17,143 research outputs found
An Unbiased Survey for Molecular Clouds in the Southern Galactic Warp
We have made an unbiased survey for molecular clouds in the Galactic Warp.
This survey, covering an area of 56 square degrees at l = 252 deg to 266 deg
and b = -5 deg to -1 deg, has revealed 70 molecular clouds, while only 6 clouds
were previously known in the region. The number of molecular clouds is, then,
an order of magnitude greater than previously known in this sector at R > 14.5
kpc. The mass of the clouds is in a range from 7.8x10(2) Mo to 8.4x10(4) Mo,
significantly less than the most massive giant molecular clouds in the inner
disk, ~10(6) Mo, while the cloud mass spectrum characterized by a power law is
basically similar to other parts of the Galaxy. The X factor, N(H2)/Wco(12CO),
derived from the molecular clouds in the Warp is estimated to be 3.5(+/-1.8)
times larger than that in the inner disk. The total molecular mass in the Warp
is estimated as 7.3x10(5) Mo, and total mass in the far-outer Galaxy (R > 14.5
kpc) can be estimated as 2x10(7) Mo. The spatial correlation between the CO and
HI distribution appears fairly good, and the mass of the molecular gas is about
1% of that of the atomic gas in the far-outer Galaxy. This ratio is similar to
that in the interarm but is ten times smaller than those of the spiral arms.
Only 6 of the 70 Warp clouds show signs of star formation at the IRAS
sensitivity and star formation efficiency for high-mass stars in the Warp is
found to be smaller than those in other molecular clouds in the Galaxy.Comment: 29 pages, including 12 (pages of) figures, accepted for PASJ, and
will be published in PASJ Vol.57, No.6. Tables and color-figures are
available on-line:
http://www.a.phys.nagoya-u.ac.jp/~masa/study/nakagawa_etal2005_warp.pd
Infrared behavior of the Faddeev-Popov operator in Coulomb gauge QCD
We calculate the eigenvalue distribution of the Faddeev-Popov operator in
Coulomb gauge QCD using quenched SU(3) lattice simulation. In the confinement
phase, the density of the low-lying eigenvalues increases with lattice volume,
and the confinement criterion is satisfied. Moreover, even in the deconfinement
phase, the behavior of the FP eigenvalue density is qualitatively the same as
in the confinement phase. This is consistent with the fact that the
color-Coulomb potential is not screened in the deconfined phase.Comment: 10 pages, 10 figure
Near-Solar-Circle Method for Determination of the Galactic Constants
We propose a method to determine the galactic constants R_0 (distance to the
Galactic Center) and V_0 (rotation velocity of the Sun) from measurements of
distances, radial velocities and proper motions of objects near the solar
circle. This is a modification of the solar-circle method to a more practical
observational method. We apply the method to determine R_0 using data from the
literature with known distances and radial velocities, and obtain R_0 = 7.54
+/- 0.77 kpc.Comment: 5 pages, 4 figures, accepted for PASJ (Vol. 63 No. 5
Scaling study of the gluon propagator in Coulomb gauge QCD on isotropic and anisotropic lattices
We calculate the transverse and time-time components of the instantaneous
gluon propagator in Coulomb gauge QCD by using an SU(3) quenched lattice
simulation on isotropic and anisotropic lattices. We find that the gluon
propagators suffer from strong discretization effects on the isotropic lattice;
on the other hand, those on the anisotropic lattices give a better scaling.
Moreover, on these two type of lattices the transverse parts are significantly
suppressed in the infrared region and have a turnover at about 500 [MeV]. The
high resolution to the temporal direction due to the anisotropy yields small
discretization errors for the time-time gluon propagators, which also show an
infrared enhancement as expected in the Gribov-Zwanziger confinement scenario.Comment: 29 pages, 18 figure
Thermal noise in half infinite mirrors with non-uniform loss: a slab of excess loss in a half infinite mirror
We calculate the thermal noise in half-infinite mirrors containing a layer of
arbitrary thickness and depth made of excessively lossy material but with the
same elastic material properties as the substrate. For the special case of a
thin lossy layer on the surface of the mirror, the excess noise scales as the
ratio of the coating loss to the substrate loss and as the ratio of the coating
thickness to the laser beam spot size. Assuming a silica substrate with a loss
function of 3x10-8 the coating loss must be less than 3x10-5 for a 6 cm spot
size and a 7 micrometers thick coating to avoid increasing the spectral density
of displacement noise by more than 10%. A similar number is obtained for
sapphire test masses.Comment: Passed LSC (internal) review. Submitted to Phys. Rev. D. (5/2001)
Replacement: Minor typo in Eq. 17 correcte
- …