- A Macroscopic Description of a Generalized Self-organized Criticality System: Astrophysical Applications
- Aschwanden, Markus J.
We suggest a generalized definition of self-organized criticality (SOC) systems: SOC is a critical state of a nonlinear energy dissipation system that is slowly and continuously driven toward a critical value of a system-wide instability threshold, …
- Search for Gamma-ray-emitting Active Galactic Nuclei in the Fermi-LAT Unassociated Sample Using Machine Learning
- Doert, M.; Errando, M.
The second Fermi-LAT source catalog (2FGL) is the deepest all-sky survey available in the gamma-ray band. It contains 1873 sources, of which 576 remain unassociated. Machine-learning algorithms can be trained on the gamma-ray properties of known act …
- Probing Topological Relations between High-density and Low-density Regions of 2MASS with Hexagon Cells
- Wu, Yongfeng; Xiao, Weike
We introduced a new two-dimensional (2D) hexagon technique for probing the topological structure of the universe in which we mapped regions of the sky with high and low galaxy densities onto a 2D lattice of hexagonal unit cells. We defined filled ce …
- Mining the VVV: star formation and embedded clusters
- Solin, O.; Haikala, L.; Ukkonen, E.
Survey (VVV) catalogue data. Methods: The method fits a mixture model of Gaussian densities and background noise and uses the expectation maximization algorithm to pre-filtered near-infrared survey stellar catalogue data; it was developed by the a …
- Galaxy and Mass Assembly (GAMA): fine filaments of galaxies detected within voids
- Alpaslan, Mehmet; Robotham, Aaron S. G.; Obreschkow, Danail; Penny, Samantha; Driver, Simon; Norberg, Peder; Brough, Sarah; Brown, Michael; Cluver, Michelle; Holwerda, Benne; Hopkins, Andrew M.; van Kampen, Eelco; Kelvin, Lee S.; Lara-Lopez, Maritza A.; Liske, Jochen; Loveday, Jon; Mahajan, Smriti; Pimbblet, Kevin
Based on data from the Galaxy and Mass Assembly (GAMA) survey, we report on the discovery of structures that we refer to as `tendrils’ of galaxies: coherent, thin chains of galaxies that are rooted in filaments and terminate in neighbouring filament …
- Puoko-nui: a flexible high-speed photometric system
- Chote, P.; Sullivan, D. J.; Brown, R.; Harrold, S. T.; Winget, D. E.; Chandler, D. W.
We describe a portable CCD-based instrumentation system designed to efficiently undertake high time precision fast photometry. The key components of the system are (1) an externally triggered commercial frame-transfer CCD, (2) a custom Global Positi …
- PDM13: a new graphical interfaced program for frequency analysis
- Zalian, C.; Chadid, M.; Stellingwerf, R. F.
Frequency analysis of pulsating stars can be performed via several algorithms. Still, each of these methods has its own specific flaws which advocates for the use of as many tools as possible. However, the lack of simple programs with straightforwar …
- Hierarchical reverberation mapping
- Brewer, Brendon J.; Elliott, Tom M.
Reverberation mapping (RM) is an important technique in studies of active galactic nuclei (AGN). The key idea of RM is to measure the time lag τ between variations in the continuum emission from the accretion disc and subsequent response of the bro …
- A novel variability-based method for quasar selection: evidence for a rest-frame ˜54 d characteristic time-scale
- Graham, Matthew J.; Djorgovski, S. G.; Drake, Andrew J.; Mahabal, Ashish A.; Chang, Melissa; Stern, Daniel; Donalek, Ciro; Glikman, Eilat
We compare quasar-selection techniques based on their optical variability using data from the Catalina Real-time Transient Survey (CRTS). We introduce a new technique based on Slepian wavelet variance (SWV) that shows comparable or better performanc …
- Weighing the Giants – I. Weak-lensing masses for 51 massive galaxy clusters: project overview, data analysis methods and cluster images
- von der Linden, Anja; Allen, Mark T.; Applegate, Douglas E.; Kelly, Patrick L.; Allen, Steven W.; Ebeling, Harald; Burchat, Patricia R.; Burke, David L.; Donovan, David; Morris, R. Glenn; Blandford, Roger; Erben, Thomas; Mantz, Adam
This is the first in a series of papers in which we measure accurate weak-lensing masses for 51 of the most X-ray luminous galaxy clusters known at redshifts 0.15 ≲ zCl ≲ 0.7, in order to calibrate X-ray and other mass proxies for cosmological c …
- UVMULTIFIT: A versatile tool for fitting astronomical radio interferometric data
- Martí-Vidal, I.; Vlemmings, W. H. T.; Muller, S.; Casey, S.
Context. The analysis of astronomical interferometric data is often performed on the images obtained after deconvolving the interferometer’s point spread function. This strategy can be understood (especially for cases of sparse arrays) as fitting mo …
- 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 …
- Targeting supermassive black hole binaries and gravitational wave sources for the pulsar timing array
- Rosado, Pablo A.; Sesana, Alberto
This paper presents a technique to search for supermassive black hole binaries (MBHBs) in the Sloan Digital Sky Survey (SDSS). The search is based on the peculiar properties of merging galaxies that are found in a mock galaxy catalogue from the Mill …
- Properties of starless and prestellar cores in Taurus revealed by Herschel: SPIRE/PACS imaging
- Marsh, K. A.; Griffin, M. J.; Palmeirim, P.; André, Ph.; Kirk, J.; Stamatellos, D.; Ward-Thompson, D.; Roy, A.; Bontemps, S.; Francesco, J. Di; Elia, D.; Hill, T.; Könyves, V.; Motte, F.; Nguyen-Luong, Q.; Peretto, N.; Pezzuto, S.; Rivera-Ingraham, A.; Schneider, N.; Spinoglio, L.; White, G.
The density and temperature structures of dense cores in the L1495 cloud of the Taurus star-forming region are investigated using Herschel Spectral and Photometric Imaging Receiver and Photodetector Array Camera and Spectrometer images in the 70, 16 …
- Cosmic star formation probed via parametric stack-fitting of known sources to radio imaging
- Roseboom, I. G.; Best, P. N.
The promise of multiwavelength astronomy has been tempered by the large disparity in sensitivity and resolution between different wavelength regimes. Here, we present a statistical approach which attempts to overcome this by fitting parametric model …
- 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 …
- 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 …