005 cf. 0.019 +/- 0.002). The CDM density is in the expected range (ωcdm = 0.17+/-0.02). Even stranger is the CMB+LSS evidence that the density of the universe is dominated by unclustered energy akin to the cosmological constant (ΩΛ = 0.66 +/- 0.06), at the same level as that inferred from high redshift supernova observations. We also sketch the CMB+LSS implications for massive neutrinos.

  3. Cosmic microwave background radiation of black hole universe

    NASA Astrophysics Data System (ADS)

    Zhang, T. X.

    2010-11-01

    Modifying slightly the big bang theory, the author has recently developed a new cosmological model called black hole universe. This new cosmological model is consistent with the Mach principle, Einsteinian general theory of relativity, and observations of the universe. The origin, structure, evolution, and expansion of the black hole universe have been presented in the recent sequence of American Astronomical Society (AAS) meetings and published recently in a scientific journal: Progress in Physics. This paper explains the observed 2.725 K cosmic microwave background radiation of the black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present universe with hundred billion-trillions of solar masses. According to the black hole universe model, the observed cosmic microwave background radiation can be explained as the black body radiation of the black hole universe, which can be considered as an ideal black body. When a hot and dense star-like black hole accretes its ambient materials and merges with other black holes, it expands and cools down. A governing equation that expresses the possible thermal history of the black hole universe is derived from the Planck law of black body radiation and radiation energy conservation. The result obtained by solving the governing equation indicates that the radiation temperature of the present universe can be ˜2.725 K if the universe originated from a hot star-like black hole, and is therefore consistent with the observation of the cosmic microwave background radiation. A smaller or younger black hole universe usually cools down faster. The characteristics of the original star-like or supermassive black hole are not critical to the physical properties of the black hole universe at present, because matter and radiation are mainly from the outside space, i.e., the mother universe.

  4. Zonal modes of Cosmic Microwave Background temperature maps

    NASA Astrophysics Data System (ADS)

    Short, Jo; Coles, Peter

    2010-02-01

    All-sky maps of the cosmic microwave background temperature fluctuations are usually represented by a spherical harmonic decomposition, involving modes labelled by their degree l and order m (where -l <= m <= +l). The zonal modes (i.e. those with m = 0) are of particular interest because they vary only with galactic latitude; any anomalous behaviour in them might therefore be an indication of erroneous foreground substraction. We perform a simple statistical analysis of the modes with low l for sky maps derived via different cleaning procedures from the Wilkinson Microwave Anisotropy Probe, and show that the zonal modes provide a useful diagnostic of possible systematics.

  5. 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.

  6. Footprints of Loop I on Cosmic Microwave Background maps

    SciTech Connect

    Hausegger, Sebastian von; Liu, Hao; Sarkar, Subir; Mertsch, Philipp E-mail: liuhao@nbi.dk E-mail: s.sarkar@physics.ox.ac.uk

    2016-03-01

    Cosmology has made enormous progress through studies of the cosmic microwave background, however the subtle signals being now sought such as B-mode polarisation due to primordial gravitational waves are increasingly hard to disentangle from residual Galactic foregrounds in the derived CMB maps. We revisit our finding that on large angular scales there are traces of the nearby old supernova remnant Loop I in the WMAP 9-year map of the CMB and confirm this with the new SMICA map from the Planck satellite.

  7. The submillimeter spectrum of the cosmic background radiation

    NASA Technical Reports Server (NTRS)

    Matsumoto, T.; Hayakawa, S.; Matsuo, H.; Murakami, H.; Sato, S.

    1988-01-01

    The diffuse brightness of the sky has been measured in six submillimeter passbands, using a rocket-borne, liquid helium-cooled, absolute radiometer. The flux measured at 1160 microns is in good agreement with the average of longer wavelength measurements of the temperature of the cosmic background radiation. The fluxes measured at 709 microns and 481 microns show a rapid decrease toward shorter wavelength, but correspond to significantly higher temperatures. No local source of this excess flux has been identified. The spectrum of the excess significantly constrains cosmological models. Data at 262, 137, and 102 microns are consistent with emission from interstellar dust.

  8. 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.

  9. 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.

  10. 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.

  11. The cosmic history of the X-ray background.

    PubMed

    Barger, Amy J

    2005-03-15

    The Chandra and XMM-Newton X-ray observatories have detected obscured active galactic nuclei (AGN) and almost fully resolved the X-ray background into discrete sources. Ground-based observations of the X-ray sources enable the reconstruction of the history of supermassive black hole accretion from the earliest times to the present. A dramatic cosmic downsizing of AGN luminosities is seen at recent times. Correspondingly, the production rate of the AGN radiation drops rapidly, and the dominant period of supermassive black hole production is seen to be at redshifts near z = 1.

  12. The cosmic microwave background in a causal set universe

    SciTech Connect

    Zuntz, Joe

    2008-02-15

    We discuss cosmic microwave background constraints on the causal set theory of quantum gravity, which has made testable predictions about the nature of dark energy. We flesh out previously discussed heuristic constraints by showing how the power spectrum of causal set dark energy fluctuations can be found from the overlap volumes of past light cones of points in the universe. Using a modified Boltzmann code we put constraints on the single parameter of the theory that are somewhat stronger than previous ones. We conclude that causal set theory cannot explain late-time acceleration without radical alterations to general relativity.

  13. 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.

  14. 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.

  15. Spectrum of the cosmic background radiation at millimeter wavelengths

    SciTech Connect

    Peterson, J.B.; Richards, P.L.; Timusk, T.

    1985-07-15

    We have measured the spectrum of the cosmic background radiation in five frequency bands extending from 2.3 to 11.0 cm/sup -1/ with a balloon-borne liquid-helium cooled pho- tometer. The photometer compares the flux from the sky to the flux from an internal blackbody at 3.2 K. All five measurements are consistent with temperatures in the range 2.78 +- 0.11 K, which is in good agreement with temperatures measured at lower frequencies. We find no significant deviation from a thermal spectrum.

  16. New Measurements of the Cosmic Background Radiation Spectrum

    SciTech Connect

    Smoot, G.F.; De Amici, G.; Levin, S.; Witebsky, C.

    1984-12-01

    We have continued our program to measure the long-wavelength spectrum of the cosmic background radiation. Our previous observations were at five wavelengths--0.33, 0.9, 3.0, 6.3, and 12.0 cm--and had a weighted average value of 2.73 {+-} 0.05 K and deviated from a Planckian spectrum by less than 6%. In August 1984, we repeated our observations at 3.0, 0.9, and 0.33 cm and made new observations with a radiometer tunable from 1.7 to 15 cm. Preliminary analysis indicate that the new data are consistent with our previous results.

  17. 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.

  18. Prospectives on Direct Detection of the Cosmic Neutrino Background

    NASA Astrophysics Data System (ADS)

    Li, Yu-Feng

    2017-09-01

    The cosmic neutrino background (CνB) is a fundamental prediction of the hot Big Bang cosmology. Although cosmological observations provide indirect evidence for the existence of the CνB, we still lack a direct detection in a laboratory. In this work we present the current possible detection methods of the CνB. The method of CνB captures on the radioactive decaying nuclei is particularly emphasized in light of the PTOLEMY project. We stress that such direct measurements might not be hopeless in the long term.

  19. 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

  20. Peak-peak correlations in the cosmic background radiation from cosmic strings

    NASA Astrophysics Data System (ADS)

    Movahed, M. Sadegh; Javanmardi, B.; Sheth, Ravi K.

    2013-10-01

    We examine the two-point correlation function of local maxima in temperature fluctuations at the last scattering surface when this stochastic field is modified by the additional fluctuations produced by straight cosmic strings via the Kaiser-Stebbins effect. We demonstrate that one can detect the imprint of cosmic strings with tension Gμ ≳ 1.2 × 10-8 on noiseless 1 arcmin resolution cosmic microwave background (CMB) maps at 95 per cent confidence interval. Including the effects of foregrounds and anticipated systematic errors increases the lower bound to Gμ ≳ 9.0 × 10-8 at 2σ confidence level. Smearing by beams of the order of 4 arcmin degrades the bound further to Gμ ≳ 1.6 × 10-7. Our results indicate that two-point statistics are more powerful than one-point statistics (e.g. number counts) for identifying the non-Gaussianity in the CMB due to straight cosmic strings.

  1. 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.

  2. 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

  3. Cosmic infrared background measurements and star formation history from Planck

    NASA Astrophysics Data System (ADS)

    Serra, Paolo; Serra

    2014-05-01

    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. 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 interpretation based on the halo model is able to associate star-forming galaxies with dark matter halos and their subhalos, using a parametrized relation between the dust-processed infrared luminosity and (sub-)halo mass, and it allows to 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(M eff/M ⊙) = 12.6 and that CIB galaxies have warmer temperatures as redshift increases.

  4. 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.

  5. Radiation in the Einstein universe and the cosmic background

    SciTech Connect

    Segal, I.E.

    1983-11-15

    It is shown that the cosmic background radiation is not at all uniquely or scientifically relatively economically indicative of a ''big bang.'' Specifically, essentially any temporally homogeneous theory in the Einstein universe is consistent with the existence of a cosmic background radiation (CBR) conforming to the Planck law; in particular, the chronometric cosmology is such. It is noted that the Einstein universe appears particularly natural as a habitat for photons by virtue of the absence of infrared divergences and of the absolute convergence of the trace for associated Gibbs-state density matrices. These features are connected with the closed character of space in the Einstein universe, and facilitate the use of the latter in modeling local phenomena, in place of Minkowski space with periodic boundary conditions or the like, with minimal loss of covariance or effect on the wave functions. In particular, the Einstein universe may be used in the analysis of the perturbation of a Planck-law spectrum due to a local nonvanishing isotropic angular momentum of the CBR, of whatever origin. The estimated distortion of the spectrum due to such a kinematically admissible effect is in very good agreement with that observed by Woody and Richards, which is opposite in direction to those earlier predicted by big-bang theories. The theoretical analysis involves a preliminary treatment of equilibria of linear quantum fields with supplementary quasilinear constraints.

  6. Absolute measurements of the cosmic microwave background from Amundsen-Scott South Pole Station

    SciTech Connect

    Bersanelli, S.; Bonelli, G.; Sironi, G. ); Levin, S. ); Smoot, G.F.; Bensadoun, M.; De Amici, G.; Limon, M.; Vinje, W. )

    1993-01-01

    Observations of the cosmic microwave background play a central role in modern cosmology. The existence of the CMB as a remanent of the early Universe has constituted a pillar for the Big Bang scenario. The recent cosmic background explorer differential microwave radiometer results have provided further support to the generally accepted standard model by detecting for the first time primordial fluctuations in the CMB field at the limits expected by structure formation theories. An international program of ground-based absoluted measurements of the CMB at the centimeter and multicentimeter wavelengths was initiated in 1982. This paper reports results at the South Pole, one of a few areas of low-background environments. 12 refs., 2 tabs.

  7. 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.

  8. 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.

  9. Multiple cosmic collisions and the microwave background power spectrum

    NASA Astrophysics Data System (ADS)

    Aguirre, Anthony; Kozaczuk, Jonathan

    2013-01-01

    Collisions between cosmic bubbles of different vacua are a generic feature of false vacuum eternal inflation scenarios. While previous studies have focused on the consequences of a single collision event in an observer’s past, we begin here an investigation of the more general scenario allowing for many “mild” collisions intersecting our past light cone (and one another). We discuss the general features of multiple collision scenarios and consider their impact on the cosmic microwave background (CMB) temperature power spectrum, treating the collisions perturbatively. In a large class of models, one can approximate a multiple collision scenario as a superposition of individual collision events governed by nearly isotropic and scale-invariant distributions, most appearing to take up less than half of the sky. In this case, the shape of the expected CMB temperature spectrum maintains statistical isotropy and typically features a dramatic increase in power in the low multipoles relative to that of the best-fit ΛCDM model, which is in tension particularly with the observed quadrupole. We argue that this predicted spectrum is largely model independent and can be used to outline features of the underlying statistical distributions of colliding bubbles consistent with CMB temperature measurements.

  10. Cosmic microwave background trispectrum and primordial magnetic field limits.

    PubMed

    Trivedi, Pranjal; Seshadri, T R; Subramanian, Kandaswamy

    2012-06-08

    Primordial magnetic fields will generate non-gaussian signals in the cosmic microwave background (CMB) as magnetic stresses and the temperature anisotropy they induce depend quadratically on the magnetic field. We compute a new measure of magnetic non-gaussianity, the CMB trispectrum, on large angular scales, sourced via the Sachs-Wolfe effect. The trispectra induced by magnetic energy density and by magnetic scalar anisotropic stress are found to have typical magnitudes of approximately a few times 10(-29) and 10(-19), respectively. Observational limits on CMB non-gaussianity from WMAP data allow us to conservatively set upper limits of a nG, and plausibly sub-nG, on the present value of the primordial cosmic magnetic field. This represents the tightest limit so far on the strength of primordial magnetic fields, on Mpc scales, and is better than limits from the CMB bispectrum and all modes in the CMB power spectrum. Thus, the CMB trispectrum is a new and more sensitive probe of primordial magnetic fields on large scales.

  11. 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

  12. Dipole modulation of cosmic microwave background temperature and polarization

    SciTech Connect

    Ghosh, Shamik; Kothari, Rahul; Jain, Pankaj; Rath, Pranati K. E-mail: rahulko@iitk.ac.in E-mail: pranati@iopb.res.in

    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.

  13. New measurements of the spectrum of the cosmic microwave background

    SciTech Connect

    Peterson, J.B.; Richards, P.L.; Bonomo, J.L.; Timusk, T.

    1984-06-01

    Accurate measurements of the spectrum of the cosmic microwave background (CMB) can provide useful tests of cosmological theories. The data set existing in 1982 has been summarized on a number of occasions and is shown. To first approximation the CMB is characterized by a single temperature and thus has a blackbody spectrum over the frequency range from 0.02 to 24 cm/sup -1/. The error limits given for these experiments are dominated by systematic errors and are often very subjective. Consequently, it is not clear how to analyze the data set in a valid way. The general impression, however, is of a scatter in the high frequency data that is somewhat larger than would be expected from the given error limits. We have designed a new apparatus to measure the spectrum of the CMB in the frequency range from 3 to 10 cm/sup -1/. 13 references, 5 figures.

  14. 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.

  15. 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.

  16. 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.

  17. Detecting Patchy Reionization in the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Smith, Kendrick M.; Ferraro, Simone

    2017-07-01

    Upcoming cosmic microwave background (CMB) experiments will measure temperature fluctuations on small angular scales with unprecedented precision. Small-scale CMB fluctuations are a mixture of late-time effects: gravitational lensing, Doppler shifting of CMB photons by moving electrons [the kinematic Sunyaev-Zel'dovich (KSZ) effect], and residual foregrounds. We propose a new statistic which separates the KSZ signal from the others, and also allows the KSZ signal to be decomposed in redshift bins. The decomposition extends to high redshift and does not require external data sets such as galaxy surveys. In particular, the high-redshift signal from patchy reionization can be cleanly isolated, enabling future CMB experiments to make high-significance and qualitatively new measurements of the reionization era.

  18. New 33 GHz measurements of the cosmic background radiation intensity

    SciTech Connect

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

    1985-11-15

    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 at 68% of confidence limits, is in very good agreement both with those previously published and those reported by our collaborators.

  19. First Cosmic Microwave Background Anisotropy Results from DASI

    NASA Astrophysics Data System (ADS)

    Carlstrom, J. E.

    2001-04-01

    The Degree Angular Scale Interferometer (DASI) is a 13-element array of horns operating at 26 - 36 GHz designed to determine the angular power spectrum of the Cosmic Microwave Background over a broad range of multipoles (140 to 900), and to produce high signal to noise images. The range of multipoles spans the first three acoustic peaks in the standard cosmological model. DASI was deployed successfully at the Amundsen-Scott South Pole station during the 1999/2000 Austral summer and collected high quality data throughout the Austral Winter. After a brief overview of the instrument and its capabilities, we will present the results of the analysis of the first year of DASI measurements and the constraints they place on cosmological parameters.

  20. South Pole submillimeter isotropy measurements of the cosmic microwave background

    SciTech Connect

    Dragovan, M. ); Platt, S.R.; Pernic, R.J. ); Stark, A.A. )

    1990-01-15

    Observations were made from the United States Amundsen-Scott South Pole Station during the austral summer of 1988--89 to search for spatial anisotropy in the submillimeter Cosmic Microwave Background. Three 30{prime}{times}30{prime} regions of the sky were observed at 350 {mu}m, 450 {mu}m, and 600 {mu}m with the University of Chicago 32-Channel Submillimeter Photometer and a 1.2-meter off-axis parabolic telescope, designed and constructed at AT T Bell Laboratories. Reimaging optics gave each of the 32 bolometers in the array a 5-arc minute field of view. The search is sensitive to fluctuations on all angular scales between 5- and 30-arc minutes.

  1. Local Signal Impedes the Definition of the Cosmic Infrared Background

    NASA Astrophysics Data System (ADS)

    Kelsall, Thomas

    2010-01-01

    It was noted (ApJ 508, 44, 1998) when developing a COBE/DIRBE-data-based model for the infrared (IR) signal from the interplanetary dust cloud (IPD) that there were clear evidences of unexpected time-variable wavelength-dependent signals in all the ten DIRBE bands (1.2 to 240 μm). The amplitudes of these signals range in magnitude from the order of one-half to a few percent of the respective-wavelength IPD signal. This presentation provides selected details on the nature of these signals as regards their wavelength-dependent periodicities, time-variable amplitudes, and complex spatial configurations. Particular attention is devoted to describing the consequences imposed by these signals which impede the observational determination of and/or the setting of limits on the cosmic IR background.

  2. 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).

  3. Large-angular-scale anisotropy in the cosmic background radiation

    NASA Astrophysics Data System (ADS)

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

    1981-03-01

    Results of an extended series of airborne measurements of large-angular-scale anisotropy in the 3-K cosmic background radiation are reported. A dual-antenna microwave radiometer operating at 33 GHz flown aboard a U-2 aircraft to 20-km altitude on 11 flights between December 1976 and May 1978 measured differential intensity between pairs of directions distributed over most of the Northern Hemisphere. 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 fitted by a first order spherical harmonic of amplitude 3.6 + or - 0.5 mK, corresponding to a velocity of 360 + or - 50 km/s toward the direction 11.2 + or - 0.5 hours of right ascension and 19 deg + or - 8 deg declination.

  4. 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.

  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. Development of MMIC receivers for cosmic microwave background interferometry

    NASA Astrophysics Data System (ADS)

    Sieth, Matthew; Lau, Judy M.; Voll, Patricia; Church, Sarah; Kangaslahti, Pekka; Samoska, Lorene; Soria, Mary; Gaier, Todd; Van Winkle, Dan; Neilson, Jeffrey; Tantawi, Sami; Cleary, Kieran; Readhead, Anthony C. S.

    2010-07-01

    We report on the development of some of the key technologies that will be needed for a large-format Cosmic Microwave Background (CMB) interferometer with many hundreds of wideband W-band (75-110 GHz) receivers. A scalable threebaseline prototype interferometer is being assembled as a technology demonstration for a future ground- or space-based instrument. Each of the prototype heterodyne receivers integrates two InPMonolithic Microwave Integrated Circuit (MMIC) low-noise amplifiers, a coupled-line bandpass filter, a subharmonic balanced diode mixer, and a 90° local oscillator phase switch into a single compact module that is suitable for mass production. Room temperature measurements indicate bandaveraged receiver noise temperatures of 500 K from 85-100 GHz. Cryogenic receiver noise temperatures are expected to be around 50 K.

  7. The phenomenological status of late time phase transition models after cosmic background radiation anisotropy measurements

    NASA Technical Reports Server (NTRS)

    Luo, Xiaochun; Schramm, David N.

    1994-01-01

    Some relatively model-independent results for structure formation via late time phase transitions (LTPT) are discussed. In particular, generic LTPT power spectra are presented. The implication of the recent Cosmic Background Explorer (COBE) detection of the cosmic background radiation (CBR) anisotropy at large angular scales (greater than or approximately equal to 7 deg) and the tight upper limits from small angular scales (approximately 1 deg) to LTPT models are discussed. Special attention is focused on the observational constraints and possible non-Gaussian signatures of CBR temperature anisotropies from LTPT and other non-Gaussian models. It is shown that while LTPT have been seriously constrained by the recent data, viable models do remain which provide more power on the 100-200 Mpc scales than do more traditional primordial Gaussian density fluctuation models. Tests for such models are presented, including possible anisotropies on angular scales less than 8 min.

  8. 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).

  9. 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.

  10. Exploring the Cosmic Context of Earth

    NASA Astrophysics Data System (ADS)

    Dominik, Martin

    2014-04-01

    Studying the amazingly diverse planet zoo provides us with unprecedented opportunities for understanding planet Earth and ultimately ourselves. An assessment of a planet's ``habitability'' reflects our Earth-centric prejudice and can serve to prioritise targets to actually search for signatures of life similar to ours. The probability for life beyond Earth to exist however remains unknown, and studies on habitability or statistics of planetary systems do not change this. But we can leave speculation behind, and embark on a journey of exploration. A sample of detected cosmic habitats would provide us with insight on the conditions for life to emerge, develop, and sustain, but disentangling the biota fraction from the duration of the biotic era would depend particularly on our knowledge about the dynamics of planetary systems. Apart from the fact that planets usually do not come alone, we also must not forget that the minor bodies in the Solar system vastly outnumber the planets. A focus on just what we might consider ``habitable'' planets is too narrow to understand their formation and evolution. While uniqueness prevents understanding, we need to investigate the context and embrace diversity. A comprehensive picture of planet populations can only arise by exploiting a variety of different detection techniques, where not only Kepler but also gravitational microlensing can now enter hitherto uncharted territory below the mass or size of the Earth. There is actually no shortage of planets, the Milky Way alone may host hundreds of billions, and so far we have found only about 1000.

  11. The cosmic infrared background experiment (CIBER): instrumentation and first results

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    Ultraviolet emission from the first generation of stars in the Universe ionized the intergalactic medium in a process which was completed by z ~ 6; the wavelength of these photons has been redshifted by (1 + z) into the near infrared today and can be measured using instruments situated above the Earth's atmosphere. First flying in February 2009, the Cosmic Infrared Background ExpeRiment (CIBER) comprises four instruments housed in a single reusable sounding rocket borne payload. CIBER will measure spatial anisotropies in the extragalactic IR background caused by cosmological structure from the epoch of reionization using two broadband imaging instruments, make a detailed characterization of the spectral shape of the IR background using a low resolution spectrometer, and measure the absolute brightness of the Zodiacal light foreground with a high resolution spectrometer in each of our six science fields. The scientific motivation for CIBER and details of its first and second flight instrumentation will be discussed. First flight results on the color of the zodiacal light around 1 μm and plans for the future will also be presented.

  12. Cosmic microwave background limits on accreting primordial black holes

    NASA Astrophysics Data System (ADS)

    Ali-Haïmoud, Yacine; Kamionkowski, Marc

    2017-02-01

    Interest in the idea that primordial black holes (PBHs) might comprise some or all of the dark matter has recently been rekindled following LIGO's first direct detection of a binary-black-hole merger. Here we revisit the effect of accreting PBHs on the cosmic microwave background (CMB) frequency spectrum and the angular temperature and polarization power spectra. We compute the accretion rate and luminosity of PBHs, accounting for their suppression by Compton drag and Compton cooling by CMB photons. We estimate the gas temperature near the Schwarzschild radius and, hence, the free-free luminosity, accounting for the cooling resulting from collisional ionization when the background gas is mostly neutral. We account approximately for the velocities of PBHs with respect to the background gas. We provide a simple analytic estimate of the efficiency of energy deposition in the plasma. We find that the spectral distortions generated by accreting PBHs are too small to be detected by FIRAS, as well as by future experiments now being considered. We analyze Planck CMB temperature and polarization data and find, under our most conservative hypotheses, and at the order-of-magnitude level, that they rule out PBHs with masses ≳1 02 M⊙ as the dominant component of dark matter.

  13. Dark energy records in lensed cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Acquaviva, Viviana; Baccigalupi, Carlo

    2006-11-01

    We consider the weak lensing effect induced by linear cosmological perturbations on the cosmic microwave background (CMB) polarization anisotropies. We find that the amplitude of the lensing peak in the BB mode power spectrum is a faithful tracer of the dark energy dynamics at the onset of cosmic acceleration. This is due to two reasons. First, the lensing power is nonzero only at intermediate redshifts between the observer and the source, keeping record of the linear perturbation growth rate at the corresponding epoch. Second, the BB lensing signal is expected to dominate over the other sources. The lensing distortion on the TT and EE spectra do exhibit a similar dependence on the dark energy dynamics, although those are dominated by primary anisotropies. We investigate and quantify the effect by means of exact tracking quintessence models, as well as parameterizing the dark energy equation of state in terms of the present value (w0) and its asymptotic value in the past (w∞); in the interval allowed by the present constraints on dark energy, the variation of w∞ induces a significant change in the BB mode lensing amplitude. A Fisher matrix analysis, under conservative assumptions concerning the increase of the sample variance due to the lensing non-Gaussian statistics, shows that a precision of order 10% on both w0 and w∞ is achievable by the future experiments probing a large sky area with angular resolution and sensitivity appropriate to detect the lensing effect on the CMB angular power spectrum; the forecast precision reaches a few percent for highly dynamic models whose dark energy abundance at the epoch when lensing is most effective is sensibly larger than the present one, i.e. for w∞≳-0.5. These results show that the CMB can probe the differential redshift behavior of the dark energy equation of state, beyond its average.

  14. 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.

  15. 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.

  16. Minimal cosmic background fluctuations implied by streaming motions

    SciTech Connect

    Juszkiewicz, R.; Gorski, K.; Silk, J.

    1987-12-01

    The minimal cosmic background radiation (CBR) anisotropy implied by the presence of peculiar motions of a given amplitude on some specified scale is calculated using a new, power spectrum-independent approach. If the tentative evidence for deviations from the Hubble flow of magnitude delta V/V roughly 0.1 at V roughly 5000 km/s is confirmed, microwave background fluctuations with a coherence scale of about 2 deg and dispersion delta T/T greater than 10 to the -5th are predicted. It is found that the existing upper limits on delta T/T are not inconsistent with v(r) = 500 km/s at r = 50/h Mpc. A reduction of the observational limits on the CBR anisotropy below the authors' minimal predictions for delta T/T would challenge the current interpretation of measurements of deviations from the Hubble flow. Gravitational instability without reheating as a mechanism for generation of the large-scale structure of the universe would be in severe difficulty. 38 references.

