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January - June 2015

Obscuration-dependent Evolution of Active Galactic Nuclei

Buchner, Johannes; Georgakakis, Antonis; Nandra, Kirpal; Brightman, Murray; Menzel, Marie-Luise; Liu, Zhu; Hsu, Li-Ting; Salvato, Mara; Rangel, Cyprian; Aird, James; Merloni, Andrea; Ross, Nicholas

We aim to constrain the evolution of active galactic nuclei (AGNs) as a function of obscuration using an X-ray-selected sample of ~2000 AGNs from a multi-tiered survey including the CDFS, AEGIS-XD, COSMOS, and XMM-XXL fields. The spectra of individ ...
Accurate Estimators of Correlation Functions in Fourier Space

Sefusatti, E.; Crocce, M.; Scoccimarro, R.; Couchman, H. M. P.

Efficient estimators of Fourier-space statistics for large number of objects rely on Fast Fourier Transforms (FFTs), which are affected by aliasing from unresolved small scale modes due to the finite FFT grid. Aliasing takes the form of a sum over i ...
Interval Estimation for a Binomial Proportion

Lawrence D. Brown, T. Tony Cai and Anirban DasGupta

We revisit the problem of interval estimation of a binomial proportion. The erratic behavior of the coverage probability of the standard Wald confidence interval has previously been remarked on in the literature (Blyth and Still, Agresti and Coull, ...
Some Aspects of Measurement Error in Linear Regression of Astronomical Data

Kelly, Brandon C.

I describe a Bayesian method to account for measurement errors in linear regression of astronomical data. The method allows for heteroscedastic and possibly correlated measurement errors and intrinsic scatter in the regression relationship. The meth ...
10 Simple Rules for the Care and Feeding of Scientific Data

Alyssa Goodman, Alberto Pepe, Alexander W. Blocker, Christine L. Borgman, Kyle Cranmer, Mercè Crosas, Rosanne Di Stefano, Yolanda Gil, Paul Groth, Margaret Hedstrom, David W. Hogg, Vinay Kashyap, Ashish Mahabal, Aneta Siemiginowska, Aleksandra Slavkovic

This article offers a short guide to the steps scientists can take to ensure that their data and associated analyses continue to be of value and to be recognized. In just the past few years, hundreds of scholarly papers and reports have been written ...
The Energy-Dependence of GRB Minimum Variability Timescales

V. Zach Golkhou, Nathaniel R. Butler, Owen M. Littlejohns

We constrain the minimum variability timescales for 938 GRBs observed by the Fermi/GBM instrument prior to July 11, 2012. The tightest constraints on progenitor radii derived from these timescales are obtained from light curves in the hardest energy ...
Discovery of ˜9000 new RR Lyrae in the southern Catalina surveys

Torrealba, G.; Catelan, M.; Drake, A. J.; Djorgovski, S. G.; McNaught, R. H.; Belokurov, V.; Koposov, S.; Graham, M. J.; Mahabal, A.; Larson, S.; Christensen, E.

We present the results of a deep, wide-area variability survey in the Southern hemisphere, the first of its kind. As part of the Catalina Sky Surveys, the Siding Spring Survey (SSS) has covered 14 800 deg2 in the declination range of -75° ≤ δ � ...
Enhanced models for stellar Doppler noise reveal hints of a 13-year activity cycle of 55 Cancri

Baluev, Roman V.

We consider the impact of Doppler noise models on the statistical robustness of the exoplanetary radial velocity fits. We show that the traditional model of the Doppler noise with an additive jitter can generate large non-linearity effects, decreasi ...
A Machine-learning Method to Infer Fundamental Stellar Parameters from Photometric Light Curves

Miller, A. A.; Bloom, J. S.; Richards, J. W.; Lee, Y. S.; Starr, D. L.; Butler, N. R.; Tokarz, S.; Smith, N.; Eisner, J. A.

A fundamental challenge for wide-field imaging surveys is obtaining follow-up spectroscopic observations: there are >109 photometrically cataloged sources, yet modern spectroscopic surveys are limited to ~few× 106 targets. As we approach the Large ...
Simulated Performance of Timescale Metrics for Aperiodic Light Curves

Findeisen, Krzysztof; Cody, Ann Marie; Hillenbrand, Lynne

Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time-domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic vari ...
Coronal Fourier Power Spectra: Implications for Coronal Seismology and Coronal Heating

Ireland, J.; McAteer, R. T. J.; Inglis, A. R.

The dynamics of regions of the solar corona are investigated using Atmospheric Imaging Assembly 171 Å and 193 Å data. The coronal emission from the quiet Sun, coronal loop footprints, coronal moss, and from above a sunspot is studied. It is shown ...
BGLS: A Bayesian formalism for the generalised Lomb-Scargle periodogram

Mortier, A.; Faria, J. P.; Correia, C. M.; Santerne, A.; Santos, N. C.

