Tales within Tales and Cutoffs within Cutoffs: What Sets the Mass Scale for Galaxies?

Please answer ``yes'' or ``no'': 1. Does the mass function for clusters of galaxies cut off exponentially? 2. Does the luminosity function for galaxies cut off exponentially? 3. Is the dependence of virial velocity on galaxy luminosity a power law? 4. Does the velocity function for galaxies cut off exponentially?Comment: 10 pages, no figures, contribution to the MPA/ESO/MPE/USM conference "Lighthouses of the Universe", Sunyaev et al. (eds.), ESO Astrophysics Symposia, Springer Verla

Correlated random fields in dielectric and spin glasses

Both orientational glasses and dipolar glasses possess an intrinsic random field, coming from the volume difference between impurity and host ions. We show this suppresses the glass transition, causing instead a crossover to the low $T$ phase. Moreover the random field is correlated with the inter-impurity interactions, and has a broad distribution. This leads to a peculiar variant of the Imry-Ma mechanism, with 'domains' of impurities oriented by a few frozen pairs. These domains are small: predictions of domain size are given for specific systems, and their possible experimental verification is outlined. In magnetic glasses in zero field the glass transition survives, because the random fields are disallowed by time-reversal symmetry; applying a magnetic field then generates random fields, and suppresses the spin glass transition.Comment: minor modifications, final versio

A Visual Guide to Planetary Microlensing

The microlensing technique has found 10 exoplanets to date and promises to discover more in the near future. While planetary transit light curves all show a familiar shape, planetary perturbations to microlensing light curves can manifest a wide variety of morphologies. We present a graphical guide that may be useful when understanding microlensing events showing planetary caustic perturbations.Comment: 2 pages, 1 figure, Submitted to the Proceedings of the IAU Symposium No. 27

HE 0435-1223: a wide separation quadruple QSO and gravitational lens

We report the discovery of a new gravitationally lensed QSO, at a redshift z = 1.689, with four QSO components in a cross-shaped arrangement around a bright galaxy. The maximum separation between images is 2.6 arcsec, enabling a reliable decomposition of the system. Three of the QSO components have g = 19.6, while component A is about 0.6 mag brighter. The four components have nearly identical colours, suggesting little if any dust extinction in the foreground galaxy. The lensing galaxy is prominent in the i band, weaker in r and not detected in g. Its spatial profile is that of an elliptical galaxy with a scale length of $\sim$ 12 kpc. Combining the measured colours and a mass model for the lens, we estimate a most likely redshift range of 0.3 < z < 0.4. Predicted time delays between the components are \la 10 days. The QSO shows evidence for variability, with total g band magnitudes of 17.89 and 17.71 for two epochs separated by $\sim 2$ months. However, the relative fluxes of the components did not change, indicating that the variations are intrinsic to the QSO rather than induced by microlensing.Comment: 7 pages, submitted to Astronomy and Astrophysic