A Multi-Resolution Weak Lensing Mass Reconstruction Method

Motivated by the limitations encountered with the commonly used direct reconstruction techniques of producing mass maps, we have developed a multi-resolution maximum-likelihood reconstruction method for producing two dimensional mass maps using weak gravitational lensing data. To utilize all the shear information, we employ an iterative inverse method with a properly selected regularization coefficient which fits the deflection potential at the position of each galaxy. By producing mass maps with multiple resolutions in the different parts of the observed field, we can achieve a comparable level of signal to noise by increasing the resolution in regions of higher distortions or regions with an over-density of background galaxies. In addition, we are able to better study the sub-structure of the massive clusters at a resolution which is not attainable in the rest of the observed field. We apply our method to the simulated data and to a four square degree field obtained by the Deep Lens Survey.Comment: Preprint (30 pages, 10 figures), Submitted to Ap

Discovery of a Galaxy Cluster via Weak Lensing

We report the discovery of a cluster of galaxies via its weak gravitational lensing effect on background galaxies, the first spectroscopically confirmed cluster to be discovered through its gravitational effects rather than by its electromagnetic radiation. This fundamentally different selection mechanism promises to yield mass-selected, rather than baryon or photon-selected, samples of these important cosmological probes. We have confirmed this cluster with spectroscopic redshifts of fifteen members at z=0.276, with a velocity dispersion of 615 km/s. We use the tangential shear as a function of source photometric redshift to estimate the lens redshift independently and find z_l = 0.30 +- 0.08. The good agreement with the spectroscopy indicates that the redshift evolution of the mass function may be measurable from the imaging data alone in shear-selected surveys.Comment: revised version with minor changes, to appear in ApJ

The Landau gauge gluon and ghost propagator in the refined Gribov-Zwanziger framework in 3 dimensions

In previous works, we have constructed a refined version of the Gribov-Zwanziger action in 4 dimensions, by taking into account a novel dynamical effect. In this paper, we explore the 3-dimensional case. Analogously as in 4 dimensions, we obtain a ghost propagator behaving like $1/p^2$ in the infrared, while the gluon propagator reaches a finite nonvanishing value at zero momentum. Simultaneously, a clear violation of positivity by the gluon propagator is also found. This behaviour of the propagators turns out be in agreement with the recent numerical simulations.Comment: 26 pages, 16 .eps figures. v3: version accepted for publication in Phys Rev

An ASCA Study of the Heavy Element Distribution in Clusters of Galaxies

We perform a spatially resolved X-ray spectroscopic study of a set of 11 relaxed clusters of galaxies observed by the ROSAT/PSPC and ASCA/SIS. Using a method which corrects for the energy dependent effects of the ASCA PSF based on ROSAT images, we constrain the spatial distribution of Ne, Si, S and Fe in each cluster. Theoretical prescriptions for the chemical yields of Type Ia and II supernovae, then allow determination of the Fe enrichment from both types of supernovae as a function of radius within each cluster. Using optical measurements from the literature, we also determine the iron mass-to-light ratio (IMLR) separately for Fe synthesized in both types of supernovae. For clusters with the best photon statistics, we find that the total Fe abundance decreases significantly with radius, while the Si abundance is either flat or decreases less rapidly, resulting in an increasing Si/Fe ratio with radius. This result indicates a greater predominance of Type II SNe enrichment at large radii in clusters. We suggest that the high Si/Fe ratios in the outskirts of rich clusters may arise from enrichment by Type II SNe released to ICM via galactic star burst driven winds. Abridged.Comment: 17 pages, ApJ in press (Nov. 2000), a study of systematics is adde

A refinement of the Gribov-Zwanziger approach in the Landau gauge: infrared propagators in harmony with the lattice results

Recent lattice data have reported an infrared suppressed, positivity violating gluon propagator which is nonvanishing at zero momentum and a ghost propagator which is no longer enhanced. This paper discusses how to obtain analytical results which are in qualitative agreement with these lattice data within the Gribov-Zwanziger framework. This framework allows one to take into account effects related to the existence of gauge copies, by restricting the domain of integration in the path integral to the Gribov region. We elaborate to great extent on a previous short paper by presenting additional results, also confirmed by the numerical simulations. A detailed discussion on the soft breaking of the BRST symmetry arising in the Gribov-Zwanziger approach is provided.Comment: 38 pages, 9 figures, the content of section V has been extended and adapte

