This Week in Computational Astrophysics
Recent Techniques and Applications

Tuesday, 17 November


Acceleration and collimation of relativistic MHD disk winds

http://www.arxiv.org/abs/0911.3001
O. Porth, C. Fendt
submitted to ApJ
We perform axisymmetric relativistic magnetohydrodynamic (MHD) simulations to investigate the acceleration and collimation of jets and outflows from disks around compact objects.

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17 11 09 - 17:33 | | No comments |


An Efficient Method for Modeling High Magnification Planetary Microlensing Events

http://www.arxiv.org/abs/0911.2703
David P. Bennett
31 pages, including 5 figures, submitted to ApJ
I present a previously unpublished method for calculating light curves for high magnification planetary microlensing events that is designed to be efficient enough to handle complicated microlensing events, which include more than two lens masses and lens orbital motion.

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17 11 09 - 17:24 | | No comments |

Monday, 16 November


A turbulence model for smoothed particle hydrodynamics

http://www.arxiv.org/abs/0911.2523
J. J. Monaghan
34 pages, 11 figures
The aim of this paper is to devise a turbulence model for the particle method Smoothed Particle Hydrodynamics (SPH) which makes few assumptions, conserves linear and angular momentum, satisfies a discrete version of Kelvin's circulation theorem, and is computationally efficient.

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16 11 09 - 13:17 | | No comments |

Sunday, 15 November


The case for AGN feedback in galaxy groups

http://www.arxiv.org/abs/0911.2641
Ian G. McCarthy, Joop Schaye, Trevor J. Ponman, Richard G. Bower, Craig M. Booth, Claudio Dalla Vecchia, Robert A. Crain, Volker Springel, Tom Theuns, Robert P. C. Wiersma
20 pages, 13 figures, submitted to MNRAS
[Abridged] The relatively recent insight that energy input from supermassive black holes (BHs) can have a substantial effect on the star formation rates (SFRs) of galaxies motivates us to examine its effects on the scale of galaxy groups.

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15 11 09 - 21:15 | | No comments |


Spectro-Perfectionism: An Algorithmic Framework for Photon Noise-Limited Extraction of Optical Fiber Spectroscopy

http://www.arxiv.org/abs/0911.2689
Adam S. Bolton (Utah), David J. Schlegel (LBL)
8 pages, 4 figures, emulateapj; submitted to PASP; comments welcome
We describe a new algorithm for the "perfect" extraction of one-dimensional spectra from two-dimensional CCD images of optical fiber spectrographs, based on accurate two-dimensional (2D) forward modeling of the raw pixel data.

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15 11 09 - 21:15 | | No comments |


Turbulence modeling and the physics of the intra-cluster medium

http://www.arxiv.org/abs/0911.2629
L. Iapichino (1), A. Maier (2), W. Schmidt (3), J. C. Niemeyer (3) ((1) ZAH/ITA, Univ. Heidelberg; (2) Lehrstuhl für Astronomie, Univ. Würzburg; (3) Institut für Astrophysik, Univ. Göttingen)
To appear in the proceedings of the "Invisible Universe International Conference"
FEARLESS (Fluid mEchanics with Adaptively Refined Large Eddy SimulationS) is a new numerical scheme arising from the combined use of subgrid scale (SGS) model for turbulence at the unresolved length scales and adaptive mesh refinement (AMR) for resolving the large scales.

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15 11 09 - 21:14 | | No comments |


Discarded low energy particles in extensive air shower simulations: Effect on the shower Energy Deposit

http://www.arxiv.org/abs/0911.2535
M. J. Tueros
15 pages, 7 figures, submited to Journal of physics G
The simulation of particle cascades initiated in the atmosphere by ultra high energy cosmic ray particles involves the generation and propagation of a huge amount of particles.

