Edge-induced spin polarization in two-dimensional electron gas

We characterize the role of the spin-orbit coupling between electrons and the confining potential of the edge in nonequilibrium two-dimensional homogeneous electronic gas. We derive a simple analytical result for the magnitude of the current-induced spin polarization at the edge and prove that it is independent of the details of the confinement edge potential and the electronic density within realistic values of the parameters of the considered models. While the amplitude of the spin accumulation is comparable to the experimental values of extrinsic spin-Hall effect in similar samples, the spatial extent of edge-induced effect is restricted to the distances on the order of Fermi wavelength (similar to 10 nm)

Cosmological Brightness Distribution Fits of Gamma Ray Burst Sources

We discuss detailed fits of the BATSE and PVO gamma-ray burst peak-flux distributions with Friedman models taking into account possible density evolution and standard candle or power law luminosity functions. A chi-square analysis is used to estimate the goodness of the fits and we derive the significance level of limits on the density evolution and luminosity function parameters. Cosmological models provide a good fit over a range of parameter space which is physically reasonable.Comment: Ap.J. in press, uuencoded .ps file, 9 pages manuscript plus 5 figure

An assessment of the newest magnetar-SNR associations

Anomalous X-ray Pulsars and Soft-Gamma Repeaters groups are magnetar candidates featuring low characteristic ages ($\tau = {P\over{2 {\dot P}}}$). At least some of them they should still be associated with the remnants of the explosive events in which they were born, giving clues to the type of events leading to their birth and the physics behind the apparent high value of the magnetar magnetic fields. To explain the high values of $B$, a self-consistent picture of field growth also suggests that energy injection into the SNR is large and unavoidable, in contrast with the evolution of {\it conventional} SNR. This modified dynamics, in turn, has important implications for the proposed associations. We show that this scenario yields low ages for the new candidates CXOU J171405.7-381031/CTB 37B and XMMU J173203.3-344518/G353.6-0.7, and predicted values agree with recently found ${\dot P}$, giving support to the overall picture.Comment: Contributed talk to the ASTRONS 2010 Conference, Cesme, Turkey, Aug. 2-6 201

Analysis of the BATSE Continuous MER data

The CGRO/BATSE database includes many types of data such as the 16-channel continuous background or medium energy resolution burst data (CONT and MER data types). We have calculated some four hundred burst's medium energy resolution spectra and Principal Component Analysis has been applied. We found five components can describe GRBs' spectra.Comment: 4 pages, 2 figures, accepted in Nuovo Ciment

Strings in plane-fronted gravitational waves

Brinkmann's plane-fronted gravitational waves with parallel rays --~shortly pp-waves~-- are shown to provide, under suitable conditions, exact string vacua at all orders of the sigma-model perturbation expansion.Comment: 7 pages, no figure

Thermodynamics of black holes in finite boxes

We analyze the thermodynamical behavior of black holes in closed finite boxes. First the black hole mass evolution is analyzed in an initially empty box. Using the conservation of the energy and the Hawking evaporation flux, we deduce a minimal volume above which one black hole can loss all of its mass to the box, a result which agrees with the previous analysis made by Page. We then obtain analogous results using a box initially containing radiation, allowed to be absorbed by the black hole. The equilibrium times and masses are evaluated and their behavior discussed to highlight some interesting features arising. These results are generalized to $N$ black holes + thermal radiation. Using physically simple arguments, we prove that these black holes achieve the same equilibrium masses (even that the initial masses were different). The entropy of the system is used to obtain the dependence of the equilibrium mass on the box volume, number of black holes and the initial radiation. The equilibrium mass is shown to be proportional to a {\it positive} power law of the effective volume (contrary to naive expectations), a result explained in terms of the detailed features of the system. The effect of the reflection of the radiation on the box walls which comes back into the black hole is explicitly considered. All these results (some of them counter-intuitive) may be useful to formulate alternative problems in thermodynamic courses for graduate and advanced undergraduate students. A handful of them are suggested in the Appendix.Comment: RevTex file, 2 .ps figures. Submitted to AmJPhy