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July-December 2011

Automated measurement of redshifts from mid-infrared low-resolution spectroscopy

Hernán Caballero, Antonio

Obtaining accurate redshifts from mid-infrared (MIR) low-resolution (R ˜ 100) spectroscopy is challenging because the wavelength resolution is too low to detect narrow lines in most cases. Yet, the number of degrees of freedom and diversity of spec ...
Spectral Classification and Redshift Measurement for the SDSS-III Baryon Oscillation Spectroscopic Survey

Bolton, Adam S.; Schlegel, David J.; Aubourg, Éric; Bailey, Stephen; Bhardwaj, Vaishali; Brownstein, Joel R.; Burles, Scott; Chen, Yan-Mei; Dawson, Kyle; Eisenstein, Daniel J.; Gunn, James E.; Knapp, G. R.; Loomis, Craig P.; Lupton, Robert H.; Maraston, Claudia; Muna, Demitri; Myers, Adam D.; Olmstead, Matthew D.; Padmanabhan, Nikhil; Pâris, Isabelle; Percival, Will J.; Petitjean, Patrick; Rockosi, Constance M.; Ross, Nicholas P.; Schneider, Donald P.; Shu, Yiping; Strauss, Michael A.; Thomas, Daniel; Tremonti, Christy A.; Wake, David A.; Weaver, Benjamin A.; Wood-Vasey, W. Michael

We describe the automated spectral classification, redshift determination, and parameter measurement pipeline in use for the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III (SDSS-III) as of the survey's ninth data ...
Combining Independent, Weighted P-Values: Achieving Computational Stability by a Systematic Expansion with Controllable Accuracy

Gelio Alves, Yi-Kuo Yu

Given the expanding availability of scientific data and tools to analyze them, combining different assessments of the same piece of information has become increasingly important for social, biological, and even physical sciences. This task demands, ...
Analyzing and Visualizing Cosmological Simulations with ParaView

Woodring, Jonathan; Heitmann, Katrin; Ahrens, James; Fasel, Patricia; Hsu, Chung-Hsing; Habib, Salman; Pope, Adrian

The advent of large cosmological sky surveys—ushering in the era of precision cosmology—has been accompanied by ever larger cosmological simulations. The analysis of these simulations, which currently encompass tens of billions of particles and ...
A photometric catalogue of quasars and other point sources in the Sloan Digital Sky Survey

Sheelu Abraham, Ninan Sajeeth Philip, Ajit Kembhavi, Yogesh G. Wadadekar and Rita Sinha

We present a catalogue of about six million unresolved photometric detections in the Sloan Digital Sky Survey (SDSS) Seventh Data Release, classifying them into stars, galaxies and quasars. We use a machine learning classifier trained on a subset ...
A Learning Algorithm based on Primary School Teaching Wisdom

Ninan Sajeeth Philip

A learning algorithm based on primary school teaching and learning is presented. The methodology is to continuously evaluate the performance of the network and to train it on the examples for which they repeatedly fail, until all the examples are co ...
A Student-t based filter for robust signal detection

Christian Röver

The search for gravitational-wave signals in detector data is often hampered by the fact that many data analysis methods are based on the theory of stationary Gaussian noise, while actual measurement data frequently exhibit clear departures from the ...
Bayesian versus frequentist upper limits

Christian Röver, Chris Messenger, Reinhard Prix

While gravitational waves have not yet been measured directly, data analysis from detection experiments commonly includes an upper limit statement. Such upper limits may be derived via a frequentist or Bayesian approach; the theoretical implications ...
Bayesian reconstruction of gravitational wave burst signals from simulations of rotating stellar core collapse and bounce

Christian Röver, Marie-Anne Bizouard, Nelson Christensen, Harald Dimmelmeier, Ik Siong Heng, Renate Meyer

Presented in this paper is a technique that we propose for extracting the physical parameters of a rotating stellar core collapse from the observation of the associated gravitational wave signal from the collapse and core bounce. Data from interfero ...
Coherent Bayesian inference on compact binary inspirals using a network of interferometric gravitational wave detectors