  17. Minimal cosmic background fluctuations implied by streaming motions

    NASA Technical Reports Server (NTRS)

    Juszkiewicz, Roman; Gorski, Krzysztof; Silk, Joseph

    1987-01-01

    The minimal cosmic background radiation (CBR) anisotropy implied by the presence of peculiar motions of a given amplitude on some specified scale is calculated using a new, power spectrum-independent approach. If the tentative evidence for deviations from the Hubble flow of magnitude delta V/V roughly 0.1 at V roughly 5000 km/s is confirmed, microwave background fluctuations with a coherence scale of about 2 deg and dispersion delta T/T greater than 10 to the -5th are predicted. It is found that the existing upper limits on delta T/T are not inconsistent with v(r) = 500 km/s at r = 50/h Mpc. A reduction of the observational limits on the CBR anisotropy below the authors' minimal predictions for delta T/T would challenge the current interpretation of measurements of deviations from the Hubble flow. Gravitational instability without reheating as a mechanism for generation of the large-scale structure of the universe would be in severe difficulty.

  18. 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.

  19. Minimal cosmic background fluctuations implied by streaming motions

    NASA Technical Reports Server (NTRS)

    Juszkiewicz, Roman; Gorski, Krzysztof; Silk, Joseph

    1987-01-01

    The minimal cosmic background radiation (CBR) anisotropy implied by the presence of peculiar motions of a given amplitude on some specified scale is calculated using a new, power spectrum-independent approach. If the tentative evidence for deviations from the Hubble flow of magnitude delta V/V roughly 0.1 at V roughly 5000 km/s is confirmed, microwave background fluctuations with a coherence scale of about 2 deg and dispersion delta T/T greater than 10 to the -5th are predicted. It is found that the existing upper limits on delta T/T are not inconsistent with v(r) = 500 km/s at r = 50/h Mpc. A reduction of the observational limits on the CBR anisotropy below the authors' minimal predictions for delta T/T would challenge the current interpretation of measurements of deviations from the Hubble flow. Gravitational instability without reheating as a mechanism for generation of the large-scale structure of the universe would be in severe difficulty.

  20. 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.

  1. Radiometer system to map the cosmic background radiation

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    A 33-GHz airborne radiometer system has been developed 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 deg apart in the sky. In 40 min of observing, the radiometer can measure the anisotropy of the microwave background with an accuracy of plus or minus 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 deg, 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, Calif.

  2. Detection of polarization in the cosmic microwave background using DASI

    NASA Astrophysics Data System (ADS)

    Kovac, John M.

    2004-06-01

    The past several years have seen the emergence of a new standard cosmological model in which small temperature differences in the cosmic microwave background (CMB) on degree angular scales are understood to arise from acoustic oscillations in the hot plasma of the early universe sourced by primordial adiabatic density fluctuations. In 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. Given knowledge of the temperature angular power spectrum, this theoretical framework yields a prediction for the level of the CMB polarization with essentially no free parameters. A determination of the CMB polarization would therefore provide a critical test of the underlying theoretical framework of this standard model. In this thesis, we report the detection of polarized anisotropy in the Cosmic Microwave Background radiation with the Degree Angular Scale Interferometer (DASI), located at the Amundsen-Scott South Pole research station. Observations in all four Stokes parameters were obtained within two 3°4 FWHM fields separated by one hour in Right Ascension. The fields were selected from the subset of fields observed with DASI in 2000 in which no point sources were detected and are located in regions of low Galactic synchrotron and dust emission. The temperature angular power spectrum is consistent with previous measurements and its measured frequency spectral index is -0.01 (-0.16 to 0.14 at 68% confidence), where zero corresponds to a 2.73 K Planck spectrum. The power spectrum of the detected polarization is consistent with theoretical predictions based on the interpretation of CMB anisotropy as arising from primordial scalar adiabatic fluctuations. Specifically, E-mode polarization is detected at high confidence (4.9σ). Assuming a shape for the power spectrum consistent with previous temperature measurements, the level found for the E- mode polarization

  3. An investigation of the cosmic diffuse X-ray background

    NASA Astrophysics Data System (ADS)

    John, Tomykkutty Velliyedathu

    2016-03-01

    The cosmic diffuse X-ray background (CXB), which is only second to the cosmic microwave background (CMB) in prominence, has challenged astrophysicists ever since its serendipitous discovery in 1962. In the past five decades, we have made considerable progress unraveling its mysterious origins. Nevertheless, precise identification of its various components and their individual contributions still remains a puzzling task. The bulk of the XRB comes from the integrated flux of the most luminous astronomical objects- Active Galactic Nuclei (AGN)- as well as the emission from starburst and normal galaxies and can account for most of the emission above 1 keV. In the energy range below 1 keV, several components can be identified besides the dominant extragalactic component. While two thermal components, one at about one million K and the other at about 2.3 million K adequately account for the emission from hot gas in collisional ionization equilibrium, solar wind charge exchange (SWCX) makes a substantial contribution to the SXRB. One of the biggest challenges is to separate the contributions of individual components. This is made difficult by the fact that the spectral structure of all the Galactic components is similar. Shadow experiments have been used to discriminate the various constituents; however, these have only limited use owing to their dependence on estimates of cloud parameters. The best way to make reliable inferences on the contributions of DXB components is to apply good models to valid data with high statistics. With this in mind, for this work, we selected high quality data, from the well-surveyed sky direction- the Chandra Deep Field South (CDF-S)- with 4 Ms of observing time, analyzed them and using several models, derived the important parameters for the various DXB constituents obtaining very good constraints. In addition, we used the same data, spread over a period of nine years, to make a systematic analysis of the temporal variation of heliospheric

  4. Cosmic calibration: Constraints from the matter power spectrum and the cosmic microwave background

    SciTech Connect

    Habib, Salman; Heitmann, Katrin; Higdon, David; Williams, Brian; Nakhleh, Charles

    2007-10-15

    Several cosmological measurements have attained significant levels of maturity and accuracy over the past decade. Continuing this trend, future observations promise measurements of the cosmic mass distribution at an accuracy level of 1% out to spatial scales with k{approx}10h Mpc{sup -1} and even smaller, entering highly nonlinear regimes of gravitational instability. In order to interpret these observations and extract useful cosmological information from them, such as the equation of state of dark energy, very costly high precision, multiphysics simulations must be performed. We have recently implemented a new statistical framework with the aim of obtaining accurate parameter constraints from combining observations with a limited number of simulations. The key idea is the replacement of the full simulator by a fast emulator with controlled error bounds. In this paper, we provide a detailed description of the methodology and extend the framework to include joint analysis of cosmic microwave background and large-scale structure measurements. Our framework is especially well suited for upcoming large-scale structure probes of dark energy such as baryon acoustic oscillations and, especially, weak lensing, where percent level accuracy on nonlinear scales is needed.

  5. 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.

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

    PubMed

    Mukherjee, Suvodip; Souradeep, Tarun

    2016-06-03

    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.

  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. Impact of polarization on the intrinsic cosmic microwave background bispectrum

    NASA Astrophysics Data System (ADS)

    Pettinari, Guido W.; Fidler, Christian; Crittenden, Robert; Koyama, Kazuya; Lewis, Antony; Wands, David

    2014-11-01

    We compute the cosmic microwave background (CMB) bispectrum induced by the evolution of the primordial density perturbations, including for the first time both temperature and polarization using a second-order Boltzmann code. We show that including polarization can increase the signal-to-noise by a factor 4 with respect to temperature alone. We find the expected signal-to-noise for this intrinsic bispectrum of S /N =3.8 ,2.9 ,1.6 and 0.5 for an ideal experiment with an angular resolution of ℓmax=3000 , the proposed CMB surveys PRISM and COrE, and Planck's polarized data, respectively; the bulk of this signal comes from E -mode polarization and from squeezed configurations. We discuss how CMB lensing is expected to reduce these estimates as it suppresses the bispectrum for squeezed configurations and contributes to the noise in the estimator. We find that the presence of the intrinsic bispectrum will bias a measurement of primordial non-Gaussianity of local type by fNLintr=0.66 for an ideal experiment with ℓmax=3000 . Finally, we verify the robustness of our results by recovering the analytic approximation for the squeezed-limit bispectrum in the general polarized case.

  9. Non-Gaussian spectra in cosmic microwave background temperature anisotropies

    NASA Astrophysics Data System (ADS)

    Ferreira, Pedro G.; Magueijo, João

    1997-03-01

    Gaussian cosmic microwave background skies are fully specified by the power spectrum. The conventional method of characterizing non-Gaussian skies is to evaluate higher order moments, the n-point functions, and their Fourier transforms. We argue that this method is inefficient, due to the redundancy of information existing in the complete set of moments. In this paper we propose a set of new statistics or non-Gaussian spectra to be extracted out of the angular distribution of the Fourier transform of the temperature anisotropies in the small field limit. These statistics complement the power spectrum and act as localization, shape, and connectedness statistics. They quantify the generic non-Gaussian structure, and may be used in more general image-processing tasks. We concentrate on a subset of these statistics and argue that while they carry no information in Gaussian theories, they may be the best arena for making predictions in some non-Gaussian theories. As examples of applications we consider superposed Gaussian and non-Gaussian signals, such as point sources in Gaussian theories or the realistic Kaiser-Stebbins effect. We show that in these theories non-Gaussianity is only present in a ring in Fourier space, which is best isolated in our formalism. Subtle but strongly non-Gaussian theories are also written down for which only non-Gaussian spectra may reveal non-Gaussianity.

  10. Moving gravitational lenses: imprints on the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Aghanim, N.; Prunet, S.; Forni, O.; Bouchet, F. R.

    1998-06-01

    With the new generation of instruments for Cosmic Microwave Background (CMB) observations aiming at an accuracy level of a few percent in the measurement of the angular power spectrum of the anisotropies, the study of the contributions due to secondary effects has gained impetus. Furthermore, a reinvestigation of the main secondary effects is crucial in order to predict and quantify their effects on the CMB and the errors that they induce in the measurements. In this paper, we investigate the contribution, to the CMB, of secondary anisotropies induced by the transverse motions of clusters of galaxies. This effect is similar to the Kaiser-Stebbins effect. In order to address this problem, we model the gravitational potential well of an individual structure using the Navarro, Frenk & White profile. We generalise the effect of one structure to a population of objects predicted using the Press-Schechter formalism. We simulate maps of these secondary fluctuations, compute the angular power spectrum and derive the average contributions for three cosmological models. We then investigate a simple method to separate this new contribution from the primary anisotropies and from the main secondary effect, the Sunyaev-Zel'dovich kinetic effect from the lensing clusters.

  11. 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.

  12. 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.

  13. B2FH, the Cosmic Microwave Background and Cosmology*

    NASA Astrophysics Data System (ADS)

    Burbidge, G.

    In this talk I shall start by describing how we set about and carried out the work that led to the publication of Burbidge et al. (1957, hereafter B2FH). I then shall try and relate this work and the circumstances that surrounded it to the larger problem of the origin and formation of the universe. Here it is necessary to look back at the way that ideas developed and how, in many situations, astronomers went astray. Of course this is a personal view, though I very strongly believe that if he were still here, it is the approach that Fred Hoyle would take. I start by describing the problems originally encountered by Gamow and his associates in trying to decide where the helium was made. This leads me to a modern discussion of the origin of 2D, 3He, 4He and 7Li, originally described by B2FH as due to the x-process. While it is generally argued, following Gamow, Alpher, and Herman, that these isotopes were synthesised in a big bang I shall show that it is equally likely that these isotopes were made in active galactic nuclei, as was the cosmic microwave background (CMB), in a cyclic universe model. The key piece of observational evidence is that the amount of energy released in the conversion of hydrogen to helium in the universe is very close to the energy carried by the CMB, namely ~4.5 × 10-13 erg cm-3.

  14. 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.

  15. Multiple lensing of the cosmic microwave background anisotropies

    SciTech Connect

    Calabrese, M.; Fabbian, G.; Baccigalupi, C.; Carbone, C.; Baldi, M. E-mail: carmelita.carbone@brera.inaf.it E-mail: marco.baldi5@unibo.it

    2015-03-01

    We study the gravitational lensing effect on the Cosmic Microwave Background (CMB) anisotropies performing a ray-tracing of the primordial CMB photons through intervening large-scale structures (LSS) distribution predicted by N-Body numerical simulations with a particular focus on the precise recovery of the lens-induced polarized counterpart of the source plane. We apply both a multiple plane ray-tracing and an effective deflection approach based on the Born approximation to deflect the CMB photons trajectories through the simulated lightcone. We discuss the results obtained with both these methods together with the impact of LSS non-linear evolution on the CMB temperature and polarization power spectra. We compare our results with semi-analytical approximations implemented in Boltzmann codes like, e.g., CAMB. We show that, with our current N-body setup, the predicted lensing power is recovered with good accuracy in a wide range of multipoles while excess power with respect to semi-analytic prescriptions is observed in the lensing potential on scales ℓ ∼> 3000. We quantify the impact of the numerical effects connected to the resolution in the N-Body simulation together with the resolution and band-limit chosen to synthesise the CMB source plane. We found these quantities to be particularly important for the simulation of B-mode polarization power spectrum.

  16. 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.

  17. Searching for primordial magnetism with multifrequency cosmic microwave background experiments

    NASA Astrophysics Data System (ADS)

    Pogosian, Levon

    2014-03-01

    Bounds on the amplitude of a scale-invariant stochastic primordial magnetic field (PMF) can be significantly improved by measurements of the Faraday rotation (FR) of cosmic microwave background polarization. The mode-coupling correlations induced by FR make it possible to extract it from cross-correlations of the B-mode polarization with the E-mode and the temperature anisotropy. In this paper, we construct an estimator of the rotation measure that appropriately combines measurements of the FR from multiple frequency channels. We study the dependence of the signal-to-noise ratio in the PMF detection on the resolution and the noise of the detectors, as well as the removal of the weak lensing contribution and the Galactic FR. We show that a recently proposed space-based experiment Polarized Radiation Imaging and Spectroscopy Mission can detect magnetic fields of 0.1 nG strength at a 2σ level. Higher detection levels can be achieved by reducing the detector noise and improving the resolution or increasing the number of channels in the 30-70 GHz frequency range.

  18. 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.

  19. A framework for testing isotropy with the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Saadeh, Daniela; Feeney, Stephen M.; Pontzen, Andrew; Peiris, Hiranya V.; McEwen, Jason D.

    2016-10-01

    We present a new framework for testing the isotropy of the Universe using cosmic microwave background data, building on the nested-sampling ANICOSMO code. Uniquely, we are able to constrain the scalar, vector and tensor degrees of freedom alike; previous studies only considered the vector mode (linked to vorticity). We employ Bianchi type VIIh cosmologies to model the anisotropic Universe, from which other types may be obtained by taking suitable limits. In a separate development, we improve the statistical analysis by including the effect of Bianchi power in the high-ℓ, as well as the low-ℓ, likelihood. To understand the effect of all these changes, we apply our new techniques to Wilkinson Microwave Anisotropy Probe data. We find no evidence for anisotropy, constraining shear in the vector mode to (σV/H)0 < 1.7 × 10-10 (95 per cent confidence level). For the first time, we place limits on the tensor mode; unlike other modes, the tensor shear can grow from a near-isotropic early Universe. The limit on this type of shear is (σT, reg/H)0 < 2.4 × 10- 7 (95 per cent confidence level).

  20. Phase correlations in cosmic microwave background temperature maps

    NASA Astrophysics Data System (ADS)

    Coles, Peter; Dineen, Patrick; Earl, John; Wright, Dean

    2004-05-01

    We study the statistical properties of spherical harmonic modes of temperature maps of the cosmic microwave background. Unlike other studies, which focus mainly on properties of the amplitudes of these modes, we look instead at their phases. In particular, we present a simple measure of phase correlation that can be diagnostic of departures from the standard assumption that primordial density fluctuations constitute a statistically homogeneous and isotropic Gaussian random field, which should possess phases that are uniformly random on the unit circle. The method we discuss checks for the uniformity of the distribution of phase angles using a non-parametric descriptor based on the use of order statistics, which is known as Kuiper's statistic. The particular advantage of the method we present is that, when coupled to the judicious use of Monte Carlo simulations, it can deliver very interesting results from small data samples. In particular, it is useful for studying the properties of spherical harmonics at low l for which there are only a small number of independent values of m and which therefore furnish only a small number of phases for analysis. We apply the method to the COBE Differential Microwave Radiometer (DMR) and Wilkinson Microwave Anisotropy Probe (WMAP) sky maps, and find departures from uniformity in both. In the case of WMAP, our results probably reflect Galactic contamination or the known variation of signal-to-noise ratio across the sky rather than primordial non-Gaussianity.

  1. 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.

  2. 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.

  3. Well-proportioned universes suppress the cosmic microwave background quadrupole

    NASA Astrophysics Data System (ADS)

    Weeks, J.; Luminet, J.-P.; Riazuelo, A.; Lehoucq, R.

    2004-07-01

    A widespread myth asserts that all small universe models suppress the cosmic microwave background (CMB) quadrupole. In actual fact, some models suppress the quadrupole while others elevate it, according to whether their low-order modes are weak or strong relative to their high-order modes. Elementary geometrical reasoning shows that a model's largest dimension determines the rough value lmin at which the CMB power spectrum l(l + 1) Cl/2π effectively begins; for cosmologically relevant models, lmin <= 3. More surprisingly, elementary geometrical reasoning shows that further reduction of a model's smaller dimensions - with its largest dimension held fixed - serves to elevate modes in the neighbourhood of lmin relative to the high-l portion of the spectrum, rather than suppressing them as one might naively expect. Thus among the models whose largest dimension is comparable to or less than the horizon diameter, the low-order Cl tend to be relatively weak in well-proportioned spaces (spaces whose dimensions are approximately equal in all directions) but relatively strong in oddly proportioned spaces (spaces that are significantly longer in some directions and shorter in others). We illustrate this principle in detail for the special cases of rectangular 3-tori and spherical spaces. We conclude that well-proportioned spaces make the best candidates for a topological explanation of the low CMB quadrupole observed by COBE and WMAP.

  4. 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.

  5. 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.

  6. Cosmic microwave background constraints on secret interactions among sterile neutrinos

    NASA Astrophysics Data System (ADS)

    Forastieri, Francesco; Lattanzi, Massimiliano; Mangano, Gianpiero; Mirizzi, Alessandro; Natoli, Paolo; Saviano, Ninetta

    2017-07-01

    Secret contact interactions among eV sterile neutrinos, mediated by a massive gauge boson X (with MX ll MW), and characterized by a gauge coupling gX, have been proposed as a mean to reconcile cosmological observations and short-baseline laboratory anomalies. We constrain this scenario using the latest Planck data on Cosmic Microwave Background anisotropies, and measurements of baryon acoustic oscillations (BAO). We consistently include the effect of secret interactions on cosmological perturbations, namely the increased density and pressure fluctuations in the neutrino fluid, and still find a severe tension between the secret interaction framework and cosmology. In fact, taking into account neutrino scattering via secret interactions, we derive our own mass bound on sterile neutrinos and find (at 95 % CL) ms < 0.82 eV or ms < 0.29 eV from Planck alone or in combination with BAO, respectively. These limits confirm the discrepancy with the laboratory anomalies. Moreover, we constrain, in the limit of contact interaction, the effective strength GX to be < 2.8 (2.0) × 1010 GF from Planck (Planck+BAO). This result, together with the mass bound, strongly disfavours the region with MX ~ 0.1 MeV and relatively large coupling gX~ 10-1, previously indicated as a possible solution to the small scale dark matter problem.

  7. 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.

  8. Missing dust signature in the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Vavryčuk, Václav

    2017-09-01

    I examine a possible spectral distortion of the cosmic microwave background (CMB) due to its absorption by galactic and intergalactic dust. I show that even subtle intergalactic opacity of 1 × 10-7 mag h Gpc-1 at the CMB wavelengths in the local Universe causes non-negligible CMB absorption and decline of the CMB intensity because the opacity steeply increases with redshift. The CMB should be distorted even during the epoch of the Universe defined by redshifts z < 10. For this epoch, the maximum spectral distortion of the CMB is at least 20 × 10-22 W m-2 Hz-1 sr-1 at 300 GHz, which is well above the sensitivity of the COBE/FIRAS, WMAP or Planck flux measurements. If dust mass is considered to be redshift dependent with noticeable dust abundance at redshifts 2-4, the predicted CMB distortion would be even higher. The CMB would also be distorted in a perfectly transparent universe due to dust in galaxies, but this effect is lower by one order than that due to intergalactic opacity. The fact that the distortion of the CMB by dust is not observed is intriguing and questions either opacity and extinction law measurements or validity of the current model of the Universe.

  9. Cosmic sculpture: a new way to visualise the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Clements, D. L.; Sato, S.; Portela Fonseca, A.

    2017-01-01

    3D printing presents an attractive alternative to visual representation of physical datasets such as astronomical images that can be used for research, outreach or teaching purposes, and is especially relevant to people with a visual disability. We here report the use of 3D printing technology to produce a representation of the all-sky cosmic microwave background (CMB) intensity anisotropy maps produced by the Planck mission. The success of this work in representing key features of the CMB is discussed as is the potential of this approach for representing other astrophysical data sets. 3D printing such datasets represents a highly complementary approach to the usual 2D projections used in teaching and outreach work, and can also form the basis of undergraduate projects. The CAD files used to produce the models discussed in this paper are made available.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Imprint of DES superstructures on the cosmic microwave background

    DOE PAGES

    Kovács, A.; Sánchez, C.; García-Bellido, J.; ...

    2016-11-17

    Here, small temperature anisotropies in the Cosmic Microwave Background can be sourced by density perturbations via the late-time integrated Sachs-Wolfe effect. Large voids and superclusters are excellent environments to make a localized measurement of this tiny imprint. In some cases excess signals have been reported. We probed these claims with an independent data set, using the first year data of the Dark Energy Survey in a different footprint, and using a different super-structure finding strategy. We identified 52 large voids and 102 superclusters at redshiftsmore » $0.2 < z < 0.65$. We used the Jubilee simulation to a priori evaluate the optimal ISW measurement configuration for our compensated top-hat filtering technique, and then performed a stacking measurement of the CMB temperature field based on the DES data. For optimal configurations, we detected a cumulative cold imprint of voids with $$\\Delta T_{f} \\approx -5.0\\pm3.7~\\mu K$$ and a hot imprint of superclusters $$\\Delta T_{f} \\approx 5.1\\pm3.2~\\mu K$$ ; this is $$\\sim1.2\\sigma$$ higher than the expected $$|\\Delta T_{f}| \\approx 0.6~\\mu K$$ imprint of such super-structures in $$\\Lambda$$CDM. If we instead use an a posteriori selected filter size ($$R/R_{v}=0.6$$), we can find a temperature decrement as large as $$\\Delta T_{f} \\approx -9.8\\pm4.7~\\mu K$$ for voids, which is $$\\sim2\\sigma$$ above $$\\Lambda$$CDM expectations and is comparable to previous measurements made using SDSS super-structure data.« less

  16. Imprint of DES superstructures on the cosmic microwave background

    SciTech Connect

    Kovács, A.; Sánchez, C.; García-Bellido, J.; Nadathur, S.; Crittenden, R.; Gruen, D.; Huterer, D.; Bacon, D.; Clampitt, J.; DeRose, J.; Dodelson, S.; Gaztañaga, E.; Jain, B.; Kirk, D.; Lahav, O.; Miquel, R.; Naidoo, K.; Peacock, J. A.; Soergel, B.; Whiteway, L.; Abdalla, F. B.; Allam, S.; Annis, J.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Carrasco Kind, M.; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Eifler, T. F.; Finley, D. A.; Flaugher, B.; Fosalba, P.; Frieman, J.; Giannantonio, T.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Nord, B.; Ogando, R.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Sobreira, F.; Suchyta, E.; Swanson, M.; Tarle, G.; Thomas, D.; Walker, A. R.

    2016-11-17

    Here, small temperature anisotropies in the Cosmic Microwave Background can be sourced by density perturbations via the late-time integrated Sachs-Wolfe effect. Large voids and superclusters are excellent environments to make a localized measurement of this tiny imprint. In some cases excess signals have been reported. We probed these claims with an independent data set, using the first year data of the Dark Energy Survey in a different footprint, and using a different super-structure finding strategy. We identified 52 large voids and 102 superclusters at redshifts $0.2 < z < 0.65$. We used the Jubilee simulation to a priori evaluate the optimal ISW measurement configuration for our compensated top-hat filtering technique, and then performed a stacking measurement of the CMB temperature field based on the DES data. For optimal configurations, we detected a cumulative cold imprint of voids with $\\Delta T_{f} \\approx -5.0\\pm3.7~\\mu K$ and a hot imprint of superclusters $\\Delta T_{f} \\approx 5.1\\pm3.2~\\mu K$ ; this is $\\sim1.2\\sigma$ higher than the expected $|\\Delta T_{f}| \\approx 0.6~\\mu K$ imprint of such super-structures in $\\Lambda$CDM. If we instead use an a posteriori selected filter size ($R/R_{v}=0.6$), we can find a temperature decrement as large as $\\Delta T_{f} \\approx -9.8\\pm4.7~\\mu K$ for voids, which is $\\sim2\\sigma$ above $\\Lambda$CDM expectations and is comparable to previous measurements made using SDSS super-structure data.

  17. Cosmic microwave background anisotropies in the timescape cosmology

    NASA Astrophysics Data System (ADS)

    Nazer, M. Ahsan; Wiltshire, David L.

