WorldWideScience

Sample records for cosmic background radiation

  1. Cosmic Tachyon Background Radiation

    CERN Document Server

    Tomaschitz, R

    1999-01-01

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

  2. Testing inflation with the cosmic background radiation

    CERN Document Server

    Bond, J R

    1994-01-01

    In inflation cosmologies, cosmic structure develops through the gravitational instability of the inevitable quantum noise in primordial scalar fields. I show how the acceleration of the universe defines the shape of the primordial spectrum of gravitational metric and scalar field fluctuations. I assess how we can determine the shape and overall amplitude over the five decades or so of spatial wavelengths we can probe, and use current data ... to show how far we are in this program. Broad-band power amplitudes are given for CMB anisotropy detections up to spring 1994 ... I show that COBE band-powers found with full Bayesian analysis of the 53,90,31 a+b GHz first year DMR (and FIRS) maps are in good agreement, and are essentially independent of spectral slope and degree of (sharp) signal-to-noise filtering. Further, after (smooth) optimal signal-to-noise filtering (\\ie Weiner-filtering), the different DMR maps reveal the same large scale features and correlation functions with little dependence upon slope. Howe...

  3. Cosmic Rays Induced Background Radiation on Board of Commercial Flights

    CERN Document Server

    Pinilla, S; Núñez, L A

    2015-01-01

    The aim of this work is to determine the total integrated flux of cosmic radiation which a commercial aircraft is exposed to along specific flight trajectories. To study the radiation background during a flight and its modulation by effects such as altitude, latitude, exposure time and transient magnetospheric events, we perform simulations based on Magnetocosmics and CORSIKA codes, the former designed to calculate the geomagnetic effects on cosmic rays propagation and the latter allows us to simulate the development of extended air showers in the atmosphere. In this first work, by considering the total flux of cosmic rays from 5 GeV to 1 PeV, we obtained the expected integrated flux of secondary particles on board of a commercial airplane during the Bogot\\'a-Buenos Aires trip by point-to-point numerical integration.

  4. THE MYSTERY OF THE COSMIC DIFFUSE ULTRAVIOLET BACKGROUND RADIATION

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Richard Conn [Henry A. Rowland Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (United States); Murthy, Jayant [Indian Institute of Astrophysics, Bengaluru (India); Overduin, James; Tyler, Joshua, E-mail: henry@jhu.edu, E-mail: jmurthy@yahoo.com, E-mail: joverduin@towson.edu, E-mail: 97tyler@cardinalmail.cua.edu [Department of Physics, Astronomy and Geosciences, Towson University, Towson, MD 21252 (United States)

    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. Radiometer system to map the cosmic background radiation

    Science.gov (United States)

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

    1978-01-01

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

  6. Far Infrared Spectrometry of the Cosmic Background Radiation

    Science.gov (United States)

    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.

  7. High Precision Cosmology with the Cosmic Background Radiation

    Science.gov (United States)

    Farhang, Marzieh

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

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

    Science.gov (United States)

    Fisenko, Anatoliy I.; Lemberg, Vladimir

    2014-07-01

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

  9. A Cosmic Microwave Background Radiation Polarimeter Using Superconducting Bearings

    CERN Document Server

    Hanany, S; Johnson, B; Jones, T; Hull, J R; Ma, K B

    2003-01-01

    Measurements of the polarization of the cosmic microwave background (CMB) radiation are expected to significantly increase our understanding of the early universe. We present a design for a CMB polarimeter in which a cryogenically cooled half wave plate rotates by means of a high-temperature superconducting (HTS) bearing. The design is optimized for implementation in MAXIPOL, a balloon-borne CMB polarimeter. A prototype bearing, consisting of commercially available ring-shaped permanent magnet and an array of YBCO bulk HTS material, has been constructed. We measured the coefficient of friction as a function of several parameters including temperature between 15 and 80 K, rotation frequency between 0.3 and 3.5 Hz, levitation distance between 6 and 10 mm, and ambient pressure between 10^{-7} and 1 torr. The low rotational drag of the HTS bearing allows rotations for long periods of time with minimal input power and negligible wear and tear thus making this technology suitable for a future satellite mission.

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

    Science.gov (United States)

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

    1994-01-01

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

  11. The Cosmic Background Radiation circa nu2K

    CERN Document Server

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

    2000-01-01

    We describe the implications of cosmic microwave background (CMB) observations and galaxy and cluster surveys of large scale structure (LSS) for theories of cosmic structure formation, especially emphasizing the recent Boomerang and Maxima CMB balloon experiments. The inflation-based cosmic structure formation paradigm we have been operating with for two decades has never been in better shape. Here we primarily focus on a simplified inflation parameter set, {omega_b,omega_{cdm},Omega_{tot}, Omega_\\Lambda,n_s,\\tau_C, \\sigma_8}. Combining all of the current CMB+LSS data points to the remarkable conclusion that the local Hubble patch we can access has little mean curvature (Omega_{tot}=1.08\\pm 0.06) and the initial fluctuations were nearly scale invariant (n_s=1.03\\pm 0.08), both predictions of (non-baroque) inflation theory. The baryon density is found to be slightly larger than that preferred by independent Big Bang Nucleosynthesis estimates (omega_b=0.030\\pm 0.005 cf. 0.019\\pm 0.002). The CDM density is in th...

  12. Dark energy and the cosmic microwave background radiation

    Science.gov (United States)

    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.

  13. The cosmic background radiation circa {nu}2K

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-01-01

    We describe the implications of cosmic microwave background (CMB) observations and galaxy and cluster surveys of large scale structure (LSS) for theories of cosmic structure formation, especially emphasizing the recent Boomerang and Maxima CMB balloon experiments. The inflation-based cosmic structure formation paradigm we have been operating with for two decades has never been in better shape. Here we primarily focus on a simplified inflation parameter set, {l_brace}{omega}{sub b}, {omega}{sub cdm}, {omega}{sub tot}, {omega}{sub {lambda}}, n{sub s}, {tau}{sub C}, {sigma}{sub 8}{r_brace}. Combining all of the current CMB+LSS data points to the remarkable conclusion that the local Hubble patch we can access has little mean curvature ({omega}{sub tot} = 1.08 {+-} 0.06) and the initial fluctuations were nearly scale invariant (n{sub s} 1.03 {+-} 0.08), both predictions of (non-baroque) inflation theory. The baryon density is found to be slightly larger than that preferred by independent Big Bang Nucleosynthesis estimates ({omega}{sub b}-{omega}{sub b}h{sup 2} 0.030 {+-} 0.005 cf. 0.019 {+-} 0.002). The CDM density is in the expected range ({omega}{sub cdm} 0.17{+-}0.02). Even stranger is the CMB+LSS evidence that the density of the universe is dominated by unclustered energy akin to the cosmological constant ({omega}{sub {lambda}} = 0.66 {+-} 0.06), at the same level as that inferred from high redshift supernova observations. We also sketch the CMB+LSS implications for massive neutrinos.

  14. Scientific results from the cosmic background explorer (COBE). [Information on cosmic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, C.L.; Boggess, N.W.; Cheng, E.S.; Hauser, M.G.; Kelsall, T.; Mather, J.C.; Moseley, S.H. Jr.; Shafer, R.A.; Silverberg, R.F. (NASA/Goddard Space Flight Center, Greenbelt, MD (United States)); Murdock, T.L. (General Research Corp., Danvers, MA (United States)); Smoot, G.F. (Lawrence Berkeley Lab., CA (United States)); Weiss, R. (Massachusetts Inst. of Technology, Cambridge (United States)); Wright, E.L. (Univ. of California, Los Angeles (United States))

    1993-06-01

    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 conservation 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. 104 refs., 1 tab.

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

    Energy Technology Data Exchange (ETDEWEB)

    Behne, Patrick Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-08

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Behne, Patrick Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-08

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

  17. Lower Bound on the Cosmic TeV Gamma-ray Background Radiation

    CERN Document Server

    Inoue, Yoshiyuki

    2015-01-01

    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 $3\\times10^{-8} (E/100~{\\rm GeV})^{-0.6} \\exp(-E/2000~{\\rm GeV})~{\\rm [GeV/cm^2/s/sr]} < E^2dN/dE < 1\\times10^{-7} (E/100~{\\rm GeV})^{-0.5}~{\\rm [GeV/cm^2/s/sr]}$, 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 (Inoue & Ioka 2012). Two nearby blazars, Mrk 421 and Mrk 501, explain ~70% of the cumulative flux at 0.8-4 TeV, while extreme blaza...

  18. Mapping the exposure of the Brazilian population to natural background radiation - cosmic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Rochedo, Elaine R.R., E-mail: elaine@ird.gov.br [Instituto de Radioprotecao e Dosimetria (lRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Salles, Krause C.S.; Prado, Nadya M.C., E-mail: krausesalles@yahoo.com.br, E-mail: nadya@ime.ib.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    The main objective of this work is to statically and graphically describe the exposure of the Brazilian population to natural background radiation. in this stage, doses due to cosmic rays is being assessed based on sea level dose rates, corrected by latitude and altitude, according to the model recommended by UNSCEAR. In this work, the doses were estimated for ali Brazilian municipalities with more than 100.000 inhabitants. The 253 municipalities selected for this study include about 52% of the Brazilian population. Average dose rate was estimated to be about 50 n Sv/h with a variation coefficient of 31%. The estimated doses have shown a strong influence of altitude on dose rates, with a correlation coefficient of 0,998 for ao exponential fit. This result confirms previous studies that show a large effect of the altitude 00 exposure from cosmic radiation. Considering the same occupation and shielding conditions used by UNSCEAR as global averages, average annual dose was estimated to be 0,37 (0,24 - 0,76) mSv/y, very close to UNSCEAR worldwide average of 0,38 (0,3 - 1,0) mSv/y. (author)

  19. Measurement of the cosmic background radiation temperature at 6. 3 cm

    Energy Technology Data Exchange (ETDEWEB)

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

    1984-06-15

    We present results of a measurement of the cosmic background radiation temperature at a wavelength of 6.3 cm. We obtained the value T/sub CBR/ = 2.71 +- 0.20 K. This is in good agreement with, and has a smaller error than, any previous measurement at equal or longer wavelengths.

  20. On the Light Speed Anisotropy vs Cosmic Microwave Background Dipole: European Synchrotron Radiation Facility Measurements

    CERN Document Server

    Gurzadyan, V G; Kashin, A; Margarian, A T; Bartalini, O; Bellini, V; Castoldi, M; D'Angelo, A; Didelez, J P; Salvo, R D; Fantini, A; Gervino, G; Ghio, F; Girolami, B; Giusa, A; Guidal, M; Hourany, E; Knyazyan, S; Kouznetsov, V; Kunne, Ronald Alexander; Lapik, A; Levi-Sandri, P; Llères, A; Mehrabyan, S S; Moricciani, D; Nedorezov, V; Perrin, C; Rebreyend, D; Russo, G; Rudnev, N; Schärf, C; Sperduto, M L; Sutera, M C; Turinge, A

    2007-01-01

    The measurement of the Compton edge of the scattered electrons in GRAAL facility in European Synchrotron Radiation Facility (ESRF) in Grenoble with respect to the Cosmic Microwave Background dipole reveals up to 10 sigma variations larger than the statistical errors. We now show that the variations are not due to the frequency variations of the accelerator. The nature of Compton edge variations remains unclear, thus outlining the imperative of dedicated studies of light speed anisotropy.

  1. Probing the Light Speed Anisotropy with respect to the Cosmic Microwave Background Radiation Dipole

    CERN Document Server

    Gurzadyan, V G; Kashin, A L; Margarian, A T; Bartalini, O; Bellini, V; Castoldi, M; D'Angelo, A; Didelez, J P; Salvo, R D; Fantini, A; Gervino, G; Ghio, F; Girolami, B; Giusa, A; Hourany, E; Knyazyan, S; Kuznetsov, V E; Lapik, A; Levi-Sandri, P; Llères, A; Mehrabyan, S S; Moricciani, D; Nedorezov, V; Perrin, C; Rebreyend, D; Russo, G; Rudnev, N; Schärf, C; Sperduto, M L; Sutera, M C; Turinge, A

    2005-01-01

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

  2. Rydberg atom detection of the temporal coherence of cosmic microwave background radiation

    CERN Document Server

    Tscherbul, Timur V

    2013-01-01

    Rydberg atoms immersed in cold blackbody radiation are shown to display long-lived quantum coherence effects on timescales of tens of picoseconds. By solving non-Markovian equations of motion with no free parameters we obtain the time evolution of the density matrix, and demonstrate that the blackbody-induced temporal coherences manifest as quantum beats in time-resolved fluorescence intensities of the Rydberg atoms. A measurable fluorescence signal can be obtained with a cold trapped ensemble of 1e8 Rydberg atoms subject to 2.7 K cosmic microwave background radiation (CMB), allowing for novel insights into previously unexamined quantum coherence properties of CMB.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-04-28

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

  4. Cosmic Microwave Background Radiation Constraints on a Modified Chaplygin Gas Model

    Institute of Scientific and Technical Information of China (English)

    LIU Dao-Jun; LI Xin-Zhou

    2005-01-01

    @@ A modified Chaplygin gas model of unifying dark energy and dark matter with the exotic equation of state p = Bρ- A/ρα , which can also explain the recent expansion of the universe, is investigated by means of constraining the location of the peak of the cosmic microwave background radiation spectrum. We find that the result of CMBR measurements does not exclude the nonzero value of parameter B, but allows it in the range -0.35 (<~) B (<~) 0.025.

  5. Southern Hemisphere Measurement of the Anisotropy in the CosmicMicrowave Background Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Smoot, George F.; Lubin, Phil M.

    1979-06-01

    A recent measurement of the anisotropy in the Cosmic Background Radiation from the southern hemisphere (Lima, Peru) is essentially in agreement with previous measurements from the northern hemisphere. The net anisotropy can be described as a first order spherical harmonic (Doppler) anisotropy of amplitude 3.1 {+-} 0.4 m{sup o}K with a quadrupole anisotropy of less than 1 m{sup o}K. In addition, measurements of the linear polarization yield an upper limit of 1 m{sup o}K, or one part in 3000, at 95% C.L. for the amplitudes of any spherical harmonic through third order.

  6. Primordial Gravitational Waves and Rescattered Electromagnetic Radiation in the Cosmic Microwave Background

    CERN Document Server

    Kim, Dong-Hoon

    2016-01-01

    Understanding the interaction of primordial gravitational waves (GWs) with the Cosmic Microwave Background (CMB) plasma is important for observational cosmology. In this article, we provide an analysis of an effect apparently overlooked as yet. We consider a single free electric charge and suppose that it can be agitated by primordial GWs propagating through the CMB plasma, resulting in periodic, regular motion along particular directions. Light reflected by the charge will be partially polarized, and this will imprint a characteristic pattern on the CMB. We study this effect by considering a simple model in which anisotropic incident electromagnetic (EM) radiation is rescattered by a charge sitting in spacetime perturbed by GWs and becomes polarized. As the charge is driven to move along particular directions, we calculate its dipole moment to determine the leading-order rescattered EM radiation. The Stokes parameters of the rescattered radiation exhibit a net linear polarization. We investigate how this pol...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  9. Small-scale anisotropy of the cosmic background radiation and scattering by cloudy plasma

    CERN Document Server

    Peebles, P J E

    1998-01-01

    If the first stars formed soon after decoupling of baryons from the thermal cosmic background radiation (CBR), the radiation may have been last scattered in a cloudy plasma. We discuss the resulting small-scale anisotropy of the CBR in the limit where the plasma clouds are small compared to the mean distance between clouds along a line of sight. This complements the perturbative analysis valid for mildly nonlinear departures from homogeneity at last scattering. We conclude that reasonable choices for the cloud parameters imply CBR anisotropy consistent with the present experimental limits, in agreement with the perturbative approach. This means the remarkable isotropy of the CBR need not contradict the early small-scale structure formation predicted in some cosmogonies.

  10. Coherent dynamics of Rydberg atoms in cosmic-microwave-background radiation

    Science.gov (United States)

    Tscherbul, Timur V.; Brumer, Paul

    2014-01-01

    Rydberg atoms excited by cold blackbody radiation are shown to display long-lived quantum coherences on time scales of tens of picoseconds. By solving non-Markovian equations of motion with no free parameters we obtain the time evolution of the density matrix and demonstrate that the blackbody-induced temporal coherences manifest as slowly decaying (100 ps) quantum beats in time-resolved fluorescence. An analytic model shows the dependence of the coherent dynamics on the energy splitting between atomic eigenstates, transition dipole moments, and coherence time of the radiation. Experimental detection of the fluorescence signal from a trapped ensemble of 108 Rydberg atoms is discussed, but shown to be technically challenging at present, requiring cosmic-microwave-background amplification somewhat beyond current practice.

  11. On the radiative and thermodynamic properties of the Cosmic Microwave Background radiation using COBE FIRAS instrument data

    CERN Document Server

    Fisenko, Anatoliy I

    2014-01-01

    Use formulas to describe the monopole and dipole spectra of the Cosmic Microwave Background (CMB) radiation, the exact expressions for the temperature dependences of the radiative and thermodynamic functions, such as the total radiation power per unit area, total energy density, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume, pressure, enthalpy density, and internal energy density in the finite range of frequencies are obtained. Since the dependence of temperature upon the redshift z is known, the obtained expressions can be simply presented in z representation. Utilizing experimental data for the monopole and dipole spectra measured by the COBE FIRAS instrument in the 60 - 600 GHz frequency interval at the temperature T = 2.728 K, the values of the radiative and thermodynamic functions, as well as the radiation density constant a and the Stefan-Boltzmann constant are calculated. In the case of the dipole spectrum, the constants a and the Stefan-Bol...

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

    CERN Document Server

    Madau, Piero

    2016-01-01

    We compute the expected X-ray diffuse background and radiative feedback on the intergalactic medium (IGM) from X-ray binaries prior and during the epoch of reionization. The cosmic evolution of compact binaries is followed using a population synthesis technique that treats separately neutron stars and black hole binaries in different spectral states and is calibrated to reproduce the observed X-ray properties of galaxies at z6. Radiative transfer effects modulate the background spectrum, which shows a characteristic peak between 1 and 2 keV. While the filtering of X-ray radiation through the IGM slightly increases the mean excess energy per photoionization, it also weakens the radiation intensity below 1 keV, lowering the mean photoionization and heating rates. Numerical integration of the rate and energy equations shows that the contribution of X-ray binaries to the ionization of the bulk IGM is negligible, with the electron fraction never exceeding 1%. Direct HeI photoionizations are the main source of IGM ...

  13. The Spectrumof the Cosmic Background Radiation: Early and RecentMeasurements from the White Mountain Research Station

    Energy Technology Data Exchange (ETDEWEB)

    Smoot, G.F.

    1985-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1986-02-01

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

  15. Measurement of the large-scale anisotropy of the cosmic background radiation at 3mm

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, G.L.

    1983-12-01

    A balloon-borne differential radiometer has measured the large-scale anisotropy of the cosmic background radiation (CBR) with high sensitivity. The antenna temperature dipole anistropy at 90 GHz (3 mm wavelength) is 2.82 +- 0.19 mK, corresponding to a thermodynamic anistropy of 3.48 +- mK for a 2.7 K blackbody CBR. The dipole direction, 11.3 +- 0.1 hours right ascension and -5.7/sup 0/ +- 1.8/sup 0/ declination, agrees well with measurements at other frequencies. Calibration error dominates magnitude uncertainty, with statistical errors on dipole terms being under 0.1 mK. No significant quadrupole power is found, placing a 90% confidence-level upper limit of 0.27 mK on the RMS thermodynamic quadrupolar anistropy. 22 figures, 17 tables.

  16. The Cosmic Microwave Background

    OpenAIRE

    Silk, Joseph

    2002-01-01

    This set of lectures provides an overview of the basic theory and phenomenology of the cosmic microwave background. Topics include a brief historical review; the physics of temperature and polarization fluctuations; acoustic oscillations of the primordial plasma; the space of inflationary cosmological models; current and potential constraints on these models from the microwave background; and constraints on inflation.

  17. Primordial Gravitational Waves and Rescattered Electromagnetic Radiation in the Cosmic Microwave Background

    Science.gov (United States)

    Kim, Dong-Hoon; Trippe, Sascha

    2016-10-01

    Understanding the interaction of primordial gravitational waves (GWs) with the Cosmic Microwave Background (CMB) plasma is important for observational cosmology. In this article, we provide an analysis of an apparently as-yet-overlooked effect. We consider a single free electric charge and suppose that it can be agitated by primordial GWs propagating through the CMB plasma, resulting in periodic, regular motion along particular directions. Light reflected by the charge will be partially polarized, and this will imprint a characteristic pattern on the CMB. We study this effect by considering a simple model in which anisotropic incident electromagnetic (EM) radiation is rescattered by a charge sitting in spacetime perturbed by GWs, and becomes polarized. As the charge is driven to move along particular directions, we calculate its dipole moment to determine the leading-order rescattered EM radiation. The Stokes parameters of the rescattered radiation exhibit a net linear polarization. We investigate how this polarization effect can be schematically represented out of the Stokes parameters. We work out the representations of gradient modes (E-modes) and curl modes (B-modes) to produce polarization maps. Although the polarization effect results from GWs, we find that its representations, the E- and B-modes, do not practically reflect the GW properties such as strain amplitude, frequency, and polarization states.

  18. Cosmic Microwave Background Mapping

    Science.gov (United States)

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

    2012-03-01

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

  19. An Instrument for Investigation of the Cosmic Microwave Background Radiation at Intermediate Angular Scales

    Science.gov (United States)

    Wollack, E. J.; Devlin, M. J.; Jarosik, N.; Netterfield, C. B.; Page, L.; Wilkinson, D.

    1997-02-01

    We describe an off-axis microwave telescope for observations of the anisotropy in the cosmic microwave background (CMB) radiation on angular scales between 0.5d and 3°. The receiver utilizes cryogenic high electron mobility transistor (HEMT) amplifiers and detects the total power in multiple 3 GHz wide channels. Both frequency and polarization information are recorded allowing discrimination between CMB radiation and potential foreground sources and allowing checks for systematic effects. The instrumental radiometric offset is small (~1 mK). Data are taken by rapidly sampling while sweeping the beam many beamwidths across the sky. After detection, a spatio-temporal filter is formed in software that optimizes the sensitivity in a multipole band in the presence of atmospheric fluctuations. Observations were made from Saskatoon, Saskatchewan (SK), Canada, during the winter of 1993 with six channels between 27.6 and 34.0 GHz, in 1994 with 12 channels between 27.6 and 44.1 GHz, and in 1995 with six channels between 38.2 and 44.1 GHz. The performance of the instrument and assessment of the atmospheric noise at this site are discussed.

  20. High-impedence NbSi TES sensors for studying the cosmic microwave background radiation

    CERN Document Server

    Nones, Claudia; Benoit, Alain; Bergé, Laurent; Bideau, Aurelien; Camus, Philippe; Dumoulin, Louis; Monfardini, Alessandro; Rigaut, Olivier

    2012-01-01

    Precise measurements of the cosmic microwave background (CMB) are crucial in cosmology, because any proposed model of the universe must account for the features of this radiation. Of all CMB measurements that the scientific community has not yet been able to perform, the CMB B-mode polarization is probably the most challenging from the instrumental point of view. The signature of primordial gravitational waves, which give rise to a B-type polarization, is one of the goals in cosmology today and amongst the first objectives in the field. For this purpose, high-performance low-temperature bolometric cameras, made of thousands of pixels, are currently being developed by many groups, which will improve the sensitivity to B-mode CMB polarization by one or two orders of magnitude compared to the Planck satellite HFI detectors. We present here a new bolometer structure that is able to increase the pixel sensitivities and to simplify the fabrication procedure. This innovative device replaces delicate membrane-based s...

  1. The Cosmic Background Explorer Satellite

    Science.gov (United States)

    Mather, J.; Kelsall, T.

    1980-01-01

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

  2. Cosmic microwave background theory.

    Science.gov (United States)

    Bond, J R

    1998-01-06

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

  3. On the radiative and thermodynamic properties of the cosmic radiations using COBE FIRAS instrument data: II. Extragalactic far infrared background radiation

    Science.gov (United States)

    Fisenko, Anatoliy I.; Lemberg, Vladimir

    2014-07-01

    Using formula to describe the average spectrum of the extragalactic far infrared background (FIRB) radiation measured by the COBE FIRAS instrument in the 0.15-2.4 THz frequency interval at mean temperature T=18.5 K, the radiative and thermodynamic properties, such as the total emissivity, total radiation power per unit area, total energy density, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume, and pressure are calculated. The value for the total intensity received in the 0.15-2.4 THz frequency interval is equal to 13.6 nW m-2 sr-1. This value is about 19.4 % of the total intensity expected from the energy released by stellar nucleosynthesis over cosmic history. The radiative and thermodynamic functions of the extragalactic far infrared background (FIRB) radiation are calculated at redshift z=1.5.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jedamzik, Karsten [Laboratoire de Univers et Particules, UMR5299-CNRS, Université de Montpellier II, F-34095 Montpellier (France); Abel, Tom, E-mail: karsten.jedamzik@um2.fr, E-mail: tabel@slac.stanford.edu [Kavli Institute for Particle Astrophysics and Cosmology, SLAC/Stanford University, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2013-10-01

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

  5. The Cosmic Microwave Background Radiation Power Spectrum as a Random Bit Generator for Symmetric and Asymmetric-Key Cryptography

    CERN Document Server

    Lee, Jeffrey S

    2016-01-01

    In this note, the Cosmic Microwave Background (CMB) Radiation is shown to be capable of functioning as a Random Bit Generator, and constitutes an effectively infinite supply of truly random one-time pad values of arbitrary length. It is further argued that the CMB power spectrum potentially conforms to the FIPS 140-2 standard. Additionally, its applicability to the generation of a (n x n) random key matrix for a Vernam cipher is established.

  6. Probing the Cosmic X-Ray and MeV Gamma-Ray Background Radiation through the Anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Yoshiyuki [Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States); Murase, Kohta [Inst. for Advanced Study, Princeton, NJ (United States). School of Natural Sciences; Madejski, Grzegorz M. [Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States); Uchiyama, Yasunobu [Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States); Rikkyo Univ., Tokyo (Japan). Dept. of Physics

    2013-09-24

    While the cosmic soft X-ray background is very likely to originate from individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV gamma-ray background is not fully understood. It is expected that Seyferts including Compton thick population may explain the cosmic hard X-ray background. At MeV energy range, Seyferts having non-thermal electrons in coronae above accretion disks or MeV blazars may explain the background radiation. We propose that future measurements of the angular power spectra of anisotropy of the cosmic X-ray and MeV gamma-ray backgrounds will be key to deciphering these backgrounds and the evolution of active galactic nuclei (AGNs). As AGNs trace the cosmic large-scale structure, spatial clustering of AGNs exists. We show that e-ROSITA will clearly detect the correlation signal of unresolved Seyferts at 0.5-2 keV and 2-10 keV bands and will be able to measure the bias parameter of AGNs at both bands. Once the future hard X-ray all sky satellites achieve the sensitivity better than 10-12 erg/cm2/s-1 at 10-30 keV or 30-50 keV - although this is beyond the sensitivities of current hard X-ray all sky monitors - angular power spectra will allow us to independently investigate the fraction of Compton-thick AGNs in all Seyferts. We also find that the expected angular power spectra of Seyferts and blazars in the MeV range are different by about an order of magnitude, where the Poisson term, so-called shot noise, is dominant. Current and future MeV instruments will clearly disentangle the origin of the MeV gamma-ray background through the angular power spectrum.

  7. Probing the cosmic x-ray and MeV gamma ray background radiation through the anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Yoshiyuki [Stanford Univ., CA (United States); Murase, Kohta [Inst. for Advanced Study, Princeton, NJ (United States); Madejski, Grzegorz M. [Stanford Univ., CA (United States); Uchiyama, Yasunobu [Stanford Univ., CA (United States); Rikkyo Univ., Tokyo (Japan)

    2013-09-24

    While the cosmic soft X-ray background is very likely to originate from individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV gamma-ray background is not fully understood. It is expected that Seyferts including Compton thick population may explain the cosmic hard X-ray background. At MeV energy range, Seyferts having non-thermal electrons in coronae above accretion disks or MeV blazars may explain the background radiation. We propose that future measurements of the angular power spectra of anisotropy of the cosmic X-ray and MeV gamma-ray backgrounds will be key to deciphering these backgrounds and the evolution of active galactic nuclei (AGNs). As AGNs trace the cosmic large-scale structure, spatial clustering of AGNs exists. We show that e-ROSITA will clearly detect the correlation signal of unresolved Seyferts at 0.5-2 keV and 2-10 keV bands and will be able to measure the bias parameter of AGNs at both bands. Once future hard X-ray all sky satellites achieve a sensitivity better than 10–12 erg cm–2 s–1 at 10-30 keV or 30-50 keV—although this is beyond the sensitivities of current hard X-ray all sky monitors—angular power spectra will allow us to independently investigate the fraction of Compton-thick AGNs in all Seyferts. We also find that the expected angular power spectra of Seyferts and blazars in the MeV range are different by about an order of magnitude, where the Poisson term, so-called shot noise, is dominant. Current and future MeV instruments will clearly disentangle the origin of the MeV gamma-ray background through the angular power spectrum.

  8. The Cosmic Microwave Background

    Directory of Open Access Journals (Sweden)

    Jones Aled

    1998-01-01

    Full Text Available We present a brief review of current theory and observations of the cosmic microwave background (CMB. New predictions for cosmological defect theories and an overview of the inflationary theory are discussed. Recent results from various observations of the anisotropies of the microwave background are described and a summary of the proposed experiments is presented. A new analysis technique based on Bayesian statistics that can be used to reconstruct the underlying sky fluctuations is summarised. Current CMB data is used to set some preliminary constraints on the values of fundamental cosmological parameters $Omega$ and $H_circ$ using the maximum likelihood technique. In addition, secondary anisotropies due to the Sunyaev-Zel'dovich effect are described.

  9. High-impedance NbSi TES sensors for studying the cosmic microwave background radiation

    Science.gov (United States)

    Nones, C.; Marnieros, S.; Benoit, A.; Bergé, L.; Bideaud, A.; Camus, P.; Dumoulin, L.; Monfardini, A.; Rigaut, O.

    2012-12-01

    Precise measurements of the cosmic microwave background (CMB) are crucial in cosmology because any proposed model of the universe must account for the features of this radiation. The CMB has a thermal blackbody spectrum at a temperature of 2.725 K, i.e. the spectrum peaks in the microwave range frequency of 160.2 GHz, corresponding to a 1.9-mm wavelength. Of all CMB measurements that the scientific community has not yet been able to perform, the CMB B-mode polarization is probably the most challenging from the instrumental point of view. The signature of primordial gravitational waves, which give rise to a B-type polarization, is one of the goals in cosmology today and amongst the first objectives in the field. For this purpose, high-performance low-temperature bolometric cameras, made of thousands of pixels, are currently being developed by many groups, which will improve the sensitivity to B-mode CMB polarization by one or two orders of magnitude compared to the Planck satellite HFI detectors. We present here a new bolometer structure that is able to increase the pixel sensitivities and to simplify the fabrication procedure. This innovative device replaces delicate membrane-based structures and eliminates the mediation of phonons: the incoming energy is directly captured and measured in the electron bath of an appropriate sensor and the thermal decoupling is achieved via the intrinsic electron-phonon decoupling of the sensor at very low temperature. Reported results come from a 204-pixel array of NbxSi1-x transition edge sensors with a meander structure fabricated on a 2-inch silicon wafer using electron-beam co-evaporation and a cleanroom lithography process. To validate the application of this device to CMB measurements, we have performed an optical calibration of our sample in the focal plane of a dilution cryostat test bench. We have demonstrated a light absorption close to 20% and an optical noise equivalent power of about 7×10-16 W/√Hz, which is highly

  10. Isotropic blackbody cosmic microwave background radiation as evidence for a homogeneous universe.

    Science.gov (United States)

    Clifton, Timothy; Clarkson, Chris; Bull, Philip

    2012-08-03

    The question of whether the Universe is spatially homogeneous and isotropic on the largest scales is of fundamental importance to cosmology but has not yet been answered decisively. Surprisingly, neither an isotropic primary cosmic microwave background (CMB) nor combined observations of luminosity distances and galaxy number counts are sufficient to establish such a result. The inclusion of the Sunyaev-Zel'dovich effect in CMB observations, however, dramatically improves this situation. We show that even a solitary observer who sees an isotropic blackbody CMB can conclude that the Universe is homogeneous and isotropic in their causal past when the Sunyaev-Zel'dovich effect is present. Critically, however, the CMB must either be viewed for an extended period of time, or CMB photons that have scattered more than once must be detected. This result provides a theoretical underpinning for testing the cosmological principle with observations of the CMB alone.

  11. Contamination cannot explain the lack of large-scale power in the cosmic microwave background radiation

    CERN Document Server

    Bunn, Emory F

    2008-01-01

    Several anomalies appear to be present in the large-angle cosmic microwave background (CMB) anisotropy maps of WMAP. One of these is a lack of large-scale power. Because the data otherwise match standard models extremely well, it is natural to consider perturbations of the standard model as possible explanations. We show that, as long as the source of the perturbation is statistically independent of the source of the primary CMB anisotropy, no such model can explain this large-scale power deficit. On the contrary, any such perturbation always reduces the probability of obtaining any given low value of large-scale power. We rigorously prove this result when the lack of large-scale power is quantified with a quadratic statistic, such as the quadrupole moment. When a statistic based on the integrated square of the correlation function is used instead, we present strong numerical evidence in support of the result. The result applies to models in which the geometry of spacetime is perturbed (e.g., an ellipsoidal U...

  12. Constraints on AGN feedback from its Sunyaev-Zel'dovich imprint on the cosmic background radiation

    Science.gov (United States)

    Soergel, Bjoern; Giannantonio, Tommaso; Efstathiou, George; Puchwein, Ewald; Sijacki, Debora

    2017-06-01

    We derive constraints on feedback by active galactic nuclei (AGN) by setting limits on their thermal Sunyaev-Zel'dovich (SZ) imprint on the cosmic microwave background. The amplitude of any SZ signature is small and degenerate with the poorly known sub-mm spectral energy distribution of the AGN host galaxy and other unresolved dusty sources along the line of sight. Here we break this degeneracy by combining microwave and sub-mm data from Planck with all-sky far-infrared maps from the AKARI satellite. We first test our measurement pipeline using the Sloan Digital Sky Survey (SDSS) redMaPPer catalogue of galaxy clusters, finding a highly significant detection (>20σ) of the SZ effect together with correlated dust emission. We then constrain the SZ signal associated with spectroscopically confirmed quasi-stellar objects (QSOs) from SDSS data release 7 (DR7) and the Baryon Oscillation Spectroscopic Survey (BOSS) DR12. We obtain a low-significance (1.6σ) hint of an SZ signal, pointing towards a mean thermal energy of ≃5 × 1060 erg, lower than reported in some previous studies. A comparison of our results with high-resolution hydrodynamical simulations including AGN feedback suggests QSO host masses of M200c ˜ 4 × 1012 h-1 M⊙, but with a large uncertainty. Our analysis provides no conclusive evidence for an SZ signal specifically associated with AGN feedback.

  13. The Inhomogeneous Background of Hydrogen-Molecule Dissociating Radiation during Cosmic Reionization

    CERN Document Server

    Ahn, Kyungjin; Iliev, Ilian T; Mellema, Garrelt; Pen, Ue-Li

    2008-01-01

    The first, self-consistent calculations are presented of the cosmological, H2-dissociating UV background produced during the epoch of reionization by the sources of reionization. Large-scale radiative transfer simulations of reionization trace the impact of all the ionizing starlight on the IGM from all the sources in our simulation volume down to dwarf galaxies of mass ~10^8 Msun, identified by very high-resolution N-body simulations, including the self-regulating effect of IGM photoheating on dwarf galaxy formation. The UV continuum emitted below 13.6 eV by each source is then transferred through the same IGM, attenuated by atomic H Lyman series resonance lines, to predict the evolution of the inhomogeneous radiation background in the Lyman-Werner bands of H2 between 11 and 13.6 eV. On average, the intensity of this Lyman-Werner background is found to rise to the threshold level at which dissociation suppresses H2 cooling and star formation inside minihalos, long before reionization is complete. Spatial var...

  14. The Inhomogeneous Background of H2 Dissociating Radiation During Cosmic Reionization

    CERN Document Server

    Ahn, Kyungjin; Iliev, Ilian T; Mellema, Garrelt; Pen, Ue-Li

    2008-01-01

    The first, self-consistent calculations of the cosmological H_2 dissociating UV background produced during the epoch of reionization (EOR) by the sources of reionization are presented. Large-scale radiative transfer simulations of reionization trace the impact of all the ionizing starlight on the IGM from all the sources in our simulation volume down to dwarf galaxies of mass ~ 10^8 solar mass, identified by very high-resolution N-body simulations, including the self-regulating effect of IGM photoheating on dwarf galaxy formation. The UV continuum emitted below 13.6 eV by each source is then transferred through the same IGM, attenuated by atomic H Lyman series resonance lines, to predict the evolution of the inhomogeneous background in the Lyman-Werner band of H_2 between 11 and 13.6 eV.

  15. Fluctuations of the cosmic background radiation appearing in the 10-dimensional cosmological model

    CERN Document Server

    Tomita, Kenji

    2015-01-01

    We consider a cosmological model starting from (1) the(1+3+6)-dimensional space-times consisting of the outer space (the 3-dimensional expanding section) and the inner space (the 6-dimensional section) and reaching (2) the Friedmann model after the decoupling between the outer space and the inner space, and derive fluctuations of the background radiation appearing in the above 10-dimensional space-times. For this purpose we first derive the fluid-dynamical perturbations in the above 10-dimensional space-times, corresponding to two kinds of curvature perturbations (in the scalar mode) in the non-viscous case, and next study the quantum fluctuations in the scalar and tensor modes, appearing at the stage when the perturbations are within the horizon of the inflating outer space. Lastly we derive the wave-number dependence of fluctuations (the power spectrum) in the two modes, which formed at the above decoupling epoch and are observed in the Friedmann stage. It is found that it can be consistent with the observe...

  16. Anomalies of the Cosmic Microwave Background

    DEFF Research Database (Denmark)

    Hansen, Martin Anders Kirstejn

    The Cosmic Microwave Background (CMB) is the faint afterglow of the extreme conditions that existed shortly after Big Bang. The temperature of the CMB radiation across the sky is extremely uniform, yet tiny anisotropies are present, and have with recent satellite missions been mapped to very high...

  17. Ralph A. Alpher, George Antonovich Gamow, and the Prediction of the Cosmic Microwave Background Radiation

    OpenAIRE

    2014-01-01

    The first prediction of the existence of "relict radiation" or radiation remaining from the "Big Bang" was made in 1948. This derived from the seminal dissertation work of Ralph A. Alpher. He was a doctoral student of George A. Gamow and developed several critical advances in cosmology in late 1946, 1947, and 1948. Alpher developed the ideas of "hot" big bang cosmology to a high degree of physical precision, and was the first to present the idea that radiation, not matter, predominated the ea...

  18. The imprint of the cosmic supermassive black hole growth history on the 21 cm background radiation

    CERN Document Server

    Tanaka, Takamitsu L; Perna, Rosalba

    2015-01-01

    The redshifted 21 cm transition line of hydrogen tracks the thermal evolution of the neutral intergalactic medium (IGM) at "cosmic dawn," during the emergence of the first luminous astrophysical objects (~100 Myr after the Big Bang) but before these objects ionized the IGM (~400-800 Myr after the Big Bang). Because X-rays, in particular, are likely to be the chief energy courier for heating the IGM, measurements of the 21 cm signature can be used to infer knowledge about the first astrophysical X-ray sources. Using analytic arguments and a numerical population synthesis algorithm, we argue that the progenitors of supermassive black holes (SMBHs) should be the dominant source of hard astrophysical X-rays---and thus the primary driver of IGM heating and the 21 cm signature---at redshifts $z 20$. An absence of such a signature in the forthcoming observational data would imply that SMBH formation occurred later (e.g. via so-called direct collapse scenarios), that it was not a common occurrence in early galaxies ...

  19. Spherical Shell Cosmological Model and Uniformity of Cosmic Microwave Background Radiation

    CERN Document Server

    Vlahovic, Branislav

    2012-01-01

    Considered is spherical shell as a model for visible universe and parameters that such model must have to comply with the observable data. The topology of the model requires that motion of all galaxies and light must be confined inside a spherical shell. Consequently the observable universe cannot be defined as a sphere centered on the observer, rather it is an arc length within the volume of the spherical shell. The radius of the shell is 4.46 $\\pm$ 0.06 Gpc, which is for factor $\\pi$ smaller than radius of a corresponding 3-sphere. However the event horizon, defined as the arc length inside the shell, has the size of 14.0 $\\pm$ 0.2 Gpc, which is in agreement with the observable data. The model predicts, without inflation theory, the isotropy and uniformity of the CMB. It predicts the correct value for the Hubble constant $H_0$ = 67.26 $\\pm$ 0.90 km/s/Mpc, the cosmic expansion rate $H(z)$, and the speed of the event horizon in agreement with observations. The theoretical suport for shell model comes from gen...

  20. Radiative transfer in a clumpy universe: IV. New synthesis models of the cosmic UV/X-ray background

    CERN Document Server

    Haardt, Francesco

    2011-01-01

    We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. Five new main components are added to our radiative transfer code CUBA: (1) the sawtooth modulation of the background intensity from resonant line absorption in the Lyman series of cosmic hydrogen and helium; (2) the X-ray emission from obscured and unobscured quasars; (3) a piecewise parameterization of the distribution in redshift and column density of intergalactic absorbers that fits recent measurements of the mean free path of 1 ryd photons; (4) an accurate treatment of the photoionization structure of absorbers; and (5) the UV emission from star-forming galaxies at all redshifts. We provide tables of the predicted HI and HeII photoionization and photoheating rates for use, e.g., in cosmological hydrodynamics simulations of the Lya forest, and a new metallicity-dependent calibration to the UV luminosity density-star formation rate density relation. A "minimal cosm...

  1. Ralph A. Alpher, George Antonovich Gamow, and the Prediction of the Cosmic Microwave Background Radiation

    CERN Document Server

    Alpher, Victor S

    2014-01-01

    The first prediction of the existence of "relict radiation" or radiation remaining from the "Big Bang" was made in 1948. This derived from the seminal dissertation work of Ralph A. Alpher. He was a doctoral student of George A. Gamow and developed several critical advances in cosmology in late 1946, 1947, and 1948. Alpher developed the ideas of "hot" big bang cosmology to a high degree of physical precision, and was the first to present the idea that radiation, not matter, predominated the early universal adiabatic expansion first suggested by A. Friedmann in the early 1920s. Alpher and Herman predicted the residual relic black-body temperature in 1948 and 1949 at around 5 K. However, to this day, this prediction, and other seminal ideas in big bang cosmology, have often been attributed erroneously to the better-known George A. Gamow. This article reviews some of the more egregious and even farcical errors in the scholarly literature about Ralph A. Alpher and his place in the history of big bang cosmology. Tw...

  2. Rings and spots in the structure of the cosmic background radiation

    Energy Technology Data Exchange (ETDEWEB)

    Argueeso, F.; Martinez-Gonzalez, E.; Sanz, J.L.

    1989-01-01

    The influence of a large-scale spherical mass concentration (or void) on the microwave and X-ray backgrounds is studied. Rings and spots in the sky patterns appear due to focusing of the photons, once the monopole and dipole amplitude have been subtracted to avoid contamination by local structures. It is shown how maps over the whole sky can help to identify such a dominant structure. 23 references.

  3. Cosmic Microwave Background Data Analysis

    Science.gov (United States)

    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

  4. Measurements of the anisotropy of the cosmic background radiation and diffuse galactic emission at millimeter and submillimeter wavelengths

    Science.gov (United States)

    Halpern, Mark; Benford, Richard; Meyer, Stephan; Muehlner, Dirk; Weiss, Rainer

    1988-01-01

    The results of a balloon-borne observing program to measure the large angular scale brightness distribution of the 2.7 K cosmic background radiation (CBR) at millimeter and submillimeter wavelengths are reported. A new determination of the dipole anisotropy of the CBR is found with 3.40 + or - 0.42 mK toward alpha = 12.1 + or - 0.24 hr, delta = - 23 + or - 5 deg in a 1.2 to 8/cm band and 4.7 + or - 1.4 mK toward alpha = 9.9 + 1.7 or - 1.1 hr, delta = - 38 + or - 21 deg between 5 and 18/cm, where the amplitudes are listed as thermodynamic temperatures. New estimates of the absolute temperature in these two bands of 2.86 + or - 0.26 K and 3.01 + or - 0.31 are obtained under the assumption that the CBR has a Planck spectrum. The diffuse Galactic emission is fitted by a secant distribution in Galactic latitude, and the resulting Galactic pole antenna temperatures are given. Maps of sky brightness, measurements of zodiacal emission, and measurements of fluctuations of the atmospheric emission which dominates the noise budget are also presented.

  5. Early results from the MIT millimeter and sub-millimeter balloon-borne anisotropy measurement. [of cosmic microwave background radiation

    Science.gov (United States)

    Meyer, Stephan S.; Cheng, Edward S.; Page, Lyman A.

    1991-01-01

    The MIT balloon-borne bolometric search for Cosmic Microwave Background Radiation (CMBR) anisotropies places the most stringent constraints to date on fluctuations in the CMBR. Four maps of half of the Northern Hemisphere at 1.8, 1.1, 0.63 and 0.44 mm wavelength, have a beam size of 3.8 deg with a 1 sigma sensitivity of less than 0.1 mK (thermodynamic) per FOV in each of the first two channels. Analysis of the sky map at 1.8 mm wavelength using a likelihood ratio test for galactic latitudes of 15 deg and greater yields a 95 percent confidence level (CL) upper limit on fluctuations of the CMBR at DeltaT/T less than or equal to 1.6 x 10 exp -5 with a statistical power of 92 percent for Gaussian fluctuations at a correlation angle of 13 deg. Between 3 deg and 22 deg, the upper limit for fluctuations is DeltaT/T less than or equal to 4.0 x 10 exp -5 (95 percent CL).

  6. A Bridge from Optical to Infrared Galaxies Explaining Local Properties, Predicting Galaxy Counts and the Cosmic Background Radiation

    CERN Document Server

    Totani, T; Totani, Tomonori; Takeuchi, Tsutomu T.

    2002-01-01

    We give an explanation for the origin of various properties observed in local infrared galaxies, and make predictions for galaxy counts and cosmic background radiation (CBR), by a new model extended from that for optical/near-infrared galaxies. Important new characteristics of this study are that (1) mass scale dependence of dust extinction is introduced based on the size-luminosity relation of optical galaxies, and that (2) the big grain dust temperature T_dust is calculated based on a physical consideration for energy balance, rather than using the empirical relation between T_dust and total infrared luminosity L_IR found in local galaxies, which has been employed in most of previous works. Consequently, the local properties of infrared galaxies, i.e., optical/infrared luminosity ratios, L_IR-T_dust correlation, and infrared luminosity function are outputs predicted by the model. Our model indeed reproduces these local properties reasonably well. We then found considerably different results for MIR-submm co...

