118419164
Beyond the Linear-Order Relativistic Effect in Galaxy Clustering: Second-Order Gauge-Invariant Formalism
We present the second-order general relativistic description of the observed galaxy number density in a cosmological framework. The observed galaxy number density is affected by the volume and the source effects, both of which arise due to the mismatch between physical and observationally inferred quantities such as the redshift, the angular position, the volume, and the luminosity of the observed galaxies. These effects are computed to the second order in metric perturbations without choosing a gauge condition or adopting any restrictions on vector and tensor perturbations, extending the previous linear-order calculations. Paying particular attention to the second-order gauge transformation, we explicitly isolate unphysical gauge modes and construct second-order gauge-invariant variables. Moreover, by constructing second-order tetrads in the observer's rest frame, we clarify the relation between the physical and the parametrized photon wavevectors. Our second-order relativistic description will provide an essential tool for going beyond the power spectrum in the era of precision measurements of galaxy clustering. We discuss potential applications and extensions of the second-order relativistic description of galaxy clustering.
847496
All-sky analysis of the general relativistic galaxy power spectrum
We perform an all-sky analysis of the general relativistic galaxy power spectrum using the well-developed spherical Fourier decomposition. Spherical Fourier analysis expresses the observed galaxy fluctuation in terms of the spherical harmonics and spherical Bessel functions that are angular and radial eigenfunctions of the Helmholtz equation, providing a natural orthogonal basis for all-sky analysis of the large-scale mode measurements. Accounting for all the relativistic effects in galaxy clustering, we compute the spherical power spectrum and its covariance matrix and compare it to the standard three-dimensional power spectrum to establish a connection. The spherical power spectrum recovers the three-dimensional power spectrum at each wave number k with its angular dependence μk encoded in angular multipole l, and the contributions of the line-of-sight projection to galaxy clustering such as the gravitational lensing effect can be readily accommodated in the spherical Fourier analysis. A complete list of formulas for computing the relativistic spherical galaxy power spectrum is also presented.
14820775
THE END OF THE MACHO ERA: LIMITS ON HALO DARK MATTER FROM STELLAR HALO WIDE BINARIES
We simulate the evolution of halo wide binaries in the presence of the massive compact halo objects (MACHOs) and compare our results to the sample of wide binaries in a companion paper. The observed distribution is well fitted by a single power law for angular separations, 35 43 M☉ at the standard local halo density ρH. This all but removes the last permitted window for a full MACHO halo for masses M > 10-7.5 M☉.
119005540
Halo Structures of Gravitational Lens Galaxies
We explore the halo structure of four gravitational lenses with well-observed, thin Einstein rings. We find that the gravitational potentials are well described by ellipsoidal density distributions in the sense that the best-fit nonellipsoidal models have parameters consistent with their ellipsoidal counterparts. We find upper limits on the standard parameters for the deviation from an ellipse of |a_3/a_0|<0.023, 0.019, 0.037, and 0.035, and |a_4/a_0|<0.034, 0.041, 0.051, and 0.064 for SDSS J0924+0219, HE0435-1223, B1938+666, and PG1115+080, respectively. We find that the lens galaxies are at the centers of their dark matter halos, and obtain upper limits for the offset of each center of mass from the center of light of |Delta x|<0.004, 0.005, 0.009, and 0.005 arcsec, corresponding to 22, 29, 70, and 23 pc. These limits also exclude the possibility of any significant lopsidednessof the dark matter halos and set an upper limit of f_sat<sqrt(N)% on the mass fraction of massive substructures inside the Einstein ring if they are divided over N satellites. We also explore the properties of galaxies as substructures in groups for the lens PG1115+080, finding evidence for dark matter halos associated with the galaxies but no evidence for a clear distinction between satellite and central galaxies.
119340160
Big bang nucleosynthesis and cosmic microwave background constraints on the time variation of the Higgs vacuum expectation value
We derive constraints on the time variation of the Higgs vacuum expectation value $ $ through the effects on Big Bang nucleosynthesis (BBN) and the cosmic microwave background (CMB). In the former case, we include the (previously-neglected) effect of the change in the deuteron binding energy, which alters both the $^4$He and deuterium abundances significantly. We find that the current BBN limits on the relative change in \higgs are $-(0.6 - 0.7) \times 10^{-2} / < (1.5 - 2.0) \times 10^{-2}$, where the exact limits depend on the model we choose for the dependence of the deuteron binding energy on \higgs.The limits from the current CMB data are much weaker.
