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202 results on '"Nicholas J. Wright"'

1. Classification of Chandra X-Ray Sources in Cygnus OB2

Author

Vinay L. Kashyap, Mario G. Guarcello, Nicholas J. Wright, Jeremy J. Drake, Ettore Flaccomio, Tom L. Aldcroft, Juan F. Albacete Colombo, Kevin Briggs, Francesco Damiani, Janet E. Drew, Eduardo L. Martin, Giusi Micela, Tim Naylor, and Salvatore Sciortino

Subjects
Star forming regions, Catalogs, Astrostatistics, Astrostatistics techniques, Bayesian statistics, Open star clusters, Astrophysics, QB460-466
Abstract

We have devised a predominantly Naive Bayes−based method to classify X-ray sources detected by Chandra in the Cygnus OB2 association into members, foreground objects, and background objects. We employ a variety of X-ray, optical, and infrared characteristics to construct likelihoods using training sets defined by well-measured sources. Combinations of optical photometry from the Sloan Digital Sky Survey ( riz ) and Isaac Newton Telescope Photometric H α Survey ( r _I i _I H α ), infrared magnitudes from United Kingdom Infrared Telescope Deep Sky Survey and Two-Micron All Sky Survey ( JHK ), X-ray quantiles and hardness ratios, and estimates of extinction A _v are used to compute the relative probabilities that a given source belongs to one of the classes. Principal component analysis is used to isolate the best axes for separating the classes for the photometric data, and Gaussian component separation is used for X-ray hardness and extinction. Errors in the measurements are accounted for by modeling as Gaussians and integrating over likelihoods approximated as quartic polynomials. We evaluate the accuracy of the classification by inspection and reclassify a number of sources based on infrared magnitudes, the presence of disks, and spectral hardness induced by flaring. We also consider systematic errors due to extinction. Of the 7924 X-ray detections, 5501 have a total of 5597 optical/infrared matches, including 78 with multiple counterparts. We find that ≈6100 objects are likely association members, ≈1400 are background objects, and ≈500 are foreground objects, with an accuracy of 96%, 93%, and 80%, respectively, with an overall classification accuracy of approximately 95%.

Published
2023
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2. The Chandra Cygnus OB2 Legacy Survey: Design and X-Ray Point-source Catalog

Author

Nicholas J. Wright, Jeremy J. Drake, Mario G. Guarcello, Tom L. Aldcroft, Vinay L. Kashyap, Francesco Damiani, Joe DePasquale, and Antonella Fruscione

Subjects
X-rays stars, pre-main sequence stars, massive stars, Astrophysics, QB460-466
Abstract

The Cygnus OB2 association is the largest concentration of young and massive stars within 2 kpc of the Sun, including an estimated ∼65 O-type stars and hundreds of OB stars. The Chandra Cygnus OB2 Legacy Survey is a large imaging program undertaken with the Advanced CCD Imaging Spectrometer on board the Chandra X-ray Observatory. The survey has imaged the central 0.5 deg ^2 of the Cyg OB2 association with an effective exposure of ∼120 ks and an outer 0.35 deg ^2 area with an exposure of ∼60 ks. Here we describe the survey design and observations, discuss the data reduction and source detection, and present a catalog of ∼8000 X-ray point sources. The survey design employs a grid of 36 heavily (∼50%) overlapping pointings, a method that overcomes Chandra's low off-axis sensitivity and produces a highly uniform exposure over the inner 0.5 deg ^2 . The full X-ray catalog is described here and is made available online.

Published
2023
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3. Simulating the Sensitivity to Stellar Point Sources of Chandra X-Ray Observations

Author

Nicholas J. Wright, Jeremy J. Drake, Mario G. Guarcello, Vinay L. Kashyap, and Andreas Zezas

