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July - December 2012

Recalculation of data for short-lived radionuclide systems using less-biased ratio estimation

Telus, M.; Huss, G. R.; Ogliore, R. C.; Nagashima, K.; Tachibana, S.

Ratios determined from counting a subset of atoms in a sample are positively biased relative to the true ratio in the sample (Ogliore et al. 2011). The relative magnitude of the bias is approximately equal to the inverse of the counts in the denomin ...
The Mass-loss Return from Evolved Stars to the Large Magellanic Cloud. VI. Luminosities and Mass-loss Rates on Population Scales

Riebel, D.; Srinivasan, S.; Sargent, B.; Meixner, M.

We present results from the first application of the Grid of Red Supergiant and Asymptotic Giant Branch ModelS (GRAMS) model grid to the entire evolved stellar population of the Large Magellanic Cloud (LMC). GRAMS is a pre-computed grid of 80,843 ra ...
Early-type Galaxies at z = 1.3. I. The Lynx Supercluster: Cluster and Groups at z = 1.3. Morphology and Color-Magnitude Relation

Mei, Simona; Stanford, S. Adam; Holden, Brad P.; Raichoor, Anand; Postman, Marc; Nakata, Fumiaki; Finoguenov, Alexis; Ford, Holland C.; Illingworth, Garth D.; Kodama, Tadayuki; Rosati, Piero; Tanaka, Masayuki; Huertas-Company, Marc; Rettura, Alessandro; Shankar, Francesco; Carrasco, Eleazar R.; Demarco, Ricardo; Eisenhardt, Peter; Jee, Myungkook J.; Koyama, Yusei; White, Richard L.

We confirm the detection of three groups in the Lynx supercluster, at z ≈ 1.3, through spectroscopic follow-up and X-ray imaging, and we give estimates for their redshifts and masses. We study the properties of the group galaxies compared to the t ...
The impact of red noise in radial velocity planet searches: only three planets orbiting GJ 581?

Baluev, Roman V.

We perform a detailed analysis of the latest HARPS and Keck radial velocity data for the planet-hosting red dwarf GJ 581, which attracted a lot of attention in recent time. We show that these data contain important correlated noise component (`red n ...
A simple and robust method for automated photometric classification of supernovae using neural networks

Karpenka, N. V.; Feroz, F.; Hobson, M. P.

A method is presented for automated photometric classification of supernovae (SNe) as Type Ia or non-Ia. A two-step approach is adopted in which (i) the SN light curve flux measurements in each observing filter are fitted separately to an analytical ...
Measurement and calibration of noise bias in weak lensing galaxy shape estimation

Kacprzak, Tomasz; Zuntz, Joe; Rowe, Barnaby; Bridle, Sarah; Refregier, Alexandre; Amara, Adam; Voigt, Lisa; Hirsch, Michael

Weak gravitational lensing has the potential to constrain cosmological parameters to high precision. However, as shown by the Shear Testing Programmes and Gravitational lensing Accuracy Testing challenges, measuring galaxy shears is a non-trivial ta ...
A new method to detect solar-like oscillations at very low S/N using statistical significance testing

Lund, Mikkel N.; Chaplin, William J.; Kjeldsen, Hans

We introduce a new method to detect solar-like oscillations in frequency power spectra of stellar observations, under conditions of very low signal-to-noise ratio. The Moving-Windowed-Power-Search (MWPS) searches the power spectrum for signatures of ...
Construction of a Calibrated Probabilistic Classification Catalog: Application to 50k Variable Sources in the All-Sky Automated Survey

Richards, Joseph W.; Starr, Dan L.; Miller, Adam A.; Bloom, Joshua S.; Butler, Nathaniel R.; Brink, Henrik; Crellin-Quick, Arien

With growing data volumes from synoptic surveys, astronomers necessarily must become more abstracted from the discovery and introspection processes. Given the scarcity of follow-up resources, there is a particularly sharp onus on the frameworks that ...
Two-component Structure of the Hβ Broad-line Region in Quasars. I. Evidence from Spectral Principal Component Analysis

Hu, Chen; Wang, Jian-Min; Ho, Luis C.; Ferland, Gary J.; Baldwin, Jack A.; Wang, Ye

We report on a spectral principal component analysis (SPCA) of a sample of 816 quasars, selected to have small Fe II velocity shifts with spectral coverage in the rest wavelength range 3500-5500 Å. The sample is explicitly designed to mitigate spur ...
Spectral Classification of Galaxies at 0.5 <= z <= 1 in the CDFS: The Artificial Neural Network Approach

Teimoorinia, H.

