16668358
EXTENDING RECOVERY OF THE PRIMORDIAL MATTER POWER SPECTRUM
The shape of the primordial matter power spectrum encodes critical information on cosmological parameters. At large scales, in the linear regime, the observable galaxy power spectrum P obs(k) is expected to follow the shape of the linear matter power spectrum P lin(k), but on smaller scales the effects of nonlinearity and galaxy bias make the ratio P obs(k)/P lin(k) scale dependent. We develop a method that can extend the dynamic range of the primordial matter power spectrum recovery, taking full advantage of precision measurements on quasi-linear scales, by incorporating additional constraints on the galaxy halo occupation distribution (HOD) from the projected galaxy correlation function wp (rp ). We devise an analytic model to calculate observable galaxy power spectrum P obs(k) in real space and redshift space, given P lin(k) and HOD parameters, and we demonstrate its accuracy at the few percent level with tests against a suite of populated N-body simulations. Once HOD parameters are determined by fitting wp (rp ) measurements for a given cosmological model, galaxy bias is completely specified, and our analytic model predicts both the shape and normalization of P obs(k). Applying our method to the main galaxy redshift samples from the Sloan Digital Sky Survey (SDSS), we find that the real-space galaxy power spectrum follows the shape of the nonlinear matter power spectrum at the 1%-2% level up to k = 0.2 h Mpc–1 and that current observational uncertainties in HOD parameters leave only few percent uncertainties in our scale-dependent bias predictions up to k = 0.5 h Mpc–1. These uncertainties can be marginalized over in deriving cosmological parameter constraints, and they can be reduced by higher precision wp (rp ) measurements. When we apply our method to the SDSS luminous red galaxy (LRG) samples, we find that the linear bias approximation is accurate to 5% at k ≤ 0.08 h Mpc–1, but the strong scale dependence of LRG bias prevents the use of linear theory at k ≥ 0.08 h Mpc–1. Our HOD model prediction is in good agreement with the recent SDSS LRG power spectrum measurements at all measured scales (k ≤ 0.2 h Mpc–1), naturally explaining the observed shape of P obs(k) in the quasi-linear regime. The phenomenological "Q-model" prescription is a poor description of galaxy bias for the LRG samples, and it can lead to biased cosmological parameter estimates when measurements at k ≥ 0.1 h Mpc–1 are included in the analysis. We quantify the potential bias and constraints on cosmological parameters that arise from applying linear theory and Q-model fitting, and we demonstrate the utility of HOD modeling of high-precision measurements of P obs(k) on quasi-linear scales, which will be obtainable from the final SDSS data set.
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.
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.
14518995
Profiles of the resonance doublets formed in bipolar winds in symbiotic stars
We compute the profiles of resonance doublet lines (S1/2‐P1/2,3/2) formed in bipolar winds with velocity greater than the doublet separation in symbiotic stars. Particular attention has been paid to the doublet line ratio, where an essential role is played by the conversion of the short-wavelength component arising from the S1/2‐P3/2 transition into the long-wavelength component for the transition S1/2‐P1/2. We adopted a Monte Carlo technique and the Sobolev approximation. Our bipolar winds take the form of a cone and are characterized by the terminal wind velocity, the mass-loss rate and the opening angle of the cone. When an observer is in the polar direction and the Sobolev optical depth τSob � 1, we mainly obtain profiles with inverted flux line ratios, where the short-wavelength component is weaker than the long-wavelength component. When an observer is in the equatorial direction, we find that the profiles are characterized by two broad components, where the long-wavelength component is the broader and stronger of the two. We conclude that the profiles obtained in our model provide a qualitative understanding of the broad profiles and inverted intensity ratios of the doublets in symbiotic
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.
125983626
Photon asymmetry and neutral current effect in bremsstrahlung
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.