    2015-03-01

    We analyze the spectrum of cosmic microwave background (CMB) anisotropies in the timescape cosmology: a potentially viable alternative to homogeneous isotropic cosmologies without dark energy. We exploit the fact that the timescape cosmology is extremely close to the standard cosmology at early epochs to adapt existing numerical codes to produce CMB anisotropy spectra, and to match these as closely as possible to the timescape expansion history. A variety of matching methods are studied and compared. We perform Markov chain Monte Carlo analyses on the parameter space, and fit CMB multipoles 50 ≤ℓ≤2500 to the Planck satellite data. Parameter fits include a dressed Hubble constant, H0=61.0 km sec-1 Mpc-1 (±1.3 % stat) (±8 % sys), and a present void volume fraction fv 0=0.627 (±2.3 % stat) (±13 % sys). We find best fit likelihoods which are comparable to that of the best fit Λ CDM cosmology in the same multipole range. In contrast to earlier results, the parameter constraints afforded by this analysis no longer admit the possibility of a solution to the primordial lithium abundance anomaly. This issue is related to a strong constraint between the ratio of baryonic to nonbaryonic dark matter and the ratio of heights of the second and third acoustic peaks, which cannot be changed as long as the standard cosmology is assumed up to the surface of last scattering. These conclusions may change if backreaction terms are also included in the radiation-dominated primordial plasma.

  18. Imprint of DES superstructures on the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Kovács, A.; Sánchez, C.; García-Bellido, J.; Nadathur, S.; Crittenden, R.; Gruen, D.; Huterer, D.; Bacon, D.; Clampitt, J.; DeRose, J.; Dodelson, S.; Gaztañaga, E.; Jain, B.; Kirk, D.; Lahav, O.; Miquel, R.; Naidoo, K.; Peacock, J. A.; Soergel, B.; Whiteway, L.; Abdalla, F. B.; Allam, S.; Annis, J.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Carrasco Kind, M.; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Eifler, T. F.; Finley, D. A.; Flaugher, B.; Fosalba, P.; Frieman, J.; Giannantonio, T.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Nord, B.; Ogando, R.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Sobreira, F.; Suchyta, E.; Swanson, M.; Tarle, G.; Thomas, D.; Walker, A. R.; DES Collaboration

    2017-03-01

    Small temperature anisotropies in the cosmic microwave background (CMB) can be sourced by density perturbations via the late-time integrated Sachs-Wolfe (ISW) effect. Large voids and superclusters are excellent environments to make a localized measurement of this tiny imprint. In some cases excess signals have been reported. We probed these claims with an independent data set, using the first year data of the Dark Energy Survey (DES) in a different footprint, and using a different superstructure finding strategy. We identified 52 large voids and 102 superclusters at redshifts 0.2 < z < 0.65. We used the Jubilee simulation to a priori evaluate the optimal ISW measurement configuration for our compensated top-hat filtering technique, and then performed a stacking measurement of the CMB temperature field based on the DES data. For optimal configurations, we detected a cumulative cold imprint of voids with ΔTf ≈ -5.0 ± 3.7 μK and a hot imprint of superclusters ΔTf ≈ 5.1 ± 3.2 μK; this is ∼1.2σ higher than the expected |ΔTf| ≈ 0.6 μK imprint of such superstructures in Λ cold dark matter (ΛCDM). If we instead use an a posteriori selected filter size (R/Rv = 0.6), we can find a temperature decrement as large as ΔTf ≈ -9.8 ± 4.7 μK for voids, which is ∼2σ above ΛCDM expectations and is comparable to previous measurements made using Sloan Digital Sky Survey superstructure data.

  19. Imprint of DES superstructures on the cosmic microwave background

    SciTech Connect

    Kovács, A.; Sánchez, C.; García-Bellido, J.; Nadathur, S.; Crittenden, R.; Gruen, D.; Huterer, D.; Bacon, D.; Clampitt, J.; DeRose, J.; Dodelson, S.; Gaztañaga, E.; Jain, B.; Kirk, D.; Lahav, O.; Miquel, R.; Naidoo, K.; Peacock, J. A.; Soergel, B.; Whiteway, L.; Abdalla, F. B.; Allam, S.; Annis, J.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Carrasco Kind, M.; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Eifler, T. F.; Finley, D. A.; Flaugher, B.; Fosalba, P.; Frieman, J.; Giannantonio, T.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Nord, B.; Ogando, R.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Sobreira, F.; Suchyta, E.; Swanson, M.; Tarle, G.; Thomas, D.; Walker, A. R.

    2016-11-17

    Small temperature anisotropies in the Cosmic Microwave Background can be sourced by density perturbations via the late-time integrated Sachs-Wolfe effect. Large voids and superclusters are excellent environments to make a localized measurement of this tiny imprint. In some cases excess signals have been reported. We probed these claims with an independent data set, using the first year data of the Dark Energy Survey in a different footprint, and using a different super-structure finding strategy. We identified 52 large voids and 102 superclusters at redshifts $0.2 < z < 0.65$. We used the Jubilee simulation to a priori evaluate the optimal ISW measurement configuration for our compensated top-hat filtering technique, and then performed a stacking measurement of the CMB temperature field based on the DES data. For optimal configurations, we detected a cumulative cold imprint of voids with $\\Delta T_{f} \\approx -5.0\\pm3.7~\\mu K$ and a hot imprint of superclusters $\\Delta T_{f} \\approx 5.1\\pm3.2~\\mu K$ ; this is $\\sim1.2\\sigma$ higher than the expected $|\\Delta T_{f}| \\approx 0.6~\\mu K$ imprint of such super-structures in $\\Lambda$CDM. If we instead use an a posteriori selected filter size ($R/R_{v}=0.6$), we can find a temperature decrement as large as $\\Delta T_{f} \\approx -9.8\\pm4.7~\\mu K$ for voids, which is $\\sim2\\sigma$ above $\\Lambda$CDM expectations and is comparable to previous measurements made using SDSS super-structure data.

  20. 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.

  1. 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").

  2. 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.; hide

    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").

  3. 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.

  4. Cosmic Infrared Background ExpeRiment (CIBER): A probe of Extragalactic Background Light from reionization

    NASA Astrophysics Data System (ADS)

    Cooray, Asantha; Bock, Jamie; Kawada, Mitsunobu; Keating, Brian; Lange, Andrew; Lee, Dae-Hee; Levenson, Louis; Matsumoto, Toshio; Matsuura, Shuji; Renbarger, Tom; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko; Zemcov, Michael

    2012-08-01

    The Cosmic Infrared Background ExpeRiment (CIBER) is a rocket-borne absolute photometry imaging and spectroscopy experiment optimized to detect signatures of first-light galaxies present during reionization in the unresolved IR background. CIBER-I consists of a wide-field two-color camera for fluctuation measurements, a low-resolution absolute spectrometer for absolute EBL measurements, and a narrow-band imaging spectrometer to measure and correct scattered emission from the foreground zodiacal cloud. CIBER-I was successfully flown in February 2009 and July 2010 and four more flights are planned by 2014, including an upgrade (CIBER-II). We propose, after several additional flights of CIBER-I, an improved CIBER-II camera consisting of a wide-field 30 cm imager operating in 4 bands between 0.5 and 2.1 microns. It is designed for a high significance detection of unresolved IR background fluctuations at the minimum level necessary for reionization. With a FOV 50 to 2000 times larger than existing IR instruments on satellites, CIBER-II will carry out the definitive study to establish the surface density of sources responsible for reionization.

  5. Cosmic Infrared Background Experiment (CIBER): A Probe of Extragalactic Background Light from Reionization

    NASA Astrophysics Data System (ADS)

    Cooray, Asantha; Bock, Jamie; Kawada, Mitsunobu; Keating, Brian; Lee, Dae-Hee; Levenson, Louis; Matsumoto, Toshio; Matsuura, Shuji; Renbarger, Tom; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko; Zemcov, Michael

    2010-11-01

    The Cosmic Infrared Background ExpeRiment (CIBER) is a rocket-borne absolute photometry imaging and spectroscopy experiment optimized to detect signatures of first-light galaxies present during reionization in the unresolved IR background. CIBER-I consists of a wide-field two-color camera for fluctuation measurements, a low-resolution absolute spectrometer for EBL measurements, and a narrow-band imaging spectrometer to measure and correct scattered emission from the foreground zodiacal cloud. CIBER-I was successfully flown on February 25th, 2009 and is expected to be flown three more times over the next two years at six month intervals. CIBER-II is a wide-field 30 cm imager operating in 4 bands between 0.5 and 2.1 microns. It is designed for a high sigma detection of unresolved IR background fluctuations at the minimum level necessary for reionization. With an etendue (a figure-of-merit for survey studies) a factor of 50 to 500 larger than existing IR instruments on satellites, CIBER-II will carry out the definitive study to establish the surface density of sources responsible for reionization.

  6. Cosmic Infrared Background ExpeRiment (CIBER): A Probe of Extragalactic Background Light from Reionization

    NASA Astrophysics Data System (ADS)

    Cooray, A.; Bock, J.; Kawada, M.; Keating, B.; Lange, A.; Lee, D.-H.; Levenson, L.; Matsumoto, T.; Matsuura, S.; Renbarger, T.; Sullivan, I.; Tsumura, K.; Wada, T.; Zemcov, M.

    2009-12-01

    The Cosmic Infrared Background ExpeRiment (CIBER) is a rocket-borne absolute photometry imaging and spectroscopy experiment optimized to detect signatures of first-light galaxies present during reionization in the unresolved IR background. CIBER-I consists of a wide-field two-color camera for fluctuation measurements, a low-resolution absolute spectrometer for absolute EBL measurements, and a narrow-band imaging spectrometer to measure and correct scattered emission from the foreground zodiacal cloud. CIBER-I was successfully flown on February 25th, 2009 and has one more planned flight in early 2010. We propose, after several additional flights of CIBER-I an improved CIBER-II camera consisting of a wide-field 30 cm imager operating in 4 bands between 0.5 and 2.1 microns. It is designed for a high significance detection of unresolved IR background fluctuations at the minimum level necessary for reionization. With a FOV 50 to 2000 times larger than existing IR instruments on satellites, CIBER-II will carry out the definitive study to establish the surface density of sources responsible for reionization.

  7. 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

  8. COSMIC RAY BACKGROUND ANALYSIS FOR A CARGO CONTAINER COUNTER.

    SciTech Connect

    Ensslin, Norbert; Geist, W. H.; Lestone, J. P.; Mayo, D. R.; Menlove, Howard O.

    2001-01-01

    We have developed a new model for calculating the expected yield of cosmic-ray spallation neutrons in a Cargo Container Counter, and we have benchmarked the model against measurements made with several existing large neutron counters. We also developed two versions of a new measurement uncertainty prediction code based on Microsoft Excel spreadsheets. The codes calculate the minimum detectability limit for the Cargo Container Counter for either neutron singles or doubles counting, and also propagate the uncertainties associated with efficiency normalization flux monitors and cosmic ray flux monitors. This paper will describe the physics basis for this analysis, and the results obtained for several different counter designs.

  9. New probes of Cosmic Microwave Background large-scale anomalies

    NASA Astrophysics Data System (ADS)

    Aiola, Simone

    Fifty years of Cosmic Microwave Background (CMB) data played a crucial role in constraining the parameters of the LambdaCDM model, where Dark Energy, Dark Matter, and Inflation are the three most important pillars not yet understood. Inflation prescribes an isotropic universe on large scales, and it generates spatially-correlated density fluctuations over the whole Hubble volume. CMB temperature fluctuations on scales bigger than a degree in the sky, affected by modes on super-horizon scale at the time of recombination, are a clean snapshot of the universe after inflation. In addition, the accelerated expansion of the universe, driven by Dark Energy, leaves a hardly detectable imprint in the large-scale temperature sky at late times. Such fundamental predictions have been tested with current CMB data and found to be in tension with what we expect from our simple LambdaCDM model. Is this tension just a random fluke or a fundamental issue with the present model? In this thesis, we present a new framework to probe the lack of large-scale correlations in the temperature sky using CMB polarization data. Our analysis shows that if a suppression in the CMB polarization correlations is detected, it will provide compelling evidence for new physics on super-horizon scale. To further analyze the statistical properties of the CMB temperature sky, we constrain the degree of statistical anisotropy of the CMB in the context of the observed large-scale dipole power asymmetry. We find evidence for a scale-dependent dipolar modulation at 2.5sigma. To isolate late-time signals from the primordial ones, we test the anomalously high Integrated Sachs-Wolfe effect signal generated by superstructures in the universe. We find that the detected signal is in tension with the expectations from LambdaCDM at the 2.5sigma level, which is somewhat smaller than what has been previously argued. To conclude, we describe the current status of CMB observations on small scales, highlighting the

  10. Cosmic microwave background constraints for global strings and global monopoles

    NASA Astrophysics Data System (ADS)

    Lopez-Eiguren, Asier; Lizarraga, Joanes; Hindmarsh, Mark; Urrestilla, Jon

    2017-07-01

    We present the first cosmic microwave background (CMB) power spectra from numerical simulations of the global O(N) linear σ-model, with N=2,3, which have global strings and monopoles as topological defects. In order to compute the CMB power spectra we compute the unequal time correlators (UETCs) of the energy-momentum tensor, showing that they fall off at high wave number faster than naive estimates based on the geometry of the defects, indicating non-trivial (anti-)correlations between the defects and the surrounding Goldstone boson field. We obtain source functions for Einstein-Boltzmann solvers from the UETCs, using a recently developed method that improves the modelling at the radiation-matter transition. We show that the interpolation function that mimics the transition is similar to other defect models, but not identical, confirming the non-universality of the interpolation function. The CMB power spectra for global strings and global monopoles have the same overall shape as those obtained using the non-linear σ-model approximation, which is well captured by a large-N calculation. However, the amplitudes are larger than the large-N calculation would naively predict, and in the case of global strings much larger: a factor of 20 at the peak. Finally we compare the CMB power spectra with the latest CMB data in other to put limits on the allowed contribution to the temperature power spectrum at multipole l = 10 of 1.7% for global strings and 2.4% for global monopoles. These limits correspond to symmetry-breaking scales of 2.9× 1015 GeV (6.3× 1014 GeV with the expected logarithmic scaling of the effective string tension between the simulation time and decoupling) and 6.4× 1015 GeV respectively. The bound on global strings is a significant one for the ultra-light axion scenario with axion masses ma lesssim 10-28 eV . These upper limits indicate that gravitational waves from global topological defects will not be observable at the gravitational wave observatory

  11. 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.

  12. Cosmic microwave background: Polarization and temperature anisotropies from symmetric structures

    NASA Astrophysics Data System (ADS)

    Baccigalupi, Carlo

    1999-06-01

    Perturbations in the cosmic microwave background (CMB) are generated by primordial inhomogeneities. I consider the case of CMB anisotropies from one single ordered perturbation source, or seed, existing well before decoupling between matter and radiation. Such structures could have been left by high energy symmetries breaking in the early universe. I focus on the cases of spherical and cylindrical symmetry of the seed. I give general analytic expressions for the polarization and temperature linear perturbations, factoring out of the Fourier integral the dependence on the photon propagation direction and on the geometric coordinates describing the seed. I show how the CMB perturbations manifestly reflect the symmetries of their seeds. In particular, polarization is uniquely linked to the shape of the source because of its tensorial nature. CMB anisotropies are obtained with a line of sight integration. They are a function of the position and orientation of the seed along the photons path. This treatment highlights the undulatory properties of the CMB. I show with numerical examples how the polarization and temperature perturbations propagate beyond the size of their seeds, reaching the CMB sound horizon at the time considered. Just like the waves from a pebble thrown in a pond, CMB anisotropy from a seed intersecting the last scattering surface appears as a series of temperature and polarization waves surrounding the seed, extending on the scale of the CMB sound horizon at decoupling, roughly 1 deg in the sky. Each wave is characterized by its own value of the CMB perturbation, with the same mean amplitude of the signal coming from the seed interior; as expected for a linear structure with size L<=H-1 and density contrast δ at decoupling, the temperature anisotropy is δT/T~=δ(L/H-1)2, roughly ten times stronger than the polarization. These waves could allow one to distinguish relics from high energy processes of the early universe from pointlike astrophysical

  13. 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

  14. Detection of cosmic microwave background anisotropy at 1.8 deg: Theoretical implications on inflationary models

    NASA Astrophysics Data System (ADS)

    de Bernardis, Paolo; de Gasperis, Giancarlo; Masi, Silvia; Vittorio, Nicola

    1994-09-01

    Theoretical scenarios for the formation of large-scale structure in the universe are strongly constrained by ARGO (a balloon borne experiment reporting detection of cosmic microwave background (CMB) anisotropy at 1.8 deg) and Cosmic Background Explorer/Differential Microwave Radiometer (COBE/DMR). Here we consider flat hybrid models with either scale invariant or tilted (n not equal to 1) initial conditions. For n less than 1, we take into account the effect of a primordial background of gravitational waves, predicted by power-law inflation scenarios. The main result of our analysis is that the ARGO and COBE/DMR data select a range of values for the primordial spectral index: n = 0.95+0.25-0.15 (values of n outside this range can be rejected at more than 95% confidence level). These bounds are basically independent of the cosmological abundance of baryons (at least in the range allowed from primordial nucleosynthesis) and of the ratio of cold to hot dark matter. So, flat, cold, or mixed dark matter models, with scale-invariant initial conditions and a standard recombination history, successfully take into account the CMB anisotropy detected at intermediate and large angular scales.

  15. 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

  16. 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.

  17. Astroparticle Techniques: Simulating cosmic rays induced background radiation on aircrafts

    NASA Astrophysics Data System (ADS)

    Asorey, H.; Núñez, L. A.; Pérez Arias, C. Y.; Pinilla, S.; Quinonez, F.; Suárez-Durán, M.

    2017-07-01

    Incident cosmic ray fluxes over flying aircrafts are compared with those in Bucaramanga, Colombia and very significant differences are observed for proton and neutron fluxes. We also obtained that major contributions in the deposited energy by Cherenkov photons on blood plasma is in the UV-C band.

  18. Anisotropies in the gravitational wave background as a probe of the cosmic string network

    NASA Astrophysics Data System (ADS)

    Kuroyanagi, Sachiko; Takahashi, Keitaro; Yonemaru, Naoyuki; Kumamoto, Hiroki

    2017-02-01

    Pulsar timing arrays are powerful tools to test the existence of cosmic strings by searching for the gravitational wave (GW) background. The amplitude of the background connects to information on cosmic strings such as the tension and string network properties. In addition, one may be able to extract more information on the properties of cosmic strings by measuring anisotropies in the GW background. In this paper, we provide estimates of the level of anisotropy expected in the GW background generated by cusps on cosmic strings. We find that the anisotropy level strongly depends on the initial loop size α , and thus we may be able to put constraints on α by measuring the anisotropy of the GW background. We also find that certain regions of the parameter space can be probed by shifting the observation frequency of GWs.

  19. Microphysics of Cosmic Plasmas: Background, Motivation and Objectives

    NASA Astrophysics Data System (ADS)

    Balogh, André; Bykov, Andrei; Cargill, Peter; Dendy, Richard; Dudok de Wit, Thierry; Raymond, John

    With the maturing of space plasma research in the solar system, a more general approach to plasma physics in general, applied to cosmic plasmas, has become appropriate. There are both similarities and important differences in describing the phenomenology of space plasmas on scales from the Earth's magnetosphere to galactic and inter-galactic scales. However, there are important aspects in common, related to the microphysics of plasma processes. This introduction to a coordinated collection of papers that address the several aspects of the microphysics of cosmic plasmas that have unifying themes sets out the scope and ambition of the broad sweep of topics covered in the volume, together with an enumeration of the detailed objectives of the coverage.

  20. Microphysics of Cosmic Plasmas: Background, Motivation and Objectives

    NASA Astrophysics Data System (ADS)

    Balogh, André; Bykov, Andrei; Cargill, Peter; Dendy, Richard; Dudok de Wit, Thierry; Raymond, John

    2013-10-01

    With the maturing of space plasma research in the solar system, a more general approach to plasma physics in general, applied to cosmic plasmas, has become appropriate. There are both similarities and important differences in describing the phenomenology of space plasmas on scales from the Earth's magnetosphere to galactic and inter-galactic scales. However, there are important aspects in common, related to the microphysics of plasma processes. This introduction to a coordinated collection of papers that address the several aspects of the microphysics of cosmic plasmas that have unifying themes sets out the scope and ambition of the broad sweep of topics covered in the volume, together with an enumeration of the detailed objectives of the coverage.

  1. Testing New Physics with the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Gluscevic, Vera

    2013-01-01

    In my thesis work, I have developed and applied tests of new fundamental physics that utilize high-precision CMB polarization measurements. I especially focused on a wide class of dark energy models that propose existence of new scalar fields to explain accelerated expansion of the Universe. Such fields naturally exhibit a weak interaction with photons, giving rise to "cosmic birefringence"---a rotation of the polarization plane of light traveling cosmological distances, which alters the statistics of the CMB fluctuations in the sky by inducing a characteristic B-mode polarization. A birefringent rotation of the CMB would be smoking-gun evidence that dark energy is a dynamical component rather than a cosmological constant, while its absence gives clues about the allowed regions of the parameter space for new models. I developed a full-sky formalism to search for cosmic birefringence by cross-correlating CMB temperature and polarization maps, after allowing for the rotation angle to vary across the sky. With my collaborators, I also proposed a cross-correlation of the rotation-angle estimator with the CMB temperature as a novel statistical probe which can boost signal-to-noise in the case of marginal detection and help disentangle the underlying physical models. I then investigated the degeneracy between the rotation signal and the signals from other exotic scenarios that induce a similar B-mode polarization signature, such as chiral primordial gravitational waves, and demonstrated that these effects are completely separable. Finally, I applied this formalism to WMAP-7 data and derived the first CMB constraint on the power spectrum of the birefringent-rotation angle and presented forecasts for future experiments. To demonstrate the value of this analysis method beyond the search for direction-dependent cosmic birefringence, I have also used it to probe patchy screening from the epoch of cosmic reionization with WMAP-7 data.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Application of Monte Carlo algorithms to the Bayesian analysis of the Cosmic Microwave Background

    NASA Technical Reports Server (NTRS)

    Jewell, J.; Levin, S.; Anderson, C. H.

    2004-01-01

    Power spectrum estimation and evaluation of associated errors in the presence of incomplete sky coverage; nonhomogeneous, correlated instrumental noise; and foreground emission are problems of central importance for the extraction of cosmological information from the cosmic microwave background (CMB).

  9. Photon spectrum produced by the late decay of a cosmic neutrino background

    SciTech Connect

    Masso, E.; Toldra, R.

    1999-10-01

    We obtain the photon spectrum induced by a cosmic background of unstable neutrinos. We study the spectrum in a variety of cosmological scenarios and also we allow for the neutrinos having a momentum distribution (only a critical matter-dominated universe and neutrinos at rest have been considered until now). Our results can be helpful when extracting bounds on neutrino electric and magnetic moments from cosmic photon background observations. {copyright} {ital 1999} {ital The American Physical Society}

  10. 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.

  11. 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.

  12. DNDO Report: Predicting Solar Modulation Potentials for Modeling Cosmic Background Radiation

    SciTech Connect

    Behne, Patrick Alan

    2016-08-08

    The modeling of the detectability of special nuclear material (SNM) at ports and border crossings requires accurate knowledge of the background radiation at those locations. Background radiation originates from two main sources, cosmic and terrestrial. Cosmic background is produced by high-energy galactic cosmic rays (GCR) entering the atmosphere and inducing a cascade of particles that eventually impact the earth’s surface. The solar modulation potential represents one of the primary inputs to modeling cosmic background radiation. Usosokin et al. formally define solar modulation potential as “the mean energy loss [per unit charge] of a cosmic ray particle inside the heliosphere…” Modulation potential, a function of elevation, location, and time, shares an inverse relationship with cosmic background radiation. As a result, radiation detector thresholds require adjustment to account for differing background levels, caused partly by differing solar modulations. Failure to do so can result in higher rates of false positives and failed detection of SNM for low and high levels of solar modulation potential, respectively. This study focuses on solar modulation’s time dependence, and seeks the best method to predict modulation for future dates using Python. To address the task of predicting future solar modulation, we utilize both non-linear least squares sinusoidal curve fitting and cubic spline interpolation. This material will be published in transactions of the ANS winter meeting of November, 2016.

  13. Exploring Cosmic X-ray Source Polarization

    NASA Technical Reports Server (NTRS)

    Swank, Jean Hebb; Jahodal, K.; Kallman, T. R.; Kaaret, P.

    2008-01-01

    Cosmic X-ray sources are expected to be polarized, either because of their asymmetry and the role of scattering in their emission or the role of magnetic fields. Polarization at other wavelengths has been useful. X-ray polarization will provide a new handle on black hole parameters, in particular the spin, on accretion flows and outflows, on neutron star spin orientations and emission mechanisms, on the quantum mechanical effects of super-strong magnetic fields of magnetars, and on the structure of supernovae shocks. The proposed Gravity and Extreme Magnetism SMEX (GEMS) will use high efficiency polarimeters behind thin foil mirrors. The statistical sensitivity and control of systematics will allow measurement of polarization fractions as small as 1% from many galactic and extragalactic sources. Targets which should be polarized at the level that GEMS can easily measure include stellar black holes, Seyfert galaxies and quasars, blazars, rotation-powered and accretion-powered pulsars, magnetars, shell supernova remnants and pulsar wind nebulae. The polarimeters are Time Projection Chambers that allow reconstruction of images of photoelectron tracks for 2-10 keV Xrays. They can be deep without sacrificing modulation. These polarimeters do not image the sky, but the telescope point spread function and detector collimation allow structure to be resolved at the 10 arcmin level. Rotation of the spacecraft is not needed for the signal measurement in the Time Projection Chambers, but provides for measurement and correction of systematic errors. It also allows a small Bragg reflection soft X-ray experiment to be included that can be used for isolated neutron stars and blazars.

  14. The cosmic gamma-ray background from the annihilation of primordial stable neutral heavy leptons

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1978-01-01

    The spectra and intensities of gamma radiation from (1) a homogeneous cosmic lepton background (2) a possible lepton halo around the Galaxy, and (3) integrated background radiation from possible lepton halos around other galaxies and from rich galaxy clusters are examined. Heavy-lepton annihilation radiation from the halos of other galaxies accounts for at most 0.005 of the background intensity, and the radiation from rich clusters account for at most 0.00005 of the background intensity. It is suggested that lepton annihilation fluxes from a galactic halo would be confused with cosmic-ray produced radiation and would therefore be difficult to observe. Radiation from a homogeneous cosmological lepton background might account for approximately 0.0001 of the observed cosmic gamma ray background. Energy spectrum and isotropy are considered.

