July – December 2015

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PYTRANSIT: fast and easy exoplanet transit modelling in PYTHON
Parviainen, Hannu

We present a fast and user friendly exoplanet transit light-curve modelling package PYTRANSIT, implementing optimized versions of the Giménez and Mandel & Agol transit models. The package offers an object-oriented PYTHON interface to access the two …

Astronomical Data Triage for Rapid Science Return
Brian D. Bue, Kiri L. Wagstaff, Umaa D. Rebbapragada, David R. Thompson, and Benyang Tang

The quantity of astronomical observations collected by today’s in- struments far exceeds the capability of manual inspection by domain experts. Rather than relying on human eyes to examine and analyze all collected data, we employ data triage algo …

The denoised, deconvolved, and decomposed Fermi γ-ray sky. An application of the D3PO algorithm
Selig, Marco; Vacca, Valentina; Oppermann, Niels; Enßlin, Torsten A.

We analyze the 6.5 year all-sky data from the Fermi Large Area Telescope that are restricted to γ-ray photons with energies between 0.6-307.2 GeV. Raw count maps show a superposition of diffuse and point-like emission structures and are subject to …

The denoised, deconvolved, and decomposed Fermi γ-ray sky. An application of the D3PO algorithm
Selig, Marco; Vacca, Valentina; Oppermann, Niels; Enßlin, Torsten A.

We analyze the 6.5 year all-sky data from the Fermi Large Area Telescope that are restricted to γ-ray photons with energies between 0.6-307.2 GeV. Raw count maps show a superposition of diffuse and point-like emission structures and are subject to …

A new approach to multifrequency synthesis in radio interferometry
Junklewitz, H.; Bell, M. R.; Enßlin, T.

We present a new approach to multifrequency synthesis in radio astronomy. Using Bayesian inference techniques, the new technique estimates the sky brightness and the spectral index simultaneously. In principle, the bandwidth of a wide-band observati …

A fast, always positive definite and normalizable approximation of non-Gaussian likelihoods
Sellentin, Elena

In this paper we extend the previously published DALI-approximation for likelihoods to cases in which the parameter dependence is in the covariance matrix. The approximation recovers non-Gaussian likelihoods, and reduces to the Fisher matrix approac …

SLUG – stochastically lighting up galaxies – III. A suite of tools for simulated photometry, spectroscopy, and Bayesian inference with stochastic stellar populations
Krumholz, Mark R.; Fumagalli, Michele; da Silva, Robert L.; Rendahl, Theodore; Parra, Jonathan

Stellar population synthesis techniques for predicting the observable light emitted by a stellar population have extensive applications in numerous areas of astronomy. However, accurate predictions for small populations of young stars, such as those …

On the angular distribution of IceCube high-energy events
de la Fuente Marcos, R.; de la Fuente Marcos, C.

The detection of high-energy astrophysical neutrinos of extraterrestrial origin by the IceCube neutrino observatory in Antarctica has opened a unique window to the cosmos that may help to probe both the distant Universe and our cosmic backyard. The …

Do the Kepler AGN light curves need reprocessing?
Kasliwal, Vishal P.; Vogeley, Michael S.; Richards, Gordon T.; Williams, Joshua; Carini, Michael T.

We gauge the impact of spacecraft-induced effects on the inferred variability properties of the light curve of the Seyfert 1 AGN Zw 229-15 observed by Kepler. We compare the light curve of Zw 229-15 obtained from the Kepler MAST data base with a rep …

A new map-making algorithm for CMB polarization experiments
Wallis, Christopher G. R.; Bonaldi, A.; Brown, Michael L.; Battye, Richard A.

With the temperature power spectrum of the cosmic microwave background (CMB) at least four orders of magnitude larger than the B-mode polarization power spectrum, any instrumental imperfections that couple temperature to polarization must be careful …

The overlooked potential of generalized linear models in astronomy – III. Bayesian negative binomial regression and globular cluster populations
de Souza, R. S.; Hilbe, J. M.; Buelens, B.; Riggs, J. D.; Cameron, E.; Ishida, E. E. O.; Chies-Santos, A. L.; Killedar, M.

In this paper, the third in a series illustrating the power of generalized linear models (GLMs) for the astronomical community, we elucidate the potential of the class of GLMs which handles count data. The size of a galaxy’s globular cluster (GC) po …

The analysis of indexed astronomical time series – XII. The statistics of oversampled Fourier spectra of noise plus a single sinusoid
Koen, Chris

With few exceptions, theoretical studies of periodogram properties focus on pure noise time series. This paper considers the case in which the time series consists of noise together with a single sinusoid, observed at regularly spaced time points. T …

Far beyond stacking: fully Bayesian constraints on sub-μJy radio source populations over the XMM-LSS-VIDEO field
Zwart, Jonathan T. L.; Santos, Mario; Jarvis, Matt J.

Measuring radio source counts is critical for characterizing new extragalactic populations, brings a wealth of science within reach and will inform forecasts for SKA and its pathfinders. Yet there is currently great debate (and few measurements) abo …

Scintillation noise in widefield radio interferometry
Vedantham, H. K.; Koopmans, L. V. E.

In this paper, we consider random phase fluctuations imposed during wave propagation through a turbulent plasma (e.g. ionosphere) as a source of additional noise in interferometric visibilities. We derive expressions for visibility variance for the …

The anisotropic line correlation function as a probe of anisotropies in galaxy surveys
Eggemeier, A.; Battefeld, T.; Smith, R. E.; Niemeyer, J.

We propose an anisotropic generalization of the line correlation function (ALCF) to separate and quantify phase information in the large-scale structure of galaxies. The line correlation function probes the strictly non-linear regime of structure fo …

A hybrid ensemble learning approach to star-galaxy classification
Kim, Edward J.; Brunner, Robert J.; Carrasco Kind, Matias

There exist a variety of star-galaxy classification techniques, each with their own strengths and weaknesses. In this paper, we present a novel meta-classification framework that combines and fully exploits different techniques to produce a more rob …

On the information content of the matter power spectrum
Carron, J.; Wolk, M.; Szapudi, I.

We discuss an analytical approximation for the matter power spectrum covariance matrix and its inverse on translinear scales, k ˜ 0.1h – 0.8 h Mpc-1 at z = 0. We proceed to give an analytical expression for the Fisher information matrix of the non- …

Constructing a Flexible Likelihood Function for Spectroscopic Inference
Czekala, Ian; Andrews, Sean M.; Mandel, Kaisey S.; Hogg, David W.; Green, Gregory M.

We present a modular, extensible likelihood framework for spectroscopic inference based on synthetic model spectra. The subtraction of an imperfect model from a continuously sampled spectrum introduces covariance between adjacent datapoints (pixels) …

Prediction of Solar Flare Size and Time-to-Flare Using Support Vector Machine Regression
Boucheron, Laura E.; Al-Ghraibah, Amani; McAteer, R. T. James

We study the prediction of solar flare size and time-to-flare using 38 features describing magnetic complexity of the photospheric magnetic field. This work uses support vector regression to formulate a mapping from the 38-dimensional feature space …

Periodograms for Multiband Astronomical Time Series
VanderPlas, Jacob T.; Ivezic, Željko

This paper introduces the multiband periodogram, a general extension of the well-known Lomb-Scargle approach for detecting periodic signals in time-domain data. In addition to advantages of the Lomb-Scargle method such as treatment of non-uniform sa …