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July - December 2014

A Data-driven Approach for Retrieving Temperatures and Abundances in Brown Dwarf Atmospheres

Line, Michael R.; Fortney, Jonathan J.; Marley, Mark S.; Sorahana, Satoko

Brown dwarf spectra contain a wealth of information about their molecular abundances, temperature structure, and gravity. We present a new data driven retrieval approach, previously used in planetary atmosphere studies, to extract the molecular abun ...
Waiting Time Distribution of Solar Energetic Particle Events Modeled with a Non-stationary Poisson Process

Li, C.; Zhong, S. J.; Wang, L.; Su, W.; Fang, C.

We present a study of the waiting time distributions (WTDs) of solar energetic particle (SEP) events observed with the spacecraft WIND and GOES. The WTDs of both solar electron events (SEEs) and solar proton events (SPEs) display a power-law tail of ...
Transit and Radial Velocity Survey Efficiency Comparison for a Habitable Zone Earth

Burke, Christopher J.; McCullough, P. R.

Transit and radial velocity searches are two techniques for identifying nearby extrasolar planets to Earth that transit bright stars. Identifying a robust sample of these exoplanets around bright stars for detailed atmospheric characterization is a ...
The strongest gravitational lenses. IV. The order statistics of the largest Einstein radii with cluster mergers

Redlich, M.; Waizmann, J.-C.; Bartelmann, M.

Based on techniques developed in the previous papers of this series, we investigate the impact of galaxy-cluster mergers on the order statistics of the largest Einstein radii. We show that the inclusion of mergers significantly shifts the extreme va ...
Improving cosmic string network simulations

Hindmarsh, Mark; Rummukainen, Kari; Tenkanen, Tuomas V. I.; Weir, David J.

In real-time lattice simulations of cosmic strings in the Abelian Higgs model, the broken translational invariance introduces lattice artifacts; relativistic strings therefore decelerate and radiate. We introduce two different methods to construct a ...
Exploring the role of the Sun's motion in terrestrial comet impacts

Feng, F.; Bailer-Jones, C. A. L.

The cratering record on the Earth and Moon shows that our planet has been exposed to high velocity impacts for much or all of its existence. Some of these craters were produced by the impact of long-period comets (LPCs). These probably originated in ...
Reionization and CMB non-Gaussianity

Munshi, D.; Corasaniti, P. S.; Coles, P.; Heavens, A.; Pandolfi, S.

We show how cross-correlating a high-redshift external tracer field, such as the 21-cm neutral hydrogen distribution and product maps involving cosmic microwave background (CMB) temperature and polarization fields, that probe mixed bispectrum involv ...
The `amplitude' parameter of gamma-ray bursts and its implications for GRB classification

Lü, Hou-Jun; Zhang, Bing; Liang, En-Wei; Zhang, Bin-Bin; Sakamoto, Takanori

Traditionally, gamma-ray bursts (GRBs) are classified in the T90-hardness ratio two-dimensional plane into long/soft and short/hard GRBs. In this paper, we suggest to add the `amplitude' of GRB prompt emission as the third dimension as a complementa ...
Evidence for substructure in Ursa Minor dwarf spheroidal galaxy using a Bayesian object detection method

Pace, Andrew B.; Martinez, Gregory D.; Kaplinghat, Manoj; Muñoz, Ricardo R.

We present a method for identifying localized secondary populations in stellar velocity data using Bayesian statistical techniques. We apply this method to the dwarf spheroidal galaxy Ursa Minor and find two secondary objects in this satellite of th ...
Dark energy model selection with current and future data

Debono, Ivan

The main goal of the next generation of weak-lensing probes is to constrain cosmological parameters by measuring the mass distribution and geometry of the low-redshift Universe and thus to test the concordance model of cosmology. A future all-sky to ...
ALICCE: Atomic Lines Calibration using the Cross-Entropy Algorithm