  7. Nonparametric Inference for the Cosmic Microwave Background

    CERN Document Server

    Genovese, C R; Nichol, R C; Arjunwadkar, M; Wasserman, L; Genovese, Christopher R.; Miller, Christopher J.; Nichol, Robert C.; Arjunwadkar, Mihir; Wasserman, Larry

    2004-01-01

    The Cosmic Microwave Background (CMB), which permeates the entire Universe, is the radiation left over from just 380,000 years after the Big Bang. On very large scales, the CMB radiation field is smooth and isotropic, but the existence of structure in the Universe - stars, galaxies, clusters of galaxies - suggests that the field should fluctuate on smaller scales. Recent observations, from the Cosmic Microwave Background Explorer to the Wilkinson Microwave Anisotropy Project, have strikingly confirmed this prediction. CMB fluctuations provide clues to the Universe's structure and composition shortly after the Big Bang that are critical for testing cosmological models. For example, CMB data can be used to determine what portion of the Universe is composed of ordinary matter versus the mysterious dark matter and dark energy. To this end, cosmologists usually summarize the fluctuations by the power spectrum, which gives the variance as a function of angular frequency. The spectrum's shape, and in particular the ...

  8. The Cosmic Infrared Background Experiment

    CERN Document Server

    Bock, J; Cooray, A R; Kawada, M; Keating, B; Lange, A; Lee, D H; Matsumoto, T; Matsuura, S; Pak, S; Renbarger, T; Sullivan, I; Tsumura, K; Wada, T; Watabe, T; Bock, James; Battle, John; Cooray, Asantha; Kawada, Mitsunobu; Keating, Brian; Lange, Andrew; Lee, Dae-Hea; Matsumoto, Toshio; Matsuura, Shuji; Pak, Soojong; Renbarger, Tom; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko; Watabe, Toyoki

    2006-01-01

    We are developing a rocket-borne instrument (the Cosmic Infrared Background ExpeRiment, or CIBER) to search for signatures of primordial galaxy formation in the cosmic near-infrared extra-galactic background. CIBER consists of a wide-field two-color camera, a low-resolution absolute spectrometer, and a high-resolution narrow-band imaging spectrometer. The cameras will search for spatial fluctuations in the background on angular scales from 7 arcseconds to 2 degrees over a range of angular scales poorly covered by previous experiments. CIBER will determine if the fluctuations reported by the IRTS arise from first-light galaxies or have a local origin. In a short rocket flight CIBER has sensitivity to probe fluctuations 100 times fainter than IRTS/DIRBE. By jointly observing regions of the sky studied by Spitzer and ASTRO-F, CIBER will build a multi-color view of the near-infrared background, accurately assessing the contribution of local (z = 1-3) galaxies to the observed background fluctuations, allowing a de...

  9. Anomalies of the Cosmic Microwave Background

    DEFF Research Database (Denmark)

    Hansen, Martin Anders Kirstejn

    the model itself and the derived cosmological parameters, upon which most of the current astronomy and cosmology rests. In order to ascertain whether the anomalies are the results of systematics from the instruments, incomplete data treatment, residuals from foregrounds affecting the measurement of the true......The Cosmic Microwave Background (CMB) is the faint afterglow of the extreme conditions that existed shortly after Big Bang. The temperature of the CMB radiation across the sky is extremely uniform, yet tiny anisotropies are present, and have with recent satellite missions been mapped to very high...... accuracy. The information which the CMB provides has helped in creating the current standard cosmological model - the CDM model - and the theory of cosmic inflation as well as constrain a vast amount of cosmological parameters. The accuracy of observations of the CMB radiation is thus of extreme importance...

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

    CERN Document Server

    Audren, Benjamin; Cuesta, Antonio J; Gontcho, Satya Gontcho A; Lesgourgues, Julien; Niro, Viviana; Pellejero-Ibanez, Marcos; Pérez-Ràfols, Ignasi; Poulin, Vivian; Tram, Thomas; Tramonte, Denis; Verde, Licia

    2015-01-01

    The existence of a cosmic neutrino background can be probed indirectly by CMB experiments, not only by measuring the background density of radiation in the universe, but also by searching for the typical signatures of the fluctuations of free-streaming species in the temperature and polarisation power spectrum. Previous studies have already proposed a rather generic parametrisation of these fluctuations, that could help to discriminate between the signature of ordinary free-streaming neutrinos, or of more exotic dark radiation models. Current data are compatible with standard values of these parameters, which seems to bring further evidence for the existence of a cosmic neutrino background. In this work, we investigate the robustness of this conclusion under various assumptions. We generalise the definition of an effective sound speed and viscosity speed to the case of massive neutrinos or other dark radiation components experiencing a non-relativistic transition. We show that current bounds on these effectiv...

  11. Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds

    Science.gov (United States)

    Schlegel, David J.; Finkbeiner, Douglas P.; Davis, Marc

    1998-06-01

    standard reddening law and use the colors of elliptical galaxies to measure the reddening per unit flux density of 100 μm emission. We find consistent calibration using the B-R color distribution of a sample of the 106 brightest cluster ellipticals, as well as a sample of 384 ellipticals with B-V and Mg line strength measurements. For the latter sample, we use the correlation of intrinsic B-V versus Mg2 index to tighten the power of the test greatly. We demonstrate that the new maps are twice as accurate as the older Burstein-Heiles reddening estimates in regions of low and moderate reddening. The maps are expected to be significantly more accurate in regions of high reddening. These dust maps will also be useful for estimating millimeter emission that contaminates cosmic microwave background radiation experiments and for estimating soft X-ray absorption. We describe how to access our maps readily for general use.

  12. Polarization of Cosmic Microwave Background

    CERN Document Server

    Buzzelli, Alessandro; de Gasperis, Giancarlo; Vittorio, Nicola

    2016-01-01

    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.

  13. The Cosmic Infrared Background Experiment

    Science.gov (United States)

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

    2009-01-01

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

  14. A Cosmic Microwave Background feature consistent with a cosmic texture

    OpenAIRE

    Cruz, M.; Turok, N.; Vielva, P.; Martinez-Gonzalez, E.; Hobson, M.

    2007-01-01

    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 degree radius cold spot observed in all-sky images, which is otherw...

  15. The amplitude and spectral index of the large angular scale anisotropy in the cosmic microwave background radiation

    Science.gov (United States)

    Ganga, Ken; Page, Lyman; Cheng, Edward; Meyer, Stephan

    1994-01-01

    In many cosmological models, the large angular scale anisotropy in the cosmic microwave background is parameterized by a spectral index, n, and a quadrupolar amplitude, Q. For a Harrison-Peebles-Zel'dovich spectrum, n = 1. Using data from the Far Infrared Survey (FIRS) and a new statistical measure, a contour plot of the likelihood for cosmological models for which -1 less than n less than 3 and 0 equal to or less than Q equal to or less than 50 micro K is obtained. Depending upon the details of the analysis, the maximum likelihood occurs at n between 0.8 and 1.4 and Q between 18 and 21 micro K. Regardless of Q, the likelihood is always less than half its maximum for n less than -0.4 and for n greater than 2.2, as it is for Q less than 8 micro K and Q greater than 44 micro K.

  16. Limits on the radiative decay of sterile neutrino dark matter from the unresolved cosmic and soft x-ray backgrounds

    Science.gov (United States)

    Abazajian, Kevork N.; Markevitch, Maxim; Koushiappas, Savvas M.; Hickox, Ryan C.

    2007-03-01

    We present upper limits on line emission in the Cosmic X-ray background (CXB) that would be produced by decay of sterile neutrino dark matter. We employ the spectra of the unresolved component of the CXB in the Chandra Deep Fields North and South obtained with the Chandra CCD detector in the E=0.8 9keV band. The expected decay flux comes from the dark matter on the lines of sight through the Milky Way galactic halo. Our constraints on the sterile neutrino decay rate are sensitive to the modeling of the Milky Way halo. The highest halo mass estimates provide a limit on the sterile neutrino mass of msrocket-borne calorimeter by McCammon and collaborators.

  17. The Temperature of the Cosmic Microwave Background

    CERN Document Server

    Fixsen, D J

    2009-01-01

    The FIRAS data are independently recalibrated using the WMAP data to obtain a CMB temperature of 2.7260 +/- 0.0013. Measurements of the temperature of the cosmic microwave background are reviewed. The determination from the measurements from the literature is cosmic microwave background temperature of 2.72548 +/- 0.00057 K.

  18. The Cosmic Microwave Background anisotropies: open problems

    CERN Document Server

    Martínez-González, E

    2005-01-01

    The standard inflationary model presents a simple scenario within which the homogeneity, isotropy and flatness of the universe appear as natural outcomes and, in addition, fluctuations in the energy density are originated during the inflationary phase. These seminal density fluctuations give rise to fluctuations in the temperature of the Cosmic Microwave Background (CMB) at the decoupling surface. Afterward, the CMB photons propagate almost freely, with slight gravitational interactions with the evolving gravitational field present in the large scale structure (LSS) of the matter distribution and a low scattering rate with free electrons after the universe becomes reionized. These secondary effects slightly change the shape of the intensity and polarization angular power spectra (APS) of the radiation. The APS contain very valuable information on the parameters characterizing the background model of the universe and those parametrising the power spectra of both matter density perturbations and gravitational w...

  19. Limits on the Radiative Decay of Sterile Neutrino Dark Matter from the Unresolved Cosmic and Soft X-ray Backgrounds

    CERN Document Server

    Abazajian, Kevork N; Koushiappas, S M; Hickox, R C; Abazajian, Kevork N.; Markevitch, Maxim; Koushiappas, Savvas M.; Hickox, Ryan C.

    2006-01-01

    We present upper limits on line emission in the Cosmic X-ray background (CXB) that would be produced by decay of sterile neutrino dark matter. We employ the spectra of the unresolved component of the CXB in the Chandra Deep Fields North and South obtained with the Chandra CCD detector in the E=0.8-9 keV band. The expected decay flux comes from the dark matter on the lines of sight through the Milky Way galactic halo. Our constraints on the sterile neutrino decay rate are sensitive to the modeling of the Milky Way halo. The highest halo mass estimates provide a limit on the sterile neutrino mass of m_s<2.9 keV in the Dodelson-Widrow production model, while the lowest halo mass estimates provide the conservative limit of m_s<5.7 keV (2-sigma). We also discuss constraints from a short observation of the softer (E<1 keV) X-ray background with a rocket-borne calorimeter by McCammon and collaborators.

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

    Science.gov (United States)

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

    2007-12-07

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

  1. LiteBIRD: a small satellite for the study of B-mode polarization and inflation from cosmic background radiation detection

    Science.gov (United States)

    Hazumi, M.; Borrill, J.; Chinone, Y.; Dobbs, M. A.; Fuke, H.; Ghribi, A.; Hasegawa, M.; Hattori, K.; Hattori, M.; Holzapfel, W. L.; Inoue, Y.; Ishidoshiro, K.; Ishino, H.; Karatsu, K.; Katayama, N.; Kawano, I.; Kibayashi, A.; Kibe, Y.; Kimura, N.; Koga, K.; Komatsu, E.; Lee, A. T.; Matsuhara, H.; Matsumura, T.; Mima, S.; Mitsuda, K.; Morii, H.; Murayama, S.; Nagai, M.; Nagata, R.; Nakamura, S.; Natsume, K.; Nishino, H.; Noda, A.; Noguchi, T.; Ohta, I.; Otani, C.; Richards, P. L.; Sakai, S.; Sato, N.; Sato, Y.; Sekimoto, Y.; Shimizu, A.; Shinozaki, K.; Sugita, H.; Suzuki, A.; Suzuki, T.; Tajima, O.; Takada, S.; Takagi, Y.; Takei, Y.; Tomaru, T.; Uzawa, Y.; Watanabe, H.; Yamasaki, N.; Yoshida, M.; Yoshida, T.; Yotsumoto, K.

    2012-09-01

    LiteBIRD [Lite (Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection] is a small satellite to map the polarization of the cosmic microwave background (CMB) radiation over the full sky at large angular scales with unprecedented precision. Cosmological inflation, which is the leading hypothesis to resolve the problems in the Big Bang theory, predicts that primordial gravitational waves were created during the inflationary era. Measurements of polarization of the CMB radiation are known as the best probe to detect the primordial gravitational waves. The LiteBIRD working group is authorized by the Japanese Steering Committee for Space Science (SCSS) and is supported by JAXA. It has more than 50 members from Japan, USA and Canada. The scientific objective of LiteBIRD is to test all the representative inflation models that satisfy single-field slow-roll conditions and lie in the large-field regime. To this end, the requirement on the precision of the tensor-to-scalar ratio, r, at LiteBIRD is equal to or less than 0.001. Our baseline design adopts an array of multi-chroic superconducting polarimeters that are read out with high multiplexing factors in the frequency domain for a compact focal plane. The required sensitivity of 1.8μKarcmin is achieved with 2000 TES bolometers at 100mK. The cryogenic system is based on the Stirling/JT technology developed for SPICA, and the continuous ADR system shares the design with future X-ray satellites.

  2. A map of the cosmic microwave background radiation from the Wilkinson Microwave Anisotropy Probe (WMAP), showing the large-scale fluctuations (the quadrupole and octopole) isolated by an analysis done partly by theorists at CERN.

    CERN Multimedia

    2004-01-01

    A recent analysis, in part by theorists working at CERN, suggests a new view of the cosmic microwave background radiation. It seems the solar system, rather than the universe, causes the radiation's large-scale fluctuations, similar to the bass in a song.

  3. CMB anisotropies generated by cosmic voids and great attractors. [Cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Gonzalez, E.; Sanz, J.L. (Cantabria Univ., Santander (Spain). Dept. Fisica Moderna)

    1990-12-01

    A recent result, based on the potential approximation, concerning the effect of a non-static gravitational potential on the propagation of light, is used to study the influence of compensated and uncompensated non-linear structures on the cosmic microwave background radiation. We obtain the temperature profile as well as the deflection of the microwave photons produced by the cosmic voids and great attractors whose existence has recently been claimed in the literature. (author).

  4. First measurements of the polarization of the cosmic microwave background radiation at small angular scales from CAPMAP

    CERN Document Server

    Barkats, D; Farese, P; Fitzpatrick, L; Gaier, T C; Gunderson, J O; Hedman, M M; Hyatt, L; McMahon, J J; Samtleben, D; Staggs, S T; Vanderlinde, K W; Winstein, B

    2004-01-01

    Polarization results from the Cosmic Anisotropy Polarization MAPper (CAPMAP) experiment are reported. These are based upon 433 hours, after cuts, observing a 2 square degree patch around the North Celestial Pole (NCP) with four 90 GHz correlation polarimeters coupled to optics defining $4\\arcmin$ beams. The E-mode flat bandpower anisotropy within $\\ell=940^{+330}_{-300}$ is measured as 66$^{+69}_{-29} \\mu$K$^2$; the 95% Confidence level upper limit for B-mode power within $\\ell=1050^{+590}_{-520}$ is measured as 38 $\\mu$K$^2$.

  5. Fingerprints of Galactic Loop I on the Cosmic Microwave Background

    DEFF Research Database (Denmark)

    Liu, Hao; Mertsch, Philipp; Sarkar, Subir

    2014-01-01

    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...

  6. Fingerprints of Galactic Loop I on the Cosmic Microwave Background

    DEFF Research Database (Denmark)

    Liu, Hao; Mertsch, Philipp; Sarkar, Subir

    2014-01-01

    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...... due to primordial gravitational waves from inflation....

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

    Energy Technology Data Exchange (ETDEWEB)

    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. (NASA, Goddard Space Flight Center, Greenbelt, MD (USA))

    1990-05-01

    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. 31 refs.

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

    Science.gov (United States)

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

    Science.gov (United States)

    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.

  10. Can one measure the Cosmic Neutrino Background?

    CERN Document Server

    Faessler, Amand; Kovalenko, Sergey; Simkovic, Fedor

    2016-01-01

    The Cosmic Microwave Background (CMB) yields information about our Universe at around 380 000 years after the Big Bang (BB). Due to the weak interaction of the neutrinos with matter the Cosmic Neutrino Background (CNB) should give information about a much earlier time of our Universe, around one second after the Big Bang. Probably the most promising method to `see' the Cosmic Neutrino Background is the capture of the electron neutrinos from the Background by Tritium, which then decays into 3He and an electron with the energy of the the Q-value = 18.562 keV plus the electron neutrino rest mass. The `KArlsruhe TRItium Neutrino' (KATRIN) experiment, which is in preparation, seems presently the most sensitive proposed method for measuring the electron antineutrino mass. At the same time KATRIN can also look by the reaction: electron neutrino (~1.95 Kelvin) + 3H --> 3He + e- (with the energy Q = 18.6 keV + electron neutrino mass). The capture of the Cosmic Background Neutrinos (CNB) should show in the electron spe...

  11. Spectral measurements of the cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Hydrology and Cosmic radiation

    DEFF Research Database (Denmark)

    Andreasen, Mie

    and calibration. Yet, soil moisture measurements are traditionally provided on either point or kilometer scale from electromagnetic based sensors and satellite retrievals, respectively. Above the ground surface, the cosmic-ray neutron intensity (eV range) is inversely correlated to all hydrogen present...

  13. Neutrino refraction by the cosmic neutrino background

    CERN Document Server

    Diaz, J S

    2015-01-01

    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.

  14. A Detector for Cosmic Microwave Background Polarimetry

    Science.gov (United States)

    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.

  15. Gravitational Lensing of Cosmic Microwave Background Polarization

    CERN Document Server

    Ade, P A R; Anthony, A E; Arnold, K; Barron, D; Boettger, D; Borrill, J; Chapman, S; Chinone, Y; Dobbs, M; Elleflot, T; Errard, J; Fabbian, G; Feng, C; Flanigan, D; Gilbert, A; Grainger, W; Halverson, N W; Hasegawa, M; Hattori, K; Hazumi, M; Holzapfel, W L; Hori, Y; Howard, J; Hyland, P; Inoue, Y; Jaehnig, G C; Jaffe, A; Keating, B; Kermish, Z; Keskitalo, R; Kisner, T; Jeune, M Le; Lee, A T; 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; Quealy, E; Rebeiz, G; Reichardt, C L; Richards, P L; Ross, C; Schanning, I; Schenck, D E; Sherwin, B; Shimizu, A; Shimmin, C; Shimon, M; Siritanasak, P; Smecher, G; Spieler, H; Stebor, N; Steinbach, B; Stompor, R; Suzuki, A; Takakura, S; Tomaru, T; Wilson, B; Yadav, A; Zahn, O

    2013-01-01

    Primary fluctuations in both temperature and polarization of the Cosmic Microwave Background (CMB) reflect the properties of the Universe from the Big Bang until the photons decoupled from matter 380,000 years later. These primary fluctuations are then lensed by large-scale structures (such as clusters of galaxies and filaments of dark matter), with the result that the distribution and properties of dark matter, including the masses of neutrinos, can be determined more accurately by extracting the lensing information than through studying the primary fluctuations alone. Polarization lensing can give cleaner, higher resolution results than temperature lensing. The correlation of lensed CMB polarization with large-scale structure, traced through the Cosmic Infrared Background, was recently detected; however, this correlation does not trace all structure and depends on the relationship between the infrared flux from the galaxies and the underlying mass distribution. Here we report the detection of gravitational ...

  16. A Detector for Cosmic Microwave Background Polarimetry

    Science.gov (United States)

    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.

  17. Cosmic Rays and Radiative Instabilities

    CERN Document Server

    Hartquist, T W; Falle, S A E G; Pittard, J M; Van Loo, S

    2011-01-01

    In the absence of magnetic fields and cosmic rays, radiative cooling laws with a range of dependences on temperature affect the stability of interstellar gas. For about four and a half decades, astrophysicists have recognised the importance of the thermal instablity for the formation of clouds in the interstellar medium. Even in the past several years, many papers have concerned the role of the thermal instability in the production of molecular clouds. About three and a half decades ago, astrophysicists investigating radiative shocks noticed that for many cooling laws such shocks are unstable. Attempts to address the effects of cosmic rays on the stablity of radiative media that are initially uniform or that have just passed through shocks have been made. The simplest approach to such studies involves the assumption that the cosmic rays behave as a fluid. Work based on such an approach is described. Cosmic rays have no effect on the stability of initially uniform, static media with respect to isobaric perturb...

  18. The Cosmic Microwave Background State of the Art

    CERN Document Server

    Barreiro, R B

    2000-01-01

    We review the current status of the cosmic microwave background (CMB) radiation, including a revision of some basic theoretical aspects, a summary of anisotropy detections and CMB experiments, and a description of some relevant characteristics of the microwave foregrounds. We also discuss the different estimators proposed in the literature to detect non-Gaussianity and outline the basis of some reconstruction methods that have been applied to the CMB.

  19. The near-infrared radiation background, gravitational wave background and star formation rate of Pop III and Pop II during cosmic reionization

    CERN Document Server

    Yang, Y P; Dai, Z G

    2015-01-01

    In this paper, we obtain the NIRB and SBGWs from the early stars, which are constrained by the observation of reionization and star formation rate. We study the transition from Pop III to Pop II stars via the star formation model of different population, which takes into account the reionization and the metal enrichment evolution. We calculate the two main metal pollution channels arising from the supernova-driven protogalactic outflows and "genetic channel". We obtain the SFRs of Pop III and Pop II and their NIRB and SBGWs radiation. We predict that the upper limit of metallicity in metal-enriched IGM (the galaxies whose polluted via "genetic channel") reaches $Z_{\\rm crit}=10^{-3.5}Z_{\\odot}$ at $z\\sim13$ ($z\\sim11$), which is consistent with our star formation model. We constrain on the SFR of Pop III stars from the observation of reionization. The peak intensity of NIRB is about $0.03-0.2~nW m^{-2}{sr}^{-1}$ at $\\sim 1 \\mu m$ for $z>6$. The prediction of NIRB signal is consistent with the metallicity evol...

  20. Sunyaev-Zeldovich and Cosmic Microwave Background

    CERN Document Server

    Burigana, Carlo

    2007-01-01

    Since its original formulation the Sunyaev-Zeldovich (SZ) effect has been recognized as a ``powerful laboratory'' for our comprehension of physical processes in cosmic structures and to derive crucial information on some general properties of the universe. After a discussion of the fundamental concepts and of some well established applications of the SZ effect towards galaxy clusters, I will focus on dedicated themes related to the SZ effect and other features in the cosmic microwave background (CMB) of particular interest in the view of the extremely high angular resolution observations achievable in the future with the Square Kilometre Array (SKA). SKA will allow the mapping of the thermal and density structure of clusters of galaxies at radio and centimetre bands with unprecedented resolution and sensitivity and with an extremely accurate control of extragalactic radio source contamination. The signatures from SZ effects and free-free emission at galactic scales and in the intergalactic medium probe the st...

  1. X-Ray Ccds for Space Applications: Calibration, Radiation Hardness, and Use for Measuring the Spectrum of the Cosmic X-Ray Background

    Science.gov (United States)

    Gendreau, Keith Charles

    1995-01-01

    This thesis has two distinct components. One concerns the physics of the high energy resolution X-ray charge coupled devices (CCD) detectors used to measure the cosmic X-ray background (XRB) spectrum. The other involves the measurements and analysis of the XRB spectrum and instrumental background with these detectors on board the advanced satellite for cosmology and astrophysics (ASCA). The XRB has a soft component and a hard component divided at ~2 keV. The hard component is extremely isotropic, suggesting a cosmological origin. The soft component is extremely anisotropic. A galactic component most likely dominates the soft band with X-ray line emission due to a hot plasma surrounding the solar system. ASCA is one of the first of a class of missions designed to overlap the hard and soft X-ray bands. The X-ray CCD's energy resolution allows us to spectrally separate the galactic and cosmological components. Also, the resolution offers the ability to test several specific cosmological models which would make up the XRB. I have concentrated on models for the XRB origin which include active galactic nuclei (AGN) as principal components. I use ASCA data to put spectral constraints on the AGN synthesis model for the XRB. The instrumental portion of this thesis concerns the development and calibration of the X-ray CCDs. I designed, built and operated an X-ray calibration facility for these detectors. It makes use of a reflection grating spectrometer to measure absolute detection efficiency, characteristic absorption edge strengths, and spectral redistribution in the CCD response function. Part of my thesis research includes a study of radiation damage mechanisms in CCDs. This work revealed radiation damage-induced degradation in the spectral response to X-rays. It also uncovered systematic effects which affect both data analysis and CCD design. I have developed a model involving trap energy levels in the CCD band gap structure. These traps reduce the efficiency in which

  2. Cross correlations of the cosmic infrared background

    CERN Document Server

    Zhang, P

    2003-01-01

    Cosmic infrared background (CIB) is a sensitive measure of the structure formation of the universe, especially the star formation history. But this background is overwhelmed by foregrounds. The cross correlation of CIB with galaxies is able to eliminate such foregrounds, minimize and localize several backgrounds which could bias the study of the star formation history. The cross correlation study of CIB has three advantages. (1) Combining the galaxy photometric redshift information, it directly measures the structure formation history. (2) The sky area used for CIB analysis is no long limited to the relatively clean sky. The utilization of CIB full sky data minimizes the sample variance. (3) The CIB measurement is no longer limited to several narrow frequency windows. This allows the measurement of CIB based on integrated intensity, whose theoretical prediction is based on energy conservation, thus is fairly model independent and robust. The cross correlation can be measured with 10% accuracy (statistical and...

  3. Cosmic Neutrino Background as a Ferromagnet

    CERN Document Server

    Arias, Paola; Lopez-Sarrion, Justo

    2013-01-01

    If cosmic background neutrinos interact very weakly with each other, through spin-spin interactions, then they may have experienced a phase transition, leading to a ferromagnetic ordering. The small magnetic field resulting from ferromagnetic ordering -- if present before galaxy formation -- could act as a primordial seed of the magnetic fields observed in several galaxies. Our findings suggest that the magnetization could occur in the right epoch, if the exchange gauge boson of neutrino-neutrino interaction is a massless boson beyond the Standard Model, with a coupling constant of $2.2\\times 10^{-13} \\left(\\frac{m_\

  4. Cosmic X-ray background and solitars.

    Science.gov (United States)

    Chiu, H.-Y.

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

  5. Superhorizon Perturbations and the Cosmic Microwave Background

    CERN Document Server

    Erickcek, Adrienne L; Kamionkowski, Marc

    2008-01-01

    Superhorizon perturbations induce large-scale temperature anisotropies in the cosmic microwave background (CMB) via the Grishchuk-Zel'dovich effect. We analyze the CMB temperature anisotropies generated by a single-mode adiabatic superhorizon perturbation. We show that an adiabatic superhorizon perturbation in a LCDM universe does not generate a CMB temperature dipole, and we derive constraints to the amplitude and wavelength of a superhorizon potential perturbation from measurements of the CMB quadrupole and octupole. We also consider constraints to a superhorizon fluctuation in the curvaton field, which was recently proposed as a source of the hemispherical power asymmetry in the CMB.

  6. Fingerprints of Galactic Loop I on the Cosmic Microwave Background

    CERN Document Server

    Liu, Hao; Sarkar, Subir

    2014-01-01

    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 polarisation signal due to primordial gravitational waves from inflation.

  7. Cosmic axion background propagation in galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Day, Francesca V., E-mail: francesca.day@physics.ox.ac.uk

    2016-02-10

    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.

  8. Bayesian Analysis of the Cosmic Microwave Background

    Science.gov (United States)

    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.

  9. Data analysis of cosmic microwave background experiments

    Science.gov (United States)

    Abroe, Matthew Edmund

    2004-12-01

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

  10. Physics of the cosmic microwave background anisotropy

    CERN Document Server

    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 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.

  11. Systematic distortion in cosmic microwave background maps

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    To minimize instrumentally the induced systematic errors,cosmic microwave background(CMB)anisotropy experiments measure temperature differences across the sky using pairs of horn antennas, temperature map is recovered from temperature difference obtained in sky survey through a map-making procedure.To inspect and calibrate residual systematic errors in the recovered temperature maps is important as most previous studies of cosmology are based on these maps.By analyzing pixel-ring coupling and latitude dependence of CMB temperatures,we find notable systematic devia- tion from CMB Gaussianity in released Wilkinson Microwave Anisotropy Probe(WMAP)maps.The detected deviation cannot be explained by the best-fit LCDM cosmological model at a confidence level above 99%and cannot be ignored for a precision cosmology study.

  12. Nonlinear Effects in the Cosmic Microwave Background

    CERN Document Server

    Maartens, R

    2000-01-01

    Major advances in the observation and theory of cosmic microwave background anisotropies have opened up a new era in cosmology. This has encouraged the hope that the fundamental parameters of cosmology will be determined to high accuracy in the near future. However, this optimism should not obscure the ongoing need for theoretical developments that go beyond the highly successful but simplified standard model. Such developments include improvements in observational modelling (e.g. foregrounds, non-Gaussian features), extensions and alternatives to the simplest inflationary paradigm (e.g. non-adiabatic effects, defects), and investigation of nonlinear effects. In addition to well known nonlinear effects such as the Rees-Sciama and Ostriker-Vishniac effects, further nonlinear effects have recently been identified. These include a Rees-Sciama-type tensor effect, time-delay effects of scalar and tensor lensing, nonlinear Thomson scattering effects and a nonlinear shear effect. Some of the nonlinear effects and th...

  13. Cosmological Constraints from the Cosmic Microwave Background

    CERN Document Server

    Le Dour, M D M; Bartlett, J G; Blanchard, A

    2000-01-01

    Using an approximate likelihood method adapted to band-power estimates, we analyze the ensemble of first generation cosmic microwave background anisotropy experiments to deduce constraints over a six-dimensional parameter space describing Inflation-generated adiabatic, scalar fluctuations. The basic preferences of simple Inflation scenarios are consistent with the data set: flat geometries $(\\OmT \\equiv 1-\\Omk \\sim 1)$ and a scale-invariant primeval spectrum ($n\\sim 1$) are favored. Models with significant negative curvature ($\\OmT < 0.7$) are eliminated, while constraints on postive curvature are less stringent. Degeneracies among the parameters prevent independent determinations of the matter density $\\OmM$ and the cosmological constant $\\Lambda$, and the Hubble constant $\\Ho$ remains relatively unconstrained. We also find that the relative height of the first Doppler peak suggests a high baryon content ($\\Omb h^2$), almost independently of the other parameters; besides the overall qualitative advance ex...

  14. Cosmic Microwave Background Acoustic Peak Locations

    CERN Document Server

    Pan, Zhen; Mulroe, Brigid; Narimani, Ali

    2016-01-01

    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 twelve 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 degrees out of phase. However, there are large differences in expectations for extrema locations from simple analytic models vs. numerical calculations. Here we quantitatively explore the origin of these differences in gravitational potential tr...

  15. Cosmic axion background propagation in galaxies

    Directory of Open Access Journals (Sweden)

    Francesca V. Day

    2016-02-01

    Full Text Available 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.

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

    Science.gov (United States)

    Danos, Rebecca J.; Brandenberger, Robert H.

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

  17. Cosmic Infrared Background Fluctuations and Zodiacal Light

    Science.gov (United States)

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

    2017-01-01

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

  18. Cosmic Infrared Background Fluctuations and Zodiacal Light

    Science.gov (United States)

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

    2017-01-01

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

  19. Self-Similar Symmetry Model and Cosmic Microwave Background

    Directory of Open Access Journals (Sweden)

    Tomohide eSonoda

    2016-05-01

    Full Text Available In this paper, we present the self-similar symmetry (SSS model that describes the hierarchical structure of the universe. The model is based on the concept of self-similarity, which explains the symmetry of the cosmic microwave background (CMB. The approximate length and time scales of the six hierarchies of the universe---grand unification, electroweak unification, the atom, the pulsar, the solar system, and the galactic system---are derived from the SSS model. In addition, the model implies that the electron mass and gravitational constant could vary with the CMB radiation temperature.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Signore, Monique [LERMA, Observatoire de Paris, Paris (France); Puy, Denis [University of Montpellier II, CNRS UMR 5024, GRAAL CC72, Montpellier (France)

    2009-01-15

    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. (orig.)

  3. Probing inflation with the cosmic microwave background

    Science.gov (United States)

    Braganca, Vinicius Miranda

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

  4. Statistics of cosmic microwave background polarization

    Energy Technology Data Exchange (ETDEWEB)

    Kamionkowski, M. [Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027 (United States); Kosowsky, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States)]|[Department of Physics, Lyman Laboratory, Harvard University, Cambridge, Massachusetts 02138 (United States); Stebbins, A. [NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States)

    1997-06-01

    We present a formalism for analyzing a full-sky temperature and polarization map of the cosmic microwave background. Temperature maps are analyzed by expanding over the set of spherical harmonics to give multipole moments of the two-point correlation function. Polarization, which is described by a second-rank tensor, can be treated analogously by expanding in the appropriate tensor spherical harmonics. We provide expressions for the complete set of temperature and polarization multipole moments for scalar and tensor metric perturbations. Four sets of multipole moments completely describe isotropic temperature and polarization correlations; for scalar metric perturbations one set is identically zero, giving the possibility of a clean determination of the vector and tensor contributions. The variance with which the multipole moments can be measured in idealized experiments is evaluated, including the effects of detector noise, sky coverage, and beam width. Finally, we construct coordinate-independent polarization two-point correlation functions, express them in terms of the multipole moments, and derive small-angle limits. {copyright} {ital 1997} {ital The American Physical Society}

  5. Statistics of cosmic microwave background polarization

    Energy Technology Data Exchange (ETDEWEB)

    Kamionkowski, Marc; Kosowsky, Arthur; Stebbins, Albert

    1996-11-01

    We present a formalism for analyzing a full-sky temperature and polarization map of the cosmic microwave background. Temperature maps are analyzed by expanding over the set of spherical harmonics to give multipole moments of the two-point correlation function. Polarization, which is described by a second-rank tensor, can be treated analogously by expanding in the appropriate tensor spherical harmonics. We provide expressions for the complete set of temperature and polarization multipole moments for scalar and tensor metric perturbations. Four sets of multipole moments completely describe isotropic temperature and polarization correlations; for scalar metric perturbations one set is identically zero, giving the possibility of a clean determination of the vector and tensor contributions. The variance with which the multipole moments can be measured in idealized experiments is evaluated, including the effects of detector noise, sky coverage, and beam width. Finally, we construct coordinate-independent polarization two-point correlation functions, express them in terms of the multipole moments, and derive small-angle limits.

  6. Cosmic axion background propagation in galaxies

    CERN Document Server

    Day, Francesca V

    2015-01-01

    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 prob...

  7. Probing Inflation via Cosmic Microwave Background Polarimetry

    Science.gov (United States)

    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.

  8. Cosmic Microwave Background Temperature at Galaxy Clusters

    CERN Document Server

    Battistelli, E S; Lamagna, L; Melchiorri, F; Palladino, E; Savini, G; Cooray, A R; Melchiorri, A; Rephaeli, Y; Shimon, M

    2002-01-01

    We have deduced the cosmic microwave background (CMB) temperature in the Coma cluster (Abell 1656, z=0.0231), and in Abell 2163 (z=0.203) from spectral measurements of the Sunyaev-Zel'dovich (SZ) effect over four passbands at radio and microwave frequencies. The resulting temperatures at these redshifts are T_{Coma} = 2.750^{+0.043}_{-0.032} K and T_{A2163} = 3.335^{+0.065}_{-0.066} K, respectively. These values are in good agreement with the basic relation T(z)=T_{0}(1+z), where T_{0} = (2.725 +/- 0.002) K as measured by the COBE/FIRAS experiment. Alternative scaling relations that are conjectured in non-standard cosmologies can be constrained by the data; for example, if T(z) = T_{0}(1+z)^{1-a} or T(z)=T_0[1+(1+d)z], then a=-0.07^{+0.12}_{-0.11} and d = 0.07 +/- 0.12. We briefly discuss future prospects for more precise SZ measurements of T(z) at higher redshifts.

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

    CERN Document Server

    Tsumura, K; 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

    2011-01-01

    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 (CIBER) is a \\lambda / \\Delta \\lambda \\sim 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 a...

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

    Science.gov (United States)

    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 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.

  11. The Hard VHE Gamma-ray Emission in High-Redshift TeV Blazars: Comptonization of Cosmic Microwave Background Radiation in an Extended Jet?

    CERN Document Server

    Boettcher, Markus; Finke, Justin D

    2008-01-01

    Observations of very-high-energy (VHE, E > 250 GeV) gamma-ray emission from several blazars at z > 0.1 have placed stringent constraints on the elusive spectrum and intensity of the intergalactic infrared background radiation (IIBR). Correcting their observed VHE spectrum for gamma-gamma absorption even by the lowest plausible level of the IIBR provided evidence for a very hard (photon spectral index Gamma_{ph} 4 X 10^6) on kiloparsec scales along the jet.

  12. Radiative Feedback Effects during Cosmic Reionization

    Science.gov (United States)

    Sullivan, David; Iliev, Ilian T.

    2016-10-01

    We present coupled radiation hydrodynamical simulations of the epoch of reionization, aimed at probing self-feedback on galactic scales. Unlike previous works, which assume a (quasi) homogeneous UV background, we self-consistently evolve both the radiation field and the gas to model the impact of previously unresolved processes such as spectral hardening and self-shielding. We find that the characteristic halo mass with a gas fraction half the cosmic mean, Mc (z), a quantity frequently used in semi-analytical models of galaxy formation, is significantly larger than previously assumed. While this results in an increased suppression of star formation in the early Universe, our results are consistent with the extrapolated stellar abundance matching models from Moster et al. 2013.

  13. Modelling the uv/x-ray cosmic background with CUBA

    CERN Document Server

    Haardt, F; Haardt, Francesco; Madau, Piero

    2001-01-01

    In this paper, I will describe the features of the numerical code CUBA, aimed at the solution of the radiative transfer equation in a cosmological context. CUBA will be soon available for public use at the URL http://pitto.mib.infn.it/~haardt/, allowing for several user-supplied input parameters, such as favourite cosmology, luminosity functions, Type II object evolution, stellar spectra, and many others. I will also present some new results of the UV/X-ray cosmic background as produced by the observed populations of QSOs and star forming galaxies, updating and extending our previous works. The background evolution is complemented with a number of derived quantities such as the ionization and thermal state of the IGM, the HeII opacity, the HI and HeII ionization rates, and the HI, HeII and Compton heating rates.

  14. Radiation from cosmic string standing waves

    Science.gov (United States)

    Olum; Blanco-Pillado

    2000-05-01

    We have simulated large-amplitude standing waves on an Abelian-Higgs cosmic string in classical lattice field theory. The radiation rate falls exponentially with wavelength, as one would expect from the field profile around a gauge string. Our results agree with those of Moore and Shellard, but not with those of Vincent, Antunes, and Hindmarsh. The radiation rate falls too rapidly to sustain a scaling solution via direct radiation of particles from string length. There is thus reason to doubt claims of strong constraints on cosmic string theories from cosmic ray observations.

  15. Ultraviolet Background Radiation (Preprint)

    Science.gov (United States)

    1991-03-01

    importance is that the sky may be truly outstandingly black in the far ultraviolet, offering a "dark site " that is unprecedented in astronomy...Estimated spectral energy distribution of the night-sky background near the zenith at an excellent ground-based site on a moonless night and in a...1977. Ap. J. Suppl. 33:451 31. Henry, R. C. 1981. Ap. J. Lett. 244: L69 32. Henry, R. C. 1981. 16th Rencontre de Moriond, ed. J. Tran Thanh Van, p

  16. Cosmic Connections:. from Cosmic Rays to Gamma Rays, Cosmic Backgrounds and Magnetic Fields

    Science.gov (United States)

    Kusenko, Alexander

    2013-12-01

    Combined data from gamma-ray telescopes and cosmic-ray detectors have produced some new surprising insights regarding intergalactic and galactic magnetic fields, as well as extragalactic background light. We review some recent advances, including a theory explaining the hard spectra of distant blazars and the measurements of intergalactic magnetic fields based on the spectra of distant sources. Furthermore, we discuss the possible contribution of transient galactic sources, such as past gamma-ray bursts and hypernova explosions in the Milky Way, to the observed ux of ultrahigh-energy cosmicrays nuclei. The need for a holistic treatment of gamma rays, cosmic rays, and magnetic fields serves as a unifying theme for these seemingly unrelated phenomena.

  17. Galactic cosmic radiation environment models

    Science.gov (United States)

    Badhwar, G. D.; O'Neill, P. M.; Troung, A. G.

    2001-02-01

    Models of the radiation environment in free space and in near earth orbits are required to estimate the radiation dose to the astronauts for Mars, Space Shuttle, and the International Space Station missions, and to estimate the rate of single event upsets and latch-ups in electronic devices. Accurate knowledge of the environment is critical for the design of optimal shielding during both the cruise phase and for a habitat on Mars or the Moon. Measurements of the energy spectra of galactic cosmic rays (GCR) have been made for nearly four decades. In the last decade, models have been constructed that can predict the energy spectra of any GCR nuclei to an accuracy of better than 25%. Fresh and more accurate measurements have been made in the last year. These measurements can lead to more accurate models. Improvements in these models can be made in determining the local interstellar spectra and in predicting the level of solar modulation. It is the coupling of the two that defines a GCR model. This paper reviews of two of the more widely used models, and a comparison of their predictions with new proton and helium data from the Alpha Magnetic Spectrometer (AMS), and spectra of beryllium to iron in the ~40 to 500 MeV/n acquired by the Advanced Composition Explorer (ACE) during the 1997-98 solar minimum. Regressions equations relating the IMP-8 helium count rate to the solar modulation deceleration parameter calculated using the Climax neutron monitor rate have been developed and may lead to improvements in the predictive capacity of the models. .

  18. Ultraviolet Background Radiation

    Science.gov (United States)

    Henry, R. C.; Murthy, J.

    1993-12-01

    The UVX experiment was carried on the Space Shuttle Columbia between 1986 January 12 and 19 (STS-61C). Several ultraviolet spectrometers were used to obtain measurements of the diffuse ultraviolet background at 8 locations in the sky. We have reanalysed the UVX measurements of the surface brightness of the diffuse ultraviolet background above b = 40 using the dust-scattering model of Onaka & Kodaira (1991), which explicitly takes into account the variation of the source function with galactic longitude. The range of allowed values of interstellar grain albedoJa, and scattering asymmetry parameter g, is considerably expanded over those of a previous analysis. The new chi square probability contours come close to, but do not include, the values of a and g found for the interstellar grains by Witt et al. (1992) using the Ultraviolet Imaging Telescope (UIT) on the Astro mission. If we hypothesize in additon to the dust-scattered light an extragalactic component, of 300 1 100 photons cm-2 s-1 sr-1 A-1, attenuated by a cosecant b law, the new reduction of the UVX data gives complete consistency with the Witt et al. determination of the optical parameters of the grains in the ultraviolet. This work was supported by United States Air Force Contract F19628-93-K-0004, and by National Aeronautics and Space Administration grant NASA NAG5-619. We are grateful for the encouragement of Dr. Stephan Price, and we thank Dr. L. Danly for information. Onaka, T., & Kodaira, K. 1991, ApJ, 379, 532 Witt, A. N., Petersohn, J. K., Bohlin, R. C., O'Connell, R. W., Roberts, M. S., Smith, A. M., & Stecher, T. P. 1992, ApJ, 395, L5

  19. Large Scale Anomalies of the Cosmic Microwave Background with Planck

    DEFF Research Database (Denmark)

    Frejsel, Anne Mette

    This thesis focuses on the large scale anomalies of the Cosmic Microwave Background (CMB) and their possible origins. The investigations consist of two main parts. The first part is on statistical tests of the CMB, and the consistency of both maps and power spectrum. We find that the Planck data...... is very consistent, while the WMAP 9 year release appears more contaminated by non-CMB residuals than the 7 year release. The second part is concerned with the anomalies of the CMB from two approaches. One is based on an extended inflationary model as the origin of one specific large scale anomaly, namely....... Here we find evidence that the Planck CMB maps contain residual radiation in the loop areas, which can be linked to some of the large scale CMB anomalies: the point-parity asymmetry, the alignment of quadrupole and octupole and the dipolemodulation....

  20. Spectator fields and their imprints on the Cosmic Microwave Background

    CERN Document Server

    Wang, Lingfei

    2016-01-01

    When a subdominant light scalar field ends slow roll during inflation, but well after the Hubble exit of the pivot scales, it may determine the cosmological perturbations. This thesis investigates how such a scalar field, the spectator, may leave its impact on the Cosmic Microwave Background (CMB) radiation and be consequently constrained. We first introduce the observables of the CMB, namely the power spectrum $P_\\zeta$, spectral index $n_s$ and its running $dn_s/d\\ln k$, the non-Gaussianities $f_{NL}$, $g_{NL}$ and $\\tau_{NL}$, and the lack of isocurvature and polarization modes. Based on these studies, we derive the cosmological predictions for the spectator scenario, revealing its consistency with the CMB for inflection point potentials, hyperbolic tangent potentials, and those with a sudden phase transition. In the end, we utilize the spectator scenario to explain the CMB power asymmetry, with a brief tachyonic fast-roll phase.

  1. Large Scale Anomalies of the Cosmic Microwave Background with Planck

    DEFF Research Database (Denmark)

    Frejsel, Anne Mette

    This thesis focuses on the large scale anomalies of the Cosmic Microwave Background (CMB) and their possible origins. The investigations consist of two main parts. The first part is on statistical tests of the CMB, and the consistency of both maps and power spectrum. We find that the Planck data...... is very consistent, while the WMAP 9 year release appears more contaminated by non-CMB residuals than the 7 year release. The second part is concerned with the anomalies of the CMB from two approaches. One is based on an extended inflationary model as the origin of one specific large scale anomaly, namely....... Here we find evidence that the Planck CMB maps contain residual radiation in the loop areas, which can be linked to some of the large scale CMB anomalies: the point-parity asymmetry, the alignment of quadrupole and octupole and the dipolemodulation....

  2. Teaching about Natural Background Radiation

    Science.gov (United States)

    Al-Azmi, Darwish; Karunakara, N.; Mustapha, Amidu O.

    2013-01-01

    Ambient gamma dose rates in air were measured at different locations (indoors and outdoors) to demonstrate the ubiquitous nature of natural background radiation in the environment and to show that levels vary from one location to another, depending on the underlying geology. The effect of a lead shield on a gamma radiation field was also…

  3. The music of the Big Bang the cosmic microwave background and the new cosmology

    CERN Document Server

    Balbi, Amedeo

    2008-01-01

    The cosmic microwave background radiation is the afterglow of the big bang: a tenuous signal, more than 13 billion years old, which carries the answers to many of the questions about the nature of our Universe. It was serendipitously discovered in 1964, and thoroughly investigated in the last four decades by a large number of experiments. Two Nobel Prizes in Physics have already been awarded for research on the cosmic background radiation: one in 1978 to Arno Penzias and Robert Wilson, who first discovered it, the other in 2006, to George Smoot and John Mather, for the results of the COBE satellite. Most cosmological information is encoded in the cosmic background radiation by acoustic oscillations in the dense plasma that filled the primordial Universe: a "music" of the big bang, which cosmologists have long been trying to reconstruct and analyze, in order to distinguish different cosmological models, much like one can distinguish different musical instruments by their timbre and overtones. Only lately, this...

