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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

    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.

  3. 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.

  4. 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).

  5. Cosmic Background Explorer (COBE): Emergency support

    NASA Technical Reports Server (NTRS)

    Stanford, R.; Mattson, R.

    1991-01-01

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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

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

    NASA Technical Reports Server (NTRS)

    Placanica, Samuel J.; Flatley, Thomas W.

    1986-01-01

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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. The Primordial Inflation Explorer (PIXIE): A Nulling Polarimeter for Cosmic Microwave Background Observations

    NASA Technical Reports Server (NTRS)

    Kogut, Alan J.; Fixsen, D. J.; Chuss, D. T.; Dotson, J.; Dwek, E.; Halpern, M.; Hinshaw, G. F.; Meyer, S. M.; Moseley, S. H.; Seiffert, M. D.; Spergel, D. N.; Wollack, E. J.

    2011-01-01

    The Primordial Inflation Explorer (PIXIE) is a concept for an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. The instrument consists of a polarizing Michelson interferometer configured as a nulling polarimeter to measure the difference spectrum between orthogonal linear polarizations from two co-aligned beams. Either input can view the sky or a temperature-controlled absolute reference blackbody calibrator. Rhe proposed instrument can map the absolute intensity and linear polarization (Stokes I, Q, and U parameters) over the full sky in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). Multi-moded optics provide background-limited sensitivity using only 4 detectors, while the highly symmetric design and multiple signal modulations provide robust rejection of potential systematic errors. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r < 10..3 at 5 standard deviations. The rich PIXIE data set can also constrain physical processes ranging from Big Bang cosmology to the nature of the first stars to physical conditions within the interstellar medium of the Galaxy.

  18. Cryogenic Optical Assembly (COA) cooldown analysis for the Cosmic Background Explorer (COBE)

    NASA Technical Reports Server (NTRS)

    Coladonato, Robert J.; Irish, Sandra M.; Mosier, Carol L.

    1990-01-01

    The Cosmic Background Explorer (COBE) spacecraft, developed by Goddard Space Flight Center (GSFC), was successfully launched on November 18, 1989 aboard a Delta expendable launch vehicle. Two of the three instruments for this mission were mounted inside a liquid helium (LHe) dewar which operates at a temperature of 2 K. These two instruments are the Diffuse Infrared Background Experiment (DIRBE) and the Far Infrared Absolute Spectrophotometer (FIRAS). They are mounted to a common Instrument Interface Structure (IIS) and the entire assembly is called the Cryogenic Optical Assembly (COA). As part of the structural verification requirement, it was necessary to show that the entire COA exhibited adequate strength and would be capable of withstanding the launch environment. This requirement presented an unique challenge for COBE because the COA is built and assembled at room temperature (300 K), cooled to 2 K, and then subjected to launch loads. However, strength testing of the entire COA at 2 K could not be done because of facility limitations. Therefore, it was decided to perform the strength verification of the COA by analysis.

  19. Test facility requirements for the thermal vacuum thermal balance test of the Cosmic Background Explorer Observatory

    NASA Technical Reports Server (NTRS)

    Milam, Laura J.

    1991-01-01

    The Cosmic Background Explorer Observatory (COBE) underwant a thermal vacuum thermal balance test in the Space Environment Simulator (SES). This was the largest and most complex test ever conducted at this facility. The 4 x 4 m (13 x 13 ft) spacecraft weighed approx. 2223 kg (4900 lbs) for the test. The test set up included simulator panels for the inboard solar array panels, simulator panels for the flight cowlings, Sun and Earth Sensor stimuli, Thermal Radio Frequency Shield heater stimuli and a cryopanel for thermal control in the Attitude Control System Shunt Dissipator area. The fixturing also included a unique 4.3 m (14 ft) diameter Gaseous Helium Cryopanel which provided a 20 K environment for the calibration of one of the spacecraft's instruments, the Differential Microwave Radiometer. This cryogenic panel caused extra contamination concerns and a special method was developed and written into the test procedure to prevent the high buildup of condensibles on the panel which could have led to backstreaming of the thermal vacuum chamber. The test was completed with a high quality simulated space environment provided to the spacecraft. The test requirements, test set up, and special fixturing are described.