Martins, Lucimara P.; Coelho, Paula; Caproni, Anderson; Vitoriano, Roberto

Atomic line opacities play a crucial role in stellar astrophysics. They strongly modify the radiative transfer in stars, therefore, impacting their physical structure. Ultimately, most of our knowledge of stellar population systems (stars, clusters, ...
Synthesizing Exoplanet Demographics from Radial Velocity and Microlensing Surveys. II. The Frequency of Planets Orbiting M Dwarfs

Clanton, Christian; Gaudi, B. Scott

In contrast to radial velocity (RV) surveys, results from microlensing surveys indicate that giant planets with masses greater than the critical mass for core accretion (~0.1 M Jup) are relatively common around low-mass stars. Using the methodology ...
Synthesizing Exoplanet Demographics from Radial Velocity and Microlensing Surveys. I. Methodology

Clanton, Christian; Gaudi, B. Scott

Motivated by the order of magnitude difference in the frequency of giant planets orbiting M dwarfs inferred by microlensing and radial velocity (RV) surveys, we present a method for comparing the statistical constraints on exoplanet demographics inf ...
A Formal Method for Identifying Distinct States of Variability in Time-varying Sources: Sgr A* as an Example

Meyer, L.; Witzel, G.; Longstaff, F. A.; Ghez, A. M.

Continuously time variable sources are often characterized by their power spectral density and flux distribution. These quantities can undergo dramatic changes over time if the underlying physical processes change. However, some changes can be subtl ...
Signal Discovery, Limits, and Uncertainties with Sparse On/Off Measurements: An Objective Bayesian Analysis

Knoetig, Max L.

For decades researchers have studied the On/Off counting problem where a measured rate consists of two parts. One part is due to a signal process and the other is due to a background process, the magnitudes for both of which are unknown. While most ...
Tests of in situ Formation Scenarios for Compact Multiplanet Systems

Schlaufman, Kevin C.

Kepler has identified over 600 multiplanet systems, many of which have several planets with orbital distances smaller than that of Mercury. Because these systems may be difficult to explain in the paradigm of core accretion and disk migration, it ha ...
Interpolation of PSF based on compressive sampling and its application in weak lensing survey

Suksmono, Andriyan B.

We propose a new point spread function (PSF) interpolation method based on compressive sampling (CS). Complex-Valued fractional Brownion motion (CV-fBm) field is used as a model of the PSF spatial distribution. The 1/f property of the fBm implies th ...
Visible near-diffraction-limited lucky imaging with full-sky laser-assisted adaptive optics

Basden, A. G.

Both lucky imaging techniques and adaptive optics require natural guide stars, limiting sky-coverage, even when laser guide stars are used. Lucky imaging techniques become less successful on larger telescopes unless adaptive optics is used, as the f ...
CorPITA: An Automated Algorithm for the Identification and Analysis of Coronal "EIT Waves"

Long, D. M.; Bloomfield, D. S.; Gallagher, P. T.; Pérez-Suárez, D.

The continuous stream of data available from the Atmospheric Imaging Assembly (AIA) telescopes onboard the Solar Dynamics Observatory (SDO) spacecraft has allowed a deeper understanding of the Sun. However, the sheer volume of data has necessitated ...
DAMEWARE: A Web Cyberinfrastructure for Astrophysical Data Mining

Brescia, Massimo; Cavuoti, Stefano; Longo, Giuseppe; Nocella, Alfonso; Garofalo, Mauro; Manna, Francesco; Esposito, Francesco; Albano, Giovanni; Guglielmo, Marisa; D'Angelo, Giovanni; Di Guido, Alessandro; George Djorgovski, S.; Donalek, Ciro; Mahabal, Ashish A.; Graham, Matthew J.; Fiore, Michelangelo; D'Abrusco, Raffaele

Astronomy is undergoing a methodological revolution triggered by an unprecedented wealth of complex and accurate data. The new panchromatic, synoptic sky surveys require advanced tools for discovering patterns and trends hidden behind data which are ...