Electronic properties of the pseudogap system (TaSe4)2I

The room temperature ``metallic'' properties of the quasi-one-dimensional charge density wave system (TaSe4)2I differ markedly from those expected of either a Fermi or a Luttinger Liquid. We discuss evidence for the simplest possible explanation of the observed behavior of (TaSe4)2I in its conducting phase - namely the existence of large quasi-static fluctuations of structural order, which however remain of finite extent above the charge density wave transition temperature. These fluctuations produce a pseudogap in the density of states. We compute the temperature dependence of the optical and DC conductivities of (TaSe4)2I in its conducting phase, the nature of its core hole spectra, and the NMR relaxation rate. Predictions for these quantities are made on the basis of a Lee, Rice and Anderson model. This model represents the simplest theory of a pseudogap, and gives satisfactory agreement with experiment in the cases where comparisons can be made. In contrast, the predictions of a strongly correlated (Luttinger Liquid) model appear to to contradict the data. The chief remaining discrepancy is that the gap appearing in transport quantities is less than that observed in photoemission. We discuss some possibilities for resolving this issue.Comment: 41 pages latex, 11 ps figures, uses IOP macro

Observations of Proper Motions and Annual Parallaxes of Pulsars

Almost all published data of pulsar proper motions and annual parallaxes observed by optical method, pulse arrival-time method, connected radio interferometric method and VLBI method for 46 pulsars including binary and millisecond pulsars are listed in a table. Scintillation velocities of 71 pulsars also including binary and millisecond pulsars are listed in another table

Formation of Galactic Center Magnetic Loops

A survey for the molecular clouds in the Galaxy with NANTEN mm telescope has discovered molecular loops in the Galactic center region. The loops show monotonic gradients of the line of sight velocity along the loops and the large velocity dispersions towards their foot points. It is suggested that these loops are explained in terms of the buoyant rise of magnetic loops due to the Parker instability. We have carried out global three-dimensional magneto-hydrodynamic simulations of the gas disk in the Galactic center. The gravitational potential is approximated by the axisymmetric potential proposed by Miyamoto & Nagai (1975). At the initial state, we assume a warm (~ 10^4 K) gas torus threaded by azimuthal magnetic fields. Self-gravity and radiative cooling of the gas are ignored. We found that buoyantly rising magnetic loops are formed above the differentially rotating, magnetically turbulent disk. By analyzing the results of global MHD simulations, we have identified individual loops, about 180 in the upper half of the disk, and studied their statistical properties such as their length, width, height, and velocity distributions along the loops. Typical length and height of a loop are 1kpc and 200pc, respectively. The line of sight velocity changes linearly along a loop and shows large dispersions around the foot-points. Numerical results indicate that loops emerge preferentially from the region where magnetic pressure is large. We argue that these properties are consistent with those of the molecular loops discovered by NANTEN.Comment: 16pages, 10figures. Accepted for publication in PASJ. Replace to higher resolution versio

Re-appearance of antiferromagnetic ordering with Zn and Ni substitution in La_{2-x}Sr_xCuO_4

The effects of nonmagnetic Zn and magnetic Ni substitution for Cu site on magnetism are studied by measurements of uniform magnetic susceptibility for lightly doped La_{2-x}Sr_xCu_{1-z}M_zO_4 (M=Zn or Ni) polycrystalline samples. For the parent x=0, Zn doping suppresses the N\'{e}el temperature T_N whereas Ni doping hardly changes T_N up to z=0.3. For the lightly doped samples with T_N~0, the Ni doping recovers T_N. For the superconducting samples, the Ni doping induces the superconductivity-to-antiferromagnetic transition (or crossover). All the heavily Ni doped samples indicate a spin glass behavior at \~15 K.Comment: 2 pages including 3 figures, to be published in Physica C (LT23, Hiroshima 2002

Aligned Molecular Clouds towards SS433 and L=348.5 degrees; Possible Evidence for Galactic "Vapor Trail" Created by Relativistic Jet

We have carried out a detailed analysis of the NANTEN 12CO(J=1-0) dataset in two large areas of ~25 square degrees towards SS433 (l~40 degree) and of ~18 square degrees towards l~348.5 degree, respectively. We have discovered two groups of remarkably aligned molecular clouds at |b|~1--5 degree in the two regions. In SS433, we have detected 10 clouds in total, which are well aligned nearly along the axis of the X-ray jet emanating from SS433. These clouds have similar line-of-sight velocities of 42--56 km s^-1 and the total projected length of the feature is ~300 pc, three times larger than that of the X-ray jet, at a distance of 3 kpc. Towards l~348.5 degree, we have detected four clouds named as MJG348.5 at line-of-sight velocities of -80 -- -95 km s^-1 in V_LSR, which also show alignment nearly perpendicular to the Galactic plane. The total length of the feature is ~400 pc at a kinematic distance of 6 kpc. In the both cases, the CO clouds are distributed at high galactic latitudes where such clouds are very rare. In addition, their alignments and coincidence in velocity should be even rarer, suggesting that they are physically associated. We tested a few possibilities to explain these clouds, including protostellar outflows, supershells, and interactions with energetic jets. Among them, a favorable scenario is that the interaction between relativistic jet and the interstellar medium induced the formation of molecular clouds over the last ~10^5-6 yrs. It is suggested that the timescale of the relativistic jet may be considerably larger, in the order of 10^5-6 yrs, than previously thought in SS433. The driving engine of the jet is obviously SS433 itself in SS433, although the engine is not yet identified in MJG348.5 among possible several candidates detected in the X-rays and TeV gamma rays.Comment: 29 pages, 10 figures, already published in PASJ, 2008,60, 71

A Detailed Observational Study of Molecular Loops 1 and 2 in the Galactic Center

Fukui et al. (2006) discovered two huge molecular loops in the Galactic center located in (l, b) ~ (355 deg-359 deg, 0 deg-2 deg) in a large velocity range of -180-40 km s^-1. Following the discovery, we present detailed observational properties of the two loops based on NANTEN 12CO(J=1-0) and 13CO(J=1-0) datasets at 10 pc resolution including a complete set of velocity channel distributions and comparisons with HI and dust emissions as well as with the other broad molecular features. We find new features on smaller scales in the loops including helical distributions in the loop tops and vertical spurs. The loops have counterparts of the HI gas indicating that the loops include atomic gas. The IRAS far infrared emission is also associated with the loops and was used to derive an X-factor of 0.7(+/-0.1){\times}10^20 cm^-2 (K km s^-1)^-1 to convert the 12CO intensity into the total molecular hydrogen column density. From the 12CO, 13CO, H I and dust datasets we estimated the total mass of loops 1 and 2 to be ~1.4 {\times} 106 Msun and ~1.9 {\times} 10^6 Msun, respectively, where the H I mass corresponds to ~10-20% of the total mass and the total kinetic energy of the two loops to be ~10^52 ergs. An analysis of the kinematics of the loops yields that the loops are rotating at ~47 km s-1 and expanding at ~141 km s^-1 at a radius of 670 pc from the center. Fukui et al. (2006) presented a model that the loops are created by the magnetic flotation due to the Parker instability with an estimated magnetic field strength of ~150 {\mu}G. We present comparisons with the recent numerical simulations of the magnetized nuclear disk by Machida et al. (2009) and Takahashi et al. (2009) and show that the theoretical results are in good agreements with the observations. The helical distributions also suggest that some magnetic instability plays a role similarly to the solar helical features.Comment: 40 pages, 22 figures, submitted to publication in PAS