Flows to Schrodinger Geometries

We construct RG flow solutions interpolating AdS and Schrodinger geometries in Abelian Higgs models obtained from consistent reductions of type IIB supergravity and M-theory. We find that z=2 Schrodinger geometries can be realized at the minima of scalar potentials of these models, where a scalar charged under U(1) gauge symmetry obtains a nonzero vacuum expectation value. The RG flows are induced by an operator deformation of the dual CFT. The flows are captured by fake superpotentials of the theories.Comment: 19 pages, 5 figures, v2: typos corrected, references added, published version in PR

An astrometric facility for planetary detection on the space station

An Astrometric Telescope Facility (ATF) for planetary detection is being studied as a potential space station initial operating capability payload. The primary science objective of this mission is the detection and study of planetary systems around other stars. In addition, the facility will be capable of other astrometric measurements such as stellar motions of other galaxies and highly precise direct measurement of stellar distance within the Milky Way Galaxy. The results of a recently completed ATF preliminary systems definition study are summarized. Results of this study indicate that the preliminary concept for the facility is fully capable of meeting the science objective without the development of any new technologies. A simple straightforward operations approach was developed for the ATF. A real-time facility control is not normally required, but does maintain a near real-time ground monitoring capability for the facility and science data stream on a full-time basis. Facility observational sequences are normally loaded once a week. In addition, the preliminary system is designed to be fail-safe and single-fault tolerant. Routine interactions by the space station crew with the ATF will not be necessary, but onboard controls are provided for crew override as required for emergencies and maintenance

Nonlinear Evolution of Very Small Scale Cosmological Baryon Perturbations at Recombination

The evolution of baryon density perturbations on very small scales is investigated. In particular, the nonlinear growth induced by the radiation drag force from the shear velocity field on larger scales during the recombination epoch, which is originally proposed by Shaviv in 1998, is studied in detail. It is found that inclusion of the diffusion term which Shaviv neglected in his analysis results in rather mild growth whose growth rate is $\ll 100$ instead of enormous amplification $\sim 10^4$ of Shaviv's original claim since the diffusion suppresses the growth. The growth factor strongly depends on the amplitude of the large scale velocity field. The nonlinear growth mechanism is applied to density perturbations of general adiabatic cold dark matter (CDM) models. In these models, it has been found in the previous works that the baryon density perturbations are not completely erased by diffusion damping if there exists gravitational potential of CDM. With employing the perturbed rate equation which is derived in this paper, the nonlinear evolution of baryon density perturbations is investigated. It is found that: (1) The nonlinear growth is larger for smaller scales. This mechanism only affects the perturbations whose scales are smaller than $\sim 10^2M_\odot$, which are coincident with the stellar scales. (2) The maximum growth factors of baryon density fluctuations for various COBE normalized CDM models are typically less than factor 10 for $3-\sigma$ large scale velocity peaks. (3) The growth factor depends on $\Omega_{\rm b}$.Comment: 24 pages, 9 figures, submitted to Ap

Can Geometric Test Probe the Cosmic Equation of State ?

Feasibility of the geometric test as a probe of the cosmic equation of state of the dark energy is discussed assuming the future 2dF QSO sample. We examine sensitivity of the QSO two-point correlation functions, which are theoretically computed incorporating the light-cone effect and the redshift distortions, as well as the nonlinear effect, to a bias model whose evolution is phenomenologically parameterized. It is shown that the correlation functions are sensitive on a mean amplitude of the bias and not to the speed of the redshift evolution. We will also demonstrate that an optimistic geometric test could suffer from confusion that a signal from the cosmological model can be confused with that from a stochastic character of the bias.Comment: 11 pages, including 3 figures, accepted for publication in ApJ