  20. Fault tolerant capabilities of the Cosmic Background Explorer attitude control system

    NASA Technical Reports Server (NTRS)

    Placanica, Samuel J.

    1992-01-01

    The Cosmic Background Explorer (COBE), which was launched November 18, 1989 from Vandenberg Air Force Base aboard a Delta rocket, has been classified by the scientific community as a major success with regards to the field of cosmology theory. Despite a number of anomalies which have occurred during the mission, the attitude control system (ACS) has performed remarkably well. This is due in large part to the fault tolerant capabilities that were designed into the ACS. A unique triaxial control system orientated in the spacecraft's transverse plane provides the ACS the ability to safely survive various sensor and actuator failures. Features that help to achieve this fail-operational system include component cross-strapping and autonomous control electronics switching. This design philosophy was of utmost importance because of the constraint placed upon the ACS to keep the spinning observatory and its cryogen-cooled science instruments pointing away from the sun. Even though the liquid helium was depleted within the expected twelve months from launch, it is still very much desirable to avoid any thermal disturbances upon the remaining functional instruments.

  1. Measured ground performance and predicted orbital performance of the superfluid helium dewar for the Cosmic Background Explorer

    NASA Technical Reports Server (NTRS)

    Hopkins, Richard A.; Ryschkewitsch, M. G.

    1986-01-01

    A critical component of the Cosmic Background Explorer observatory, which is to be lifted to orbit in 1988, is the 650-l superfluid He dewar housing a far-IR absolute spectrophotometer and a diffuse IR background experiment. Attention is presently given to the results of a four-month-long test program encompassing dewar filling verification, vibration characteristics, thermal performance over orbital lifetime, and aperture cover ejection behavior. No significant flaws have been noted; the orbital cryogen lifetime is projected to be 14 months.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. The cosmic microwave background radiation

    NASA Technical Reports Server (NTRS)

    Silk, Joseph

    1992-01-01

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

  8. 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

  9. [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.

  10. [Cosmic Microwave Background (CMB) Anisotropies

    NASA Astrophysics Data System (ADS)

    Silk, Joseph

    1998-01-01

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

  11. Polarization of Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  12. Characterizing the Cosmic Infrared Background Fluctuations

    NASA Astrophysics Data System (ADS)

    Li, Yanxia

    2015-08-01

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

  13. 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).

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

    NASA Astrophysics Data System (ADS)

    Wu, Jiun-Huei Proty

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

  15. 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.

  16. Gravitational-wave stochastic background from cosmic strings.

    PubMed

    Siemens, Xavier; Mandic, Vuk; Creighton, Jolien

    2007-03-16

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

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

    PubMed

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

    2007-12-01

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

  18. 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.

  19. Cosmic-ray backgrounds in infrared bolometers

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  20. Spectral distortions of the cosmic microwave background

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  1. 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.

  2. 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.

  3. Search for the Cosmic Neutrino Background

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  4. Cosmic Microwave Background spectral distortions from cosmic string loops

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    PubMed

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

    2008-01-18

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

  6. 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.

  7. Precision measurements of the cosmic microwave background

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  8. Cosmic string collision in cosmological backgrounds

    SciTech Connect

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

    2010-06-15

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

  9. Cosmic microwave background acoustic peak locations

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  10. Neutrino refraction by the cosmic neutrino background

    NASA Astrophysics Data System (ADS)

    Díaz, J. S.; Klinkhamer, F. R.

    2016-03-01

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

  11. Characterizing the Cosmic Infrared Background Fluctuations

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  12. 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.

  13. Polarization observations with the Cosmic Background Imager.

    PubMed

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

    2004-10-29

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

  14. 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).

  15. 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.

  16. Signatures of a hidden cosmic microwave background.

    PubMed

    Jaeckel, Joerg; Redondo, Javier; Ringwald, Andreas

    2008-09-26

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

  17. 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.

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

    SciTech Connect

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

    2011-03-01

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

  19. 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.

  20. 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.

  1. Introductory Remarks to Cosmic Background Parallel Sessions.

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  2. Cosmic axion background propagation in galaxies

    NASA Astrophysics Data System (ADS)

    Day, Francesca V.

