The Light-cone Effect on the Clustering Statistics in the Cosmological Redshift Space

We present a theoretical formalism to predict the two-point clustering statistics (the power spectrum and the two-point correlation function), simultaneously taking account of the linear velocity distortion, the nonlinear velocity distortion (finger-of-god), the cosmological redshift-space distortion and the light-cone effect. To demonstrate the importance of these effects in exploring the clustering of objects at high redshifts, we show several model predictions for magnitude-limited surveys of galaxies and quasars. This methodology provides a quantitative tool to confront theoretical models against the upcoming precision data on clustering in the universe.Comment: 8 pages, 3 figures, accepted for publication in PASJ (2000

Deciphering cosmological information from redshift surveys of high-z objects - the cosmological light-cone effect and redshift-space distortion -

The three-dimensional distribution of astronomical objects observed in redshift space significantly differs from the true distribution since the distance to each object cannot be determined by its redshift $z$ only; for $z \ll 1$ the peculiar velocity field contaminates the true recession velocity of the Hubble flow, while the true distance for objects at $z < 1$ sensitively depends on the (unknown and thus assumed) cosmological parameters. This hampers the effort to understand the true distribution of large-scale structure of the universe. In addition, all cosmological observations are carried out on a light-cone, the null hypersurface of an observer at $z=0$. This implies that their intrinsic properties and clustering statistics should change even within the survey volume. Therefore a proper comparison taking account of the light-cone effect is important to extract any cosmological information from redshift catalogues, especially for $z < 1$. We present recent theoretical development on the two effects -- the cosmological light-cone effect and the cosmological redshift-space distortion -- which should play key roles in observational cosmology in the 21st century.Comment: 28pages, 20 figures, minor revision to match the final version to appear in Progress of Theoretical Physics Supplement, vol. 133 (1999

Land mobile satellite propagation measurements in Japan using ETS-V satellite

Propagation characteristics of land mobile satellite communications channels have been investigated actively in recent years. Information of propagation characteristics associated with multipath fading and shadowing is required to design commercial land mobile satellite communications systems, including protocol and error correction method. CRL (Communications Research Laboratory) has carried out propagation measurements using the Engineering Test Satellite-V (ETS-V) at L band (1.5 GHz) through main roads in Japan by a medium gain antenna with an autotracking capability. This paper presents the propagation statistics obtained in this campaign

Adaptive data rate control TDMA systems as a rain attenuation compensation technique

Rainfall attenuation has a severe effect on signal strength and impairs communication links for future mobile and personal satellite communications using Ka-band and millimeter wave frequencies. As rain attenuation compensation techniques, several methods such as uplink power control, site diversity, and adaptive control of data rate or forward error correction have been proposed. In this paper, we propose a TDMA system that can compensate rain attenuation by adaptive control of transmission rates. To evaluate the performance of this TDMA terminal, we carried out three types of experiments: experiments using a Japanese CS-3 satellite with Ka-band transponders, in house IF loop-back experiments, and computer simulations. Experimental results show that this TDMA system has advantages over the conventional constant-rate TDMA systems, as resource sharing technique, in both bit error rate and total TDMA burst lengths required for transmitting given information

Low-Temperature Characteristics of an AlN/Diamond Surface Acoustic Wave Resonator

Phonons confined in mechanical resonators can be coupled to a variety of quantum systems and are expected to be applied to hybrid quantum systems. Diamond surface acoustic wave (SAW) devices are capable of high efficiency in phonon interaction with color centers in diamond. The temperature dependence of the quality factor is crucial for inferring the governing mechanism of coupling efficiency between phonons and color centers in diamond. In this paper, we report on the temperature dependence of the quality factor of an AlN/diamond SAW device from room temperature to 5 K. The temperature dependence of the quality factor and resonant frequency suggests that the mechanism of SAW dissipation in the AlN/diamond SAW resonator at 5 GHz is the phonon-phonon scattering in the Akheiser region, and that further cooling can be expected to improve the quality factor. This result provides a crucial guideline for the future design of AlN/diamond SAW devices.Comment: 10 pages, 5 figure