P-Cygni Type Lya from Starburst Galaxies

P-Cygni type Lya profiles exhibited in nearly half of starburst galaxies, both nearby and high-z, are believed to be formed by an expanding supershell surrounding a star-forming region. We apply the Monte Carlo code which was developed previously for static and plane-parallel medium to calculate the Lya line transfer in a supershell of neutral hydrogen which are expanding radially in a spherical bulk flow. We consider typical cases that the supershell has the Lya line-centre optical depth of $\tau_0=10^5-10^7$, a radial expansion velocity of $V_exp = 300 km/s, and the turbulence of b=40 km/s. We find that there appear a few emission peaks at the frequencies corresponding to (2N-1) V_exp, where the order of back scatterings N > 1. As V_exp -> b, the emergent profiles become similar to those for the static medium and the peaks are less prominent. We also investigate the effects of column density of the supershell on the emergent Lya profiles. We find that the number and the flux ratios of emission peaks are determined by interplay of$\tau_0$ and V_exp of the supershell. We discuss the effects of dust extinction and the implication of our works in relation to recent spectroscopic observations of starburst galaxies.Comment: 15 pages, 6 figures, submitted to MNRA

Rotation Correction Method Using Depth-Value Symmetry of Human Skeletal Joints for Single RGB-D Camera System

Most red-green-blue and depth (RGB-D) motion-recognition technologies employ both depth and RGB cameras to recognize a user\u27s body. However, motion-recognition solutions using a single RGB-D camera struggle with rotation recognition depending on the device-user distance and field-of-view. This paper proposes a near-real-time rotational-coordinate-correction method that rectifies a depth error unique Microsoft Kinect by using the symmetry of the depth coordinates of the human body. The proposed method is most effective within 2 m, a key range in which the unique depth error of Kinect occurs, and is anticipated to be utilized in applications requiring low cost and fast installation. It could also be useful in areas such as media art that involve unspecified users because it does not require a learning phase. Experimental results indicate that the proposed method has an accuracy of 85.38%, which is approximately 12% higher than that of the reference installation method

Massless Rotating Spacetimes in Four-Dimensional Horava Gravity

We study a particular exact solution for rotating spacetimes in four-dimensional Horava gravity, which has been proposed as a renormalizable gravity model without the ghost problem. We show that the massless Kerr spacetime or the massless Kerr-(A)dS spacetime in Einstein gravity is an exact solution in four-dimensional Horava for an arbitrary IR Lorentz-violation parameter lambda, but with an appropriate cosmological constant. In particular, for the massless topological Kerr-AdS black hole solution with the hyperbolic horizon topology or the massless Kerr-dS cosmological solution with the spherical horizon topology, there exist the ergosphere and the non-vanishing Hawking temperature, which imply the existence of negative mass black holes as well as positive mass spacetimes, by losing its mass from the massless ones via the Hawking radiation or Penrose process in the ergosphere.Comment: 10 pages, 3 figure

Generic features of the cosmological evolution of density parameters

The evolution of various energy components with dark energy was examined. Recently many non-standard gravity models were suggested to explain the current observational data showing an accelerating phase since the recent past. All suggested models should mimic ΛCDM somehow, especially from the near past to the current epoch. However, most of them do not try to explain or predict what happens if their model were extended to the far past and/or the past. In this paper we want to address this point by analyzing the critical points of the evolution equations and their stability. Standard ΛCDM gives three critical points, radiation dominated, matter dominated, and cosmological constant dominated. Furthermore, the radiation-dominated point corresponds to the past stable point, the matterdominated point to the saddle point, and the cosmological-constant–dominated point to the future stable point. This means that this model predicts that the universe starts from radiation domination then passes through a matter-dominated era and finally evolves into a cosmological-constant–dominated era, that is, the future de Sitter phase. We applied these creteria to few f(R) gravity models to determine viable parameter ranges