Astronomy

Star Formation Properties in Barred Galaxies. III. Statistical Study of Bar-Driven Secular Evolution Using a Sample of Nearby Barred Spirals
Stellar bars are important internal drivers of secular evolution in disk galaxies. Using a sample of nearby spiral galaxies with weak and strong bars, we explore the relationships between the star formation feature and stellar bars in galaxies. We find that galaxies with weak bars tend coincide with low concentrical star formation activity, while those with strong bars show a large scatter in t...


The Linear Perturbation Theory of Reionization in Position-Space: Cosmological Radiative Transfer Along the Light-Cone
The linear perturbation theory of inhomogeneous reionization (LPTR) has beendeveloped as an analytical tool for predicting the global ionized fraction andlarge-scale power spectrum of ionized density fluctuations during reionization. In the original formulation of the LPTR, the ionization balance and radiativetransfer equations are linearized and solved in Fourier space. However, theLPTR's appr...
Unraveling the nature of Gravity through our clumpy Universe
We propose a new probe to test the nature of gravity at various redshiftsthrough large-scale cosmological observations. We use our void catalog,extracted from the Sloan Digital Sky Survey (SDSS, DR10), to trace thedistribution of matter along the lines of sight to SNe Ia that are selectedfrom the Union 2 catalog. We study the relation between SNe Ia luminosities andconvergence and also the pecu...


Imaging the transition between pre-planetary and planetary nebulae: Integral Field Spectroscopy of hot post-AGB stars with NIFS
We present 2 to 2.4 micron integral field spectroscopy of a sample of hotpost-AGB stars with early-B spectral types, using the NIFS instrument on GeminiNorth. These stars are just beginning to ionize their immediate environmentsand turn into planetary nebulae (PNe). We use molecular hydrogen emission linestogether with hydrogen and helium recombination lines to explore thedistribution of molecu...
Topological invariant quintessence
The issues of quintessence and cosmic acceleration can be discussed in theframework of $F(R, {cal G})$ theories of gravity where $R$ is the Riccicurvature scalar and ${cal G}$ is the Gauss-Bonnet topological invariant. Itis possible to show that such an approach exhausts all the curvature contentrelated to the Riemann tensor giving rise to a fully geometric approach to darkenergy.


Large scale distribution of ultra high energy cosmic rays detected at the Pierre Auger Observatory with zenith angles up to 80$^circ$
We present the results of an analysis of the large angular scale distributionof the arrival directions of cosmic rays with energy above 4 EeV detected atthe Pierre Auger Observatory including for the first time events with zenithangle between $60^circ$ and $80^circ$. We perform two Rayleigh analyses, onein the right ascension and one in the azimuth angle distributions, that aresensitive to modu...
Extreme luminosities in ejecta produced by intermittent outflows around rotating black holes
Extreme sources in the Transient Universe show evidence of relativisticoutflows from intermittent inner engines, such as cosmological gamma-raybursts. They probably derive from rotating back holes interacting withsurrounding matter. We show that these interactions are enhanced inverselyproportional to the duty cycle in advection of magnetic flux, as may apply athigh accretion rates. We demonstr...

Broad band turbulent spectra in gamma-ray burst light curves
Broad band power density spectra offer a window to understanding turbulentbehavior in the emission mechanism and, at the highest frequencies, in theputative inner engines powering long GRBs. We describe a chirp search methodwhich steps aside Fourier analysis for signal detection in the Poissonnoise-dominated 2 kHz sampled BeppoSAX light curves. An efficient numericalimplementation is described ...
Parameter estimation for binary neutron-star coalescences with realistic noise during the Advanced LIGO era
Advanced ground-based gravitational-wave (GW) detectors begin operationimminently. Their intended goal is not only to make the first direct detectionof GWs, but also to make inferences about the source systems. Binaryneutron-star mergers are among the most promising sources. We investigate theperformance of the parameter-estimation pipeline that will be used during thefirst observing run of the...

Revised Lens Model for the Multiply-Imaged Lensed Supernova, "SN Refsdal", in MACS J1149+2223
We present a revised lens model of MACS J1149+2223, in which the firstresolved multiply-imaged lensed supernova was discovered. The lens model isbased on the model of Johnson et al. (2014) with some modifications. We includemore lensing constraints from the host galaxy of the newly discoveredsupernova, and increase the flexibility of the model in order to betterreproduce the lensing signal in t...
Heavy neutralino relic abundance with Sommerfeld enhancements - a study of pMSSM scenarios
We present a detailed discussion of Sommerfeld enhancements in neutralinodark matter relic abundance calculations for several popular benchmarkscenarios in the general MSSM. Our analysis is focused on models with heavywino- and higgsino-like neutralino LSP and models interpolating between thesetwo scenarios. This work is the first phenomenological application of effectivefield theory methods th...

Non-relativistic pair annihilation of nearly mass degenerate neutralinos and charginos III. Computation of the Sommerfeld enhancements
This paper concludes the presentation of the non-relativistic effective fieldtheory formalism designed to calculate the radiative corrections that enhancethe pair-annihilation cross sections of slowly moving neutralinos and charginoswithin the general minimal supersymmetric standard model (MSSM). While papers Iand II focused on the computation of the tree-level annihilation rates thatfeed into ...
Towards a FPGA-controlled deep phase modulation interferometer
Deep phase modulation interferometry was proposed as a method to enhancehomodyne interferometers to work over many fringes. In this scheme, asinusoidal phase modulation is applied in one arm while the demodulation takesplace as a post-processing step. In this contribution we report on thedevelopment to implement this scheme in a fiber coupled interferometercontrolled by means of a FPGA, which i...
Fifty Years of Quasars: Physical Insights and Potential for Cosmology
Last year (2013) was more or less the 50th anniversary of the discovery ofquasars. It is an interesting time to review what we know (and don't know)about them both empirically and theoretically. These compact sources involvingline emitting plasma show extraordinary luminosities extending to one thousandtimes that of our Milky Way in emitting volumes of a few solar system diameters(bolometric lu...
Radiative ablation with two ionizing-fronts when opacity displays a sharp absorption edge
The interaction of a strong flux of photons with matter through anionizing-front (I-front) is an ubiquitous phenomenon in the context ofastrophysics and inertial confinement fusion (ICF) where intense sources ofradiation put matter into motion. When the opacity of the irradiated materialvaries continuously in the radiation spectral domain, only one single I-frontis formed. In contrast, as numer...