  15. 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

  16. LOWER BOUND ON THE COSMIC TeV GAMMA-RAY BACKGROUND RADIATION

    SciTech Connect

    Inoue, Yoshiyuki; Tanaka, Yasuyuki T.

    2016-02-20

    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{sup −8}(E/100 GeV){sup −0.55} exp(−E/2100GeV)[GeV cm{sup −2} s{sup −1} sr{sup −1}] < E{sup 2}dN/dE < 1.1 × 10{sup −7}(E/100 GeV){sup −0.49} [GeV cm{sup −2} s{sup −1} sr{sup −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.

  17. 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.

  18. SYSTEMATIC EFFECTS IN POLARIZING FOURIER TRANSFORM SPECTROMETERS FOR COSMIC MICROWAVE BACKGROUND OBSERVATIONS

    SciTech Connect

    Nagler, Peter C.; Tucker, Gregory S.; Fixsen, Dale J.; Kogut, Alan

    2015-11-15

    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.

  19. 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.

  20. Cosmic microwave background anomalies in an open universe.

    PubMed

    Liddle, Andrew R; Cortês, Marina

    2013-09-13

    We argue that the observed large-scale cosmic microwave anomalies, discovered by WMAP and confirmed by the Planck satellite, are most naturally explained in the context of a marginally open universe. Particular focus is placed on the dipole power asymmetry, via an open universe implementation of the large-scale gradient mechanism of Erickcek et al. Open inflation models, which are motivated by the string landscape and which can excite "supercurvature" perturbation modes, can explain the presence of a very-large-scale perturbation that leads to a dipole modulation of the power spectrum measured by a typical observer. We provide a specific implementation of the scenario which appears compatible with all existing constraints.

  1. Exploring cosmic strings: Observable effects and cosmological constraints

    NASA Astrophysics Data System (ADS)

    Sabancilar, Eray

    Observation of cosmic (super)strings can serve as a useful hint to understand the fundamental theories of physics, such as grand unified theories (GUTs) and/or superstring theory. In this regard, I present new mechanisms to produce particles from cosmic (super)strings, and discuss their cosmological and observational effects in this dissertation. The first chapter is devoted to a review of the standard cosmology, cosmic (super)strings and cosmic rays. The second chapter discusses the cosmological effects of moduli. Moduli are relatively light, weakly coupled scalar fields, predicted in supersymmetric particle theories including string theory. They can be emitted from cosmic (super)string loops in the early universe. Abundance of such moduli is constrained by diffuse gamma ray background, dark matter, and primordial element abundances. These constraints put an upper bound on the string tension as strong as Gmu ≲ 10-28 for a wide range of modulus mass m. If the modulus coupling constant is stronger than gravitational strength, modulus radiation can be the dominant energy loss mechanism for the loops. Furthermore, modulus lifetimes become shorter for stronger coupling. Hence, the constraints on string tension Gmu and modulus mass m are significantly relaxed for strongly coupled moduli predicted in superstring theory. Thermal production of these particles and their possible effects are also considered. In the third chapter, moduli emitted from cosmic string cusps are studied. Highly boosted modulus bursts emanating from cusps subsequently decay into gluons and generate hadronic cascades which in turn produce large number of neutrinos. For reasonable values of the modulus mass and coupling constant, observable ultra high energy neutrino fluxes can be produced for a wide range of string tension Gmu. The fourth chapter discusses cosmic rays produced by the charged particles ejected from cusps of superconducting cosmic strings. In many particle physics theories, cosmic

  2. Contribution of the first galaxies to the cosmic far-infrared/sub-millimeter background - I. Mean background level

    NASA Astrophysics Data System (ADS)

    De Rossi, María Emilia; Bromm, Volker

    2017-03-01

    We study the contribution of the first galaxies to the far-infrared/sub-millimeter (FIR/sub-mm) extragalactic background light (EBL) by implementing an analytical model for dust emission. We explore different dust models, assuming different grain-size distributions and chemical compositions. According to our findings, observed reradiated emission from dust in dwarf-size galaxies at z ∼ 10 would peak at a wavelength of ∼ 500 μm with observed fluxes of ∼10-3-10-2 nJy, which is below the capabilities of current observatories. In order to be detectable, model sources at these high redshifts should exhibit luminosities of ≳1012 L⊙, comparable to that of local ultraluminous systems. The FIR/sub-mm-EBL generated by primeval galaxies peaks at ∼ 500 μm, with an intensity ranging from ∼10-4 to 10-3 nW m-2 sr-1, depending on dust properties. These values are ∼3-4 orders of magnitude below the absolute measured cosmic background level, suggesting that the first galaxies would not contribute significantly to the observed FIR/sub-mm-EBL. Our model EBL exhibits a strong correlation with the dust-to-metal ratio, where we assume a fiducial value of D = 0.005, increasing almost proportionally to it. Thus, measurements of the FIR/sub-mm-EBL could provide constraints on the amount of dust in the early Universe. Even if the absolute signal from primeval dust emission may be undetectable, it might still be possible to obtain information about it by exploring angular fluctuations at ∼ 500 μm, close to the peak of dust emission from the first galaxies.

  3. On the cosmic-ray induced background in neutral pion production measurements with a BaF 2 multidetector

    NASA Astrophysics Data System (ADS)

    Badalà, A.; Barbera, R.; Palmeri, A.; Pappalardo, G. S.; Riggi, F.; Russo, A. C.; Russo, G.; Turrisi, R.

    1995-02-01

    The problem of the cosmic-ray induced background in neutral pion production measurements with barium fluoride multidetectors is discussed. As a reference example, the response to cosmic rays of the MEDEA photon spectrometer is studied. The interaction of the cosmic radiation with the experimental filter has been treated by means of full Monte Carlo computer simulations with the GEANT3 code. The results of the simulations are compared with experimental data and general criteria to minimize the cosmic background are discussed.

  4. 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.

  5. Cosmic Microwave Background Anisotropy Measurement from Python V

    NASA Astrophysics Data System (ADS)

    Coble, K.; Dodelson, S.; Dragovan, M.; Ganga, K.; Knox, L.; Kovac, J.; Ratra, B.; Souradeep, T.

    2003-02-01

    We analyze observations of the microwave sky made with the Python experiment in its fifth year of operation at the Amundsen-Scott South Pole Station in Antarctica. After modeling the noise and constructing a map, we extract the cosmic signal from the data. We simultaneously estimate the angular power spectrum in eight bands ranging from large (l~40) to small (l~260) angular scales, with power detected in the first six bands. There is a significant rise in the power spectrum from large to smaller (l~200) scales, consistent with that expected from acoustic oscillations in the early universe. We compare this Python V map to a map made from data taken in the third year of Python. Python III observations were made at a frequency of 90 GHz and covered a subset of the region of the sky covered by Python V observations, which were made at 40 GHz. Good agreement is obtained both visually (with a filtered version of the map) and via a likelihood ratio test.

  6. 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.

  7. Cosmic-ray composition measurements and cosmic ray background-free γ -ray observations with Cherenkov telescopes

    NASA Astrophysics Data System (ADS)

    Neronov, Andrii; Semikoz, Dmitri V.; Vovk, Ievgen; Mirzoyan, Razmik

    2016-12-01

    The muon component of extensive air showers (EAS) initiated by cosmic-ray particles carries information on the primary particle identity. We show that the muon content of EAS could be measured in a broad energy range from 10-100 TeV up to ultra-high-energy cosmic-ray range using wide field-of-view imaging atmospheric Cherenkov telescopes observing strongly inclined or nearly horizontal EAS from the ground of from high altitude. Cherenkov emission from muons in such EAS forms a distinct component (halo or tail) of the EAS image in the telescope camera. We show that detection of the muon signal could be used to measure composition of the cosmic-ray spectrum in the energy ranges of the knee, the ankle and of the Galactic-to-extragalactic transition. It could also be used to veto the cosmic-ray background in gamma-ray observations. This technique provides a possibility for up to 2 orders of magnitude improvement of sensitivity for γ -ray flux in the energy band above 10 PeV, compared to KASCADE-Grande, and an order-of-magnitude improvement of sensitivity in the multi-EeV energy band, compared to Pierre Auger Observatory.

  8. A Measurement of Secondary Cosmic Microwave Background Anisotropies with Two Years of South Pole Telescope Observations

    NASA Astrophysics Data System (ADS)

    Reichardt, C. L.; Shaw, L.; Zahn, O.; 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.; 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.

    2012-08-01

    We present the first three-frequency South Pole Telescope (SPT) cosmic microwave background (CMB) power spectra. The band powers presented here cover angular scales 2000 < l < 9400 in frequency bands centered at 95, 150, and 220 GHz. At these frequencies and angular scales, a combination of the primary CMB anisotropy, thermal and kinetic Sunyaev-Zel'dovich (SZ) effects, radio galaxies, and cosmic infrared background (CIB) contributes to the signal. We combine Planck/HFI and SPT data at 220 GHz to constrain the amplitude and shape of the CIB power spectrum and find strong evidence for nonlinear clustering. We explore the SZ results using a variety of cosmological models for the CMB and CIB anisotropies and find them to be robust with one exception: allowing for spatial correlations between the thermal SZ effect and CIB significantly degrades the SZ constraints. Neglecting this potential correlation, we find the thermal SZ power at 150 GHz and l = 3000 to be 3.65 ± 0.69 μK2, and set an upper limit on the kinetic SZ power to be less than 2.8 μK2 at 95% confidence. When a correlation between the thermal SZ and CIB is allowed, we constrain a linear combination of thermal and kinetic SZ power: D tSZ 3000 + 0.5D 3000 kSZ = 4.60 ± 0.63 μK2, consistent with earlier measurements. We use the measured thermal SZ power and an analytic, thermal SZ model calibrated with simulations to determine σ8 = 0.807 ± 0.016. Modeling uncertainties involving the astrophysics of the intracluster medium rather than the statistical uncertainty in the measured band powers are the dominant source of uncertainty on σ8. We also place an upper limit on the kinetic SZ power produced by patchy reionization; a companion paper uses these limits to constrain the reionization history of the universe.

  9. Gaussian statistics of the cosmic microwave background: Correlation of temperature extrema in the COBE DMR two-year sky maps

    NASA Technical Reports Server (NTRS)

    Kogut, A.; Banday, A. J.; Bennett, C. L.; Hinshaw, G.; Lubin, P. M.; Smoot, G. F.

    1995-01-01

    We use the two-point correlation function of the extrema points (peaks and valleys) in the Cosmic Background Explorer (COBE) Differential Microwave Radiometers (DMR) 2 year sky maps as a test for non-Gaussian temperature distribution in the cosmic microwave background anisotropy. A maximum-likelihood analysis compares the DMR data to n = 1 toy models whose random-phase spherical harmonic components a(sub lm) are drawn from either Gaussian, chi-square, or log-normal parent populations. The likelihood of the 53 GHz (A+B)/2 data is greatest for the exact Gaussian model. There is less than 10% chance that the non-Gaussian models tested describe the DMR data, limited primarily by type II errors in the statistical inference. The extrema correlation function is a stronger test for this class of non-Gaussian models than topological statistics such as the genus.

  10. Gaussian statistics of the cosmic microwave background: Correlation of temperature extrema in the COBE DMR two-year sky maps

    NASA Technical Reports Server (NTRS)

    Kogut, A.; Banday, A. J.; Bennett, C. L.; Hinshaw, G.; Lubin, P. M.; Smoot, G. F.

    1995-01-01

    We use the two-point correlation function of the extrema points (peaks and valleys) in the Cosmic Background Explorer (COBE) Differential Microwave Radiometers (DMR) 2 year sky maps as a test for non-Gaussian temperature distribution in the cosmic microwave background anisotropy. A maximum-likelihood analysis compares the DMR data to n = 1 toy models whose random-phase spherical harmonic components a(sub lm) are drawn from either Gaussian, chi-square, or log-normal parent populations. The likelihood of the 53 GHz (A+B)/2 data is greatest for the exact Gaussian model. There is less than 10% chance that the non-Gaussian models tested describe the DMR data, limited primarily by type II errors in the statistical inference. The extrema correlation function is a stronger test for this class of non-Gaussian models than topological statistics such as the genus.

  11. The cosmic neutrino background and the age of the Universe

    SciTech Connect

    De Bernardis, Francesco; Melchiorri, Alessandro; Verde, Licia; Jimenez, Raul E-mail: lverde@physics.upenn.edu

    2008-03-15

    We discuss the cosmological degeneracy of the age of the Universe, the Hubble parameter and the effective number of relativistic particles N{sub eff}. We show that independent determinations of the Hubble parameter H(z) such as those recently provided by Simon et al (2005 Phys. Rev. D 71 123001), combined with other cosmological data sets, can provide the most stringent constraints on N{sub eff}, yielding N{sub eff} = 3.7{sub -1.2}{sup +1.1} at 95% confidence level. A neutrino background is detected with high significance: N{sub eff}>1.8 at better than 99% confidence level. Constraints on the age of the Universe in the framework of an extra background of relativistic particles are improved by a factor of 3.

  12. Sparsity and cosmology: inverse problems in cosmic microwave background experiments

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    We propose a new method to better estimate and subtract the contribution of detected compact sources to the microwave sky. These bright compact source emissions contaminate the full-sky data over a significant fraction of the sky, and should therefore be accurately removed if a high resolution and full-sky estimate of the components is sought after. However the point source spectral variability hampers accurate blind source separation, even with state-of-the-art localized source separation techniques. In this work, we rather propose to estimate the flux of the brightest compact sources using a morphological separation approach, relying on a more sophisticated model for the background than in standard approaches. Essentially, this amounts to separate point sources with known support and shape from a background assumed sparse in the spherical harmonic domain. This approach is compared to standard local χ2 minimization modeling the background as a low order polynomial on WMAP realistic simulations. If in noisy situations estimating more than a few parameter does not improve flux recovery, in the first WMAP channels the proposed method leads to lower biases (typically by factors of 2) and increased robustness.

  13. 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.

  14. Measurement of the Intensity of the Cosmic Background Radiation at3.7 GHz

    SciTech Connect

    De Amici, G.; Smoot, G.F.; Aymon, J.; Bersanelli, M.; Kogut, A.; Levine, S.M.; Witebsky, C.

    1987-04-01

    We measured the temperature of the cosmic background radiation (CBR) at a frequency of 3.7 GHz (8.1 cm wavelength), using a total power, direct RF-gain receiver. The results give a brightness temperature, T{sub CBR}, of 2.58 {+-} 0.13 K (68% C.L.). Details of the instrument and of the experimental procedure are given. This measurement is part of a larger experiment to measure the spectrum of the Cosmic Background Radiation between 0.6 and 90 GHz (50 and 0.33 cm wavelength).

  15. Long-Wavelength Measurements of the Cosmic Microwave BackgroundRadiation Spectrum

    SciTech Connect

    Smoot, G.F.; Bensadoun, M.; Bersanelli, M.; pDe Amici, G.; Kogut,A.; Levine, S.; Witebsky, C.

    1987-02-01

    We have measured the temperature of the cosmic microwave background radiation at wavelengths of 0.33, 3.0, 8.2 and 21.3 cm. These measurements represent a continuation of the work reported by Smoot et al. (1985). The new results have a weighted average of 2.70 {+-} 0.05 K and are consistent with past measurements. They limit the possible distortion of the cosmic microwave background radiation spectrum to less than 6%. The results of all measurements to date are consistent with a Planckian spectrum with temperature 2.74 {+-} 0.02 K spanning a wavelength range of 0.1 to 21 cm.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Cosmic microwave background anisotropies in cold dark matter models with cosmological constant: The intermediate versus large angular scales

    NASA Technical Reports Server (NTRS)

    Stompor, Radoslaw; Gorski, Krzysztof M.

    1994-01-01

    We obtain predictions for cosmic microwave background anisotropies at angular scales near 1 deg in the context of cold dark matter models with a nonzero cosmological constant, normalized to the Cosmic Background Explorer (COBE) Differential Microwave Radiometer (DMR) detection. The results are compared to those computed in the matter-dominated models. We show that the coherence length of the Cosmic Microwave Background (CMB) anisotropy is almost insensitive to cosmological parameters, and the rms amplitude of the anisotropy increases moderately with decreasing total matter density, while being most sensitive to the baryon abundance. We apply these results in the statistical analysis of the published data from the UCSB South Pole (SP) experiment (Gaier et al. 1992; Schuster et al. 1993). We reject most of the Cold Dark Matter (CDM)-Lambda models at the 95% confidence level when both SP scans are simulated together (although the combined data set renders less stringent limits than the Gaier et al. data alone). However, the Schuster et al. data considered alone as well as the results of some other recent experiments (MAX, MSAM, Saskatoon), suggest that typical temperature fluctuations on degree scales may be larger than is indicated by the Gaier et al. scan. If so, CDM-Lambda models may indeed provide, from a point of view of CMB anisotropies, an acceptable alternative to flat CDM models.

  1. Cosmic microwave background anisotropies in cold dark matter models with cosmological constant: The intermediate versus large angular scales

    NASA Technical Reports Server (NTRS)

    Stompor, Radoslaw; Gorski, Krzysztof M.

    1994-01-01

    We obtain predictions for cosmic microwave background anisotropies at angular scales near 1 deg in the context of cold dark matter models with a nonzero cosmological constant, normalized to the Cosmic Background Explorer (COBE) Differential Microwave Radiometer (DMR) detection. The results are compared to those computed in the matter-dominated models. We show that the coherence length of the Cosmic Microwave Background (CMB) anisotropy is almost insensitive to cosmological parameters, and the rms amplitude of the anisotropy increases moderately with decreasing total matter density, while being most sensitive to the baryon abundance. We apply these results in the statistical analysis of the published data from the UCSB South Pole (SP) experiment (Gaier et al. 1992; Schuster et al. 1993). We reject most of the Cold Dark Matter (CDM)-Lambda models at the 95% confidence level when both SP scans are simulated together (although the combined data set renders less stringent limits than the Gaier et al. data alone). However, the Schuster et al. data considered alone as well as the results of some other recent experiments (MAX, MSAM, Saskatoon), suggest that typical temperature fluctuations on degree scales may be larger than is indicated by the Gaier et al. scan. If so, CDM-Lambda models may indeed provide, from a point of view of CMB anisotropies, an acceptable alternative to flat CDM models.

  2. CUBIC - A non-dispersive Diffuse X-ray Background spectrometer. [Cosmic Unresolved X-ray Background Instrument

    NASA Technical Reports Server (NTRS)

    Burrows, David N.; Skinner, Mark A.; Antunes, Alexander J. D.; Catalano, Mark A.; Cocklin, Eric J.; Engel, Leland G.; Entingh, Timothy J.; Garmire, Gordon P.; Green, Roland; Kelly, Douglas A.

    1992-01-01

    The Cosmic Unresolved X-ray Background Instrument using CCDs (CUBIC) is designed to obtain spectral observations of the Diffuse X-ray Background (DXRB) with moderate spectral resolution over the energy range 0.2-10 keV, using mechanically-collimated CCDs. At this time, it is the only planned satellite payload devoted to the study of the spectrum of the DXRB. Over the anticipated 3 year lifetime of the satellite, CUBIC will be able to study up to 50 percent of the sky with 5 x 5 deg spatial resolution for the subkilovolt Galactic diffuse background, and with 10 x 10 deg spatial resolution for the extragalactic diffuse background above 2 keV. CUBIC will obtain high quality nondispersive spectra of soft X-ray emission from the interstellar medium, supernova remnants, and some bright sources, and will make a sensitive seach for line emission or other features in the extragalactic cosmic X-ray background from 2-10 keV.

  3. CUBIC - A non-dispersive Diffuse X-ray Background spectrometer. [Cosmic Unresolved X-ray Background Instrument

    NASA Technical Reports Server (NTRS)

    Burrows, David N.; Skinner, Mark A.; Antunes, Alexander J. D.; Catalano, Mark A.; Cocklin, Eric J.; Engel, Leland G.; Entingh, Timothy J.; Garmire, Gordon P.; Green, Roland; Kelly, Douglas A.

    1992-01-01

    The Cosmic Unresolved X-ray Background Instrument using CCDs (CUBIC) is designed to obtain spectral observations of the Diffuse X-ray Background (DXRB) with moderate spectral resolution over the energy range 0.2-10 keV, using mechanically-collimated CCDs. At this time, it is the only planned satellite payload devoted to the study of the spectrum of the DXRB. Over the anticipated 3 year lifetime of the satellite, CUBIC will be able to study up to 50 percent of the sky with 5 x 5 deg spatial resolution for the subkilovolt Galactic diffuse background, and with 10 x 10 deg spatial resolution for the extragalactic diffuse background above 2 keV. CUBIC will obtain high quality nondispersive spectra of soft X-ray emission from the interstellar medium, supernova remnants, and some bright sources, and will make a sensitive seach for line emission or other features in the extragalactic cosmic X-ray background from 2-10 keV.

  4. CMBEASY: An object-oriented code for the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Doran, Michael; Seljak, Uros; Zaldarriaga, Matias

    2010-07-01

    CMBEASY is a software package for calculating the evolution of density fluctuations in the universe. Most notably, the Cosmic Microwave Background temperature anisotropies. It features a Markov Chain Monte Carlo driver and many routines to compute likelihoods of any given model. It is based on the CMBFAST package by Uros Seljak and Matias Zaldarriaga.

  5. Monte Carlo Algorithms for a Bayesian Analysis of the Cosmic Microwave Background

    NASA Technical Reports Server (NTRS)

    Jewell, Jeffrey B.; Eriksen, H. K.; ODwyer, I. J.; Wandelt, B. D.; Gorski, K.; Knox, L.; Chu, M.

    2006-01-01

    A viewgraph presentation on the review of Bayesian approach to Cosmic Microwave Background (CMB) analysis, numerical implementation with Gibbs sampling, a summary of application to WMAP I and work in progress with generalizations to polarization, foregrounds, asymmetric beams, and 1/f noise is given.

  6. Balloon-based measurements of the cosmic background radiation. [with Far IR spectrometer

    NASA Technical Reports Server (NTRS)

    Mather, J. C.; Richards, P. L.; Woody, D. P.

    1974-01-01

    A balloon-borne liquid-helium-cooled spectrometer was developed and flown to measure the cosmic background radiation in the 3- to 18-per-cm region. It features a cooled horn antenna, a polarizing Michelson interferometer, and a germanium bolometer. These design features and the performance of the instrument are discussed.

  7. Monte Carlo Algorithms for a Bayesian Analysis of the Cosmic Microwave Background

    NASA Technical Reports Server (NTRS)

    Jewell, Jeffrey B.; Eriksen, H. K.; ODwyer, I. J.; Wandelt, B. D.; Gorski, K.; Knox, L.; Chu, M.

    2006-01-01

    A viewgraph presentation on the review of Bayesian approach to Cosmic Microwave Background (CMB) analysis, numerical implementation with Gibbs sampling, a summary of application to WMAP I and work in progress with generalizations to polarization, foregrounds, asymmetric beams, and 1/f noise is given.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

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

    PubMed

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

    2013-03-08

    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.

  14. Correlations between 21-cm radiation and the cosmic microwave background from active sources

    NASA Astrophysics Data System (ADS)

    Berndsen, Aaron; Pogosian, Levon; Wyman, Mark

    2010-09-01

    Neutral hydrogen is ubiquitous, absorbing and emitting 21-cm radiation throughout much of the Universe's history. Active sources of perturbations, such as cosmic strings, would generate simultaneous perturbations in the distribution of neutral hydrogen and in the cosmic microwave background (CMB) radiation from recombination. Moving strings would create wakes leading to 21-cm brightness fluctuations, while also perturbing CMB light via the Gott-Kaiser-Stebbins effect. This would lead to spatial correlations between the 21-cm and CMB anisotropies. Passive sources, like inflationary perturbations, predict no cross-correlations prior to the onset of reionization. Thus, observation of any cross-correlation between CMB and 21-cm radiation from dark ages would constitute evidence for new physics. We calculate the cosmic string-induced correlations between CMB and 21-cm radiation and evaluate their observability.

  15. Wavelet analysis and the detection of non-Gaussianity in the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Hobson, M. P.; Jones, A. W.; Lasenby, A. N.

    1999-10-01

    We investigate the use of wavelet transforms in detecting and characterizing non-Gaussian structure in maps of the cosmic microwave background (CMB). We apply the method to simulated maps of the Kaiser-Stebbins effect resulting from cosmic strings, on to which Gaussian signals of varying amplitudes are superposed. We find that the method significantly outperforms standard techniques based on measuring the moments of the pixel temperature distribution. We also compare the results with those obtained using techniques based on Minkowski functionals, and we again find the wavelet method to be superior. In particular, using the wavelet technique, we find that it is possible to detect non-Gaussianity even in the presence of a superposed Gaussian signal with 3 times the rms amplitude of the original cosmic string map. We also find that the wavelet technique is useful in characterizing the angular scales at which the non-Gaussian signal occurs.

  16. Detection of trans-Planckian effects in the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Groeneboom, Nicolaas E.; Elgarøy, Øystein

    2008-02-01

    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.

  17. 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.

  18. Circular dichroism, magnetic knots, and the spectropolarimetry of the cosmic microwave background

    SciTech Connect

    Giovannini, Massimo

    2010-01-15

    When the last electron-photon scattering takes place in a magnetized environment, the degree of circular polarization of the outgoing radiation depends upon the magnetic field strength. After deriving the scattering matrix of the process, the generalized radiative transfer equations are deduced in the presence of the relativistic fluctuations of the geometry and for all the four brightness perturbations. The new system of equations is solved under the assumption that the incident radiation is not polarized. The induced V-mode polarization is analyzed both analytically and numerically. The corresponding angular power spectra are calculated and compared with the measured (or purported) values of the linear polarizations (i.e. E mode and B mode) as they arise in the concordance model and in its neighboring extensions. Possible connections between the V-mode polarization of the cosmic microwave background and the topological properties of the magnetic flux lines prior to equality are outlined and briefly explored in analogy with the physics of magnetized sunspots.

  19. 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.

  20. 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.