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

    Science.gov (United States)

    Kostelecký, V Alan; Mewes, Matthew

    2007-07-06

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

  5. Spider casts its web on the cosmic microwave background

    Science.gov (United States)

    Banks, Michael

    2015-02-01

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

  6. Using the cosmic microwave background to discriminate among inflation models

    Energy Technology Data Exchange (ETDEWEB)

    Kinney, W.H.

    1997-12-23

    The upcoming satellite missions MAP and Planck will measure the spectrum of fluctuations in the Cosmic Microwave Background with unprecedented accuracy. I discuss the prospect of using these observations to distinguish among proposed models of inflationary cosmology.

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

    CERN Document Server

    Pearson, T J; Readhead, A C S; Shepherd, M C; Sievers, J L; Udomprasert, P S; Cartwright, J K; Farmer, A J; Padin, S; Myers, S T; Bond, J R; Contaldi, C R; Pen, U L; Prunet, S; Pogosyan, D; Carlstrom, J E; Kovács, J; Leitch, E M; Pryke, C L; Halverson, N W; Holzapfel, W L; Altamirano, P; Bronfman, L; Casassus, S; May, J; Joy, M

    2003-01-01

    Using the Cosmic Background Imager, a 13-element interferometer array operating in the 26-36 GHz frequency band, we have observed 40 sq deg of sky in three pairs of fields, each ~ 145 x 165 arcmin, 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 ~ 6 - 15 arcmin, corresponding to masses ~ (5 - 80)*10^{14} Msun 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 = 200 an...

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Tsumura, K.; Arai, T.; Matsumoto, T.; Matsuura, S.; Murata, K. [Department of Space Astronomy and Astrophysics, Institute of Space and Astronoutical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa 252-5210 (Japan); Battle, J.; Bock, J. [Jet Propulsion Laboratory (JPL), National Aeronautics and Space Administration (NASA), Pasadena, CA 91109 (United States); Brown, S.; Lykke, K.; Smith, A. [Optical Technology Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899 (United States); Cooray, A. [Center for Cosmology, University of California, Irvine, Irvine, CA 92697 (United States); Hristov, V.; Levenson, L. R.; Mason, P. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Keating, B.; Renbarger, T. [Department of Physics, University of California, San Diego, San Diego, CA 92093 (United States); Kim, M. G. [Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, D. H.; Nam, U. W. [Korea Astronomy and Space Science Institute (KASI), Daejeon 305-348 (Korea, Republic of); Sullivan, I., E-mail: tsumura@ir.isas.jaxa.jp [Department of Physics, The University of Washington, Seattle, WA 98195 (United States); 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.

  10. Electromagnetic radiation of superconducting cosmic strings

    Science.gov (United States)

    Rogozin, D. A.; Zadorozhna, L. V.

    2013-12-01

    Cosmic strings are relics of the early Universe which can be formed during the phase transitions of fields with spontaneously broken symmetry in the early Universe. Their existence finds support in modern superstrings theories, both in compactification models and in theories with extended additional dimensions. Strings can hold currents, effectively become electrically superconducting wires of astrophysical dimensions. Superconducting cosmic strings can serve as powerful sources of non-thermal radiation in wide energy range. Mechanisms of radiation are synchrotron, synchrotron self-Compton and inverse-Compton on CMB photons radiation of electrons accelerated by bow shock wave, created by magnetosphere of relativistically moving string in intergalactic medium (IGM). Expected fluxes of radiation from the shocked plasma around superconducting cosmic strings are calculated for strings with various tensions and for different cases of their location. Possibilities of strings detection by existing facilities are estimated.

  11. Cosmic Radiation Fields: Sources in the early Universe

    Science.gov (United States)

    Raue, Martin; Kneiske, Tanja; Horns, Dieter; Elsaesser, Dominik; Hauschildt, Peter

    The workshop "Cosmic Radiation Fields - Sources in the Early Universe" (CRF 2010) focuses on the connection between the extragalactic infrared background and sources in the early universe, in particular stars powered by dark matter burning (Dark Stars; DS). The workshop covers the following topics: the cosmic infrared background, formation of early stars, dark stars, effect of dark matter in the early universe, dark matter halos, primordial star formation rate, and reionization. Further information can be found on the conference webpage: http://www.desy.de/crf2010/. Organizing committee: Tanja Kneiske, Martin Raue, Dominik Elsaesser, Alexander Gewering-Peine, Peter Hausschildt, Dieter Horns, and Andreas Maurer.

  12. Ultra High Energy Comic Rays in the Cosmic Microwave Background

    CERN Document Server

    Hwang, W-Y Pauchy

    2011-01-01

    We consider the propagation of ultra high energy cosmic rays (UHECR), for energies greater than E > 10^{14} eV but less than E < 10^{26} eV, in the cosmic medium of the Cosmic Microwave Background (CMB). We find that the CMB plays a pivot role in this energy range. As example, the observed "knee(s)" and the "ankle" could be understood in reasonable terms. What we may observe at energy near 10^{25} eV (W^\\pm bursts or Z^0 bursts) is also briefly discussed.

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

    CERN Document Server

    Evoli, Carmelo; Mirizzi, Alessandro; Montanino, Daniele

    2016-01-01

    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 $\\tau$. Using the current measurement of $\\tau$ and the limit on the extra-radiation content $\\Delta N_{\\rm eff} $ 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 $g_{a\\gamma}$ times the magnetic field strength $B$ down to $g_{a\\gamma} B \\gtrsim 6 \\times 10^{-18} \\textrm{GeV}^{-1} \\textrm{nG} $ for ultralight ALPs.

  14. Detection of Cosmic Microwave Background Structure in a Second Field with the Cosmic Anisotropy Telescope

    CERN Document Server

    Baker, J C; Hobson, M P; Jones, M E; Kneissl, R; Lasenby, A N; O'Sullivan, C M M; Pooley, G G; Rocha, G; Saunders, R; Scott, P F; Waldram, E M; Baker, Joanne C.; Grainge, Keith; Jones, Michael E.; Pooley, Guy; Saunders, Richard

    1999-01-01

    We describe observations at frequencies near 15 GHz of the second 2x2 degree field imaged with the Cambridge Cosmic Anisotropy Telescope (CAT). After the removal of discrete radio sources, structure is detected in the images on characteristic scales of about half a degree, corresponding to spherical harmonic multipoles in the approximate range l= 330--680. A Bayesian analysis confirms that the signal arises predominantly from the cosmic microwave background (CMB) radiation for multipoles in the lower half of this range; the average broad-band power in a bin with centroid l=422 (theta = 51') is estimated to be Delta_T/T=2.1^{+0.4}_{-0.5} x 10^{-5}. For multipoles centred on l=615 (theta =35'), we find contamination from Galactic emission is significant, and constrain the CMB contribution to the measured power in this bin to be Delta_T/T <2.0 x 10^{-5} (1-sigma upper limit). These new results are consistent with the first detection made by CAT in a completely different area of sky. Together with data from ot...

  15. COBE Observations of the Cosmic Infrared Background

    CERN Document Server

    Wright, E L

    2004-01-01

    The Diffuse InfraRed Background Experiment on COBE measured the total infrared signal seen from space at a distance of 1 astronomical unit from the Sun. Using time variations as the Earth orbits the Sun, it is possible to remove most of the foreground signal produced by the interplanetary dust cloud [zodiacal light]. By correlating the DIRBE signal with the column density of atomic hydrogen measured using the 21 cm line, it is possible to remove most of the foreground signal produced by interstellar dust, although one must still be concerned by dust associated with H_2 (molecular gas) and H II (the warm ionized medium). DIRBE was not able to determine the CIRB in the 5-60 micron wavelength range, but did detect both a far infrared background and a near infrared background. The far infrared background has an integrated intensity of about 34 nW/m^2/sr, while the near infrared and optical extragalactic background has about 59 nW/m^2/sr. The Far InfraRed Absolute Spectrophotometer (FIRAS) on COBE has been used to...

  16. Cosmic radiation exposure and persistent cognitive dysfunction

    Science.gov (United States)

    Parihar, Vipan K.; Allen, Barrett D.; Caressi, Chongshan; Kwok, Stephanie; Chu, Esther; Tran, Katherine K.; Chmielewski, Nicole N.; Giedzinski, Erich; Acharya, Munjal M.; Britten, Richard A.; Baulch, Janet E.; Limoli, Charles L.

    2016-01-01

    The Mars mission will result in an inevitable exposure to cosmic radiation that has been shown to cause cognitive impairments in rodent models, and possibly in astronauts engaged in deep space travel. Of particular concern is the potential for cosmic radiation exposure to compromise critical decision making during normal operations or under emergency conditions in deep space. Rodents exposed to cosmic radiation exhibit persistent hippocampal and cortical based performance decrements using six independent behavioral tasks administered between separate cohorts 12 and 24 weeks after irradiation. Radiation-induced impairments in spatial, episodic and recognition memory were temporally coincident with deficits in executive function and reduced rates of fear extinction and elevated anxiety. Irradiation caused significant reductions in dendritic complexity, spine density and altered spine morphology along medial prefrontal cortical neurons known to mediate neurotransmission interrogated by our behavioral tasks. Cosmic radiation also disrupted synaptic integrity and increased neuroinflammation that persisted more than 6 months after exposure. Behavioral deficits for individual animals correlated significantly with reduced spine density and increased synaptic puncta, providing quantitative measures of risk for developing cognitive impairment. Our data provide additional evidence that deep space travel poses a real and unique threat to the integrity of neural circuits in the brain. PMID:27721383

  17. Cosmic radiation exposure and persistent cognitive dysfunction.

    Science.gov (United States)

    Parihar, Vipan K; Allen, Barrett D; Caressi, Chongshan; Kwok, Stephanie; Chu, Esther; Tran, Katherine K; Chmielewski, Nicole N; Giedzinski, Erich; Acharya, Munjal M; Britten, Richard A; Baulch, Janet E; Limoli, Charles L

    2016-10-10

    The Mars mission will result in an inevitable exposure to cosmic radiation that has been shown to cause cognitive impairments in rodent models, and possibly in astronauts engaged in deep space travel. Of particular concern is the potential for cosmic radiation exposure to compromise critical decision making during normal operations or under emergency conditions in deep space. Rodents exposed to cosmic radiation exhibit persistent hippocampal and cortical based performance decrements using six independent behavioral tasks administered between separate cohorts 12 and 24 weeks after irradiation. Radiation-induced impairments in spatial, episodic and recognition memory were temporally coincident with deficits in executive function and reduced rates of fear extinction and elevated anxiety. Irradiation caused significant reductions in dendritic complexity, spine density and altered spine morphology along medial prefrontal cortical neurons known to mediate neurotransmission interrogated by our behavioral tasks. Cosmic radiation also disrupted synaptic integrity and increased neuroinflammation that persisted more than 6 months after exposure. Behavioral deficits for individual animals correlated significantly with reduced spine density and increased synaptic puncta, providing quantitative measures of risk for developing cognitive impairment. Our data provide additional evidence that deep space travel poses a real and unique threat to the integrity of neural circuits in the brain.

  18. Probing the Universe's Tilt with the Cosmic Infrared Background Dipole

    CERN Document Server

    Fixsen, D J

    2011-01-01

    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 hypothesis is whether other cosmic dipoles produced by collapsed structures later than last scattering coincide with the CMB dipole. One background is the cosmic infrared background (CIB) whose absolute spectrum was measured to ~30% by the COBE satellite. Over the 100 to 500 um wavelength range its spectral energy distribution can provide a probe of its alignment with CMB. This is tested with the COBE FIRAS dataset which is available for such a measurement because of its low noise and frequency resolution 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...

  19. Does electromagnetic radiation accelerate galactic cosmic rays

    Science.gov (United States)

    Eichler, D.

    1977-01-01

    The 'reactor' theories of Tsytovich and collaborators (1973) of cosmic-ray acceleration by electromagnetic radiation are examined in the context of galactic cosmic rays. It is shown that any isotropic synchrotron or Compton reactors with reasonable astrophysical parameters can yield particles with a maximum relativistic factor of only about 10,000. If they are to produce particles with higher relativistic factors, the losses due to inverse Compton scattering of the electromagnetic radiation in them outweigh the acceleration, and this violates the assumptions of the theory. This is a critical restriction in the context of galactic cosmic rays, which have a power-law spectrum extending up to a relativistic factor of 1 million.

  20. Cosmic Infrared Background Fluctuations and Zodiacal Light

    CERN Document Server

    Arendt, Richard G; Moseley, S H; Mather, J

    2016-01-01

    We have 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 $\\sim2$ 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 ...

  1. Correlation between galactic HI and the cosmic microwave background

    Science.gov (United States)

    Land, Kate; Slosar, Anže

    2007-10-01

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

  2. Search for Antihelium in the Cosmic Radiation

    DEFF Research Database (Denmark)

    Streitmatter, R.E.; Barbier, L.M.; Christian, E.R.;

    1996-01-01

    The balloon-borne Isotope Matter-Antimatter Experiment (IMAX) was flown from Lynn Lake, Manitoba Canada on July 16-17, 1992. Sixteen hours of data were taken. Measurements of multiple dE/dX, rigidity, and time of flight were used to search for antihelium in the cosmic radiation. A report on the r...

  3. Higher Dimensional Radiation Collapse and Cosmic Censorship

    CERN Document Server

    Ghosh, S G

    2000-01-01

    We study the occurrence of naked singularities in the spherically symmetric collapse of radiation shells in a higher dimensional spacetime. The necessary conditions for the formation of a naked singularity or a black hole are obtained. The naked singularities are found to be strong in the Tipler's sense and thus violating cosmic censorship conjecture.

  4. Cosmology with cosmic microwave background anisotropy

    Indian Academy of Sciences (India)

    Tarun Sourdeep

    2006-10-01

    Measurements of CMB anisotropy and, more recently, polarization have played a very important role in allowing precise determination of various parameters of the `standard' cosmological model. The expectation of the paradigm of inflation and the generic prediction of the simplest realization of inflationary scenario in the early Universe have also been established - `acausally' correlated initial perturbations in a flat, statistically isotropic Universe, adiabatic nature of primordial density perturbations. Direct evidence for gravitational instability mechanism for structure formation from primordial perturbations has been established. In the next decade, future experiments promise to strengthen these deductions and uncover the remaining crucial signature of inflation - the primordial gravitational wave background.

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

    Science.gov (United States)

    Mather, John

    2015-01-01

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

  6. Large Angular Scale Anisotropy in Cosmic Microwave Background Induced by Cosmic Strings

    Energy Technology Data Exchange (ETDEWEB)

    Allen, B.; Caldwell, R.R.; Shellard, E.P.; Stebbins, A.; Veeraraghavan, S. [Department of Physics, University of Wisconsin---Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201 (United States)]|[University of Cambridge, Department of Applied Mathematics and Theoretical Physics, Silver Street, Cambridge CB3 9EW (United Kingdom)]|[NASA/Fermilab Astrophysics Center, P.O. Box 500, Batavia, Illinois 60510 (United States)]|[NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)

    1996-10-01

    We simulate the anisotropy in the cosmic microwave background (CMB) induced by cosmic strings. By numerically evolving a network of cosmic strings we generate full-sky CMB temperature anisotropy maps. Based on 192 maps, we compute the anisotropy power spectrum for multipole moments l{le}20. By comparing with the observed temperature anisotropy, we set the normalization for the cosmic string mass per unit length {mu}, obtaining {ital G}{mu}/{ital c}{sup 2}=1.05{sub {minus}0.20}{sup +0.35}{times}10{sup {minus}6}, which is consistent with all other observational constraints on cosmic strings. We demonstrate that the anisotropy pattern is consistent with a Gaussian random field on large angular scales. {copyright} {ital 1996 The American Physical Society.}

  7. Alternative application for the radiation background in the development of the atlas database of atmospheric radiation

    CERN Document Server

    De la Hoz, Ivan Arturo Morales

    2014-01-01

    Nowadays radiation is one of the variables to be considered in the environmental forecasting and it is meaningful in the increase of global warming, together greenhouse effect. The radiation considered by the meteorological organizations depends on the World Radiometric Reference (WRR), the World Standard Group (WSG), addressed by the World Meteorological Organization (WMO). This work is based on the cosmic microwave background, as a variable to be estimated in order to get information about the incident radiation in the Earth's atmosphere, as a valuable and meaningful contribution in the building of the radiation atlas by the (UPME) and (IDEAM). Due to the fact that the variables considered are ultraviolet and infrared radiation, ozone column, direct radiation and diffuse radiation, the last two get the global radiation, and are the only ones to be evaluated by the national meteorological organizations in the country. The study of the cosmic background radiation as a research project will provide data which ...

  8. The Cosmic Microwave Background Spectrum and a Determination of Fractal Space Dimensionality

    CERN Document Server

    Caruso, Francisco

    2009-01-01

    The possibility to constrain fractal space dimensionality form Astrophysics and other areas is briefly reviewed. Using data from FIRAS instrument aboard COBE satellite and assuming space dimensionality to be $3 + \\epsilon$, we calculate $\\epsilon = - (0.957 \\pm 0.006) \\times 10^{-5}$ and an absolute temperature 2.726 $\\pm$ 0.00003 K by fitting the cosmic microwave background radiation spectrum to Planck's radiation distribution.

  9. Detection of Polarization in the Cosmic Microwave Background using DASI

    CERN Document Server

    Kovács, J M; Pryke, C L; Carlstrom, J E; Halverson, N W; Holzapfel, W L

    2002-01-01

    We report the detection of polarized anisotropy in the Cosmic Microwave Background radiation with the Degree Angular Scale Interferometer (DASI), located at the Amundsen-Scott South Pole research station. Observations in all four Stokes parameters were obtained within two 3.4 FWHM fields separated by one hour in Right Ascension. The fields were selected from the subset of fields observed with DASI in 2000 in which no point sources were detected and are located in regions of low Galactic synchrotron and dust emission. The temperature angular power spectrum is consistent with previous measurements and its measured frequency spectral index is -0.01 (-0.16 -- 0.14 at 68% confidence), where 0 corresponds to a 2.73 K Planck spectrum. The power spectrum of the detected polarization is consistent with theoretical predictions based on the interpretation of CMB anisotropy as arising from primordial scalar adiabatic fluctuations. Specifically, E-mode polarization is detected at high confidence (4.9 sigma). Assuming a sh...

  10. DASI Three-Year Cosmic Microwave Background Polarization Results

    CERN Document Server

    Leitch, E M; Halverson, N W; Carlstrom, J E; Pryke, C L; Smith, M W E; Leitch, Erik M.

    2004-01-01

    We present the analysis of the complete 3-year data set obtained with the Degree Angular Scale Interferometer (DASI) polarization experiment, operating from the Amundsen-Scott South Pole research station. Additional data obtained at the end of the 2002 Austral winter and throughout the 2003 season were added to the data from which the first detection of polarization of the cosmic microwave background radiation was reported. The analysis of the combined data supports, with increased statistical power, all of the conclusions drawn from the initial data set. In particular, the detection of E-mode polarization is increased to 6.3 sigma confidence level, TE cross-polarization is detected at 2.9 sigma, and B-mode polarization is consistent with zero, with an upper limit well below the level of the detected E-mode polarization. The results are in excellent agreement with the predictions of the cosmological model that has emerged from CMB temperature measurements. The analysis also demonstrates that contamination of ...

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

    Science.gov (United States)

    Silk, Joseph

    1990-01-01

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

  12. Academic Training: The cosmic microwave background - Lecture series

    CERN Multimedia

    Françoise Benz

    2004-01-01

    ACADEMIC TRAINING LECTURE REGULAR PROGRAMME 14, 15, 16, 17 and 18 June From 11:00 hrs to 12:00 hrs - Main Auditorium bldg. 500 The cosmic microwave background M. Zaldarriaga / Harvard University, USA ENSEIGNEMENT ACADEMIQUE ACADEMIC TRAINING Françoise Benz 73127 academic.training@cern.ch

  13. Determining cosmic microwave background structure from its peak distribution

    CERN Document Server

    Kashlinsky, A; Atrio-Barandela, F

    2001-01-01

    We present a new method for time-efficient and accurate extraction of the power spectrum from future cosmic microwave background (CMB) maps based on properties of peaks and troughs of the Gaussian CMB sky. We construct a statistic describing their angular clustering - analogously to galaxies, the 2-point angular correlation function, $\\xi_\

  14. Real-Time Active Cosmic Neutron Background Reduction Methods

    Energy Technology Data Exchange (ETDEWEB)

    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

  15. Quantum dynamics of scalar bosons in a cosmic string background

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Luis B. [Universidade Federal do Maranhao, Departamento de Fisica, Sao Luis, MA (Brazil)

    2015-06-15

    The quantum dynamics of scalar bosons embedded in the background of a cosmic string is considered. In this work, scalar bosons are described by the Duffin-Kemmer-Petiau (DKP) formalism. In particular, the effects of this topological defect in the equation of motion, energy spectrum, and DKP spinor are analyzed and discussed in detail. The exact solutions for the DKP oscillator in this background are presented in closed form. (orig.)

  16. Inhomogeneous Reionization and the Polarization of the Cosmic Microwave Background.

    Science.gov (United States)

    Weller

    1999-12-10

    In a universe with inhomogeneous reionization, the ionized patches create a second-order signal in the cosmic microwave background polarization anisotropy. This signal originates in the coupling of the free-electron fluctuation to the quadruple moment of the temperature anisotropy. We examine the contribution from a simple inhomogeneous reionization model and find that the signal from such a process is below the detectable limits of the Planck Surveyor mission. However, the signal is above the fundamental uncertainty limit from cosmic variance, so that a future detection with a high-accuracy experiment on subarcminute scales is possible.

  17. Giant Rings in the Cosmic Microwave Background Sky

    Science.gov (United States)

    Kovetz, Ely D.; Ben-David, Assaf; Itzhaki, Nissan

    2010-11-01

    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 3σ level and the alignment with the bulk flow at 2.5σ. We argue that a cosmic defect seeded by a pre-inflationary particle could explain the giant rings, the large bulk flow, and their alignment.

  18. Change of Primary Cosmic Radiation Nuclear Conposition in the Energy Range $10^{15} - 10^{17}$ eV as a Result of the Interaction with the Interstellar Cold Background of Light Particles

    CERN Document Server

    Barnaveli, T T; Khaldeeva, I V

    2003-01-01

    In this paper the updated arguments in favor of a simple model, explaining from the united positions all peculiarities of the Extensive Air Shower (EAS) hadron E_h(E_0) (and muon E_mu(E_0)) component energy fluxes dependence on the primary particle energy E_0 in the primary energy region 10^{15} - 10^{17} eV are represented. These peculiarities have shapes of consequent distinct deeps of a widths dE_h/E_h of the order of 0.2 and of relative amplitudes dL/L of the order of {0.1 - 1.0}, and are difficult to be explained via known astrophysical mechanisms of particle generation and acceleration. In the basis of the model lies the destruction of the Primary Cosmic Radiation (PCR) nuclei on some monochromatic background of interstellar space, consisting of the light particles of the mass in the area of 36 eV (maybe the component of a dark matter). The destruction thresholds of PCR different nuclear components correspond to the peculiarities of E_h(E_0). In this work the results of the recent treatment of large sta...

  19. Background radiation measurement with water Cherenkov detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bertou, X., E-mail: bertou@cab.cnea.gov.a [CONICET/CNEA, Centro Atomico Bariloche (Argentina); Observatorio Pierre Auger, Av. San Martin Norte 304, 5613 Malarguee (Argentina)

    2011-05-21

    Water Cherenkov Detectors have the nice property of being mostly calorimeters for cosmic ray induced electrons and photons, while providing a clear signal for muons. At large energy deposited in the detector, they observe small extended air showers. This makes them interesting detectors to study the background of cosmic ray secondaries. Using low threshold scaler counters, one can follow the flux of cosmic rays on top of the atmosphere, and/or study atmospheric effects on the cosmic ray shower development. In this paper, background data from the Pierre Auger Observatory are presented. These data are searched for short time-scale variation (one second scale, as expected from Gamma Ray Bursts), and larger time-scale variations, showing modulation effects due to Solar activity (Forbush decreases). Rapid changes in the background flux are also observed during the crossing of storms over the 3000 km{sup 2} of the ground array.

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

    Science.gov (United States)

    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.

  1. International Cooperation of the Cosmic Infrared Background Experiment

    Science.gov (United States)

    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.

  2. Cosmic microwave background anisotropies seeded by incoherent sources

    CERN Document Server

    Riazuelo, A; Riazuelo, Alain; Deruelle, Nathalie

    2000-01-01

    The cosmic microwave background anisotropies produced by active seeds, such as topological defects, have been computed recently for a variety of models by a number of authors. In this paper we show how the generic features of the anisotropies caused by active, incoherent, seeds (that is the absence of acoustic peaks at small scales) can be obtained semi-analytically, without entering into the model dependent details of their formation, structure and evolution.

  3. Can decaying particle explain cosmic infrared background excess?

    Directory of Open Access Journals (Sweden)

    Kazunori Kohri

    2017-09-01

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

  4. Can decaying particle explain cosmic infrared background excess?

    Science.gov (United States)

    Kohri, Kazunori; Moroi, Takeo; Nakayama, Kazunori

    2017-09-01

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

  5. Primary and Secondary Anisotropies of Cosmic Microwave Background

    Science.gov (United States)

    Seljak, Uros

    2002-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lima, J.A.S. [Departamento de Astronomia, Universidade de São Paulo, 55080-900, São Paulo, SP (Brazil); Graef, L.L. [Instituto de Física, Universidade de São Paulo, Rua do Matão travessa R, 05508-090, São Paulo, SP (Brazil); Pavón, D. [Departamento de Física, Universidad Autónoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Basilakos, Spyros, E-mail: jas.lima@iag.usp.br, E-mail: leilagraef@usp.br, E-mail: diego.pavon@uab.es, E-mail: svasil@academyofathens.gr [Academy of Athens, Research Center for Astronomy and Applied Mathematics, Soranou Efesiou 4, 11527, Athens (Greece)

    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.

  7. Cosmic radiation algorithm utilizing flight time tables

    Energy Technology Data Exchange (ETDEWEB)

    Katja Kojo, M.Sc.; Mika Helminen, M.Sc.; Anssi Auvinen, M.D.Ph.D. [STUK - Radiation and Nuclear Safety Authority, Helsinki (Finland); Katja Kojo, M.Sc.; Anssi Auvinen, M.D.Ph.D. [Tampere Univ., School of Public Health (Finland); Gerhard Leuthold, D.Sc. [GSF - Research Center, Institute of Radiation Protection, Neuherberg (Germany)

    2006-07-01

    Cosmic radiation is considerably higher on cruising altitudes used in aviation than at ground level. Exposure to cosmic radiation may increase cancer risk among pilots and cabin crew. The International Commission on Radiation Protection (ICRP) has recommended that air crew should be classified as radiation workers. Quantification of cosmic radiation doses is necessary for assessment of potential health effects of such occupational exposure. For Finnair cabin crew (cabin attendants and stewards), flight history is not available for years prior to 1991 and therefore, other sources of information on number and type of flights have to be used. The lack of systematically recorded information is a problem for dose estimation for many other flight companies personnel as well. Several cosmic radiation dose estimations for cabin crew have been performed using different methods (e.g. 2-5), but they have suffered from various shortcomings. Retrospective exposure estimation is not possible with personal portable dosimeters. Methods that employ survey data for occupational dose assessment are prone to non-differential measurement error i.e. the cabin attendants do not remember correctly the number of past flights. Assessment procedures that utilize surrogate measurement methods i.e. the duration of employment, lack precision. The aim of the present study was to develop an assessment method for individual occupational exposure to cosmic radiation based on flight time tables. Our method provides an assessment method that does not require survey data or systematic recording of flight history, and it is rather quick, inexpensive, and possible to carry out in all other flight companies whose past time tables for the past periods exist. Dose assessment methods that employ survey data are prone to random error i.e. the cabin attendants do not remember correctly the number or types of routes that they have flown during the past. Our method avoids this since survey data are not needed

  8. Cosmic radiation exposure at aircraft crew workplaces

    Energy Technology Data Exchange (ETDEWEB)

    Latocha, M.; Beck, P.; Rollet, S. [ARC Seibersdorf Research, Seibersdorf (Austria); Latocha, M. [Institute of Nuclear Physics Polish Academy of Sciences, Krakow (Poland)

    2006-07-01

    E.U.R.A.D.O.S. working group W.G.5. on air crew dosimetry coordinated research of some 24 international institutes to exchange experimental data and results of calculations of the radiation exposure in aircraft altitudes due to cosmic radiation. The purpose was to provide a data-set for all European Union Member States for the assessment of individual doses, the validity of different approaches, and to provide an input to technical recommendations by the Article 31 group of experts and the European Commission. The results of this work have been recently published and are available for the international community. The radiation protection quantity of interest is effective dose, E (ISO), but the comparison of measurement results and the results of calculations, is done in terms of the operational quantity ambient dose equivalent, H{sup *}(10). This paper gives an overview of the E.U.R.A.D.O.S. Aircraft Crew In-Flight Database which was implemented under the responsibility of A.R.C. Seibersdorf research. It discusses calculation models for air crew dose assessment comparing them with measurements contained in this database. Further it presents current developments using updated information of galactic cosmic radiation proton spectra and new results of the recently finalized European research project D.O.S.M.A.X. on dosimetry of aircraft crew at solar maximum. (authors)

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

    Science.gov (United States)

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

    2014-04-04

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

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

    CERN Document Server

    Ade, P A R; Anthony, A E; Arnold, K; 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; Jeune, M Le; Lee, A T; 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; 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

    2013-01-01

    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 (CIB) maps from the Herschel satellite. From the cross-spectra, we obtain evidence for gravitational lensing of the CMB polarization at a statistical significance of 4.0$\\sigma$ and evidence for the presence of a lensing $B$-mode signal at a significance of 2.3$\\sigma$. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Gaier, T.; Schuster, J.; Lubin, P. (University of California, Santa Barbara, CA 93106 (USA))

    1990-01-15

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

  12. Wavelet-Bayesian inference of cosmic strings embedded in the cosmic microwave background

    CERN Document Server

    McEwen, J D; Peiris, H V; Wiaux, Y; Ringeval, C; Bouchet, F R

    2016-01-01

    Cosmic strings are a well-motivated extension to the standard cosmological model and could induce a subdominant component in the anisotropies of the cosmic microwave background (CMB), in addition to the standard inflationary component. The detection of strings, while observationally challenging, would provide a direct probe of physics at very high energy scales. We develop a new framework for cosmic string inference, constructing a Bayesian analysis in wavelet space where the string-induced CMB component has distinct statistical properties to the standard inflationary component. Our wavelet-Bayesian framework provides a principled approach to compute the posterior distribution of the string tension $G\\mu$ and the Bayesian evidence ratio comparing the string model to the standard inflationary model. Furthermore, we present a technique to recover an estimate of any string-induced CMB map embedded in observational data. Using Planck-like simulations we demonstrate the application of our framework and evaluate it...

  13. Multiple Cosmic Collisions and the Microwave Background Power Spectrum

    CERN Document Server

    Kozaczuk, Jonathan

    2012-01-01

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

  14. Anencephalus, drinking water, geomagnetism and cosmic radiation.

    Science.gov (United States)

    Archer, V E

    1979-01-01

    The mortality rates from anencephalus from 1950-1969 in Canadian cities are shown to be strongly correlated with city growth rate and with horizontal geomagnetic flux, which is directly related to the intensity of cosmic radiation. They are also shown to have some association with the magnesium content of drinking water. Prior work with these data which showed associations with magnesium in drinking water, mean income, latitude and longitude was found to be inadequate because it dismissed the observed geographic associations as having little biological meaning, and because the important variables of geomagnetism and city growth rate were overlooked.

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

    Science.gov (United States)

    Baccigalupi, Carlo

    1999-06-01

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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2017-07-01

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

  18. Magneto-optic effects of the Cosmic Microwave Background

    CERN Document Server

    Ejlli, Damian

    2016-01-01

    Generation of magneto-optic effects by the cosmic microwave background (CMB) in the presence of cosmic magnetic fields is studied. Four mechanisms which generate polarization of the CMB such as the Cotton-Mouton effect, the vacuum polarization in external magnetic field, the photon-pseudoscalar mixing in external magnetic field and the Faraday effect are studied. Considering the CMB linearly polarized at decoupling time due to Thomson scattering, it is shown that second order effects in the magnetic field amplitude such as the Cotton-Mouton effect in plasma and the vacuum polarization (Euler-Heisenberg term) in cosmic magnetic field, would generate elliptic polarization of the CMB at post decoupling time depending on the photon frequency and magnetic field strength. The Cotton-Mouton effect in plasma turns out to be the dominant effect in the generation of CMB elliptic polarization in the low frequency part while the vacuum polarization in magnetic field is the dominant process in the high frequency part. The...

  19. Probing the Universe's Tilt with the Cosmic Infrared Background Dipole

    Science.gov (United States)

    Fixsen, D. J.; Kashlinsky, A.

    2011-06-01

    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 ~30% by the COBE satellite. Over the 100-500 μm 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 ~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.

  20. Prospectives on Direct Detection of the Cosmic Neutrino Background

    Science.gov (United States)

    Li, Yu-Feng

    2017-09-01

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

  1. Cosmic microwave background anisotropies with mixed isocurvature perturbations.

    Science.gov (United States)

    Trotta, R; Riazuelo, A; Durrer, R

    2001-12-01

    In the light of the recent high quality data of the cosmic microwave background anisotropies, several estimations of cosmological parameters have been published. We study to what extent these estimations depend on assumptions about the initial conditions of the cosmological perturbations, which are usually supposed to be adiabatic. We show that, for more generic initial conditions, not only the best fit values are very different but the allowed parameter range enlarges dramatically. This raises the question which cosmological information (matter content of the Universe vs physics of inflation) can be reliably extracted from these data.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-01

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

  3. The cosmic infrared background resolved by Spitzer - Contributions of mid-infrared galaxies to the far-infrared background

    NARCIS (Netherlands)

    Dole, H; Lagache, G; Puget, JL; Caputi, KI; Fernandez-Conde, N; Le Floc'h, E; Papovich, C; Perez-Gonzalez, PG; Rieke, GH; Blaylock, M

    Aims. We quantify the contributions of 24 mu m galaxies to the Far-Infrared ( FIR) Background at 70 and 160 mu m. We provide new estimates of the Cosmic Infrared Background ( CIB), and compare it with the Cosmic Optical Background ( COB). Methods. Using Spitzer data at 24, 70 and 160 mu m in three

  4. Cosmic ray composition measurements and cosmic ray background free gamma-ray observations with Cherenkov telescopes

    CERN Document Server

    Neronov, A; Vovk, Ie; Mirzoyan, R

    2016-01-01

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

  5. What Can the Cosmic Microwave Background Tell Us About the Outer Solar System?

    CERN Document Server

    Babich, Daniel; Steinhardt, Charles

    2007-01-01

    We discuss two new observational techniques that use observations of the Cosmic Microwave Background (CMB) to place constraints upon the mass, distance, and size distribution of small objects in the Kuiper Belt and inner Oort Cloud, collectively known as Trans-Neptunian Objects (TNOs). The first new technique considers the spectral distortion of the isotropic, or monopole, CMB by TNOs that have been heated by solar radiation to temperatures above that of the CMB. We apply this technique to the spectral measurements of the CMB by the Far Infrared Absolute Spectrophotometer (FIRAS) on the Cosmic Background Explorer (COBE). The second technique utilizes the change in amplitude of the TNO signal due to the orbital motion of the observer to separate the TNO signal from the invariant extra-galactic CMB and construct a map of the mass distribution in the outer Solar System. We estimate the ability of future CMB experiments to create such a map.

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

    Science.gov (United States)

    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).

  7. Academic Training: The cosmic microwave background - Lecture series

    CERN Multimedia

    Françoise Benz

    2004-01-01

    ACADEMIC TRAINING LECTURE REGULAR PROGRAMME 14, 15, 16, 17 and 18 June From 11:00 hrs to 12:00 hrs - Main Auditorium bldg. 500 The cosmic microwave background M. Zaldarriaga / Harvard University, USA The Cosmic Microwave Background has become an indispensable tool for cosmology. The measurement of its frequency spectrum firmly established the Hot Big Bang model of the Universe. Measurements of anisotropies in its temperature and its degree of polarization provide the earliest snapshot we have of the universe, giving us information about its state at the epoch of hydrogen recombination approximately 300,000 after the Big Bang. The anisotropies can be used to constrain many of the parameters in the cosmological model, such as the mean density of baryons and dark matter as well as the curvature of the Universe. In this lectures I will review the physics of the temperature and polarization anisotropies. I will discuss the mechanisms that lead to the anisotropies and how cosmological parameters can be inferr...

  8. Cosmic backgrounds of relic gravitons and their absolute normalization

    Science.gov (United States)

    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.

  9. Radiative feedback and cosmic molecular gas: numerical method

    Science.gov (United States)

    Petkova, Margarita; Maio, Umberto

    2012-06-01

    We present the results from self-consistent numerical simulations of cosmic structure formation with a multifrequency radiative transfer scheme and non-equilibrium molecular chemistry of 13 primordial species (e-, H, H+, H-, He, He+, He++, H2, H?, D, D+, HD and HeH+), performed using the simulation code GADGET. We describe our implementation and we show tests for ionized sphere expansion in a static and dynamic density field around a central radiative source, and for cosmological abundance evolution coupled with the cosmic microwave background radiation. As a demonstrative application of radiative feedback on molecular gas, we also run cosmological simulations of early structure formation in a ˜1-Mpc sized box. Our tests agree well with analytical and numerical expectations. Consistent with other works, we find that ionization fronts from central sources can boost H2 fractions in shock-compressed gas. The tight dependence on H2 also leads to a corresponding boost of HD fractions. We see a strong lowering of the typical molecular abundances up to several orders of magnitude, which partially hinders further gas collapse of pristine neutral gas. This clearly suggests the need for reionized gas or metal cooling in the formation of the following generation of structures.

  10. Cosmic Shear of the Microwave Background: The Curl Diagnostic

    CERN Document Server

    Cooray, A R; Caldwell, R R; Cooray, Asantha; Kamionkowski, Marc; Caldwell, Robert R.

    2005-01-01

    Weak-lensing distortions of the cosmic-microwave-background (CMB) temperature and polarization patterns can reveal important clues to the intervening large-scale structure. The effect of lensing is to deflect the primary temperature and polarization signal to slightly different locations on the sky. Deflections due to density fluctuations, gradient-type for the gradient of the projected gravitational potential, give a direct measure of the mass distribution. Curl-type deflections can be induced by, for example, a primordial background of gravitational waves from inflation or by second-order effects related to lensing by density perturbations. Whereas gradient-type deflections are expected to dominate, we show that curl-type deflections can provide a useful test of systematics and serve to indicate the presence of confusing secondary and foreground non-Gaussian signals.

  11. Charting the New Frontier of the Cosmic Microwave Background Polarization

    CERN Document Server

    Bouchet, F R; Camus, P; Désert, F X; Piat, M; Ponthieu, N; Camus, Ph.

    2005-01-01

    The anisotropies of the cosmic microwave background are a gold mine for cosmology and fundamental physics. ESA's Planck satellite should soon extract all information from the temperature vein but will be limited concerning the measurement of the degree of polarization of the anisotropies. This polarization information allows new independent tests of the standard cosmological paradigm, improves knowledge of cosmological parameters and last but not least is the best window available for constraining the physics of the very early universe, particularly the expected background of primordial gravitational waves. But exploiting this vein will be a challenge, since the sensitivity required is {\\em at least} 10 times better than what Planck might achieve at best, with the necessary matching level of control of all systematics effects, both instrumental and astrophysical (foregrounds). We here recall the cosmological context and the case for CMB polarization studies. We also briefly introduce the SAMPAN project, a des...

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

    Science.gov (United States)

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

    2017-07-01

    Secret contact interactions among eV sterile neutrinos, mediated by a massive gauge boson X (with MX ll MW), and characterized by a gauge coupling gX, have been proposed as a mean to reconcile cosmological observations and short-baseline laboratory anomalies. We constrain this scenario using the latest Planck data on Cosmic Microwave Background anisotropies, and measurements of baryon acoustic oscillations (BAO). We consistently include the effect of secret interactions on cosmological perturbations, namely the increased density and pressure fluctuations in the neutrino fluid, and still find a severe tension between the secret interaction framework and cosmology. In fact, taking into account neutrino scattering via secret interactions, we derive our own mass bound on sterile neutrinos and find (at 95 % CL) ms relatively large coupling gX~ 10-1, previously indicated as a possible solution to the small scale dark matter problem.

  13. Cosmic backgrounds of relic gravitons and their absolute normalization

    CERN Document Server

    Giovannini, Massimo

    2014-01-01

    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 of 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-frequencies...

  14. Cold+hot dark matter and the cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

    Dodelson, S. [NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States); Gates, E. [Department of Astronomy & Astrophysics, Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637-1433 (United States)]|[NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States); Stebbins, A. [NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States)

    1996-08-01

    We examine the cosmic microwave background power spectrum for adiabatic models with a massive neutrino component. We present the results of a detailed numerical evolution of cold+hot dark matter (CHDM) models and compare these results with the standard cold dark matter (CDM) spectrum. The difference is of order 5{percent}{endash}10{percent} for 400{lt}{ital l}{lt}1000 for currently popular CHDM models. Using semi-analytic approximations, we also discuss the relevant physics involved. Finally, we remark on the ability of future experiments to differentiate between these models. An all-sky experiment with a beam size smaller than 30{prime} can distinguish between CHDM and CDM if other cosmological parameters are known. Even allowing other parameters to vary, it may be possible to distinguish CDM from CHDM. {copyright} {ital 1996 The American Astronomical Society.}

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

    Energy Technology Data Exchange (ETDEWEB)

    Dragovan, M. (Joseph Henry Laboratory, Princeton University, Princeton, NJ 08544 (USA)); Platt, S.R.; Pernic, R.J. (The University of Chicago, Yerkes Observatory, Williams Bay, WI 531191 (USA)); Stark, A.A. (AT T Bell Laboratories, Holmdel, NJ 07733 (USA))

    1990-01-15

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

  16. Interpretation of spectral paradox of cosmic X-ray background

    Institute of Scientific and Technical Information of China (English)

    李志青; 周又元

    1997-01-01

    The integrated spectrum of discrete X-ray sources (mainly the active galactic nuclei, AGN) is inconsistent with the observed spectrum of cosmic X-ray background (CXB), and it is so called CXB spectral paradox. The medium X-ray spectra of 68 AGNs are adopted, the evolution function of X-ray spectral indices is analyzed statistically, the fraction of CXB is calculated due to AGNs X-ray emission, which shows that almost 100% CXB comes from AGNs X-ray emission. Especially, the integrated spectrum in 2-10 keV is consistent with the observed spectrum of CXB. The spectral paradox of CXB can be interpreted by this result.

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

    CERN Document Server

    Flender, Samuel

    2013-01-01

    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 6.5 sigma. 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 ~1 sigma, 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.

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

    Science.gov (United States)

    Kelsall, Thomas

    2010-01-01

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

  19. Systematic errors in cosmic microwave background polarization measurements

    CERN Document Server

    O'Dea, D; Johnson, B R; Dea, Daniel O'; Challinor, Anthony

    2006-01-01

    We investigate the impact of instrumental systematic errors on the potential of cosmic microwave background polarization experiments targeting primordial B-modes. To do so, we introduce spin-weighted Muller matrix-valued fields describing the linear response of the imperfect optical system and receiver, and give a careful discussion of the behaviour of the induced systematic effects under rotation of the instrument. We give the correspondence between the matrix components and known optical and receiver imperfections, and compare the likely performance of pseudo-correlation receivers and those that modulate the polarization with a half-wave plate. The latter is shown to have the significant advantage of not coupling the total intensity into polarization for perfect optics, but potential effects like optical distortions that may be introduced by the quasi-optical wave plate warrant further investigation. A fast method for tolerancing time-invariant systematic effects is presented, which propagates errors throug...

  20. Accelerating Cosmic Microwave Background map-making procedure through preconditioning

    CERN Document Server

    Szydlarski, Mikolaj; Stompor, Radek

    2014-01-01

    Estimation of the sky signal from sequences of time ordered data is one of the key steps in Cosmic Microwave Background (CMB) data analysis, commonly referred to as the map-making problem. Some of the most popular and general methods proposed for this problem involve solving generalised least squares (GLS) equations with non-diagonal noise weights given by a block-diagonal matrix with Toeplitz blocks. In this work we study new map-making solvers potentially suitable for applications to the largest anticipated data sets. They are based on iterative conjugate gradient (CG) approaches enhanced with novel, parallel, two-level preconditioners. We apply the proposed solvers to examples of simulated non-polarised and polarised CMB observations, and a set of idealised scanning strategies with sky coverage ranging from nearly a full sky down to small sky patches. We discuss in detail their implementation for massively parallel computational platforms and their performance for a broad range of parameters characterising...

  1. Phase Correlations in Cosmic Microwave Background Temperature Maps

    CERN Document Server

    Coles, P; Earl, J; Wright, D; Coles, Peter; Dineen, Patrick; Earl, John; Wright, Dean

    2003-01-01

    We study the statistical properties of spherical harmonic modes of temperature maps of the cosmic microwave background. Unlike other studies, which focus mainly on properties of the amplitudes of these modes, we look instead at their phases. In particular, we present a simple measure of phase correlation that can be diagnostic of departures from the standard assumption that primordial density fluctuations constitute a statistically homogeneous and isotropic Gaussian random field, which should possess phases that are uniformly random on the unit circle. The method we discuss checks for the uniformity of the distribution of phase angles using a non-parametric descriptor based on the use order statistics, which is known as Kuiper's statistic. The particular advantage of the method we present is that, when coupled to the judicious use of Monte Carlo simulations, it can deliver very interesting results from small data samples. In particular, it is useful for studying the properties of spherical harmonics at low l ...

  2. Cosmic microwave background science at commercial airline altitudes

    Science.gov (United States)

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

    2017-07-01

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

  3. Cosmic Microwave Background Science at Commercial Airline Altitudes

    CERN Document Server

    Feeney, Stephen M; Peiris, Hiranya V; Verde, Licia; Errard, Josquin

    2016-01-01

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

  4. Extracting cosmic microwave background polarisation from satellite astrophysical maps

    CERN Document Server

    Baccigalupi, C; De Zotti, G; Smoot, G F; Burigana, C; Maino, D; Bedini, L; Salerno, E

    2002-01-01

    We present the application of the Fast Independent Component Analysis technique for blind component separation to polarised astrophysical emission. We study how the Cosmic Microwave Background (CMB) polarised signal, consisting of $E$ and $B$ modes, can be extracted from maps affected by substantial contamination from diffuse Galactic foregrounds and instrumental noise. We perform the analysis of all sky maps simulated accordingly to the nominal performances of the Low Frequency Instrument (LFI) aboard the Planck satellite; the sky signal is modeled as a superposition of CMB, generated by a Gaussian, nearly scale invariant cosmological perturbation spectrum, and the existing simulated polarisation templates of Galactic synchrotron. Our results indicate that the angular power spectrum of CMB $E$ modes can be recovered on all scales up to $\\ell\\simeq 1000$, corresponding to the fourth acoustic oscillation, while $B$ modes can be detected, up to their turnover at $\\ell\\simeq 100$ if cosmological tensor amplitude...