73543566
Complete treatment of galaxy two-point statistics: Gravitational lensing effects and redshift-space distortions
We present a coherent theoretical framework for computing gravitational lensing effects and redshift-space distortions in an inhomogeneous universe and investigate their impacts on galaxy two-point statistics. Adopt- ing the linearized Friedmann-Lemaˆ itre-Robertson-Walker metric, we derive the gravitational lensing and the generalized Sachs-Wolfe effects that include the weak lensing distortion, magnification, and time delay effects, and the redshift-space distortion, Sachs-Wolfe, and integ rated Sachs-Wolfe effects, respectively. Based on this framework, we first compute their effects on observed source fluctuations, separating them as two physically distinct origins: the volume effect that involves the chang e of volume and is always present in galaxy two-point statistics, and the source effect that depends on the intrin sic properties of source populations. Then we identify several terms that are ignored in the standard method, and we compute the observed galaxy two-point statistics, an ensemble average of all the combinations of the intrinsic source fluctuations and the additional contributions from the gravitational lensing and the generalized Sachs-Wolfe effects. This unified treatment of galaxy two- point statistics clarifies the relation of the gravitationa l lensing and the generalized Sachs-Wolfe effects to the metric perturbations and the underlying matter fluctuation s. For near future dark energy surveys, we compute additional contributions to the observed galaxy two-point statistics and analyze their impact on the anisotropic structure. Thorough theoretical modeling of galaxy two-point statistics would be not only necessary to analyze precision measurements from upcoming dark energy surveys, but also provide further discriminatory power in understanding the underlying physical mechanisms.
118941632
Search for periodic modulations of the solar neutrino flux in Super-Kamiokande-I
A search for periodic modulations of the solar neutrino flux was performed using the Super-Kamiokande-I data taken from May 31st, 1996 to July 15th, 2001. The detector's capability of measuring the exact time of events, combined with a relatively high yield of solar neutrino events, allows a search for short-time variations in the observed flux. We employed the Lomb test to look for periodic modulations of the observed solar neutrino flux. The obtained periodogram is consistent with statistical fluctuation and no significant periodicity was found.
12327360
Search for chameleon particles using a photon-regeneration technique.
We report the first results from the GammeV search for chameleon particles, which may be created via photon-photon interactions within a strong magnetic field. Chameleons are hypothesized scalar fields that could explain the dark energy problem. We implement a novel technique to create and trap the reflective particles within a jar and to detect them later via their afterglow as they slowly convert back into photons. These measurements provide the first experimental constraints on the couplings of chameleons to photons.
18442902
Tracking Performance of the Scintillating Fiber Detector in the K2K Experiment
The K2K long-baseline neutrino oscillation experiment uses a Scintillating Fiber Detector (SciFi) to reconstruct charged particles produced in neutrino interactions in the near detector. We describe the track reconstruction algorithm and the performance of the SciFi after 3 years of operation.
42455013
Results from the Cryogenic Dark Matter Search at Soudan Underground Laboratory
We present results from the Cryogenic Dark Matter Search at Soudan Underground Laboratory for two‐tower arrays of detector. Twelve detectors were operated from March 25 to August 8, 2004, or 74.5 detector live days. Within expected background, no statistically significant indication of a WIMP signal was observed. Based on this null observation and combined with our previous results, we exclude a spin‐averaged WIMP‐nucleon interaction cross section above 1.6 × 10−43 cm2 for Ge detectors, and 3 × 1042 cm2 for Si detectors, for a WIMP mass 60 GeV/c2 with 90%C.L. This result constrains parameter space of minimal supersymmetric standard models (MSSM) and starts to reach the parameter space of a constrained model (CMSSM).
18278613
Search for axionlike particles using a variable-baseline photon-regeneration technique.
We report the first results of the GammeV experiment, a search for milli-eV mass particles with axionlike couplings to two photons. The search is performed using a "light shining through a wall" technique where incident photons oscillate into new weakly interacting particles that are able to pass through the wall and subsequently regenerate back into detectable photons. The oscillation baseline of the apparatus is variable, thus allowing probes of different values of particle mass. We find no excess of events above background and are able to constrain the two-photon couplings of possible new scalar (pseudoscalar) particles to be less than 3.1x10;(-7) GeV-1 (3.5x10;(-7) GeV-1) in the limit of massless particles.