    2016-02-01

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

  3. 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.

  4. 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.

  5. Physics of the cosmic microwave background anisotropy

    NASA Astrophysics Data System (ADS)

    Bucher, Martin

    2015-01-01

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

  6. 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.

  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. The POLARBEAR Cosmic Microwave Background Polarization Experiment

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  9. 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.

  10. 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.

  11. Ultraviolet background radiation from cosmic structure formation

    NASA Astrophysics Data System (ADS)

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

    2004-03-01

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

  12. Information gains from cosmic microwave background experiments

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  13. Spatial Statistics of Cosmic Microwave Background Maps

    NASA Astrophysics Data System (ADS)

    Szapudi, I.

    2007-11-01

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

  14. 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.

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

    SciTech Connect

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

    2010-04-15

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

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

    NASA Astrophysics Data System (ADS)

    Casimiro, E.; Anjos, J. C.

    2008-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Signore, Monique; Puy, Denis

    2009-01-01

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

  18. 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.

  19. 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.

  20. 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.

  1. Cosmic Infrared Background and Early Galaxy Evolution

    NASA Technical Reports Server (NTRS)

    Kashlinsky, Alexander

    2005-01-01

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

  2. 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.

  3. Hot Universe Background Explorer (HUBE)

    NASA Astrophysics Data System (ADS)

    Henry, R. C.; Murthy, J.; Ford, H.; Peacock, K.; Burrows, D. N.; Smith, B. W.; Bloch, J. J.

    1998-05-01

    The study of diffuse backgrounds has played an important role in the recent history of astronomy. From the microwave discovery of the 2.7 K background to the soft X-ray detection of coronal gas to the diffuse H2 emission from warm interstellar gas in our galaxy to the infrared mapping of wisps of dust at high galactic latitudes, diffuse background astronomy has provided fundamental insights into the nature of the universe. As the various regions of the electromagnetic spectrum have been explored, their diffuse backgrounds have been found to arise from the widest possible range of sources: from the local interstellar medium to the farthest reaches of the observable universe; from the wrinkled echo of the Big Bang to the million degree plasma between the stars. Most astronomers are ``point-source" astronomers, and the history of astronomy space missions is that few have been dedicated to the elucidation of the nature of the truly diffuse radiation. And yet a large fraction of the total electromagnetic energy in the universe occurs in the form of diffuse radiation. In some spectral ranges, we do not yet know the fraction of radiation that is diffuse; we are dealing with genuinely unexplored frontiers. We will describe the extraordinary science that can be obtained through a MIDEX mission that is dedicated to the exploration of the diffuse emission in the far ultraviolet and soft X-ray regions of the spectrum, where the diffuse radiation is dominated by emission from the hottest components of the interstellar medium and, perhaps, from the intergalactic medium. HUBE currently enjoys the status of being NASA's MIDEX Alternate Astrophysics Mission. We are re-proposing HUBE in the current MIDEX competition with a much broader scientific set of goals, aiming at a definitive spectroscopic survey of the diffuse background over a greatly-expanded spectral range. Our HUBE proposal effort is being supported by Ball Aerospace Corporation.

  4. 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.

  5. Origin of the high energy cosmic neutrino background.

    PubMed

    Dado, Shlomo; Dar, Arnon

    2014-11-01

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

  6. 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. .

  7. Search for Cosmic Strings in Cosmic Microwave BackgroundAnisotropies

    SciTech Connect

    Jeong, E.; Smoot, GF

    2004-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Miniati, Francesco

    2002-11-01

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

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

    PubMed

    Rocher, Jonathan; Sakellariadou, Mairi

    2005-01-14

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

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

    NASA Astrophysics Data System (ADS)

    Lagache, Guilaine

    2015-08-01

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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

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

    SciTech Connect

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

    2013-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  17. Radio brightness distribution within cosmic background fluctuations

    NASA Astrophysics Data System (ADS)

    Sazhin, M. V.

