Massive stars (M ≥ 10M⊙) and supernova are found to be the possible sites for explosive thermonuclear burning. When a massive star collapses, shock waves moving through various convective zones produces explosive situations. The gravitational collapse of a helium exhausted core leads to violent instabilities. The reaction 12C(α, γ)16O is being studied under this condition. Recently it has been found that the coefficients in the semi-empirical mass formula are temperature dependent. Assuming the volume and surface binding to be effective, the nuclear masses, Q values, and reaction rates are calculated. Carbon alpha reaction is found to attain explosive proportion at the high temperature range considered here.

The gravitational lens CLASS B1608+656 is one of the most promising lens systems for the measurement of H0 on cosmological scales. The three independent time delays between the four lensed images have been measured, and the extended lensed optical emission holds the promise for a very well-constrained model. The published time delay measurements are based on the first season of VLA monitoring, in which the background source varied by only 5% in flux density. The small level of variation leads to relatively large uncertainties in the determination of the time delays (10-20%). Two more seasons of monitoring have now been completed and the source flux density has changed by ˜25% during that time. We present the results of the continued VLA monitoring and the resulting time-delay analysis. The new data have significantly reduced the uncertainties on the time delays and, hence, reduced the uncertainties on the resulting determination of H0 from this system.

We analyze the relations among the central gas density, core radius, and temperature of X-ray clusters by plotting the observational data in the three-dimensional (log ρgas,0, log rc, and log Tgas) space and find that the data lie on a ‘fundamental plane’. We discuss the implications of the plane.

The Red-Sequence Cluster Survey (RCS) is a 100 deg2 optical survey for high-redshift galaxy clusters. One of the goals of the survey is a measurement of Ωm and σ8 via the evolution of the mass spectrum of galaxy clusters. Herein we briefly describe how this will initially be done, and also demonstrate the eventual power of the RCS for this type of measurement by a qualitative analysis of the first 1/10th of the survey data.

We study the dynamics of first-order phase transition in the early Universe when it was 10 −50μs old with quarks and gluons condensing into hadrons. We look at the evolution of the Universe in small as well as large super cooling scenario.

A new H0 determination via the S-Z & X-ray route from cluster 0016+16 is presented. Potential sources of errors, in particular the effect of temperature profiles, are discussed.

We report significant associated clustering in the field of a z = 1.226 quasar from the Clowes-Campusano LQG in the form of both a factor ˜ 11 overdensity of I - K > 3.75 galaxies, and red sequences of 15-18 galaxies at I - K ⋍ 4.3, V - K ⋍ 6.9 indicative of a population of massive ellipticals at the quasar redshift. The quasar is located between two groups of these galaxies, with further clustering extending over 2-3 Mpc. A band of V - I < 1 galaxies bisects the two groups of red sequence galaxies, and we suggest that the merging of these two groups has triggered both this band of star-formation and the quasar.

We present a new ROBUST technique for extracting information from galaxy surveys which allows determination of cosmological parameters free of almost any model assumptions concerning the galaxy luminosity function and spatial clustering. We illustrate ROBUST by estimating H0 and the linear bias parameter, β, from recent redshift-distance data.

Recent studies have been revealing the properties of dwarf spheroidal galaxies (dSphs). Their low mass indicates that the dSphs may provide a clue to physical properties of the building blocks in the hierarchical structure formation. We select the Local Group dSphs as a sample. To obtain the information on the star formation history of dSphs, we investigate the relation between their metallicity and virial mass. According to our scenario, the star formation efficiency of the dSphs is low because of strong regulation. This is consistent with their high mass-to-light ratios. We also comment on the environmental effects on the dSphs.

The SMAC cluster sample (Hudson et al. 1999), with a depth of ˜ 12000km s-1, has a bulk velocity of ˜ 600 km s-1, with respect to the Cosmic Microwave Background (CMB) frame. Other surveys (Willick 1999, hereafter LP10k; Lauer & Postman 1994, hereafter ACIF) have also yielded large bulk motions on similarly large scales. Taken at face value, these results appear to be in conflict with bulk flows expected from favoured cosmological models. However, at the same time, other surveys (notably Dale et al. 1999, hereafter SC) have found rather small bulk motions on large scales. We have measured bulk flows from the above mentioned surveys plus SNIa (Riess et al. 1995) in a consistent way. The results are given in Table 1. The measurement errors are due to peculiar velocity errors. Note that these are the errors typically quoted. Based on these errors alone, there appears to be conflict between some of the surveys (e.g. SC vs SMAC).

The characteristics of the RATAN-600 radio telescope in multi-beam mode for CMBA observations are presented. First results of 8-element MMIC focal array testing are given.

In our ongoing work, we use high resolution cluster simulations to study gravitational lensing. These simulations have a softening length of 0.7 h-1 kpc and a particle mass of 4.68 × 107M⊙ (Springel 1999). Questions that can be addressed include the accuracy with which substructure on various scales can be recovered using the information from lensing. This is very important in determining the power of lensing in studying the evolution of cluster substructure as a function of redshift. We briefly consider how a weak lensing non-parametric reconstruction technique and the Map-statistic can be applied to the simulations.

