Signatures of the Milky Way's Dark Disk in Current and Future Experiments

In hierarchical structure formation models of disk galaxies, a dark matter disk forms as massive satellites are preferentially dragged into the disk-plane where they dissolve. Here, we quantify the importance of this dark disk for direct and indirect dark matter detection. The low velocity of the dark disk with respect to the Earth enhances detection rates in direct detection experiments at low recoil energy. For WIMP masses M_{WIMP} >~ 50 GeV, the detection rate increases by up to a factor of 3 in the 5 - 20 keV recoil energy range. Comparing this with rates at higher energy is sensitive to M_{WIMP}, providing stronger mass constraints particularly for M_{WIMP}>~100 GeV. The annual modulation signal is significantly boosted by the dark disk and the modulation phase is shifted by ~3 weeks relative to the dark halo. The variation of the observed phase with recoil energy determines M_{WIMP}, once the dark disk properties are fixed by future astronomical surveys. The low velocity of the particles in the dark disk with respect to the solar system significantly enhances the capture rate of WIMPs in the Sun, leading to an increased flux of neutrinos from the Sun which could be detected in current and future neutrino telescopes. The dark disk contribution to the muon flux from neutrino back conversion at the Earth is increased by a factor of ~5 compared to the SHM, for rho_d/rho_h=0.5.Comment: 5 pages, 7 figures, To appear in the proceedings of Identification of Dark Matter 2008 (IDM2008), Stockholm, 18-22 August 2008; corrected one referenc

Fractionalization and confinement in the U(1) and Z2Z_2 gauge theories of strongly correlated systems

Recently, we have elucidated the physics of electron fractionalization in strongly interacting electron systems using a $Z_2$ gauge theory formulation. Here we discuss the connection with the earlier U(1) gauge theory approaches based on the slave boson mean field theory. In particular, we identify the relationship between the holons and Spinons of the slave-boson theory and the true physical excitations of the fractionalized phases that are readily described in the $Z_2$ approach.Comment: 4 page

Dust-related interannual and intraseasonal variability of Martian climate using data assimilation

Data assimilation has been applied in several studies [Montabone et al., 2005; Lewis et al., 2005; Montabone et al., 2006a; Montabone et al., 2006b; Lewis et al., 2007; Wilson et al., 2008; Rogberg et al. 2010] as an effective tool with which to analyze spacecraft observations and phenomena (e.g., atmospheric tides, transient wave behavior, effects of clouds in the tropics, weather predictability, etc.) in the Martian atmosphere. A data assimilation scheme combined with a Martian Global Circulation Model (GCM) is able to provide a complete, balanced, four-dimensional solution consistent with observations. The GCM we use [Forget et al., 1999] combines a spectral dynamical solver and a tracer transport scheme developed in UK and Laboratoire de Météorologie Dynamique (LMD; Paris, France) physics package developed in collaboration with Oxford, The Open University and Instituto de Astrofisica de Andalucia (Granada, Spain). Here, we describe and discuss dust-related interannual and intraseasonal variability of the Martian climate. The results shown in this study come from a reanalysis using the Martian GCM with data assimilation scheme which assimilates Mars Global Surveyor/ Thermal Emission Spectrometer (MGS/TES) retrievals of temperature and column dust opacity. The detailed model setup was described by Montabone et al. [2006a], and the data assimilation scheme employed in this study was introduced in the work of Lewis et al. [2007]

Super-rotating jets in a re-analysis of the martian atmosphere

Strong westerly, prograde jets have been identified in the martian atmosphere between about 10–20 km altitude throughout much of the year in a Mars Global Circulation Model (MGCM) study [2]. The development of data assimilation techniques for Mars [3, 5] now permits the analysis of super-rotation in less highly idealized cases using an atmospheric reanalysis, as would be done for the Earth. This paper reviews recent atmospheric reanalyses, in order to validate previous modeling results, to quantify jet amplitudes and to diagnose possible mechanisms supplying angular momentum to the jets. [2] Lewis, S. R., and Read, P. L.: Equatorial jets in the dusty martian atmosphere, J. Geophys. Res., Vol. 108 (E4), 5034, pp. 1–15, 2003. [3] Lewis, S. R., Read, P. L., Conrath, B. J., Pearl, J. C., and Smith, M. D.: Assimilation of Thermal Emission Spectrometer atmospheric data during the Mars Global Surveyor aerobraking period, Icarus, Vol. 192 (2), pp. 327–347, 2007. [5] Montabone, L., Lewis, S. R., Read, P. L., Hinson, D. P., Validation of Martian meteorological data assimilation for MGS/TES using radio occultation measurements, Icarus Vol. 185 (1), pp. 113–132, 2006