    1985-08-01

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

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1980-04-01

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

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Spectral distortions and anisotropies of the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    De Zotti, Gianfranco; Negrello, Mattia

    2015-12-01

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

  6. Real-time active cosmic neutron background reduction methods

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  7. 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

  8. Distortions of the cosmic microwave background spectrum by dust

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

  9. 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

  10. 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.

  11. GIANT RINGS IN THE COSMIC MICROWAVE BACKGROUND SKY

    SciTech Connect

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

    2010-11-20

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

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

    PubMed

    Seshadri, T R; Subramanian, K

    2001-09-01

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

  13. How to fool cosmic microwave background parameter estimation

    SciTech Connect

    Kinney, William H.

    2001-02-15

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

  14. 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.

  15. 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.

  16. 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.

  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. 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.

  19. 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.

  20. 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.

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

    SciTech Connect

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

    2014-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  4. Consistent cosmic microwave background spectra from quantum depletion

    NASA Astrophysics Data System (ADS)

    Casadio, Roberto; Kühnel, Florian; Orlandi, Alessio

    2015-09-01

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

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

    PubMed

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

    2014-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  7. 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)

  8. Constraining invisible neutrino decays with the cosmic microwave background

    SciTech Connect

    Hannestad, Steen; Raffelt, Georg G.

    2005-11-15

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

  9. Cosmic microwave background anisotropies generated by domain wall networks

    NASA Astrophysics Data System (ADS)

    Sousa, L.; Avelino, P. P.

    2015-10-01

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

  10. GALAXY COUNTS ON THE COSMIC MICROWAVE BACKGROUND COLD SPOT

    SciTech Connect

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

    2010-05-01

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

  11. The cosmic ray antiproton background for AMS-02

    SciTech Connect

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

    2014-09-01

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

  12. 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.

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

    NASA Astrophysics Data System (ADS)

    Vallinotto, Alberto

    2012-11-01

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

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

    SciTech Connect

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

    2011-06-10

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

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

    NASA Astrophysics Data System (ADS)

    Sanchez, N.; Signore, M.

    1989-03-01

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

  16. 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

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

    PubMed

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

    2011-08-01

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

  18. Dark energy and the cosmic microwave background radiation.

    PubMed

    Dodelson, S; Knox, L

    2000-04-17

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

  19. Cosmic microwave background radiation anisotropies in brane worlds.

    PubMed

    Koyama, Kazuya

    2003-11-28

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

  20. Fisher matrix optimization of cosmic microwave background interferometers

    NASA Astrophysics Data System (ADS)

    Liu, Haonan; Bunn, Emory F.

    2016-01-01

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

  1. 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.

  2. 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.

  3. Introduction to temperature anisotropies of Cosmic Microwave Background radiation

    NASA Astrophysics Data System (ADS)

    Sugiyama, Naoshi

    2014-06-01

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

  4. 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.

  5. 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.

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

    SciTech Connect

    Kasuya, S.; Kawasaki, M.

    2004-11-15

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

  7. Fisher Matrix Optimization of Cosmic Microwave Background Interferometry

    NASA Astrophysics Data System (ADS)

    Liu, Haonan; Bunn, Emory F.

    2016-01-01

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

  8. 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

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

    NASA Astrophysics Data System (ADS)

    Simard, Gabrielle; Hanson, Duncan; Holder, Gil

    2015-07-01

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

  10. Cosmic microwave background bispectrum on small angular scales

    SciTech Connect

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

    2008-09-15

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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Reichardt, Christian L.

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

  16. 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

  17. 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).

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

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

  20. 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.

  1. Searching for stringy topologies in the cosmic microwave background

    SciTech Connect

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

    2012-11-01

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

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

    SciTech Connect

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

    2013-09-01

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

  3. 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).

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

    PubMed

    Niarchou, Anastasia; Jaffe, Andrew

    2007-08-24

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

  5. Dipole modulation of cosmic microwave background temperature and polarization

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  6. 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.

  7. 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.

  8. 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.

  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. 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.

  11. Radiometer system to map the cosmic background radiation.

    PubMed

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

    1978-04-01

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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Herschel/PEP Dissects the Cosmic Infrared Background

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  17. 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.

  18. 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.

  19. Distinguishing between inflationary models from cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Tsujikawa, Shinji

    2014-06-01

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

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

    NASA Technical Reports Server (NTRS)

    Persi, Fred M.