Christian Röver, Renate Meyer, Nelson Christensen

Presented in this paper is a Markov chain Monte Carlo (MCMC) routine for conducting coherent parameter estimation for interferometric gravitational wave observations of an inspiral of binary compact objects using data from multiple detectors. The MC ...
Information field theory for cosmological perturbation reconstruction and non-linear signal analysis

Torsten A. Ensslin, Mona Frommert, Francisco S. Kitaura

We develop information field theory (IFT) as a means of Bayesian inference on spatially distributed signals, the information fields. A didactical approach is attempted. Starting from general considerations on the nature of measurements, signals, ...
Inference with minimal Gibbs free energy in information field theory

Torsten A. Enßlin, Cornelius Weig

Non-linear and non-Gaussian signal inference problems are difficult to tackle. Renormalization techniques permit us to construct good estimators for the posterior signal mean within information field theory (IFT), but the approximations and assumpti ...
Reconstruction of signals with unknown spectra in information field theory with parameter uncertainty

Torsten Enßlin, Mona Frommert

The optimal reconstruction of cosmic metric perturbations and other signals requires knowledge of their power spectra and other parameters. If these are not known a priori, they have to be measured simultaneously from the same data used for the sign ...
Reconstructing signals from noisy data with unknown signal and noise covariance

Niels Oppermann, Georg Robbers, Torsten A. Enßlin

We derive a method to reconstruct Gaussian signals from linear measurements with Gaussian noise. This new algorithm is intended for applications in astrophysics and other sciences. The starting point of our considerations is the principle of minimum ...
An improved map of the Galactic Faraday sky

N. Oppermann, H. Junklewitz, G. Robbers, M. R. Bell, T. A. Enßlin, A. Bonafede, R. Braun, J. C. Brown, T. E. Clarke, I. J. Feain, B. M. Gaensler, A. Hammond, L. Harvey-Smith, G. Heald, M. Johston-Hollitt, U. Klein, P. P. Kronberg, S. A. Mao, N. M. McClure-Griffiths, S. P. O'Sullivan, L. Pratley, T. Robishaw, S. Roy, D. H. F. M. Schnitzeler, C. Sotomayor-Beltran, J. Stevens, J. M. Stil, C. Sunstrum, A. Tanna, A. R. Taylor, C. L. Van Eck

We aim to summarize the current state of knowledge regarding Galactic Faraday rotation in an all-sky map of the Galactic Faraday depth. For this we have assembled the most extensive catalog of Faraday rotation data of compact extragalactic polarized ...
Improving stochastic estimates with inference methods: calculating matrix diagonals

Marco Selig, Niels Oppermann, Torsten A. Enßlin

Estimating the diagonal entries of a matrix, that is not directly accessible but only available as a linear operator in the form of a computer routine, is a common necessity in many computational applications, especially in image reconstruction and ...
Bayesian analysis of spatially distorted cosmic signals from Poissonian data

Cornelius Weig, Torsten Ensslin

Reconstructing the matter density field from galaxy counts is a problem frequently addressed in current literature. Two main sources of error are shot noise from galaxy counts and insufficient knowledge of the correct galaxy position because of pecu ...
Bayesian non-linear large-scale structure inference of the Sloan Digital Sky Survey Data Release 7

J. Jasche, F. S. Kitaura, C. Li, T. A. Enßlin

In this work, we present the first non-linear, non-Gaussian full Bayesian large-scale structure analysis of the cosmic density field conducted so far. The density inference is based on the Sloan Digital Sky Survey (SDSS) Data Release 7, which covers ...
Bayesian power-spectrum inference for large-scale structure data

J. Jasche, F. S. Kitaura, B. D. Wandelt, T. A. Enßlin

We describe an exact, flexible and computationally efficient algorithm for a joint inference of the large-scale structure and its power spectrum, building on a Gibbs sampling framework and present its implementation ARES (Algorithm for REconstructio ...
Probing magnetic helicity with synchrotron radiation and Faraday rotation

N. Oppermann, H. Junklewitz, G. Robbers, T. A. Enßlin

We present a first application of the recently proposed LITMUS test for magnetic helicity, as well as a thorough study of its applicability under different circumstances. In order to apply this test to the galactic magnetic field, the newly develope ...