Subjects
X-ray stars, Pre-main sequence stars, Astrophysics, QB460-466
Abstract

The Chandra Cygnus OB2 Legacy Survey is a wide and deep X-ray survey of the nearby and massive Cygnus OB2 association. The survey has detected ∼8000 X-ray sources, the majority of which are pre-main-sequence X-ray-emitting young stars in the association itself. To facilitate quantitative scientific studies of these sources, as well as the underlying OB association, it is important to understand the sensitivity of the observations and the level of completeness the observations have obtained. Here we describe the use of a hierarchical Monte Carlo simulation to achieve this goal by combining the empirical properties of the observations, analytic estimates of the source verification process, and an extensive set of source detection simulations. We find that our survey reaches a 90% completeness level for a pre-main-sequence population at the distance of Cyg OB2 at an X-ray luminosity of 4 × 10 ^30 erg s ^−1 and a stellar mass of 1.3 M _⊙ for a randomly distributed population. For a spatially clustered population such as Cyg OB2 the 90% completeness level is reached at 1.1 M _⊙ instead, as the sources are more concentrated in areas of our survey with a high exposure. These simulations can easily be adapted for use with other X-ray observations and surveys, and we provide X-ray detection efficiency curves for a very wide array of source and background properties to allow these simulations to be easily exploited by other users.

Published
2023
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31. The Gaia-ESO Survey: empirical estimates of stellar ages from lithium equivalent widths (<scp>eagles</scp>)

Author

R D Jeffries, R J Jackson, Nicholas J Wright, G Weaver, G Gilmore, S Randich, A Bragaglia, A J Korn, R Smiljanic, K Biazzo, A R Casey, A Frasca, A Gonneau, G Guiglion, L Morbidelli, L Prisinzano, G G Sacco, G Tautvaišienė, C C Worley, and S Zaggia

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), fundamental parameters [stars], FOS: Physical sciences, Astronomy and Astrophysics, pre-main-sequence [stars], Astrophysics - Astrophysics of Galaxies, abundances [stars], Astronomi, astrofysik och kosmologi, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, evolution [stars], Astrophysics of Galaxies (astro-ph.GA), Astronomy, Astrophysics and Cosmology, general [open clusters and associations], Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics - Earth and Planetary Astrophysics
Abstract

We present an empirical model of age-dependent photospheric lithium depletion, calibrated using a large, homogeneously-analysed sample of 6200 stars in 52 open clusters, with ages from 2--6000 Myr and $-0.3, Accepted for publication in Monthly Notices of the Royal Astronomical Society. Code available at https://github.com/robdjeff/eagles

Published
2023
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40. The structure and 3D kinematics of vela OB2

Author

Joseph J Armstrong, Nicholas J Wright, R D Jeffries, R J Jackson, and Tristan Cantat-Gaudin

Subjects
Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

The kinematics of stars in OB associations can provide insights into their formation, dynamical evolution, and eventual fate. The low-mass stellar content of OB associations are sufficiently numerous as to provide a detailed sampling of their kinematic properties, however spectroscopy is required to confirm the youth of individual stars and to get 3D kinematics. In this paper we present and analyse results from a large spectroscopic survey of Vela OB2 conducted using 2dF/HERMES on the AAT. This spectroscopy is used to confirm the youth of candidate young stars and determine radial velocities, which are combined with proper motions and parallaxes from Gaia to measure 3-dimensional positions and velocities. We identify multiple separate kinematic groups in the region, for which we measure velocity dispersions and infer their virial states. We measure expansion rates for all these groups and find strong evidence for anisotropic expansion in the Vela OB2 association of at least 11$\sigma$ significance in all three dimensions, as well as some evidence for expansion in the $\gamma$ Vel and P Puppis clusters. We trace back the motions of these groups into the past and find that the open cluster NGC 2547 is an interloper in the Vela OB2 region and actually formed $>$100 pc away from the association. We conclude that Vela OB2 must have formed with considerable spatial and kinematic substructure over a timescale of $\sim$10 Myr, with clear temporal substructure within the association, but no clear evidence for an age gradient., Comment: 19 pages, 13 figures, 4 tables, submitted to MNRAS

Published
2022
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41. Not all applications have boring communication patterns: Profiling message matching with BMM

Author

David Trebotich, Brandon Cook, Noel Keen, Naveen Ravichandrasekaran, Taylor Groves, Nicholas J. Wright, Duncan Roweth, Bob Alverson, and Keith Underwood

