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January - June 2014

Keplerian periodogram for Doppler exoplanet detection: optimized computation and analytic significance thresholds

Baluev, Roman V.

We consider the so-called Keplerian periodogram, in which the putative detectable signal is modelled by a highly non-linear Keplerian radial velocity function, appearing in Doppler exoplanetary surveys. We demonstrate that for planets on high-eccent ...
Generalized Fisher matrices

Heavens, A. F.; Seikel, M.; Nord, B. D.; Aich, M.; Bouffanais, Y.; Bassett, B. A.; Hobson, M. P.

The Fisher Information Matrix formalism (Fisher 1935) is extended to cases where the data are divided into two parts (X, Y), where the expectation value of Y depends on X according to some theoretical model, and X and Y both have errors with arbitra ...
Visualizing Astronomical Data with Blender

Kent, Brian R.

Astronomical data take on a multitude of forms - catalogs, data cubes, images, and simulations. The availability of software for rendering high-quality three-dimensional graphics lends itself to the paradigm of exploring the incredible parameter spa ...
DeBaCl: A Python Package for Interactive DEnsity-BAsed CLustering

Kent, Brian P.; Rinaldo, Alessandro; Verstynen, Timothy

The level set tree approach of Hartigan (1975) provides a probabilistically based and highly interpretable encoding of the clustering behavior of a dataset. By representing the hierarchy of data modes as a dendrogram of the level sets of a density e ...
On the estimation of intensity for low S/N ratio narrow emission lines

Rola, C.; Pelat, D.

The aim of this paper is to investigate the errors involved by the intensity measure of low signal-to-noise ratio narrow emission lines. We also studied the errors associated with line intensity ratios. The spectral data acquisition was simulated by ...
Sparse and Non-Negative BSS for Noisy Data

Jérémy Rapin, Jérôme Bobin, Anthony Larue, Jean-Luc Starck

Non-negative blind source separation (BSS) has raised interest in various fields of research, as testified by the wide literature on the topic of non-negative matrix factorization (NMF). In this context, it is fundamental that the sources to be esti ...
Joint Planck and WMAP CMB Map Reconstruction

J. Bobin, F. Sureau, J.-L. Starck, A. Rassat, P. Paykari

We present a novel estimate of the cosmological microwave background (CMB) map by combining the two latest full-sky microwave surveys: WMAP nine-year and Planck PR1. The joint processing benefits from a recently introduced component separation metho ...
GLIMPSE: Accurate 3D weak lensing reconstructions using sparsity

Adrienne Leonard, François Lanusse, Jean-Luc Starck

We present GLIMPSE - Gravitational Lensing Inversion and MaPping with Sparse Estimators - a new algorithm to generate density reconstructions in three dimensions from photometric weak lensing measurements. This is an extension of earlier work in one ...
Dark signal correction for a lukecold frame-transfer CCD. New method and application to the solar imager of the PICARD space mission

Hochedez, J.-F.; Timmermans, C.; Hauchecorne, A.; Meftah, M.

Context. Astrophysical observations must be corrected for their imperfections of instrumental origin. When charge-coupled devices (CCDs) are used, their dark signal is one such hindrance. In their pristine state, most CCD pixels are cool, that is, t ...
Flat-relative optimal extraction. A quick and efficient algorithm for stabilised spectrographs

Zechmeister, M.; Anglada-Escudé, G.; Reiners, A.

Context. Optimal extraction is a key step in processing the raw images of spectra as registered by two-dimensional detector arrays to a one-dimensional format. Previously reported algorithms reconstruct models for a mean one-dimensional spatial prof ...
Optimizing the search for transiting planets in long time series

Ofir, Aviv

Context. Transit surveys, both ground- and space-based, have already accumulated a large number of light curves that span several years. Aims: The search for transiting planets in these long time series is computationally intensive. We wish to opt ...
Optimized Principal Component Analysis on Coronagraphic Images of the Fomalhaut System

Meshkat, Tiffany; Kenworthy, Matthew A.; Quanz, Sascha P.; Amara, Adam

We present the results of a study to optimize the principal component analysis (PCA) algorithm for planet detection, a new algorithm complementing angular differential imaging and locally optimized combination of images (LOCI) for increasing the con ...
1SXPS: A Deep Swift X-Ray Telescope Point Source Catalog with Light Curves and Spectra

Evans, P. A.; Osborne, J. P.; Beardmore, A. P.; Page, K. L.; Willingale, R.; Mountford, C. J.; Pagani, C.; Burrows, D. N.; Kennea, J. A.; Perri, M.; Tagliaferri, G.; Gehrels, N.

We present the 1SXPS (Swift-XRT point source) catalog of 151,524 X-ray point sources detected by the Swift-XRT in 8 yr of operation. The catalog covers 1905 deg2 distributed approximately uniformly on the sky. We analyze the data in two ways. First ...
Photometric classification of emission line galaxies with machine-learning methods

Cavuoti, Stefano; Brescia, Massimo; D'Abrusco, Raffaele; Longo, Giuseppe; Paolillo, Maurizio

In this paper, we discuss an application of machine-learning-based methods to the identification of candidate active galactic nucleus (AGN) from optical survey data and to the automatic classification of AGNs in broad classes. We applied four differ ...
Bayes versus the virial theorem: inferring the potential of a galaxy from a kinematical snapshot

Magorrian, John

We present a new framework for estimating a galaxy's gravitational potential, Φ, from its stellar kinematics by adopting a fully non-parametric model for the galaxy's unknown action-space distribution function, f(J). Having an expression for the jo ...
Beyond stacking: a maximum-likelihood method to constrain radio source counts below the detection threshold

Mitchell-Wynne, Ketron; Santos, Mário G.; Afonso, José; Jarvis, Matt J.

We present a statistical method based on a maximum-likelihood approach to constrain the number counts of extragalactic sources below the nominal flux-density limit of continuum imaging surveys. We extract flux densities from a radio map using positi ...
Enabling non-parametric strong lensing models to derive reliable cluster mass distributions - WSLAP+

Sendra, Irene; Diego, Jose M.; Broadhurst, Tom; Lazkoz, Ruth

In the strong lensing regime, non-parametric models struggle to achieve sufficient angular resolution for a meaningful derivation of the central cluster mass distribution. Cluster members perturb lensed images and generate additional images, requiri ...
TEMPONEST: a Bayesian approach to pulsar timing analysis

Lentati, L.; Alexander, P.; Hobson, M. P.; Feroz, F.; van Haasteren, R.; Lee, K. J.; Shannon, R. M.

A new Bayesian software package for the analysis of pulsar timing data is presented in the form of TEMPONEST which allows for the robust determination of the non-linear pulsar timing solution simultaneously with a range of additional stochastic para ...
Bayesian lensing shear measurement

Bernstein, Gary M.; Armstrong, Robert

We derive an estimator of weak gravitational lensing shear from background galaxy images that avoids noise-induced biases through a rigorous Bayesian treatment of the measurement. The derived shear estimator disposes with the assignment of elliptici ...
Hierarchical reverberation mapping

Brewer, Brendon J.; Elliott, Tom M.

Reverberation mapping (RM) is an important technique in studies of active galactic nuclei (AGN). The key idea of RM is to measure the time lag τ between variations in the continuum emission from the accretion disc and subsequent response of the bro ...