  1. A MEASUREMENT OF SECONDARY COSMIC MICROWAVE BACKGROUND ANISOTROPIES WITH TWO YEARS OF SOUTH POLE TELESCOPE OBSERVATIONS

    SciTech Connect

    Reichardt, C. L.; George, E. M.; Holzapfel, W. L.; Shaw, L.; Zahn, O.; Aird, K. A.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Hoover, S.; Cho, H. M.; De Haan, T.; Dobbs, M. A.; Dudley, J.; Holder, G. P.; Halverson, N. W.; Hou, Z.; and others

    2012-08-10

    We present the first three-frequency South Pole Telescope (SPT) cosmic microwave background (CMB) power spectra. The band powers presented here cover angular scales 2000 < l < 9400 in frequency bands centered at 95, 150, and 220 GHz. At these frequencies and angular scales, a combination of the primary CMB anisotropy, thermal and kinetic Sunyaev-Zel'dovich (SZ) effects, radio galaxies, and cosmic infrared background (CIB) contributes to the signal. We combine Planck/HFI and SPT data at 220 GHz to constrain the amplitude and shape of the CIB power spectrum and find strong evidence for nonlinear clustering. We explore the SZ results using a variety of cosmological models for the CMB and CIB anisotropies and find them to be robust with one exception: allowing for spatial correlations between the thermal SZ effect and CIB significantly degrades the SZ constraints. Neglecting this potential correlation, we find the thermal SZ power at 150 GHz and l = 3000 to be 3.65 {+-} 0.69 {mu}K{sup 2}, and set an upper limit on the kinetic SZ power to be less than 2.8 {mu}K{sup 2} at 95% confidence. When a correlation between the thermal SZ and CIB is allowed, we constrain a linear combination of thermal and kinetic SZ power: D{sup tSZ}{sub 3000} + 0.5D{sub 3000}{sup kSZ} = 4.60 {+-} 0.63 {mu}K{sup 2}, consistent with earlier measurements. We use the measured thermal SZ power and an analytic, thermal SZ model calibrated with simulations to determine {sigma}{sub 8} = 0.807 {+-} 0.016. Modeling uncertainties involving the astrophysics of the intracluster medium rather than the statistical uncertainty in the measured band powers are the dominant source of uncertainty on {sigma}{sub 8}. We also place an upper limit on the kinetic SZ power produced by patchy reionization; a companion paper uses these limits to constrain the reionization history of the universe.

  2. 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.

  3. 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.

  4. 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.; hide

    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.

  5. Exploring the moon. [personal historical background perspective

    NASA Technical Reports Server (NTRS)

    Jastrow, R.

    1981-01-01

    The genesis of lunar exploration programs is described. The idea that the dead moon could give important clues about the origin of the solar system germinated into plans for a soft landing on the moon and then into the Apollo program. The exchanges between NASA scientists and other astronomers that led to these plans are recounted.

  6. 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).

  7. Neutrino Physics from the Cosmic Microwave Background and Large-Scale Structure

    NASA Astrophysics Data System (ADS)

    Abazajian, Kevork N.; Kaplinghat, Manoj

    2016-10-01

    Cosmology and neutrino physics have converged into a recent discovery era. The success of the standard model of cosmology in explaining the cosmic microwave background and cosmological large-scale structure data allows for the possibility of measuring the absolute neutrino mass and providing exquisite constraints on the number of light degrees of freedom, including neutrinos. This sensitivity to neutrino physics requires the validity of some of the assumptions, including general relativity, inflationary cosmology, and standard thermal history, many of which can be tested with cosmological data. This sensitivity is also predicated on the robust handling of systematic uncertainties associated with different cosmological observables. We review several past, current, and future measurements of the cosmic microwave background and cosmological large-scale structure that allow us to do fundamental neutrino physics with cosmology.

  8. Electromagnetic Design of Feedhorn-Coupled Transition-Edge Sensors for Cosmic Microwave Background Polarimetry

    NASA Astrophysics Data System (ADS)

    Chuss, D. T.; Bennett, C. L.; Costen, N.; Crowe, E.; Denis, K.; Eimer, J. R.; Lourie, N.; Marriage, T. A.; Moseley, S. H.; Rostem, K.; Stevenson, T. R.; Towner, D.; U-Yen, K.; Voellmer, G.; Wollack, E. J.; Zeng, L.

    2012-06-01

    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 feedhorn 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).

  9. General constraints on dark matter decay from the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Slatyer, Tracy R.; Wu, Chih-Liang

    2017-01-01

    Precise measurements of the temperature and polarization anisotropies of the cosmic microwave background can be used to constrain the annihilation and decay of dark matter. In this work, we demonstrate via principal component analysis that the imprint of dark matter decay on the cosmic microwave background can be approximately parametrized by a single number for any given dark matter model. We develop a simple prescription for computing this model-dependent detectability factor, and demonstrate how this approach can be used to set model-independent bounds on a large class of decaying dark matter scenarios. We repeat our analysis for decay lifetimes shorter than the age of the Universe, allowing us to set constraints on metastable species other than the dark matter decaying at early times, and decays that only liberate a tiny fraction of the dark matter mass energy. We set precise bounds and validate our principal component analysis using a Markov chain Monte Carlo approach and Planck 2015 data.

  10. Cosmic infrared background anisotropies as a window into primordial non-Gaussianity

    NASA Astrophysics Data System (ADS)

    Tucci, Marco; Desjacques, Vincent; Kunz, Martin

    2016-12-01

    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.

  11. 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

  12. Cosmic background anisotropy induced by isotropic, flat-spectrum gravitational-wave perturbations

    SciTech Connect

    Starobinskii, A.A.

    1985-05-01

    A calculation is made of the temperature anisotropy that would be produced in the cosmic microwave background by an isotropic, stochastic ensemble of primordial gravitational waves having a flat initial spectrum. On angular scales THETA > 2 the anisotropy autocorrelation function has practically the same multipole dependence as previously established for the case of flat-spectrum adiabatic perturbations, while on scales THETA < 1 the anisotropy becomes insignificant. Upper limits are placed on the gravitational-wave amplitude and on the expected quadrupole anisotropy.

  13. 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.

  14. Low Frequency measurment of the Spectrum of the Cosmic BackgroundRadiation

    SciTech Connect

    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.

  15. New measurements of the cosmic background radiation temperature at 3. 3 millimeter wavelength

    SciTech Connect

    Witebsky, C.; Smoot, G.; De amici, G.; Friedman, S.D.

    1986-11-01

    The results of measurements of the cosmic background radiation (CBR) at 3.3 mm are reported, and the instrument, system operation, and data analysis procedures are described in detail. A CBR brightness temperature of 2.57 K with a 1 sigma uncertainty of + or - 0.12 K is obtained. The results are compared with measurements by other authors, and the cold-load antenna temperature and atmospheric model used in the study are discussed in appendices. 32 references.

  16. Theoretical bounds on the tensor-to-scalar ratio in the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Boubekeur, Lotfi

    2013-03-01

    Tensor modes in the cosmic microwave background are one of the most robust signatures of inflation. We derive theoretical bounds on the tensor fraction, as a generalization of the well-known Lyth bound. Under reasonable assumptions, the new bounds are at least 2 orders of magnitude stronger than the original one. We comment on a previously derived generalization, the so-called Efstathiou-Mack relationship. We also derive a new absolute upper bound on tensors using de Sitter entropy bounds.

  17. Cosmic background anisotropy studies at 10 degree angular scales with a HEMT radiometer

    SciTech Connect

    Gaier, T.; Schuster, J.; Lubin, P. )

    1990-01-15

    An expedition to the Amundsen-Scott South Pole Station was recently mounted to measure medium to large angular scale fluctuations in the cosmic background radiation (CBR) at 15 and 25 GHz. Preliminary results are reported in this paper. No fluctuations have been detected as yet and data analysis is proceeding using likelihood ratio tests to set upper limits of {Delta}{ital T}/{ital T} for models which may be constrained by this experiment.

  18. Fractality of Isotherms of the Cosmic Microwave Background Based on Data from the Planck Spacecraft

    NASA Astrophysics Data System (ADS)

    Mylläri, A. A.; Raikov, A. A.; Orlov, V. V.; Tarakanov, P. A.; Yershov, V. N.; Yezhkov, M. Y.

    2016-03-01

    A system of isophotes of the cosmic microwave background (CMB) is constructed for several regions on the celestial sphere using data from the Planck spacecraft. The fractal dimensionality of the isotherms is estimated to be Dc ≈ 1.78 ± 0.03. Our results agree with earlier work based on the ILC charts with WMAP data. Our simulations confirm the previous conclusion that a similar dimensionality is obtained for a gaussian spectrum of initial perturbations.

  19. COMPASS: An Upper Limit on Cosmic Microwave Background Polarization at an Angular Scale of 20'

    NASA Astrophysics Data System (ADS)

    Farese, Philip C.; Dall'Oglio, Giorgio; Gundersen, Joshua O.; Keating, Brian G.; Klawikowski, Slade; Knox, Lloyd; Levy, Alan; Lubin, Philip M.; O'Dell, Chris W.; Peel, Alan; Piccirillo, Lucio; Ruhl, John; Timbie, Peter T.

    2004-08-01

    COMPASS is an on-axis 2.6 m telescope coupled to a correlation polarimeter operating at a wavelength of 1 cm. The entire instrument was built specifically for cosmic microwave background (CMB) polarization studies. We report here on observations of 2001 February-April using this system. We set an upper limit on E-mode polarized anisotropies of 1036 μK2 (95% confidence limit) in the l range 93-555.

  20. Search for cosmic-microwave-background anisotropies at degree angular scales: the ARGO 1993 experiment.

    NASA Astrophysics Data System (ADS)

    de Bernardis, P.; Aquilini, E.; Boscaleri, A.; de Petris, M.; Gervasi, M.; Martinis, L.; Masi, S.; Natale, V.; Palumbo, P.; Scaramuzzi, F.

    1993-12-01

    The authors describe a balloon-borne telescope, optimized for observations of the cosmic microwave background (CMB) anisotropies in the mm wavelength region, at angular scales around 1°. They stress the scientific motivations for these measurements and the problematics driving the experiment design. Using large throughput bolometers cooled at 0.3K one has a sensitivity high enough to detect CMB anisotropies at level ΔT/T ≡ 10-5 in few seconds of integration time.

  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. 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.

  3. 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.

  4. Cosmic Explorers and Star Docent Youth Programs at Henize Observatory

    NASA Astrophysics Data System (ADS)

    Kabbes, J.

    2013-04-01

    The Karl G. Henize Observatory at Harper Community College has long served Harper students and the community. College students fulfill observing requirements for astronomy and physical science classes while the general public views objects through a variety of telescopes. In the spring of 2011, the observatory was in trouble. The long time observatory manager had left, the volunteer staff consisted of two individuals, and the Astronomy Club, which traditionally provided staff to operate the observatory, was moribund. We only drew 20-30 visitors for our bi-weekly public sessions. To face such a challenge, two recent complimentary programs, The Cosmic Explorers for grades 3-6 and the Star Docents for students in grades 7-12 were implemented.

  5. 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.

  6. Hierarchical Bayesian detection algorithm for early-universe relics in the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Feeney, Stephen M.; Johnson, Matthew C.; McEwen, Jason D.; Mortlock, Daniel J.; Peiris, Hiranya V.

    2013-08-01

    A number of theoretically well-motivated additions to the standard cosmological model predict weak signatures in the form of spatially localized sources embedded in the cosmic microwave background (CMB) fluctuations. We present a hierarchical Bayesian statistical formalism and a complete data analysis pipeline for testing such scenarios. We derive an accurate approximation to the full posterior probability distribution over the parameters defining any theory that predicts sources embedded in the CMB, and perform an extensive set of tests in order to establish its validity. The approximation is implemented using a modular algorithm, designed to avoid a posteriori selection effects, which combines a candidate-detection stage with a full Bayesian model-selection and parameter-estimation analysis. We apply this pipeline to theories that predict cosmic textures and bubble collisions, extending previous analyses by using: (1) adaptive-resolution techniques, allowing us to probe features of arbitrary size, and (2) optimal filters, which provide the best possible sensitivity for detecting candidate signatures. We conclude that the WMAP 7-year data do not favor the addition of either cosmic textures or bubble collisions to ΛCDM, and place robust constraints on the predicted number of such sources. The expected numbers of bubble collisions and cosmic textures on the CMB sky within our detection thresholds are constrained to be fewer than 4.0 and 5.2 at 95% confidence, respectively.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  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. Advanced Undergraduate Computer Based Astronomy Lab. The 3K Cosmic Microwave Background Radiation (CMBR).

    NASA Astrophysics Data System (ADS)

    Slovak, M. H.

    2002-05-01

    A challenging computer based astronomy lab for advanced astronomy undergraduate students has been developed using satellite (COBE) and ground-based observations of the 3K cosmic microwave background radiation (CMBR). Students are provided the observations and background information on the discovery and interpretation of the CMBR. They also review relevant radiation laws such as the Stefan-Boltzmann law and Wein's law. The data are modeled using Microsoft(c) Excel to calculate a Planckian intensity distribution in order to determine the temperature and peak wavelength of the CMBR. This lab is one in a series being designed to provide astronomy majors experience in mathematically modeling astronomical data.

  13. SPACE: the spectroscopic all-sky cosmic explorer

    NASA Astrophysics Data System (ADS)

    Cimatti, A.; Robberto, M.; Baugh, C.; Beckwith, S. V. W.; Content, R.; Daddi, E.; De Lucia, G.; Garilli, B.; Guzzo, L.; Kauffmann, G.; Lehnert, M.; Maccagni, D.; Martínez-Sansigre, A.; Pasian, F.; Reid, I. N.; Rosati, P.; Salvaterra, R.; Stiavelli, M.; Wang, Y.; Zapatero Osorio, M.; Balcells, M.; Bersanelli, M.; Bertoldi, F.; Blaizot, J.; Bottini, D.; Bower, R.; Bulgarelli, A.; Burgasser, A.; Burigana, C.; Butler, R. C.; Casertano, S.; Ciardi, B.; Cirasuolo, M.; Clampin, M.; Cole, S.; Comastri, A.; Cristiani, S.; Cuby, J.-G.; Cuttaia, F.; de Rosa, A.; Sanchez, A. Diaz; di Capua, M.; Dunlop, J.; Fan, X.; Ferrara, A.; Finelli, F.; Franceschini, A.; Franx, M.; Franzetti, P.; Frenk, C.; Gardner, Jonathan P.; Gianotti, F.; Grange, R.; Gruppioni, C.; Gruppuso, A.; Hammer, F.; Hillenbrand, L.; Jacobsen, A.; Jarvis, M.; Kennicutt, R.; Kimble, R.; Kriek, M.; Kurk, J.; Kneib, J.-P.; Le Fevre, O.; Macchetto, D.; MacKenty, J.; Madau, P.; Magliocchetti, M.; Maino, D.; Mandolesi, N.; Masetti, N.; McLure, R.; Mennella, A.; Meyer, M.; Mignoli, M.; Mobasher, B.; Molinari, E.; Morgante, G.; Morris, S.; Nicastro, L.; Oliva, E.; Padovani, P.; Palazzi, E.; Paresce, F.; Perez Garrido, A.; Pian, E.; Popa, L.; Postman, M.; Pozzetti, L.; Rayner, J.; Rebolo, R.; Renzini, A.; Röttgering, H.; Schinnerer, E.; Scodeggio, M.; Saisse, M.; Shanks, T.; Shapley, A.; Sharples, R.; Shea, H.; Silk, J.; Smail, I.; Spanó, P.; Steinacker, J.; Stringhetti, L.; Szalay, A.; Tresse, L.; Trifoglio, M.; Urry, M.; Valenziano, L.; Villa, F.; Villo Perez, I.; Walter, F.; Ward, M.; White, R.; White, S.; Wright, E.; Wyse, R.; Zamorani, G.; Zacchei, A.; Zeilinger, W. W.; Zerbi, F.

    2009-03-01

    We describe the scientific motivations, the mission concept and the instrumentation of SPACE, a class-M mission proposed for concept study at the first call of the ESA Cosmic-Vision 2015-2025 planning cycle. SPACE aims to produce the largest three-dimensional evolutionary map of the Universe over the past 10 billion years by taking near-IR spectra and measuring redshifts for more than half a billion galaxies at 0 < z < 2 down to AB~23 over 3 π sr of the sky. In addition, SPACE will also target a smaller sky field, performing a deep spectroscopic survey of millions of galaxies to AB~26 and at 2 < z < 10 +. These goals are unreachable with ground-based observations due to the ≈500 times higher sky background (see e.g. Aldering, LBNL report number LBNL-51157, 2001). To achieve the main science objectives, SPACE will use a 1.5 m diameter Ritchey-Chretien telescope equipped with a set of arrays of Digital Micro-mirror Devices covering a total field of view of 0.4 deg2, and will perform large-multiplexing multi-object spectroscopy (e.g. ≈6000 targets per pointing) at a spectral resolution of R~400 as well as diffraction-limited imaging with continuous coverage from 0.8 to 1.8 μm. Owing to the depth, redshift range, volume coverage and quality of its spectra, SPACE will reveal with unique sensitivity most of the fundamental cosmological signatures, including the power spectrum of density fluctuations and its turnover. SPACE will also place high accuracy constraints on the dark energy equation of state parameter and its evolution by measuring the baryonic acoustic oscillations imprinted when matter and radiation decoupled, the distance-luminosity relation of cosmological supernovae, the evolution of the cosmic expansion rate, the growth rate of cosmic large-scale structure, and high- z galaxy clusters. The datasets from the SPACE mission will represent a long lasting legacy for the whole astronomical community whose data will be mined for many years to come.

  14. Planck intermediate results. XLVIII. Disentangling Galactic dust emission and cosmic infrared background anisotropies

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Aghanim, N.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Ballardini, M.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Basak, S.; Benabed, K.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Burigana, C.; Calabrese, E.; Cardoso, J.-F.; Carron, J.; Chiang, H. C.; Colombo, L. P. L.; Comis, B.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; de Bernardis, P.; de Zotti, G.; Delabrouille, J.; Di Valentino, E.; Dickinson, C.; Diego, J. M.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Dusini, S.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Fantaye, Y.; Finelli, F.; Forastieri, F.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frolov, A.; Galeotta, S.; Galli, S.; Ganga, K.; Génova-Santos, R. T.; Gerbino, M.; Ghosh, T.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Helou, G.; Henrot-Versillé, S.; Herranz, D.; Hivon, E.; Huang, Z.; Jaffe, A. H.; Jones, W. C.; Keihänen, E.; Keskitalo, R.; Kiiveri, K.; Kisner, T. S.; Krachmalnicoff, N.; Kunz, M.; Kurki-Suonio, H.; Lamarre, J.-M.; Langer, M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Le Jeune, M.; Levrier, F.; Lilje, P. B.; Lilley, M.; Lindholm, V.; López-Caniego, M.; Ma, Y.-Z.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Matarrese, S.; Mauri, N.; McEwen, J. D.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Molinari, D.; Moneti, A.; Montier, L.; Morgante, G.; Moss, A.; Natoli, P.; Oxborrow, C. A.; Pagano, L.; Paoletti, D.; Patanchon, G.; Perdereau, O.; Perotto, L.; Pettorino, V.; Piacentini, F.; Plaszczynski, S.; Polastri, L.; Polenta, G.; Puget, J.-L.; Rachen, J. P.; Racine, B.; Reinecke, M.; Remazeilles, M.; Renzi, A.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Ruiz-Granados, B.; Salvati, L.; Sandri, M.; Savelainen, M.; Scott, D.; Sirignano, C.; Sirri, G.; Soler, J. D.; Spencer, L. D.; Suur-Uski, A.-S.; Tauber, J. A.; Tavagnacco, D.; Tenti, M.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Trombetti, T.; Valiviita, J.; Van Tent, F.; Vielva, P.; Villa, F.; Vittorio, N.; Wandelt, B. D.; Wehus, I. K.; Zacchei, A.; Zonca, A.

    2016-12-01

    Using the Planck 2015 data release (PR2) temperature maps, we separate Galactic thermal dust emission from cosmic infrared background (CIB) anisotropies. For this purpose, we implement a specifically tailored component-separation method, the so-called generalized needlet internal linear combination (GNILC) method, which uses spatial information (the angular powerspectra) to disentangle the Galactic dust emission and CIB anisotropies. We produce significantly improved all-sky maps of Planck thermal dust emission, with reduced CIB contamination, at 353, 545, and 857 GHz. By reducing the CIB contamination of the thermal dust maps, we provide more accurate estimates of the local dust temperature and dust spectral index over the sky with reduced dispersion, especially at high Galactic latitudes above b = ±20°. We find that the dust temperature is T = (19.4 ± 1.3) K and the dust spectral index is β = 1.6 ± 0.1 averaged over the whole sky, while T = (19.4 ± 1.5) K and β = 1.6 ± 0.2 on 21% of the sky at high latitudes. Moreover, subtracting the new CIB-removed thermal dust maps from the CMB-removed Planck maps gives access to the CIB anisotropies over 60% of the sky at Galactic latitudes |b| > 20°. Because they are a significant improvement over previous Planck products, the GNILC maps are recommended for thermal dust science. The new CIB maps can be regarded as indirect tracers of the dark matter and they are recommended for exploring cross-correlations with lensing and large-scale structure optical surveys. The reconstructed GNILC thermal dust and CIB maps are delivered as Planck products.

  15. Prospects for measuring cosmic microwave background spectral distortions in the presence of foregrounds

    NASA Astrophysics Data System (ADS)

    Abitbol, Maximilian H.; Chluba, Jens; Hill, J. Colin; Johnson, Bradley R.

    2017-10-01

    Measurements of cosmic microwave background (CMB) spectral distortions have profound implications for our understanding of physical processes taking place over a vast window in cosmological history. Foreground contamination is unavoidable in such measurements and detailed signal-foreground separation will be necessary to extract cosmological science. In this paper, we present Markov chain Monte Carlo based spectral distortion detection forecasts in the presence of Galactic and extragalactic foregrounds for a range of possible experimental configurations, focusing on the Primordial Inflation Explorer (PIXIE) as a fiducial concept. We consider modifications to the baseline PIXIE mission (operating ≃ 12 months in distortion mode), searching for optimal configurations using a Fisher approach. Using only spectral information, we forecast an extended PIXIE mission to detect the expected average non-relativistic and relativistic thermal Sunyaev-Zeldovich distortions at high significance (194σ and 11σ, respectively), even in the presence of foregrounds. The ΛCDM Silk damping μ-type distortion is not detected without additional modifications of the instrument or external data. Galactic synchrotron radiation is the most problematic source of contamination in this respect, an issue that could be mitigated by combining PIXIE data with future ground-based observations at low frequencies (ν ≲ 15-30 GHz). Assuming moderate external information on the synchrotron spectrum, we project an upper limit of |μ| < 3.6 × 10-7 (95 per cent c.l.), slightly more than one order of magnitude above the fiducial ΛCDM signal from the damping of small-scale primordial fluctuations, but a factor of ≃250 improvement over the current upper limit from COBE/Far Infrared Absolute Spectrophotometer. This limit could be further reduced to |μ| < 9.4 × 10-8 (95 per cent c.l.) with more optimistic assumptions about extra low-frequency information and would rule out many alternative inflation

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

    SciTech Connect

    Wu Fengquan; Chen Xuelei

    2010-10-15

    Using the covariant formalism developed in a companion paper [F.-Q. Wu, L. E. Qiang, X. Wang, and X. Chen, preceding Article, Phys. Rev. D 82, 083002 (2010)] (paper I), we derive observational constraints on the Brans-Dicke model in a flat Friedmann-Lemaitre-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 {omega} with a new parameter {zeta}=ln(1/{omega}+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 {zeta} or {omega}, but negative {zeta} or {omega} could not be constrained effectively. However, with additional large scale structure data, one could break the degeneracy at {zeta}<0. The 2{sigma} (95.5%) bound on {zeta} is -0.008 37<{zeta}<0.010 18 (corresponding to {omega}<-120.0 or {omega}>97.8). We also obtained constraints on G/G, the rate of change of G at present, as -1.75x10{sup -12} yr{sup -1}

  17. Planck intermediate results: XLVIII. Disentangling Galactic dust emission and cosmic infrared background anisotropies

    SciTech Connect

    Aghanim, N.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Ballardini, M.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Basak, S.; Benabed, K.; Bernard, J. -P.; Bersanelli, M.; Bielewicz, P.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Burigana, C.; Calabrese, E.; Cardoso, J. -F.; Carron, J.; Chiang, H. C.; Colombo, L. P. L.; Comis, B.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; de Bernardis, P.; de Zotti, G.; Delabrouille, J.; Di Valentino, E.; Dickinson, C.; Diego, J. M.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Dusini, S.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Fantaye, Y.; Finelli, F.; Forastieri, F.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frolov, A.; Galeotta, S.; Galli, S.; Ganga, K.; Génova-Santos, R. T.; Gerbino, M.; Ghosh, T.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Helou, G.; Henrot-Versillé, S.; Herranz, D.; Hivon, E.; Huang, Z.; Jaffe, A. H.; Jones, W. C.; Keihänen, E.; Keskitalo, R.; Kiiveri, K.; Kisner, T. S.; Krachmalnicoff, N.; Kunz, M.; Kurki-Suonio, H.; Lamarre, J. -M.; Langer, M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Le Jeune, M.; Levrier, F.; Lilje, P. B.; Lilley, M.; Lindholm, V.; López-Caniego, M.; Ma, Y. -Z.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Matarrese, S.; Mauri, N.; McEwen, J. D.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M. -A.; Molinari, D.; Moneti, A.; Montier, L.; Morgante, G.; Moss, A.; Natoli, P.; Oxborrow, C. A.; Pagano, L.; Paoletti, D.; Patanchon, G.; Perdereau, O.; Perotto, L.; Pettorino, V.; Piacentini, F.; Plaszczynski, S.; Polastri, L.; Polenta, G.; Puget, J. -L.; Rachen, J. P.; Racine, B.; Reinecke, M.; Remazeilles, M.; Renzi, A.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Ruiz-Granados, B.; Salvati, L.; Sandri, M.; Savelainen, M.; Scott, D.; Sirignano, C.; Sirri, G.; Soler, J. D.; Spencer, L. D.; Suur-Uski, A. -S.; Tauber, J. A.; Tavagnacco, D.; Tenti, M.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Trombetti, T.; Valiviita, J.; Van Tent, F.; Vielva, P.; Villa, F.; Vittorio, N.; Wandelt, B. D.; Wehus, I. K.; Zacchei, A.; Zonca, A.