Subjects
Profiling (computer programming), Matching (statistics), Artificial Intelligence and Image Processing, Computer Networks and Communications, Computer science, offload NIC, tag matching, computer.software_genre, Computer Science Applications, Theoretical Computer Science, Computer Software, message matching, Computational Theory and Mathematics, MPI, Data mining, Distributed Computing, computer, Software
Abstract

Message matching within MPI is an important performance consideration for applications that utilize two-sided semantics. In this work, we present an instrumentation of the CrayMPI library that allows the collection of detailed message-matching statistics as well as an implementation of hashed matching in software. We use this functionality to profile key DOE applications with complex communication patterns to determine under what circumstances an application might benefit from hardware offload capabilities within the NIC to accelerate message matching. We find that there are several applications and libraries that exhibit sufficiently long match list lengths to motivate a Binned Message Matching approach.

Published
2023

48. The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation

Author

Shoko Jin, Scott C Trager, Gavin B Dalton, J Alfonso L Aguerri, J E Drew, Jesús Falcón-Barroso, Boris T Gänsicke, Vanessa Hill, Angela Iovino, Matthew M Pieri, Bianca M Poggianti, D J B Smith, Antonella Vallenari, Don Carlos Abrams, David S Aguado, Teresa Antoja, Alfonso Aragón-Salamanca, Yago Ascasibar, Carine Babusiaux, Marc Balcells, R Barrena, Giuseppina Battaglia, Vasily Belokurov, Thomas Bensby, Piercarlo Bonifacio, Angela Bragaglia, Esperanza Carrasco, Ricardo Carrera, Daniel J Cornwell, Lilian Domínguez-Palmero, Kenneth J Duncan, Benoit Famaey, Cecilia Fari na, Oscar A Gonzalez, Steve Guest, Nina A Hatch, Kelley M Hess, Matthew J Hoskin, Mike Irwin, Johan H Knapen, Sergey E Koposov, Ulrike Kuchner, Clotilde Laigle, Jim Lewis, Marcella Longhetti, Sara Lucatello, Jairo Méndez-Abreu, Amata Mercurio, Alireza Molaeinezhad, Maria Monguió, Sean Morrison, David N A Murphy, Luis Peralta de Arriba, Isabel Pérez, Ignasi Pérez-Ràfols, Sergio Picó, Roberto Raddi, Mercè Romero-Gómez, Frédéric Royer, Arnaud Siebert, George M Seabroke, Debopam Som, David Terrett, Guillaume Thomas, Roger Wesson, C Clare Worley, Emilio J Alfaro, Carlos Allende Prieto, Javier Alonso-Santiago, Nicholas J Amos, Richard P Ashley, Lola Balaguer-Nú nez, Eduardo Balbinot, Michele Bellazzini, Chris R Benn, Sara R Berlanas, Edouard J Bernard, Philip Best, Daniela Bettoni, Andrea Bianco, Georgia Bishop, Michael Blomqvist, Corrado Boeche, Micol Bolzonella, Silvia Bonoli, Albert Bosma, Nikolay Britavskiy, Gianni Busarello, Elisabetta Caffau, Tristan Cantat-Gaudin, Alfred Castro-Ginard, Guilherme Couto, Juan Carbajo-Hijarrubia, David Carter, Laia Casamiquela, Ana M Conrado, Pablo Corcho-Caballero, Luca Costantin, Alis Deason, Abel de Burgos, Sabrina De Grandi, Paola Di Matteo, Jesús Domínguez-Gómez, Ricardo Dorda, Alyssa Drake, Rajeshwari Dutta, Denis Erkal, Sofia Feltzing, Anna Ferré-Mateu, Diane Feuillet, Francesca Figueras, Matteo Fossati, Elena Franciosini, Antonio Frasca, Michele Fumagalli, Anna Gallazzi, Rubén García-Benito, Nicola Gentile Fusillo, Marwan Gebran, James Gilbert, T M Gledhill, Rosa M González Delgado, Robert Greimel, Mario Giuseppe Guarcello, Jose Guerra, Marco Gullieuszik, Christopher P Haines, Martin J Hardcastle, Amy Harris, Misha Haywood, Amina Helmi, Nauzet Hernandez, Artemio Herrero, Sarah Hughes, Vid Irsic, Pascale Jablonka, Matt J Jarvis, Carme Jordi, Rohit Kondapally, Georges Kordopatis, Jens-Kristian Krogager, Francesco La Barbera, Man I Lam, Søren S Larsen, Bertrand Lemasle, Ian J Lewis, Emilie Lhomé, Karin Lind, Marcello Lodi, Alessia Longobardi, Ilaria Lonoce, Laura Magrini, Jesús Maíz Apellániz, Olivier Marchal, Amparo Marco, Nicolas F Martin, Tadafumi Matsuno, Sophie Maurogordato, Paola Merluzzi, Jordi Miralda-Escudé, Emilio Molinari, Giacomo Monari, Lorenzo Morelli, Christopher J Mottram, Tim Naylor, Ignacio Negueruela, Jose Onorbe, Elena Pancino, Sébastien Peirani, Reynier F Peletier, Lucia Pozzetti, Monica Rainer, Pau Ramos, Shaun C Read, Elena Maria Rossi, Huub J A Röttgering, Jose Alberto Rubi no-Martín, Jose Sabater Montes, José San Juan, Nicoletta Sanna, Ellen Schallig, Ricardo P Schiavon, Mathias Schultheis, Paolo Serra, Timothy W Shimwell, Sergio Simón-Díaz, Russell J Smith, Rosanna Sordo, Daniele Sorini, Caroline Soubiran, Else Starkenburg, Iain A Steele, John Stott, Remko Stuik, Eline Tolstoy, Crescenzo Tortora, Maria Tsantaki, Mathieu Van der Swaelmen, Reinout J van Weeren, Daniela Vergani, Marc A W Verheijen, Kristiina Verro, Jorick S Vink, Miguel Vioque, C Jakob Walcher, Nicholas A Walton, Christopher Wegg, Anne-Marie Weijmans, Wendy L Williams, Andrew J Wilson, Nicholas J Wright, Theodora Xylakis-Dornbusch, Kris Youakim, Stefano Zibetti, Cristina Zurita, Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of St Andrews. School of Physics and Astronomy, University of St Andrews. Centre for Contemporary Art, Universidad de Alicante. Departamento de Física Aplicada, Universidad de Alicante. Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, and Astrofísica Estelar (AE)