Nitrification-denitrification in WSP: a mechanism for permanent nitrogen removal in maturation ponds

A pilot-scale primary maturation pond was spiked with 15N-labelled ammonia (15NH4Cl) and 15N labelled nitrite (Na15NO2), in order to improve current understanding of the dynamics of inorganic nitrogen transformations and removal in WSP systems. Stable isotope analysis of δ15N showed that nitrification could be considered as an intermediate step in WSP, which is masked by simultaneous denitrification, under conditions of low algal activity. Molecular microbiology analysis showed that denitrification can be considered a feasible mechanism for permanent nitrogen removal in WSP, which may be supported either by ammonia-oxidising bacteria (AOB) or by methanotrophs, in addition to nitrite-oxidising bacteria (NOB). However, the relative supremacy of the denitrification process over other nitrogen removal mechanisms (e.g., biological uptake) depends upon phytoplanktonic activity

Numerical study of spin quantum Hall transitions in superconductors with broken time-reversal symmetry

We present results of numerical studies of spin quantum Hall transitions in disordered superconductors, in which the pairing order parameter breaks time-reversal symmetry. We focus mainly on p-wave superconductors in which one of the spin components is conserved. The transport properties of the system are studied by numerically diagonalizing pairing Hamiltonians on a lattice, and by calculating the Chern and Thouless numbers of the quasiparticle states. We find that in the presence of disorder, (spin-)current carrying states exist only at discrete critical energies in the thermodynamic limit, and the spin-quantum Hall transition driven by an external Zeeman field has the same critical behavior as the usual integer quantum Hall transition of non-interacting electrons. These critical energies merge and disappear as disorder strength increases, in a manner similar to those in lattice models for integer quantum Hall transition.Comment: 9 pages, 9 figure

Correlation among Cirrus Ice Content, Water Vapor and Temperature in the TTL as Observed by CALIPSO and Aura-MLS

Water vapor in the tropical tropopause layer (TTL) has a local radiative cooling effect. As a source for ice in cirrus clouds, however, it can also indirectly produce infrared heating. Using NASA A-Train satellite measurements of CALIPSO and Aura/MLS we calculated the correlation of water vapor, ice water content and temperature in the TTL. We find that temperature strongly controls water vapor (correlation r =0.94) and cirrus clouds at 100 hPa (r = 0.91). Moreover we observe that the cirrus seasonal cycle is highly (r =0.9) anticorrelated with the water vapor variation in the TTL, showing higher cloud occurrence during December-January-February. We further investigate the anticorrelation on a regional scale and find that the strong anticorrelation occurs generally in the ITCZ (Intertropical Convergence Zone). The seasonal cycle of the cirrus ice water content is also highly anticorrelated to water vapor (r = 0.91) and our results support the hypothesis that the total water at 100 hPa is roughly constant. Temperature acts as a main regulator for balancing the partition between water vapor and cirrus clouds. Thus, to a large extent, the depleting water vapor in the TTL during DJF is a manifestation of cirrus formation

Intrinsic and extrinsic geometries of a tidally deformed black hole

A description of the event horizon of a perturbed Schwarzschild black hole is provided in terms of the intrinsic and extrinsic geometries of the null hypersurface. This description relies on a Gauss-Codazzi theory of null hypersurfaces embedded in spacetime, which extends the standard theory of spacelike and timelike hypersurfaces involving the first and second fundamental forms. We show that the intrinsic geometry of the event horizon is invariant under a reparameterization of the null generators, and that the extrinsic geometry depends on the parameterization. Stated differently, we show that while the extrinsic geometry depends on the choice of gauge, the intrinsic geometry is gauge invariant. We apply the formalism to solutions to the vacuum field equations that describe a tidally deformed black hole. In a first instance we consider a slowly-varying, quadrupolar tidal field imposed on the black hole, and in a second instance we examine the tide raised during a close parabolic encounter between the black hole and a small orbiting body.Comment: 27 pages, 4 figure