    2016-12-12

    Using the Planck 2015 data release (PR2) temperature maps, we separate Galactic thermal dust emission from cosmic infrared background (CIB) anisotropies. For this purpose, we implement a specifically tailored component-separation method, the so-called generalized needlet internal linear combination (GNILC) method, which uses spatial information (the angular powerspectra) to disentangle the Galactic dust emission and CIB anisotropies. We produce significantly improved all-sky maps of Planck thermal dust emission, with reduced CIB contamination, at 353, 545, and 857 GHz. By reducing the CIB contamination of the thermal dust maps, we provide more accurate estimates of the local dust temperature and dust spectral index over the sky with reduced dispersion, especially at high Galactic latitudes above b = ±20°. We find that the dust temperature is T = (19.4 ± 1.3) K and the dust spectral index is β = 1.6 ± 0.1 averaged over the whole sky, while T = (19.4 ± 1.5) K and β = 1.6 ± 0.2 on 21% of the sky at high latitudes. Moreover, subtracting the new CIB-removed thermal dust maps from the CMB-removed Planck maps gives access to the CIB anisotropies over 60% of the sky at Galactic latitudes |b| > 20°. Because they are a significant improvement over previous Planck products, the GNILC maps are recommended for thermal dust science. The new CIB maps can be regarded as indirect tracers of the dark matter and they are recommended for exploring cross-correlations with lensing and large-scale structure optical surveys. The reconstructed GNILC thermal dust and CIB maps are delivered as Planck products.

  18. Planck intermediate results: XLVIII. Disentangling Galactic dust emission and cosmic infrared background anisotropies

    DOE PAGES

    Aghanim, N.; Ashdown, M.; Aumont, J.; ...

    2016-12-12

    Using the Planck 2015 data release (PR2) temperature maps, we separate Galactic thermal dust emission from cosmic infrared background (CIB) anisotropies. For this purpose, we implement a specifically tailored component-separation method, the so-called generalized needlet internal linear combination (GNILC) method, which uses spatial information (the angular powerspectra) to disentangle the Galactic dust emission and CIB anisotropies. We produce significantly improved all-sky maps of Planck thermal dust emission, with reduced CIB contamination, at 353, 545, and 857 GHz. By reducing the CIB contamination of the thermal dust maps, we provide more accurate estimates of the local dust temperature and dust spectralmore » index over the sky with reduced dispersion, especially at high Galactic latitudes above b = ±20°. We find that the dust temperature is T = (19.4 ± 1.3) K and the dust spectral index is β = 1.6 ± 0.1 averaged over the whole sky, while T = (19.4 ± 1.5) K and β = 1.6 ± 0.2 on 21% of the sky at high latitudes. Moreover, subtracting the new CIB-removed thermal dust maps from the CMB-removed Planck maps gives access to the CIB anisotropies over 60% of the sky at Galactic latitudes |b| > 20°. Because they are a significant improvement over previous Planck products, the GNILC maps are recommended for thermal dust science. The new CIB maps can be regarded as indirect tracers of the dark matter and they are recommended for exploring cross-correlations with lensing and large-scale structure optical surveys. The reconstructed GNILC thermal dust and CIB maps are delivered as Planck products.« less

  19. Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Dai, Wei-Ming; Guo, Zong-Kuan; Cai, Rong-Gen; Zhang, Yuan-Zhong

    2017-06-01

    We investigate constraints on Lorentz invariance violation in the neutrino sector from a joint analysis of big bang nucleosynthesis and the cosmic microwave background. The effect of Lorentz invariance violation during the epoch of big bang nucleosynthesis changes the predicted helium-4 abundance, which influences the power spectrum of the cosmic microwave background at the recombination epoch. In combination with the latest measurement of the primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave background anisotropies give a strong constraint on the deformation parameter since adding the primordial helium measurement breaks the degeneracy between the deformation parameter and the physical dark matter density.

  20. Imaging the Spatial Fluctuations in Cosmic IR Background from Reionization with CIBER

    NASA Astrophysics Data System (ADS)

    Frazer, Chris; Bock, J.; Cooray, A.; Kawada, M.; Kim, M.; Lee, D.; Levenson, L.; Matsumoto, T.; Matsumuura, S.; Mitchell-Wynne, K.; Renbarger, T.; Smidt, J.; Sullivan, I.; Arai, T.; Tsumura, K.; Wada, T.; Zemcov, M.

    2011-01-01

    The Cosmic Infrared Background Experiment (CIBER) is a rocket-born absolute photometry imaging and spectroscopy experiment optimized to detect unresolved infrared signatures of first-light galaxies that were present during reionization. The signatures from reionization are theorized to be dominant at the wavelengths upon which CIBER surveys. CIBER consists of two wide field imagers to measure the extragalactic background fluctuations in the H and I-Bands (1.6 and 0.9 microns respectively) of the cosmic infrared background (CIB) as well as two spectrometers designed to take measurements of the foreground zodiacal light and the absolute Extragalactic Background Light (EBL) spectrum They imagers are capable of examining high-redshift (z 10-20) CIB fluctuations which will facilitate in the study of surface densities of sources associated with reionization. Studies of galaxies with similar redshift parameters (z > 6) are largely unaccounted for. The spectrometer configuration consists of one low resolution spectrometer and one narrow band spectrometer. They are respectively designed to take measurements of the absolute Extragalactic Background Light (EBL) spectrum, and foreground zodiacal light. In this poster we present the specifications for both CIBER imagers and detail how the fluctuations from galaxies during reionization will be measured.

  1. 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.

  2. The Cosmic Infrared Background Experiment (CIBER): A Sounding Rocket Payload to Study the near Infrared Extragalactic Background Light

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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.

  3. 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.

  4. 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.

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

    PubMed

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

    2005-11-03

    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.

  6. 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.

  7. Compressed sensing reconstruction of a string signal from interferometric observations of the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Wiaux, Y.; Puy, G.; Vandergheynst, P.

    2010-03-01

    We propose an algorithm for the reconstruction of the signal induced by cosmic strings in the cosmic microwave background (CMB), from radio-interferometric data at arcminute resolution. Radio interferometry provides incomplete and noisy Fourier measurements of the string signal, which exhibits sparse or compressible magnitude of the gradient due to the Kaiser-Stebbins effect. In this context, the versatile framework of compressed sensing naturally applies for solving the corresponding inverse problem. Our algorithm notably takes advantage of a model of the prior statistical distribution of the signal fitted on the basis of realistic simulations. Enhanced performance relative to the standard CLEAN algorithm is demonstrated by simulated observations under noise conditions including primary and secondary CMB anisotropies.

  8. A minimal empirical model for the cosmic far-infrared background anisotropies

    NASA Astrophysics Data System (ADS)

    Wu, Hao-Yi; Doré, Olivier

    2017-01-01

    Cosmic far-infrared background (CFIRB) probes unresolved dusty star-forming galaxies across cosmic time and is complementary to ultraviolet and optical observations of galaxy evolution. In this work, we interpret the observed CFIRB anisotropies using an empirical model based on resolved galaxies in ultraviolet and optical surveys. Our model includes stellar mass functions, star-forming main sequence, and dust attenuation. We find that the commonly used linear Kennicutt relation between infrared luminosity and star-formation rate over-produces the observed CFIRB amplitudes. The observed CFIRB requires that low-mass galaxies have lower infrared luminosities than expected from the Kennicutt relation, implying that low-mass galaxies have lower dust content and weaker dust attenuation. Our results demonstrates that CFIRB not only provides a stringent consistency check for galaxy evolution models but also constrains the dust content of low-mass galaxies.

  9. Effects of electrically charged dark matter on cosmic microwave background anisotropies

    NASA Astrophysics Data System (ADS)

    Kamada, Ayuki; Kohri, Kazunori; Takahashi, Tomo; Yoshida, Naoki

    2017-01-01

    We examine the possibility that dark matter consists of charged massive particles (CHAMPs) in view of the cosmic microwave background (CMB) anisotropies. The evolution of cosmological perturbations of CHAMPs with other components is followed in a self-consistent manner, without assuming that CHAMPs and baryons are tightly coupled. We incorporate for the first time the "kinetic recoupling" of the Coulomb scattering, which is characteristic of heavy CHAMPs. By a direct comparison of the predicted CMB temperature/polarization autocorrelations in CHAMP models and the observed spectra in the Planck mission, we show that CHAMPs leave sizable effects on them if it is lighter than 1 011 GeV . Our result can be applicable to any CHAMP as long as its lifetime is much longer than the cosmic time at the recombination (˜4 ×1 05 yr ). An application to millicharged particles is also discussed.

  10. 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.

  11. Non-Gaussian effects in the cosmic microwave background from inflation

    NASA Astrophysics Data System (ADS)

    Gangui, Alejandro

    1994-09-01

    The presence of non-Gaussian features in the cosmic microwave background (CMB) radiation maps represents one of the most long-awaited clues in the search for the actual structure of primordial radiation, still needing confirmation. These features could shed some light on the nontrivial task of distinguishing the real souce of the primeval perturbations leading to large scale structure. One of the simplest non-Gaussian signals to search is the (dimensionless) skewness scrS. Explicit computations for scrS are presented in the frame of physically motivated inflationary models (natural, intermediate, and polynomial potential inflation) in the hope of finding values in agreement with estimated quantities from large angle scale (e.g., COBE DMR) maps. In all the cases considered the non-Gaussian effects turn out to lie below the level of theoretical uncertainty (cosmic variance). The possibility of unveiling the signal for scrS with multiple-field models is also discussed.

  12. Measurement of the cosmic optical background using the long range reconnaissance imager on New Horizons

    PubMed Central

    Zemcov, Michael; Immel, Poppy; Nguyen, Chi; Cooray, Asantha; Lisse, Carey M.; Poppe, Andrew R.

    2017-01-01

    The cosmic optical background is an important observable that constrains energy production in stars and more exotic physical processes in the universe, and provides a crucial cosmological benchmark against which to judge theories of structure formation. Measurement of the absolute brightness of this background is complicated by local foregrounds like the Earth's atmosphere and sunlight reflected from local interplanetary dust, and large discrepancies in the inferred brightness of the optical background have resulted. Observations from probes far from the Earth are not affected by these bright foregrounds. Here we analyse the data from the Long Range Reconnaissance Imager (LORRI) instrument on NASA's New Horizons mission acquired during cruise phase outside the orbit of Jupiter, and find a statistical upper limit on the optical background's brightness similar to the integrated light from galaxies. We conclude that a carefully performed survey with LORRI could yield uncertainties comparable to those from galaxy counting measurements. PMID:28397781

  13. A search for the dipole anisotropy of the Cosmic X ray background

    NASA Astrophysics Data System (ADS)

    Evans, Tom

    1992-05-01

    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 10-2 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.

  14. 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.

  15. Non-Gaussianity of the cosmic infrared background anisotropies - II. Predictions of the bispectrum and constraints forecast

    NASA Astrophysics Data System (ADS)

    Pénin, A.; Lacasa, F.; Aghanim, N.

    2014-03-01

    Using a full analytical computation of the bispectrum based on the halo model together with the halo occupation number, we derive the bispectrum of the cosmic infrared background (CIB) anisotropies that trace the clustering of dusty-star-forming galaxies. We focus our analysis on wavelengths in the far-infrared and the sub-millimeter typical of the Planck/HFI and Herschel/SPIRE instruments, 350, 550, 850 and 1380 μm. We explore the bispectrum behaviour as a function of several models of evolution of galaxies and show that it is strongly sensitive to that ingredient. Contrary to the power spectrum, the bispectrum, at the four wavelengths, seems dominated by low-redshift galaxies. Such a contribution can be hardly limited by applying low flux cuts. We also discuss the contributions of halo mass as a function of the redshift and the wavelength, recovering that each term is sensitive to a different mass range. Furthermore, we show that the CIB bispectrum is a strong contaminant of the cosmic microwave background bispectrum at 850 μm and higher. Finally, a Fisher analysis of the power spectrum, bispectrum alone and of the combination of both shows that degeneracies on the halo occupation distribution parameters are broken by including the bispectrum information, leading to tight constraints even when including foreground residuals.

  16. PROBING THE EPOCH OF PRE-REIONIZATION BY CROSS-CORRELATING COSMIC MICROWAVE AND INFRARED BACKGROUND ANISOTROPIES

    SciTech Connect

    Atrio-Barandela, F.; Kashlinsky, A. E-mail: Alexander.Kashlinsky@nasa.gov

    2014-12-20

    The epoch of first star formation and the state of the intergalactic medium (IGM) at that time are not directly observable with current telescopes. The radiation from those early sources is now part of the cosmic infrared background (CIB) and, as these sources ionize the gas around them, the IGM plasma would produce faint temperature anisotropies in the cosmic microwave background (CMB) via the thermal Sunyaev-Zeldovich (TSZ) effect. While these TSZ anisotropies are too faint to be detected, we show that the cross-correlation of maps of source-subtracted CIB fluctuations from Euclid, with suitably constructed microwave maps at different frequencies, can probe the physical state of the gas during reionization and test/constrain models of the early CIB sources. We identify the frequency-combined, CMB-subtracted microwave maps from space- and ground-based instruments to show that they can be cross-correlated with the forthcoming all-sky Euclid CIB maps to detect the cross-power at scales ∼5'-60' with signal-to-noise ratios (S/Ns) of up to S/N ∼ 4-8 depending on the contribution to the Thomson optical depth during those pre-reionization epochs (Δτ ≅ 0.05) and the temperature of the IGM (up to ∼10{sup 4} K). Such a measurement would offer a new window to explore the emergence and physical properties of these first light sources.

  17. Probing the Epoch of Pre-reionization by Cross-correlating Cosmic Microwave and Infrared Background Anisotropies

    NASA Astrophysics Data System (ADS)

    Atrio-Barandela, F.; Kashlinsky, A.

    2014-12-01

    The epoch of first star formation and the state of the intergalactic medium (IGM) at that time are not directly observable with current telescopes. The radiation from those early sources is now part of the cosmic infrared background (CIB) and, as these sources ionize the gas around them, the IGM plasma would produce faint temperature anisotropies in the cosmic microwave background (CMB) via the thermal Sunyaev-Zeldovich (TSZ) effect. While these TSZ anisotropies are too faint to be detected, we show that the cross-correlation of maps of source-subtracted CIB fluctuations from Euclid, with suitably constructed microwave maps at different frequencies, can probe the physical state of the gas during reionization and test/constrain models of the early CIB sources. We identify the frequency-combined, CMB-subtracted microwave maps from space- and ground-based instruments to show that they can be cross-correlated with the forthcoming all-sky Euclid CIB maps to detect the cross-power at scales ~5'-60' with signal-to-noise ratios (S/Ns) of up to S/N ~ 4-8 depending on the contribution to the Thomson optical depth during those pre-reionization epochs (Δτ ~= 0.05) and the temperature of the IGM (up to ~104 K). Such a measurement would offer a new window to explore the emergence and physical properties of these first light sources.

  18. Parameter constraints from weak-lensing tomography of galaxy shapes and cosmic microwave background fluctuations

    NASA Astrophysics Data System (ADS)

    Merkel, Philipp M.; Schäfer, Björn Malte

    2017-08-01

    Recently, it has been shown that cross-correlating cosmic microwave background (CMB) lensing and three-dimensional (3D) cosmic shear allows to considerably tighten cosmological parameter constraints. We investigate whether similar improvement can be achieved in a conventional tomographic setup. We present Fisher parameter forecasts for a Euclid-like galaxy survey in combination with different ongoing and forthcoming CMB experiments. In contrast to a fully 3D analysis, we find only marginal improvement. Assuming Planck-like CMB data, we show that including the full covariance of the combined CMB and cosmic shear data improves the dark energy figure of merit (FOM) by only 3 per cent. The marginalized error on the sum of neutrino masses is reduced at the same level. For a next generation CMB satellite mission such as Prism, the predicted improvement of the dark energy FOM amounts to approximately 25 per cent. Furthermore, we show that the small improvement is contrasted by an increased bias in the dark energy parameters when the intrinsic alignment of galaxies is not correctly accounted for in the full covariance matrix.

  19. Gravitational instabilities of the cosmic neutrino background with non-zero lepton number

    NASA Astrophysics Data System (ADS)

    Barrie, Neil D.; Kobakhidze, Archil

    2017-09-01

    We argue that a cosmic neutrino background that carries non-zero lepton charge develops gravitational instabilities. Fundamentally, these instabilities are related to the mixed gravity-lepton number anomaly. We have explicitly computed the gravitational Chern-Simons term which is generated quantum-mechanically in the effective action in the presence of a lepton number asymmetric neutrino background. The induced Chern-Simons term has a twofold effect: (i) gravitational waves propagating in such a neutrino background exhibit birefringent behaviour leading to an enhancement/suppression of the gravitational wave amplitudes depending on the polarisation, where the magnitude of this effect is related to the size of the lepton asymmetry; (ii) Negative energy graviton modes are induced in the high frequency regime, which leads to very fast vacuum decay producing, e.g., positive energy photons and negative energy gravitons. From the constraint on the present radiation energy density, we obtain an interesting bound on the lepton asymmetry of the universe.

  20. On Compton reflection in the sources of the cosmic X-ray background

    NASA Technical Reports Server (NTRS)

    Zdziarski, Andrzej A.; Zycki, Piotr T.; Svensson, Roland; Boldt, Elihu

    1993-01-01

    Consideration is given to recent models for the cosmic X-ray background that assume that it originates from unresolved AGN emitting spectra due to enhanced Compton reflection of a power-law photon spectrum incident on cold matter. The parameter space of the Compton reflection model is studied, and the allowed parameter space is found to be severely constrained by physical and cosmological effects. For an incident power-law energy index alpha is greater than about 1, the X-ray peak in the observed spectrum from a population of AGN is necessarily at an energy less than that of the observed peak. Two examples of improved fits to the X-ray background are shown. It is concluded that the Compton reflection models proposed to date do not provide a straightforward explanation of the X-ray background spectrum.

  1. 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.

  2. Build up and integration of the rocket-borne Cosmic Infrared Background ExpeRiment-2

    NASA Astrophysics Data System (ADS)

    Lanz, Alicia E.; Arai, Toshiaki; Battle, John; Bock, James; Cooray, Asantha R.; Hristov, Viktor; Kojima, Tomoya; Korngut, Phillip; Lee, Dae Hee; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Nguyen, Chi; Shirahata, Mai; Takahashi, Aoi; Tsumurai, Kohji; Wada, Takehiko; Wang, Shiang-Yu; Zemcov, Michael B.

    2017-01-01

    The Cosmic Infrared Background ExpeRiment, CIBER-2, is a near-infrared rocket-borne instrument designed to conduct comprehensive multi-band measurements of extragalactic background light anisotropy on arcsecond to degree angular scales. 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. CIBER-2 is designed to make measurements of the EBL anisotropy with the sensitivity, spectral range, and spectral resolution required to disentangle the contributions to the EBL from various sources throughout cosmic history.CIBER-2 consists of a 28.5 cm Cassegrain telescope assembly, imaging optics, and cryogenics mounted aboard a sounding rocket. Two dichroic beam-splitters spectrally subdivide the incident radiation into three optical paths, which are further subdivided in two wavelength bands per path, for a total of six observational wavelength bands that span the optical to the near-infrared and produce six 1.2 by 2.4 degree images recorded by three 2048 x 2048 HAWAII-2RG detector arrays. A small portion of each detector is also dedicated to absolute spectrophotometric imaging provided by a linear-variable filter. The instrument has several novel cryogenic mechanisms, a cryogenically-cooled pop-up baffle that extends during observations to provide radiative shielding and an electromagnetic cold shutter. We provide an overview of the instrument and current integration.

  3. 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.

  4. 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.

  5. Optimization of transition edge sensor arrays for cosmic microwave background observations with the south pole telescope

    DOE PAGES

    Ding, Junjia; Ade, P. A. R.; Anderson, A. J.; ...

    2016-12-15

    In this study, we describe the optimization of transition-edge-sensor (TES) detector arrays for the thirdgeneration camera for the South PoleTelescope.The camera,which contains ~16 000 detectors, will make high-angular-resolution maps of the temperature and polarization of the cosmic microwave background. Our key results are scatter in the transition temperature of Ti/Au TESs is reduced by fabricating the TESs on a thin Ti(5 nm)/Au(5 nm) buffer layer and the thermal conductivity of the legs that support our detector islands is dominated by the SiOx dielectric in the microstrip transmission lines that run along

  6. 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.

  7. Small non-Gaussianity and dipole asymmetry in the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Wang, Lingfei; Mazumdar, Anupam

    2013-07-01

    In this paper we provide a prescription for obtaining a small non-Gaussianity and the observed dipole asymmetry in the cosmic microwave background radiation. The observations inevitably lead to multifield inflationary dynamics, where each field can create positive or negative large non-Gaussianity, resulting in a fine cancellation but with an observable imprint on the hemispherical asymmetry. We discuss this possibility within a simple slow-roll scenario and find that it is hard to explain the observed dipole asymmetry. We briefly discuss some speculative scenarios where one can explain dipole asymmetry.

  8. A measurement of the spectrum of the cosmic background radiation from 1 to 3 millimeter wavelength

    NASA Technical Reports Server (NTRS)

    Bernstein, G. M.; Fischer, M. L.; Richards, P. L.; Peterson, J. B.; Timusk, T.

    1990-01-01

    The brightness temperature of the sky is measured in five bands from 1 to 3 mm using apparatus related to that of Woody and Richards (1981) and Peterson et al. (1985). Examination of the data reveals the presence of two previously unknown systematic effects which limit the accuracy of the measurements. Similar systematic effects are most likely present in the data obtained previously with this apparatus. Upper limits to the temperature of the cosmic background radiation are set in four bands; the most stringent is T(CBR) less than 2.88 K at 1.1 mm (95 percent CL).

  9. Measurements of the Cosmic Background Radiation Temperature at 3.3and 9.1 MM

    SciTech Connect

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

    1983-06-01

    The authors report the results of measurements of the cosmic background radiation temperature at wavelengths of 9.1 and 3.3 mm. The 9.1 mm result, T{sub CBR} = 2.87 {+-} 0.21 K, is in good agreement with previous results and those obtained at longer wavelengths during the same experiment. The 3.3 mm result, T{sub CBR} = 2.4 {+-} 1.0 K, is consistent with previous measurements, but has a large error due to uncertainty in the atmospheric correction.

  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. Measurements of the cosmic background radiation temperature at 6. 3 centimeters

    SciTech Connect

    Mandolesi, N.; Calzolari, P.; Cortiglioni, S.; Morigi, G.; Danese, L.

    1986-11-01

    New measurements of the cosmic background radiation (CBR) intensity at 4.75 GHz (6.3 cm), made as a part of a large experiment to measure the CBR spectrum between 2.5 and 90 GHz, are reported. The present result, T(CBR) = 2.70 + or - 0.07 K, agrees with, but is substantially more accurate than, that previously reported by Mandolesi et al. (1984). Careful new observations of the emission from the atmosphere and from the Galaxy are also presented and discussed. 17 references.

  12. PHYSICS OF OUR DAYS: Cosmic microwave background anisotropy data correlation in WMAP and Relikt-1 experiments

    NASA Astrophysics Data System (ADS)

    Skulachev, Dmitrii P.

    2010-07-01

    A comparison is made of cosmic microwave background anisotropy data obtained from the WMAP satellite in 2001 - 2006 and from the Relikt-1 satellite in 1983 - 1984. It is shown that low-temperature area found by Relikt-1 is the location of the 'coldest spot' of the WMAP radiomap. The mutual correlation of the two datasets is estimated and found to be positive for all sky regions surveyed. The conclusion is made that with the 98% probability, the Relikt-1 experiment had detected the same signal that was later identified by WMAP. A discussion is given of whether the Relikt-1 experiment parameters were chosen correctly.

  13. New microwave background constraints on the cosmic matter budget: trouble for nucleosynthesis?

    PubMed

    Tegmark; Zaldarriaga

    2000-09-11

    We compute the joint constraints on ten cosmological parameters from the latest cosmic microwave background measurements. The lack of a significant second acoustic peak in the new BOOMERANG and MAXIMA data favors models with more baryons than big bang nucleosynthesis predicts, almost independently of what prior information is included. The simplest flat inflation models with purely scalar scale-invariant fluctuations prefer a baryon density 0. 022

  14. Generating the cosmic microwave background power asymmetry with gN L

    NASA Astrophysics Data System (ADS)

    Kenton, Zachary; Mulryne, David J.; Thomas, Steven

    2015-07-01

    We consider a higher-order term in the δ N expansion for the cosmic microwave background power asymmetry generated by a superhorizon isocurvature field fluctuation. The term can generate the asymmetry without requiring a large value of fNL. Instead it produces a nonzero value of gNL. A combination of constraints leads to an allowed region in fNL-gNL space. To produce the asymmetry with this term without a large value of fNL we find that the isocurvature field needs to contribute less than the inflation towards the power spectrum of the curvature perturbation.

  15. Late Time Neutrino Masses, the LSND Experiment and the Cosmic Microwave Background

    SciTech Connect

    Chacko, Z.; Hall, Lawrence J.; Oliver, Steven J.; Perelstein, Maxim

    2004-05-07

    Models with low-scale breaking of global symmetries in the neutrino sector provide an alternative to the seesaw mechanism for understanding why neutrinos are light. Such models can easily incorporate light sterile neutrinos required by the LSND experiment. Furthermore, the constraints on the sterile neutrino properties from nucleosynthesis and large scale structure can be removed due to the non-conventional cosmological evolution of neutrino masses and densities. We present explicit, fully realistic supersymmetric models, and discuss the characteristic signatures predicted in the angular distributions of the cosmic microwave background.

  16. 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.; hide

    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

  17. Optimization of transition edge sensor arrays for cosmic microwave background observations with the south pole telescope

    DOE PAGES

    Ding, Junjia; Ade, P. A. R.; Anderson, A. J.; ...