Context. Frequency analyses are very important in astronomy today, not least in the ever-growing field of exoplanets, where short-period signals in stellar radial velocity data are investigated. Periodograms are the main (and powerful) tools for thi ...
A method to deconvolve mass ratio distribution of binary stars

Curé, Michel; Rial, Diego F.; Cassetti, Julia; Christen, Alejandra; Boffin, Henri M. J.

Aims: It is important to know the binary mass-ratio distribution to better understand the evolution of stars in binary systems and to constrain their formation. However, in most cases, that is, for single-lined spectroscopic binaries, the mass ratio ...
Hierarchical Bayesian analysis of the velocity power spectrum in supersonic turbulence

Konstandin, L.; Shetty, R.; Girichidis, P.; Klessen, R. S.

Turbulence is a dominant feature operating in gaseous flows across nearly all scales in astrophysical environments. Accordingly, accurately estimating the statistical properties of such flows is necessary for developing a comprehensive understanding ...
Science Parametrics for Missions to Search for Earth-like Exoplanets by Direct Imaging

Brown, Robert A.

We use Nt , the number of exoplanets observed in time t, as a science metric to study direct-search missions like Terrestrial Planet Finder. In our model, N has 27 parameters, divided into three categories: 2 astronomical, 7 instrumental, and 18 sci ...
Objective Bayesian Analysis of "on/off" Measurements

Casadei, Diego

In high-energy astrophysics, it is common practice to account for the background overlaid with counts from the source of interest with the help of auxiliary measurements carried out by pointing off-source. In this "on/off" measurement, one knows the ...
Gamma-ray burst engines may have no memory

Baldeschi, A.; Guidorzi, C.

Context. A sizeable fraction of gamma-ray burst (GRB) time profiles consist of a temporal sequence of pulses. The nature of this stochastic process carries information on how GRB inner engines work. The so-called interpulse time defines the interval ...
BAYES-X: a Bayesian inference tool for the analysis of X-ray observations of galaxy clusters

Olamaie, Malak; Feroz, Farhan; Grainge, Keith J. B.; Hobson, Michael P.; Sanders, Jeremy S.; Saunders, Richard D. E.

We present the first public release of our Bayesian inference tool, BAYES-X, for the analysis of X-ray observations of galaxy clusters. We illustrate the use of BAYES-X by analysing a set of four simulated clusters at z = 0.2-0.9 as they would be ob ...
The SAMI Galaxy Survey: cubism and covariance, putting round pegs into square holes

Sharp, R.; Allen, J. T.; Fogarty, L. M. R.; Croom, S. M.; Cortese, L.; Green, A. W.; Nielsen, J.; Richards, S. N.; Scott, N.; Taylor, E. N.; Barnes, L. A.; Bauer, A. E.; Birchall, M.; Bland-Hawthorn, J.; Bloom, J. V.; Brough, S.; Bryant, J. J.; Cecil, G. N.; Colless, M.; Couch, W. J.; Drinkwater, M. J.; Driver, S.; Foster, C.; Goodwin, M.; Gunawardhana, M. L. P.; Ho, I.-T.; Hampton, E. J.; Hopkins, A. M.; Jones, H.; Konstantopoulos, I. S.; Lawrence, J. S.; Leslie, S. K.; Lewis, G. F.; Liske, J.; López-Sánchez, Á. R.; Lorente, N. P. F.; McElroy, R.; Medling, A. M.; Mahajan, S.; Mould, J.; Parker, Q.; Pracy, M. B.; Obreschkow, D.; Owers, M. S.; Schaefer, A. L.; Sweet, S. M.; Thomas, A. D.; Tonini, C.; Walcher, C. J.

We present a methodology for the regularization and combination of sparse sampled and irregularly gridded observations from fibre-optic multiobject integral field spectroscopy. The approach minimizes interpolation and retains image resolution on com ...
Galaxy And Mass Assembly (GAMA): the halo mass of galaxy groups from maximum-likelihood weak lensing

Han, Jiaxin; Eke, Vincent R.; Frenk, Carlos S.; Mandelbaum, Rachel; Norberg, Peder; Schneider, Michael D.; Peacock, John A.; Jing, Yipeng; Baldry, Ivan; Bland-Hawthorn, Joss; Brough, Sarah; Brown, Michael J. I.; Liske, Jochen; Loveday, Jon; Robotham, Aaron S. G.

We present a maximum-likelihood weak-lensing analysis of the mass distribution in optically selected spectroscopic Galaxy Groups (G3Cv5) in the Galaxy And Mass Assembly (GAMA) survey, using background Sloan Digital Sky Survey (SDSS) photometric gala ...