The aim of this work is to combine spectral energy distribution (SED) fitting with artificial neural network techniques to assign spectral characteristics to a sample of galaxies at 0.5 < z < 1. The sample is selected from the spectroscopic campaign ...
Transit algorithm performance using real WASP data

Enoch, B.; Haswell, C. A.; Norton, A. J.; Collier-Cameron, A.; West, R. G.; Smith, A. M. S.; Parley, N. R.

Context. Many transiting exoplanet surveys are now in operation, observing millions of stars and searching for the periodic signals that may indicate planets orbiting these objects. Aims: We have tested the performance of transit detection algorit ...
The expected performance of stellar parametrization with Gaia spectrophotometry

Liu, C.; Bailer-Jones, C. A. L.; Sordo, R.; Vallenari, A.; Borrachero, R.; Luri, X.; Sartoretti, P.

Gaia will obtain astrometry and spectrophotometry for essentially all sources in the sky down to a broad-band magnitude limit of G = 20, an expected yield of 109 stars. Its main scientific objective is to reveal the formation and evolution of our Ga ...
A Bayesian algorithm for model selection applied to caustic-crossing binary-lens microlensing events

Kains, N.; Browne, P.; Horne, K.; Hundertmark, M.; Cassan, A.

We present a full Bayesian algorithm designed to perform automated searches of the parameter space of caustic-crossing binary-lens microlensing events. This builds on previous work implementing priors derived from Galactic models and geometrical con ...
Parameter-free Automatic Solar Active Region Detection by Hermite Function Decomposition

Harker, Brian J.

We present a new method for the automated detection of sunspots and active regions (ARs) from full-disk observations of the photospheric Stokes vector. The algorithm relies on a Hermite function decomposition of observed Stokes polarization profiles ...
Star-Galaxy Classification in Multi-band Optical Imaging

Fadely, Ross; Hogg, David W.; Willman, Beth

Ground-based optical surveys such as PanSTARRS, DES, and LSST will produce large catalogs to limiting magnitudes of r >~ 24. Star-galaxy separation poses a major challenge to such surveys because galaxies—even very compact galaxies—outnumber hal ...
Bayesian Confidence Limits of Electron Spectra Obtained Through Regularized Inversion of Solar Hard X-Ray Spectra

Emslie, A. Gordon; Massone, Anna Maria

Many astrophysical observations are characterized by a single, non-repeatable measurement of a source brightness or intensity, from which we are to construct estimates for the true intensity and its uncertainty. For example, the hard X-ray count spe ...
Distribution of Maximal Luminosity of Galaxies in the Sloan Digital Sky Survey

Taghizadeh-Popp, M.; Ozogány, K.; Rácz, Z.; Regoes, E.; Szalay, A. S.

Extreme value statistics is applied to the distribution of galaxy luminosities in the Sloan Digital Sky Survey. We analyze the DR8 Main Galaxy Sample (MGS), as well as the luminous red galaxies (LRGs). Maximal luminosities are sampled from batches c ...
Signal detection for spectroscopy and polarimetry

Asensio Ramos, A.; Manso Sainz, R.

The analysis of high spectral resolution spectroscopic and spectropolarimetric observations constitutes a very powerful way of inferring the dynamical, thermodynamical, and magnetic properties of distant objects. However, these techniques starve pho ...
A stacking method to study the gamma-ray emission of source samples based on the co-adding of Fermi-LAT count maps

Huber, B.; Farnier, C.; Manalaysay, A.; Straumann, U.; Walter, R.

Aims: We present a stacking method that makes use of co-added maps of gamma-ray counts produced from data taken with the Fermi Large Area Telescope. Sources with low integrated gamma-ray fluxes that are not detected individually may become detectabl ...
Non-Gaussianity and Minkowski functionals: forecasts for Planck

Ducout, A.; Bouchet, F. R.; Colombi, S.; Pogosyan, D.; Prunet, S.

We study Minkowski functionals as probes of primordial non-Gaussianity in the cosmic microwave background, specifically for the estimate of the primordial `local' bi-spectrum parameter f_{_NL}, with instrumental parameters which should be appropriat ...