    2016-12-15

    In this study, we describe the optimization of transition-edge-sensor (TES) detector arrays for the thirdgeneration camera for the South PoleTelescope.The camera,which contains ~16 000 detectors, will make high-angular-resolution maps of the temperature and polarization of the cosmic microwave background. Our key results are scatter in the transition temperature of Ti/Au TESs is reduced by fabricating the TESs on a thin Ti(5 nm)/Au(5 nm) buffer layer and the thermal conductivity of the legs that support our detector islands is dominated by the SiOx dielectric in the microstrip transmission lines that run along

  18. The Dark UNiverse Explorer (DUNE): proposal to ESA's cosmic vision

    NASA Astrophysics Data System (ADS)

    Refregier, A.

    2009-03-01

    The Dark UNiverse Explorer (DUNE) is a wide-field space imager whose primary goal is the study of dark energy and dark matter with unprecedented precision. For this purpose, DUNE is optimised for the measurement of weak gravitational lensing but will also provide complementary measurements of baryonic accoustic oscillations, cluster counts and the Integrated Sachs Wolfe effect. Immediate auxiliary goals concern the evolution of galaxies, to be studied with unequalled statistical power, the detailed structure of the Milky Way and nearby galaxies, and the demographics of Earth-mass planets. DUNE is an Medium-class mission which makes use of readily available components, heritage from other missions, and synergy with ground based facilities to minimise cost and risks. The payload consists of a 1.2 m telescope with a combined visible/NIR field-of-view of 1 deg2. DUNE will carry out an all-sky survey, ranging from 550 to 1600 nm, in one visible and three NIR bands which will form a unique legacy for astronomy. DUNE will yield major advances in a broad range of fields in astrophysics including fundamental cosmology, galaxy evolution, and extrasolar planet search. DUNE was recently selected by ESA as one of the mission concepts to be studied in its Cosmic Vision programme.

  19. Exploring Evidence for Cosmic Ray Acceleration in Westerlund 1

    NASA Astrophysics Data System (ADS)

    Shipp, Nora; Brandt, T. J.; Fermi LAT Collaboration

    2015-01-01

    Westerlund 1 (Wd 1) is a massive stellar cluster located within the Galaxy at a distance of ~5 kpc from the Earth. The cluster is thought to be a site of significant Galactic cosmic ray acceleration. Further insight into this possibility can be gained through the study of gamma-ray emission from the cluster. The High Energy Stereoscopic System (HESS) has detected an extended TeV source coincident with Wd 1 and now the Fermi Large Area Telescope (LAT) has detected extended GeV gamma-ray emission from the region. Examining this data allows for a more precise understanding of the emission originating from Wd 1 itself. We modeled the source as a 2-dimensional gaussian and, considering the region within 15º of the nominal position of Wd 1, determined the maximum likelihood spectrum, position, and extension. It is clear that a significant, extended GeV source is present and may be associated with the stellar cluster. We will additionally explore any energy dependence in the source's morphology to understand implications, particularly for the source association. Continued examination of the emission originating from the Wd 1 region will reveal details about the acceleration and composition of particles, both leptons and hadrons, originating in the region.

  20. 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.

  1. Detecting chiral gravity with the pure pseudospectrum reconstruction of the cosmic microwave background polarized anisotropies

    NASA Astrophysics Data System (ADS)

    Ferté, A.; Grain, J.

    2014-05-01

    We consider the possible detection of parity violation at the linear level in gravity using polarized anisotropies of the cosmic microwave background. Since such a parity violation would lead to nonzero temperature-B modes (TB) and E modes-B modes (EB) correlations, this makes those odd-parity angular power spectra a potential probe of parity violation in the gravitational sector. These spectra are modeled incorporating the impact of lensing and we explore their possible detection in the context of small-scale (balloon-borne or ground-based) experiments and a future satellite mission dedicated to B-mode detection. We assess the statistical uncertainties on their reconstruction using mode counting and a (more realistic) pure pseudospectrum estimator approach. Those uncertainties are then translated into constraints on the level of parity asymmetry. We found that detecting chiral gravity is impossible for ongoing small-scale experiments. However, for a satellite-like mission, a parity asymmetry of 50% could be detected at 68% of confidence level (C.L.) (at least, depending on the value of the tensor-to-scalar ratio), and a parity asymmetry of 100% is measurable with at least a confidence level of 95%. We also assess the impact of a possible miscalibration of the orientation of the polarized detectors, leading to spurious TB and EB cross correlations. We show that in the context of pseudospectrum estimation of the angular power spectra, self calibration of this angle could significantly reduce the statistical significance of the measured level of parity asymmetry (by e.g. a factor ˜2.4 for a miscalibration angle of 1 degree). For chiral gravity and assuming a satellite mission dedicated to primordial B mode, a nondetection of the TB and EB correlation would translate into an upper bound on parity violation of 39% at 95% confidence level for a tensor-to-scalar ratio of 0.2, excluding values of the (imaginary) Barbero-Immirzi parameter comprised between 0.2 and 4.9 at

  2. 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.

  3. 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.

  4. A two-fluid approximation for calculating the cosmic microwave background anisotropies

    NASA Technical Reports Server (NTRS)

    Seljak, Uros

    1994-01-01

    We present a simplified treatment for calculating the cosmic microwave background anisotropy power spectrum in adiabatic models. It consists of solving for the evolution of a two-fluid model until the epoch of recombination and then integrating over the sources to obtain the cosmic microwave background (CMB) anisotropy power spectrum. The approximation is useful both for a physical understanding of CMB anisotropies as well as for a quantitative analysis of cosmological models. Comparison with exact calculations shows that the accuracy is typically 10%-20% over a large range of angles and cosmological models, including those with curvature and cosmological constant. Using this approximation we investigate the dependence of the CMB anisotropy on the cosmological parameters. We identify six dimensionless parameters that uniquely determine the anisotropy power spectrum within our approximation. CMB experiments on different angular scales could in principle provide information on all these parameters. In particular, mapping of the Doppler peaks would allow an independent determination of baryon mass density, matter mass density, and the Hubble constant.

  5. 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.

  6. First detection of cosmic microwave background lensing and Lyman-α forest bispectrum

    NASA Astrophysics Data System (ADS)

    Doux, Cyrille; Schaan, Emmanuel; Aubourg, Eric; Ganga, Ken; Lee, Khee-Gan; Spergel, David N.; Tréguer, Julien

    2016-11-01

    We present the first detection of a correlation between the Lyman-α forest and cosmic microwave background gravitational lensing. For each Lyman-α forest in SDSS-III/BOSS DR12, we correlate the one-dimensional power spectrum with the cosmic microwave background lensing convergence on the same line of sight from Planck. This measurement constitutes a position-dependent power spectrum, or a squeezed bispectrum, and quantifies the nonlinear response of the Lyman-α forest power spectrum to a large-scale overdensity. The signal is measured at 5 σ and is consistent with the expectation of the standard Λ CDM cosmological model. We measure the linear bias of the Lyman-α forest with respect to the dark matter distribution and constrain a combination of nonlinear terms including the nonlinear bias. This new observable provides a consistency check for the Lyman-α forest as a large-scale structure probe and tests our understanding of the relation between intergalactic gas and dark matter. In the future, it could be used to test hydrodynamical simulations and calibrate the relation between the Lyman-α forest and dark matter.

  7. 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.

  8. 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.

  9. Interstellar cyanogen and the temperature of the cosmic microwave background radiation

    NASA Technical Reports Server (NTRS)

    Roth, Katherine C.; Meyer, David M.; Hawkins, Isabel

    1993-01-01

    We present the results of a recently completed effort to determine the amount of CN rotational excitation in five diffuse interstellar clouds for the purpose of accurately measuring the temperature of the cosmic microwave background radiation (CMBR). In addition, we report a new detection of emission from the strongest hyperfine component of the 2.64 mm CN rotational transition (N = 1-0) in the direction toward HD 21483. We have used this result in combination with existing emission measurements toward our other stars to correct for local excitation effects within diffuse clouds which raise the measured CN rotational temperature above that of the CMBR. After making this correction, we find a weighted mean value of T(CMBR) = 2.729 (+0.023, -0.031) K. This temperature is in excellent agreement with the new COBE measurement of 2.726 +/- 0.010 K (Mather et al., 1993). Our result, which samples the CMBR far from the near-Earth environment, attests to the accuracy of the COBE measurement and reaffirms the cosmic nature of this background radiation. From the observed agreement between our CMBR temperature and the COBE result, we conclude that corrections for local CN excitation based on millimeter emission measurements provide an accurate adjustment to the measured rotational excitation.

  10. 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.

  11. Empirical Constraints on the Cosmic Infrared Background Using Near-Infrared DIRBE Data

    NASA Technical Reports Server (NTRS)

    Arendt, Richard G.

    2000-01-01

    Empirical models for emission from stars and the ISM are subtracted from the zodiacal-light-subtracted DIRBE 3.5 pm emission. Because the models are contaminated by unknown levels of the CM at other near-IR wavelength, the residual is not simply the 3.5 Jim Cosmic IR Background, but a linear combination of the background levels at several wavelengths. In spite of this, the residual can be used to place limits on the near-IR CIB intensity if its spectral shape is assumed. Additionally, the residual level is shown to be more nearly isotropic than previous estimates over a much larger fraction of the sky. An excellent correlation of near-IR and far-IR ISM emission provides evidence of the high accuracy of the brighter stellar emission model. The possibility that any residual emission is zodiacal in nature is discussed.

  12. 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.

  13. Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries

    NASA Astrophysics Data System (ADS)

    Madau, Piero; Fragos, Tassos

    2017-05-01

    We compute the expected X-ray diffuse background and radiative feedback on the intergalactic medium (IGM) from X-ray binaries prior to and during the epoch of reionization. The cosmic evolution of compact binaries is followed using a population synthesis technique that treats separately neutron stars and black hole binaries in different spectral states and is calibrated to reproduce the observed X-ray properties of galaxies at z ≲ 4. Together with an updated empirical determination of the cosmic history of star formation, recent modeling of the stellar mass-metallicity relation, and a scheme for absorption by the IGM that accounts for the presence of ionized H ii bubbles during the epoch of reionization, our detailed calculations provide refined predictions of the X-ray volume emissivity and filtered radiation background from “normal” galaxies at z ≳ 6. Radiative transfer effects modulate the background spectrum, which shows a characteristic peak between 1 and 2 keV. Because of the energy dependence of photoabsorption, soft X-ray photons are produced by local sources, while more energetic radiation arrives unattenuated from larger cosmological volumes. While the filtering of X-ray radiation through the IGM slightly increases the mean excess energy per photoionization, it also weakens the radiation intensity below 1 keV, lowering the mean photoionization and heating rates. Numerical integration of the rate and energy equations shows that the contribution of X-ray binaries to the ionization of the bulk IGM is negligible, with the electron fraction never exceeding 1%. Direct He i photoionizations are the main source of IGM heating, and the temperature of the largely neutral medium in between H ii cavities increases above the temperature of the cosmic microwave background (CMB) only at z ≲ 10, when the volume filling factor of H ii bubbles is already ≳0.1. Therefore, in this scenario, it is only at relatively late epochs that neutral intergalactic hydrogen

  14. The extragalactic background light revisited and the cosmic photon-photon opacity

    NASA Astrophysics Data System (ADS)

    Franceschini, Alberto; Rodighiero, Giulia

    2017-07-01

    Context. In addition to its relevant astrophysical and cosmological significance, the extragalactic background light (EBL) is a fundamental source of opacity for cosmic high energy photons, as well as a limitation for the propagation of high-energy particles in the Universe. Aims: We review our previously published determinations of the EBL photon density in the Universe and its evolution with cosmic time, in the light of recent surveys of IR sources at long wavelengths. Methods: We exploit deep survey observations by the Herschel Space Observatory and the Spitzer telescope, matched to optical and near-IR photometric and spectroscopic data, to re-estimate number counts and luminosity functions longwards of a few microns, and the contribution of resolved sources to the EBL. Results: These new data indicate slightly lower photon densities in the mid- and far-infrared and sub-millimeter compared to previous determinations. This implies slightly lower cosmic opacity for photon-photon interactions. Conclusions: The new data do not modify previously published EBL modeling in the UV-optical and near-IR up to several microns, while reducing the photon density at longer wavelengths. This improved model of the EBL alleviates some tension that had emerged in the interpretation of the highest-energy TeV observations of local blazars, reducing the case for new physics beyond the standard model (like violations of the Lorenz Invariance, LIV, at the highest particle energies), or for exotic astrophysics, that had sometimes been called for to explain it. Applications of this improved EBL model on current data are considered, as well as perspectives for future instrumentation, the Cherenkov Telescope Array (CTA) in particular.

  15. Cosmic ray contribution in extragalactic background gamma-ray emission at an energy of 0.1 TeV

    NASA Astrophysics Data System (ADS)

    Uryson, Anna

    2017-06-01

    We estimate the intensity of gamma-quanta at the energy 0.1 TeV that is generated in extragalactic space in interactions of ultra-high energy cosmic rays with the cosmic background emission. Energy of 0.1 TeV is chosen because the Universe is mostly transparent for these quanta. In the paper three types of cosmic ray sources are analyzed: objects with red shifts up to z = 1.1 having monoenergetic particle spectra, E = 1021 eV; the same objects with exponential particle spectra; objects with red shifts 0 < z ≤ 0.0092 i.e. located at distances less than ≈ 50 Mpc, also with exponential particle spectra. It is found that the cosmic ray contribution in extragalactic background emission at 0.1 TeV ranges from f ≤ 10-4 to f ≈ 0.1 depending on the source characteristics. Thus the cosmic ray contribution in extragalactic background emission can be used for studying cosmic ray sources.

  16. Effect of Primordial Black Holes on the Cosmic Microwave Background and Cosmological Parameter Estimates

    NASA Astrophysics Data System (ADS)

    Ricotti, Massimo; Ostriker, Jeremiah; Mack, Katherine

    2017-01-01

    We investigate the effect of nonevaporating primordial black holes (PBHs) on the ionization and thermal history of the universe. X-rays emitted by gas accretion onto PBHs modify the cosmic recombination history, producing measurable effects on the spectrum and anisotropies of the cosmic microwave background (CMB). Using the third-year WMAP data and COBE FIRAS data we improve existing upper limits on the abundance of PBHs with masses > 0 . 1 M⊙ by several orders of magnitude, thus ruling out PBHs in this mass range as a significant component of the dark matter. Fitting WMAP/Planck data with cosmological models that do not allow for nonstandard recombination histories, as produced by PBHs or other early energy sources, leads to underestimating the best-fit values of the amplitude of linear density fluctuations (σ8) and the scalar spectral index (ns). We find that a fraction > 0 . 1 % - 1 % of the dark matter in 30 M⊙ PBHs produces CMB spectral distortions at a level detectable by FIRAS. Therefore, even allowing for possible modeling uncertainties, future missions measuring CMB spectral distortions will detect the imprint of dark matter if it's composed of 30 M⊙ PBHs, as suggested to interpret recent LIGO results.

  17. 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.; hide

    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.

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

    SciTech Connect

    Naidoo, Krishna; Benoit-Levy, Aurelien; Lahav, Ofer

    2016-03-20

    Understanding the observed Cold Spot (CS) (temperature of ~ -150 mu K at its centre) on the Cosmic Microwave Background (CMB) 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 mu K. In this model the central CS temperature lies at ~ 2σ but fails to explain the CS hot ring. An alternative multi-void 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 multi-void scenarios) are removed. Furthermore, the CS tension with the LCDM model can be reduced dramatically for an array of temperature profiles smaller than the CS itself.

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

    DOE PAGES

    Naidoo, Krishna; Benoit-Levy, Aurelien; Lahav, Ofer

    2016-03-20

    Understanding the observed Cold Spot (CS) (temperature of ~ -150 mu K at its centre) on the Cosmic Microwave Background (CMB) 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 mu K.more » In this model the central CS temperature lies at ~ 2σ but fails to explain the CS hot ring. An alternative multi-void 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 multi-void scenarios) are removed. Furthermore, the CS tension with the LCDM model can be reduced dramatically for an array of temperature profiles smaller than the CS itself.« less

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Initial state effects on the cosmic microwave background and trans-Planckian physics

    NASA Astrophysics Data System (ADS)

    Goldstein, Kevin; Lowe, David A.

    2003-03-01

    There exists a one complex parameter family of de Sitter invariant vacua, known as α vacua. In the context of slow roll inflation, we show that all but the Bunch-Davies vacuum generates unacceptable production of high energy particles at the end of inflation. As a simple model for the effects of trans-Planckian physics, we go on to consider non de Sitter invariant vacua obtained by patching modes in the Bunch-Davies vacuum above some momentum scale Mc, with modes in an α vacuum below Mc. Choosing Mc near the Planck scale MPl, we find acceptable levels of hard particle production, and corrections to the cosmic microwave perturbations at the level of HMPl/M2c, where H is the Hubble parameter during inflation. More general initial states of this type with H≪Mc≪MPl can give corrections to the spectrum of cosmic microwave background perturbations at order 1. The parameter characterizing the α vacuum during inflation is a new cosmological observable.

  5. Cosmic constraint on massive neutrinos in viable f( R) gravity with producing Λ CDM background expansion

    NASA Astrophysics Data System (ADS)

    Lu, Jianbo; Liu, Molin; Wu, Yabo; Wang, Yan; Yang, Weiqiang

    2016-12-01

    Tensions between several cosmic observations were found recently, such as the inconsistent values of H0 (or σ 8) were indicated by the different cosmic observations. Introducing the massive neutrinos in Λ CDM could potentially solve the tensions. Viable f( R) gravity producing Λ CDM background expansion with massive neutrinos is investigated in this paper. We fit the current observational data: Planck-2015 CMB, RSD, BAO, and SNIa to constrain the mass of neutrinos in viable f( R) theory. The constraint results at 95% confidence level are: Σ m_ν <0.202 eV for the active-neutrino case, m_{ν , sterile}^eff<0.757 eV with N_eff<3.22 for the sterile neutrino case. For the effects due to the mass of the neutrinos, the constraint results on model parameter at 95% confidence level become f_{R0}× 10^{-6}> -1.89 and f_{R0}× 10^{-6}> -2.02 for two cases, respectively. It is also shown that the fitting values of several parameters much depend on the neutrino properties, such as the cold dark matter density, the cosmological quantities at matter-radiation equality, the neutrino density and the fraction of baryonic mass in helium. Finally, the constraint result shows that the tension between direct and CMB measurements of H_0 gets slightly weaker in the viable f( R) model than that in the base Λ CDM model.

  6. Inflation 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.; 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 5σ 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.

  7. A New Era in Extragalactic Background Light Measurements: The Cosmic History of Accretion, Nucleosynthesis and Reionization

    NASA Astrophysics Data System (ADS)

    Cooray, Asantha; Amblard, Alexandre; Beichman, Charles; Benford, Dominic; Bernstein, Rebecca; Bock, James J.; Brodwin, Mark; Bromm, Volker; Cen, Renyue; Chary, Ranga R.; Devlin, Mark; Dolch, Timothy; Dole, Herve; Dwek, Eli; Elbaz, David; ' Fall, Michael; Fazio, Giovanni; Ferguson, Henry; Furlanetto, Steven; Gardner, Jonathan; Giavalisco, Mauro; Gilmore, Rudy; Gnedin, Nickolay; Gonzalez, Anthony; Haiman, Zoltan; Kelsall, Thomas; Komatsu, Eiichiro; Lagache, Guilaine; Levenson, Louis R.; Loeb, Avi; Badau, Piero; Mather, John C.; Matsumoto, Toshio; Mattila, Kalevi; Moseley, Marvey; Moustakas, Leonidas; Oh, S. Peng; Petro, Larry; Primack, Joel; Reach, William; Renbarger, Tom; Shapiro, Paul; Stern, Daniel; Sullivan, Ian; Venkatesan, Aparna; Werner, Michael; Windhorst, Rogier; Wright, Edward L.; Zemcov, Michael

    (Brief Summary) What is the total radiative content of the Universe since the epoch of recombination? The extragalactic background light (EBL) spectrum captures the redshifted energy released from the first stellar objects, protogalaxies, and galaxies throughout cosmic history. Yet, we have not determined the brightness of the extragalactic sky from UV/optical to far-infrared wavelengths with sufficient accuracy to establish the radiative content of the Universe to better than an order of magnitude. Among many science topics, an accurate measurement of the EBL spectrum from optical to far-IR wavelengths, will address: What is the total energy released by stellar nucleosynthesis over cosmic history? Was significant energy released by non-stellar processes? Is there a diffuse component to the EBL anywhere from optical to sub-millimeter? When did first stars appear and how luminous was the reionization epoch? Absolute optical to mid-IR EBL spectrum to an astrophysically interesting accuracy can be established by wide field imagingat a distance of 5 AU or above the ecliptic plane where the zodiacal foreground is reduced by more than two orders of magnitude.

  8. Gravitational radiation from cosmic (super)strings: Bursts, stochastic background, and observational windows

    SciTech Connect

    Damour, Thibault; Vilenkin, Alexander

    2005-03-15

    The gravitational wave (GW) signals emitted by a network of cosmic strings are reexamined in view of the possible formation of a network of cosmic superstrings at the end of brane inflation. The reconnection probability p of intersecting fundamental or Dirichlet strings might be much smaller than 1, and the properties of the resulting string network may differ significantly from those of ordinary strings (which have p=1). In addition, it has been recently suggested that the typical length of newly formed loops may differ by a factor {epsilon}<<1 from its standard estimate. Here, we analyze the effects of the two parameters p and {epsilon} on the GW signatures of strings. We consider both the GW bursts emitted from cusps of oscillating string loops, which have been suggested as candidate sources for the LIGO/VIRGO and LISA interferometers, and the stochastic GW background, which may be detectable by pulsar-timing observations. In both cases we find that previously obtained results are quite robust, at least when the loop sizes are not suppressed by many orders of magnitude relative to the standard scenario. We urge pulsar observers to reanalyze a recently obtained 17-yr combined data set to see whether the large scatter exhibited by a fraction of the data might be due to a transient GW burst activity of some sort, e.g., to a near cusp event.

  9. 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.

  10. 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.

  11. The Cosmic Infrared Background Experiment (CIBER): The Wide-field Imagers

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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° × 2° field of view to measure fluctuations over the predicted peak of the spatial power spectrum at 10 arcmin, and 7'' × 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 Δλ/λ ~ 0.5 bandpasses centered at 1.1 μm and 1.6 μm 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.

  12. 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.

  13. Badhwar-O'Neil 2007 Galactic Cosmic Ray (GCR) Model Using Advanced Composition Explorer (ACE) Measurements for Solar Cycle 23

    NASA Technical Reports Server (NTRS)

    ONeill, P. M.

    2007-01-01

    Advanced Composition Explorer (ACE) satellite measurements of the galactic cosmic ray flux and correlation with the Climax Neutron Monitor count over Solar Cycle 23 are used to update the Badhwar O'Neill Galactic Cosmic Ray (GCR) model.

  14. Test of the Einstein equivalence principle with spectral distortions in the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Arai, Shun; Nitta, Daisuke; Tashiro, Hiroyuki

    2016-12-01

    The Einstein equivalence principle (EEP) can be verified by the measurement of the spectral distortions of the cosmic microwave background (CMB). One of the consequences of the EEP on cosmological scales is the energy independency of the cosmological redshift effect. We propose a new test of the energy independency of the redshift effect by the measurement of the spectral distortion of CMB. In general relativity, the energy independency of the redshift effect is ensured by the Friedmann-Robertson-Walker (FRW) metric which does not depend on energy. We show that the CMB spectral distortions arise when the FRW metric has the energy dependence. Assuming the simple energy-dependent form of the FRW metric, we evaluate the CMB distortions. From the COBE/FIRAS bound, we find that the deviation degree from the EEP is, at least, less than 10-5 at the CMB energy scales.

  15. Effect of time variation in the Higgs vacuum expectation value on the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Kujat, Jens; Scherrer, Robert J.

    2000-07-01

    A time variation in the Higgs vacuum expectation value alters the electron mass and thereby changes the ionization history of the universe. This change produces a measurable imprint on the pattern of cosmic microwave background (CMB) fluctuations. The nuclear masses and nuclear binding energies, as well as the Fermi coupling constant, are also altered, with negligible impact on the CMB. We calculate the changes in the spectrum of the CMB fluctuations as a function of the change in the electron mass me. We find that future CMB experiments could be sensitive to \\|Δme/me\\|~\\|ΔGF/GF\\|~10-2-10-3. However, we also show that a change in me is nearly, but not exactly, degenerate with a change in the fine-structure constant α. If both me and α are time varying, the corresponding CMB limits are much weaker, particularly for l<1000.

  16. Low-Resolution Near-infrared Stellar Spectra Observed by the Cosmic Infrared Background Experiment (CIBER)

    NASA Astrophysics Data System (ADS)

    Kim, Min Gyu; Lee, Hyung Mok; Arai, Toshiaki; Bock, James; Cooray, Asantha; Jeong, Woong-Seob; Kim, Seong Jin; Korngut, Phillip; Lanz, Alicia; Lee, Dae Hee; Lee, Myung Gyoon; Matsumoto, Toshio; Matsuura, Shuji; Nam, Uk Won; Onishi, Yosuke; Shirahata, Mai; Smidt, Joseph; Tsumura, Kohji; Yamamura, Issei; Zemcov, Michael

    2017-02-01

    We present near-infrared (0.8-1.8 μm) spectra of 105 bright ({m}J < 10) stars observed with the low-resolution spectrometer on the rocket-borne Cosmic Infrared Background Experiment. As our observations are performed above the Earth's atmosphere, our spectra are free from telluric contamination, which makes them a unique resource for near-infrared spectral calibration. Two-Micron All-Sky Survey photometry information is used to identify cross-matched stars after reduction and extraction of the spectra. We identify the spectral types of the observed stars by comparing them with spectral templates from the Infrared Telescope Facility library. All the observed spectra are consistent with late F to M stellar spectral types, and we identify various infrared absorption lines.

  17. 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.

  18. Antenna-Coupled Bolometer Arrays for Measurement of the Cosmic Microwave Background Polarization

    NASA Astrophysics Data System (ADS)

    Myers, M. J.; Arnold, K.; Ade, P.; Engargiola, G.; Holzapfel, W.; Lee, A. T.; Meng, X.; O'Brient, R.; Richards, P. L.; Spieler, H.; Tran, H. T.

