January – June 2015

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Weighted principal component analysis: a weighted covariance eigendecomposition approach
Delchambre, L.

We present a new straightforward principal component analysis (PCA) method based on the diagonalization of the weighted variance-covariance matrix through two spectral decomposition methods: power iteration and Rayleigh quotient iteration. This meth …

Stacking of large interferometric data sets in the image- and uv-domain – a comparative study
Lindroos, L.; Knudsen, K. K.; Vlemmings, W.; Conway, J.; Martí-Vidal, I.

We present a new algorithm for stacking radio interferometric data in the uv-domain. The performance of uv-stacking is compared to the stacking of fully imaged data using simulated Atacama Large Millimeter/submillimeter Array and the Karl G. Jansky …

Photometric redshift estimation based on data mining with PhotoRApToR
Cavuoti, S.; Brescia, M.; De Stefano, V.; Longo, G.

Photometric redshifts (photo-z) are crucial to the scientific exploitation of modern panchromatic digital surveys. In this paper we present PhotoRApToR (Photometric Research Application To Redshift): a Java/C ++ based desktop application capable to …

Strong Lens Time Delay Challenge. II. Results of TDC1
Liao, Kai; Treu, Tommaso; Marshall, Phil; Fassnacht, Christopher D.; Rumbaugh, Nick; Dobler, Gregory; Aghamousa, Amir; Bonvin, Vivien; Courbin, Frederic; Hojjati, Alireza; Jackson, Neal; Kashyap, Vinay; Rathna Kumar, S.; Linder, Eric; Mandel, Kaisey; Meng, Xiao-Li; Meylan, Georges; Moustakas, Leonidas A.; Prabhu, Tushar P.; Romero-Wolf, Andrew; Shafieloo, Arman; Siemiginowska, Aneta; Stalin, Chelliah S.; Tak, Hyungsuk; Tewes, Malte; van Dyk, David

We present the results of the first strong lens time delay challenge. The motivation, experimental design, and entry level challenge are described in a companion paper. This paper presents the main challenge, TDC1, which consisted of analyzing thous …

Strong Lens Time Delay Challenge. I. Experimental Design
Dobler, Gregory; Fassnacht, Christopher D.; Treu, Tommaso; Marshall, Phil; Liao, Kai; Hojjati, Alireza; Linder, Eric; Rumbaugh, Nicholas

The time delays between point-like images in gravitational lens systems can be used to measure cosmological parameters. The number of lenses with measured time delays is growing rapidly; the upcoming Large Synoptic Survey Telescope (LSST) will monit …

Log-transforming the matter power spectrum
Greiner, M.; Ensslin, T. A.

We investigate whether non-linear effects on the large-scale power spectrum of dark matter, namely the increase in small-scale power and the smearing of baryon acoustic oscillations, can be decreased by a log-transformation or emulated by an exponen …

Photometric brown-dwarf classification. I. A method to identify and accurately classify large samples of brown dwarfs without spectroscopy
Skrzypek, N.; Warren, S. J.; Faherty, J. K.; Mortlock, D. J.; Burgasser, A. J.; Hewett, P. C.

Aims: We present a method, named photo-type, to identify and accurately classify L and T dwarfs onto the standard spectral classification system using photometry alone. This enables the creation of large and deep homogeneous samples of these objects …

Wavelet-based decomposition and analysis of structural patterns in astronomical images
Mertens, Florent; Lobanov, Andrei

Context. Images of spatially resolved astrophysical objects contain a wealth of morphological and dynamical information, and effectively extracting this information is of paramount importance for understanding the physics and evolution of these obje …

Applications of the Gaussian kinematic formula to CMB data analysis
Fantaye, Yabebal; Marinucci, Domenico; Hansen, Frode; Maino, Davide

The Gaussian kinematic formula (GKF) [R. J. Adler and J. E. Taylor, Random Fields and Geometry (Springer, New York, 2007).] is an extremely powerful tool allowing for explicit analytic predictions of expected values of Minkowski functionals under re …

A High-contrast Imaging Algorithm: Optimized Image Rotation and Subtraction
Dou, Jiangpei; Ren, Deqing; Zhao, Gang; Zhang, Xi; Chen, Rui; Zhu, Yongtian

Image Rotation and Subtraction (IRS) is a high-contrast imaging technique that can be used to suppress the speckle noise and facilitate the direct detection of exoplanets. IRS is different from Angular Differential Imaging (ADI), in that it will sub …

