Observational data on the large scale structure (LSS) of the Universe are used to establish an upper limit for the amplitude of the tensor mode marginalized over all other cosmological parameters within the class of adiabatic inflationary models. It is shown that the upper 1σ limit for the contribution of a tensor mode to the COBE DMR data is T/S < 1.

Two consecutive, distinct episodes of phase transition occurring during inflation may nucleate two generations of bubbles, one inside the other. We design a model of inflation that realizes this sequence and yields bubble spectra that are bimodal and tunable functions of phenomelogical parameters in turn combinations of microphysical parameters. We argue in favor of a tuning of the parameters such that the outer and earlier generation of bubbles becomes hundreds of Mpc/h in diameter (like the local Hubble bubbles of the literature) whereas the inner and later generation becomes tens of Mpc/h in diameter (like the observed large scale voids).

Recently, High-resolution algorithms such as the adaptive mesh refinement (AMR) method have been applied to cosmological simulations by several authors. However, the resolution of their INITIAL conditions is not high. We argue the need for cosmological high-resolution simulations to use a high-resolution initial condition or an initial condition including high-frequency components. Then we present the method of creating such initial condition, and estimate its computational cost.

We study a large-scale bulk motion of thin edge-on spiral galaxies from the RFGC catalogue using a multipole decomposition of velocity field. The quadrupole and octupole components are statistically significant. The first one corresponds to the Hubble flow anisotropy, the second one leads to decrease of modulus of dipole component due to the strong dipole-octupole interaction.

The radio wavelength luminosity of starburst galaxies correlates well with their star formation rates (Condon, 1992). Using this connection and three deep radio surveys, Haarsma and I constructed the global star formation history. Our results (see Haarsma et al., Ap. J., 2000 for details) show a steep increase from z = 0 to z = 1, matching calculations of the global SFR based on optical observations, when those observations have been corrected for the obscuration caused by dust. We note that our method requires no corrections for dust obscuration. We do, however, need to correct our results for radio emission from AGN. We do so using the extensive optical identifications available in these three fields.

We present the strategy and status of a gravitational lens search for multiple imaging with angular separations between 6″ and 15″ within the combined JVAS and CLASS dataset of ˜ 15000 flat-spectrum radio sources. Currently all but one lens candidate have been rejected.

This paper gives a summary of our rigorous, non-perturbative, Bayesian framework which enables one jointly to test Gaussianity and estimate the power spectrum of CMB anisotropies. A detailed and thorough presentation of this new technique has been given in Rocha et al. 2000. There we apply our method to Very Small Array (VSA) simulations based on signal Gaussianity, showing that out algorithm is indeed not biased.

We consider independent astrophysical constraints in the space of the density parameters Ωm of gravitating matter and ΩΛ of vacuum energy.

The Very Small Array (VSA) is a fourteen-element interferometer for sensitive measurement of the CMB anisotropies on scales of three degrees to ten arcminutes. The telescope is now observing on site in Tenerife after a period of commissioning, including the first map of the Sunyaev-Zel'dovich effect in the Coma cluster.

A distinguishing feature of the instrument is that each antenna in the array tracks quasi-independently, providing a characteristic fringe rate per baseline which can be used to reject many systematics. This effect has been optimised in the antenna array design.

Recent results on supernovae as standard candles (Riess et al. 1998; Perlmutter et al. 1999) and on CMB anisotropy (Lineweaver 1998) indicate that ΩM ≍ 0.3-0.4, Ωv ≍ 0.6-0.7, ΩM + Ωv ≍ 1. By definition, ΩM = ρM/ρcr, ΩV = ρv/ρcr, where ρM is the matter density, ρv is the vacuum density; the critical density ρcr = 3H2/8πG; H is the Hubble parameter, G is the gravitational constant. In the standard Friedmann-Lemaître cosmologies, these results seriously constrain the non-dimensional cosmological constant (as defined below): Δ ≫ 1, meaning that the Universe expands forever. If a scalar field is present, the future evolution may be different.

In the present paper, using a variety of N-body and gas codes, we study the large and small scale structures. Furthermore, we identify coherent objects at various threshold levels and calculate their planarity and filamentarity. The WEB theory is used to constrain the cosmological parameters of inflation-based Λ0 CDM models.