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15 11 09 - 21:13 | | No comments |


Detecting the orientation of magnetic fields in galaxy clusters

http://www.arxiv.org/abs/0911.2476
Christoph Pfrommer (1), L. Jonathan Dursi (2, 1), ((1) CITA, (2) SciNet)
this http URL
Clusters of galaxies, filled with hot, magnetised plasma, are the largest bound objects in existence and an important touchstone in understanding the formation of structures in our Universe.

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15 11 09 - 21:00 | | No comments |


Detecting the orientation of magnetic fields in galaxy clusters

http://www.arxiv.org/abs/0911.2476
Christoph Pfrommer (1), L. Jonathan Dursi (2, 1), ((1) CITA, (2) SciNet)
this http URL
Clusters of galaxies, filled with hot, magnetised plasma, are the largest bound objects in existence and an important touchstone in understanding the formation of structures in our Universe.

(more)

15 11 09 - 20:57 | | No comments |


Detecting the orientation of magnetic fields in galaxy clusters

http://www.arxiv.org/abs/0911.2476
Christoph Pfrommer (1), L. Jonathan Dursi (2, 1), ((1) CITA, (2) SciNet)
this http URL
Clusters of galaxies, filled with hot, magnetised plasma, are the largest bound objects in existence and an important touchstone in understanding the formation of structures in our Universe.

(more)

15 11 09 - 20:44 | | No comments |


Interactions between a massive planet and a disc

http://www.arxiv.org/abs/0911.2468
Pau Amaro-Seoane, Ignasi Ribas, Ulf Loeckmann, Holger Baumgardt
Two-page contribution to "Pathways towards habitable planets". An extended version of this note will be soon published in ApJ (needs asp2006.sty, psfig.sty and picins.sty, included)
We analyse the potential migration of massive planets forming far away from an inner planetary system.

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15 11 09 - 20:43 | | No comments |

Thursday, 12 November


Simulations of momentum feedback by black hole winds

http://www.arxiv.org/abs/0911.2434
Sergei Nayakshin, Chris Power (Leicester)
17 pages, to appear in MNRAS
The observed super-massive black hole (SMBH) mass -- galaxy velocity dispersion ($M_{\rm bh} - \sigma$) correlation may be established when winds/outflows from the SMBH drive gas out of the potential wells of classical bulges.

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12 11 09 - 22:40 | | No comments |


Scaled solar tracks and isochrones in a large region of the Z-Y plane. II. From 2.5 to 20 solar masses

http://www.arxiv.org/abs/0911.2419
G. Bertelli (1), E. Nasi (1), L. Girardi (1), P. Marigo (2) ((1) INAF - Padova Astronomical Observatory, (2) Astronomical Department, Padova University)
17 pages, 18 figures, accepted for publication in A&A
We extend our theoretical computations for low-mass stars to intermediate-mass and massive stars, for which few databases exist in the literature.

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12 11 09 - 22:39 | | No comments |


Gas Accretion from a Circumbinary Disk

http://www.arxiv.org/abs/0911.2032
Tomoyuki Hanawa, Yasuhiro Ochi, Koichi Ando
41 pages, 25 PostScript figures, uses AASTeX, to appear in ApJ
A new computational scheme is developed to study gas accretion from a circumbinary disk.

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12 11 09 - 22:35 | | No comments |


Fast and Large Volume Simulations of the 21 cm Signal from the Reionization and pre-Reionization Epochs

http://www.arxiv.org/abs/0911.2219
M. G. Santos (1), L. Ferramacho (1), M. B. Silva (1), A. Amblard (2), A. Cooray (2) ((1) CENTRA - IST, (2) UC Irvine)
14 pages and 15 figures
While limited to low spatial resolution, the next generation low-frequency radio interferometers that target 21 cm observations during the era of reionization and prior will have instantaneous fields-of-view that are many tens of square degrees on the sky.