  5. Searching for Faraday rotation in cosmic microwave background polarization

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Granett, Benjamin R.

    2010-10-01

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

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

    Science.gov (United States)

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

    2010-07-01

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

  9. A Polarization Sensitive Bolometric Detector for Observations of the Cosmic Microwave Background

    CERN Document Server

    Jones, W C; Bock, J J; Lange, A E

    2002-01-01

    We have developed a bolometric detector that is intrinsically sensitive to linear polarization which is optimized for making measurements of the polarization of the cosmic microwave background radiation. The receiver consists of a pair of co-located silicon nitride micromesh absorbers which couple anisotropically to linearly polarized radiation through a corrugated waveguide structure. This system allows simultaneous background limited measurements of the Stokes I and Q parameters over ~ 30% bandwidths at frequencies from ~ 60 to 600 GHz. Since both linear polarizations traverse identical optical paths from the sky to the point of detection, the susceptibility to systematic effects is minimized. The amount of uncorrelated noise between the two polarization senses is limited to the quantum limit of thermal and photon shot noise, while drifts in the relative responsivity to orthogonal polarizations are limited to the effect of non-uniformity in the thin film deposition of the leads and the intrinsic thermistor ...

  10. Circular dichroism, magnetic knots and the spectropolarimetry of the Cosmic Microwave Background

    CERN Document Server

    Giovannini, Massimo

    2010-01-01

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

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

    Science.gov (United States)

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

    2017-01-01

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

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

    CERN Document Server

    Aguirre, A N; Aguirre, Anthony; Haiman, Zoltan

    1999-01-01

    Recent observations of Type Ia SNe at redshifts 0 ~ 0.1 micron dust grains with a mass density of Omega_dust ~ (few) * 10^{-5} in the intergalactic (IG) medium. The same dust that dims the SNe absorbs the cosmic UV/optical background radiation around ~ 1 micron, and re-emits it at far infrared (FIR) wavelengths. Here we compare the FIR emission from IG dust with observations of the cosmic microwave (CMB) and cosmic far infrared backgrounds (FIRB) by the DIRBE/FIRAS instruments. We find that the emission would not lead to measurable distortion to the CMB, but would represent a substantial fraction (> 50 %) of the measured value of the FIRB in the 300-1000 micron range. This contribution would be consistent with the present unresolved fraction of the observed FIRB in an open universe. However, we find that IG dust probably could not reconcile the standard Omega=1 CDM model with the SN observations, even if the necessary quantity of dust existed. Future observations able to resolve the FIRB to a flux limit of ~ ...

  13. Cosmic Radiation - An Aircraft Manufacturer's View

    Energy Technology Data Exchange (ETDEWEB)

    Hume, C

    1999-07-01

    The relevance and context of cosmic radiation to an aircraft maker Airbus Industrie are outlined. Some future developments in aircraft and air traffic are described, along with their possible consequences for exposure. (author)

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

    Science.gov (United States)

    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.

  15. On the omnipresent background gamma radiation of the continuous spectrum

    Science.gov (United States)

    Banjanac, R.; Maletić, D.; Joković, D.; Veselinović, N.; Dragić, A.; Udovičić, V.; Aničin, I.

    2014-05-01

    The background spectrum of a germanium detector, shielded from the radiations arriving from the lower and open for the radiations arriving from the upper hemisphere, is studied by means of absorption measurements, both in a ground level and in an underground laboratory. The low-energy continuous portion of this background spectrum that peaks at around 100 keV, which is its most intense component, is found to be of very similar shape at the two locations. It is established that it is mostly due to the radiations of the real continuous spectrum, which is quite similar to the instrumental one. The intensity of this radiation is in our cases estimated to about 8000 photons/(m2s·2π·srad) in the ground level laboratory, and to about 5000 photons/(m2s·2π·srad) in the underground laboratory, at the depth of 25 m.w.e. Simulations by GEANT4 and CORSIKA demonstrate that this radiation is predominantly of terrestrial origin, due to environmental gamma radiations scattered off the materials that surround the detector (the "skyshine radiation"), and to a far less extent to cosmic rays of degraded energy.

  16. Cross correlation of Cosmic Microwave background and Weak Lensing

    CERN Document Server

    Lee, Seokcheon

    2015-01-01

    The integrated Sachs-Wolfe (ISW) effect and its non-linear extension Rees-Sciama (RS) effect provide us the information of the time evolution of gravitational potential. The cross-correlation between the cosmic microwave background (CMB) and the large scale structure (LSS) is known as a promising way to extract the ISW (RS) effect. It is known that the RS effect shows the unique behavior by changing the anti-correlated cross correlation between the CMB and the mass tracer into the positively correlated cross correlation compared to the linear ISW effect. We show that the dependence of this flipping scale of the cross-correlation between RS and weak lensing on dark energy models. However, there exists the degeneracy between DE and $\\Omega_{\\rm{m}0}$ which might be broken by redshift dependent observables. The cross-correlation between the momentum field and the density field might be served as the better observable to be used for this purpose.

  17. Comptonization of cosmic microwave background photons in dwarf spheroidal galaxies

    Science.gov (United States)

    Culverhouse, Thomas L.; Evans, N. Wyn; Colafrancesco, S.

    2006-05-01

    We present theoretical modelling of the electron distribution produced by annihilating neutralino dark matter in dwarf spheroidal galaxies (dSphs). In particular, we follow up the idea of Colafrancesco and find that such electrons distort the cosmic microwave background (CMB) by the Sunyaev-Zeldovich (SZ) effect. For an assumed neutralino mass of 10 GeV and beam size of 1 arcsec, the SZ temperature decrement is of the order of nano-Kelvin for dSph models with a soft core. By contrast, it is of the order of micro-Kelvin for the strongly cusped dSph models favoured by some cosmological simulations. Although this is out of reach of current instruments, it may well be detectable by future mm telescopes, such as the Atacama Large Millimetre Array. We also show that the upscattered CMB photons have energies within reach of upcoming X-ray observatories, but that the flux of such photons is too small to be detectable now. None the less, we conclude that searching for the dark matter induced SZ effect is a promising way of constraining the dark distribution in dSphs, especially if the particles are light.

  18. Comptonisation of Cosmic Microwave Background Photons in Dwarf Spheroidal Galaxies

    CERN Document Server

    Culverhouse, T L; Colafrancesco, S; Culverhouse, Thomas L.

    2006-01-01

    We present theoretical modelling of the electron distribution produced by annihilating neutralino dark matter in dwarf spheroidal galaxies (dSphs). In particular, we follow up the idea of Colafrancesco (2004) and find that such electrons distort the cosmic microwave background (CMB) by the Sunyaev-Zeldovich effect. For an assumed neutralino mass of 10 GeV and beam size of 1'', the SZ temperature decrement is of the order of nano-Kelvin for dSph models with a soft core. By contrast, it is of the order of micro-Kelvin for the strongly cusped dSph models favoured by some cosmological simulations. Although this is out of reach of current instruments, it may well be detectable by future mm telescopes, such as ALMA. We also show that the upscattered CMB photons have energies within reach of upcoming X-ray observatories, but that the flux of such photons is too small to be detectable soon. Nonetheless, we conclude that searching for the dark matter induced Sunyaev-Zeldovich effect is a promising way of constraining ...

  19. Cosmic microwave background polarization and temperature anisotropies from symmetric structures

    CERN Document Server

    Baccigalupi, C

    1999-01-01

    I explore the undulatory properties of the cosmic microwave background (CMB) physics. I consider the cases of spherical and cylindrical symmetry of the perturbation source, or seed. Such structures could have been left by high energy symmetries breaking in the early universe. I give suitable analytic expressions for the polarization and temperature linear perturbations from this kind of seeds and I show how to get their appearence on the CMB sky. This treatment highlights the undulatory properties of the CMB. I show with numerical examples how the polarization and temperature perturbations propagate beyond the size of their seeds, reaching the CMB sound horizon at the time considered. Just like the waves from a pebble thrown in a pond, the CMB anisotropy appears as a series of temperature and polarization waves surrounding the seed, extending on the scale of the CMB sound horizon at decoupling, roughly $1^{o}$ in the sky. Each wave is characterized by its own value of the CMB perturbation, with the same mean ...

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

    Science.gov (United States)

    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. Multiple Lensing of the Cosmic Microwave Background anisotropies

    CERN Document Server

    Calabrese, Matteo; Fabbian, Giulio; Baldi, Marco; Baccigalupi, Carlo

    2014-01-01

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

  2. Cosmic microwave background power spectrum estimation with the destriping technique

    Science.gov (United States)

    Poutanen, T.; Maino, D.; Kurki-Suonio, H.; Keihänen, E.; Hivon, E.

    2004-09-01

    Extraction of the cosmic microwave background (CMB) angular power spectrum is a challenging task for current and future CMB experiments due to the large data sets involved. Here we describe an implementation of Monte Carlo apodized spherical transform estimator (MASTER) described in Hivon et al., which exploits the destriping technique as a map-making method. In this method a noise estimate based on destriped noise-only Monte Carlo (MC) simulations is subtracted from the pseudo-angular power spectrum. As a working case we use realistic simulations of the Planck low-frequency instrument (LFI). We found that the effect of destriping on a pure sky signal is minimal and requires no correction. Instead we found an effect related to the distribution of detector pointings, which affects the high-l part of the power spectrum. We correct for this by subtracting a `signal bias' estimated by MC simulations. We also give analytical estimates for this signal bias. Our method is fast and accurate enough (the estimator is unbiased and errors are close to theoretical expectations for maximal accuracy) to estimate the CMB angular power spectra for current and future CMB space missions. This study is related to Planck LFI activities.

  3. Cosmic microwave background power spectrum estimation with the destriping technique

    CERN Document Server

    Poutanen, T; Kurki-Suonio, H; Keihanen, E; Hivon, E

    2004-01-01

    Extraction of the CMB (Cosmic Microwave Background) angular power spectrum is a challenging task for current and future CMB experiments due to the large data sets involved. Here we describe an implementation of MASTER (Monte carlo Apodised Spherical Transform EstimatoR) which exploits the destriping technique as a map-making method. In this method a noise estimate based on destriped noise-only MC (Monte Carlo) simulations is subtracted from the pseudo angular power spectrum. As a working case we use realistic simulations of the PLANCK LFI (Low Frequency Instrument). We found that the effect of destriping on a pure sky signal is minimal and requires no correction. Instead we found an effect related to the distribution of detector pointings, which affects the high multipole part of the power spectrum. We correct for this by subtracting a ``signal bias'' estimated by MC simulations. We also give analytical estimates for this signal bias. Our method is fast and accurate enough (the estimator is un-biased and erro...

  4. Non-linear evolution of the cosmic neutrino background

    CERN Document Server

    Villaescusa-Navarro, Francisco; Peña-Garay, Carlos; Viel, Matteo

    2012-01-01

    We investigate the non-linear evolution of the relic cosmic neutrino background by running large box-size, high resolution N-body simulations. Our set of simulations explore the properties of neutrinos in a reference $\\Lambda$CDM model with total neutrino masses between 0.05-0.60 eV in cold dark matter haloes of mass $10^{11}-10^{15}$ $h^{-1}$M$_{\\odot}$, 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. 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 ...

  5. Delensing the CMB with the Cosmic Infrared Background

    CERN Document Server

    Sherwin, Blake D

    2015-01-01

    As confusion with lensing B-modes begins to limit experiments that search for primordial B-mode polarization, robust methods for delensing the CMB polarization sky are becoming increasingly important. We investigate in detail the possibility of delensing the CMB with the cosmic infrared background (CIB), emission from dusty star-forming galaxies that is an excellent tracer of the CMB lensing signal, in order to improve constraints on the tensor-to-scalar ratio $r$. We find that the maps of the CIB, such as current Planck satellite maps at 545 GHz, can be used to remove more than half of the lensing B-mode power. Calculating optimal combinations of different large-scale-structure tracers for delensing, we find that co-adding CIB data and external arcminute-resolution CMB lensing reconstruction can lead to significant additional improvements in delensing performance. We investigate whether measurement uncertainty in the CIB spectra will degrade the delensing performance if no model of the CIB spectra is assumed...

  6. The information content of cosmic microwave background anisotropies

    CERN Document Server

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

    2016-01-01

    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 illustrate. 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 ...

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

    CERN Document Server

    Saadeh, Daniela; Pontzen, Andrew; Peiris, Hiranya V; McEwen, Jason D

    2016-01-01

    We present a new framework for testing the isotropy of the Universe using cosmic microwave background data, building on the nested-sampling ANICOSMO code. Uniquely, we are able to constrain the scalar, vector and tensor degrees of freedom alike; previous studies only considered the vector mode (linked to vorticity). We employ Bianchi type VII$_h$ cosmologies to model the anisotropic Universe, from which other types may be obtained by taking suitable limits. In a separate development, we improve the statistical analysis by including the effect of Bianchi power in the high-$\\ell$, as well as the low-$\\ell$, likelihood. To understand the effect of all these changes, we apply our new techniques to WMAP data. We find no evidence for anisotropy, constraining shear in the vector mode to $(\\sigma_V/H)_0 < 1.7 \\times 10^{-10}$ (95% CL). For the first time, we place limits on the tensor mode; unlike other modes, the tensor shear can grow from a near-isotropic early Universe. The limit on this type of shear is $(\\sig...

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

    Science.gov (United States)

    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. A circular polarimeter for the Cosmic Microwave Background

    CERN Document Server

    Giovannini, Massimo

    2010-01-01

    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 ou...

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

    Science.gov (United States)

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

    2016-10-01

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

  11. Reconstruction of lensing from the cosmic microwave background polarization

    CERN Document Server

    Hirata, C M; Hirata, Christopher M.; Seljak, Uros

    2003-01-01

    Gravitational lensing of the cosmic microwave background (CMB) polarization field has been recognized as a potentially valuable probe of the cosmological density field. We apply likelihood-based techniques to the problem of lensing of CMB polarization and show that if the B-mode polarization is mapped, then likelihood-based techniques allow significantly better lensing reconstruction than is possible using the previous quadratic estimator approach. With this method the ultimate limit to lensing reconstruction is not set by the lensed CMB power spectrum. Second-order corrections are known to produce a curl component of the lensing deflection field that cannot be described by a potential; we show that this does not significantly affect the reconstruction at noise levels greater than 0.25 microK arcmin. The reduction of the mean squared error in the lensing reconstruction relative to the quadratic method can be as much as a factor of two at noise levels of 1.4 microK arcmin to a factor of ten at 0.25 microK arcm...

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

    Directory of Open Access Journals (Sweden)

    Seokcheon Lee

    2015-06-01

    Full Text Available 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.

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

    Science.gov (United States)

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

    2017-01-01

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

  14. Cosmic Sculpture: A new way to visualise the Cosmic Microwave Background

    CERN Document Server

    Clements, D L; Fonseca, A Portela

    2016-01-01

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

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.; Lisse, C.M.; Moseley, S.H. Jr.; Shafer, R.A.; Silverberg, R.F.; Spiesman, W.J.; Toller, G.N.; Weiland, J.L. (Laboratory for Astronomy and Solar Physics, Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)); Gulkis, S.; Jansssen, M. (Jet Propulsion Laboratory, MS 169-506, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)); Lubin, P.M. (UCSB Department of Physics, Goleta, California 93106 (United States)); Meyer, S.S.; Weiss, R. (Room 20F-001, Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)); Murdock, T.L. (General Research Corporation, 5 Cherry Hill Drive, Suite 220, Danvers, Massachusetts 01923 (United States)); Smoot, G.F. (Lawrence Berkeley Laboratory, 50-232, University of California, Berkeley, California 94720 (United States)); Wilkinson, D.T. (Dep

    1992-01-10

    The Cosmic Background Explorer, launched November 18, 1989, has nearly completed its first full mapping of the sky with all three of its instruments: a Far Infrared Absolute Spectrophotometer (FIRAS) covering 0.1 to 10 mm, a set of Differential Microwave Radiometers (DMR) operating at 3.3, 5.7, and 9.6 mm, and a Diffuse Infrared Background Experiment (DIRBE) spanning 1 to 300 {mu}m in ten bands. A preliminary map of the sky derived from DIRBE data is presented. Initial cosmological implications include: a limit on the Comptonization {ital y} parameter of 10{sup {minus}3}, on the chemical potential {mu} parameter of 10{sup {minus}2}, a strong limit on the existence of a hot smooth intergalactic medium, and a confirmation that the dipole anisotropy has the spectrum expected from a Doppler shift of a blackbody. There are no significant anisotropies in the microwave sky detected, other than from our own galaxy and a cos {theta} dipole anisotropy whose amplitude and direction agree with previous data. At shorter wavelengths, the sky spectrum and anisotropies are dominated by emission from local' sources of emission within our Galaxy and Solar System. Preliminary comparison of {ital IRAS} and {ital DIRBE} sky brightnesses toward the ecliptic poles shows the {ital IRAS} values to be significantly higher than found by {ital DIRBE} at 100 {mu}m. We suggest the presence of gain and zero-point errors in the {ital IRAS} total brightness data. The spacecraft, instrument designs, and data reduction methods are described.

  17. Electromagnetic wave collapse in a radiation background.

    Science.gov (United States)

    Marklund, Mattias; Brodin, Gert; Stenflo, Lennart

    2003-10-17

    The nonlinear interaction, due to quantum electrodynamical (QED) effects between an electromagnetic pulse and a radiation background, is investigated by combining the methods of radiation hydrodynamics with the QED theory for photon-photon scattering. For the case of a single coherent electromagnetic pulse, we obtain a Zakharov-like system, where the radiation pressure of the pulse acts as a driver of acoustic waves in the photon gas. For a sufficiently intense pulse and/or background energy density, there is focusing and the subsequent collapse of the pulse. The relevance of our results for various astrophysical applications are discussed.

  18. The source of cosmic radiations; A la source des rayons cosmiques

    Energy Technology Data Exchange (ETDEWEB)

    Letessier-Selvon, A. [Laboratoire de Physique Nucleaire et Hautes Energies, 75 - Paris (France)

    2008-11-15

    The existence of the GZD (Greisen-Zatsepin-Kuzmin) limit comes from the fact that the cosmological diffuse background interacts with cosmological radiations and can reduce dramatically their energy. As a consequence cosmic radiations traveling over large intergalactic distances can not have an energy over 60*10{sup 18} eV (the GZK limit). Another consequence is that a cosmic radiation with an energy greater that the GZK limit comes necessarily from a region no more than 500 million light-years away. The Auger observatory that at term will cover a surface of 3000 km{sup 2} has been designed to study high energy cosmic radiations through the detection of the huge particle showers they trigger when interacting with particles from the upper part of the atmosphere. The first results of the Auger observatory shows three important things. First, the Auger detector's ability to detect is 30 times greater than that of previous experiments. Secondly, 27 events with an energy greater than the GZK limit have been detected and for 20 of them a very active galaxy is located in their incident direction within a distance of 300*10{sup 6} km, these galaxies are then highly suspected to be the source of very high energy cosmic radiations. Thirdly, the graph of the measured cosmic radiation flux shows a brutal drop around 60*10{sup 18} eV which is the GZK limit. (A.C.)

  19. Constraining Primordial Black-Hole Bombs through Spectral Distortions of the Cosmic Microwave Background

    CERN Document Server

    Pani, Paolo

    2013-01-01

    We consider the imprint of superradiant instabilities of nonevaporating primordial black holes (PBHs) on the spectrum of the cosmic microwave background (CMB). In the radiation dominated era, PBHs are surrounded by a roughly homogeneous cosmic plasma which endows photons with an effective mass through the plasma frequency. In this setting, spinning PBHs are unstable to a spontaneous spindown through the well-known "black-hole bomb" mechanism. At linear level, the photon density is trapped by the effective photon mass and grows exponentially in time due to superradiance. As the plasma density declines due to cosmic expansion, the associated energy around PBHs is released and dissipated in the CMB. We evaluate the resulting spectral distortions of the CMB in the redshift range 10^3 < z < 2x10^6. Using the existing COBE/FIRAS bounds on CMB spectral distortions, we derive upper limits on the fraction of dark matter that can be associated with spinning PBHs in the mass range 10^{-8}*Msun < M < 0.2*Msin...

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

    Science.gov (United States)

    Pani, Paolo; Loeb, Abraham

    2013-08-01

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

  1. Cosmic microwave background constraints on a decaying cosmological term related to the thermal evolution

    CERN Document Server

    Nakamura, Riou; Ichiki, Kiyotomo

    2008-01-01

    We constrain the thermal evolution of the universe with a decaying cosmological term by using the method of the analysis for the Wilkinson Microwave Anisotropy Probe (WMAP) observation data. The cosmological term is assumed to be a function of the scale factor that increases toward the early universe, and the radiation energy density is lower compared to that in the model with the standard cosmological "constant" (LCDM). The decrease in the radiation density affects the thermal history of the universe; e.g. the photon decoupling occurs at higher-z compared to the case of the standard LCDM model. As a consequence, a decaying cosmological term affects the cosmic microwave background anisotropy. Thanks to the Markov-chain Monte Carlo method, we compare the angular power spectrum in the decaying LCDM model with the CMB data, and we get severe constraints on parameters of the model.

  2. Imprint of DES superstructures on the cosmic microwave background

    Science.gov (United States)

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

    2017-03-01

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

  3. Imprint of DES superstructures on the cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-17

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

  4. Measuring the cosmic microwave background polarization with POLARBEAR

    Science.gov (United States)

    Barron, Darcy; Polarbear Collaboration

    2015-01-01

    POLARBEAR is a cosmic microwave background (CMB) polarization experiment located in the Atacama desert in Chile. POLARBEAR-1 started observations in 2012, and in 2014, the POLARBEAR team published results from its first season of observations on a small fraction of the sky. These results include the first measurement of a non-zero B-mode polarization angular power spectrum, measured at sub-degree scales where the dominant signal is gravitational lensing of the CMB. We also published a measurement of the large-scale gravitational structure deflection power spectrum derived from CMB polarization alone, which demonstrates a powerful technique that can be used to measure nearly all of the gravitational structure in the universe. Improving these measurements requires precision characterization of the CMB polarization signal over large fractions of the sky, at multiple frequencies. To achieve these goals, POLARBEAR has begun expanding to include an additional two 3.5 meter telescopes with multi-chroic receivers, known as the Simons Array. Phased upgrades to receiver technology will improve sensitivity and capabilities, while continuing a deep survey of 80% of the sky. POLARBEAR-2 is the next receiver that will be installed in 2015 on a new telescope, with a larger area focal plane with dichroic pixels, with bands at 95 GHz and 150 GHz, and a total of 7,588 polarization sensitive antenna-coupled transition edge sensor bolometers. The focal plane is cooled to 250 milliKelvin, and the bolometers will be read-out by SQUID amplifiers with 40x frequency domain multiplexing. The array is designed to have a noise equivalent temperature of 5.7 μK√s.

  5. Skewness in the Cosmic Microwave Background Anisotropy from Inflationary Gravity Wave Background

    CERN Document Server

    Bharadwaj, S; Souradeep, T; Bharadwaj, Somnath; Munshi, Dipak; Souradeep, Tarun

    1997-01-01

    In the context of inflationary scenarios, the observed large angle anisotropy of the Cosmic Microwave Background (CMB) temperature is believed to probe the primordial metric perturbations from inflation. Although the perturbations from inflation are expected to be gaussian random fields, there remains the possibility that nonlinear processes at later epochs induce ``secondary'' non-gaussian features in the corresponding CMB anisotropy maps. The non-gaussianity induced by nonlinear gravitational instability of scalar (density) perturbations has been investigated in existing literature. In this paper, we highlight another source of non-gaussianity arising out of higher order scattering of CMB photons off the metric perturbations. We provide a simple and elegant formalism for deriving the CMB temperature fluctuations arising due to the Sachs-Wolfe effect beyond the linear order. In particular, we derive the expression for the second order CMB temperature fluctuations. The multiple scattering effect pointed out i...

  6. Design of a transition radiation detector for cosmic rays

    Science.gov (United States)

    Hartmann, G.; Mueller, D.; Prince, T.

    1975-01-01

    Transition radiation detectors consisting of sandwiches of plastic foam radiators and multiwire proportional chambers can be used to identify cosmic ray particles with energies gamma ? E/mc-squared is greater than 10 to the 3rd and to measure their energy in the region gamma is roughly equal to 10 to the 3rd

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

    CERN Document Server

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

    2009-01-01

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

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

    Science.gov (United States)

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

    2012-08-01

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

  9. Cosmic radiations; A la rencontre des rayons cosmiques

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2011-09-15

    Cosmic radiations were discovered one century ago, they were detected indirectly by their positive effect on the conductivity of the air through the ionization of atoms and molecules composing the air. The first measurement made on balloons showed that the ionization was increasing with altitude which discredited the idea that the radiations were coming from the earth itself. Other measurement campaigns showed that the cosmic radiations were very low at the equator which supported the idea that cosmic radiations were made up of charged particles that are deflected by the earth magnetic field. During the forties and the fifties the study of cosmic radiations led to the discovery of a broad range of particles: positrons, muons, pions, kaons and hyperons. The first observations on stratospheric balloons confirmed the origin of the showers of particles that had been detected with a series of ground detectors dispatched on a large area a few years before. These showers of particles are produced by primary cosmic rays mainly energetic protons colliding with nitrogen and oxygen atoms of the atmosphere. (A.C.)

  10. Water, air, Earth and cosmic radiation.

    Science.gov (United States)

    Bassez, Marie-Paule

    2015-06-01

    In the context of the origin of life, rocks are considered mainly for catalysis and adsorption-desorption processes. Here it is shown how some rocks evolve in energy and might induce synthesis of molecules of biological interest. Radioactive rocks are a source of thermal energy and water radiolysis producing molecular hydrogen, H2. Mafic and ultramafic rocks evolve in water and dissolved carbon dioxide releasing thermal energy and H2. Peridotites and basalts contain ferromagnesian minerals which transform through exothermic reactions with the generation of heat. These reactions might be triggered by any heating process such as radioactive decay, hydrothermal and subduction zones or post-shock of meteorite impacts. H2 might then be generated from endothermic hydrolyses of the ferromagnesian minerals olivine and pyroxene. In both cases of mafic and radioactive rocks, production of CO might occur through high temperature hydrogenation of CO2. CO, instead of CO2, was proven to be necessary in experiments synthesizing biological-type macromolecules with a gaseous mixture of CO, N2 and H2O. In the geological context, N2 is present in the environment, and the activation source might arise from cosmic radiation and/or radionuclides. Ferromagnesian and radioactive rocks might consequently be a starting point of an hydrothermal chemical evolution towards the abiotic formation of biological molecules. The two usually separate worlds of rocks and life are shown to be connected through molecular and thermodynamic chemical evolution. This concept has been proposed earlier by the author (Bassez J Phys: Condens Matter 15:L353-L361, 2003, 2008a, 2008b; Bassez Orig Life Evol Biosph 39(3-4):223-225, 2009; Bassez et al. 2011; Bassez et al. Orig Life Evol Biosph 42(4):307-316, 2012, Bassez 2013) without thermodynamic details. This concept leads to signatures of prebiotic chemistry such as radionuclides and also iron and magnesium carbonates associated with serpentine and/or talc

  11. Water, Air, Earth and Cosmic Radiation

    Science.gov (United States)

    Bassez, Marie-Paule

    2015-06-01

    In the context of the origin of life, rocks are considered mainly for catalysis and adsorption-desorption processes. Here it is shown how some rocks evolve in energy and might induce synthesis of molecules of biological interest. Radioactive rocks are a source of thermal energy and water radiolysis producing molecular hydrogen, H2. Mafic and ultramafic rocks evolve in water and dissolved carbon dioxide releasing thermal energy and H2. Peridotites and basalts contain ferromagnesian minerals which transform through exothermic reactions with the generation of heat. These reactions might be triggered by any heating process such as radioactive decay, hydrothermal and subduction zones or post-shock of meteorite impacts. H2 might then be generated from endothermic hydrolyses of the ferromagnesian minerals olivine and pyroxene. In both cases of mafic and radioactive rocks, production of CO might occur through high temperature hydrogenation of CO2. CO, instead of CO2, was proven to be necessary in experiments synthesizing biological-type macromolecules with a gaseous mixture of CO, N2 and H2O. In the geological context, N2 is present in the environment, and the activation source might arise from cosmic radiation and/or radionuclides. Ferromagnesian and radioactive rocks might consequently be a starting point of an hydrothermal chemical evolution towards the abiotic formation of biological molecules. The two usually separate worlds of rocks and life are shown to be connected through molecular and thermodynamic chemical evolution. This concept has been proposed earlier by the author (Bassez J Phys: Condens Matter 15:L353-L361, 2003, 2008a, 2008b; Bassez Orig Life Evol Biosph 39(3-4):223-225, 2009; Bassez et al. 2011; Bassez et al. Orig Life Evol Biosph 42(4):307-316, 2012, Bassez 2013) without thermodynamic details. This concept leads to signatures of prebiotic chemistry such as radionuclides and also iron and magnesium carbonates associated with serpentine and/or talc, which

  12. Cosmic microwave background polarization in Noncommutative space-time

    CERN Document Server

    Batebi, S; Mohammadi, R; Tizchang, S

    2016-01-01

    In the standard model of cosmology (SMC) the B-mode polarization of the CMB can be explained by the gravitational effects in the inflation epoch. However, this is not the only way to explain the B-mode polarization for the CMB. It can be shown that the Compton scattering in presence of a background besides generating a circularly polarized microwave, can leads to a B-mode polarization for the CMB. Here we consider the non-commutative (NC) space time as a background to explore the CMB polarization at the last scattering surface. We obtain the B-mode spectrum of the CMB radiation by scalar perturbation of metric via a correction on the Compton scattering in NC-space-time in terms of the circular polarization power spectrum and the non-commutative energy scale. It can be shown that even for the NC-scale as large as $10TeV$ the NC-effects on the CMB polarization and the r-parameter is significant. We show that the V-mode power spectrum can be obtained in terms of linearly polarized power spectrum in the range Mic...

  13. Non-linear evolution of the cosmic neutrino background

    Energy Technology Data Exchange (ETDEWEB)

    Villaescusa-Navarro, Francisco; Viel, Matteo [INAF/Osservatorio Astronomico di Trieste, Via Tiepolo 11, 34143, Trieste (Italy); Bird, Simeon [Institute for Advanced Study, 1 Einstein Drive, Princeton, NJ, 08540 (United States); Peña-Garay, Carlos, E-mail: villaescusa@oats.inaf.it, E-mail: spb@ias.edu, E-mail: penya@ific.uv.es, E-mail: viel@oats.inaf.it [Instituto de Física Corpuscular, CSIC-UVEG, E-46071, Paterna, Valencia (Spain)

    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

  14. Galactic cosmic ray radiation levels in spacecraft on interplanetary missions

    Science.gov (United States)

    Shinn, J. L.; Nealy, J. E.; Townsend, L. W.; Wilson, J. W.; Wood, J.S.

    1994-01-01

    Using the Langley Research Center Galactic Cosmic Ray (GCR) transport computer code (HZETRN) and the Computerized Anatomical Man (CAM) model, crew radiation levels inside manned spacecraft on interplanetary missions are estimated. These radiation-level estimates include particle fluxes, LET (Linear Energy Transfer) spectra, absorbed dose, and dose equivalent within various organs of interest in GCR protection studies. Changes in these radiation levels resulting from the use of various different types of shield materials are presented.

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

    Energy Technology Data Exchange (ETDEWEB)

    McMath, Garrett E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Engineering and Nonproliferation Div.; McKinney, Gregg W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Engineering and Nonproliferation Div.; Wilcox, Trevor [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Engineering and Nonproliferation Div.

    2015-01-23

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

  16. Cosmic Muon Induced Backgrounds in the Daya Bay Reactor Neutrino Experiment

    CERN Document Server

    Dengjie, Li

    2014-01-01

    Muon induced neutrons and long-lived radioactive isotopes are important background sources for low-energy underground experiments. We study the produced processes and properties of cosmic muon induced backgrounds, show the muon veto system used for rejecting these backgrounds and the methods to estimate residual backgrounds in the Daya Bay Reactor Neutrino Experiment.

  17. Cosmic microwave background bispectrum of tensor passive modes induced from primordial magnetic fields

    CERN Document Server

    Shiraishi, Maresuke; Yokoyama, Shuichiro; Ichiki, Kiyotomo; Takahashi, Keitaro

    2011-01-01

    If the seed magnetic fields exist in the early Universe, tensor components of their anisotropic stresses are not compensated prior to neutrino decoupling and the tensor metric perturbations generated from them survive passively. Consequently, due to the decay of these metric perturbations after recombination, so-called, integrated Sachs-Wolfe effect, the large-scale fluctuations of the cosmic microwave background (CMB) radiation are significantly boosted. This kind of the CMB anisotropy is called "tensor passive mode". Because these fluctuations deviate largely from the Gaussian statistics due to the quadratic dependence on the strength of the Gaussian magnetic field, not only the power spectrum but also the higher-order correlations have reasonable signals. With these motives, we compute the CMB bispectrum induced by this mode. When the magnetic spectrum obeys a nearly scale-invariant shape, we obtain an estimation of a typical value of the normalized reduced bispectrum as $\\ell_1(\\ell_1 + 1)\\ell_3(\\ell_3+1)...

  18. A balloon-borne millimeter-wave telescope for cosmic microwave background anisotropy measurements

    CERN Document Server

    Fixsen, D J; Cottingham, D A; Folz, W C; Inman, C A; Kowitt, M S; Meyer, S; Page, L A; Puchalla, J L; Ruhl, J E; Silverberg, R F

    1995-01-01

    We report on the characteristics and design details of the Medium Scale Anisotropy Measurement (MSAM), a millimeter-wave, balloon-borne telescope that has been used to observe anisotropy in the Cosmic Microwave Background Radiation (CMBR) on 0\\fdg5 angular scales. The gondola is capable of determining and maintaining absolute orientation to a few arcminutes during a one-night flight. Emphasis is placed on the optical and pointing performance as well as the weight and power budgets. We also discuss the total balloon/gondola mechanical system. The pendulation from this system is a ubiquitous perturbation on the pointing system. A detailed understanding in these areas is needed for developing the next generation of balloon-borne instruments.

  19. Uniformity of Cosmic Microwave Background as a Non-Inflationary Geometrical Effect

    CERN Document Server

    Vlahovic, Branislav; Ilie, Cosmin

    2015-01-01

    The conventional $\\Lambda$CDM cosmological model supplemented by the inflation concept describes the Universe very well. However, there are still a few concerns: new Planck data impose constraints on the shape of the inflaton potential, which exclude a lot of inflationary models; dark matter is not detected directly, and dark energy is not understood theoretically on a satisfactory level. In this brief sketch we investigate an alternative cosmological model with spherical spatial geometry and an additional perfect fluid with the constant parameter $\\omega=-1/3$ in the linear equation of state. It is demonstrated explicitly that in the framework of such a model it is possible to satisfy the supernovae data at the same level of accuracy as within the $\\Lambda$CDM model and at the same time suppose that the observed cosmic microwave background (CMB) radiation originates from a very limited space region. This is ensured by introducing an additional condition of light propagation between the antipodal points durin...

  20. Testing theories of Gravity and Supergravity with inflation and observations of the cosmic microwave background

    CERN Document Server

    Chakravarty, Girish Kumar; Mohanty, Subhendra

    2016-01-01

    Many extensions of Einstein's theory of gravity have been studied and proposed with various motivations like the quest for a quantum theory of gravity to extensions of anomalies in observations at the solar system, galactic and cosmological scales. These extensions include adding higher powers of Ricci curvature $R$, coupling the Ricci curvature with scalar fields and generalized functions of $R$. In addition when viewed from the perspective of Supergravity (SUGRA) many of these theories may originate from the same SUGRA theory interpreted in different frames. SUGRA therefore serves as a good framework for organizing and generalizing theories of gravity beyond General Relativity. All these theories when applied to inflation (a rapid expansion of early Universe in which primordial gravitational waves might be generated and might still be detectable by the imprint they left or by the ripples that persist today) can have distinct signatures in the Cosmic Microwave Background radiation temperature and polarizatio...

  1. Cosmic Microwave Background and Density Fluctuations from Strings plus Inflation

    CERN Document Server

    Contaldi, C; Magueijo, J; Contaldi, Carlo; Hindmarsh, Mark; Magueijo, Joao

    1999-01-01

    In cosmological models where local cosmic strings are formed at the end of a period of inflation, the perturbations are seeded both by the defects and by the quantum fluctuations. In a subset of these models, for example those based on $D$-term inflation, the amplitudes are similar. Using our recent calculations of structure formation with cosmic strings, we point out that in a flat cosmology with zero cosmological constant and 5% baryonic component, strings plus inflation fits the observational data much better than each component individually. The large-angle CMB spectrum is mildly tilted, for Harrison-Zeldovich inflationary fluctuations. It then rises to a thick Doppler bump, covering $\\ell=200-600$, modulated by soft secondary undulations. The standard CDM anti-biasing problem is cured, giving place to a slightly biased scenario of galaxy formation.

  2. Relic Right-handed Dirac Neutrinos and Implications for Detection of Cosmic Neutrino Background

    CERN Document Server

    Zhang, Jue

    2015-01-01

    It remains to be determined experimentally if massive neutrinos are Majorana or Dirac particles. In this connection, it has been recently suggested that the detection of cosmic neutrino background of left-handed neutrinos $\

  3. Cosmic Microwave Background Anisotropies from Scaling Seeds Fit to Observational Data

    OpenAIRE

    Durrer, Ruth; Kunz, Martin; Lineweaver, C. H.; Sakellariadou, Mairi

    1997-01-01

    We compute cosmic microwave background angular power spectra for scaling seed models of structure formation. A generic parameterization of the energy momentum tensor of the seeds is employed. We concentrate on two regions of parameter space inspired by global topological defects: O(4) texture models and the large-N limit of O(N) models. We use $\\chi^{2}$ fitting to compare these models to recent flat-band power measurements of the cosmic microwave background. Only scalar perturbations are con...

  4. Gravitational Collapse of Radiating Dyon Solution and Cosmic Censorship Hypothesis

    Institute of Scientific and Technical Information of China (English)

    K.D.Patil; S.S.Zade; A.N.Mohod

    2008-01-01

    @@ We investigate the possibifity of cosmic censorship violation in the gravitational collapse of radiating dyon solution.It is shown that the final outcome of the collapse depends sensitively on the electric and magnetic charge parameters.The graphs of the outer apparent horizon,inner Cauchy horizon for different values of parameters are drawn.

  5. Cosmic microwave background experiments targeting the cosmic strings Doppler peak signal

    CERN Document Server

    Magueijo, J; Magueijo, Joao; Hobson, Mike

    1996-01-01

    We investigate which experiments are better suited to test the robust prediction that cosmic strings do not produce secondary Doppler peaks. We propose a statistic for detecting oscillations in the C^l spectrum, and study its statistical relevance given the truth of an inflationary competitor to cosmic strings. The analysis is performed for single-dish experiments and interferometers, subject to a variety of noise levels and scanning features. A high resolution of 0.2 degrees is found to be required for single-dish experiments with realistic levels of noise. Interferometers appear to be more suitable for detecting this signal.

  6. Cosmic Strings and Their Induced Non-Gaussianities in the Cosmic Microwave Background

    Directory of Open Access Journals (Sweden)

    Christophe Ringeval

    2010-01-01

    small fraction of the CMB angular power spectrum, cosmic strings could actually be the main source of its non-Gaussianities. In this paper, after having reviewed the basic cosmological properties of a string network, we present the signatures Nambu-Goto cosmic strings would induce in various observables ranging from the one-point function of the temperature anisotropies to the bispectrum and trispectrum. It is shown that string imprints are significantly different than those expected from the primordial type of non-Gaussianity and could therefore be easily distinguished.

  7. Remaining Problems in Interpretation of the Cosmic Microwave Background

    Directory of Open Access Journals (Sweden)

    Hans-Jörg Fahr

    2015-01-01

    Full Text Available By three independent hints it will be demonstrated that still at present there is a substantial lack of theoretical understanding of the CMB phenomenon. One point, as we show, is that at the phase of the recombination era one cannot assume complete thermodynamic equilibrium conditions but has to face both deviations in the velocity distributions of leptons and baryons from a Maxwell-Boltzmann distribution and automatically correlated deviations of photons from a Planck law. Another point is that at the conventional understanding of the CMB evolution in an expanding universe one has to face growing CMB temperatures with growing look-back times. We show, however, here that the expected CMB temperature increases would be prohibitive to star formation in galaxies at redshifts higher than z=2 where nevertheless the cosmologically most relevant supernovae have been observed. The third point in our present study has to do with the assumption of a constant vacuum energy density which is required by the present ΛCDM-cosmology. Our studies here rather lead to the conclusion that cosmic vacuum energy density scales with the inverse square of the cosmic expansion scale R=R(t. Thus we come to the conclusion that with the interpretation of the present-day high quality CMB data still needs to be considered carefully.

  8. Cosmic Microwave Background Anisotropy Induced by Cosmic Strings on Angular Scales {approx_gt}15{sup {prime} }

    Energy Technology Data Exchange (ETDEWEB)

    Allen, B. [Department of Physics, University of Wisconsin---Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201 (United States); Caldwell, R.R. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19106 (United States); Dodelson, S.; Stebbins, A. [NASA/Fermilab Astrophysics Center, P.O. Box 500, Batavia, Illinois 60510 (United States); Knox, L. [Canadian Institute for Theoretical Astrophysics, Toronto, Ontario, M5S 3H8 (Canada); Shellard, E.P. [University of Cambridge, D.A.M.T.P. Silver Street, Cambridge CB3 9EW (United Kingdom)

    1997-10-01

    We have computed an estimate of the angular power spectrum of the cosmic microwave background induced by cosmic strings on angular scales {approx_gt}15{sup {prime}}, using a numerical simulation of a cosmic string network and have decomposed this pattern into scalar, vector, and tensor parts. The anisotropies from vector modes dominate except on very small angular scales, and we find no evidence for strong acoustic oscillations in the scalar anisotropy. The anisotropies generated after recombination are even more important than in adiabatic models. The total anisotropy on small scales is inconsistent with current measurements. The calculation has a number of uncertainties, the largest of which is due to finite temporal range. {copyright} {ital 1997} {ital The American Physical Society}

  9. Nonlinear evolution of cosmic magnetic fields and cosmic microwave background anisotropies

    Science.gov (United States)

    Tashiro, Hiroyuki; Sugiyama, Naoshi; Banerjee, Robi

    2006-01-01

    In this work we investigate the effects of primordial magnetic fields on cosmic microwave background anisotropies (CMB). Based on cosmological magneto-hydro dynamic (MHD) simulations [R. Banerjee and K. Jedamzik, Phys. Rev. DPRVDAQ0556-2821 70, 123003 (2004).10.1103/PhysRevD.70.123003] we calculate the CMB anisotropy spectra and polarization induced by fluid fluctuations (Alfvén modes) generated by primordial magnetic fields. The strongest effect on the CMB spectra comes from the transition epoch from a turbulent regime to a viscous regime. The balance between magnetic and kinetic energy until the onset of the viscous regime provides a one to one relation between the comoving coherence length L and the comoving magnetic field strength B, such as L˜30(B/10-9Gauss)3pc. The resulting CMB temperature and polarization anisotropies for the initial power law index of the magnetic fields n>3/2 are somewhat different from the ones previously obtained by using linear perturbation theory. In particular, differences can appear on intermediate scales l20000. On scales l0.7Mpc for the most extreme case, or B0.8Mpc for the most conservative case. We may also expect higher signals on large scales of the polarization spectra compared to linear calculations. The signal may even exceed the B-mode polarization from gravitational lensing depending on the strength of the primordial magnetic fields. On very small scales, the diffusion damping scale of nonlinear calculations turns out to be much smaller than the one of linear calculations if the comoving magnetic field strength B>16nGauss. If the magnetic field strength is smaller, the diffusion scales become smaller too. Therefore we expect to have both, temperature and polarization anisotropies, even beyond l>10000 regardless of the strength of the magnetic fields. The peak values of the temperature anisotropy and the B-mode polarization spectra are approximately 40μK and a few μK, respectively.

  10. Cosmic microwave background anomalies in an open universe.

    Science.gov (United States)

    Liddle, Andrew R; Cortês, Marina

    2013-09-13

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

  11. The impact of superstructures in the Cosmic Microwave Background

    Science.gov (United States)

    Ilić, Stéphane; Langer, Mathieu; Douspis, Marian

    2016-10-01

    In 2008, Granett et al. claimed a direct detection of the integrated Sachs-Wolfe (iSW) effect, through the stacking of CMB patches at the positions of identified superstructures. Additionally, the high amplitude of their measured signal was reported to be at odds with predictions from the standard model of cosmology. However, a closer inspection of these results prompts multiple questions, more specifically about the amplitude and significance of the expected signal. We propose here an original theoretical prediction of the iSW effect produced by such superstructures. We use simulations based on GR and the LTB metric to reproduce cosmic structures and predict their exact theoretical iSW effect on the CMB. The amplitudes predicted with this method are consistent with the signal measured when properly accounting the contribution of the non-negligible (and fortuitous) primordial CMB fluctuations to the total signal. It also highlights the tricky nature of stacking measurements and their interpretation.

  12. Inter-galactic Shock Acceleration and the Cosmic Gamma-ray Background

    CERN Document Server

    Miniati, F

    2002-01-01

    We investigate numerically the contribution to the cosmic gamma-ray background from cosmic-rays ions and electrons accelerated at inter-galactic (IG) shocks associated with cosmological structure formation. We show that the kinetic energy of accretion flows in the low-red-shift IG 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 pions generated in p-p inelastic collisions of the ionic cosmic-ray component with the thermal gas contribute about 30% 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 energy into relativistic CR electrons to less than 1%. Thus, we find that cosmic-rays of cosmologi...

  13. Cosmic Strings as the Source of Small-Scale Microwave Background Anisotropy

    CERN Document Server

    Pogosian, Levon; Wasserman, Ira; Wyman, Mark

    2008-01-01

    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 (l2000) 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.

  14. Cosmic Ray contribution to the WMAP polarization data on the Cosmic Microwave Background

    CERN Document Server

    Wibig, Tadeusz

    2015-01-01

    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 foreground' for the CMB. We have given special attention to high Galactic latitudes, where the recent BICEP2 findings were reported. 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 cosmic rays is still observed even at high Galactic altitudes 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.

  15. Reproducing the observed Cosmic microwave background anisotropies with causal scaling seeds

    OpenAIRE

    Durrer, R.; Kunz, M.; Melchiorri, A.

    2000-01-01

    During the last years it has become clear that global O(N) defects and U(1) cosmic strings do not lead to the pronounced first acoustic peak in the power spectrum of anisotropies of the cosmic microwave background which has recently been observed to high accuracy. Inflationary models cannot easily accommodate the low second peak indicated by the data. Here we construct causal scaling seed models which reproduce the first and second peak. Future, more precise CMB anisotropy and polarization ex...

  16. Reionization and its imprint of the cosmic microwave background

    Science.gov (United States)

    Dodelson, Scott; Jubas, Jay M.

