A Morphological-type dependence in the mu_0-log(h) plane of Spiral galaxy disks

We present observational evidence for a galaxy `Type' dependence to the location of a spiral galaxy's disk parameters in the mu_0-log(h) (central disk surface-brightness - disk scale-length) plane. With a sample of ~40 Low Surface Brightness galaxies (both bulge- and disk-dominated) and ~80 High Surface Brightness galaxies, the early-type disk galaxies (<=Sc) tend to define a bright envelope in the mu_0-log(h) plane, while the late-type (>=Scd) spiral galaxies have, in general, smaller and fainter disks. Below the defining surface brightness threshold for a Low Surface Brightness galaxy (i.e. more than 1 mag fainter than the 21.65 B-mag arcsec^(-2) Freeman value), the early-type spiral galaxies have scale-lengths greater than 8-9 kpc, while the late-type spiral galaxies have smaller scale-lengths. All galaxies have been modelled with a seeing-convolved Sersic r^(1/n) bulge and exponential disk model. We show that the trend of decreasing bulge shape parameter (n) with increasing Hubble type and decreasing bulge-to-disk luminosity ratio, which has been observed amongst the High Surface Brightness galaxies, extends to the Low Surface Brightness galaxies, revealing a continuous range of structural parameters.Comment: To be published in ApJ. Inc. three two-part figure

HI Bright Galaxies in the Southern Zone of Avoidance

A blind survey for HI bright galaxies in the southern Zone of Avoidance, (212 deg < l < 36 deg; |b| < 5 deg), has been made with the 21 cm multibeam receiver on the Parkes 64 m radiotelescope. The survey, sensitive to normal spiral galaxies to a distance of about 40 Mpc and more nearby dwarfs, detected 110 galaxies. Of these, 67 have no counterparts in the NASA/IPAC Extragalactic Database. In general, the uncataloged galaxies lie behind thicker obscuration than do the cataloged objects. All of the newly-discovered galaxies have HI flux integrals more than an order of magnitude lower than the Circinus galaxy. The survey recovers the Puppis cluster and foreground group (Kraan-Korteweg & Huchtmeier 1992), and the Local Void remains empty. The HI mass function derived for the sample is satisfactorily fit by a Schechter function with parameters alpha = 1.51 +- 0.12, Phi* = 0.006 +- 0.003, and log M* = 9.7 +- 0.10.Comment: To appear in The Astronomical Journa

Loop expansion in Yang-Mills thermodynamics

We argue that a selfconsistent spatial coarse-graining, which involves interacting (anti)calorons of unit topological charge modulus, implies that real-time loop expansions of thermodynamical quantities in the deconfining phase of SU(2) and SU(3) Yang-Mills thermodynamics are, modulo 1PI resummations, determined by a finite number of connected bubble diagrams.Comment: 15 pages, 2 figures, v5: discussion of much more severely constrained nonplanar situation included in Sec.

Counting Yang-Mills Dyons with Index Theorems

We count the supersymmetric bound states of many distinct BPS monopoles in N=4 Yang-Mills theories and in pure N=2 Yang-Mills theories. The novelty here is that we work in generic Coulombic vacua where more than one adjoint Higgs fields are turned on. The number of purely magnetic bound states is again found to be consistent with the electromagnetic duality of the N=4 SU(n) theory, as expected. We also count dyons of generic electric charges, which correspond to 1/4 BPS dyons in N=4 theories and 1/2 BPS dyons in N=2 theories. Surprisingly, the degeneracy of dyons is typically much larger than would be accounted for by a single supermultiplet of appropriate angular momentum, implying many supermutiplets of the same charge and the same mass.Comment: 34 pages, 1 figure, LaTe

SN 1986J VLBI. The Evolution and Deceleration of the Complex Source and a Search for a Pulsar Nebula

We report on VLBI observations of supernova 1986J in the spiral galaxy NGC 891 at two new epochs, 1990 July and 1999 February, t=7.4 and 15.9 yr after the explosion, and on a comprehensive analysis of these and earlier observations from t~4 yr after the explosion date, which we estimate to be 1983.2 +/- 1.1. The source is a shell or composite, and continues to show a complex morphology with large brightness modulations along the ridge and with protrusions. The supernova is moderately to strongly decelerated. The average outer radius expands as t^(0.71 +/- 0.11), and the expansion velocity has slowed to 6000 km/s at t=15.9 yr from an extrapolated 20,000 km/s at t=0.25 yr. The structure changes significantly with time, showing that the evolution is not self-similar. The shell structure is best visible at the latest epoch, when the protrusions have diminished somewhat in prominence and a new, compact component has appeared. The radio spectrum shows a clear inversion above 10 GHz. This might be related to a pulsar nebula becoming visible through the debris of the explosion. The radio flux density between 1.5 and 23 GHz decreases strongly with time, with the flux density proportional to t^(-2.94 +/- 0.24) between t~15 to 19 yr. This decrease is much more rapid than that found in earlier measurements up to t~6 yr.Comment: 24 pages, 9 Figures, LaTeX Accepted for Publication in the Astrophysical Journa

Limit on the mass of a long-lived or stable gluino

We reinterpret the generic CDF charged massive particle limit to obtain a limit on the mass of a stable or long-lived gluino. Various sources of uncertainty are examined. The $R$-hadron spectrum and scattering cross sections are modeled based on known low-energy hadron physics and the resultant uncertainties are quantified and found to be small compared to uncertainties from the scale dependence of the NLO pQCD production cross sections. The largest uncertainty in the limit comes from the unknown squark mass: when the squark -- gluino mass splitting is small, we obtain a gluino mass limit of 407 GeV, while in the limit of heavy squarks the gluino mass limit is 397 GeV. For arbitrary (degenerate) squark masses, we obtain a lower limit of 322 GeV on the gluino mass. These limits apply for any gluino lifetime longer than $\sim 30$ ns, and are the most stringent limits for such a long-lived or stable gluino.Comment: 15 pages, 5 figures, accepted for publication in JHE

Calorons and localization of quark eigenvectors in lattice QCD

We analyze the localization properties for eigenvectors of the Dirac operator in quenched lattice QCD in the vicinity of the deconfinement phase transition. Studying the characteristic differences between the Z_3 sectors above the critical temperature T_c, we find indications for the presence of calorons.Comment: 4 pages, 4 figure