- Mining the VVV: star formation and embedded clusters
- Solin, O.; Haikala, L.; Ukkonen, E.
Aims: We aim to locate previously unknown stellar clusters using the VISTA variables in the Vía Láctea Survey (VVV) catalogue data. Methods: The method fits a mixture model of Gaussian densities and background noise and uses the expectation maxi …
- The hierarchical nature of the spin alignment of dark matter haloes in filaments
- Aragon-Calvo, M. A.; Yang, Lin Forrest
Dark matter haloes in cosmological filaments and walls have (in average) their spin vector aligned with their host structure. While haloes in walls are aligned with the plane of the wall independently of their mass, haloes in filaments present a mas …
- 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 …
- The busy function: a new analytic function for describing the integrated 21-cm spectral profile of galaxies
- Westmeier, T.; Jurek, R.; Obreschkow, D.; Koribalski, B. S.; Staveley-Smith, L.
Accurate parametrization of galaxies detected in the 21-cm H I emission is of fundamental importance to the measurement of commonly used indicators of galaxy evolution, including the Tully-Fisher relation and the H I mass function. Here, we propose …
- Weak lensing galaxy cluster field reconstruction
- Jullo, E.; Pires, S.; Jauzac, M.; Kneib, J.-P.
In this paper, we compare three methods to reconstruct galaxy cluster density fields with weak lensing data. The first method called FLens integrates an inpainting concept to invert the shear field with possible gaps, and a multi-scale entropy denoi …
- Pysca – Automated frequency extraction from photometric time series
- Herzberg, Wiebke; Glogowski, Kolja
Pysca, a Python software package for automated extraction of frequencies, amplitudes and phases from non-equally sampled photometric time series, is presented.
- On the necessity of a new interpretation of the stellar light curves
- Pascual-Granado, J.; Garrido, R.; Suárez, J. C.
The power of asteroseismology relies on the ability to infer the stellar structure from the unambiguous frequency identification of the corresponding pulsation mode. Hence, the use of a Fourier transform is in the basis of asteroseismic studies. Nev …
- Asteroseismology of Evolved Stars with Kepler: A New Way to Constrain Stellar Interiors Using Mode Inertias
- Benomar, O.; Belkacem, K.; Bedding, T. R.; Stello, D.; Di Mauro, M. P.; Ventura, R.; Mosser, B.; Goupil, M. J.; Samadi, R.; Garcia, R. A.
The asteroseismology of evolved solar-like stars is experiencing growing interest due to the wealth of observational data from space-borne instruments such as the CoRoT and Kepler spacecraft. In particular, the recent detection of mixed modes, which …
- Searching for Pulsars Using Image Pattern Recognition
- Zhu, W. W.; Berndsen, A.; Madsen, E. C.; Tan, M.; Stairs, I. H.; Brazier, A.; Lazarus, P.; Lynch, R.; Scholz, P.; Stovall, K.; Ransom, S. M.; Banaszak, S.; Biwer, C. M.; Cohen, S.; Dartez, L. P.; Flanigan, J.; Lunsford, G.; Martinez, J. G.; Mata, A.; Rohr, M.; Walker, A.; Allen, B.; Bhat, N. D. R.; Bogdanov, S.; Camilo, F.; Chatterjee, S.; Cordes, J. M.; Crawford, F.; Deneva, J. S.; Desvignes, G.; Ferdman, R. D.; Freire, P. C. C.; Hessels, J. W. T.; Jenet, F. A.; Kaplan, D. L.; Kaspi, V. M.; Knispel, B.; Lee, K. J.; van Leeuwen, J.; Lyne, A. G.; McLaughlin, M. A.; Siemens, X.; Spitler, L. G.; Venkataraman, A.
In the modern era of big data, many fields of astronomy are generating huge volumes of data, the analysis of which can sometimes be the limiting factor in research. Fortunately, computer scientists have developed powerful data-mining techniques that …
- All-sky Interferometry with Spherical Harmonic Transit Telescopes
- Shaw, J. Richard; Sigurdson, Kris; Pen, Ue-Li; Stebbins, Albert; Sitwell, Michael
In this paper, we describe the spherical harmonic transit telescope through the use of a novel formalism for the analysis of transit radio telescopes. This all-sky approach bypasses the curved-sky complications of traditional interferometry and so i …
- Magnetic activity of F stars observed by Kepler
- Mathur, S.; García, R. A.; Ballot, J.; Ceillier, T.; Salabert, D.; Metcalfe, T. S.; Régulo, C.; Jiménez, A.; Bloemen, S.