Subjects
Astrofísica, Cosmology and Nongalactic Astrophysics (astro-ph.CO), NDAS, FOS: Physical sciences, Surveys, surveys, QB Astronomy, spectrographs [Instrumentation], observations [Cosmology], Instrumentation and Methods for Astrophysics (astro-ph.IM), Galaxy: general, stars: general, Solar and Stellar Astrophysics (astro-ph.SR), general [Galaxy], QC, QB, instrumentation: spectrographs, general [Stars], Análisis de datos, Instrumentation spectrographs, Astronomy and Astrophysics, general [Galaxies], galaxies: general, Astrophysics - Astrophysics of Galaxies, QC Physics, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), MCP, cosmology: observations, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, will see first light in late 2022. WEAVE comprises a new 2-degree field-of-view prime-focus corrector system, a nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and a single large IFU. These fibre systems feed a dual-beam spectrograph covering the wavelength range 366$-$959\,nm at $R\sim5000$, or two shorter ranges at $R\sim20\,000$. After summarising the design and implementation of WEAVE and its data systems, we present the organisation, science drivers and design of a five- to seven-year programme of eight individual surveys to: (i) study our Galaxy's origins by completing Gaia's phase-space information, providing metallicities to its limiting magnitude for $\sim$3 million stars and detailed abundances for $\sim1.5$ million brighter field and open-cluster stars; (ii) survey $\sim0.4$ million Galactic-plane OBA stars, young stellar objects and nearby gas to understand the evolution of young stars and their environments; (iii) perform an extensive spectral survey of white dwarfs; (iv) survey $\sim400$ neutral-hydrogen-selected galaxies with the IFUs; (v) study properties and kinematics of stellar populations and ionised gas in $z1$ million spectra of LOFAR-selected radio sources; (viii) trace structures using intergalactic/circumgalactic gas at $z>2$. Finally, we describe the WEAVE Operational Rehearsals using the WEAVE Simulator., 41 pages, 27 figures, accepted for publication by MNRAS

Published
2023
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