- Model Comparison for the Density Structure across Solar Coronal Waveguides
- Arregui, I.; Soler, R.; Asensio Ramos, A.
The spatial variation of physical quantities, such as the mass density, across solar atmospheric waveguides governs the timescales and spatial scales for wave damping and energy dissipation. The direct measurement of the spatial distribution of dens …
- The Energy Dependence of GRB Minimum Variability Timescales
- Golkhou, V. Zach; Butler, Nathaniel R.; Littlejohns, Owen M.
We constrain the minimum variability timescales for 938 gamma-ray bursts (GRBs) observed by the Fermi/Gamma-ray Burst Monitor instrument prior to 2012 July 11. The tightest constraints on progenitor radii derived from these timescales are obtained f …
- Constrained correlation functions from the Millennium Simulation
- Wilking, P.; Röseler, R.; Schneider, P.
Context. In previous work, we developed a quasi-Gaussian approximation for the likelihood of correlation functions that incorporates fundamental mathematical constraints on correlation functions, in contrast to the usual Gaussian approach. The analy …
- The detection of Fermi AGN above 100 GeV using clustering analysis
- Armstrong, Thomas; Brown, Anthony M.; Chadwick, Paula M.; Nolan, S. J.
The density-based clustering algorithm DBSCAN has been applied to the Fermi Large Area Telescope (LAT) data set of Eγ ≥ 100 GeV events with |b| > 10°, in order to search for new very high energy (VHE) γ-ray sources. The clustering analysis retu …
- Three-dimensional extinction mapping and selection effects
- Sale, S. E.
Selection effects can bedevil the inference of the properties of a population of astronomical catalogues, unavoidably biasing the observed catalogue. This is particularly true when mapping interstellar extinction in three dimensions: more extinguish …
- Estimating stellar atmospheric parameters based on LASSO and support-vector regression
- Lu, Yu; Li, Xiangru
A scheme for estimating atmospheric parameters Teff, log g and [Fe/H] is proposed on the basis of the Least Absolute Shrinkage and Selection Operator (LASSO) algorithm and Haar wavelet. The proposed scheme consists of three processes. A spectrum is …
- Multifractal and Monofractal Scaling in a Laboratory MHD Turbulence Experiment
- Schaffner, D. A.; Brown, M. R.
Both multifractal and monofractal scaling of structure function exponents are observed in the turbulent magnetic fluctuations of the Swarthmore Spheromak Experiment plasma. Structure function and probability distribution function (PDF) analysis exhi …
- The Synthetic-Oversampling Method: Using Photometric Colors to Discover Extremely Metal-poor Stars
- Miller, A. A.
Extremely metal-poor (EMP) stars ([Fe/H] ≤ -3.0 dex) provide a unique window into understanding the first generation of stars and early chemical enrichment of the universe. EMP stars are exceptionally rare, however, and the relatively small number …
- Statistics of Measuring Neutron Star Radii: Assessing a Frequentist and a Bayesian Approach
- Özel, Feryal; Psaltis, Dimitrios
Measuring neutron star radii with spectroscopic and timing techniques relies on the combination of multiple observables to break the degeneracies between the mass and radius introduced by general relativistic effects. Here, we explore a previously u …
- Dissecting Magnetar Variability with Bayesian Hierarchical Models
- Huppenkothen, Daniela; Brewer, Brendon J.; Hogg, David W.; Murray, Iain; Frean, Marcus; Elenbaas, Chris; Watts, Anna L.; Levin, Yuri; van der Horst, Alexander J.; Kouveliotou, Chryssa
Neutron stars are a prime laboratory for testing physical processes under conditions of strong gravity, high density, and extreme magnetic fields. Among the zoo of neutron star phenomena, magnetars stand out for their bursting behavior, ranging from …
- Statistics of X-Ray Flares of Sagittarius A*: Evidence for Solar-like Self-organized Criticality Phenomena
- Li, Ya-Ping; Yuan, Feng; Yuan, Qiang; Wang, Q. Daniel; Chen, P. F.; Neilsen, Joseph; Fang, Taotao; Zhang, Shuo; Dexter, Jason
X-ray flares have routinely been observed from the supermassive black hole at our Galactic center, Sagittarius A{}\star (Sgr A⋆). The nature of these flares remains largely unclear, despite many theoretical models. In this paper, we study the stat …
- On the limit between short and long GRBs
- Tarnopolski, M.