Strongly correlated non-intrinsic variability between 5 and 8.5 GHz has been observed in one of the lensed images of the gravitational lens B1600+434. These non-intrinsic (i.e. ‘external’) variations are interpreted as radio-micro-lensing of relativistic μas-scale jet components in the source at a redshift of z=1.59 by massive compact objects in the halo of the edge-on disk lens galaxy at z=0.41. We shortly summarize these observations and discuss several new observational and theoretical programs to investigate this new phenomenon in more detail.

In this paper we report our analysis of the period-luminosity-shape of light curve (P-L-S) relation. The data we used came from LMC and SMC Cepheid light curves produced by OGLE-II microlensing survey. We used Principal Components Analysis of covariance matrix of the sets for Cepheids in LMC and SMC separately. Our calibrating set was bounded to long period classical Cepheids pulsating in fundamental mode. The results are used to derive a method for estimation of distances from light curve shape.

New calculations of the Galactic contribution to microwave background radiation anisotropies are carried out and a probable Galactic predominance over cosmological signals at large scales is explored for these frequencies. When we take into account a frequency-dependent contrast of molecular clouds with respect to the Galactic background of the diffuse interstellar medium, the anisotropic amplitude produced by Galactic dust is of the same order as that of the data from the observations. The frequency independence of anisotropies in the microwave range is not necessarily an argument against the Galactic predominance if we take into account an aditional rotational dust emission, for instance. This provides a basis for questioning the validity of considering negligible the Galactic contribution of the microwave background radiation anisotropies. Moreover, the size of the clouds is nearly coincident with that of the structures observed in the microwaves.

Cosmic Microwave Observations at 1° scales are extremely important on the understanding of modern Cosmology. At those angular scales the CMB power spectrum presents the first Doppler Peak. The position and amplitude of this peak provide strong constraints on cosmological parameters as H0 and Ω0. The JBO-IAC interferometer has observed those angular scales as well as the BOOMERANG and MAXIMA teams. The results from these groups show the existence of the first Doppler Peak. We present a detailed estimate of the galactic contribution to the JBO-IAC interferometer data set using data from the Tenerife and COSMOSOMAS experiments.

The test of the isotropy in the angular distribution of the gamma-ray bursts collected in BATSE Catalog (Meegan C. A. et al. 2000) is a test of cosmological principle itself, because the gamma-ray bursts are at cosmological distances. Several articles of the authors study this question (Balázs L. G., Mészáros A., & Horváth I., Astron. Astrophys., 339, 1, 1998; Balázs L. G., Mészáros A., Horváth I., & Vavrek R., Astron. Astrophys. Suppl., 138, 417, 1999; Mészáros A., Bagoly Z., & Vavrek R. Astron. Astrophys., 354, 1, 2000; Mészáros A., Bagoly Z., Horváth I., Balázs L.G. & Vavrek R. Astrophys. J., 539, 98, 2000). The final conclusion concerning the validity of isotropy is complicated both by instrumental effects and by the fact that there are three subgroups of gamma-ray bursts (“short”, “intermediate”, “long”; separation is done with respect to the duration of bursts). The long bursts are surely up to z ⋍ 4 (z is the redshift); for the remaining two subclasses the redshifts are unknown. The done tests of isotropy suggest (after the elimination of instrumental effects) the existence of anisotropy for the intermediate subclass on the confidence level > 95%. On the other hand, for the remaining two subclasses the situation is unclear; there is no unambiguous rejection of isotropy for them yet on the higher than 95% confidence level. If the bursts of intermediate subclass are at high z-s (say, at z > 0.1), then the validity of cosmological principle would be in serious doubt.

By assuming that the recently found cosmic acceleration is a genuine and ever present effect, we show that, the resultant modified Friedman model is free from the horizon and flatness problems; and there is no need to invoke the additional “inflationary” initial phase as a separate ingredient.

The probability that high-redshift quasars are gravitationally-lensed by intervening galaxies increases rapidly with the cosmological constant, ΩΛ0 (whilst being only weakly dependent on the density parameter, Ωm0), and the low number of lenses observed implies that ΩΛ0 ≲ 0.7 (e.g. Kochanek 1996). One of many uncertainties has been the (small) core radii of elliptical galaxies, which, at least naively, reduce their lensing cross-section. However, if ellipticals are normalised relative to their observed line-of-sight velocity dispersion, σ||, then increasing the core radius must result in an increased mass normalisation (specified by the assymptotic velocity dispersion, σ∞).

Gravitational lenses typically consist of either two or four images (doubles and quads) of the background source. However, it has been shown that gravitational lensing by transparent extended matter distributions should produce an odd number of images. An upper limit for the flux of the missing ‘odd image’ can be obtained using high sensitivity radio observations, such as 5GHz MERLIN (Multi-Element Radio Linked Interferometer Network) data. Limits on the ‘odd image’ flux can then be converted into an upper limit on the core radius of the lensing galaxy.