Near Extremal Black Hole Entropy as Entanglement Entropy via AdS2/CFT1

We point out that the entropy of (near) extremal black holes can be interpreted as the entanglement entropy of dual conformal quantum mechanics via AdS2/CFT1. As an explicit example, we study near extremal BTZ black holes and derive this claim from AdS3/CFT2. We also analytically compute the entanglement entropy in the two dimensional CFT of a free Dirac fermion compactified on a circle at finite temperature. From this result, we clarify the relation between the thermal entropy and entanglement entropy, which is essential for the entanglement interpretation of black hole entropy.Comment: LaTeX, 32 pages, 7 figures; refinement in the organizatio

The cosmological light-cone effect on the power spectrum of galaxies and quasars in wide-field redshift surveys

We examine observational consequences of the cosmological light-cone effect on the power spectrum of the distribution of galaxies and quasars from upcoming redshift surveys. First we derive an expression for the power spectrum of cosmological objects in real space on a light cone, $P^{\rm LC}_{\rm R,lin}(k)$, which is exact in linear theory of density perturbations. Next we incorporate corrections for the nonlinear density evolution and redshift-space distortion in the formula in a phenomenological manner which is consistent with recent numerical simulations. On the basis of this formula, we predict the power spectrum of galaxies and quasars on the light cone for future redshift surveys taking account of the selection function properly. We demonstrate that this formula provides a reliable and useful method to compute the power spectrum on the light cone given an evolution model of bias.Comment: 18 pages, 3 figures, to be published in the Astrophysical Journa

High-field magnetization and magnetic phase transition in CeOs2Al10

We have studied the magnetization of CeOs2Al10 in high magnetic fields up to 55 T for H // a and constructed the magnetic phase diagram for H // a. The magnetization curve shows a concave H dependence below T_max \sim40 K which is higher than the transition temperature T_0 \sim29 K. The magnetic susceptibility along the a-axis shows a smooth and continuous decrease down to \sim20 K below T_max \sim40 K without showing an anomaly at T_0. From these two results, a Kondo singlet is formed below T_max and coexists with the antiferro magnetic order below T_0. We also propose that the larger suppression of the spin degrees of freedom along the a-axis than along the c-axis below T_max is associated with the origin of the antiferro magnetic component.Comment: 4 pages, 4 figures, to appear in Phys. Rev. B, Rapid Commu

Long-range order and low-energy magnetic excitations in CeRu2Al10

The nature of the unconventional ordered phase occurring in CeRu2Al10 below T0 = 27 K was investigated by neutron scattering. Powder diffraction patterns show clear superstructure peaks corresponding to forbidden (h + k)-odd reflections of the Cmcm space group. Inelastic neutron scattering experiments further reveal a pronounced magnetic excitation developing in the ordered phase at an energy of 8 meV.Comment: 5 pages; 4 figure

How to identify sex chromosomes and their turnover

Although sex is a fundamental component of eukaryotic reproduction, the genetic systems that control sex determination are highly variable. In many organisms the presence of sex chromosomes is associated with female or male development. Although certain groups possess stable and conserved sex chromosomes, others exhibit rapid sex chromosome evolution including transitions between male and female heterogamety, and turnover in the chromosome pair recruited to determine sex. These turnover events have important consequences for multiple facets of evolution, as sex chromosomes are predicted to play a central role in adaptation, sexual dimorphism, and speciation. However, our understanding of the processes driving the formation and turnover of new sex chromosome systems is limited, in part because we lack a complete understanding of inter‐specific variation in the mechanisms by which sex is determined. New bioinformatic methods are making it possible to identify and characterize sex chromosomes in a diverse array of non‐model species, rapidly filling in the numerous gaps in our knowledge of sex chromosome systems across the tree of life. In turn, this growing dataset is facilitating and fueling efforts to address many of the unanswered questions in sex chromosome evolution. Here, we synthesize the available bioinformatic approaches to produce a guide for characterizing sex chromosome system and identity simultaneously across clades of organisms. Furthermore, we survey our current understanding of the processes driving sex chromosome turnover, and highlight important avenues for future research