Two classes of GRBs have been identified thus far without doubt and are prescribed to different physical scenarios—NS-NS or NS-BH mergers, and collapse of massive stars, for short and long GRBs, respectively. The existence of two distinct populati …
- Automated Transient Identification in the Dark Energy Survey
- Goldstein, D. A.; D’Andrea, C. B.; Fischer, J. A.; Foley, R. J.; Gupta, R. R.; Kessler, R.; Kim, A. G.; Nichol, R. C.; Nugent, P. E.; Papadopoulos, A.; Sako, M.; Smith, M.; Sullivan, M.; Thomas, R. C.; Wester, W.; Wolf, R. C.; Abdalla, F. B.; Banerji, M.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Carnero Rosell, A.; Castander, F. J.; da Costa, L. N.; Covarrubias, R.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Doel, P.; Eifler, T. F.; Fausti Neto, A.; Finley, D. A.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gerdes, D.; Gruen, D.; Gruendl, R. A.; James, D.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Maia, M. A. G.; Makler, M.; March, M.; Marshall, J. L.; Martini, P.; Merritt, K. W.; Miquel, R.; Nord, B.; Ogando, R.; Plazas, A. A.; Romer, A. K.; Roodman, A.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Walker, A. R.
We describe an algorithm for identifying point-source transients and moving objects on reference-subtracted optical images containing artifacts of processing and instrumentation. The algorithm makes use of the supervised machine learning technique k …
- Montblanc1: GPU accelerated radio interferometer measurement equations in support of Bayesian inference for radio observations
- Perkins, S. J.; Marais, P. C.; Zwart, J. T. L.; Natarajan, I.; Tasse, C.; Smirnov, O.
We present Montblanc, a GPU implementation of the Radio interferometer measurement equation (RIME) in support of the Bayesian inference for radio observations (BIRO) technique. BIRO uses Bayesian inference to select sky models that best match the vi …
- Nearest neighbor density ratio estimation for large-scale applications in astronomy
- Kremer, J.; Gieseke, F.; Steenstrup Pedersen, K.; Igel, C.
In astronomical applications of machine learning, the distribution of objects used for building a model is often different from the distribution of the objects the model is later applied to. This is known as sample selection bias, which is a major c …
- CosmoSIS: Modular cosmological parameter estimation
- Zuntz, J.; Paterno, M.; Jennings, E.; Rudd, D.; Manzotti, A.; Dodelson, S.; Bridle, S.; Sehrish, S.; Kowalkowski, J.
Cosmological parameter estimation is entering a new era. Large collaborations need to coordinate high-stakes analyses using multiple methods; furthermore such analyses have grown in complexity due to sophisticated models of cosmology and systematic …
- Analysis of Fermi gamma-ray burst duration distribution
- Tarnopolski, M.
Context. Two classes of gamma-ray bursts (GRBs), short and long, have been determined without any doubts, and are usually prescribed to different physical scenarios. A third class, intermediate in T90 durations has been reported in the datasets of B …
- Capabilities of future intensity interferometers for observing fast-rotating stars: imaging with two- and three-telescope correlations
- Nuñez, Paul D.; Domiciano de Souza, A.
Future large arrays of telescopes, used as intensity interferometers, can be used to image the surfaces of stars with unprecedented angular resolution. Fast-rotating, hot stars are particularly attractive targets for intensity interferometry since s …
- Improved shift estimates on extended Shack-Hartmann wavefront sensor images
- Townson, M. J.; Kellerer, A.; Saunter, C. D.
An important factor which affects performance of solar adaptive optics (AO) systems is the accuracy of tracking an extended object in the wavefront sensor. The accuracy of a centre-of-mass approach to image shift measurement depends on the parameter …
- Filament identification through mathematical morphology
- Koch, Eric W.; Rosolowsky, Erik W.
We present a new algorithm for detecting filamentary structure FILFINDER. The algorithm uses the techniques of mathematical morphology for filament identification, presenting a complementary approach to current algorithms which use matched filtering …