    1995-01-01

    Early reionization changes the pattern of anisotropies expected in the cosmic microwave backgrond. To explore these changes, we derive from first principles the equations governing anisotropies, focusing on the interactions of photons with electrons. Vishniac (1987) claimed that second-order terms can be large in a reionized universe, so we derive equations correct to second order in the perturbations. There are many more second-order terms than were considered by Vishniac. To understand the basic physics involved, we present a simple analytic approximation to the first-order equation. Then, turning to the second order equation, we show that the Vishniac term is indeed the only important one. We also present numerical results for a variety of ionization histories (in a standard cold dark matter universe) and show quantitatively how the signal in several experiments depends on the ionization history. The most pronounced indication of a reionized universe would be seen in very small scale experiments; the expected signal in the Owens Valley experiment is smaller by a factor of order 10 if the last scattering surface is at a redshift z approximately = 100 as it would be if the universe were reionized very early. On slightly larger scales, the expected signal in a reionized universe is smaller than it would be with standard recombination, but only a factor of 2 or so. The signal is even smaller in these experiments in the intermediate case where some photons last scattered at the standard recombination epoch.

  17. Cosmic Microwave Background Anisotropy Measurement From Python V

    CERN Document Server

    Coble, K; Dragovan, M; Ganga, K; Knox, L; Kovács, J; Ratra, B; Souradeep, T

    2003-01-01

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

  18. Occupational cosmic radiation exposure and cancer in airline cabin crew.

    Energy Technology Data Exchange (ETDEWEB)

    Kojo, K.

    2013-03-15

    Cosmic radiation dose rates are considerably higher at cruising altitudes of airplanes than at ground level. Previous studies have found increased risk of certain cancers among aircraft cabin crew, but the results are not consistent across different studies. Despite individual cosmic radiation exposure assessment is important for evaluating the relation between cosmic radiation exposure and cancer risk, only few previous studies have tried to develop an exposure assessment method. The evidence for adverse health effects in aircrews due to ionizing radiation is inconclusive because quantitative dose estimates have not been used. No information on possible confounders has been collected. For an occupational group with an increased risk of certain cancers it is very important to assess if the risk is related to occupational exposure. The goal of this thesis was to develop two separate retrospective exposure assessment methods for occupational exposure to cosmic radiation. The methods included the assessment based on survey on flight histories and based on company flight timetables. Another goal was to describe the cancer incidence among aircraft cabin crew with a large cohort in four Nordic countries, i.e., Finland, Iceland, Norway, and Sweden. Also the contribution of occupational as well as non-occupational factors to breast and skin cancer risk among the cabin crew was studied with case-control studies. Using the survey method of cosmic radiation exposure assessment, the median annual radiation dose of Finnish airline cabin crew was 0.6 milliSievert (mSv) in the 1960s, 3.3 mSv in the 1970s, and 3.6 mSv in the 1980s. With the flight timetable method, the annual radiation dose increased with time being 0.7 mSv in the 1960 and 2.1 mSv in the 1995. With the survey method, the median career dose was 27.9 mSv and with the timetable method 20.8 mSv. These methods provide improved means for individual cosmic radiation exposure assessment compared to studies where cruder

  19. A relationship between galactic cosmic radiation and tree rings.

    Science.gov (United States)

    Dengel, Sigrid; Aeby, Dominik; Grace, John

    2009-11-01

    Here, we investigated the interannual variation in the growth rings formed by Sitka spruce (Picea sitchensis) trees in northern Britain (55 degrees N, 3 degrees W) over the period 1961-2005 in an attempt to disentangle the influence of atmospheric variables acting at different times of year. Annual growth rings, measured along the north radius of freshly cut (frozen) tree discs and climatological data recorded at an adjacent site were used in the study. Correlations were based on Pearson product-moment correlation coefficients between the annual growth anomaly and these climatic and atmospheric factors. Rather weak correlations between these variables and growth were found. However, there was a consistent and statistically significant relationship between growth of the trees and the flux density of galactic cosmic radiation. Moreover, there was an underlying periodicity in growth, with four minima since 1961, resembling the period cycle of galactic cosmic radiation. * We discuss the hypotheses that might explain this correlation: the tendency of galactic cosmic radiation to produce cloud condensation nuclei, which in turn increases the diffuse component of solar radiation, and thus increases the photosynthesis of the forest canopy.

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

    Science.gov (United States)

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

    2016-12-01

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

  1. CONCORD: comparison of cosmic radiation detectors in the radiation field at aviation altitudes

    OpenAIRE

    Meier Matthias M.; Trompier François; Ambrozova Iva; Kubancak Jan; Matthiä Daniel; Ploc Ondrej; Santen Nicole; Wirtz Michael

    2016-01-01

    Space weather can strongly affect the complex radiation field at aviation altitudes. The assessment of the corresponding radiation exposure of aircrew and passengers has been a challenging task as well as a legal obligation in the European Union for many years. The response of several radiation measuring instruments operated by different European research groups during joint measuring flights was investigated in the framework of the CONCORD (COmparisoN of COsmic Radiation Detectors) campaign ...

  2. Effects of microgravity and cosmic radiations on human T lymphocytes

    Directory of Open Access Journals (Sweden)

    P. Pippia

    2011-01-01

    Full Text Available In space living organisms, including cells, are affected by two new environmental conditions: microgravity and cosmic radiations. Several experiments in dedicated space missions and in simulated microgravity have shown that low gravity causes a dramatic depression of the mitogenic in vitro activation of T lymphocytes. The goal of this reserch was to determine in space (on board the International Space Station the ability of adherent monocytes to migrate, as well as to interact with T-cells. A reduced motility of the J-111 cells and changes in the structures of actin, tubulin and vinculin were observed. Moreover, we demonstrated that LFA-I/ICAM-I interactions occur in space and are dependent on activation time but show differences in number, arrangement and fluorescence intensity, depending on time and experimental conditions. In order to evaluate the effects of cosmic radiations on the gene expression in human T lymphocytes we exposed these cells to high quote cosmic radiation during two stratospheric balloon trans-mediterranean flights (BIRBA missions. The gene expression was analized by cDNA microarray hybridization technology. Activated T cells react to the ionizing stress by activating genes involved in cell cycle check-point, oxidative stress response, heat shock proteins production or by repressing denes involved in antigen recognition.

  3. Can galaxy clusters, type Ia supernovae and cosmic microwave background ruled out a class of modified gravity theories?

    CERN Document Server

    Holanda, R F L

    2016-01-01

    In this paper we study cosmological signatures of modified gravity theories that can be written as a coupling between a extra scalar field and the electromagnetic part of the usual Lagrangian for the matter fields. In these frameworks all the electromagnetic sector of the theory is affected and variations of fundamental constants, of the cosmic distance duality relation and of the evolution law of the cosmic microwave background radiation (CMB) are expected and are related each other. In order to search these variations we perform jointly analyses with angular diameter distances of galaxy clusters, luminosity distances of type Ia supernovae and $T_{CMB}(z)$ measurements. We obtain tight constraints with no indication of violation of the standard framework.

  4. Angular Anisotropies in the Cosmic Gamma-ray Background as a Probe of its Origin

    CERN Document Server

    Miniati, Francesco; Di Matteo, Tiziana

    2007-01-01

    Notwithstanding the advent of the Gamma-ray Large Area Telescope, theoretical models predict that a significant fraction of the cosmic gamma-ray background (CGB), at the 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 from a few tens of arcmin to several degree scales, together with complementary GLAST observations of gamma-ray emission from galaxy clusters and the blazars luminosity function, can discriminate between a background that originates from unresolved blazars or cosmic rays accelerated at structure formation shocks.

  5. Peaks in the Cosmic Microwave Background flat versus open models

    CERN Document Server

    Barreiro, R B; Martínez-González, E; Cayon, L; Silk, J; Silk, Joseph

    1996-01-01

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

  6. Evidence for Dark Energy from the Cosmic Microwave Background Alone Using the Atacama Cosmology Telescope Lensing Measurements

    Science.gov (United States)

    Sherwin, Blake D.; Dunkley, Joanna; Das, Sudeep; Appel, John W.; Bond, J. Richard; Carvalho, C. Sofia; Devlin, Mark J.; Duenner, Rolando; Essinger-Hileman, Thomas; Fowler, Joesph J.; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hincks, Adam D.; Hlozek, Renee; Hughes, John P.; Irwin, Kent D.; Klein, Jeff; Kosowsky, Arthur; Marriage, Tobias A.; Marsden, Danica; Moodley, Kavilan; Menanteau, Felipe; Niemack, Michael D.; Wollack, Ed.

    2011-01-01

    For the first time, measurements of the cosmic microwave background radiation (CMB) alone favor cosmologies with w = -1 dark energy over models without dark energy at a 3.2-sigma level. We demonstrate this by combining the CMB lensing deflection power spectrum from the Atacama Cosmology Telescope with temperature and polarization power spectra from the "Wilkinson Microwave Anisotropy Probe. The lensing data break the geometric degeneracy of different cosmological models with similar CMB temperature power spectra. Our CMB-only measurement of the dark energy density Omega(delta) confirms other measurements from supernovae, galaxy clusters and baryon acoustic oscillations, and demonstrates the power of CMB lensing as a new cosmological tool.

  7. The Cosmic Infrared Background Experiment (CIBER): the Narrow Band Spectrometer

    CERN Document Server

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

    2013-01-01

    We have developed a near-infrared spectrometer designed to measure the absolute intensity of the Solar 854.2 nm CaII Fraunhofer line, scattered by interplanetary dust, in the Zodiacal light spectrum. Based on the known equivalent line width in the Solar spectrum, this measurement can derive the Zodiacal brightness, testing models of the Zodiacal light based on morphology that are used to determine the extragalactic background light in absolute photometry measurements. The spectrometer is based on a simple high-resolution tipped filter placed in front of a compact camera with wide-field refractive optics to provide the large optical throughput and high sensitivity required for rocket-borne observations. We discuss the instrument requirements for an accurate measurement of the absolute Zodiacal light brightness, the measured laboratory characterization, and the instrument performance in flight.

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

    Science.gov (United States)

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

    1991-01-01

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

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

    Science.gov (United States)

    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.

  10. On the radiative and thermodynamic properties of the extragalactic far infrared background radiation using COBE FIRAS instrument data

    CERN Document Server

    Fisenko, Anatoliy I

    2014-01-01

    Using the explicit form of the function to describe the average spectrum of the extragalactic far infrared background (FIRB) radiation measured by the COBE FIRAS instrument in the 0.15 - 2.4 THz frequency interval, the radiative and thermodynamic properties, such as the total emissivity, total radiation power per unit area, total energy density, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume, pressure, enthalpy density, and internal energy density are calculated. The calculated value of the total intensity received in the 0.15 - 2.4 THz frequency interval is 13.6 nW m^-2 sr^-1, and comprises about 19.4 % of the total intensity expected from the energy released by stellar nucleosynthesis over cosmic history. The radiative and thermodynamic functions of the extragalactic far infrared background (FIRB) radiation are calculated at redshift z = 1.5.

  11. Cosmic variance in the nanohertz gravitational wave background

    CERN Document Server

    Roebber, Elinore; Holz, Daniel; Warren, Michael

    2015-01-01

    We use large N-body simulations and empirical scaling relations between dark matter halos, galaxies, and supermassive black holes to estimate the formation rates of supermassive black hole binaries and the resulting low-frequency stochastic gravitational wave background (GWB). We find this GWB to be relatively insensitive ($\\lesssim10\\%$) to cosmological parameters, with only slight variation between WMAP5 and Planck cosmologies. We find that uncertainty in the astrophysical scaling relations changes the amplitude of the GWB by a factor of $\\sim 2$. Current observational limits are already constraining this predicted range of models. We investigate the Poisson variance in the amplitude of the GWB for randomly-generated populations of supermassive black holes, finding a scatter of order unity per frequency bin below 10 nHz, and increasing to a factor of $\\sim 10$ near 100 nHz. This variance is a result of the rarity of the most massive binaries, which dominate the signal, and acts as a fundamental uncertainty ...

  12. Contribution of Lensed SCUBA Galaxies to the Cosmic Infrared Background

    Science.gov (United States)

    Zemcov, Michael; Blain, Andrew; Halpern, Mark; Levenson, Louis

    2010-09-01

    The surface density of submillimeter (sub-mm) galaxies as a function of flux, usually termed the source number counts, constrains models of the evolution of the density and luminosity of starburst galaxies. At the faint end of the distribution, direct detection and counting of galaxies are not possible. However, gravitational lensing by clusters of galaxies allows detection of sources which would otherwise be too dim to study. We have used the largest catalog of sub-mm-selected sources along the line of sight to galaxy clusters to estimate the faint end of the 850 μm number counts; integrating to S = 0.10 mJy, the equivalent flux density at 850 μm is νI ν = 0.24 ± 0.03 nW m-2 sr-1. This provides a lower limit to the extragalactic far-infrared background and is consistent with direct estimates of the full intensity from the FIRAS. The results presented here can help to guide strategies for upcoming surveys carried out with single-dish sub-mm instruments.

  13. Contribution of Lensed SCUBA Galaxies to the Cosmic Infrared Background

    CERN Document Server

    Zemcov, M; Halpern, M; Levenson, L

    2010-01-01

    The surface density of sub-millimeter galaxies as a function of flux, usually termed the source number counts, constrains models of the evolution of the density and luminosty of starburst galaxies. At the faint end of the distribution, direct detection and counting of galaxies is not possible. However, gravitational lensing by clusters of galaxies allows detection of sources which would otherwise be too dim to study. We have used the largest catalog of sub-mm-selected sources along the line of sight to galaxy clusters to estimate the faint end of the 850 micron number counts; the equivalent flux density at 850 microns is v I_v = 3.9 +/- 0.7 x 10^-10 W/m^2/sr. This provides a lower limit to the extragalactic far infrared background and is consistent with direct estimates of the full intensity from the FIRAS. The results presented here can help to guide strategies for upcoming surveys carried out with single dish sub-mm instruments.

  14. Radio-loud AGNs at high redshifts and the cosmic microwave background

    CERN Document Server

    Ghisellini, G; Tavecchio, F; Haardt, F; Sbarrato, T

    2013-01-01

    We discuss how the interaction between the electrons in a relativistic jet and the Cosmic Microwave Background (CMB) affects the observable properties of radio-loud AGN at early epochs. At high z the magnetic energy density in the radio lobes of powerful radio-loud quasars can be exceeded by the energy density of the CMB (because of its (1+z)^4 dependance). In this case, relativistic electrons cool preferentially by scattering off CMB photons, rather than by synchrotron. Thus, sources sharing the same intrinsic properties have different extended radio and X-ray luminosities when located at different z: more distant sources are less luminous in radio and more luminous in X-rays than their closer counterparts. Instead, in compact regions where the local magnetic field still exceeds the CMB in terms of energy density, synchrotron radiation would be unaffected by the presence of the CMB. Such regions include the compact inner jet and the so-called hot spots in the radio lobes. The decrease in radio luminosity is ...

  15. Analysis of the new INTEGRAL Earth observations to measure the cosmic X-ray background

    CERN Document Server

    Türler, M; Pavan, L; Ferrigno, C; Bordas, P

    2013-01-01

    A new series of Earth occultation observations has been started in 2012 to refine the determination of the cosmic X-ray background by the INTEGRAL mission. We show here that the new detector lightcurves in the 3 to 160 keV range differ from the ones obtained in 2006. Instead of the expected modulation induced by the passage of the Earth through the field of view of the JEM-X, IBIS/ISGRI and SPI instruments, we record unrelated variability on shorter timescales. We discuss the differences obtained with the datasets of 2006 and 2012 in view of the changes in pointing direction, spacecraft orbit and solar cycle phase. We conclude that the Earth occultation signal in 2012 is likely blended by radioactive decay resulting from the activation of the spacecraft when crossing the proton radiation belt at perigee passage. The observed variability, on the other hand, results most likely from the current solar maximum. In addition to a variable particle environment from inhomogeneities of the solar wind, we also find evi...

  16. A precise and accurate determination of the cosmic microwave background temperature at z=0.89

    CERN Document Server

    Muller, S; Black, J H; Curran, S J; Horellou, C; Aalto, S; Combes, F; Guelin, M; Henkel, C

    2012-01-01

    According to the Big Bang theory and as a consequence of adiabatic expansion of the Universe, the temperature of the cosmic microwave background (CMB) increases linearly with redshift. This relation is, however, poorly explored, and detection of any deviation would directly lead to (astro-)physics beyond the standard model. We aim at measuring the temperature of the CMB with an accuracy of a few percent at z=0.89 toward the molecular absorber in the galaxy lensing the quasar PKS1830-211. We adopt a Monte-Carlo Markov Chain approach, coupled with predictions from the non-LTE radiative transfer code RADEX, to solve the excitation of a set of various molecular species directly from their spectra. We determine Tcmb=5.08 pm 0.10 K at 68% confidence level. Our measurement is consistent with the value Tcmb=5.14 K predicted by the standard cosmological model with adiabatic expansion of the Universe. This is the most precise determination of Tcmb at z>0 to date.

  17. The optimisation, design and verification of feed horn structures for future Cosmic Microwave Background missions

    Science.gov (United States)

    McCarthy, Darragh; Trappe, Neil; Murphy, J. Anthony; O'Sullivan, Créidhe; Gradziel, Marcin; Doherty, Stephen; Huggard, Peter G.; Polegro, Arturo; van der Vorst, Maarten

    2016-05-01

    In order to investigate the origins of the Universe, it is necessary to carry out full sky surveys of the temperature and polarisation of the Cosmic Microwave Background (CMB) radiation, the remnant of the Big Bang. Missions such as COBE and Planck have previously mapped the CMB temperature, however in order to further constrain evolutionary and inflationary models, it is necessary to measure the polarisation of the CMB with greater accuracy and sensitivity than before. Missions undertaking such observations require large arrays of feed horn antennas to feed the detector arrays. Corrugated horns provide the best performance, however owing to the large number required (circa 5000 in the case of the proposed COrE+ mission), such horns are prohibitive in terms of thermal, mechanical and cost limitations. In this paper we consider the optimisation of an alternative smooth-walled piecewise conical profiled horn, using the mode-matching technique alongside a genetic algorithm. The technique is optimised to return a suitable design using efficient modelling software and standard desktop computing power. A design is presented showing a directional beam pattern and low levels of return loss, cross-polar power and sidelobes, as required by future CMB missions. This design is manufactured and the measured results compared with simulation, showing excellent agreement and meeting the required performance criteria. The optimisation process described here is robust and can be applied to many other applications where specific performance characteristics are required, with the user simply defining the beam requirements.

  18. Cosmic Radiation – A Legal and Medical Issue in Aviation

    Directory of Open Access Journals (Sweden)

    Nataša Tomić-Petrović

    2012-03-01

    Full Text Available Research into the effects of different effects of radiation on human health has only recently been brought to light while the events in Hiroshima and Nagasaki have revived the interest in the research into the effects of ionizing radiation on organisms. The man has to live with radiation regardless of the risk. Protection efficiency is related with proper understanding of dangers coming from radiation and radiological contamination and protection methods. Knowledge in radiation protection is an important tool in the battle for survival on our planet. Our public today still seems insufficiently informed when it comes to hazards brought about by natural sources of radiation. Based on the published results it seems that the cosmic radiation hazard to passengers in contemporary air transport is nonexistent. Nevertheless, for some air crew categories (frequent intercontinental flights it is possible that annual absorbed doses are quite close to the doses absorbed by workers handling radiation sources, even the possibility of exceeding the prescribed levels is not inconceivable.

  19. Planck early results. XVIII. The power spectrum of cosmic infrared background anisotropies

    DEFF Research Database (Denmark)

    Bucher, M.; Delabrouille, J.; Giraud-Héraud, Y.

    2011-01-01

    Using Planck maps of six regions of low Galactic dust emission with a total area of about 140 deg2, we determine the angular power spectra of cosmic infrared background (CIB) anisotropies from multipole = 200 to = 2000 at 217, 353, 545 and 857 GHz. We use 21-cm observations of Hi as a tracer of t...

  20. Planck 2013 results. XXX. Cosmic infrared background measurements and implications for star formation

    DEFF Research Database (Denmark)

    Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.

    2014-01-01

    We present new measurements of cosmic infrared background (CIB) anisotropies using Planck. Combining HFI data with IRAS, the angular auto-and cross-frequency power spectrum is measured from 143 to 3000 GHz, and the auto-bispectrum from 217 to 545 GHz. The total areas used to compute the CIB power...

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

    Science.gov (United States)

    Doran, Michael; Seljak, Uros; Zaldarriaga, Matias

    2010-07-01

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

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

    CERN Document Server

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

    2011-01-01

    The Cosmic Infrared Background Experiment (CIBER) is a suite of four instruments designed to study the near infrared (IR) background light from above the Earth's atmosphere. The instrument package comprises two imaging telescopes designed to characterize spatial anisotropy in the extragalactic IR background caused by cosmological structure during the epoch of reionization, a low resolution spectrometer to measure the absolute spectrum of the extragalactic IR background, and a narrow band spectrometer optimized to measure the absolute brightness of the Zodiacal light foreground. In this paper we describe the design and characterization of the CIBER payload. The detailed mechanical, cryogenic, and electrical design of the system are presented, including all system components common to the four instruments. We present the methods and equipment used to characterize the instruments before and after flight, and give a detailed description of CIBER's flight profile and configurations. CIBER is designed to be recover...

  3. Self-organization of cosmic radiation pressure instability

    Science.gov (United States)

    Hogan, Craig J.

    1991-01-01

    Under some circumstances the absorption of radiation momentum by an absorbing medium opens the possibility of a dynamical instability, sometimes called 'mock gravity'. Here, a simplified abstract model is studied in which the radiation source is assumed to remain spatially uniform, there is no reabsorption or reradiated light, and no forces other than radiative pressure act on the absorbing medium. It is shown that this model displays the unique feature of being not only unstable, but also self-organizing. The structure approaches a statistical dynamical steady state which is almost independent of initial conditions. In this saturated state the absorbers are concentrated in thin walls around empty bubbles; as the instability develops the big bubbles get bigger and the small ones get crushed and disappear. A linear analysis shows that to first order the thin walls are indeed stable structures. It is speculated that this instability may play a role in forming cosmic large-scale structure.

  4. Neutrino Background Flux from Sources of Ultrahigh-Energy Cosmic-Ray Nuclei

    CERN Document Server

    Murase, Kohta

    2010-01-01

    Motivated by Pierre Auger Observatory results favoring a heavy nuclear composition for ultrahigh-energy (UHE) cosmic rays, we investigate implications for the cumulative neutrino background. The requirement that nuclei not be photodisintegrated constrains their interactions in sources, therefore limiting neutrino production via photomeson interactions. Assuming a $dN_{\\rm CR}/dE_{\\rm CR} \\propto E_{\\rm CR}^{-2}$ injection spectrum and photodisintegration via the giant dipole resonance, the background flux of neutrinos is lower than $E_\

  5. Hazards of cosmic radiation; Radiation cosmique: danger dans l'espace

    Energy Technology Data Exchange (ETDEWEB)

    Bonnet-Bidaud, J.M.; Dzitko, H

    2000-06-01

    The main limitations on long-distance space transport is neither the energy source nor the propulsion system but appears to be the protection of cosmonauts from radiation. Cosmic radiation is made up of protons (87%), alpha particles (12%) and heavy nuclei (1%), all these particles travel through interstellar space and come from the explosion of stars at the end of their life. The earth is protected from cosmic radiation by 3 natural shields: (i) the magnetic field generated by the solar wind, (ii) the earth magnetic field (magnetosphere), and (iii) the earth atmosphere, this elusive layer of air is equivalent to a 10 meter-high volume of water. Magnetosphere and atmosphere reduce the radiation dose by a factor 4000. According to a European directive (1996) air crews must be considered as radiation workers. (A.C.)

  6. Reproducing the observed Cosmic microwave background anisotropies with causal scaling seeds

    CERN Document Server

    Durrer, R; Melchiorri, A; Durrer, {R.

    2001-01-01

    During the last years it has become clear that global O(N) defects and U(1) cosmic strings do not lead to the pronounced first acoustic peak in the power spectrum of anisotropies of the cosmic microwave background which has recently been observed to high accuracy. Inflationary models cannot easily accommodate the low second peak indicated by the data. Here we construct causal scaling seed models which reproduce the first and second peak. Future, more precise CMB anisotropy and polarization experiments will however be able to distinguish them from the ordinary adiabatic models.

  7. 21-cm lensing and the cold spot in the cosmic microwave background.

    Science.gov (United States)

    Kovetz, Ely D; Kamionkowski, Marc

    2013-04-26

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

  8. Thermodynamic properties of neutral particle in presence of Topological defects in Magnetic Cosmic String Background

    CERN Document Server

    Hassanabadi, Hassan

    2016-01-01

    In this paper, we study the covariant form of the non-relativistic Schrodinger-Pauli equation in the space-time generated by a cosmic string and discuss the solutions of this equation in present of interaction between the magnetic dipole momentum and electromagnetic field. We study the influence of the topology on this system. We obtain the solution of radial part as well as the energy levels. We consider all thermodynamic properties of neutral particle in magnetic cosmic string background by using an approach based on the partition function method.

  9. Thermodynamic properties of neutral particle in the presence of topological defects in magnetic cosmic string background

    Energy Technology Data Exchange (ETDEWEB)

    Hassanabadi, H.; Hosseinpour, M. [Shahrood University of Technology, Physics Department, Shahrood (Iran, Islamic Republic of)

    2016-10-15

    In this paper, we study the covariant form of the non-relativistic Schroedinger-Pauli equation in the space-time generated by a cosmic string and discuss the solutions of this equation in the presence of interaction between the magnetic dipole momentum and electromagnetic field. We study the influence of the topology on this system. We obtain the solution of radial part as well as the energy levels. We consider all thermodynamic properties of a neutral particle in a magnetic cosmic string background by using an approach based on the partition function method. (orig.)

  10. The cosmic MeV neutrino background as a laboratory for black hole formation

    Directory of Open Access Journals (Sweden)

    Hasan Yüksel

    2015-12-01

    Full Text Available Calculations of the cosmic rate of core collapses, and the associated neutrino flux, commonly assume that a fixed fraction of massive stars collapse to black holes. We argue that recent results suggest that this fraction instead increases with redshift. With relatively more stars vanishing as “unnovae” in the distant universe, the detectability of the cosmic MeV neutrino background is improved due to their hotter neutrino spectrum, and expectations for supernova surveys are reduced. We conclude that neutrino detectors, after the flux from normal SNe is isolated via either improved modeling or the next Galactic SN, can probe the conditions and history of black hole formation.

  11. Experimental study of variations in background radiation and the effect on Nuclear Car Wash sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Church, J; Slaughter, D; Norman, E; Asztalos, S; Biltoft, P

    2007-02-07

    Error rates in a cargo screening system such as the Nuclear Car Wash [1-7] depend on the standard deviation of the background radiation count rate. Because the Nuclear Car Wash is an active interrogation technique, the radiation signal for fissile material must be detected above a background count rate consisting of cosmic, ambient, and neutron-activated radiations. It was suggested previously [1,6] that the Corresponding negative repercussions for the sensitivity of the system were shown. Therefore, to assure the most accurate estimation of the variation, experiments have been performed to quantify components of the actual variance in the background count rate, including variations in generator power, irradiation time, and container contents. The background variance is determined by these experiments to be a factor of 2 smaller than values assumed in previous analyses, resulting in substantially improved projections of system performance for the Nuclear Car Wash.

  12. Computation of cosmic radiation spectra and application to aircrew dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Song Jae

    2002-02-15

    Using the Monte Carlo radiation transport code FLUKA- 99, secondary cosmic radiation energy spectra and intensities of neutrons, protons, photons, electrons, and muons were calculated for different geographical latitude and longitude at the commercial jet's altitudes ranging from 27000 ft to 41000 ft. The Badhwar's proton model was used to construct the primary cosmic radiation spectrum and effect of the vertical cutoff rigidity was considered after spectra similar to those given in literature were resulted. By applying the effective dose conversion factors, a calculation tool for aircrew doses was developed. According to the resulting dose rate distribution, effective dose rate over North pole region is around three times of that over equator region due to the geomagnetical shielding effect. Illustrative assessments of aircrew doses were made for four distinctive routes of Korean airliners : Seoul - New York (USA), London (UK), Sydney (Australia) and Mumbai(India). The effective doses to aircrew incurred from a round trip were 0.047, 0.055, 0.018, and 0.018{mu}Sv, respectively. If aircrew work 500 hour s a year at the cruise altitude of a international airline, the individual dose would reach 2 mSv which is about the same size as the average annual dose of workers at a nuclear power plant.

  13. Tests for Gaussianity of the MAXIMA-1 cosmic microwave background map.

    Science.gov (United States)

    Wu, J H; Balbi, A; Borrill, J; Ferreira, P G; Hanany, S; Jaffe, A H; Lee, A T; Rabii, B; Richards, P L; Smoot, G F; Stompor, R; Winant, C D

    2001-12-17

    Gaussianity of the cosmological perturbations is one of the key predictions of standard inflation, but it is violated by other models of structure formation such as cosmic defects. We present the first test of the Gaussianity of the cosmic microwave background (CMB) on subdegree angular scales, where deviations from Gaussianity are most likely to occur. We apply the methods of moments, cumulants, the Kolmogorov test, the chi(2) test, and Minkowski functionals in eigen, real, Wiener-filtered, and signal-whitened spaces, to the MAXIMA-1 CMB anisotropy data. We find that the data, which probe angular scales between 10 arcmin and 5 deg, are consistent with Gaussianity. These results show consistency with the standard inflation and place constraints on the existence of cosmic defects.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bersanelli, S.; Bonelli, G.; Sironi, G. (Universita degli Studi, Milan (Italy)); Levin, S. (California Institute of Technology, Pasadena, CA (United States)); Smoot, G.F.; Bensadoun, M.; De Amici, G.; Limon, M.; Vinje, W. (Lawrence Berkeley Lab., CA (United States))

    1993-01-01

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

  15. Cosmic-ray induced background intercomparison with actively shielded HPGe detectors at underground locations

    CERN Document Server

    Szücs, T; Reinhardt, T P; Schmidt, K; Takács, M P; Wagner, A; Wagner, L; Weinberger, D; Zuber, K

    2015-01-01

    The main background above 3\\,MeV for in-beam nuclear astrophysics studies with $\\gamma$-ray detectors is caused by cosmic-ray induced secondaries. The two commonly used suppression methods, active and passive shielding, against this kind of background were formerly considered only as alternatives in nuclear astrophysics experiments. In this work the study of the effects of active shielding against cosmic-ray induced events at a medium deep location is performed. Background spectra were recorded with two actively shielded HPGe detectors. The experiment was located at 148\\,m below the surface of the Earth in the Reiche Zeche mine in Freiberg, Germany. The results are compared to data with the same detectors at the Earth's surface, and at depths of 45\\,m and 1400\\,m, respectively.

  16. Cyanogen Excitation Measurements of the Cosmic Microwave Background Temperature at 2.64 mm

    Science.gov (United States)

    Roth, K. C.; Meyer, D. M.

    1993-01-01

    We have measured CN excitation temperatures in the diffuse lines of sight toward the stars zeta Ophiuchi, zeta Persei, HD 27778, HD 21483 and HD 154368. We find respective 2.64 mm rotational excitation temperatures of 2.737 +/- 0.025, 2.774 +/- 0.086, 2.769 +/- (0.093}_{0.099), 2.771 +/- (0.057}_{0.060) and 2.68 +/- (0.22}_{0.33)K. The fact that these values are all consistent with each other even though the associated CN column densities range over an order of magnitude strongly suggests that local processes contribute little to the excitation. We have corrected our temperatures for the small local collisional effects utilizing millimeter searches for CN line emission. The resulting values give a weighted average temperature for the cosmic microwave background radiation (CMBR) at 2.64 mm of 2.733 +/- (0.023}_{0.031)K. We also find a CMBR temperature at 1.32 mm of 2.657 +/- 0.057 K. Our result is entirely consistent with the CMBR temperature results from COBE (Mather et al. 1990, Ap.J. 354, L37) and the COBRA rocket experiment (Gush, Halpern and Wishnow 1990, Phys. Rev. Lett. 65, 537) of 2.735 +/- 0.06 and 2.736 +/- 0.017 K, respectively. CN excitation determinations are not susceptible to the same systematic errors as are the direct measurement experiments. In addition, our temperatures originate in physically separate Galactic locations far from the near-Earth environment. The excellent agreement among the results from these independent methods attests to the accuracy of each approach and reaffirms the global nature of the background radiation. Our measurements stem from a large set of observations utilizing CCD detectors with various telescope and instrument combinations. The data were analyzed in a consistent manner designed to expose systematic equivalent width measurement errors resulting from the different instrumental configurations. We have found no evidence for such a bias and feel this illustrates the potential for using CCD detectors in sensitive

  17. measurement of indoor background ionizing radiation in some

    African Journals Online (AJOL)

    Administrator

    ABSTRACT. Certain types of building materials are known to be radioactive. ... Indoor background ionizing radiation profiles for a building are ..... Survey of Radiation Levels during. Radiological Examinations in some selected Hospitals in Jos,.

  18. Gravitational Instability in Radiation Pressure Dominated Backgrounds

    CERN Document Server

    Thompson, Todd A

    2008-01-01

    I consider the physics of gravitational instabilities in the presence of dynamically important radiation pressure and gray radiative diffusion, governed by a constant opacity, kappa. For any non-zero radiation diffusion rate on an optically-thick scale, the medium is unstable unless the classical gas-only isothermal Jeans criterion is satisfied. When diffusion is "slow," although the dynamical Jeans instability is stabilized by radiation pressure on scales smaller than the adiabatic Jeans length, on these same spatial scales the medium is unstable to a diffusive mode. In this regime, neglecting gas pressure, the characteristic timescale for growth is independent of spatial scale and given by (3 kappa c_s^2)/(4 pi G c), where c_s is the adiabatic sound speed. This timescale is that required for a fluid parcel to radiate away its thermal energy content at the Eddington limit, the Kelvin-Helmholz timescale for a radiation pressure supported self-gravitating object. In the limit of "rapid" diffusion, radiation do...

  19. A search for the large angular scale polarization of the cosmic microwave background

    Science.gov (United States)

    Keating, Brian Gregory

    The Cosmic Microwave Background (CMB) is one of the three observational pillars of modern cosmology, along with the Hubble Expansion Law and the measured abundances of the light elements. Being the fossil radiation from the Big Bang, it probes the conditions of the early universe. Three properties are necessary to fully characterize the CMB: its spectrum, spatial isotropy, and polarization. The first two properties have been measured, whereas the polarization state of the CMB remains undetected. Detection of, or an improved upper limit on, the polarization of the CMB at large scales holds great promise for the determination of several fundamental properties of the standard cosmological model, such as the ionization history of the Universe and the contribution of gravitational waves to the spectrum of primordial perturbations. Most models predict that the magnitude of the polarization of the CMB at large angular scales is less than 1muK. This is at least an order of magnitude below both the large scale anisotropy level of the CMB, as well as the best existing upper limits on its polarization. In this thesis I calculate the magnitude of the CMB polarization in various cosmological scenarios, and outline the fundamental challenges to measuring these signals. Following, I describe the design of the POLAR Polarization Observations of Large Angular Regions) experiment, which is the first dedicated polarimeter to study the CMB in more than a decade. POLAR is a ground-based, centimeter-wavelength correlation polarimeter designed to detect the polarization of the CMB at 28, 31, & 33 GHz. POLAR is the first correlation polarimeter ever used for CMB work and has the widest bandwidth of any correlation radiometer ever used for investigations of the CMB. POLAR has been constructed and is currently acquiring data at the University of Wisconsin-Madison.

  20. General Constraints on Dark Matter Decay from the Cosmic Microwave Background

    CERN Document Server

    Slatyer, Tracy R

    2016-01-01

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

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

    Science.gov (United States)

    Chuss, David T.

    2011-01-01

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

  2. The Spectrum of the Cosmic Microwave Background Anisotropy from the Combined COBE FIRAS and WMAP Observations

    Science.gov (United States)

    Fixsen, D. J.

    2003-09-01

    The cosmic microwave background (CMB) anisotropy data from the COBE Far Infrared Absolute Spectrophotometer (FIRAS) is reanalyzed in light of the Wilkinson Microwave Anisotropy Probe (WMAP) observations. The frequency spectrum of the FIRAS signal that has the spatial distribution seen by WMAP is shown to be consistent with CMB temperature fluctuations well into the Wien region of the spectrum. The consistency of these data, from very different instruments with very different observing strategies, provides compelling support for the interpretation that the signal seen by WMAP is temperature anisotropy of cosmological origin. The data also limit rms fluctuations in the Compton y parameter, observable via the Sunyaev-Zeldovich effect, to Δy<3×10-6 (95% confidence level) on ~5° angular scales. The National Aeronautics and Space Administration Goddard Space Flight Center (NASA/GSFC) was responsible for the design, development, and operation of the Cosmic Background Explorer (COBE).

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

    Science.gov (United States)

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

    2012-06-01

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

  4. Improved Measurements of the Temperature and Polarization of the Cosmic Microwave Background from QUaD

    OpenAIRE

    Brown, M L; Ade, P.; Bock, J.; Bowden, M.; Cahill, G.; Castro, P.G. (Patricia Garrido); Church, S.; Culverhouse, T.; Friedman, R. B.; Ganga, K.; Gear, W.K.; S. Gupta; Hinderks, J.; Kovac, John M.; Lange, A. E.

    2009-01-01

    We present an improved analysis of the final data set from the QUaD experiment. Using an improved technique to remove ground contamination, we double the effective sky area and hence increase the precision of our cosmic microwave background (CMB) power spectrum measurements by ~30% versus that previously reported. In addition, we have improved our modeling of the instrument beams and have reduced our absolute calibration uncertainty from 5% to 3.5% in temperature. The robustness of our result...

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

    Science.gov (United States)

    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 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 detailed designs of the mechanical, cryogenic, and electrical systems. Plans for the future will also be presented.

  6. The {ital COBE} Diffuse Infrared Background Experiment Search for the Cosmic Infrared Background. I. Limits and Detections

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, M.G. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Arendt, R.G. [Raytheon STX, Code 685, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kelsall, T.; Dwek, E. [Code 685, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Odegard, N.; Weiland, J.L.; Freudenreich, H.T. [Raytheon STX, Code 685, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Reach, W.T. [California Institute of Technology, IPAC/JPL, MS 100-22, Pasadena, CA 91125 (United States); Silverberg, R.F.; Moseley, S.H. [Code 685, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Pei, Y.C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Lubin, P. [Physics Department, University of California at Santa Barbara, Santa Barbara, CA 93106 (United States); Mather, J.C.; Shafer, R.A. [Code 685, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Smoot, G.F. [Lawrence Berkeley Laboratory, Space Sciences Laboratory, Department of Physics, UC Berkeley, CA 94720 (United States); Weiss, R. [Massachusetts Institute of Technology, Room 20F-001, Department of Physics, Cambridge, MA 02139 (United States); Wilkinson, D.T. [Princeton University, Department of Physics, Jadwin Hall, Box 708, Princeton, NJ 08544 (United States); Wright, E.L. [UCLA, Astronomy Department, Los Angeles, CA 90024-1562 (United States)

    1998-11-01

    The Diffuse Infrared Background Experiment (DIRBE) on the Cosmic Background Explorer ({ital COBE}) spacecraft was designed primarily to conduct a systematic search for an isotropic cosmic infrared background (CIB) in 10 photometric bands from 1.25 to 240 {mu}m. The results of that search are presented here. Conservative limits on the CIB are obtained from the minimum observed brightness in all-sky maps at each wavelength, with the faintest limits in the DIRBE spectral range being at 3.5 {mu}m ({nu}{ital I}{sub {nu}} {lt} 64 nW m{sup {minus}2} sr{sup {minus}1}, 95{percent} confidence level) and at 240 {mu}m ({nu}{ital I}{sub {nu}} {lt} 28 nW m{sup {minus}2} sr{sup {minus}1}, 95{percent} confidence level). The bright foregrounds from interplanetary dust scattering and emission, stars, and interstellar dust emission are the principal impediments to the DIRBE measurements of the CIB. These foregrounds have been modeled and removed from the sky maps. Assessment of the random and systematic uncertainties in the residuals and tests for isotropy show that only the 140 and 240 {mu}m data provide candidate detections of the CIB. The residuals and their uncertainties provide CIB upper limits more restrictive than the dark sky limits at wavelengths from 1.25 to 100 {mu}m. No plausible solar system or Galactic source of the observed 140 and 240 {mu}m residuals can be identified, leading to the conclusion that the CIB has been detected at levels of {nu}{ital I}{sub {nu}} = 25 {plus_minus} 7 and 14 {plus_minus} 3 nW m{sup {minus}2} sr{sup {minus}1} at 140 and 240 {mu}m, respectively. The integrated energy from 140 to 240 {mu}m, 10.3 nW m{sup {minus}2} sr{sup {minus}1}, is about twice the integrated optical light from the galaxies in the Hubble Deep Field, suggesting that star formation might have been heavily enshrouded by dust at high redshift. The detections and upper limits reported here provide new constraints on models of the history of energy-releasing processes and dust

  7. New Measurements of the Cosmic Background Radiation Spectrum

    Science.gov (United States)

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

    We continue consideration of ways-and-means for creating, in an evolutionary, ever-more-powerful manner, a continually-updated data-base of salient atmospheric properties sufficient for finite differenced integration-based, high-fidelity weather prediction over intervals of 2-3 weeks, leveraging the 10{sup 14} FLOPS digital computing systems now coming into existence. A constellation comprised of 10{sup 6}-10{sup 9} small atmospheric sampling systems--high-tech superpressure balloons carrying early 21st century semiconductor devices, drifting with the local winds over the meteorological spectrum of pressure-altitudes--that assays all portions of the troposphere and lower stratosphere remains the central feature of the proposed system. We suggest that these devices should be active-signaling, rather than passive-transponding, as we had previously proposed only for the ground- and aquatic-situated sensors of this system. Instead of periodic interrogation of the intra-atmospheric transponder population by a constellation of sophisticated small satellites in low Earth orbit, we now propose to retrieve information from the instrumented balloon constellation by existing satellite telephony systems, acting as cellular tower-nodes in a global cellular telephony system whose ''user-set'' is the atmospheric-sampling and surface-level monitoring constellations. We thereby leverage the huge investment in cellular (satellite) telephony and GPS technologies, with large technical and economic gains. This proposal minimizes sponsor forward commitment along its entire programmatic trajectory, and moreover may return data of weather-predictive value soon after field activities commence. We emphasize its high near-term value for making better mesoscale, relatively short-term weather predictions with computing-intensive means, and its great long-term utility in enhancing the meteorological basis for global change predictive studies. We again note that adverse impacts of weather involve continuing costs of the order of 1% of GDP, a large fraction of which could be retrieved if high-fidelity predictions of two weeks forward applicability were available. These{approx}$10{sup 2} B annual savings dwarf the<$1 B costs of operating a rational, long-range weather prediction system of the type proposed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Atrio-Barandela, F. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kashlinsky, A., E-mail: atrio@usal.es, E-mail: Alexander.Kashlinsky@nasa.gov [Observational Cosmology Lab, NASA Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States)

    2014-12-20

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

  9. Probing the epoch of pre-reionization by cross-correlating cosmic microwave and infrared background anisotropies

    CERN Document Server

    Atrio-Barandela, Fernando

    2014-01-01

    The epoch of first star formation and the state of the intergalactic medium (IGM) at that time are not directly observable with current telescopes. The radiation from those early sources is now part of the Cosmic Infrared Background (CIB) and, as these sources ionize the gas around them, the IGM plasma would produce faint temperature anisotropies in the Cosmic Microwave Background (CMB) via the thermal Sunyaev-Zeldovich (TSZ) effect. While these TSZ anisotropies are too faint to be detected, we show that the cross-correlation of maps of source-subtracted CIB fluctuations from {\\it Euclid}, with suitably constructed microwave maps at different frequencies can probe the physical state of the gas during reionization and test/constrain models of the early CIB sources. We identify the frequency-combined CMB-subtracted microwave maps from space and ground-based instruments to show that they can be cross-correlated with the forthcoming all-sky {\\it Euclid} CIB maps to detect the cross-power at scales $\\sim 5'-60'$ w...

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

    Science.gov (United States)

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

    2016-08-01

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

  11. The REPAIR Project: Examining the Biological Impacts of Sub-Background Radiation Exposure within SNOLAB, a Deep Underground Laboratory.

    Science.gov (United States)

    Thome, Christopher; Tharmalingam, Sujeenthar; Pirkkanen, Jake; Zarnke, Andrew; Laframboise, Taylor; Boreham, Douglas R

    2017-07-19

    Considerable attention has been given to understanding the biological effects of low-dose ionizing radiation exposure at levels slightly above background. However, relatively few studies have been performed to examine the inverse, where natural background radiation is removed. The limited available data suggest that organisms exposed to sub-background radiation environments undergo reduced growth and an impaired capacity to repair genetic damage. Shielding from background radiation is inherently difficult due to high-energy cosmic radiation. SNOLAB, located in Sudbury, Ontario, Canada, is a unique facility for examining the effects of sub-background radiation exposure. Originally constructed for astroparticle physics research, the laboratory is located within an active nickel mine at a depth of over 2,000 m. The rock overburden provides shielding equivalent to 6,000 m of water, thereby almost completely eliminating cosmic radiation. Additional features of the facility help to reduce radiological contamination from the surrounding rock. We are currently establishing a biological research program within SNOLAB: Researching the Effects of the Presence and Absence of Ionizing Radiation (REPAIR project). We hypothesize that natural background radiation is essential for life and maintains genomic stability, and that prolonged exposure to sub-background radiation environments will be detrimental to biological systems. Using a combination of whole organism and cell culture model systems, the effects of exposure to a sub-background environment will be examined on growth and development, as well as markers of genomic damage, DNA repair capacity and oxidative stress. The results of this research will provide further insight into the biological effects of low-dose radiation exposure as well as elucidate some of the processes that may drive evolution and selection in living systems. This Radiation Research focus issue contains reviews and original articles, which relate to the

  12. Lyman α radiation hydrodynamics of galactic winds before cosmic reionization

    Science.gov (United States)

    Smith, Aaron; Bromm, Volker; Loeb, Abraham

    2017-01-01

    The dynamical impact of Lyman α (Lyα) radiation pressure on galaxy formation depends on the rate and duration of momentum transfer between Lyα photons and neutral hydrogen gas. Although photon trapping has the potential to multiply the effective force, ionizing radiation from stellar sources may relieve the Lyα pressure before appreciably affecting the kinematics of the host galaxy or efficiently coupling Lyα photons to the outflow. We present self-consistent Lyα radiation-hydrodynamics simulations of high-z galaxy environments by coupling the Cosmic Lyα Transfer code (COLT) with spherically symmetric Lagrangian frame hydrodynamics. The accurate but computationally expensive Monte Carlo radiative transfer calculations are feasible under the one-dimensional approximation. The initial starburst drives an expanding shell of gas from the centre and in certain cases, Lyα feedback significantly enhances the shell velocity. Radiative feedback alone is capable of ejecting baryons into the intergalactic medium (IGM) for protogalaxies with a virial mass of Mvir ≲ 108 M⊙. We compare the Lyα signatures of Population III stars with 105 K blackbody emission to that of direct collapse black holes with a non-thermal Compton-thick spectrum and find substantial differences if the Lyα spectra are shaped by gas pushed by Lyα radiation-driven winds. For both sources, the flux emerging from the galaxy is reprocessed by the IGM such that the observed Lyα luminosity is reduced significantly and the time-averaged velocity offset of the Lyα peak is shifted redward.

