A Radio Halo Found in the Hottest Known Cluster of Galaxies 1E0658-56

We report the detection of a diffuse radio halo source in the hottest known cluster of galaxies 1E0658-56 (RXJ0658-5557). The radio halo has a morphology similar to the X-ray emission from the hot intracluster medium. The detection of such a strong radio halo in such a hot cluster is further evidence to the link between X-ray temperature and cluster-wide radio halos. We describe a new model for the origin of cluster-wide radio halo sources involving a direct connection between the X-ray emitting thermal particles and the radio emitting relativistic particles.Comment: 6 pages, 5 postscript figues, Latex, to appear in proceedings of the Ringberg workshop on "Diffuse Thermal and Relativistic Plasma in Galaxy Clusters", April 1999, H. Boehringer, L. Feretti, P. Schuecker (eds.

Ultra-high resolution Fourier domain optical coherence tomography for resolving thin layers in painted works of art

While OCT has been applied to the non-invasive examination of the stratigraphy of paint layers in recent years, it has been recognized that the resolutions of commercially available OCT cannot compete in depth resolution with conventional microscopic examination of cross-sections of paint samples. It is necessary to achieve resolutions better than 3 microns to resolve the thinnest layers of paint and varnish. In this paper, we demonstrate a Fourier domain ultrahigh resolution OCT at 810nm with depth resolution of 1.8μm in air (or 1.2μm in varnish or paint)

Vacua and Exact Solutions in Lower-DD Limits of EGB

We consider the action principles that are the lower dimensional limits of the Einstein-Gauss-Bonnet gravity {\it via} the Kaluza-Klein route. We study the vacua and obtain some exact solutions. We find that the reality condition of the theories may select one vacuum over the other from the two vacua that typically arise in Einstein-Gauss-Bonnet gravity. We obtain exact black hole and cosmological solutions carrying scalar hair, including scalar hairy BTZ black holes with both mass and angular momentum turned on. We also discuss the holographic central charges in the asymptotic AdS backgrounds.Comment: Latex, 19 page

Bulk Entanglement Spectrum Reveals Quantum Criticality within a Topological State

A quantum phase transition is usually achieved by tuning physical parameters in a Hamiltonian at zero temperature. Here, we demonstrate that the ground state of a topological phase itself encodes critical properties of its transition to a trivial phase. To extract this information, we introduce a partition of the system into two subsystems both of which extend throughout the bulk in all directions. The resulting bulk entanglement spectrum has a low-lying part that resembles the excitation spectrum of a bulk Hamiltonian, which allows us to probe a topological phase transition from a single wavefunction by tuning either the geometry of the partition or the entanglement temperature. As an example, this remarkable correspondence between topological phase transition and entanglement criticality is rigorously established for integer quantum Hall states.Comment: 5 pages, 2 figures, 3 pages of Supplementary Materia

Non-invasive investigations of a wall painting using optical coherence tomography and hyperspectral imaging

Multispectral and hyperspectral imaging are efficient methods of measuring spectral reflectance at high spatial resolution. This non-invasive technique has been applied to the imaging of paintings over the last 20 years. PRISMS (Portable Remote Imaging System for Multispectral Scanning) was designed specifically for imaging wall paintings. Optical Coherence Tomography (OCT) is a low coherence interferometric technique capable of fast non-invasive imaging of subsurface microstructure. This paper shows the first application of in situ OCT imaging of a wall painting. The combination of PRISMS and OCT gives information on the varnish and paint layer structure, pigment identification, the state of degradation of the paint and varnish layers and informing curators on the painting schemes and techniques