    1995-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Merkel, Philipp M.; Schäfer, Björn Malte

    2015-10-01

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

  2. A circular polarimeter for the Cosmic Microwave Background

    SciTech Connect

    Giovannini, Massimo

    2010-08-01

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

  3. Constraining light gravitino mass from cosmic microwave background

    SciTech Connect

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

    2009-08-01

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

  4. 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.

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

    PubMed

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

    2006-07-14

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

  6. 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.

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

    SciTech Connect

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

    2001-01-15

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

  8. 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.

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

    SciTech Connect

    Pontzen, Andrew; Peiris, Hiranya V.

    2010-05-15

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

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Crites, Abigail; SPT-POL Collaboration

    2013-01-01

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

  12. Spectral distortions in the cosmic microwave background polarization

    SciTech Connect

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

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

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

    SciTech Connect

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

    2008-10-15

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

  15. 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.

  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. Reconstructing patchy reionization from the cosmic microwave background

    SciTech Connect

    Dvorkin, Cora; Smith, Kendrick M.

    2009-02-15

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

  18. The information content of cosmic microwave background anisotropies

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

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

    PubMed

    Mukherjee, Suvodip; Souradeep, Tarun

    2016-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Wibig, Tadeusz; Wolfendale, Arnold W.

    2016-01-01

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

  1. 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.

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

    SciTech Connect

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

    2009-10-01

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

  3. 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.

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

    NASA Technical Reports Server (NTRS)

    Forman, William R.

    1996-01-01

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

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    Imara, Nia; Loeb, Abraham

    2016-07-01

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

  7. 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.

  8. 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").

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

    NASA Astrophysics Data System (ADS)

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

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

  10. SELF-CALIBRATION OF COSMIC MICROWAVE BACKGROUND POLARIZATION EXPERIMENTS

    SciTech Connect

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

    2013-01-10

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

  11. High Resolution Observations of the Cosmic Microwave Background Radiation

    NASA Astrophysics Data System (ADS)

    Holzapfel, W. L.

    2005-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-10-01

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

  13. 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.

  14. Cosmology from secondary anisotropies of the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Sherwin, Blake Daniel

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  16. 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.

  17. 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

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

    PubMed

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

    2015-12-31

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

  19. Degree Scale Anisotropy Measurements of the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Gundersen, Joshua Ott

    1995-01-01

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

  20. 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

  1. 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.

  2. 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.

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

    SciTech Connect

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

    2010-05-15

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

  4. 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

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

    NASA Technical Reports Server (NTRS)

    Kamionkowski, Marc; Spergel, David N.

    1994-01-01

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

  9. 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.

  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. 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

  12. Achromatic half-wave plate for submillimeter instruments in cosmic microwave background astronomy: experimental characterization.

    PubMed

    Pisano, Giampaolo; Savini, Giorgio; Ade, Peter A R; Haynes, Vic; Gear, Walter K

    2006-09-20

    An achromatic half-wave plate (HWP) to be used in millimeter cosmic microwave background (CMB) polarization experiments has been designed, manufactured, and tested. The design is based on the 5-plates Pancharatnam recipe and it works in the frequency range 85-185 GHz. A model has been used to predict the transmission, reflection, absorption, and phase shift as a function of frequency. The HWP has been tested by using coherent radiation from a back-wave oscillator to investigate its modulation efficiency and with incoherent radiation from a polarizing Fourier transform spectrometer (FTS) to explore its frequency behavior. The FTS measurements have been fitted with an optical performance model which is in excellent agreement with the data. A detailed analysis of the data also allows a precise determination of the HWP fast and slow axes in the frequency band of operation. A list of the HWP performance characteristics is reported including estimates of its cross polarization. PMID:16946775

  13. Systematic Effects in Polarizing Fourier Transform Spectrometers for Cosmic Microwave Background Observations

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    The detection of the primordial B-mode polarization signal of the cosmic microwave background (CMB) would provide evidence for inflation. Yet as has become increasingly clear, the detection of a such a faint signal requires an instrument with both wide frequency coverage to reject foregrounds and excellent control over instrumental systematic effects. Using a polarizing Fourier transform spectrometer (FTS) for CMB observations meets both of these requirements. In this work, we present an analysis of instrumental systematic effects in polarizing FTSs, using the Primordial Inflation Explorer (PIXIE) as a worked example. We analytically solve for the most important systematic effects inherent to the FTS—emissive optical components, misaligned optical components, sampling and phase errors, and spin synchronous effects—and demonstrate that residual systematic error terms after corrections will all be at the sub-nK level, well below the predicted 100 nK B-mode signal.