Weak Lensing Discovery and Tomography of a Cluster at z=0.68

We report the weak lensing discovery, spectroscopic confirmation, and weak lensing tomography of a massive cluster of galaxies at $z=0.68$, demonstrating that shear selection of clusters works at redshifts high enough to be cosmologically interesting. The mass estimate from weak lensing, $11.1 +- 2.8 x 10^{14} (r/Mpc)$ solar masses within projected radius r, agrees with that derived from the spectroscopy ($\sigma_v = 980 km s^{-1}$), and with the position of an arc which is likely to be a strongly lensed background galaxy. The redshift estimate from weak lensing tomography is consistent with the spectroscopy, demonstrating the feasibility of baryon-unbiased mass surveys. This tomographic technique will be able to roughly identify the redshifts of any dark clusters which may appear in shear-selected samples, up to z ~ 1.Comment: Final version. Substantially expanded from first version, including more detail, more figures, and more mass estimates, including an M/L estimate. Basic conclusions unchange

Smooth Bosonization as a Quantum Canonical Transformation

We consider a 1+1 dimensional field theory which contains both a complex fermion field and a real scalar field. We then construct a unitary operator that, by a similarity transformation, gives a continuum of equivalent theories which smoothly interpolate between the massive Thirring model and the sine-Gordon model. This provides an implementation of smooth bosonization proposed by Damgaard et al. as well as an example of a quantum canonical transformation for a quantum field theory.Comment: 20 pages, revte

On fermionic tilde conjugation rules and thermal bosonization. Hot and cold thermofields

A generalization of Ojima tilde conjugation rules is suggested, which reveals the coherent state properties of thermal vacuum state and is useful for the thermofield bosonization. The notion of hot and cold thermofields is introduced to distinguish different thermofield representations giving the correct normal form of thermofield solution for finite temperature Thirring model with correct renormalization and anticommutation properties.Comment: 13 page

Kinematics and Mass Profile of AWM 7

We have measured 492 redshifts (311 new) in the direction of the poor cluster AWM~7 and have identified 179 cluster members (73 new). We use two independent methods to derive a self-consistent mass profile, under the assumptions that the absorption-line galaxies are virialized and that they trace an underlying Navarro, Frenk & White (1997) dark matter profile: (1) we fit such an NFW profile to the radial distribution of galaxy positions and to the velocity dispersion profile; (2) we apply the virial mass estimator to the cluster. With these assumptions, the two independent mass estimates agree to \sim 15% within 1.7 h^{-1} Mpc, the radial extent of our data; we find an enclosed mass \sim (3+-0.5)\times 10^{14} h^{-1} M_\odot. The largest potential source of systematic error is the inclusion of young emission-line galaxies in the mass estimate. We investigate the behavior of the surface term correction to the virial mass estimator under several assumptions about the velocity anisotropy profile, still within the context of the NFW model, and remark on the sensitivity of derived mass profiles to outliers. We find that one must have data out to a large radius in order to determine the mass robustly, and that the surface term correction is unreliable at small radii.Comment: LaTeX, 5 tables, 7 figures, appeared as 2000 AJ 119 44; typos and Eq. 9 corrected; results are unaffecte

Caltech Faint Galaxy Redshift Survey X: A Redshift Survey in the Region of the Hubble Deep Field North

A redshift survey has been carried out in the region of the Hubble Deep Field North using the Low Resolution Imaging Spectrograph at the Keck Observatory. The resulting redshift catalog, which contains 671 entries, is a compendium of our own data together with published LRIS/Keck data. It is more than 92% complete for objects, irrespective of morphology, to $R = 24$ mag in the HDF itself and to $R = 23$ mag in the Flanking Fields within a diameter of 8 arcmin centered on the HDF, an unusually high completion for a magnitude limited survey performed with a large telescope. A median redshift $z = 1.0$ is reached at $R \sim 23.8$. Strong peaks in the redshift distribution, which arise when a group or poor cluster of galaxies intersect the area surveyed, can be identified to $z \sim 1.2$ in this dataset. More than 68% of the galaxies are members of these redshift peaks. In a few cases, closely spaced peaks in $z$ can be resolved into separate groups of galaxies that can be distinguished in both velocity and location on the sky. The radial separation of these peaks in the pencil-beam survey is consistent with a characteristic length scale for the their separation of $\approx$70 Mpc in our adopted cosmology ($h = 0.6, \Omega_M = 0.3$, $\Lambda = 0$). Strong galaxy clustering is in evidence at all epochs back to $z \le 1.1$. (abstract abridged)Comment: Accepted to the ApJ. This version contains all the figures and tables. 2 minor typos in table 2b correcte