We studied the statistical methods for the estimation of the luminosity function (LF) of galaxies by Monte Carlo simulations. After examining the performance of these methods, we analyzed the photometric redshift data of the Hubble Deep Field prepared by Fernández-Soto et al. (1999). We also derived luminosity density ρL at B- and I-band. Our B-band estimation is roughly consistent with that of Sawicki, Lin, & Yee (1997), but a few times lower at 2.0 < z < 3.0. The evolution of ρL(I) is found to be less prominent.

We performed a mapping observation of the Sunyaev-Zel'dovich effect toward a galaxy cluster, CL0016+16, at 43 GHz using a newly developed 6-beam receiver installed in the Nobeyama 45-m telescope. The temperature decrement of the CMB was measured to be δT*A = −0.49 ± 0.06 mK at the center of the cluster. Fitting the isothermal, spherical-symmetrical β -model to the observed temperature decrement distribution, the S-Z effect at the center is inferred to be δTRJ(0) = −1.0 ± 0.1 mK at the Rayleigh-Jeans limit. This suggests that the Hubble constant is H0{q0 = 0.5} = 67+16−11 km s−1 Mpc−1.

We discuss the expected polarization of the Galactic foregrounds at the SPOrt experiment frequencies 22-90 GHz. We also consider the problem of foreground separation and perform an analysis to estimate their impact on the detection of a cosmological signal.

The three fields chosen for the first observations with the Very Small Array (VSA), a total area of ˜ 200 deg2, are being surveyed with the Ryle Telescope at 15 GHz. This is the only wide-field survey at a comparable radio frequency; its purpose is to investigate the source population and to define a catalogue of the foreground sources which must be monitored by the VSA during its observations. We present preliminary source counts.

Cosmological information is usually carried by, and extracted from massless spinning particles, “carriers of cosmological information”. The photon (spin 1-particle) is a good candidate representing one type of these carriers. Recently, the neutrino (spin 1/2-particle) entered the playground as another type. We expect, in the near future, that a third type of carriers, the graviton (spin 2-particle), to be used for extracting cosmological information. Two factors affect the properties of these carriers. The first is the source of the carrier. The second factor is the trajectory of the carrier, in the cosmic space, from its source to the receiver. The first factor implies the information carried, which reflect the properties of the source. The second factor represents the impact of the cosmic space-time on the properties of the carrier. So, information carried by these particles contain, a part connected to their sources, and another part related to the space-time through which these particles traveled.

The Jodrell-IAC CMB experiments at Teide Observatory, Tenerife consisting of switching radiometers operating at 10, 15 and 33 GHz, and a 33 GHz short baseline interferometer, have covered up to an area of 1 steradian at angular scales from 1° to 10° (l = 20 − 210). Sensitivities of 10μK per beam area have been reached for a combination the most sensitive experiments allowing a measure of the CMB fluctuation amplitude of 30±8μK using mapping techniques which fully exploit the whole data set. Attempts have been made to separate out galactic radio foregrounds and to place limits on a possible spinning dust contribution.

We present VLA and MERLIN monitoring data of the JVAS gravitational lens system B1030+074. The system was monitored with the VLA from February 1998 to October 1998 at 8.4-GHz during which the VLA was at its A, BnA and B configuration. The 47 epochs of observations have an average spacing of approximately 5 days. Ten MERLIN snapshots were obtained in the L-band (1.7 GHz) during the months of April, May and June 1998. Preliminary light curves of the two components of the lens system obtained from the VLA data indicate that during the period of the monitoring the A flux density showed a steady decrease. No changes are observed in the B light curve.

We consider solving the dark matter problem via a modified gravitational Lagrangian.

Pinning down the ages of high redshift galaxies is the most direct way of constraining the galaxy formation epoch. There has been a debate on the age of LBDS 53W091, a red galaxy at z=1.5. The discrepancy in the age estimates of various groups is due to the difference in the population synthesis model. However, there is generally a good agreement among popular models. Polishing the models and assessing their internal uncertainties are crucial in the analysis of high redshift galaxies.