arXiv subjects

M. Sawicki

Publications and source records attributed to M. Sawicki.

95 records · Page 6Linked to original sources

arXiv1998

The Omega_M-Omega_Lambda Constraint from CNOC Clusters

The CNOC redshift survey of galaxy clusters measures Omega_M from Omega_e(z)= M/L x j/ρ_c which can be applied on a cluster-by-cluster basis. The mass-to-light ratios, M/L, are estimated from rich galaxy clusters, corrected to the field population over the 0.18 to 0.55 redshift range. Since the luminosity density depends on cosmological volumes, the resulting Omega_e(z) has a strong dependence on cosmology which allows us to place the results in the Omega_M-Omega_Lambda plane. The resulting Omega_M declines if Omega_Lambda>0 and we find that Omega_Lambda<1.5.

astro-ph↗

arXiv1997

Results on Galaxy Evolution from the CNOC2 Field Galaxy Redshift Survey

The CNOC2 Field Galaxy Redshift Survey presently contains some 5000 galaxy redshifts, plus extensive UBgRI photometry, and is the largest galaxy sample at moderate redshifts 0.1 < z < 0.6. Here we present some preliminary results on the galaxy luminosity function (LF) and its redshift evolution, using a sample of R < 21.5 CNOC2 galaxies, subdivided into early, intermediate, and late types based on their B-R colors relative to non-evolving galaxy models. We find a significant steepening in the faint-end slope alpha of the LF as one proceeds from early to late types. Also, for all galaxy types we find a rate of M* evolution consistent with that from passively evolving galaxy models. Finally, late-type galaxies show positive density evolution with redshift, in contrast to negative or no density evolution for earlier types.

astro-ph↗

arXiv1997

Interaction effects at the magnetic-field induced metal-insulator transition in Si/SiGe superlattices

A metal-insulator transition was induced by in-plane magnetic fields up to 27 T in homogeneously Sb-doped Si/SiGe superlattice structures. The localisation is not observed for perpendicular magnetic fields. A comparison with magnetoconductivity investigations in the weakly localised regime shows that the delocalising effect originates from the interaction-induced spin-triplet term in the particle-hole diffusion channel. It is expected that this term, possibly together with the singlet particle-particle contribution, is of general importance in disordered n-type Si bulk and heterostructures.

cond-mat.mes-hall↗

arXiv1997

Omega_M and the CNOC Surveys

The CNOC1 cluster survey measures Omega_M via Oort's method, Omega_M= M/L x j/rho_c, where M/L is the field mass-to-light ratio, j is the field luminosity density and rho_c is the closure density. A wide range of potential systematic effects are explicitly controlled by independently deriving the mean cluster mass profile (finding good agreement with theoretical predictions), the cluster light profile, the redshift evolution of both cluster and field galaxies, the differential evolution between the two, and the field and cluster efficiencies for the conversion of baryons into galaxies. We conclude that Omega_M=0.19+/-0.06 where the errors are objectively evaluated via resampling methods. The redshift evolution of the numbers of clusters per unit co-moving volume over the 0< z < 0.6 range is found to be very slow, as is required for consistency with a low density universe. The evolution of galaxy clustering in the field is compatible with a low density universe, and strongly disfavors models of galaxy evolution that associate low density halos with individual galaxies.

astro-ph↗

arXiv1993

Parity Transformation in the Front Form

By considering the parity-transformation properties of the $(1/2,\,0)$ and $(0,\,1/2)$ fields in the {\it front form} we find ourselves forced to study the front-form evolution both along $x^+$ and $x^-$ directions. As a by product, we find that half of the dynamical degrees of freedom of a full theory live on the $x^+=0$ surface and the other half on the $x^-=0$ surface. Elsewhere, Jacob shows how these results are required to build a satisfactory, and internally consistent, front-form quantum field theory.

hep-th↗