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.
51120946
Relativistic effects in galaxy clustering in a parametrized post-Friedmann universe
We explore the signatures of quintessence and modified gravity theories in the relativistic description of galaxy clustering within a parametrized post-Friedmann framework. For this purpose, we develop a calibration method to consistently account for horizon-scale effects in the linear parametrized post-Friedmann perturbations of minimally and nonminimally coupled scalar-tensor theories and test it against the full model-specific fluctuations. We further study the relativistic effects in galaxy clustering for the normal and self-accelerating branches of the Dvali-Gabadadze-Porrati braneworld model as well as for phenomenological modifications of gravity. We quantify the impact of modified gravity and dark energy models on galaxy clustering by computing the velocity-to-matter density ratio F , the velocity contribution R , and the potential contribution P and give an estimate of their detectability in future galaxy surveys. Our results show that, in general, the relativistic correction contains additional information on gravity and dark energy, which needs to be taken into account in consistent horizon-scale tests of departures from ΛCDM using the galaxy-density field.
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☉.
119269198
General Relativistic Description of the Observed Galaxy Power Spectrum: Do We Understand What We Measure?
We extend the general relativistic description of galaxy clustering developed in Yoo, Fitzpatrick, and Zaldarriaga (2009). For the first time we provide a fully general relativistic description of the observed matter power spectrum and the observed galaxy power spectrum with the linear bias ansatz. It is significantly different from the standard Newtonian description on large scales and especially its measurements on large scales can be misinterpreted as the detection of the primordial non-Gaussianity even in the absence thereof. The key difference in the observed galaxy power spectrum arises from the real-space matter fluctuation defined as the matter fluctuation at the hypersurface of the observed redshift. As opposed to the standard description, the shape of the observed galaxy power spectrum evolves in redshift, providing additional cosmological information. While the systematic errors in the standard Newtonian description are negligible in the current galaxy surveys at low redshift, correct general relativistic description is essential for understanding the galaxy power spectrum measurements on large scales in future surveys with redshift depth z ≥ 3. We discuss ways to improve the detection significance in the current galaxy surveys and comment on applications of our general relativistic formalism in future surveys.
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.
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.
122942501
CDMS EXPERIMENT: CURRENT STATUS AND FUTURE
We present the current status of the Cryogenic Dark Matter Search (CDMS). The five tower detector array, total 30 detectors, are running stable since October 2006. We have accumulated more than 900 kg-days of low background data. We also summarize the prospect of SuperCDMS project.
119668802
A study of short-time periodic variation of the 8 B solar neutrino flux at Super-Kamiokande
Super-Kamiokande(SK) is a real-time detector capable of measuring the exact time of solar neutrino events. This, combined with a relatively high yield of these events of roughly 15 per day, allows a search for short-time variations in the observed flux. Using all 1496 days of SK-I’s solar data, we looked for periodic variations of the observed solar neutrino flux, and found no significant periodicity. The Lomb test was used to find possible periodicities in the measured fluxes of 10 day long samples.
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).
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.
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.