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

    Science.gov (United States)

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

    2017-06-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Wei-Ming; Cai, Rong-Gen [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China); University of Chinese Academy of Sciences, School of Physical Sciences, Beijing (China); Guo, Zong-Kuan [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China); University of Chinese Academy of Sciences, School of Astronomy and Space Science, Beijing (China); Zhang, Yuan-Zhong [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China)

    2017-06-15

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

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

    Science.gov (United States)

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

    2011-01-01

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

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

    Science.gov (United States)

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

    2013-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Zemcov, M.; Bock, J.; Hristov, V.; Levenson, L. R.; Mason, P. [Department of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Arai, T.; Matsumoto, T.; Matsuura, S.; Tsumura, K.; Wada, T. [Department of Space Astronomy and Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa 252-5210 (Japan); Battle, J. [Jet Propulsion Laboratory (JPL), National Aeronautics and Space Administration (NASA), Pasadena, CA 91109 (United States); Cooray, A. [Center for Cosmology, University of California, Irvine, Irvine, CA 92697 (United States); Keating, B.; Renbarger, T. [Department of Physics, University of California, San Diego, San Diego, CA 92093 (United States); Kim, M. G. [Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, D. H.; Nam, U. W. [Korea Astronomy and Space Science Institute (KASI), Daejeon 305-348 (Korea, Republic of); Sullivan, I. [Department of Physics, The University of Washington, Seattle, WA 98195 (United States); Suzuki, K., E-mail: zemcov@caltech.edu [Instrument Development Group of Technical Center, Nagoya University, Nagoya, Aichi 464-8602 (Japan)

    2013-08-15

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

  18. Alteration of Organic Compounds in Small Bodies and Cosmic Dusts by Cosmic Rays and Solar Radiation

    Science.gov (United States)

    Kobayashi, Kensei; Kaneko, Takeo; Mita, Hajime; Obayashi, Yumiko; Takahashi, Jun-ichi; Sarker, Palash K.; Kawamoto, Yukinori; Okabe, Takuto; Eto, Midori; Kanda, Kazuhiro

    2012-07-01

    A wide variety of complex organic compounds have been detected in extraterrestrial bodies like carbonaceous chondrites and comets, and their roles in the generation of terrestrial life are discussed. It was suggested that organics in small bodies were originally formed in ice mantles of interstellar dusts in dense cloud. Irradiation of frozen mixture of possible interstellar molecules including CO (or CH _{3}OH), NH _{3} and H _{2}O with high-energy particles gave complex amino acid precursors with high molecular weights [1]. Such complex organic molecules were taken in planetesimals or comets in the early solar system. In prior to the generation of the terrestrial life, extraterrestrial organics were delivered to the primitive Earth by such small bodies as meteorites, comets and space dusts. These organics would have been altered by cosmic rays and solar radiation (UV, X-rays) before the delivery to the Earth. We examined possible alteration of amino acids, their precursors and nucleic acid bases in interplanetary space by irradiation with high energy photons and heavy ions. A mixture of CO, NH _{3} and H _{2}O was irradiated with high-energy protons from a van de Graaff accelerator (TIT, Japan). The resulting products (hereafter referred to as CAW) are complex precursors of amino acids. CAW, amino acids (dl-Isovaline, glycine), hydantoins (amino acid precursors) and nucleic acid bases were irradiated with continuous emission (soft X-rays to IR; hereafter referred to as soft X-rays irradiation) from BL-6 of NewSUBARU synchrotron radiation facility (Univ. Hyogo). They were also irradiated with heavy ions (eg., 290 MeV/u C ^{6+}) from HIMAC accelerator (NIRS, Japan). After soft X-rays irradiation, water insoluble materials were formed. After irradiation with soft X-rays or heavy ions, amino acid precursors (CAW and hydantoins) gave higher ratio of amino acids were recovered after hydrolysis than free amino acids. Nucleic acid bases showed higher stability than free

  19. Galactic cosmic ray induced radiation dose on terrestrial exoplanets

    CERN Document Server

    Atri, Dimitra; Griessmeier, Jean-Mathias

    2013-01-01

    This past decade has seen tremendous advancements in the study of extrasolar planets. Observations are now made with increasing sophistication from both ground and space based instruments, and exoplanets are characterized with increasing precision. There is a class of particularly interesting exoplanets, falling in the habitable zone, which is defined as the area around a star where the planet is capable of supporting liquid water on its surface. Theoretical calculations also suggest that close-in exoplanets are more likely to have weaker planetary magnetic fields, especially in case of super earths. Such exoplanets are subjected to a high flux of Galactic Cosmic Rays (GCRs) due to their weak magnetic moments. GCRs are energetic particles of astrophysical origin, which strike the planetary atmosphere and produce secondary particles, including muons, which are highly penetrating. Some of these particles reach the planetary surface and contribute to the radiation dose. Along with the magnetic field, another fac...

  20. Comparative Measurements of Cosmic Radiation Monitors for Aircrew Exposure Assessment

    Science.gov (United States)

    Getley, I. L.; Bennett, L. G. I.; Boudreau, M. L.; Lewis, B. J.; Green, A. R.; Butler, A.; Takada, M.; Nakamura, T.

    Various commercially available electronic personal dosimeters (EPDs) have recently been flown on numerous scheduled airline flights in order to determine their viability as small, convenient monitors to measure cosmic radiation at altitude. Often, frequent flyers or airline crew will acquire such dosimeters and report the readings from their flights, without due regard for the mixed radiation field at altitude, which is different from the intended fields on land. A sampling of EPDs has been compared to two types of spectrometers, which measure the total radiation spectrum. The "HAWK" tissue equivalent proportional counter is considered a reference instrument and measures the total dose equivalent H*(10). The Liulin-4N and 4SN linear energy transfer spectrometers each have a silicon semiconductor-based PIN diode detector which provides an absorbed dose, D, but have been further developed to provide H*(10). A Thermo Electron FH41B and B-10, and EPD-N2, and several personal dosimeters (Fuji NRY-21 and NRF-20, and RADOS DIS-100) were also flown.

  1. Thick Galactic Cosmic Radiation Shielding Using Atmospheric Data

    Science.gov (United States)

    Youngquist, Robert C.; Nurge, Mark A.; Starr, Stanley O.; Koontz, Steven L.

    2013-01-01

    NASA is concerned with protecting astronauts from the effects of galactic cosmic radiation and has expended substantial effort in the development of computer models to predict the shielding obtained from various materials. However, these models were only developed for shields up to about 120 g!cm2 in thickness and have predicted that shields of this thickness are insufficient to provide adequate protection for extended deep space flights. Consequently, effort is underway to extend the range of these models to thicker shields and experimental data is required to help confirm the resulting code. In this paper empirically obtained effective dose measurements from aircraft flights in the atmosphere are used to obtain the radiation shielding function of the earth's atmosphere, a very thick shield. Obtaining this result required solving an inverse problem and the method for solving it is presented. The results are shown to be in agreement with current code in the ranges where they overlap. These results are then checked and used to predict the radiation dosage under thick shields such as planetary regolith and the atmosphere of Venus.

  2. Comparative Measurements of Cosmic Radiation Monitors for Aircrew Exposure Assessment

    Science.gov (United States)

    Getley, I. L.; Bennett, L. G. I.; Boudreau, M. L.; Lewis, B. J.; Green, A. R.; Butler, A.; Takada, M.; Nakamura, T.

    Various commercially available electronic personal dosimeters (EPDs) have recently been flown on numerous scheduled airline flights in order to determine their viability as small, convenient monitors to measure cosmic radiation at altitude. Often, frequent flyers or airline crew will acquire such dosimeters and report the readings from their flights, without due regard for the mixed radiation field at altitude, which is different from the intended fields on land. A sampling of EPDs has been compared to two types of spectrometers, which measure the total radiation spectrum. The “HAWK” tissue equivalent proportional counter is considered a reference instrument and measures the total dose equivalent H * (10). The Liulin-4N and 4SN linear energy transfer spectrometers each have a silicon semiconductor-based PIN diode detector which provides an absorbed dose, D, but have been further developed to provide H * (10). A Thermo Electron FH41B and B-10, and EPD-N2, and several personal dosimeters (Fuji NRY-21 and NRF-20, and RADOS DIS-100) were also flown.

  3. The Origin of the Universe as Revealed Through the Polarization of the Cosmic Microwave Background

    CERN Document Server

    Dodelson, S; Hanany, S; McAllister, L; Meyer, S; Page, L; Ade, P; Amblard, A; Ashoorioon, A; Baccigalupi, C; Balbi, A; Bartlett, J; Bartolo, N; Baumann, D; Beltran, M; Benford, D; Birkinshaw, M; Bock, J; Bond, D; Borrill, J; Bouchet, F; Bridges, M; Bunn, E; Calabrese, E; Cantalupo, C; Caramete, A; Carbone, C; Carroll, S; Chatterjee, S; Chen, X; Church, S; Chuss, D; Contaldi, C; Cooray, A R; Creminelli, P; Das, S; De Bernardis, F; De Bernardis, P; Delabrouille, J; Desert, F -X; Devlin, M; Dickinson, C; Dicker, S; Di Pirro, M; Dobbs, M; Dore, O; Dotson, J; Dunkley, J; Dvorkin, C; Eriksen, H K; Falvella, M Cristina; Finley, D; Finkbeiner, D; Fixsen, D; Flauger, R; Fosalba, P; Fowler, J; Galli, S; Gates, E; Gear, W; Giraud-Héraud, Y; Gorski, K; Greene, B; Gruppuso, A

    2009-01-01

    Modern cosmology has sharpened questions posed for millennia about the origin of our cosmic habitat. The age-old questions have been transformed into two pressing issues primed for attack in the coming decade: How did the Universe begin? and What physical laws govern the Universe at the highest energies? The clearest window onto these questions is the pattern of polarization in the Cosmic Microwave Background (CMB), which is uniquely sensitive to primordial gravity waves. A detection of the special pattern produced by gravity waves would be not only an unprecedented discovery, but also a direct probe of physics at the earliest observable instants of our Universe. Experiments which map CMB polarization over the coming decade will lead us on our first steps towards answering these age-old questions.

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

    CERN Document Server

    Kamada, Ayuki; Takahashi, Tomo; Yoshida, Naoki

    2016-01-01

    We examine the possibility that dark matter (DM) consists of charged massive particles (CHAMPs) in view of the cosmic microwave background (CMB) anisotropies. The evolution of cosmological perturbations of CHAMP with other components is followed in a self-consistent manner, without assuming that CHAMP and baryons are tightly coupled. We incorporate for the first time the "kinetic re-coupling" of the Coulomb scattering, which is characteristic of heavy CHAMPs. By a direct comparison of the predicted CMB temperature/polarization auto-correlations in CHAMP models and the observed spectra in the Planck mission, we show that CHAMPs leave sizable effects on CMB spectra if they are lighter than $10^{11}\\,{\\rm GeV}$. Our result can be applicable to any CHAMP as long as its lifetime is much longer than the cosmic time at the recombination ($\\sim 4 \\times 10^{5}\\, {\\rm yr}$). An application to millicharged particles is also discussed.

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

    CERN Document Server

    Wu, Hao-Yi

    2016-01-01

    Cosmic far-infrared background (CFIRB) probes unresolved dusty star-forming galaxies across cosmic time and is complementary to ultraviolet/optical probes of galaxy evolution. In this work, we interpret the observed CFIRB anisotropies using an empirical model based on recent galaxy survey results, including stellar mass functions, star-forming main sequence, and dust attenuation. Without introducing new parameters, our model agrees well with the CFIRB anisotropies observed by Planck and the submillimeter number counts observed by Herschel. We find that the commonly used linear relation between infrared luminosity and star-formation rate over-produces the observed CFIRB amplitudes, and lower infrared luminosities from low-mass galaxies are required. Our results indicate that CFIRB not only provides a consistency check for galaxy evolution models but also informs the star-formation rate and dust content for low-mass galaxies.

  6. Galactic cosmic ray-induced radiation dose on terrestrial exoplanets.

    Science.gov (United States)

    Atri, Dimitra; Hariharan, B; Grießmeier, Jean-Mathias

    2013-10-01

    This past decade has seen tremendous advancements in the study of extrasolar planets. Observations are now made with increasing sophistication from both ground- and space-based instruments, and exoplanets are characterized with increasing precision. There is a class of particularly interesting exoplanets that reside in the habitable zone, which is defined as the area around a star where the planet is capable of supporting liquid water on its surface. Planetary systems around M dwarfs are considered to be prime candidates to search for life beyond the Solar System. Such planets are likely to be tidally locked and have close-in habitable zones. Theoretical calculations also suggest that close-in exoplanets are more likely to have weaker planetary magnetic fields, especially in the case of super-Earths. Such exoplanets are subjected to a high flux of galactic cosmic rays (GCRs) due to their weak magnetic moments. GCRs are energetic particles of astrophysical origin that strike the planetary atmosphere and produce secondary particles, including muons, which are highly penetrating. Some of these particles reach the planetary surface and contribute to the radiation dose. Along with the magnetic field, another factor governing the radiation dose is the depth of the planetary atmosphere. The higher the depth of the planetary atmosphere, the lower the flux of secondary particles will be on the surface. If the secondary particles are energetic enough, and their flux is sufficiently high, the radiation from muons can also impact the subsurface regions, such as in the case of Mars. If the radiation dose is too high, the chances of sustaining a long-term biosphere on the planet are very low. We have examined the dependence of the GCR-induced radiation dose on the strength of the planetary magnetic field and its atmospheric depth, and found that the latter is the decisive factor for the protection of a planetary biosphere.

  7. The Cosmic Infrared Background Experiment (CIBER): The Wide-Field Imagers

    CERN Document Server

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

    2012-01-01

    We have developed and characterized an imaging instrument to measure the spatial properties of the diffuse near-infrared extragalactic background light in a search for fluctuations from z > 6 galaxies during the epoch of reionization. The instrument is part of the Cosmic Infrared Background Experiment (CIBER), designed to observe the extragalactic background light above the Earth's atmosphere during a suborbital sounding rocket flight. The imaging instrument incorporates a 2x2 degree field of view, to measure fluctuations over the predicted peak of the spatial power spectrum at 10 arcminutes, and 7"x7" pixels, to remove lower redshift galaxies to a depth sufficient to reduce the low-redshift galaxy clustering foreground below instrumental sensitivity. The imaging instrument employs two cameras with \\Delta \\lambda / \\lambda ~0.5 bandpasses centered at 1.1 and 1.6 microns to spectrally discriminate reionization extragalactic background fluctuations from local foreground fluctuations. CIBER operates at wavelengt...

  8. Probing reionization with the cross power spectrum of 21 cm and near-infrared radiation backgrounds

    CERN Document Server

    Mao, Xiao-Chun

    2014-01-01

    The cross-correlation between the 21 cm emission from the high-redshift intergalactic medium and the near-infrared (NIR) background light from the high-redshift galaxies promises to be a powerful probe of cosmic reionization. In this paper, we investigate the cross power spectrum during the epoch of reionization. We employ an improved halo approach to derive the distribution of the density field and consider two stellar populations in the star formation model: metal-free stars and metal-poor stars. The reionization history is further generated to be consistent with the electron-scattering optical depth from cosmic microwave background measurements. Then the intensity of NIR background is estimated by collecting emission from stars in the first-light galaxies. On large scales, we find the 21 cm and NIR radiation backgrounds are positively correlated during the very early stages of reionization. However, these two radiation backgrounds quickly become anti-correlated as reionization proceeds. The maximum absolut...

  9. Quantum collapse as a source of the seeds of cosmic structure during the radiation era

    Science.gov (United States)

    León, Gabriel; Landau, Susana J.; Piccirilli, María Pía

    2014-10-01

    The emergence of the seeds of cosmic structure, from a perfect isotropic and homogeneous Universe, has not been clearly explained by the standard version of inflationary models as the dynamics involved preserve the homogeneity and isotropy at all times. A proposal that attempts to deal with this problem, by introducing "the self-induced collapse hypothesis," has been introduced by D. Sudarsky and collaborators in previous papers. In all these works, the collapse of the wave function of the inflaton mode is restricted to occur during the inflationary period. In this paper, we analyze the possibility that the collapse happens during the radiation era. A viable model can be constructed under the condition that the inflaton field variable must be affected by the collapse while the momentum variable can or cannot be affected. Another condition to be fulfilled is that the time of collapse must be independent of k . However, when comparing with recent observational data, the predictions of the model cannot be distinguished from the ones provided by the standard inflationary scenario. The main reason for this arises from the requirement that primordial power spectrum obtained for the radiation era matches the amplitude of scalar fluctuations consistent with the latest cosmic microwave background observations. This latter constraint results in a limit on the possible times of collapse and ensures that the contribution of the inflaton field to the energy-momentum tensor is negligible compared to the contribution of the radiation fields.

  10. Health Risk Assessment of Natural Background Radiation in Residents of Khorramabad, Iran

    Directory of Open Access Journals (Sweden)

    Mojtaba Ghorbanipour

    2017-03-01

    Full Text Available Introduction Radioactive materials naturally exist in the world. Indeed, approximately 82% of human-absorbed radiation doses, which are out of human control, arise from natural sources of radiation including cosmic, terrestrial, and exposure through inhalation or ingestion. Thus, the aim of the present study was to estimate health risk, as well as the effective and organ doses from naturally occurring background radiation in residents living in the vicinity of Khorramabad, Iran. Materials and Methods This cross-sectional study was carried out in Khorramabad, Iran. The measurements were performed using Geiger-Muller detector (RDS-110 during daylight from April to June, 2015. The natural gamma radiation measurements were made both indoor and outdoor across five regions of Khorramabad (north, south, west, east, and center. Results The estimated mean absorbed dose rate in outdoor and indoor zones were 0.09±0.024 and 0.117±0.032 mSvy-1, respectively. Additionally, the mean annual effective dose was calculated as 0.69±0.19 mSvy-1, while the estimated health risk probability was 0.0345%. Conclusion The average annual effective dose arising from gamma background radiation was higher than global values. Therefore, more studies are required to examine the relationship between radiation-induced effects and the natural background radiation level in Khorramabad.

  11. Biotropic Effect of Radiation Conditions on Orbital Cosmic Stations

    Science.gov (United States)

    Tsetlin, Vladimir; Ushakov, Igor; Gurieva, Tamar; Moisa, Svetlana; Zotin, Alexei; Lobanov, Alexei

    On the orbit of pilot orbital stations the crews undergo to low doses of chronic irradiation of cosmic radiation. The studying of radiobiological effects in different living systems were carried out in the ship’s side (OC “MIR” and ICS) and model surface experiments (power dose 200 mGy/day, density of neutron flow 30 particles/sm2 sec). It was shown that ionized radiation effects on embryonal development of Japanese quail embryo, inducing morphological disturbances in 12% of embryos. Many years ontogenesis (more 15 years of life in OC “MIR”) of microbial association evoked replacement of dominant types of micromycetes and bacterium and increasing of colony-formed units (CFU) in four orders. In laboratory low doses of γ-radiation induced the increasing of flight strain biomass of Aspergillus niger that corresponds to a radiation hormezis and also the increasing of radio-sensitivity. Moreover, under γ-neutron radiation were marked some deviations in morphology of supporting cell and numerous head falls of Aspergillus niger. The irradiation of Protozoa by low doses led to that spontaneous motion activity of spirostoms (Spirostomum ambiguum Ehbg.) accommodated in water processing by mixed γ-neutron radiation decreased twice that testified the fact that the definite factor of γ-neutron radiation effect is the changing of water medium state. In dry seeds of the highest plants wetting in water of preliminary low doses α-and γ-irradiation field in 100-300 times lower than geomagnetic one) the germination of seeds was higher approximately twice under γ-radiation. Low doses of γ-radiation decreased and α-radiation increased a negative influence of hypo-magnetic field on these processes. It was shown that hypomagnetic field occurred, in general, beneficial effect on the development of Planorbarius corneus: the portion of teratogenic effect is decreased, embryos initially occurred in hypomagnetic conditions were characterized by lowering mortality. Mobility

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

    Science.gov (United States)

    Merkel, Philipp M.; Schäfer, Björn Malte

    2017-08-01

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

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

    Science.gov (United States)

    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.

  14. Interpreting the cosmic far-infrared background anisotropies using a gas regulator model

    CERN Document Server

    Wu, Hao-Yi; Teyssier, Romain

    2016-01-01

    Cosmic far-infrared background (CFIRB) is a powerful probe of the history of star formation rate and the connection between baryons and dark matter. In this work, we explore to which extent the CFIRB anisotropies can be reproduced by a simple physical framework for galaxy evolution, the gas regulator (bathtub) model. The model is based on continuity equations for gas, stars, and metals, taking into account cosmic gas accretion, star formation, and gas ejection. Our model not only provides a good fit to the CFIRB power spectra measured by Planck, but also agrees well with the correlation between CFIRB and gravitational lensing, far-infrared galaxy number counts, and bolometric infrared luminosity functions. The strong clustering of CFIRB indicates a large galaxy bias, which corresponds to haloes of mass 10^12.5 Msun at z=2; thus, CFIRB favors strong infrared emission in massive haloes, which is higher than the expectation from the star formation rate. We provide constraints and fitting functions for the cosmic...

  15. B polarization of cosmic microwave background as a tracer of strings

    CERN Document Server

    Seljak, U; Seljak, Uros; Slosar, Anze

    2006-01-01

    String models can produce successful inflationary scenarios in the context of brane collisions and in many of these models cosmic strings may also be produced. In scenarios such as KKLMMT the string contribution is naturally predicted to be well below the inflationary signal for cosmic microwave background (CMB) temperature anisotropies, in agreement with the existing limits. We find that for $B$ type polarization of CMB the situation is reversed and the dominant signal comes from vector modes generated by cosmic strings, which exceeds the gravity wave signal from both inflation and strings. The signal can be detected for a broad range of parameter space: future polarization experiments may be able to detect the string signal down to the string tension $G\\mu=10^{-9}$, although foregrounds and lensing are likely to worsen these limits. We argue that the optimal scale to search for the string signature is at $\\ell\\sim 1000$, but in models with high optical depth the signal from reionization peak at large scales...

  16. Constraining the cosmic radiation density due to lepton number

    Energy Technology Data Exchange (ETDEWEB)

    Mangano, Gianpiero [Istituto Nazionale di Fisica Nucleare - Sezione di Napoli Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Miele, Gennaro [Istituto Nazionale di Fisica Nucleare - Sezione di Napoli Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Dipartimento di Scienze Fisiche, Università di Napoli Federico II Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Pastor, Sergio [Instituto de Física Corpuscular (CSIC-Universitat de València), Ed. Institutos de Investigación, Apdo. correos 22085, E-46071 Valencia (Spain); Pisanti, Ofelia [Istituto Nazionale di Fisica Nucleare - Sezione di Napoli Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Dipartimento di Scienze Fisiche, Università di Napoli Federico II Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Sarikas, Srdjan [Dipartimento di Scienze Fisiche, Università di Napoli Federico II Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Max-Planck-Institut für Physik (Werner-Heisenberg-Institut) Föhringer Ring 6, 80802 München (Germany)

    2013-04-15

    The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis is typically parameterized in terms of the effective number of neutrinos N{sub eff}, and it is a key parameters in cosmological models slightly more general than the successful minimal ΛCDM scenario. This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. We summarize here the results of a recent analysis to determine the BBN bound on N{sub eff} from primordial neutrino–antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations, and considering quite a wide range for the total lepton number in the neutrino sector, η{sub ν}=η{sub ν{sub e}}+η{sub ν{sub μ}}+η{sub ν{sub τ}} and the initial electron neutrino asymmetry η{sub ν{sub e}{sup in}}. Comparing these results with the forthcoming measurement of N{sub eff} by the Planck satellite will give insight on the nature of the radiation content of the universe.

  17. Aircrew Exposure from Cosmic Radiation on Commercial Airline Routes

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, B.J.; McCall, M.J.; Green, A.R.; Bennett, L.G.I.; Pierre, M.; Schrewe, U.J.; O' Brien, K.; Felsberger, E

    2001-07-01

    As a result of the recent recommendations of the ICRP 60, and in anticipation of possible regulation on occupational exposure of Canadian-based aircrew, an extensive study was carried out by the Royal Military College of Canada over a one-year period to measure the cosmic radiation at commercial jet altitudes. A tissue-equivalent proportional counter was used to measure the ambient total dose equivalent rate on 62 flight routes, resulting in over 20,000 data points at one-minute intervals at various altitudes and geomagnetic latitudes (i.e. which span the full cut-off rigidity of the Earth's magnetic field). These data were then compared to similar experimental work at the Physikalisch Technische Bundesanstalt, using a different suite of equipment, to measure separately the low and high linear energy transfer components of the mixed radiation field, and to predictions with the LUIN transport code. All experimental and theoretical results were in excellent agreement. From these data, a semi-empirical model was developed to allow for the interpolation of the dose rate for any global position, altitude and date (i.e. heliocentric potential). Through integration of the dose rate function over a great circle flight path, a computer code was developed to provide an estimate of the total dose equivalent on any route worldwide at any period in the solar cycle. (author)

  18. Measuring Light from the Epoch of Reionization with CIBER, the Cosmic Infrared Background Experiment

    CERN Document Server

    Zemcov, Michael; Battle, John; Bock, James J; Cooray, Asantha; Hristov, Viktor; Keating, Brian; Kim, Min-Gyu; Lee, Dae-Hee; Levenson, Louis; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Mitchell-Wynne, Ketron; Nam, Uk Won; Renbarger, Tom; Smidt, Joseph; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko

    2011-01-01

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

  19. Phase analysis of the cosmic microwave background from an incomplete sky coverage

    CERN Document Server

    Chiang, Lung-Yih

    2007-01-01

    Phases of the spherical harmonic analysis of full-sky cosmic microwave background (CMB) temperature data contain useful information complementary to the ubiquitous angular power spectrum. In this letter we present a new method of phase analysis on incomplete sky maps. They are the Fourier phases of equal-latitude pixel rings of the map, which are related to the mean angle of the trigonometric moments from the full-sky phases. They have an advantage for probing regions of interest without tapping polluted Galactic plane area, and can localize non-Gaussian features and departure from statistical isotropy in the CMB.

  20. Limits on the cosmic infrared background from clustering in COBE/DIRBE maps

    CERN Document Server

    Kashlinsky, A; Odenwald, S

    1997-01-01

    We discuss a new method of estimating the cosmic infrared background (CIB) from the spatial properties of infrared maps and give the limits on the CIB from applying it to the COBE/DIRBE maps. The strongest limits are obtained at mid- to far-IR where foregrounds are bright, but smooth. If the CIB comes from matter clustered like galaxies, the smoothness of the maps implies CIB levels less than $\\sim$(10-15) nW/m$^2$/sr over this wavelength range.

  1. Characterizing the peak in the cosmic microwave background angular power spectrum

    Science.gov (United States)

    Knox; Page

    2000-08-14

    A peak has been unambiguously detected in the cosmic microwave background angular spectrum. Here we characterize its properties with fits to phenomenological models. We find that the TOCO and BOOM/NA data determine the peak location to be in the range 175-243 and 151-259, respectively (at 95% confidence) and determine the peak amplitude to be between approximately 70 and 90 &mgr;K. The peak shape is consistent with inflation-inspired flat, cold dark matter plus cosmological constant models of structure formation with adiabatic, nearly scale invariant initial conditions. It is inconsistent with open models and presents a great challenge to defect models.

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

    Science.gov (United States)

    Tegmark; Zaldarriaga

    2000-09-11

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

  3. Estimate of the cosmological bispectrum from the MAXIMA-1 cosmic microwave background map.

    Science.gov (United States)

    Santos, M G; Balbi, A; Borrill, J; Ferreira, P G; Hanany, S; Jaffe, A H; Lee, A T; Magueijo, J; Rabii, B; Richards, P L; Smoot, G F; Stompor, R; Winant, C D; Wu, J H P

    2002-06-17

    We use the measurement of the cosmic microwave background taken during the MAXIMA-1 flight to estimate the bispectrum of cosmological perturbations. We propose an estimator for the bispectrum that is appropriate in the flat sky approximation, apply it to the MAXIMA-1 data, and evaluate errors using bootstrap methods. We compare the estimated value with what would be expected if the sky signal were Gaussian and find that it is indeed consistent, with a chi(2) per degree of freedom of approximately unity. This measurement places constraints on models of inflation.

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

    Science.gov (United States)

    Hubmayr, J.; Austermann, J.; Beall, J.; Becker, D.; Cho, H.-M.; Datta, R.; Duff, S. M.; Grace, E.; Halverson, N.; Henderson, S. W.; hide

    2015-01-01

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

  5. 9,400 years of cosmic radiation and solar activity from ice cores and tree rings

    National Research Council Canada - National Science Library

    Friedhelm Steinhilber; Jose A. Abreu; Jürg Beer; Irene Brunner; Marcus Christl; Hubertus Fischer; Ulla Heikkilä; Peter W. Kubik; Mathias Mann; Ken G. McCracken; Heinrich Miller; Hiroko Miyahara; Hans Oerter; Frank Wilhelms

    2012-01-01

    .... Cosmic-ray produced radionuclides, such as ¹⁰Be and ¹⁴C which are stored in polar ice cores and tree rings, offer the unique opportunity to reconstruct the history of cosmic radiation and solar activity over many millennia...

  6. Evaluation of High Level Environmental Background Radiation Areas and its Variation in Ramsar

    Directory of Open Access Journals (Sweden)

    Tayyeb Allahverdi Pourfallah

    2012-03-01

    Full Text Available Introduction The exposure of human beings to ionizing radiation from natural sources is a continuing and inescapable feature of life on earth. For most individuals, this exposure exceeds that from all man-made sources combined. Materials and Methods In this study, the annual effective dose in high level environmental background radiation areas (HLEBRAs of northern city of Ramsar in Iran was determined. For dosimetry, a gamma radiation dosimeter was used. Measurements were performed in more than 90 points in five districts with HLEBR around and near hot springs. Results In some areas, the annual effective dose from outdoor external gamma radiation in HLEBRAs (30 mSv/y exceeded the annual effective dose limit for radiation workers. Our results are evident that the population dose from normal background radiation in HLEBRAs is 200 times higher than corresponding values in Ramsar sea shore. To estimate the cosmic ray contribution, dose measurements were performed on the sea surface one km off the sea shore. Conclusion The observed differences over locations and measured doses between this study and the others revealed the dynamic nature of this phenomenon, and necessitate performing the periodic studies in these areas. Moreover, cytogenetic and immunologic researches for studying the long term effects of these high level environmental radiations on the residents of these HLEBRAs are necessary.

  7. Is natural background or radiation from nuclear power plants leukemogenic

    Energy Technology Data Exchange (ETDEWEB)

    Cronkite, E.P.

    1989-01-01

    The objective in this review is to provide some facts about normal hemopoietic cell proliferation relevant to leukemogenesis, physical, chemical, and biological facts about radiation effects with the hope that each person will be able to decide for themselves whether background radiation or emissions from nuclear power plants and facilities significantly add to the spontaneous leukemia incidence. 23 refs., 1 tab.

  8. Introducing CoDa (Cosmic Dawn): Radiation-Hydrodynamics of Galaxy Formation in the Early Universe

    Science.gov (United States)

    Ocvirk, Pierre; Gillet, Nicolas; Shapiro, Paul; Aubert, Dominique; Iliev, Ilian; Romain, Teyssier; Yepes, Gustavo; Choi, Jun-hwan; Sullivan, David; Knebe, Alexander; Gottloeber, Stefan; D'Aloisio, Anson; Park, Hyunbae; Hoffman, Yehuda

    2015-08-01

    CoDa (Cosmic Dawn) is the largest fully coupled radiation hydrodynamics simulation of the reionization of the local Universe to date. It was performed using RAMSES-CUDATON running on 8192 nodes (i.e. 8192 GPUs) on the titan supercomputer at Oak Ridge National Laboratory to simulate a 64 h-1Mpc side box down to z=4.23. In this simulation, reionization proceeds self-consistently, driven by stellar radiation. We compare the simulation's reionization history, ionizing flux density, the cosmic star formation history and the CMB Thompson scattering optical depth with their observational values. Luminosity functions are also in rather good agreement with high redshift observations, although very bright objects (MAB1600 gas filaments present a sheathed structure, with a hot envelope surrounding a cooler core. They are however not able to self-shield, while regions denser than 10^-4.5 H atoms per comoving h^-3cm^3 are. Haloes below M ˜ 3.10^9 M⊙ are severely affected by the expanding, rising UV background: their ISM is quickly photo-heated to temperatures above our star formation threshold and therefore stop forming stars after local reionization has occured. Overall, the haloes between 10^(10-11) M⊙ dominate the star formation budget of the box for most of the Epoch of Reionization. Several additional studies will follow, looking for instance at environmental effects on galaxy properties, and the regimes of accretion.

  9. Modelling the correlation between the thermal Sunyaev Zel'dovich effect and the cosmic infrared background

    CERN Document Server

    Addison, Graeme E; Spergel, David N

    2012-01-01

    We show how the correlation between the thermal Sunyaev Zel'dovich effect (tSZ) from galaxy clusters and dust emission from cosmic infrared background (CIB) sources can be calculated in a halo model framework. Using recent tSZ and CIB models, we find that the size of the tSZ x CIB cross-correlation is approximately 10 per cent at 150 GHz. The contribution to the total angular power spectrum is of order -1 \\mu K^2 at ell=3000, however, this value is uncertain by a factor of two to three, primarily because of CIB source modelling uncertainties. We expect the large uncertainty in this component to degrade upper limits on the kinematic Sunyaev Zel'dovich effect (kSZ), due to similarity in the frequency dependence of the tSZ x CIB and kSZ across the frequency range probed by current Cosmic Microwave Background missions. We also find that the degree of tSZ x CIB correlation is higher for mm x sub-mm spectra than mm x mm, because more of the sub-mm CIB originates at lower redshifts (z<2), where most tSZ clusters ...

  10. A measurement of secondary cosmic microwave background anisotropies with two years of South Pole Telescope observations

    CERN Document Server

    Reichardt, C L; Zahn, O; Aird, K A; Benson, B A; Bleem, L E; Carlstrom, J E; Chang, C L; Cho, H M; Crawford, T M; Crites, A T; de Haan, T; Dobbs, M A; Dudley, J; George, E M; Halverson, N W; Holder, G P; Holzapfel, W L; Hoover, S; Hou, Z; Hrubes, J D; Joy, M; Keisler, R; Knox, L; Lee, A T; Leitch, E M; Lueker, M; Luong-Van, D; McMahon, J J; Mehl, J; Meyer, S S; Millea, M; Mohr, J J; Montroy, T E; Natoli, T; Padin, S; Plagge, T; Pryke, C; Ruhl, J E; Schaffer, K K; Shirokoff, E; Spieler, H G; Staniszewski, Z; Stark, A A; Story, K; van Engelen, A; Vanderlinde, K; Vieira, J D; Williamson, R

    2011-01-01

    We present the first three-frequency South Pole Telescope (SPT) cosmic microwave background (CMB) power spectra. The band powers presented here cover angular scales 2000 < ell < 9400 in frequency bands centered at 95, 150, and 220 GHz. At these frequencies and angular scales, a combination of the primary CMB anisotropy, thermal and kinetic Sunyaev-Zel'dovich (SZ) effects, radio galaxies, and cosmic infrared background (CIB) contributes to the signal. We combine Planck and SPT data at 220 GHz to constrain the amplitude and shape of the CIB power spectrum and find strong evidence for non-linear clustering. We explore the SZ results using a variety of cosmological models for the CMB and CIB anisotropies and find them to be robust with one exception: allowing for spatial correlations between the thermal SZ effect and CIB significantly degrades the SZ constraints. Neglecting this potential correlation, we find the thermal SZ power at 150 GHz and ell = 3000 to be 3.65 +/- 0.69 muK^2, and set an upper limit on...

  11. H-ATLAS: THE COSMIC ABUNDANCE OF DUST FROM THE FAR-INFRARED BACKGROUND POWER SPECTRUM

    Energy Technology Data Exchange (ETDEWEB)

    Thacker, Cameron; Cooray, Asantha; Smidt, Joseph; De Bernardis, Francesco; Mitchell-Wynne, K. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Amblard, A. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Auld, R.; Eales, S.; Pascale, E. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff, CF24 3AA (United Kingdom); Baes, M.; Michalowski, M. J. [Sterrenkundig Observatorium, Universiteit Gent, KrijgslAAn 281 S9, B-9000 Gent (Belgium); Clements, D. L.; Dariush, A.; Hopwood, R. [Physics Department, Imperial College London, South Kensington campus, London, SW7 2AZ (United Kingdom); De Zotti, G. [INAF, Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, I-35122 Padova (Italy); Dunne, L.; Maddox, S. [Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Hoyos, C. [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom); Ibar, E. [UK Astronomy Technology Centre, The Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom); Jarvis, M. [Astrophysics, Department of Physics, Keble Road, Oxford, OX1 3RH (United Kingdom); and others

    2013-05-01

    We present a measurement of the angular power spectrum of the cosmic far-infrared background (CFIRB) anisotropies in one of the extragalactic fields of the Herschel Astrophysical Terahertz Large Area Survey at 250, 350, and 500 {mu}m bands. Consistent with recent measurements of the CFIRB power spectrum in Herschel-SPIRE maps, we confirm the existence of a clear one-halo term of galaxy clustering on arcminute angular scales with large-scale two-halo term of clustering at 30 arcmin to angular scales of a few degrees. The power spectrum at the largest angular scales, especially at 250 {mu}m, is contaminated by the Galactic cirrus. The angular power spectrum is modeled using a conditional luminosity function approach to describe the spatial distribution of unresolved galaxies that make up the bulk of the CFIRB. Integrating over the dusty galaxy population responsible for the background anisotropies, we find that the cosmic abundance of dust, relative to the critical density, to be between {Omega}{sub dust} = 10{sup -6} and 8 Multiplication-Sign 10{sup -6} in the redshift range z {approx} 0-3. This dust abundance is consistent with estimates of the dust content in the universe using quasar reddening and magnification measurements in the Sloan Digital Sky Survey.

  12. Planck Early Results: The Power Spectrum Of Cosmic Infrared Background Anisotropies

    CERN Document Server

    Ade, P A R; Arnaud, M; Ashdown, M; Aumont, J; Baccigalupi, C; Balbi, A; Banday, A J; Barreiro, R B; Bartlett, J G; Battaner, E; Benabed, K; Benoit, A; Bernard, J -P; Bersanelli, M; Bhatia, R; Blagrave, K; Bock, J J; Bonaldi, A; Bonavera, L; Bond, J R; Borrill, J; Bouchet, F R; Bucher, M; Burigana, C; Cabella, P; Cardoso, J -F; Catalano, A; Cayon, L; Challinor, A; Chamballu, A; Chiang, L -Y; Chiang, C; Christensen, P R; Clements, D L; Colombi, S; Couchot, F; Coulais, A; Crill, B P; Cuttaia, F; Danese, L; Davies, R D; Davis, R J; de Bernardis, P; de Gasperis, G; de Rosa, A; de Zotti, G; Delabrouille, J; Delouis, J -M; Desert, F -X; Dole, H; Donzelli, S; Dore, O; Dorl, U; Douspis, M; Dupac, X; Efstathiou, G; Ensslin, T A; Eriksen, H K; Finelli, F; Forni, O; Fosalba, P; Frailis, M; Franceschi, E; Galeotta, S; Ganga, K; Giard, M; Giardino, G; Giraud-Heraud, Y; Gonzalez-Nuevo, J; Gorski, K M; Grain, J; Gratton, S; Gregorio, A; Gruppuso, A; Hansen, F K; Harrison, D; Helou, G; Henrot-Versille, S; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hovest, W; Hoyland, R J; Huffenberger, K M; Jaffe, A H; Jones, W C; Juvela, M; Keihanen, E; Keskitalo, R; Kisner, T S; Kneissl, R; Knox, L; Kurki-Suonio, H; Lagache, G; Lamarre, J -M; Lasenby, A; Laureijs, R J; Lawrence, C R; Leach, S; Leonardi, R; Leroy, C; Lilje, P B; Linden-Vornle, M; Lockman, F J; Lopez-Caniego, M; Lubin, P M; Macias-Perez, J F; MacTavish, C J; Maffei, B; Maino, D; Mandolesi, N; Mann, R; Maris, M; Martin, P; Martinez-Gonzalez, E; Masi, S; Matarrese, S; Matthai, F; Mazzotta, P; Melchiorri, A; Mendes, L; Mennella, A; Mitra, S; Miville-Deschenes, M -A; Moneti, A; Montier, L; Morgante, G; Mortlock, D; Munshi, D; Murphy, A; Naselsky, P; Natoli, P; Netterfield, C B; Norgaard-Nielsen, H U; Novikov, D; Novikov, I; O'Dwyer, I J; Oliver, S; Osborne, S; Pajot, F; Pasian, F; Patanchon, G; Perdereau, O; Perotto, L; Perrotta, F; Piacentini, F; Piat, M; Goncalves, D Pinheiro; Plaszczynski, S; Pointecouteau, E; Polenta, G; Ponthieu, N; Poutanen, T; Prezeau, G; Prunet, S; Puget, J -L; Rachen, J P; Reach, W T; Reinecke, M; Remazeilles, M; Renault, C; Ricciardi, S; Riller, T; Ristorcelli, I; Rocha, G; Rosset, C; Rowan-Robinson, M; Rubino-Martin, J A; Rusholme, B; Sandri, M; Santos, D; Savini, G; Scott, D; Seiffert, M D; Shellard, P; Smoot, G F; Starck, J -L; Stivoli, F; Stolyarov, V; Stompor, R; Sudiwala, R; Sunyaev, R; Sygnet, J -F; Tauber, J A; Terenzi, L; Toffolatti, L; Tomasi, M; Torre, J -P; Tristram, M; Tuovinen, J; Umana, G; Valenziano, L; Vielva, P; Villa, F; Vittorio, N; Wade, L A; Wandelt, B D; White, M; Yvon, D; Zacchei, A; Zonca, A

    2011-01-01

    Using Planck maps of six regions of low Galactic dust emission with a total area of about 140 square degrees, we determine the angular power spectra of Cosmic Infrared Background (CIB) anisotropies from multipole l = 200 to l = 2000 at 217, 353, 545 and 857 GHz. We use observations of HI emission as a tracer of thermal dust emission in order to reduce the already low level of Galactic dust emission and use the 143 GHz Planck maps in these fields to clean out cosmic microwave background anisotropies. Both of these cleaning processes are necessary in order to avoid significant contamination of the CIB signal. We measure correlated CIB structure across frequencies. As expected, the correlation decreases with increasing frequency separation as the contribution of high-redshift galaxies to CIB anisotropies increases with wavelengths. We find no significant difference between the frequency spectrum of the CIB anisotropies and the CIB mean, with dI/I=15% from 217 to 857 GHz. In terms of clustering properties, the Pl...

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

    Science.gov (United States)

    Seljak, Uros

    1994-01-01

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

  14. Cosmic background rejection by means of the calorimeter in the Mu2e experiment at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Pezzullo, Gianantonio, E-mail: pezzullo@pi.infn.it [University of Pisa (Italy); INFN sezione di Pisa (Italy); Murat, Pavel [Fermi National Accelerator Laboratory (United States); Sarra, Ivano; Lucà, Alessandra [INFN Laboratori Nazionali di Frascati (Italy)

    2014-03-01

    Mu2e experiment [J.R. Abrams, et al., Mu2e conceptual design report (http://arxiv.org/abs/1211.7019)] searches for coherent, neutrino-less conversion of muons into electrons in the field of a nucleus with a sensitivity of fews parts in 10{sup −17} (a factor of 10{sup 3}–10{sup 4} over existing limits). Mu2e apparatus takes advantage of high intensity muon beams which hit muon stopping targets (devoted for the capture) and uses a basic detector system which is composed by a low-mass straw tubes tracker and by a LYSO crystal calorimeter. One of the main source of background which afflicts this measure is the cosmic induced background. To suppress and keep that source under control the calorimeter operates both: muon identification (with a muon rejection factor of about 10{sup 2}–10{sup 3}) and fake-signal-electron (created via muon interactions with the experimental set-up) rejection. In this paper a description of the calorimeter role in cosmic suppression is reported showing results from GEANT4 simulations.

  15. Cosmological perturbations of quantum mechanical origin and anisotropy of the microwave background radiation

    CERN Document Server

    Grishchuk, L P

    1994-01-01

    A theory of quantum-mechanical generation of cosmological perturbations is considered. The conclusion of this study is that if the large-angular-scale anisotropy in the cosmic microwave background radiation is caused by the long-wavelength cosmological perturbations of quantum mechanical origin, they are, most likely, gravitational waves, rather than density perturbations or rotational perturbations. Some disagreements with previous publications are clarified. This contribution to the Proceedings is based on Reference~[34]. NOTE: To generate an output, please extract and save the file crckapb.sty which appear at the beginning of the main file.

  16. Comparison of codes assessing radiation exposure of aircraft crew due to galactic cosmic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bottollier-Depois, Jean-Francois [IRSN Institute for Radiological Protection and Nuclear Safety, Fontenay-aux-Roses (France); Beck, Peter; Latocha, Marcin [AIT Austrian Institute of Technology, Vienna (Austria). Health and Environment Dept.; Mares, Vladimir; Ruehm, Werner [HMGU Helmholtz Zentrum Muenchen, Neuherberg (Germany). Inst. of Radiation Protection; Matthiae, Daniel [DLR Deutsches Zentrum fuer Luft- und Raumfahrt, Koeln (Germany). Inst. of Aerospace Medicine; Wissmann, Frank [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    2012-05-15

    The aim of this report is to compare the doses and dose rates calculated by various codes assessing radiation exposure of aircraft crew due to cosmic radiation. Some of the codes are used routinely for radiation protection purposes while others are purely for scientific use. The calculations were done using a set of representative, real flight routes around the globe. The results are presented in an anonymous way. This comparison is of major importance since a real determination of effective dose is not possible and, therefore, the different methods used to evaluate effective doses can be compared. Eleven codes have been used in this comparison exercise organised by EURADOS on harmonization of aircrew dosimetry practices in European countries. Some of these codes are based on simulations of the secondary field of cosmic radiation by Monte Carlo techniques; others use analytical solutions of the problem, while still others are mainly based on a fit to experimental data. The overall agreement between the codes, however, is better than 20 % from the median.

  17. A shallow underground laboratory for low-background radiation measurements and materials development

    Science.gov (United States)

    Aalseth, C. E.; Bonicalzi, R. M.; Cantaloub, M. G.; Day, A. R.; Erikson, L. E.; Fast, J.; Forrester, J. B.; Fuller, E. S.; Glasgow, B. D.; Greenwood, L. R.; Hoppe, E. W.; Hossbach, T. W.; Hyronimus, B. J.; Keillor, M. E.; Mace, E. K.; McIntyre, J. I.; Merriman, J. H.; Myers, A. W.; Overman, C. T.; Overman, N. R.; Panisko, M. E.; Seifert, A.; Warren, G. A.; Runkle, R. C.