LOFAR sparse image reconstruction
Garsden, H.; Girard, J. N.; Starck, J. L.; Corbel, S.; Tasse, C.; Woiselle, A.; McKean, J. P.; van Amesfoort, A. S.; Anderson, J.; Avruch, I. M.; Beck, R.; Bentum, M. J.; Best, P.; Breitling, F.; Broderick, J.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; de Gasperin, F.; de Geus, E.; de Vos, M.; Duscha, S.; Eislöffel, J.; Engels, D.; Falcke, H.; Fallows, R. A.; Fender, R.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J.; Gunst, A. W.; Hassall, T. E.; Heald, G.; Hoeft, M.; Hörandel, J.; van der Horst, A.; Juette, E.; Karastergiou, A.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; Mann, G.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; Mulcahy, D. D.; Munk, H.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pandey, V. N.; Pietka, G.; Pizzo, R.; Polatidis, A. G.; Renting, A.; Röttgering, H.; Rowlinson, A.; Schwarz, D.; Sluman, J.; Smirnov, O.; Stappers, B. W.; Steinmetz, M.; Stewart, A.; Swinbank, J.; Tagger, M.; Tang, Y.; Tasse, C.; Thoudam, S.; Toribio, C.; Vermeulen, R.; Vocks, C.; van Weeren, R. J.; Wijnholds, S. J.; Wise, M. W.; Wucknitz, O.; Yatawatta, S.; Zarka, P.; Zensus, A.

Context. The LOw Frequency ARray (LOFAR) radio telescope is a giant digital phased array interferometer with multiple antennas distributed in Europe. It provides discrete sets of Fourier components of the sky brightness. Recovering the original brig …

Super-resolution method using sparse regularization for point-spread function recovery
Ngolè Mboula, F. M.; Starck, J.-L.; Ronayette, S.; Okumura, K.; Amiaux, J.

In large-scale spatial surveys, such as the forthcoming ESA Euclid mission, images may be undersampled due to the optical sensors sizes. Therefore, one may consider using a super-resolution (SR) method to recover aliased frequencies, prior to furthe …

Sequential Covariance Calculation for Exoplanet Image Processing
Savransky, Dmitry

Direct imaging of exoplanets involves the extraction of very faint signals from highly noisy data sets, with noise that often exhibits significant spatial, spectral, and temporal correlations. As a result, a large number of post-processing algorithm …

A Framework for Statistical Inference in Astrophysics
Chad M. Schafer

The rapid growth of astronomical data sets, coupled with the complexity of the questions scientists seek to answer with these data, creates an increasing need for the utilization of advanced statistical inference methods in astro- physics. Here, foc …

Variable Selection for Modeling the Absolute Magnitude at Maximum of Type Ia Supernovae
Makoto Uemura, Koji, S. Kawabata, Shiro Ikeda, Keiichi Maeda

We discuss what is an appropriate set of explanatory variables in order to predict the absolute magnitude at the maximum of Type Ia supernovae. In order to have a good prediction, the error for future data, which is called the “generalization erro …

Classic papers in Bayesian statistics
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A list compiled by Julyan Arbel, Collegio Carlo Alberto, IT, with access to full text papers.

Counting and confusion: Bayesian rate estimation with multiple populations
Farr, Will M.; Gair, Jonathan R.; Mandel, Ilya; Cutler, Curt

We show how to obtain a Bayesian estimate of the rates or numbers of signal and background events from a set of events when the shapes of the signal and background distributions are known, can be estimated, or approximated; our method works well eve …

Parameter estimation for compact binaries with ground-based gravitational-wave observations using the LALInference software library
Veitch, J.; Raymond, V.; Farr, B.; Farr, W.; Graff, P.; Vitale, S.; Aylott, B.; Blackburn, K.; Christensen, N.; Coughlin, M.; Del Pozzo, W.; Feroz, F.; Gair, J.; Haster, C.-J.; Kalogera, V.; Littenberg, T.; Mandel, I.; O’Shaughnessy, R.; Pitkin, M.; Rodriguez, C.; Röver, C.; Sidery, T.; Smith, R.; Van Der Sluys, M.; Vecchio, A.; Vousden, W.; Wade, L.

The Advanced LIGO and Advanced Virgo gravitational-wave (GW) detectors will begin operation in the coming years, with compact binary coalescence events a likely source for the first detections. The gravitational waveforms emitted directly encode inf …

Model-independent forecasts of CMB angular power spectra for the Planck mission
Aghamousa, Amir; Arjunwadkar, Mihir; Souradeep, Tarun

The Planck mission, designed for making measurements of the cosmic microwave background (CMB) radiation with unprecedented accuracy and angular resolution, is expected to release its entire data in the near future. In this paper, we provide model-in …

Epoch of reionization window. II. Statistical methods for foreground wedge reduction
Liu, Adrian; Parsons, Aaron R.; Trott, Cathryn M.

For there to be a successful measurement of the 21 cm epoch of reionization (EoR) power spectrum, it is crucial that strong foreground contaminants be robustly suppressed. These foregrounds come from a variety of sources (such as Galactic synchrotro …