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介绍 : In order to obtain a fast magnetic reconnection we need some mechanisms that enhance the effective magnetic diffusivity. Turbulence is considered to be one of such candidates. Focusing on the turbulence effects in the mean magnetic - field evolution, we construct a system of turbulence model, where the tu rbulent evolution is solved through the transport equations of several turbulent statistical quantities, in addition to the mean - field equations for the density, momentum, and energy. Numerical results showed that a slow laminar - like reconnection for very weak turbulence, and just a turbulent diffusion of the mean magnetic field (no fast reconnection) for too much turbulence. Another interesting point is the role of the cross helicity (velocity -- magnetic - field correlation). The dynamic balance between the t ransport enhancement and suppression due to turbulence, the turbulent cross helicity contributes to localization of the effective magnetic diffusivity, leading to a fast reconnection.

介绍 : Large amount of important scientific information is contained in sub-millimeter (submm) and far infrared (FIR) wavelength: e.g. dusty galaxies, clusters and star formation etc, but it is also one of the least explored field in astronomy due to technology difficulties. In the past ten years, a lot of efforts have put on sub-millimeter and millimeter (mm) wave astronomical instrument/telescope development. Number of detectors is key feature of such instrument and is the direction we pursue. Future telescope will require as many as hundreds of thousands of detectors or more to meet the telescope fields of view, scan speed and resolution ability. The large pixel count is benefit from revolution of multiplexable detectors, where we use kinetic inductance detector (KIDs) array. This talk presents the development of KIDs based instruments include detector wafer design and readout electronics, which together made currently largest detector counts of submm/mm imaging array (2304) possible and attractive. The work of this talk has been implemented as the MUltiwavelength Sub/millimeter Inductance Camera (MUSIC), a new instrument for the Caltech Submillimeter Observatory (CSO).

介绍 : We studied the large-scale distribution of the Lyman-Alpha Emitters at z=3.1 over the 1.4 deg^2 area at SSA22 field that involves one of the most conspicuous high-redshift "protocluster", or the high-density peak of star-forming galaxies known so far, at z=3.09. Using Subaru Telescope, we have detected ~1500 emitters at z=3.1 including ~100 Lyman Alpha Blobs which are the extended Lyman Alpha emission halos. The "superstructre" of the emitters distributed over ~200 Mpc comoving scale contains the protocluster (density peak), its surrounding ~30Mpc-scale "belt-like" high density region whose significance is also very high (overdensity is 1.13±0.01, still ~10σ of the expected CDM fluctuation at such large scale), as well as the very under-dense “voids” of the emitters. We studied the distributions of the Ly Alpha luminosity, size, and equivalent width over the wide-range of density environment as well as the properties of the Ly Alpha Blobs in the field. We have also obtained deep NIR image and spectra of the galaxies in the z=3.09 protocluster to study the properties of the massive galaxies and their activity. We have indeed detected the density peak of the K-band selected galaxies whose position coincides with the local peak of the LyAlpha emitters. Compared with the Coma cluster, ~30-40% of the stellar mass already formed in the protocluster. The massive galaxies are dominated by very red objects, little overlap with LBG and LyAlpha emitters, ~50% of them are quiescent (passively-evolving) spectra while many of the rest have very active and dusty star-formation activity. We're witnessing the formation of the cluster massive galaxies there.