    2012-11-01

    Pacific Northwest National Laboratory recently commissioned a new shallow underground laboratory, located at a depth of approximately 30 meters-water-equivalent. This new addition to the small class of radiation measurement laboratories located at modest underground depths houses the latest generation of custom-made, high-efficiency, low-background gamma-ray spectrometers and gas proportional counters. This paper describes the unique capabilities present in the shallow underground laboratory; these include large-scale ultra-pure materials production and a suite of radiation detection systems. Reported data characterize the degree of background reduction achieved through a combination of underground location, graded shielding, and rejection of cosmic-ray events. We conclude by presenting measurement targets and future opportunities.

  18. A shallow underground laboratory for low-background radiation measurements and materials development.

    Science.gov (United States)

    Aalseth, C E; Bonicalzi, R M; Cantaloub, M G; Day, A R; Erikson, L E; Fast, J; Forrester, J B; Fuller, E S; Glasgow, B D; Greenwood, L R; Hoppe, E W; Hossbach, T W; Hyronimus, B J; Keillor, M E; Mace, E K; McIntyre, J I; Merriman, J H; Myers, A W; Overman, C T; Overman, N R; Panisko, M E; Seifert, A; Warren, G A; Runkle, R C

    2012-11-01

    Pacific Northwest National Laboratory recently commissioned a new shallow underground laboratory, located at a depth of approximately 30 meters-water-equivalent. This new addition to the small class of radiation measurement laboratories located at modest underground depths houses the latest generation of custom-made, high-efficiency, low-background gamma-ray spectrometers and gas proportional counters. This paper describes the unique capabilities present in the shallow underground laboratory; these include large-scale ultra-pure materials production and a suite of radiation detection systems. Reported data characterize the degree of background reduction achieved through a combination of underground location, graded shielding, and rejection of cosmic-ray events. We conclude by presenting measurement targets and future opportunities.

  19. A Shallow Underground Laboratory for Low-Background Radiation Measurements and Materials Development

    Energy Technology Data Exchange (ETDEWEB)

    Aalseth, Craig E.; Bonicalzi, Ricco; Cantaloub, Michael G.; Day, Anthony R.; Erikson, Luke E.; Fast, James E.; Forrester, Joel B.; Fuller, Erin S.; Glasgow, Brian D.; Greenwood, Lawrence R.; Hoppe, Eric W.; Hossbach, Todd W.; Hyronimus, Brian J.; Keillor, Martin E.; Mace, Emily K.; McIntyre, Justin I.; Merriman, Jason H.; Myers, Allan W.; Overman, Cory T.; Overman, Nicole R.; Panisko, Mark E.; Seifert, Allen; Warren, Glen A.; Runkle, Robert C.

    2012-11-08

    Abstract: Pacific Northwest National Laboratory recently commissioned a new shallow underground laboratory, located at a depth of approximately 30 meters water-equivalent. This new addition to the small class of radiation measurement laboratories located at modest underground depths worldwide houses the latest generation of custom-made, high-efficiency, low-background gamma-ray spectrometers and gas proportional counters. This manuscript describes the unique capabilities present in the shallow underground laboratory; these include large-scale ultra-pure materials production and a suite of radiation detection systems. Reported data characterize the degree of background reduction achieved through a combination of underground location, graded shielding, and rejection of cosmic-ray events. We conclude by presenting measurement targets and future opportunities.

  20. A shallow underground laboratory for low-background radiation measurements and materials development

    Energy Technology Data Exchange (ETDEWEB)

    Aalseth, C. E.; Bonicalzi, R. M.; Cantaloub, M. G.; Day, A. R.; Erikson, L. E.; Fast, J.; Forrester, J. B.; Fuller, E. S.; Glasgow, B. D.; Greenwood, L. R.; Hoppe, E. W.; Hossbach, T. W.; Hyronimus, B. J.; Keillor, M. E.; Mace, E. K.; McIntyre, J. I.; Merriman, J. H.; Myers, A. W.; Overman, C. T.; Overman, N. R. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States); and others

    2012-11-15

    Pacific Northwest National Laboratory recently commissioned a new shallow underground laboratory, located at a depth of approximately 30 meters-water-equivalent. This new addition to the small class of radiation measurement laboratories located at modest underground depths houses the latest generation of custom-made, high-efficiency, low-background gamma-ray spectrometers and gas proportional counters. This paper describes the unique capabilities present in the shallow underground laboratory; these include large-scale ultra-pure materials production and a suite of radiation detection systems. Reported data characterize the degree of background reduction achieved through a combination of underground location, graded shielding, and rejection of cosmic-ray events. We conclude by presenting measurement targets and future opportunities.

  1. Inside the Meteorite — Bacterial Spore Survival After Exposure to Galactic Cosmic Radiation

    Science.gov (United States)

    Moeller, R.; Berger, T.; Matthiä, D.; Okayasu, R.; Kato, T.; Kitamura, H.; Reitz, G.

    2010-04-01

    Based on their unique resistance to various space parameters, bacterial spores are one of the model systems used for astrobiological studies. In our research, we studied the response of Bacillus subtilis spores to the exposure of galactic cosmic radiation.

  2. Multilayer Polymeric Shielding to Protect Humans from Galactic Cosmic Radiation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In Sub-topic X4.01, NASA has identified a need for advanced radiation-shielding materials and structures to protect humans from the hazards of galactic cosmic...

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

    CERN Document Server

    Kogut, A; 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 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. PIXIE will 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 um 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 l...

  4. Natural background radiation and estimation of gonadal dose rate of population of Chittagong region

    Energy Technology Data Exchange (ETDEWEB)

    Mostofa, M.N.; Ahmed, J.U. (Chittagong Univ. (Bangladesh). Dept. of Physics); Ahmed, R.; Ishaque, A.M. (Nuclear Medicine Center, Chittagong (Bangladesh)); Ahmed, K. (Institute of Nuclear Medicine, Dacca (Bangladesh))

    1981-07-01

    A survey was made on the background radiation to estimate the gonadal dose rate in the district of Chittagong from the year 1978 to 80. This was done with the help of a calibrated Nuclear Chicago transistorized survey meter. The measurements were made in different types of dwellings and occupational buildings constructed with wood, straw/bamboo, tin/bamboo, tin/brick and single and multistoried buildings of brick and concrete. For measurement of outdoor radiation the investigating areas taken were the roads, fields and the Karnafuly river. The variation in the population dose rate as well as gonadal dose rate were observed in different types of dwellings and occupational buildings including outdoors. The average population dose rate including cosmic ray intensity was found to be 172.41+-8.61 mrad/year. Thus, the annual gonadal dose rate due to gamma radiation was found to be 137.92+-6.89 mrad/year.

  5. Evaluation of viscera and other tissues. [cosmic radiation effects

    Science.gov (United States)

    Ellis, J. T.; Kraft, L. M.; Lushbaugh, C. C.; Humason, G. L.; Hartroft, W. S.; Porta, E. A.; Bailey, O. T.; Greep, R. O.; Leach, C. S.; Laird, T.

    1975-01-01

    Histopathological findings in the lungs, livers, bone marrows, small intestines, gonads, kidneys, and other tissues of the four pocket mice (Perognathus longimembris) that survived the Apollo XVII flight were evaluated in the light of their immediate environment and as targets of HZE cosmic ray particles. Results of this study failed to disclose changes that could be ascribed to the HZE particle radiation. Decreased numbers of erythropoietic cells in the bone marrow of the flight mice were probably related to the increased oxygen pressure. The small intestine showed no changes. Ovaries and testes appeared normal. Two of the three surviving male flight mice displayed early stages of spermatogenesis, just as ground-based controls did at the same season. Abnormalities were also not found in the thyroid, parathyroids, adrenals, or kidneys. The status of the juxtaglomerular apparatus could not be evaluated. The lungs exhibited nonspecific slight reactions. A variety of incidental lesions were noted in the livers of both the flight mice and their controls. The heart muscle showed nothing that could be regarded as pathological. Sections of skeletal muscle examined were free from significant change.

  6. Radiative feedback and cosmic molecular gas: the role of different radiative sources

    CERN Document Server

    Maio, U; De Lucia, G; Borgani, S

    2016-01-01

    We present results from multifrequency radiative hydrodynamical chemistry simulations addressing primordial star formation and related stellar feedback from various populations of stars, stellar energy distributions (SEDs) and initial mass functions. Spectra for massive stars, intermediate-mass stars and regular solar-like stars are adopted over a grid of 150 frequency bins and consistently coupled with hydrodynamics, heavy-element pollution and non-equilibrium species calculations. Powerful massive population III stars are found to be able to largely ionize H and, subsequently, He and He$^+$, causing an inversion of the equation of state and a boost of the Jeans masses in the early intergalactic medium. Radiative effects on star formation rates are between a factor of a few and 1 dex, depending on the SED. Radiative processes are responsible for gas heating and photoevaporation, although emission from soft SEDs has minor impacts. These findings have implications for cosmic gas preheating, primordial direct-c...

  7. Ultrahigh Energy Cosmic Rays, The Diffuse High Energy Gamma Ray Background and Anti-protons

    CERN Document Server

    Eichler, David; Gavish, Eyal

    2016-01-01

    Theories for the origin of ultrahigh energy cosmic rays (UHECR) may imply a significant diffuse background in secondary $\\gamma$-rays from the pair cascads the UHECR initiate when interacting with background light. It is shown that, because the spectrum of these secondary $\\gamma$-rays is softer than the measured diffuse $\\gamma$-ray background in the 10-1000 GeV range, the addition of a hard component from the decay of TeV dark matter particles, subject to the implied constraints on its parameters, improves the fit. It is further argued that any compact astrophysical source of $\\bar p$s is unlikely to be as strong as decay of TeV dark matter particles, given bounds set by neutrino observations. The diffuse $\\gamma$-ray background presently sets the strongest lower bound on the lifetime of TeV dark matter particles, and hence on attendant anti-proton production, and further identification of other contributors to this background will further tighten these constraints.

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

    Science.gov (United States)

    De Rossi, María Emilia; Bromm, Volker

    2017-03-01

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

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

    Science.gov (United States)

    Franceschini, Alberto; Rodighiero, Giulia

    2017-07-01

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

  10. Radiative feedback and cosmic molecular gas: the role of different radiative sources

    Science.gov (United States)

    Maio, Umberto; Petkova, Margarita; De Lucia, Gabriella; Borgani, Stefano

    2016-08-01

    We present results from multifrequency radiative hydrodynamical chemistry simulations addressing primordial star formation and related stellar feedback from various populations of stars, stellar spectral energy distributions (SEDs) and initial mass functions. Spectra for massive stars, intermediate-mass stars and regular solar-like stars are adopted over a grid of 150 frequency bins and consistently coupled with hydrodynamics, heavy-element pollution and non-equilibrium species calculations. Powerful massive Population III stars are found to be able to largely ionize H and, subsequently, He and He+, causing an inversion of the equation of state and a boost of the Jeans masses in the early intergalactic medium. Radiative effects on star formation rates are between a factor of a few and 1 dex, depending on the SED. Radiative processes are responsible for gas heating and photoevaporation, although emission from soft SEDs has minor impacts. These findings have implications for cosmic gas preheating, primordial direct-collapse black holes, the build-up of `cosmic fossils' such as low-mass dwarf galaxies, the role of active galactic nuclei during reionization, the early formation of extended discs and angular-momentum catastrophe.

  11. The Distortion of the Cosmic Microwave Background by the Milky Way

    CERN Document Server

    Czaja, Benjamin

    2014-01-01

    The Milky Way can act as a large-scale weak gravitational lens of the cosmic microwave background (CMB). We study this effect using a photon ray-tracing code and a Galactic mass distribution with disk, bulge and halo components. For an observer at the Sun's coordinates in the Galaxy, the bending of CMB photon paths is limited to less than one arcsecond, and only for rays that pass within a few degrees of the Galactic Center. However, the entire sky is affected, resulting in global distortions of the CMB on large angular scales. These distortions can cause the low-order multipoles of a spherical harmonic expansion of the CMB sky temperature to leak into higher-order modes. Thus the component of the CMB dipole that results from the Local Group's motion relative to the local cosmic frame of rest contributes to higher-order moments for an observer in the solar system. With our ray-tracing code we show that the phenomenon is not sensitive to the specific choice of Galactic potential. We also quantitatively rule it...

  12. The Cold Spot in the Cosmic Microwave Background: the Shadow of a Supervoid

    CERN Document Server

    Szapudi, István; Granett, Benjamin R; Frei, Zsolt; Silk, Joseph; Garcia-Bellido, Juan; Burgett, Will; Cole, Shaun; Draper, Peter W; Farrow, Daniel J; Kaiser, Nicholas; Magnier, Eugene A; Metcalfe, Nigel; Morgan, Jeffrey S; Price, Paul; Tonry, John; Wainscoat, Richard

    2014-01-01

    Standard inflationary hot big bang cosmology predicts small fluctuations in the Cosmic Microwave Background (CMB) with isotropic Gaussian statistics. All measurements support the standard theory, except for a few anomalies discovered in the Wilkinson Microwave Anisotropy Probe maps and confirmed recently by the Planck satellite. The Cold Spot is one of the most significant of such anomalies, and the leading explanation of it posits a large void that imprints this extremely cold area via the linear Integrated Sachs-Wolfe (ISW) effect due to the decay of gravitational potentials over cosmic time, or via the Rees-Sciama (RS) effect due to late-time non-linear evolution. Despite several observational campaigns targeting the Cold Spot region, to date no suitably large void was found at higher redshifts $z > 0.3$. Here we report the detection of an $R =(192 \\pm 15) h^{-1}Mpc$ size supervoid of depth $\\delta = -0.13 \\pm 0.03$, and centred at redshift $z = 0.22$. This supervoid, possibly the largest ever found, is la...

  13. Constraints on the interaction and self-interaction of dark energy from cosmic microwave background

    CERN Document Server

    Amendola, L; Tocchini-Valentini, D; Pasqui, A; Amendola, Luca; Quercellini, Claudia; Tocchini-Valentini, Domenico; Pasqui, Alessandro

    2003-01-01

    It is well-known that even high quality cosmic microwave background (CMB) observations are not sufficient on their own to determine the equation of state of the dark energy, due to the effect of the so-called geometric degeneracy at large multipoles and the cosmic variance at small ones. In contrast, we find that CMB data can put tight constraints on another fundamental property of the dark energy, namely its coupling to dark matter. We compare the current high-resolution CMB data to models of dark energy characterized by an inverse power law or exponential potential and by the coupling to dark matter. We determine the curve of degeneracy between the dark energy equation of state and the dimensionless Hubble parameter h and show that even an independent perfect determination of h may be insufficient to distinguish dark energy from a pure cosmological constant with the current dataset. On the other hand, we find that the interaction with dark matter is firmly bounded, regardless of the potential. In terms of t...

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

    CERN Document Server

    Ricotti, Massimo; Mack, Katherine J

    2007-01-01

    We investigate the effect of non-evaporating primordial black holes (PBHs) on the ionization and thermal history of the universe. X-rays emitted by gas accretion onto PBHs modify the cosmic recombination history, producing measurable effects on the spectrum and anisotropies of the Cosmic Microwave Background (CMB). Using the third-year WMAP data and FIRAS data we improve existing upper limits on the abundance of PBHs with masses >0.1 Msun by several orders of magnitude. Fitting WMAP3 data with cosmological models that do not allow for non-standard recombination histories, as produced by PBHs or other early energy sources, may lead to an underestimate of the best-fit values of the amplitude of linear density fluctuations (sigma_8) and the scalar spectral index (n_s). Cosmological parameter estimates are affected because models with PBHs allow for larger values of the Thomson scattering optical depth, whose correlation with other parameters may not be correctly taken into account when PBHs are ignored. Values o...

  15. Design of Dual-Polarization Horn-Coupled Kinetic Inductance Detectors for Cosmic Microwave Background Polarimetry

    CERN Document Server

    Bryan, Sean; Che, George; Day, Peter; Flanigan, Daniel; Johnson, Bradley R; Jones, Glenn; Kjellstrand, Bjorn; Limon, Michele; Mauskopf, Philip; McCarrick, Heather; Miller, Amber; Smiley, Brian

    2015-01-01

    Mapping the polarization of the Cosmic Microwave Background is yielding exciting data on the origin of the universe, the reionization of the universe, and the growth of cosmic structure. Kilopixel arrays represent the current state of the art, but advances in detector technology are needed to enable the larger detector arrays needed for future measurements. Here we present a design for single-band dual-polarization Kinetic Inductance Detectors (KIDs) at 20% bandwidths centered at 145, 220, and 280 GHz. The detection and readout system is nearly identical to the successful photon-noise-limited aluminum Lumped-Element KIDs that have been recently built and tested by some of the authors. Fabricating large focal plane arrays of the feed horns and quarter-wave backshorts requires only conventional precision machining. Since the detectors and readout lines consist only of a single patterned aluminum layer on a SOI wafer, arrays of the detectors can be built commercially or at a standard university cleanroom.

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

    Science.gov (United States)

    Cappelluti, N.; Ranalli, P.; Roncarelli, M.; Arevalo, P.; Zamorani, G.; Comastri, A.; Gilli, R.; Rovilos, E.; Vignali, C.; Allevato, V.; hide

    2013-01-01

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

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

    Science.gov (United States)

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

    2016-06-01

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

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-01

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

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

    Science.gov (United States)

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

    2013-08-01

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

  1. Asymptotic freedom in the early big bang and the isotropy of the cosmic microwave background

    Science.gov (United States)

    Stecker, F. W.

    1980-01-01

    It is suggested that a superunified field theory incorporating gravity and possessing asymptotic freedom could provide a solution to the problem of the isotropy of the universal 3 K background radiation. Thermal equilibrium could be established in this context through interactions occurring in a temporally indefinite pre-Planckian era.

  2. Asymptotic freedom in the early big-bang and the isotropy of the cosmic microwave background

    Science.gov (United States)

    Stecker, F. W.

    1979-01-01

    The isotropy of the universal 3K background radiation is discussed and a superunified field theory incorporating gravity and possessing asymptotic freedom is suggested to provide a solution to the problem. Thermal equilibrium is established in this context through interactions occurring in a temporally indefinite preplanckian era.

  3. Testing the Interacting Dark Energy Model with Cosmic Microwave Background Anisotropy and Observational Hubble Data

    Directory of Open Access Journals (Sweden)

    Weiqiang Yang

    2017-07-01

    Full Text Available The coupling between dark energy and dark matter provides a possible approach to mitigate the coincidence problem of the cosmological standard model. In this paper, we assumed the interacting term was related to the Hubble parameter, energy density of dark energy, and equation of state of dark energy. The interaction rate between dark energy and dark matter was a constant parameter, which was, Q = 3 H ξ ( 1 + w x ρ x . Based on the Markov chain Monte Carlo method, we made a global fitting on the interacting dark energy model from Planck 2015 cosmic microwave background anisotropy and observational Hubble data. We found that the observational data sets slightly favored a small interaction rate between dark energy and dark matter; however, there was not obvious evidence of interaction at the 1 σ level.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R [Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Hanany, Shaul [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Matsumura, Tomotake [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Johnson, Bradley [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Jones, Terry [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

    2005-02-01

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

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

    Science.gov (United States)

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

    2005-02-01

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

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

    Science.gov (United States)

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

    2017-02-01

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

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

    CERN Document Server

    DeAbreu, Adam; Scott, Douglas

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Kogut, A.; Bensadoun, M.; De Amici, G.; Levin, S.; Limon, M.; Smoot, G. (Lawrence Berkeley Lab., CA (USA)); Sironi, G. (Milan Univ. (Italy). Dipt. di Fisica); Bersanelli, M.; Bonelli, G. (Consiglio Nazionale delle Ricerche, Milan (Italy))

    1989-10-01

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

  9. Studying Heavy Ion Collisions Using Methods From Cosmic Microwave Background (CMB Analysis

    Directory of Open Access Journals (Sweden)

    Gaardhøje J. J.

    2014-04-01

    Full Text Available We present and discuss a framework for studying the morphology of high-multiplicity events from relativistic heavy ion collisions using methods commonly employed in the analysis of the photons from the Cosmic Microwave Background (CMB. The analysis is based on the decomposition of the distribution of the number density of (charged particles expressed in polar and azimuthal coordinates into a sum of spherical harmonic functions. We present an application of the method exploting relevant symmetries to the study of azimuthal correlations arizing from collective flow among charged particles produced in relativistic heavy ion collisions. We discuss perspectives for event-by- event analyses, which with increasing collision energy will eventually open entirely new dimensions in the study of ultrarelaticistic heavy ion reactions.

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

    CERN Document Server

    Smith, S; Rocha, G; Smith, Sarah; Challinor, Anthony; Rocha, Graca

    2006-01-01

    The effect of weak gravitational lensing on the cosmic microwave background (CMB) temperature anisotropies and polarization will provide access to cosmological information that cannot be obtained from the primary anisotropies alone. We compare the information content of the lensed B-mode polarization power spectrum, properly accounting for the non-Gaussian correlations between the power on different scales, with that of the unlensed CMB fields and the lensing potential. The latter represent the products of an (idealised) optimal analysis that exploits the lens-induced non-Gaussianity to reconstruct the fields. Compressing the non-Gaussian lensed CMB into power spectra is wasteful and leaves a tight degeneracy between the equation of state of dark energy and neutrino mass that is much stronger than in the more optimal analysis. Despite this, a power spectrum analysis will be a useful first step in analysing future B-mode polarization data. For this reason, we also consider how to extract accurate parameter con...

  11. SPOrt an Experiment Aimed at Measuring the Large Scale Cosmic Microwave Background Polarization

    CERN Document Server

    Carretti, E; Bernardi, G; Cecchini, S; Macculi, C; Sbarra, C; Monari, J; Orfei, A; Poloni, M; Poppi, S; Bölla, G; Bonometto, S A; Gervasi, M; Sironi, G; Zannoni, M; Tucci, M; Baralis, M; Peverini, O A; Tascone, R; Virone, G; Fabbri, R; Nicastro, L; Ng, K W; Razin, V A; Vinyajkin, E N; Sazhin, M V; Strukov, I A

    2002-01-01

    SPOrt (Sky Polarization Observatory) is a space experiment to be flown on the International Space Station during Early Utilization Phase aimed at measuring the microwave polarized emission with FWHM = 7deg, in the frequency range 22-90 GHz. The Galactic polarized emission can be observed at the lower frequencies and the polarization of Cosmic Microwave Background (CMB) at 90 GHz, where contaminants are expected to be less important. The extremely low level of the CMB Polarization signal (< 1 uK) calls for intrinsically stable radiometers. The SPOrt instrument is expressly devoted to CMB polarization measurements and the whole design has been optimized for minimizing instrumental polarization effects. In this contribution we present the receiver architecture based on correlation techniques, the analysis showing its intrinsic stability and the custom hardware development carried out to detect such a low signal.

  12. Is there a quantum gravity effect on the cosmic microwave background power spectrum?

    CERN Document Server

    Bini, Donato

    2015-01-01

    An assessment is made of recent attempts to evaluate how quantum gravity may affect the anisotropy spectrum of the cosmic microwave background. A perturbative scheme for the solution of the Wheeler-DeWitt equation has been found to allow for enhancement of power at large scales, whereas the alternative predicts a suppression of power at large scales. Both effects are corrections which, although conceptually interesting, turn out to be too small to be detected. Another scheme relies upon a Born-Oppenheimer analysis: by using a perturbative approach to the nonlinear ordinary differential equation obeyed by the two-point function for scalar fluctuations, a new family of power spectra have been obtained and studied by the authors.

  13. Re-Ionization and its Imprint on the Cosmic Microwave Background

    CERN Document Server

    Dodelson, S; Dodelson, Scott; Jubas, Jay

    1995-01-01

    Early reionization changes the pattern of anisotropies expected in the cosmic microwave background. To explore these changes, we derive from first principles the equations governing anisotropies, focusing on the interactions of photons with electrons. Vishniac (1987) claimed that second order terms can be large in a re-ionized Universe, so we derive equations correct to second order in the perturbations. There are many more second order terms than were considered by Vishniac. To understand the basic physics involved, we present a simple analytic approximation to the first order equation. Then turning to the sec- ond order equation, we show that the Vishniac term is indeed the only important one. We also present numerical results for a variety of ionization histories [in a standard cold dark matter Universe] and show quantitatively how the sig- nal in several experiments depends on the ionization history. The most pronounced indication of a re-ionized Universe would be seen in very small scale experiments; the...

  14. Large-scale anomalies in the Cosmic Microwave Background as signatures of non-Gaussianity

    CERN Document Server

    Adhikari, Saroj; Erickcek, Adrienne L

    2016-01-01

    We derive a general expression for the probability of observing deviations from statistical isotropy in the cosmic microwave background (CMB) if the primordial fluctuations are non-Gaussian and extend to superhorizon scales. The primary motivation is to properly characterize the monopole and dipole modulations of the primordial power spectrum that are generated by the coupling between superhorizon and subhorizon perturbations. Unlike previous proposals for generating the hemispherical power asymmetry, we do not assume that the power asymmetry results from a single large superhorizon mode. Instead, we extrapolate the observed power spectrum to superhorizon scales and compute the power asymmetry that would result from a specific realization of non-Gaussian perturbations on scales larger than the observable universe. Our study encompasses many of the scenarios that have been put forward as possible explanations for the CMB hemispherical power asymmetry. We confirm our analytic predictions for the probability of ...

  15. Effects of a primordial magnetic field with log-normal distribution on the cosmic microwave background

    CERN Document Server

    Yamazaki, Dai G; Takahashi, Keitaro; 10.1103/PhysRevD.84.123006

    2011-01-01

    We study the effect of primordial magnetic fields (PMFs) on the anisotropies of the cosmic microwave background (CMB). We assume the spectrum of PMFs is described by log-normal distribution which has a characteristic scale, rather than power-law spectrum. This scale is expected to reflect the generation mechanisms and our analysis is complementary to previous studies with power-law spectrum. We calculate power spectra of energy density and Lorentz force of the log-normal PMFs, and then calculate CMB temperature and polarization angular power spectra from scalar, vector, and tensor modes of perturbations generated from such PMFs. By comparing these spectra with WMAP7, QUaD, CBI, Boomerang, and ACBAR data sets, we find that the current CMB data set places the strongest constraint at $k\\simeq 10^{-2.5}$ Mpc$^{-1}$ with the upper limit $B\\lesssim 3$ nG.

  16. Simulation of Cosmic Microwave Background Polarization Fields for AMiBA Experiment

    CERN Document Server

    Park, C G; Park, Chan-Gyung; Park, Changbom

    2002-01-01

    We have made a topological study of cosmic microwave background (CMB) polarization maps by simulating the AMiBA experiment results. A $\\Lambda$CDM CMB sky is adopted to make mock interferometric observations designed for the AMiBA experiment. CMB polarization fields are reconstructed from the AMiBA mock visibility data using the maximum entropy method. We have also considered effects of Galactic foregrounds on the CMB polarization fields. The genus statistic is calculated from the simulated $Q$ and $U$ polarization maps, where $Q$ and $U$ are Stokes parameters. Our study shows that the Galactic foreground emission, even at low Galactic latitude, is expected to have small effects on the CMB polarization field. Increasing survey area and integration time is essential to detect non-Gaussian signals of cosmological origin through genus measurement.

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

    Science.gov (United States)

    DeAbreu, Adam; Contreras, Dagoberto; Scott, Douglas

    2015-12-01

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

  18. Characterizing the Peak in the Cosmic Microwave Background Angular Power Spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Knox, Lloyd [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637 (United States); Page, Lyman [Department of Physics, Princeton University, Princeton, New Jersey (United States)

    2000-08-14

    A peak has been unambiguously detected in the cosmic microwave background angular spectrum. Here we characterize its properties with fits to phenomenological models. We find that the TOCO and BOOM/NA data determine the peak location to be in the range 175-243 and 151-259, respectively (at 95% confidence) and determine the peak amplitude to be between {approx_equal}70 and 90 {mu}K . The peak shape is consistent with inflation-inspired flat, cold dark matter plus cosmological constant models of structure formation with adiabatic, nearly scale invariant initial conditions. It is inconsistent with open models and presents a great challenge to defect models. (c) 2000 The American Physical Society.

  19. Cosmic Infrared Background Fluctuations in Deep Spitzer IRAC Images: Data Processing and Analysis

    CERN Document Server

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

    2009-01-01

    This paper provides a detailed description of the data reduction and analysis procedures that have been employed in our previous studies of spatial fluctuation of the cosmic infrared background (CIB) using deep Spitzer IRAC observations. The self-calibration we apply removes a strong instrumental signal from the fluctuations which would otherwise corrupt our results. The procedures and results for masking bright sources, and modeling faint sources down to levels set by the instrumental noise are presented. Various tests are performed to demonstrate that the resulting power spectra of these fields are not dominated by instrumental or procedural effects. These tests indicate that the large scale (>~30') fluctuations that remain in the deepest fields are not directly related to the galaxies that are bright enough to be individually detected. We provide the parameterization of these power spectra in terms of separate instrument noise, shot noise, and power law components. Our measurements of spatial fluctuations ...

  20. Distinguishing different scenarios of early energy release with spectral distortions of the cosmic microwave background

    CERN Document Server

    Chluba, Jens

    2013-01-01

    Deviations of the cosmic microwave background (CMB) frequency spectrum from a pure blackbody tell an exciting story about the thermal history of our Universe. In this paper we show how well future CMB measurements could decipher this tale, envisioning a PIXIE-like spectrometer, which could improve the distortion constraints obtained with COBE/FIRAS some 20 years ago by at least three orders of magnitude. This opens a large discovery space, offering deep insights to particle and early-universe physics, opportunities that no longer should be left unexplored. Specifically, we consider scenarios with annihilating and decaying relic particles, as well as signatures from the dissipation of primordial small-scale power. PIXIE can potentially rule out different early-universe scenarios, and moreover will allow unambiguous detections in many of the considered cases, as we demonstrate here. We also discuss slightly more futuristic experiments, with several times improved sensitivities, to highlight the large potential ...

  1. Optimization of Transition Edge Sensor Arrays for Cosmic Microwave Background Observations With the South Pole Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Junjia; Ade, P. A. R.; Anderson, A. J.; Avva, J.; Ahmed, Z.; Arnold, K.; Austermann, J. E.; Bender, A. N.; Benson, B. A.; Bleem, L. E.; Byrum, K.; Carlstrom, J. E.; Carter, F. W.; Chang, C. L.; Cho, H. M.; Cliche, J. F.; Cukierman, A.; Czaplewski, D.; Divan, R.; de Haan, T.; Dobbs, M. A.; Dutcher, D.; Everett, W.; Gilbert, A.; Gannon, R.; Guyser, R.; Halverson, N. W.; Harrington, N. L.; Hattori, K.; Henning, J. W.; Hilton, G. C.; Holzapfel, W. L.; Hubmayr, J.; Huang, N.; Irwin, K. D.; Jeong, O.; Khaire, T.; Kubik, D.; Kuo, C. L.; Lee, A. T.; Leitch, E. M.; Meyer, S. S.; Miller, C. S.; Montgomery, J.; Nadolski, A.; Natoli, T.; Nguyen, H.; Novosad, V.; Padin, S.; Pan, Z.; Pearson, J.; Posada, C. M.; Rahlin, A.; Reichardt, C. L.; Ruhl, J. E.; Saliwanchik, B. R.; Sayre, J. T.; Shariff, J. A.; Shirley, I.; Shirokoff, E.; Smecher, G.; Sobrin, J.; Stan, L.; Stark, A. A.; Story, K.; Suzuki, A.; Tang, Q. Y.; Thakur, R. B.; Thompson, K. L.; Tucker, C.; Vanderlinde, K.; Vieira, J. D.; Wang, G.; Whitehorn, N.; Wu, W. L. K.; Yefremenko, V.; Yoon, K. W.

    2017-06-01

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

  2. Systematic effects in polarizing Fourier transform spectrometers for cosmic microwave background observations

    CERN Document Server

    Nagler, Peter C; Kogut, Alan; Tucker, Gregory S

    2015-01-01

    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 these requirements. In this work, we present an analysis of instrumental systematic effects in polarizing Fourier transform spectrometers, 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.

  3. Analyzing weak lensing of the cosmic microwave background using the likelihood function

    CERN Document Server

    Hirata, C M; Hirata, Christopher M.; Seljak, Uros

    2003-01-01

    Future experiments will produce high-resolution temperature maps of the cosmic microwave background (CMB) and are expected to reveal the signature of gravitational lensing by intervening large-scale structures. We construct all-sky maximum-likelihood estimators that use the lensing effect to estimate the projected density (convergence) of these structures, its power spectrum, and cross-correlation with other observables. This contrasts with earlier quadratic-estimator approaches that Taylor-expanded the observed CMB temperature to linear order in the lensing deflection angle; these approaches gave estimators for the temperature-convergence correlation in terms of the CMB three-point correlation function and for the convergence power spectrum in terms of the CMB four-point correlation function, which can be biased and non-optimal due to terms beyond the linear order. We show that for sufficiently weak lensing, the maximum-likelihood estimator reduces to the computationally less demanding quadratic estimator. T...

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

    Energy Technology Data Exchange (ETDEWEB)

    Nagler, Peter C.; Tucker, Gregory S. [Department of Physics, Brown University, Providence, RI 02912 (United States); Fixsen, Dale J.; Kogut, Alan, E-mail: peter.c.nagler@nasa.gov [NASA/Goddard Space Flight Center, Code 553, Greenbelt, MD 20771 (United States)

    2015-11-15

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

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

    Science.gov (United States)

    Hubmayr, J.; Appel, J. W.; Austermann, J. E.; Beall, J. A.; Becker, D.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; hide

    2011-01-01

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

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

    Science.gov (United States)

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

    2009-12-01

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

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

    Science.gov (United States)

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

    2016-08-01

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

  8. Planck 2015 results: XXIII. The thermal Sunyaev-Zeldovich effect-cosmic infrared background correlation

    DEFF Research Database (Denmark)

    Ade, P. A R; Aghanim, N.; Arnaud, M.

    2016-01-01

    We use Planck data to detect the cross-correlation between the thermal Sunyaev-Zeldovich (tSZ) effect and the infrared emission from the galaxies that make up the the cosmic infrared background (CIB). We first perform a stacking analysis towards Planck-confirmed galaxy clusters. We detect infrared...... data; (ii) using an all-sky tSZ map built from Planck frequency maps; and (iii) using cross-spectra between Planck frequency maps. With the three different methods, we detect the tSZ-CIB cross-power spectrum at significance levels of (i) 6σ; (ii) 3σ; and (iii) 4σ. We model the tSZ-CIB cross...

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    Using the Planck 2015 data release (PR2) temperature maps, we separate Galactic thermal dust emission from cosmic infrared background (CIB) anisotropies. For this purpose, we implement a specifically tailored component-separation method, the so-called generalized needlet internal linear combination...... (GNILC) method, which uses spatial information (the angular powerspectra) to disentangle the Galactic dust emission and CIB anisotropies. We produce significantly improved all-sky maps of Planck thermal dust emission, with reduced CIB contamination, at 353, 545, and 857 GHz. By reducing the CIB...... contamination of the thermal dust maps, we provide more accurate estimates of the local dust temperature and dust spectral index over the sky with reduced dispersion, especially at high Galactic latitudes above b = ±20°. We find that the dust temperature is T = (19.4 ± 1.3) K and the dust spectral index is β...

  10. An analysis of constraints on relativistic species from primordial nucleosynthesis and the cosmic microwave background

    CERN Document Server

    Nollett, Kenneth M

    2011-01-01

    We present constraints on the number of relativistic species from a joint analysis of cosmic microwave background (CMB) fluctuations and light element abundances (helium and deuterium) compared to big bang nucleosynthesis (BBN) predictions. Our BBN calculations include updates of nuclear rates in light of recent experimental and theoretical information, with the most significant change occuring for the d(p,gamma)^3He cross section. We calculate a likelihood function for BBN theory and observations that accounts for both observational errors and nuclear rate uncertainties and can be easily embedded in cosmological parameter fitting. We then demonstrate that CMB and BBN are in good agreement, suggesting that the number of relativistic species did not change between the time of BBN and the time of recombination. The level of agreement between BBN and CMB, as well as the agreement with the standard model of particle physics, depends somewhat on systematic differences among determinations of the primordial helium ...

  11. The Age of the Universe and the Cosmological Constant Determined from Cosmic Microwave Background Anisotropy Measurements

    CERN Document Server

    Knox, L; Skordis, C

    2001-01-01

    If Omega_tot = 1 and structure formed from adiabatic initial conditions then the age of the Universe, as constrained by measurements of the cosmic microwave background (CMB), is t=14.0 +/- 0.5 Gyr. The uncertainty is surprisingly small given that CMB data alone constrain neither h nor Omega_Lambda significantly. It is due to the tight (and accidental) correlation of the age with the angle subtended by the sound horizon on the CMB last--scattering surface and thus with the well-determined acoustic peak locations. If we assume either the HST Key Project result h = 0.72 +/- .08 or simply that h > 0.55, we find Omega_Lambda > 0.4 at 95% confidence---another argument for dark energy, independent of supernovae observations. Our analysis is greatly simplified by the Monte Carlo Markov chain approach to Bayesian inference combined with a fast method for calculating angular power spectra.

  12. LIGO Gravitational Wave Detection, Primordial Black Holes, and the Near-IR Cosmic Infrared Background Anisotropies

    Science.gov (United States)

    Kashlinsky, A.

    2016-06-01

    LIGO's discovery of a gravitational wave from two merging black holes (BHs) of similar masses rekindled suggestions that primordial BHs (PBHs) make up the dark matter (DM). If so, PBHs would add a Poissonian isocurvature density fluctuation component to the inflation-produced adiabatic density fluctuations. For LIGO's BH parameters, this extra component would dominate the small-scale power responsible for collapse of early DM halos at z ≳ 10, where first luminous sources formed. We quantify the resultant increase in high-z abundances of collapsed halos that are suitable for producing the first generation of stars and luminous sources. The significantly increased abundance of the early halos would naturally explain the observed source-subtracted near-IR cosmic infrared background (CIB) fluctuations, which cannot be accounted for by known galaxy populations. For LIGO's BH parameters, this increase is such that the observed CIB fluctuation levels at 2-5 μm can be produced if only a tiny fraction of baryons in the collapsed DM halos forms luminous sources. Gas accretion onto these PBHs in collapsed halos, where first stars should also form, would straightforwardly account for the observed high coherence between the CIB and unresolved cosmic X-ray background in soft X-rays. We discuss modifications possibly required in the processes of first star formation if LIGO-type BHs indeed make up the bulk or all of DM. The arguments are valid only if the PBHs make up all, or at least most, of DM, but at the same time the mechanism appears inevitable if DM is made of PBHs.

  13. EPR dosimetry of radiation background in the Urals region

    Energy Technology Data Exchange (ETDEWEB)

    Shishkina, E.A.; Degteva, M.O.; Shved, V.A. [Urals Research Center for Radiation Medicine, 48-A Vorovsky, Chelyabinsk 454076 (Russian Federation); Fattibene, P.; Onori, S. [Istituto Superiore di Sanita and Istituto Nazionale di Fisica Nucleare (Italy); Wieser, A. [GSF, Forschungszentrum fuer Umwelt und Gesundheit, Ingolstaedter Landstr (Germany); Ivanov, D.V.; Bayankin, S.N. [Institute of Metal Physics, Russian Academy of Sciences (Russian Federation); Knyazev, V.A.; Vasilenko, E.I.; Gorelov, M. [ZAO, Closed Corporation ' Company GEOSPETSECOLOGIA' (Russian Federation)

    2006-07-01

    Method of Electron Paramagnetic Resonance is extensively applied to individual retrospective dosimetry. The background dose is unavoidable component of cumulative absorbed dose in the tooth enamel accumulated during the lifetime of donor. Estimation of incidental radiation dose using tooth enamel needs in extraction of background dose. Moreover, the variation of background doses in the population is a limited factor for reliable detection of additional irradiation especially for low dose level. Therefore the accurate knowledge of the natural background radiation dose is a critical element of EPR studies of exposed populations. In the Urals region the method applies for such two large cohorts as the workers of Mayak (Ozersk citizens) and Techa River riverside inhabitants (rural population). Current study aimed to investigate the Urals radiation background detected by EPR spectrometry. For this aim two group of unexposed Urals residents were separated, viz: citizens of Ozersk and rural inhabitants of Chelyabinsk region. Comparison of two investigated territories has demonstrated that from the point of view of radiation background it is impossible to assume the Urals population as uniform. The reliable difference between the urban and rural residents has been found. The average background doses of Ozersk donors is in average 50 mGy higher than those detected for rural residents. The individual variability of background doses for Osersk has been higher than in the rural results. The difference in background dose levels between two population results in different limits of accidental dose detection and individualization. The doses for 'Mayak' workers (Ozyorsk citizens) can be classed as anthropogenic if the EPR measurements exceed 120 mGy for teeth younger than 40 years, and 240 mGy for teeth older than 70 years. The anthropogenic doses for Techa River residents (rural population) would be higher than 95 mGy for teeth younger than 50 years and 270 mGy for

  14. Cosmic constraint on massive neutrinos in viable f(R) gravity with producing ΛCDM background expansion

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Jianbo; Wu, Yabo; Wang, Yan; Yang, Weiqiang [Liaoning Normal University, Department of Physics, Dalian (China); Liu, Molin [Xinyang Normal University, Department of Physics, Xinyang (China)

    2016-12-15

    Tensions between several cosmic observations were found recently, such as the inconsistent values of H{sub 0} (or σ{sub 8}) were indicated by the different cosmic observations. Introducing the massive neutrinos in ΛCDM could potentially solve the tensions. Viable f(R) gravity producing ΛCDM background expansion with massive neutrinos is investigated in this paper. We fit the current observational data: Planck-2015 CMB, RSD, BAO, and SNIa to constrain the mass of neutrinos in viable f(R) theory. The constraint results at 95% confidence level are: Σm{sub ν} < 0.202 eV for the active-neutrino case, m{sub ν,sterile}{sup eff} < 0.757 eV with N{sub eff} < 3.22 for the sterile neutrino case. For the effects due to the mass of the neutrinos, the constraint results on model parameter at 95% confidence level become f{sub R0} x 10{sup -6} > -1.89 and f{sub R0} x 10{sup -6} > -2.02 for two cases, respectively. It is also shown that the fitting values of several parameters much depend on the neutrino properties, such as the cold dark matter density, the cosmological quantities at matter-radiation equality, the neutrino density and the fraction of baryonic mass in helium. Finally, the constraint result shows that the tension between direct and CMB measurements of H{sub 0} gets slightly weaker in the viable f(R) model than that in the base ΛCDM model. (orig.)

  15. The effect of hot gas in early-type galaxies on the cosmic microwave background

    Science.gov (United States)

    Trester, Jeffrey J.; Canizares, Claude R.

    1989-01-01

    The effects on the cosmic microwave background which are due to Compton scattering by the hot gas contained in early-type galaxies (the Sunyaev-Zeldovich effect) are computed. Using the known properties of the gas deduced from X-ray observations, it is found that the fractional attenuation DeltaT/T at the center of a gas-rich galaxy is likely to be less than 10 to the -5th, which is just below current limits of detectability. A distribution function is derived for the attenuation which is due to a population of early-type galaxies out to some redshift and the expected rms fluctuations in the background on subarcmin scales are computed. These fluctuations are comparable to those intrinsic to the microwave background in the 'cold dark matter' scenario on these angular scales, but they fall orders of magnitude below the detection limits and below the level of fluctuations expected from nonlinear density perturbations at the epoch of galaxy formation.

  16. The cosmic infrared background experiment-2 (CIBER-2) for studying the near-infrared extragalactic background light

    Science.gov (United States)

    Shirahata, Mai; Arai, Toshiaki; Battle, John; Bock, James; Cooray, Asantha; Enokuchi, Akito; Hristov, Viktor; Kanai, Yoshikazu; Kim, Min Gyu; Korngut, Phillip; Lanz, Alicia; Lee, Dae-Hee; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Morford, Tracy; Ohnishi, Yosuke; Park, Won-Kee; Sano, Kei; Takeyama, Norihide; Tsumura, Kohji; Wada, Takehiko; Wang, Shiang-Yu; Zemcov, Michael

    2016-07-01

    We present the current status of the Cosmic Infrared Background ExpeRiment-2 (CIBER-2) project, whose goal is to make a rocket-borne measurement of the near-infrared Extragalactic Background Light (EBL), under a collaboration with U.S.A., Japan, South Korea, and Taiwan. The EBL is the integrated light of all extragalactic sources of emission back to the early Universe. At near-infrared wavelengths, measurement of the EBL is a promising way to detect the diffuse light from the first collapsed structures at redshift z˜10, which are impossible to detect as individual sources. However, recently, the intra-halo light (IHL) model is advocated as the main contribution to the EBL, and our new result of the EBL fluctuation from CIBER-1 experiment is also supporting this model. In this model, EBL is contributed by accumulated light from stars in the dark halo regions of low- redshift (zCIBER- 1 experiment, we are now developing a new instrument CIBER-2, which is comprised of a 28.5-cm aluminum telescope and three broad-band, wide-field imaging cameras. The three wide-field (2.3×2.3 degrees) imaging cameras use the 2K×2K HgCdTe HAWAII-2RG arrays, and cover the optical and near-infrared wavelength range of 0.5-0.9 μm, 1.0-1.4 μm and 1.5-2.0 μm, respectively. Combining a large area telescope with the high sensitivity detectors, CIBER-2 will be able to measure the spatial fluctuations in the EBL at much fainter levels than those detected in previous CIBER-1 experiment. Additionally, we will use a linear variable filter installed just above the detectors so that a measurement of the absolute spectrum of the EBL is also possible. In this paper, the scientific motivation and the expected performance for CIBER-2 will be presented. The detailed designs of the telescope and imaging cameras will also be discussed, including the designs of the mechanical, cryogenic, and electrical systems.

  17. CONCORD: comparison of cosmic radiation detectors in the radiation field at aviation altitudes

    Directory of Open Access Journals (Sweden)

    Meier Matthias M.

    2016-01-01

    Full Text Available Space weather can strongly affect the complex radiation field at aviation altitudes. The assessment of the corresponding radiation exposure of aircrew and passengers has been a challenging task as well as a legal obligation in the European Union for many years. The response of several radiation measuring instruments operated by different European research groups during joint measuring flights was investigated in the framework of the CONCORD (COmparisoN of COsmic Radiation Detectors campaign in the radiation field at aviation altitudes. This cooperation offered the opportunity to measure under the same space weather conditions and contributed to an independent quality control among the participating groups. The CONCORD flight campaign was performed with the twin-jet research aircraft Dassault Falcon 20E operated by the flight facility Oberpfaffenhofen of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR. Dose rates were measured at four positions in the atmosphere in European airspace for about one hour at each position in order to obtain acceptable counting statistics. The analysis of the space weather situation during the measuring flights demonstrates that short-term solar activity did not affect the results which show a very good agreement between the readings of the instruments of the different institutes.