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

    NASA Astrophysics Data System (ADS)

    Inoue, Yoshiyuki; Tanaka, Yasuyuki T.

    2016-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1994-12-01

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

  16. Progress in understanding the diffuse UV cosmic background

    NASA Astrophysics Data System (ADS)

    Henry, Richard Conn

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

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

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

  18. Egyptian exploration: background, models, and future potential

    SciTech Connect

    Kanes, W.H.; Abdine, S.

    1983-03-01

    Egypt has proven to be an area with excelllnt exploration potential. Recent discoveries in the Western Desert tilted fault blocks are leading to a reevaluation of new play concepts based on an east-west Tethyan rift structure model. Facies favorable to hydrocarbon accumulation are associated with shallow-water marine depositional environments. Production has not been great on a per-well basis, but fields have consistently out-produced the original recoverable reserve estimates. The Gulf of Suez lies within the rift between North Africa and Arabia-Sinai. It remains a major producing area with production from sandstones which range in age from Carboniferous to Cretaceous. The Upper Cretaceous and Lower Tertiary carbonates are potentially attractive zones, as are the Miocene clastics and carbonates. Miocene marls and Upper Cretaceous shales are source rocks, and thermal maturation can be directly related to continental rifting with the oil window most attractive in the southern third of the Gulf of Suez. Structural style is strongly rift-influenced with tilted and locally eroded hosts prevalent. The central gulf has a general eastern dip, whereas the northern and southern areas have a regional westward dip. This has had a direct influence in isolating some major oil fields and has adversely affected reflection seismic surveys. Exploration has been difficult because of excessive Miocene and younger salt thicknesses. With increasingly refined technology, attractive targets now are being delineated in the hitherto unexplored lows between horsts within the gulf.

  19. 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.

  20. 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.

  1. 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.

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

    PubMed

    Conlon, Joseph P; Marsh, M C David

    2013-10-11

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

  3. 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.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

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

    SciTech Connect

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

    2009-02-15

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

  7. Detection of high energy cosmic rays with the resonant gravitational wave detectors NAUTILUS and EXPLORER

    NASA Astrophysics Data System (ADS)

    Astone, P.; Babusci, D.; Bassan, M.; Bonifazi, P.; Cavallari, G.; Coccia, E.; D'Antonio, S.; Fafone, V.; Giordano, G.; Ligi, C.; Marini, A.; Mazzitelli, G.; Minenkov, Y.; Modena, I.; Modestino, G.; Moleti, A.; Pallottino, G. V.; Pizzella, G.; Quintieri, L.; Rocchi, A.; Ronga, F.; Terenzi, R.; Visco, M.

    2008-11-01

    The cryogenic resonant gravitational wave detectors NAUTILUS and EXPLORER, made of an aluminum alloy bar, can detect cosmic ray showers. At temperatures above 1 K, when the material is in the normal-conducting state, the measured signals are in good agreement with the expected values based on the cosmic rays data and on the thermo-acoustic model. When NAUTILUS was operated at the temperature of 0.14 K, in superconductive state, large signals produced by cosmic ray interactions, more energetic than expected, were recorded. The NAUTILUS data in this case are in agreement with the measurements done by a dedicated experiment on a particle beam. The biggest recorded event was in EXPLORER and excited the first longitudinal mode to a vibrational energy of ˜670 K, corresponding to ˜360 TeV absorbed in the bar. Cosmic rays can be an important background in future acoustic detectors of improved sensitivity. At present, they represent a useful tool to verify the gravitational wave antenna performance.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

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

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

    PubMed

    Sigurdson, Kris; Cooray, Asantha

    2005-11-18

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