Context. The study of stellar activity is important because it can provide new constraints for dynamo models when combined with surface rotation rates and the depth of the convection zone. We know that the dynamo mechanism, which is believed to be t …
- Artificial neural network to search for metal-poor galaxies
- Shi, Fei; Liu, Yu-Yan; Kong, Xu; Chen, Yang
Aims: To find a fast and reliable method for selecting metal-poor galaxies (MPGs), especially in large surveys and huge databases, an artificial neural network (ANN) method is applied to a sample of star-forming galaxies from the Sloan Digital Sky S …
- Quick-MESS: A fast statistical tool for Exoplanet Imaging Surveys
- Bonavita, Mariangela; De Mooij, Ernst; Jayawardhana, Ray; Gratton, Raffaele
Several tools have been developed for the analysis of the results of direct imaging exoplanet surveys, mostly using a combination of Monte-Carlo simulations or a Bayesian approach. Here we present a novel approach to the statistical analysis of Dire …
- TLOCI: A Fully Loaded Speckle Killing Machine
- Marois, Christian; Correia, Carlos; Véran, Jean-Pierre; Currie, Thayne
A new high-contrast imaging subtraction algorithm (TLOCI) is presented to maximize a planet signal-to-noise ratio. The technique uses an input spectrum and template PSFs to optimize the reference image coefficient determination to minimize the flux …
- GRAPHIC: The Geneva Reduction and Analysis Pipeline for High-contrast Imaging of planetary Companions
- Hagelberg, Janis; Ségransan, Damien; Udry, Stéphane; Wildi, François
We present a new analysis and reduction pipeline for the detection of planetary companions using Angular Differential Imaging. The pipeline uses Fourier transforms for image shifting and rotation in order to achieve very low signal loss. Furthermore …
- Artificial neural network based calibrations for the prediction of galactic [N II] λ6584 and Hα line luminosities
- Teimoorinia, Hossein; Ellison, Sara L.
The artificial neural network (ANN) is a well-established mathematical technique for data prediction, based on the identification of correlations and pattern recognition in input training sets. We present the application of ANNs to predict the emiss …
- Weighing the Giants – III. Methods and measurements of accurate galaxy cluster weak-lensing masses
- Applegate, Douglas E.; von der Linden, Anja; Kelly, Patrick L.; Allen, Mark T.; Allen, Steven W.; Burchat, Patricia R.; Burke, David L.; Ebeling, Harald; Mantz, Adam; Morris, R. Glenn
We report weak-lensing masses for 51 of the most X-ray luminous galaxy clusters known. This cluster sample, introduced earlier in this series of papers, spans redshifts 0.15 ≲ zcl ≲ 0.7, and is well suited to calibrate mass proxies for current c …
- 3D Galactic dust extinction mapping with multiband photometry
- Hanson, R. J.; Bailer-Jones, C. A. L. We present a method to simultaneously infer the interstellar extinction parameters A0 and R0, stellar effective temperature Teff and distance modulus μ in a Bayesian framework. Using multiband photometry from Sloan Digital Sky Survey and UKIRT Infrared Deep Sky Survey, we train a forward model to emulate the colour change due to physical properties of stars and the interstellar medium for temperatures from 4000 to 9000 K and extinctions from 0 to 5 mag. We introduce a Hertzsprung-Russell diagram prior to account for physical constraints on the distribution of stars in the temperature-absolute magnitude plane. This allows us to infer distances probabilistically. Influences of colour information, priors and model parameters are explored. Residual mean absolute errors (MAEs) on a set of objects for extinction and temperature are 0.2 mag and 300 K, respectively, for R0 fixed to 3.1. For variable R0, we obtain MAEs of 0.37 mag, 412.9 K and 0.74 for A0, Teff and R0, respectively. Distance moduli are accurate to approximately 2 mag. Quantifying the precisions of individual parameter estimates with 68 per cent confidence interval of the posterior distribution, we obtain 0.05 mag, 66 K, 2 mag and 0.07 for A0, Teff, μ and R0, respectively, although we find that these underestimate the accuracy of the model. We produce two-dimensional maps in extinction and R0 that are compared to previous work. Furthermore, we incorporate the inferred distance information to compute fully probabilistic distance profiles for individual lines of sight. The individual stellar astrophysical parameter (AP) estimates, combined with inferred 3D information, will make possible many Galactic science and modelling applications. Adapting our method to work with other surveys, such as Pan-STARRS and Gaia, will allow us to probe other regions of the Galaxy.
We present a method to simultaneously infer the interstellar extinction parameters A0 and R0, stellar effective temperature Teff and distance modulus μ in a Bayesian framework. Using multiband photometry from Sloan Digital Sky Survey and UKIRT Infr …
- An analytic method to compute star cluster luminosity statistics
- da Silva, Robert L.; Krumholz, Mark R.; Fumagalli, Michele; Fall, S. Michael
The luminosity distribution of the brightest star clusters in a population of galaxies encodes critical pieces of information about how clusters form, evolve and disperse, and whether and how these processes depend on the large-scale galactic enviro …
- A meta-analysis of the magnetic line broadening in the solar atmosphere
- Asensio Ramos, A.
A multiline Bayesian analysis of the Zeeman broadening in the solar atmosphere is presented. A hierarchical probabilistic model, based on the simple but realistic Milne-Eddington approximation to the solution of the radiative transfer equation is us …