  18. CONCORD: comparison of cosmic radiation detectors in the radiation field at aviation altitudes

    Science.gov (United States)

    Meier, Matthias M.; Trompier, François; Ambrozova, Iva; Kubancak, Jan; Matthiä, Daniel; Ploc, Ondrej; Santen, Nicole; Wirtz, Michael

    2016-05-01

    Space weather can strongly affect the complex radiation field at aviation altitudes. The assessment of the corresponding radiation exposure of aircrew and passengers has been a challenging task as well as a legal obligation in the European Union for many years. The response of several radiation measuring instruments operated by different European research groups during joint measuring flights was investigated in the framework of the CONCORD (COmparisoN of COsmic Radiation Detectors) campaign in the radiation field at aviation altitudes. This cooperation offered the opportunity to measure under the same space weather conditions and contributed to an independent quality control among the participating groups. The CONCORD flight campaign was performed with the twin-jet research aircraft Dassault Falcon 20E operated by the flight facility Oberpfaffenhofen of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR). Dose rates were measured at four positions in the atmosphere in European airspace for about one hour at each position in order to obtain acceptable counting statistics. The analysis of the space weather situation during the measuring flights demonstrates that short-term solar activity did not affect the results which show a very good agreement between the readings of the instruments of the different institutes.

  19. Study of the Intensity Time Variations of the Cosmic Radiation.

    Science.gov (United States)

    different neutron multiplicities at Durham and Mt. Washington, and of the Pioneer 8 cosmic-ray telescope indicated the form of the modulation was different for the 11-year variation and for Forbush decreases during 1968-1970.

  20. Cosmological Backgrounds of Gravitational Waves and eLISA/NGO: Phase Transitions, Cosmic Strings and Other Sources

    CERN Document Server

    Binétruy, Pierre; Caprini, Chiara; Dufaux, Jean-François

    2012-01-01

    We review the main cosmological backgrounds of gravitational waves accessible to detectors in space sensitive to the range $10^{-4}$ to $10^{-1}$ Hz, with a special emphasis on those backgrounds due to phase transitions or networks of cosmic strings. We apply this to identify the scientific potential of the NGO/eLISA mission of ESA, regarding the detectability of such cosmological backgrounds.

  1. Analytic solutions in the dyon black hole with a cosmic string: Scalar fields, Hawking radiation and energy flux

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, H.S., E-mail: horacio.santana.vieira@hotmail.com [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, CEP 58051-970, João Pessoa, PB (Brazil); Centro de Ciências, Tecnologia e Saúde, Universidade Estadual da Paraíba, CEP 58233-000, Araruna, PB (Brazil); Bezerra, V.B., E-mail: valdir@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, CEP 58051-970, João Pessoa, PB (Brazil); Silva, G.V., E-mail: gislainevs@hotmail.com [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, CEP 58051-970, João Pessoa, PB (Brazil)

    2015-11-15

    Charged massive scalar fields are considered in the gravitational and electromagnetic field produced by a dyonic black hole with a cosmic string along its axis of symmetry. Exact solutions of both angular and radial parts of the covariant Klein–Gordon equation in this background are obtained, and are given in terms of the confluent Heun functions. The role of the presence of the cosmic string in these solutions is showed up. From the radial solution, we obtain the exact wave solutions near the exterior horizon of the black hole, and discuss the Hawking radiation spectrum and the energy flux. -- Highlights: •A cosmic string is introduced along the axis of symmetry of the dyonic black hole. •The covariant Klein–Gordon equation for a charged massive scalar field in this background is analyzed. •Both angular and radial parts are transformed to a confluent Heun equation. •The resulting Hawking radiation spectrum and the energy flux are obtained.

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

    Science.gov (United States)

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

    2003-11-15

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

  3. Using the Crab Nebula as a high precision calibrator for cosmic microwave background polarimeters

    Science.gov (United States)

    Kaufman, Jonathan; Leon, David; Keating, Brian

    2016-03-01

    The polarization of the cosmic microwave background (CMB) provides a plethora of information about the early universe. Most notably, gravitational waves from the Inflationary epoch (the leading explanation of the origin of the universe) create a unique CMB polarization B-mode signal. An unambiguous detection of the Inflationary B-mode signal would be a window into the physics of the universe as it was 10-36s after the Big Bang, at energy scales many orders of magnitude larger than what the LHC can produce. However, there are several instrumental and astrophysical sources that can obfuscate the Inflationary B-mode signal. One of the most difficult parameters to calibrate for CMB telescopes is the absolute orientation of the antenna’s polarization sensitive axis. A miscalibration of the polarization orientation rotates the much brighter E-mode signal, producing a false B-mode signal. The current best uncertainty on polarization orientation in the CMB community is 0.5∘, set from extrapolating IRAM measurements of the Crab Nebula supernova remnant at 90 GHz to 150 GHz, where the CMB signals peak. This accuracy is not sufficient to convincingly detect B-modes predicted by currently allowable models of Inflation. We suggest to precisely measure the Crab Nebula’s polarization, which can be calibrated absolutely to 0.1∘ from measurements of the polarized emission of Mars, and use these data to calibrate current and upcoming CMB experiments. In addition to Inflationary B-modes, more precise calibration will allow us to better constrain the sum of the neutrino masses and set limits on exotic physics such as parity violation through cosmic polarization rotation.

  4. The lensing and temperature imprints of voids on the cosmic microwave background

    Science.gov (United States)

    Cai, Yan-Chuan; Neyrinck, Mark; Mao, Qingqing; Peacock, John A.; Szapudi, Istvan; Berlind, Andreas A.

    2017-04-01

    We have searched for the signature of cosmic voids in the cosmic microwave background (CMB), in both the Planck temperature and lensing-convergence maps; voids should give decrements in both. We use ZOBOV voids from the Data Release 12 Sloan Digital Sky Survey CMASS galaxy sample. We base our analysis on N-body simulations, to avoid a posteriori bias. For the first time, we detect the signature of voids in CMB lensing: the significance is 3.2σ, close to Λ cold dark matter (ΛCDM) in both amplitude and projected density-profile shape. A temperature dip is also seen, at modest significance (2.3σ), with an amplitude about six times the prediction. This temperature signal is induced mostly by voids with radii between 100 and 150 h-1 Mpc, while the lensing signal is mostly contributed by smaller voids - as expected; lensing relates directly to density, while integrated Sachs-Wolfe effect (ISW) depends on gravitational potential. The void abundance in observations and simulations agree as well. We also repeated the analysis excluding lower significance voids: no lensing signal is detected with an upper limit of about twice the ΛCDM prediction. But the mean temperature decrement now becomes non-zero at the 3.7σ level (similar to that found by Granett et al.), with an amplitude about 20 times the prediction. However, the observed dependence of temperature on void size is in poor agreement with simulations, whereas the lensing results are consistent with ΛCDM theory. Thus, the overall tension between theory and observations does not favour non-standard theories of gravity, despite the hints of an enhanced amplitude for the ISW effect from voids.

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

    Science.gov (United States)

    Ricotti, Massimo; Ostriker, Jeremiah P.; Mack, Katherine J.

    2008-06-01

    We investigate the effect of nonevaporating primordial black holes (PBHs) on the ionization and thermal history of the universe. X-rays emitted by gas accretion onto PBHs modify the cosmic recombination history, producing measurable effects on the spectrum and anisotropies of the cosmic microwave background (CMB). Using the third-year WMAP data and COBE FIRAS data we improve existing upper limits on the abundance of PBHs with masses >0.1 M⊙ by several orders of magnitude. The new upper limits still allow PBHs to be important for the origin of supermassive black holes and ultraluminous X-ray sources. Fitting WMAP3 data with cosmological models that do not allow for nonstandard recombination histories, as produced by PBHs or other early energy sources, may lead to an underestimate of the best-fit values of the amplitude of linear density fluctuations (σ8) and the scalar spectral index (ns). Cosmological parameter estimates are affected because models with PBHs allow for larger values of the Thomson scattering optical depth, whose correlation with other parameters may not be correctly taken into account when PBHs are ignored. Values of τe ~ 0.2, ns ~ 1, and σ8 ~ 0.9 are allowed at 95% CF. This result may relieve recent tension between WMAP3 data and clusters data on the value of σ8. PBHs may increase the primordial molecular hydrogen abundance by up to 2 orders of magnitude, this promoting cooling and star formation. The suppression of galaxy formation due to X-ray heating is negligible for models consistent with the CMB data. Thus, the formation rate of the first galaxies and stars would be enhanced by a population of PBHs.

  6. Scalar Radiation in the Background of a Naked Singularity

    CERN Document Server

    Dey, Anshuman; Sarkar, Tapobrata

    2013-01-01

    We study scalar radiation spectra from a particle in circular orbit, in the background of the Janis-Newman-Winicour (JNW) naked singularity. The differences in the nature of the spectra, from what one obtains with a Schwarzschild black hole, is established. We also compute the angular distribution of the spectra.

  7. Study of radiation background at the north crossing point

    Institute of Scientific and Technical Information of China (English)

    MO Xiao-Hu; QIN Qing; QU Hua-Min; WANG Yi-Fang; XU Jin-Qiang; ZHANG Tian-Bao; ZHANG Jian-Yong; ZHANG Qing-Jiang; Achasov Mikhail; CAI Xiao; FU Cheng-Dong; Harris Fred; LIU Qian; Muchnoi Nikolay

    2011-01-01

    Understanding the radiation background at the north crossing point (NCP) in the tunnel of BEPCII is crucial for the performance safety of the High Purity Germanium (HPGe) detector, and in turn of great significance for long-term stable running of the energy measurement system. Therefore, as the first step, a NaI(Tl) detector is constructed to continuously measure the radiation level of photons as background for future experiments. Furthermore, gamma and neutron dosimeters are utilized to explore the radiation distribution in the vicinity of the NCP where the HPGe detector will be located. Synthesizing all obtained information, the shielding for neutron irradiation is studied based on model-dependent theoretical analysis.

  8. Background radiation effects and hazards in planetary instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, Gillian [Space Research Centre, Michael Atiyah Building, Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, (United Kingdom)]. E-mail: gib@star.le.ac.uk; Sims, Mark R. [Space Research Centre, Michael Atiyah Building, Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, (United Kingdom); Fraser, George [Space Research Centre, Michael Atiyah Building, Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, (United Kingdom); Klingelhoefer, Goestar [Institut fuer Anorganische und Analytische Chemie, Johannes-Gutenberg-Universitaet, Staudinger Weg 9, 55128 Mainz (Germany); Bernhardt, Bodo [Institut fuer Anorganische und Analytische Chemie, Johannes-Gutenberg-Universitaet, Staudinger Weg 9, 55128 Mainz (Germany); Davidson, Andrew [EADS Astrium, Gunnels Wood Road, Stevenage SG1 2AS, (United Kingdom)

    2006-08-01

    Recent and proposed future planetary missions are becoming increasingly concerned with detailed geochemical assessment, often in a bid to ascertain the presence of water and life supporting geochemical systems. The instruments involved may use some kind of radioactive source, e.g. X-ray fluorescence spectrometry, Moessbauer spectrometry, neutron scattering. Having radioactive sources on a lander/rover poses various potential problems, in regard to both safety to personnel involved in the building of the instrument and to radiation effects on spacecraft structure and on other instruments. Indeed background radiation effects from one instrument may dominate measurements in another resulting in loss of scientific performance. Drawing on experience with the Beagle 2 probe which contained two instruments with radioactive sources, we present a discussion on the management of radiation hazards and background effects posed by radioactive sources for such planetary missions.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bock, J.; Battle, J. [Jet Propulsion Laboratory (JPL), National Aeronautics and Space Administration (NASA), Pasadena, CA 91109 (United States); Sullivan, I. [Department of Physics, University of Washington, Seattle, WA 98195 (United States); Arai, T.; Matsumoto, T.; Matsuura, S.; Tsumura, K. [Department of Space Astronomy and Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa 252-5210 (Japan); Cooray, A.; Mitchell-Wynne, K.; Smidt, J. [Center for Cosmology, University of California, Irvine, CA 92697 (United States); Hristov, V.; Lam, A. C.; Levenson, L. R.; Mason, P. [Department of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Keating, B.; Renbarger, T. [Department of Physics, University of California, San Diego, San Diego, CA 92093 (United States); Kim, M. G. [Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, D. H. [Institute of Astronomy and Astrophysics, Academia Sinica, National Taiwan University, Taipei 10617, Taiwan (China); Nam, U. W. [Korea Astronomy and Space Science Institute (KASI), Daejeon 305-348 (Korea, Republic of); Suzuki, K. [Instrument Development Group of Technical Center, Nagoya University, Nagoya, Aichi 464-8602 (Japan); and others

    2013-08-15

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

  10. The 21 Centimeter Background from the Cosmic Dark Ages: Minihalos and the Intergalactic Medium before Reionization

    CERN Document Server

    Shapiro, P R; Alvarez, M A; Iliev, I T; Martel, H; Ryu, D; Shapiro, Paul R.; Ahn, Kyungjin; Alvarez, Marcelo A.; Iliev, Ilian T.; Martel, Hugo; Ryu, Dongsu

    2005-01-01

    The H atoms inside minihalos (i.e. halos with virial temperatures T_vir 8) to compute the mean brightness temperature of this background from both minihalos and the intergalactic medium (IGM) prior to the onset of Ly-alpha radiative pumping. We find that the 21-cm signal from gas in collapsed, virialized minihalos dominates over that from the diffuse shocked gas in the IGM.

  11. The 21-cm Background from the Cosmic Dark Ages: Minihalos and the Intergalactic Medium before Reionization

    CERN Document Server

    Ahn, K; Alvarez, M A; Iliev, I T; Martel, H; Ryu, D; Ahn, Kyungjin; Shapiro, Paul R.; Alvarez, Marcelo A.; Iliev, Ilian T.; Martel, Hugo

    2006-01-01

    The H atoms inside minihalos (i.e. halos with virial temperatures T_vir 8) to compute the mean brightness temperature of this background from both minihalos and the intergalactic medium (IGM) prior to the onset of Ly-alpha radiative pumping. We find that the 21-cm signal from gas in collapsed, virialized minihalos dominates over that from the diffuse shocked gas in the IGM.

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

    CERN Document Server

    Abazajian, K N; Austermann, J; Benson, B A; Bischoff, C; Bock, J; Bond, J R; Borrill, J; Calabrese, E; Carlstrom, J E; Carvalho, C S; Chang, C L; Chiang, H C; Church, S; Cooray, A; Crawford, T M; Dawson, K S; Das, S; Devlin, M J; Dobbs, M; Dodelson, S; Dore, O; Dunkley, J; Errard, J; Fraisse, A; Gallicchio, J; Halverson, N W; Hanany, S; Hildebrandt, S R; Hincks, A; Hlozek, R; Holder, G; Holzapfel, W L; Honscheid, K; Hu, W; Hubmayr, J; Irwin, K; Jones, W C; Kamionkowski, M; Keating, B; Keisler, R; Knox, L; Komatsu, E; Kovac, J; Kuo, C -L; Lawrence, C; Lee, A T; Leitch, E; Linder, E; Lubin, P; McMahon, J; Miller, A; Newburgh, L; Niemack, M D; Nguyen, H; Nguyen, H T; Page, L; Pryke, C; Reichardt, C L; Ruhl, J E; Sehgal, N; Seljak, U; Sievers, J; Silverstein, E; Slosar, A; Smith, K M; Spergel, D; Staggs, S T; Stark, A; Stompor, R; Vieregg, A G; Wang, G; Watson, S; Wollack, E J; Wu, W L K; Yoon, K W; Zahn, O

    2013-01-01

    This is a report on the status and prospects of the quantification of neutrino properties through the cosmological neutrino background for the Cosmic Frontier of the Division of Particles and Fields Community Summer Study long-term planning exercise. Experiments planned and underway are prepared to study the cosmological neutrino background in detail via its influence on distance-redshift relations and the growth of structure. The program for the next decade described in this document, including upcoming spectroscopic galaxy surveys eBOSS and DESI and a new Stage-IV CMB polarization experiment CMB-S4, will achieve sigma(sum m_nu) = 16 meV and sigma(N_eff) = 0.020. Such a mass measurement will produce a high significance detection of non-zero sum m_nu, whose lower bound derived from atmospheric and solar neutrino oscillation data is about 58 meV. If neutrinos have a minimal normal mass hierarchy, this measurement will definitively rule out the inverted neutrino mass hierarchy, shedding light on one of the most...

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

    Science.gov (United States)

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

    2011-01-01

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

  14. The Cosmic Infrared Background Experiment: Flight Characterization Of The Ciber Narrow Band Spectrometer.

    Science.gov (United States)

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

    2011-01-01

    Subtraction of the Zodiacal light foreground is the dominant source of uncertainty in absolute photometric measurements of the extra-galactic background at near-infrared to optical wavelengths. The second flight of the Cosmic Infrared Background ExpeRiment (CIBER) occurred on July 10th, 2010. CIBER is a NASA sounding rocket experiment carrying four co-aligned instruments including two imaging telescopes with wide passbands centered at 1 and 1.6 microns, respectively, as well as a low resolution spectrometer and a narrow-band spectrometer. THE CIBER spectrometers are absolutely calibrated in collaboration with NIST. The narrow-band spectrometer filter is centered on the Ca II solar Fraunhofer line at 854.2 nm and is designed to measure the equivalent width of the solar line reflected by the interplanetary dust in order to obtain an absolute measurement of the Zodiacal contribution to the infrared sky at that wavelength. In conjunction with measured low resolution spectrum from 700 to 1900 nm, this will provide an accurate independent check of the DIRBE Zodiacal light models. Here we describe the NBS instrument, calibration and in-flight characterization.

  15. Neutrino physics from the cosmic microwave background and large scale structure

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-01

    This is a report on the status and prospects of the quantification of neutrino properties through the cosmological neutrino background for the Cosmic Frontier of the Division of Particles and Fields Community Summer Study long-term planning exercise. Experiments planned and underway are prepared to study the cosmological neutrino background in detail via its influence on distance-redshift relations and the growth of structure. The program for the next decade described in this document, including upcoming spectroscopic galaxy surveys eBOSS and DESI and a new Stage-IV CMB polarization experiment CMB-S4, will achieve σ (σmν) = 16 meV and σ (Neff) = 0.020. Such a mass measurement will produce a high significance detection of non-zero σmν , whose lower bound derived from atmospheric and solar neutrino oscillation data is about 58 meV. If neutrinos have a minimal normal mass hierarchy, this measurement will definitively rule out the inverted neutrino mass hierarchy, shedding light on one of the most puzzling aspects of the Standard Model of particle physics — the origin of mass. This precise a measurement of Neff will allow for high sensitivity to any light and dark degrees of freedom produced in the big bang and a precision test of the standard cosmological model prediction that Neff=3.046 .

  16. Reionization on Large Scales II: Detecting Patchy Reionization through Cross Correlation of the Cosmic Microwave Background

    CERN Document Server

    Natarajan, Aravind; Trac, Hy; Pen, Ue Li; Loeb, Abraham

    2012-01-01

    We investigate the effect of patchy reionization on the cosmic microwave background temperature. An anisotropic optical depth tau (theta) alters the TT power spectrum on small scales l > 2000. We make use of the correlation between the matter density and the reionization redshift fields to construct full sky maps of tau(theta). Patchy reionization transfers CMB power from large scales to small scales, resulting in a non-zero cross correlation between large and small angular scales. We show that the patchy tau correlator is sensitive to small root mean square values tau_rms ~ 0.003 seen in our maps. We include other secondary anisotropies such as CMB lensing, kinetic and thermal Sunyaev-Zel'dovich terms, as well as the infrared and point source background, and show that patchy reionization may be detected in the low frequency channels ~ 90 GHz, particularly for extended reionization histories. If frequency dependent secondaries can be minimized by a multi-frequency analysis, we show that even small degrees of ...

  17. Neutrino physics from the cosmic microwave background and large scale structure

    Energy Technology Data Exchange (ETDEWEB)

    Abazajian, K. N.; Arnold, K.; Austermann, J. E.; Benson, B. A.; Bischoff, C.; Brock, J.; Bond, J. R.; Borrill, J.; Calabrese, E.; Carlstrom, J. E.; Chang, C. L.

    2015-03-15

    This is a report on the status and prospects of the quantification of neutrino properties through the cosmological neutrino background for the Cosmic Frontier of the Division of Particles and Fields Community Summer Study long-term planning exercise. Experiments planned and underway are prepared to study the cosmological neutrino background in detail via its influence on distance-redshift relations and the growth of structure. The program for the next decade described in this document, including upcoming spectroscopic galaxy surveys eBOSS and DESI and a new Stage-IV CMB polarization experiment CMB-S4, will achieve σ (σmν)(σmν) = 16 meV and σ (Neff)(Neff) = 0.020. Such a mass measurement will produce a high significance detection of non-zero σmνσmν, whose lower bound derived from atmospheric and solar neutrino oscillation data is about 58 meV. If neutrinos have a minimal normal mass hierarchy, this measurement will definitively rule out the inverted neutrino mass hierarchy, shedding light on one of the most puzzling aspects of the Standard Model of particle physics — the origin of mass. This precise a measurement of NeffNeff will allow for high sensitivity to any light and dark degrees of freedom produced in the big bang and a precision test of the standard cosmological model prediction that View the MathML sourceNeff=3.046.

  18. Suppressing Background Radiation Using Poisson Principal Component Analysis

    CERN Document Server

    Tandon, P; Dubrawski, A; Labov, S; Nelson, K

    2016-01-01

    Performance of nuclear threat detection systems based on gamma-ray spectrometry often strongly depends on the ability to identify the part of measured signal that can be attributed to background radiation. We have successfully applied a method based on Principal Component Analysis (PCA) to obtain a compact null-space model of background spectra using PCA projection residuals to derive a source detection score. We have shown the method's utility in a threat detection system using mobile spectrometers in urban scenes (Tandon et al 2012). While it is commonly assumed that measured photon counts follow a Poisson process, standard PCA makes a Gaussian assumption about the data distribution, which may be a poor approximation when photon counts are low. This paper studies whether and in what conditions PCA with a Poisson-based loss function (Poisson PCA) can outperform standard Gaussian PCA in modeling background radiation to enable more sensitive and specific nuclear threat detection.

  19. Background Radiation Measurements at High Power Research Reactors

    CERN Document Server

    Ashenfelter, J; Baldenegro, C X; Band, H R; Barclay, G; Bass, C D; Berish, D; Bowden, N S; Bryan, C D; Cherwinka, J J; Chu, R; Classen, T; Davee, D; Dean, D; Deichert, G; Dolinski, M J; Dolph, J; Dwyer, D A; Fan, S; Gaison, J K; Galindo-Uribarri, A; Gilje, K; Glenn, A; Green, M; Han, K; Hans, S; Heeger, K M; Heffron, B; Jaffe, D E; Kettell, S; Langford, T J; Littlejohn, B R; Martinez, D; McKeown, R D; Morrell, S; Mueller, P E; Mumm, H P; Napolitano, J; Norcini, D; Pushin, D; Romero, E; Rosero, R; Saldana, L; Seilhan, B S; Sharma, R; Stemen, N T; Surukuchi, P T; Thompson, S J; Varner, R L; Wang, W; Watson, S M; White, B; White, C; Wilhelmi, J; Williams, C; Wise, T; Yao, H; Yeh, M; Yen, Y -R; Zhang, C; Zhang, X

    2016-01-01

    Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including $\\gamma$-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.

  20. Background radiation measurements at high power research reactors

    Energy Technology Data Exchange (ETDEWEB)

    Ashenfelter, J. [Wright Laboratory, Department of Physics, Yale University, New Haven, CT 06520 (United States); Balantekin, B. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Baldenegro, C.X. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Band, H.R. [Wright Laboratory, Department of Physics, Yale University, New Haven, CT 06520 (United States); Barclay, G. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Bass, C.D. [Department of Chemistry and Physics, Le Moyne College, Syracuse, NY 13214 (United States); Berish, D. [Department of Physics, Temple University, Philadelphia, PA 19122 (United States); Bowden, N.S., E-mail: nbowden@llnl.gov [Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Bryan, C.D. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Cherwinka, J.J. [Physical Sciences Laboratory, University of Wisconsin, Madison, WI 53706 (United States); Chu, R. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Classen, T. [Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Davee, D. [Department of Physics, College of William and Mary, Williamsburg, VA 23187 (United States); Dean, D.; Deichert, G. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Dolinski, M.J. [Department of Physics, Drexel University, Philadelphia, PA 19104 (United States); Dolph, J. [Physics Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Dwyer, D.A. [Physics Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Fan, S. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); and others

    2016-01-11

    Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including γ-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.

  1. The Effects of the Ionizing Radiation Background on Galaxy Evolution

    CERN Document Server

    Hambrick, D Clay; Naab, Thorsten; Johansson, Peter H

    2009-01-01

    We find that the amount and nature of the assumed ionizing background can strongly affect galaxy formation and evolution. Galaxy evolution simulations typically incorporate an ultraviolet background which falls off rapidly above z=3; e.g., that of Haardt & Madau (1996). However, this decline may be too steep to fit the WMAP constraints on electron scattering optical depth or observations of intermediate redshift (z ~ 2-4) Ly-alpha forest transmission. As an alternative, we present simulations of the cosmological formation of individual galaxies with UV backgrounds that decline more slowly at high redshift: both a simple intensity rescaling and the background recently derived by Faucher-Giguere (2009), which softens the spectrum at higher redshifts. We also test an approximation of the X-ray background with a similar z-dependence. We find for the test galaxies that an increase in either the intensity or hardness of ionizing radiation generically pushes star formation towards lower redshifts: although overa...

  2. The Atacama Cosmology Telescope: A Measurement of the 600< ell <8000 Cosmic Microwave Background Power Spectrum at 148 GHz

    CERN Document Server

    Fowler, J W; Ade, P A R; Aguirre, P; Amiri, M; Appel, J W; Barrientos, L F; Battistelli, E S; Bond, J R; Brown, B; Burger, B; Chervenak, J; Das, S; Devlin, M J; Dicker, S R; Doriese, W B; Dunkley, J; Dünner, R; Essinger-Hileman, T; Fisher, R P; Hajian, A; Halpern, M; Hasselfield, M; Hernández-Monteagudo, C; Hilton, G C; Hilton, M; Hincks, A D; Hlozek, R; Huffenberger, K M; Hughes, D H; Hughes, J P; Infante, L; Irwin, K D; Jimenez, R; Juin, J B; Kaul, M; Klein, J; Kosowsky, A; Lau, J M; Limon, M; Lin, Y -T; Lupton, R H; Marriage, T A; Marsden, D; Martocci, K; Mauskopf, P; Menanteau, F; Moodley, K; Moseley, H; Netterfield, C B; Niemack, M D; Nolta, M R; Page, L A; Parker, L; Partridge, B; Quintana, H; Reid, B; Sehgal, N; Sievers, J; Spergel, D N; Staggs, S T; Swetz, D S; Switzer, E R; Thornton, R; Trac, H; Tucker, C; Verde, L; Warne, R; Wilson, G; Wollack, E; Zhao, Y

    2010-01-01

    We present a measurement of the angular power spectrum of the cosmic microwave background (CMB) radiation observed at 148 GHz. The measurement uses maps with 1.4' angular resolution made with data from the Atacama Cosmology Telescope (ACT). The observations cover 228 square degrees of the southern sky, in a 4.2-degree-wide strip centered on declination 53 degrees South. The CMB at arcminute angular scales is particularly sensitive to the Silk damping scale, to the Sunyaev-Zel'dovich (SZ) effect from galaxy clusters, and to emission by radio sources and dusty galaxies. After masking the 108 brightest point sources in our maps, we estimate the power spectrum between 600 < \\ell < 8000 using the adaptive multi-taper method to minimize spectral leakage and maximize use of the full data set. Our absolute calibration is based on observations of Uranus. To verify the calibration and test the fidelity of our map at large angular scales, we cross-correlate the ACT map to the WMAP map and recover the WMAP power sp...

  3. Bulk Comptonization of the Cosmic Microwave Background by Extragalactic Jets as a Probe of their Matter Content

    CERN Document Server

    Georganopoulos, M; Perlman, E; Stecker, F; Georganopoulos, {Markos; Kazanas, Demosthenes; Perlman, Eric; Stecker, Floyd

    2005-01-01

    We propose a method for estimating the composition, i.e. the relative amounts of leptons and protons, of extragalactic jets which exhibit X-ray bright knots in their kpc scale jets. The method relies on measuring, or setting upper limits on, the component of the Cosmic Microwave Background (CMB) radiation that is bulk-Comptonized by cold electrons in the relativistically flowing jet. These measurements, along with modeling of the broadband knot emission that constrain the bulk Lorentz factor of the jets, can yield estimates of the jet power carried by protons and leptons. We provide an explicit calculation of the spectrum of the bulk-Comptonized (BC) CMB component and apply these results to PKS 0637--752 and 3C 273, two superluminal quasars with Chandra-detected large scale jets. What makes these sources particularly suited for such a procedure is the absence of significant non-thermal jet emission in the `bridge', the region between the core and the first bright jet knot, which guarantees that most of the el...

  4. Planck 2013 results. XXX. Cosmic infrared background measurements and implications for star formation

    Science.gov (United States)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bethermin, M.; Bielewicz, P.; Blagrave, K.; Bobin, J.; Bock, J. J.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bridges, M.; Bucher, M.; Burigana, C.; Butler, R. C.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chen, X.; Chiang, H. C.; Chiang, L.-Y.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Ghosh, T.; Giard, M.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Hanson, D.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Kalberla, P.; Keihänen, E.; Kerp, J.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lacasa, F.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Langer, M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Leonardi, R.; León-Tavares, J.; Lesgourgues, J.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M. D.; Serra, P.; Shellard, E. P. S.; Spencer, L. D.; Starck, J.-L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Türler, M.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Welikala, N.; White, M.; White, S. D. M.; Winkel, B.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-11-01

    We present new measurements of cosmic infrared background (CIB) anisotropies using Planck. Combining HFI data with IRAS, the angular auto- and cross-frequency power spectrum is measured from 143 to 3000 GHz, and the auto-bispectrum from 217 to 545 GHz. The total areas used to compute the CIB power spectrum and bispectrum are about 2240 and 4400 deg2, respectively. After careful removal of the contaminants (cosmic microwave background anisotropies, Galactic dust, and Sunyaev-Zeldovich emission), and a complete study of systematics, the CIB power spectrum is measured with unprecedented signal to noise ratio from angular multipoles ℓ ~ 150 to 2500. The bispectrum due to the clustering of dusty, star-forming galaxies is measured from ℓ ~ 130 to 1100, with a total signal to noise ratio of around 6, 19, and 29 at 217, 353, and 545 GHz, respectively. Two approaches are developed for modelling CIB power spectrum anisotropies. The first approach takes advantage of the unique measurements by Planck at large angular scales, and models only the linear part of the power spectrum, with a mean bias of dark matter haloes hosting dusty galaxies at a given redshift weighted by their contribution to the emissivities. The second approach is based on a model that associates star-forming galaxies with dark matter haloes and their subhaloes, using a parametrized relation between the dust-processed infrared luminosity and (sub-)halo mass. The two approaches simultaneously fit all auto- and cross-power spectra very well. We find that the star formation history is well constrained up to redshifts around 2, and agrees with recent estimates of the obscured star-formation density using Spitzer and Herschel. However, at higher redshift, the accuracy of the star formation history measurement is strongly degraded by the uncertainty in the spectral energy distribution of CIB galaxies. We also find that the mean halo mass which is most efficient at hosting star formation is log (Meff/M⊙) = 12

  5. Soft X-ray excess in the Coma cluster from a Cosmic Axion Background

    Energy Technology Data Exchange (ETDEWEB)

    Angus, Stephen; Conlon, Joseph P.; Marsh, M.C. David; Powell, Andrew J.; Witkowski, Lukas T., E-mail: stephen.angus@physics.ox.ac.uk, E-mail: j.conlon1@physics.ox.ac.uk, E-mail: david.marsh1@physics.ox.ac.uk, E-mail: andrew.powell2@physics.ox.ac.uk, E-mail: l.witkowski@thphys.uni-heidelberg.de [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)

    2014-09-01

    We show that the soft X-ray excess in the Coma cluster can be explained by a cosmic background of relativistic axion-like particles (ALPs) converting into photons in the cluster magnetic field. We provide a detailed self-contained review of the cluster soft X-ray excess, the proposed astrophysical explanations and the problems they face, and explain how a 0.1- 1 keV axion background naturally arises at reheating in many string theory models of the early universe. We study the morphology of the soft excess by numerically propagating axions through stochastic, multi-scale magnetic field models that are consistent with observations of Faraday rotation measures from Coma. By comparing to ROSAT observations of the 0.2- 0.4 keV soft excess, we find that the overall excess luminosity is easily reproduced for g{sub aγγ} ∼ 2 × 10{sup -13} Ge {sup -1}. The resulting morphology is highly sensitive to the magnetic field power spectrum. For Gaussian magnetic field models, the observed soft excess morphology prefers magnetic field spectra with most power in coherence lengths on O(3 kpc) scales over those with most power on O(12 kpc) scales. Within this scenario, we bound the mean energy of the axion background to 50 eV∼< ( E{sub a} ) ∼< 250 eV, the axion mass to m{sub a} ∼< 10{sup -12} eV, and derive a lower bound on the axion-photon coupling g{sub aγγ} ∼> √(0.5/Δ N{sub eff}) 1.4 × 10{sup -13} Ge {sup -1}.

  6. Background X-ray Radiation Fields Produced by Young Embedded Star Clusters

    CERN Document Server

    Adams, Fred; Holden, Lisa

    2012-01-01

    Most star formation in our galaxy occurs within embedded clusters, and these background environments can affect the star and planet formation processes occurring within them. In turn, young stellar members can shape the background environment and thereby provide a feedback mechanism. This work explores one aspect of stellar feedback by quantifying the background X-ray radiation fields produced by young stellar objects. Specifically, the distributions of X-ray luminosities and X-ray fluxes produced by cluster environments are constructed as a function of cluster membership size $N$. Composite flux distributions, for given distributions of cluster sizes $N$, are also constructed. The resulting distributions are wide and the X-ray radiation fields are moderately intense, with the expected flux levels exceeding the cosmic and galactic X-ray backgrounds by factors of $\\sim10-1000$ (for energies 0.2 -- 15 keV). For circumstellar disks that are geometrically thin and optically thick, the X-ray flux from the backgrou...

  7. Cosmic rays and radiations from the cosmos; Rayons cosmiques et rayonnement du cosmos

    Energy Technology Data Exchange (ETDEWEB)

    Parizot, E

    2005-12-01

    This document gathers a lot of recent information concerning cosmic radiations, it is divided into 4 parts. Part I: energy, mass and angular spectra of cosmic rays. Part II: general phenomenology of cosmic rays, this part deals with the standard model, the maximal energy of protons inside supernova remnants, nucleosynthesis of light elements, and super-bubbles. Part III: radiations from the cosmos, this part deals with high energy gamma rays, non-thermal radiation of super-bubbles, positron transport, and the Compton trail of gamma-ray bursts. Part IV: the Pierre Auger observatory (OPA), this part deals with the detection of gamma ray bursts at OPA, the measurement of anisotropy, and top-down models. (A.C.)

  8. Measurement of background gamma radiation in the northern Marshall Islands.

    Science.gov (United States)

    Bordner, Autumn S; Crosswell, Danielle A; Katz, Ainsley O; Shah, Jill T; Zhang, Catherine R; Nikolic-Hughes, Ivana; Hughes, Emlyn W; Ruderman, Malvin A

    2016-06-21

    We report measurements of background gamma radiation levels on six islands in the northern Marshall Islands (Enewetak, Medren, and Runit onEnewetak Atoll; Bikini and Nam on Bikini Atoll; and Rongelap on Rongelap Atoll). Measurable excess radiation could be expected from the decay of (137)Cs produced by the US nuclear testing program there from 1946 to 1958. These recordings are of relevance to safety of human habitation and resettlement. We find low levels of gamma radiation for the settled island of Enewetak [mean = 7.6 millirem/year (mrem/y) = 0.076 millisievert/year (mSv/y)], larger levels of gamma radiation for the island of Rongelap (mean = 19.8 mrem/y = 0.198 mSv/y), and relatively high gamma radiation on the island of Bikini (mean = 184 mrem/y = 1.84 mSv/y). Distributions of gamma radiation levels are provided, and hot spots are discussed. We provide interpolated maps for four islands (Enewetak, Medren, Bikini, and Rongelap), and make comparisons to control measurements performed on the island of Majuro in the southern Marshall Islands, measurements made in Central Park in New York City, and the standard agreed upon by the United States and the Republic of the Marshall Islands (RMI) governments (100 mrem/y = 1 mSv/y). External gamma radiation levels on Bikini Island significantly exceed this standard (P = <0.01), and external gamma radiation levels on the other islands are below the standard. To determine conclusively whether these islands are safe for habitation, radiation exposure through additional pathways such as food ingestion must be considered.

  9. The chemical composition of the cosmic radiation around the ankle and the related spectral indices

    CERN Document Server

    Codino, Antonio

    2009-01-01

    Some recent measurements of the chemical composition of the cosmic radiation indicate that at the energy of 3 x 10 **18 eV, around the ankle, light cosmic ions dominate the spectrum as it occurs in the preknee energy region. Taking advantage of a recent theory of cosmic radiation which provides a quantitative explanation of the knee, the second knee and the ankle, the chemical composition of cosmic radiation is explicitly calculated giving individual ion spectra and ion fractions from 10 ** 12 eV to 5 x 10 ** 19 eV. The calculation assumes two components of the cosmic radiation feeding the ion flux at Earth: one originated in the disc volume and another one, called extradisc component, which from the disc boundaries traverses the Galaxy reaching the solar system. Data above 10 ** 17 eV collected during half century of experimentation by Auger, HiRes, Agasa, Akeno, Fly' s Eye, Yakutsk, Haverah Park and Volcano Ranch experiments are reviewed, examined and compared with the theoretical . The comparison between c...

  10. Galactic neutrino background from cosmic ray interaction with the ISM content

    CERN Document Server

    De Donato, C; D'Olivo, J C

    2007-01-01

    We use a diffusive model for the propagation of Galactic cosmic rays to estimate the charged pion production in interactions with protons of the interstellar medium. Cosmic ray nuclei from proton to iron are considered and the corresponding contribution to the neutrino secondary flux produced as a result of spallation is also estimated.

  11. Ageing effects on image sensors due to terrestrial cosmic radiation

    NARCIS (Netherlands)

    Nampoothiri, G.G.; Horemans, M.L.R.; Theuwissen, A.J.P.

    2011-01-01

    We analyze the “ageing” effect on image sensors introduced by neutrons present in natural (terrestrial) cosmic environment. The results obtained at sea level are corroborated for the first time with accelerated neutron beam tests and for various image sensor operation conditions. The results reveal

  12. THE MODULATION OF HEAVY NUCLEI IN THE PRIMARY COSMIC RADIATION,

    Science.gov (United States)

    The ntensities of the primary cosmic ray heavy nuclei, Z equal to or greater than 3, have been studied during several Forbush decreases. Fifteen...observed before, during or after four of the largest Forbush decreases that occurred in the last solar cycle. Examination of this data, together with that

  13. Radiative feedback from an early X-ray background

    CERN Document Server

    Glover, S C O; Glover, Simon C.O.; Brand, Peter W.J.L.

    2003-01-01

    The first generation of stars (commonly known as population III) are expected to form in low-mass protogalaxies in which molecular hydrogen is the dominant coolant. Radiation from these stars will rapidly build up an extragalactic ultraviolet background capable of photodissociating H2, and it is widely believed that this background will suppress further star formation in low-mass systems. However, star formation will also produce an extragalactic X-ray background. This X-ray background, by increasing the fractional ionization of protogalactic gas, promotes H2 formation and reduces the effectiveness of ultraviolet feedback. In this paper, we examine which of these backgrounds has the dominant effect. Using a simple model for the growth of the UV and X-ray backgrounds, together with a detailed one-dimensional model of protogalactic chemical evolution, we examine the effects of the X-ray backgrounds produced by a number of likely source models. We show that in several cases, the resulting X-ray background is str...

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

    CERN Document Server

    De Rossi, Maria Emilia

    2016-01-01

    We study the contribution of the first galaxies to the far-infrared/sub-millimeter (FIR/sub-mm) extragalactic background light (EBL) by implementing an analytical model for dust emission. We explore different dust models, assuming different grain size distributions and chemical compositions. According to our findings, observed re-radiated emission from dust in dwarf-size galaxies at $z \\sim 10$ would peak at a wavelength of $\\sim 500 \\mu {\\rm m}$ with observed fluxes of $\\sim 10^{-3} - 10^{-2}$ nJy, which is below the capabilities of current observatories. In order to be detectable, model sources at these high redshifts should exhibit luminosities of $\\gtrsim 10^{12} L_{\\odot}$, comparable to that of local ultra-luminous systems. The FIR/sub-mm EBL generated by primeval galaxies peaks at $\\sim 500 \\mu {\\rm m}$, with an intensity ranging from $\\sim 10^{-4}$ to $10^{-3} {\\rm nW \\ m^{-2} \\ sr^{-1}}$, depending on dust properties. These values are $\\sim 3 - 4$ orders of magnitude below the absolute measured cosmi...

  15. First Detection of Cosmic Microwave Background Lensing and Lyman-{\\alpha} Forest Bispectrum

    CERN Document Server

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

    2016-01-01

    We present the first detection of a correlation between the Lyman-$\\alpha$ forest and cosmic microwave background (CMB) lensing. For each Lyman-$\\alpha$ forest in SDSS-III/BOSS DR12, we correlate the one-dimensional power spectrum with the CMB lensing convergence on the same line of sight from Planck. This measurement constitutes a position-dependent power spectrum, or a squeezed bispectrum, and quantifies the non-linear response of the Lyman-$\\alpha$ forest power spectrum to a large-scale overdensity. The signal is measured at 5~$\\sigma$ and is consistent with the $\\Lambda$CDM expectation. We measure the linear and non-linear biases of the Lyman-$\\alpha$ forest with respect to the dark matter distribution. This new observable provides a consistency check for the Lyman-$\\alpha$ forest as a large-scale structure probe and tests our understanding of the relation between intergalactic gas and dark matter. In the future, it could be used to test hydrodynamical simulations and calibrate the relation between the Ly...

  16. The intrinsic bispectrum of the Cosmic Microwave Background (Ph.D. thesis)

    CERN Document Server

    Pettinari, Guido Walter

    2014-01-01

    [Abridged version] A huge theoretical and experimental effort is being made by cosmologists and particle physicists to gain insight of the mechanism of generation of the primordial cosmological fluctuations, which remains still largely unknown. The bispectrum of the cosmic microwave background (CMB) has been recognised as a powerful probe of this mechanism, as it is sensitive to the non-Gaussian features in the seed fluctuations. To access this information, however, it is crucial to model the non-linear evolution of the CMB between the formation of the initial fluctuations and its observation, which results in the emergence of an intrinsic bispectrum. In this thesis we quantify the intrinsic bispectrum and compute the bias it induces on the primordial signal. To do so, we develop $\\text{SONG}$, an efficient code for solving the second-order Einstein-Boltzmann equations, and use it to estimate the CMB non-Gaussianity arising from the non-linear evolution of density perturbations. The full calculation involves ...

  17. Systematic Uncertainties In Constraining Dark Matter Annihilation From The Cosmic Microwave Background

    CERN Document Server

    Galli, Silvia; Valdes, Marcos; Iocco, Fabio

    2013-01-01

    Anisotropies of the cosmic microwave background (CMB) have proven to be a very powerful tool to constrain dark matter annihilation at the epoch of recombination. However, CMB constraints are currently derived using a number of reasonable but yet un-tested assumptions that could potentially lead to a misestimation of the true bounds. In this paper we examine the potential impact of these systematic effects. In particular, we separately study the propagation of the secondary particles produced by annihilation in two energy regimes; first following the shower from the initial particle energy to the keV scale, and then tracking the resulting secondary particles from this scale to the absorption of their energy as heat, ionization, or excitation of the medium. We improve both the high and low energy parts of the calculation, in particular finding that our more accurate treatment of losses to sub-10.2 eV photons produced by scattering of high-energy electrons weakens the constraints on particular DM annihilation mo...

  18. Measurements of the cosmic microwave background temperature at 1. 47 GHz

    Energy Technology Data Exchange (ETDEWEB)

    Bensadoun, M.J.

    1991-11-01

    A radiofrequency-gain total power radiometer measured the intensity of the cosmic microwave background (CMB) at a frequency of 1.47 GHz (20.4 cm wavelength) from White Mountain, California, in September 1988 and from the South Pole, Antarctica, in December 1989. The CMB thermodynamic temperature, TCMB, is 2.27 {plus minus} 0.25 K (68% C.L.) measured from White Mountain and 2.26 {plus minus} 0.21 K from the South Pole site. The combined result is 2.27 {plus minus} 0.19 K. The correction for galactic emission has been derived from scaled low-frequency maps and constitutes the main source, of error. The atmospheric signal is found by extrapolation from zenith scan measurements at higher frequencies. The result is consistent with previous low-frequency measurements, including a measurement at 1.41 GHz (Levin et al. 1988) made with an earlier version of this instrument. The result is {approximately}2.5 {sigma} ({approximately}l% probability) from the 2.74 {plus minus} 0.02,K global average CMB temperature.

  19. Anisotropy in the Cosmic Microwave Background at Degree Angular Scales Python V Results

    CERN Document Server

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

    1999-01-01

    Observations of the microwave sky using the Python telescope in its fifth season of operation at the Amundsen-Scott South Pole Station in Antarctica are presented. The system consists of a 0.75 m off-axis telescope instrumented with a HEMT amplifier-based radiometer having continuum sensitivity from 37-45 GHz in two frequency bands. With a 0.91 deg x 1.02 deg beam the instrument fully sampled 598 deg^2 of sky, including fields measured during the previous four seasons of Python observations. Interpreting the observed fluctuations as anisotropy in the cosmic microwave background, we place constraints on the angular power spectrum of fluctuations in eight multipole bands up to l ~ 260. The observed spectrum is consistent with both the COBE experiment and previous Python results. There is no significant contamination from known foregrounds. The results show a discernible rise in the angular power spectrum from large (l spectrum is not a simple linear rise but has a sharply increasing slope starting at l ~ 150.

  20. Data Reduction and Analysis of the Python V Cosmic Microwave Background Anisotropy Experiment

    CERN Document Server

    Coble, K A

    1999-01-01

    Observations of the microwave sky using the Python telescope in its fifth season of operation at the Amundsen-Scott South Pole Station in Antarctica are presented. The system consists of a 0.75 m off-axis telescope instrumented with a HEMT amplifier-based radiometer having continuum sensitivity from 37-45 GHz in two frequency bands. With a $0.91^{\\circ} \\times 1.02^{\\circ} $ beam the instrument fully sampled 598 deg$^2$ of sky, including fields measured during the previous four seasons of Python observations. Interpreting the observed fluctuations as anisotropy in the cosmic microwave background, we place constraints on the angular power spectrum of fluctuations in eight multipole bands up to $l \\sim 260$. The observed spectrum is consistent with both the COBE experiment and previous Python results. Total-power Wiener-filtered maps of the CMB are also presented. There is no significant contamination from known foregrounds. The results show a discernible rise in the angular power spectrum from large ($l \\sim 4...