    2008-04-01

    We are building antenna-coupled Transition Edge Sensor bolometer arrays to measure the polarization of the cosmic microwave background. 217 GHz prototype pixels have previously been characterized and showed promising performance (Myers et al. in Appl. Phys. Lett. 86:114103, [2005]). Our design uses a double slot dipole antenna and an integrated microstrip band defining filter. New devices have been tested which include on-chip test structures to improve our understanding of detector performance and guide future development. In parallel with this, large arrays of bolometers based on the prototype pixel design have also been constructed. The array pixels are a heterogeneous mixture of single band pixels at 90 GHz, 150 GHz, and 220 GHz and now incorporate dual-polarization antennas (Chattopadhyay and Zmuidzinas in IEEE Trans. Antennas Propag. 46:736, [1998]). Preliminary results from optical testing of array pixels are presented. These bolometer arrays will be used in the upcoming CMB polarization experiment P olarbear.

  19. Joint cosmic microwave background and weak lensing analysis: constraints on cosmological parameters.

    PubMed

    Contaldi, Carlo R; Hoekstra, Henk; Lewis, Antony

    2003-06-06

    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.

  20. Cosmology from MAXIMA-1, BOOMERANG, and COBE DMR cosmic microwave background observations.

    PubMed

    Jaffe, A H; Ade, P A; Balbi, A; Bock, J J; Bond, J R; Borrill, J; Boscaleri, A; Coble, K; Crill, B P; de Bernardis, P; Farese, P; Ferreira, P G; Ganga, K; Giacometti, M; Hanany, S; Hivon, E; Hristov, V V; Iacoangeli, A; Lange, A E; Lee, A T; Martinis, L; Masi, S; Mauskopf, P D; Melchiorri, A; Montroy, T; Netterfield, C B; Oh, S; Pascale, E; Piacentini, F; Pogosyan, D; Prunet, S; Rabii, B; Rao, S; Richards, P L; Romeo, G; Ruhl, J E; Scaramuzzi, F; Sforna, D; Smoot, G F; Stompor, R; Winant, C D; Wu, J H

    2001-04-16

    Recent results from BOOMERANG-98 and MAXIMA-1, taken together with COBE DMR, provide consistent and high signal-to-noise measurements of the cosmic microwave background power spectrum at spherical harmonic multipole bands over 2

  1. Interpretation of the cosmic microwave background radiation anisotropy detected by the COBE Differential Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Wright, E. L.; Meyer, S. S.; Bennett, C. L.; Boggess, N. W.; Cheng, E. S.; Hauser, M. G.; Kogut, A.; Lineweaver, C.; Mather, J. C.; Smoot, G. F.

    1992-01-01

    The large-scale cosmic background anisotropy detected by the COBE Differential Microwave Radiometer (DMR) instrument is compared to the sensitive previous measurements on various angular scales, and to the predictions of a wide variety of models of structure formation driven by gravitational instability. The observed anisotropy is consistent with all previously measured upper limits and with a number of dynamical models of structure formation. For example, the data agree with an unbiased cold dark matter (CDM) model with H0 = 50 km/s Mpc and Delta-M/M = 1 in a 16 Mpc radius sphere. Other models, such as CDM plus massive neutrinos (hot dark matter (HDM)), or CDM with a nonzero cosmological constant are also consistent with the COBE detection and can provide the extra power seen on 5-10,000 km/s scales.

  2. Galactic Plane image sharpness as a check on cosmic microwave background mapmaking

    NASA Astrophysics Data System (ADS)

    Roukema, B. F.

    2010-12-01

    The largest uncollapsed inhomogeneity in the observable Universe is statistically represented in the quadrupole signal of the cosmic microwave background (CMB) sky maps as observed by the Wilkinson Microwave Anisotropy Probe (WMAP). The constant temporal offset of -25.6~ms between the timestamps of the spacecraft attitude and observational data records in the time-ordered data (TOD) of the WMAP observations was suspected to imply that previously derived all-sky CMB maps are erroneous, and that the quadrupole is in large part an artefact. The optimal focussing of bright objects in the Galactic Plane plays a key role in showing that no error occurred at the step of mapmaking from the calibrated TOD. Instead, the error had an effect when the uncalibrated TOD were calibrated. Estimates of the high-latitude quadrupole based on the wrongly calibrated WMAP maps are overestimated by about 15--60%.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. The cosmic microwave background radiation and the dog in the night

    NASA Astrophysics Data System (ADS)

    Partridge, R. B.

    The spectrum and angular distribution of the cosmic microwave background radiation (CMBR) are characterized, summarizing the results of recent observations. The emphasis is on null experiments which have established upper limits on anisotropies and spectral distortion. The benefits and pitfalls of null experiments are recalled; the generally observed isotropy of the CMBR and the possible ways anisotropy could be introduced are discussed; and data from searches for anisotropy on arcmin, degree, and arcsec scales are presented in tables and graphs and analyzed in detail. The observed CMBR spectrum is shown to be generally consistent with a black body at temperature 2.75 + or - 0.04 K at wavelengths from 0.1 to 12 cm, although some recent data (Kogut et al., 1988) seem to confirm the presence of distortion due to the Suniaev-Zel'dovich effect at wavelength 3.0 cm.

  8. 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

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

    SciTech Connect

    DeAbreu, Adam; Contreras, Dagoberto; Scott, Douglas E-mail: dagocont@phas.ubc.ca

    2015-12-01

    In a recent paper, Gurzadyan and 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.

  10. Fabrication of an Antenna-Coupled Bolometer for Cosmic Microwave Background Polarimetry

    NASA Astrophysics Data System (ADS)

    Denis, K. L.; Cao, N. T.; Chuss, D. T.; Eimer, J.; Hinderks, J. R.; Hsieh, W.-T.; Moseley, S. H.; Stevenson, T. R.; Talley, D. J.; U.-yen, K.; Wollack, E. J.

    2009-12-01

    We describe the development of a detector for precise measurements of the cosmic microwave background polarization. The detector employs a waveguide to couple light between a pair of Mo/Au superconducting transition edge sensors (TES) and a feedhorn. Incorporation of an on-chip ortho-mode transducer (OMT) results in high isolation. The OMT is micromachined and bonded to the microstrip and TES circuits in a low temperature wafer bonding process. The wafer bonding process incorporates a buried superconducting niobium layer with a single crystal silicon layer which serves as the leg isolated TES membrane and as the microstrip dielectric. We describe the micromachining and wafer bonding process and report measurement results of the microwave circuitry operating in the 29-45 GHz band along with Johnson noise measurements of the TES membrane structures and development of Mo/Au TES operating under 100 mK.

  11. 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.; hide

    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.

  12. A measurement of the cosmic microwave background temperature at 7.5 GHz

    NASA Technical Reports Server (NTRS)

    Levin, S.; Bensadoun, M.; Bersanelli, M.; De Amici, G.; Kogut, A.; Limon, M.; Smoot, G.

    1992-01-01

    The temperature of the cosmic microwave background (CMB) radiation at a frequency of 7.5 GHz (4 cm wavelength) is measured, obtaining a brightness temperature of T(CMB) = 2.70 +/- 0.08 K (68 percent confidence level). The measurement was made from a site near the geographical South Pole during the austral spring of 1989 and was part of an international collaboration to measure the CMB spectrum at low frequencies with a variety of radiometers from several different sites. This recent result is in agreement with the 1988 measurement at the same frequency, which was made from a different site with significantly different systematic errors. The combined result of the 1988 and 1989 measurements is 2.64 +/- 0.06 K.

  13. Measurements of the cosmic microwave background temperature at 1.47 GHz

    NASA Technical Reports Server (NTRS)

    Bensadoun, M.; Bersanelli, M.; De Amici, G.; Kogut, A.; Levin, S. M.; Limon, M.; Smoot, G. F.; Witebsky, C.

    1993-01-01

    We have used a radio-frequency-gain total-power radiometer to measure the intensity of the cosmic microwave background (CMB) at a frequency of 1.47 GHz (20.4 cm wavelength) from White Mountain, California in 1988 September and from the South Pole in 1989 December. The CMB thermodynamic temperature, T(CMB), is 2.27 +/- 0.25 K (68 percent confidence limit) measured from White Mountain and 2.26 +/- 0.20 K from the South Pole site. The combined result is 2.26 +/- 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 extrapolated from our zenith scan measurements at higher frequencies. These results are consistent with our previous measurement at 1.41 GHz and about 2.5 sigma from the 2.74 +/- 0.01 K global average CMB temperature.

  14. Effect of the early reionization on the cosmic microwave background and cosmological parameter estimates

    NASA Astrophysics Data System (ADS)

    Huang, Qing-Guo; Wang, Ke

    2017-07-01

    The early reionization (ERE) is supposed to be a physical process which happens after recombination, but before the instantaneous reionization caused by the first generation of stars. We investigate the effect of the ERE on the temperature and polarization power spectra of cosmic microwave background (CMB), and adopt principal components analysis (PCA) to model-independently reconstruct the ionization history during the ERE. In addition, we also discuss how the ERE affects the cosmological parameter estimates, and find that the ERE does not impose any significant influences on the tensor-to-scalar ratio r and the neutrino mass at the sensitivities of current experiments. The better CMB polarization data can be used to give a tighter constraint on the ERE and might be important for more precisely constraining cosmological parameters in the future.

  15. Detection of the power spectrum of cosmic microwave background lensing by the Atacama Cosmology Telescope.

    PubMed

    Das, Sudeep; Sherwin, Blake D; Aguirre, Paula; Appel, John W; Bond, J Richard; Carvalho, C Sofia; Devlin, Mark J; Dunkley, Joanna; Dünner, Rolando; Essinger-Hileman, Thomas; Fowler, Joseph W; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hincks, Adam D; Hlozek, Renée; Huffenberger, Kevin M; Hughes, John P; Irwin, Kent D; Klein, Jeff; Kosowsky, Arthur; Lupton, Robert H; Marriage, Tobias A; Marsden, Danica; Menanteau, Felipe; Moodley, Kavilan; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Parker, Lucas; Reese, Erik D; Schmitt, Benjamin L; Sehgal, Neelima; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Visnjic, Katerina; Wollack, Ed

    2011-07-08

    We report the first detection of the gravitational lensing of the cosmic microwave background through a measurement of the four-point correlation function in the temperature maps made by the Atacama Cosmology Telescope. We verify our detection by calculating the levels of potential contaminants and performing a number of null tests. The resulting convergence power spectrum at 2° angular scales measures the amplitude of matter density fluctuations on comoving length scales of around 100 Mpc at redshifts around 0.5 to 3. The measured amplitude of the signal agrees with Lambda cold dark matter cosmology predictions. Since the amplitude of the convergence power spectrum scales as the square of the amplitude of the density fluctuations, the 4σ detection of the lensing signal measures the amplitude of density fluctuations to 12%.

  16. 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.

  17. Measurement of the cosmic background radiation temperature at 3. 3 mm wavelength

    SciTech Connect

    Witebsky, C.

    1985-05-01

    Measurements of the cosmic background radiation (CBR) at 3.3 mm wavelength (90 GHz) have yielded a brightness temperature of 2.57 K with a 1sigma uncertainty of +-0.12 K. The observations were made from the Barcroft Laboratory of the White Mountain Research Station, at an altitude of 3800 m, initially on 5 and 6 July 1982 and again on 4,5, and 6 September 1983, as part of a program to measure the spectrum of the CBR at five wavelengths from 12.0 cm to 3.3 mm (Smoot, et al. 1985; Smoot, De Amici, Levin, and Witebsky 1985). The weighted mean of the temperature measurements at all five wavelengths is 2.72 +- 0.04 K. 97 refs., 13 figs., 14 tabs.

  18. A degree-scale measurement of anisotropy of the cosmic background radiation

    NASA Technical Reports Server (NTRS)

    Gaier, Todd; Schuster, Jeffrey; Gundersen, Joshua; Koch, Timothy; Seiffert, Michael; Meinhold, Peter; Lubin, Philip

    1992-01-01

    We report on the preliminary result of a search for anisotropy in the cosmic background radiation (CBR) with a beam size of about 1.5 deg FWHM over a wavelength range of 8-12 mm. The system operated successfully for 500 hr at the South Pole during the 1990-1991 austral summer. The data from one region, representing 25 hr after editing, are presented here. A strong signal is present in the lower frequency channels with a spectrum unlike CBR fluctuations, and is probably due to foreground emission. The highest frequency channel has the smallest contribution from this signal and has been used to set a 95-percent confidence level upper limit of not greater than 1.4 x 10 exp -5 for fluctuations with a Gaussian autocorrelation function at a coherence angle of 1.2 deg. This is significantly more sensitive than previous experiments at this angle scale.

  19. 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.

  20. Ribbons on the Cosmic Background Radiation Sky: A Powerful Test of a Baryon Symmetric Universe

    SciTech Connect

    Kinney, W.H.; Kolb, E.W.; Turner, M.S.; Turner, M.S.

    1997-10-01

    If the Universe consists of domains of matter and antimatter, annihilations at domain interfaces leave a distinctive imprint on the cosmic background radiation (CBR) sky. The signature is anisotropies in the form of long, thin ribbons of width {theta}{sub W}{approximately}0.1{sup {circ}} , separated by angle {theta}{sub L}{approx_equal}1{sup {circ}}(L/100h{sup {minus}1} Mpc) (L is the characteristic domain size) and with distortion parameter y{approx}10{sup {minus}6} . Such a pattern could potentially be detected by the high-resolution CBR anisotropy experiments planned for the next decade, and such experiments may finally settle the question of whether or not our Hubble volume is baryon symmetric. {copyright} {ital 1997} {ital The American Physical Society}

  1. Rocket measurement of the cosmic-background-radiation mm-wave spectrum

    SciTech Connect

    Gush, H.P.; Halpern, M.; Wishnow, E.H. )

    1990-07-30

    We report here the most precise constraint to date on the spectrum of the cosmic background radiation (CBR), obtained from measurements made with a liquid-helium-cooled spectrometer carried above the atmosphere on a rocket. The spectrum is very well fitted by a Planck function of temperature {ital T}=2.736 K. The scatter of the equivalent temperature in the band 3--16 cm{sup {minus}1} is {plus minus}10 mK, about 1/3% of the mean whereas the estimated overall accuracy of the mean temperature is {plus minus}17 mK. These results are inconsistent with a previously reported excess IR intensity in the CBR but are in good agreement with COBE results.

  2. Cosmic background radiation must appear smooth in an optically thick universe

    SciTech Connect

    Marks, D.W. )

    1990-01-01

    The recent discovery by Schneider, Schmidt, and Gunn (Astronomical Journal, 98(6), December 1989, 1951-58) of a quasar with a redshift factor z of 4.73 raises anew the question of how the universe could be so structured at that epoch despite being so smooth at the epoch of the cosmic background radiation (CBR). The smoothness of the CBR may, however, be illusory. In 1984, the author proved from relativistically invariant radiative transfer theory that, in an optically thick gas, the radiation should show only monopole, dipole, and quadrupole components with all higher-order multipole moments vanishing. Since Schneider Schmidt, and Gunn also measured an increase in intergalactic opacity for z > 4, the appearance of any inhomogeneities in the CBR may be washed out by opacity effects. Thus the smoothness of the CBR may be only a weak constraint on theories of galaxy formation.

  3. A precise measurement of the cosmic background radiation at 1. 32 millimeters

    SciTech Connect

    Palazzi, E.; Mandolesi, N.; Crane, P.; Kutner, M.L.; Blades, J.C. European Southern Observatory, Garching Rennselaer Polytechnic Institute, Troy, NY Space Telescope Science Institute, Baltimore, MD )

    1990-07-01

    A precise value of the cosmic background radiation temperature at 1.32 mm has been determined from the interstellar absorption lines of the CN molecule toward HD 154368. Equivalent widths for CN and (C-13)N in the main cloud are reported. A very weak secondary cloud has been discovered. Millimeter observations at 2.64 mm revealed weak CN emission from the main cloud with T-asterisk(R) = 19.0 + or - 5.1 mK. Thus there is some local excitation of CN. Correcting for this yields T(CBR) = 2.832 + or - 0.072 K at 1.32 mm which when combined with the result of Meyer et al. (1989) gives the T(CBR) = 2.831 + or - 0.056 K at 1.32 mm. At 2.64 mm, T(CBR) = 2.834 + or - 0.085 K is found. 25 refs.

  4. Cosmic background radiation anisotropies in universes dominated by nonbaryonic dark matter

    NASA Technical Reports Server (NTRS)

    Bond, J. R.; Efstathiou, G.

    1984-01-01

    Detailed calculations of the temperature fluctuations in the cosmic background radiation for universes dominated by massive collisionless relics of the big bang are presented. An initially adiabatic constant curvature perturbation spectrum is assumed. In models with cold dark matter, the simplest hypothesis - that galaxies follow the mass distribution leads to small-scale anisotropies which exceed current observational limits if omega is less than 0.2 h to the -4/3. Since low values of omega are indicated by dynamical studies of galaxy clustering, cold particle models in which light traces mass are probably incorrect. Reheating of the pregalactic medium is unlikely to modify this conclusion. In cold particle or neutrino-dominated universes with omega = 1, presented predictions for small-scale and quadrupole anisotropies are below current limits. In all cases, the small-scale fluctuations are predicted to be about 10 percent linearly polarized.

  5. A new line-of-sight approach to the non-linear Cosmic Microwave Background

    SciTech Connect

    Fidler, Christian; Koyama, Kazuya; Pettinari, Guido W. E-mail: kazuya.koyama@port.ac.uk

    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.

  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. 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.

  8. Low-frequency measurements of the CMB (cosmic microwave background) spectrum

    SciTech Connect

    Kogut, A.; Bensadoun, M.; De Amici, G.; Levin, S.; Limon, M.; Smoot, G. ); Sironi, G. . Dipt. di Fisica); Bersanelli, M.; Bonelli, G. )

    1989-10-01

    As part of an extended program to characterize the spectrum of the cosmic microwave background (CMB) at low frequencies, we have performed multiple measurements from a high-altitude site in California. On average, these measurements suggest a CMB temperature slightly lower than measurements at higher frequencies. Atmospheric conditions and the encroachment of civilization are now significant limitations from our present observing site. In November 1989, we will make new measurements from the South Pole Amnudsen-Scott Station at frequencies 0.82 1.5, 2.5, 3.8, 7.5, and 90 GHz. We discuss recent measurements and indicate improvements from a polar observing site. 11 refs., 2 figs.

  9. Cosmic Microwave Background large-scale directional anomalies as seen by Planck and WMAP

    NASA Astrophysics Data System (ADS)

    Polastri, L.

    2017-05-01

    It has been found that large-scale anisotropies in the Cosmic Microwave Background are anomalous with respect to the predictions of the standard model of cosmology. We focused on the low multipole alignments, assuming the ΛCDM model and we confirmed that the quadrupole/octupole and the dipole/quadrupole/octupole alignments are anomalous with a significance up to 99.9%, for both WMAP and Planck data. Trying to explain the origin of this kind of anomalies we tested the dipolar model. This alternative phenomenological model explains the CMB hemispherical power asymmetry found in the WMAP and Planck data, so is possible that it can solve also other CMB directional anomalies. We show that the alignments are anomalous in the dipolar model too, roughly at the same level as in ΛCDM. We conclude that the dipolar model does not provide a better fit to the data than the ΛCDM.

  10. Searching for CPT violation with cosmic microwave background data from WMAP and BOOMERANG.

    PubMed

    Feng, Bo; Li, Mingzhe; Xia, Jun-Qing; Chen, Xuelei; Zhang, Xinmin

    2006-06-09

    We search for signatures of Lorentz and violations in the cosmic microwave background (CMB) temperature and polarization anisotropies by using the Wilkinson Microwave Anisotropy Probe (WMAP) and the 2003 flight of BOOMERANG (B03) data. We note that if the Lorentz and symmetries are broken by a Chern-Simons term in the effective Lagrangian, which couples the dual electromagnetic field strength tensor to an external four-vector, the polarization vectors of propagating CMB photons will get rotated. Using the WMAP data alone, one could put an interesting constraint on the size of such a term. Combined with the B03 data, we found that a nonzero rotation angle of the photons is mildly favored: [Formula: See Text].

  11. SPOrt: an experiment aimed at measuring the large scale cosmic microwave background polarization

    NASA Astrophysics Data System (ADS)

    Carretti, Ettore; Cortiglioni, Stefano; Bernardi, Gianni; Cecchini, Stefano; Macculi, Claudio; Sbarra, Carla; Monari, Jader; Orfei, Alessandro; Poloni, Marco; Poppi, Sergio; Boella, Giuliano; Bonometto, Silvio; Gervasi, Massimo; Sironi, Giorgio; Zannoni, Mario; Tucci, Marco; Baralis, Massino; Peverini, Oscar A.; Tascone, Riccardo; Virone, Giuseppe; Fabbri, Roberto; Nicastro, Luciano; Ng, Kin-Wang; Razin, V. A.; Vinyajkin, Evgenij N.; Sazhin, Mikhail V.; Strukov, Igor A.

    2003-02-01

    SPOrt (Sky Polarization Observatory) is a space experiment to be flown on the International Space Station during Early Utilization Phase aimed at measuring the microwave polarized emission with FWHM = 7 deg, in the frequency range 22-90 GHz. The Galactic polarized emission can be observed at the lower frequencies and the polarization of Cosmic Microwave Background (CMB) at 90 GHz, where contaminants are expected to be less important. The extremely low level of the CMB Polarization signal calls for intrinsically stable radiometers. The SPOrt instrument is expressly devoted to CMB polarization measurements and the whole design has been optimized for minimizing instrumental polarization effects. In this contribution we present the receiver architecture based on correlation techniques, the analysis showing its intrinsic stability and the custom hardware development carried out to detect such a low signal.

  12. 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.

  13. Parity violation in the Cosmic Microwave Background from a pseudoscalar inflaton

    SciTech Connect

    Sorbo, Lorenzo

    2011-06-01

    If the inflaton φ is a pseudoscalar, then it naturally interacts with gauge fields through the coupling ∝φ F{sub μν} F-tilde {sup μν}. Through this coupling, the rolling inflaton produces quanta of the gauge field, that in their turn source the tensor components of the metric perturbations. Due to the parity-violating nature of the system, the right- and the left-handed tensor modes have different amplitudes. Such an asymmetry manifests itself in the form of non-vanishing TB and EB correlation functions in the Cosmic Microwave Background (CMB). We compute the amplitude of the parity-violating tensor modes and we discuss two scenarios, consistent with the current data, where parity-violating CMB correlation functions will be detectable in future experiments.

  14. 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.

  15. 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.

  16. Characterization of a high-temperature superconducting bearing for use in a cosmic microwave background polarimeter

    NASA Astrophysics Data System (ADS)

    Hull, John R.; Hanany, Shaul; Matsumura, Tomotake; Johnson, Bradley; Jones, Terry

    2005-02-01

    We have previously presented a design for a cosmic microwave background (CMB) polarimeter in which a cryogenically cooled half-wave plate rotates by means of a high-temperature superconducting (HTS) bearing. Here, a prototype bearing, consisting of a commercially available ring-shaped permanent magnet and an array of YBCO bulk HTS material, has been constructed. We measured its coefficient of friction and vibrational property as a function of several parameters, including temperature between 15 and 83 K, rotation frequency between 0.3 and 3.5 Hz, levitation distance between 6 and 10 mm and ambient pressure of {\\sim }10^{- 7} Torr. We concluded that the low rotational drag of the HTS bearing would allow rotations for long periods with minimal input power and negligible wear and tear, thus making this technology suitable for a future satellite mission.

  17. Optimal cosmic microwave background map-making in the presence of cross-correlated noise

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    Aims: We present an extension of the ROMA map-making algorithm for the generation of optimal cosmic microwave background polarization maps. The new code allows for a possible cross-correlated noise component among the detectors of a CMB experiment. A promising application is the forthcoming LSPE balloon-borne experiment, which is devoted to the accurate observation of CMB polarization at large angular scales. Methods: We generalized the noise covariance matrix in time domain to account for all the off-diagonal terms due to the detector cross-talk. Hence, we performed preliminary forecasts of the LSPE-SWIPE instrument. Results: We found that considering the noise cross-correlation among the detectors results in a more realistic estimate of the angular power spectra. In particular, the extended ROMA algorithm has provided a considerable reduction of the spectra error bars. We expect that this improvement could be crucial in constraining the B-mode polarization at the largest scales.

  18. 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.

  19. Q/U Imaging Experiment (QUIET): a ground-based probe of cosmic microwave background polarization

    NASA Astrophysics Data System (ADS)

    Buder, Immanuel

    2010-07-01

    QUIET is an experimental program to measure the polarization of the Cosmic Microwave Background (CMB) radiation from the ground. Previous CMB polarization data have been used to constrain the cosmological parameters that model the history of our universe. The exciting target for current and future experiments is detecting and measuring the faint polarization signals caused by gravity waves from the inflationary epoch which occurred < 10-30 s after the Big Bang. QUIET has finished an observing season at 44 GHz (Q-Band); observing at 95 GHz (W-Band) is ongoing. The instrument incorporates several technologies and approaches novel to CMB experiments. We describe the observing strategy, optics design, detector technology, and data acquisition. These systems combine to produce a polarization sensitivity of 64 (57) μK for a 1 s exposure of the Phase I Q (W) Band array. We describe the QUIET Phase I instrument and explain how systematic errors are reduced and quantified.

  20. New Measurements of the Cosmic Background Radiation Temperature at3.3 mm Wavelength

    SciTech Connect

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

    1986-02-01

    We have measured the temperature of the cosmic background radiation (CBR) at 3.3 mm wavelength in 1982, 1983, and 1984 as part of a larger project to determine the CBR temperature at five wavelengths from 12 cm to 3.3 mm (Smoot et al. 1985). The 3.3-mm measurements yield a brightness temperature of 2.57 K with a 1{sigma} uncertainty of 20.12 K. This paper describes the instrument, the measurement techniques, and the data-analysis procedures used. Our result is in good agreement with recent measurements at comparable wavelengths by Meyer and Jura (1985) and by Peterson, Richards, and Timusk (1985), but it disagrees with the temperatures reported by Woody and Richards (1981).