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12 11 09 - 22:32 | | No comments |

Tuesday, 10 November


Radiation thermo-chemical models of protoplanetary disks II. Line diagnostics

http://www.arxiv.org/abs/0911.1949
I. Kamp, I. Tilling, P. Woitke, W.-F. Thi, M. Hogerheijde
accepted for publication in A&A
Methods.

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10 11 09 - 22:21 | | No comments |


Solar-Terrestrial Simulations of CMEs with a Realistic Initiation Mechanism: Case Study for Active Region 10069

http://www.arxiv.org/abs/0911.1895
N. Lugaz, I. I. Roussev, I. V. Sokolov, C. Jacobs
4 pages, 2 figures, refereed proceedings for Solar Wind 12
Most simulations of coronal mass ejections (CMEs) to date either focus on the interplanetary propagation of a giant plasma "blob" without paying too much attention to its origin and to the formation process or they focus on the complex evolution of the coronal magnetic field due to (sub-)photospheric motions which result in an eruption.

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10 11 09 - 22:20 | | No comments |


Exploring the $P_{cyc}$ vs $P_{rot}$ relation with flux transport dynamo models of solar-like stars

http://www.arxiv.org/abs/0911.1947
L. Jouve (1,2), B.P. Brown (3), A.S. Brun (1,3)
12 pages, 8 figures, accepted for publication by A&A 1: AIM, CEA/DSM-CNRS-Univ. Paris 7, IRFU/SAp, France, 2: D.A.M.T.P., Centre for Mathematical Sciences, Univ. of Cambridge, UK, 3: JILA and Department of Astrophysical and Planetary Sciences, Univ. of Colorado, USA
Aims: To understand stellar magnetism and to test the validity of the Babcock-Leighton flux transport mean field dynamo models with stellar activity observations Methods: 2-D mean field dynamo models at various rotation rates are computed with the STELEM code to study the sensitivity of the activity cycle period and butterfly diagram to parameter changes and are compared to observational data.

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10 11 09 - 22:20 | | No comments |


Virtual Observatory: Science capabilities and scientific results

http://www.arxiv.org/abs/0911.1878
Evanthia Hatziminaoglou (ESO, Garching)
10 pages, 5 figures, invited talk, proceedings of the 9th Hellenic Astronomical Society Conference, Athens, 20-24 September 2009
The virtual observatory (VO) is a collection of interoperable data archives, tools and applications that together form an environment in which original astronomical research can be carried out.

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10 11 09 - 22:19 | | No comments |


Revisiting 2D Numerical Models for the 19th century outbursts of $\eta$ Carinae

http://www.arxiv.org/abs/0911.1808
R.F. González, A.M. Villa, G.C. Gómez, E.M. de Gouveia Dal Pino, A.C. Raga, J. Cantó, P.F. Velázquez, E. de la Fuente
accepted for publication in MNRAS
We present here new results of two-dimensional hydrodynamical simulations of the eruptive events of the 1840s (the great) and the 1890s (the minor) eruptions suffered by the massive star $\eta$ Car.

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10 11 09 - 22:19 | | No comments |


Structure, Kinematics, and Chemical Enrichment Patterns after Major Gas-Rich Disc-Disc Mergers

http://www.arxiv.org/abs/0911.1801
Simon Richard, Chris B. Brook, Hugo Martel, Daisuke Kawata, Brad K. Gibson, Patricia Sanchez-Blazquez
17 pages, 20 figures, to be published in MNRAS
We used an N-body smoothed particle hydrodynamics algorithm, with a detailed treatment of star formation, supernovae feedback, and chemical enrichment, to perform eight simulations of mergers between gas-rich disc galaxies.

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10 11 09 - 22:18 | | No comments |


Dependence of the Star Formation Efficiency on the Parameters of Molecular Cloud Formation Simulations

http://www.arxiv.org/abs/0911.1795
Yetli Rosas-Guevara, Enrique Vazquez-Semadeni, Gilberto C. Gomez, A.-Katharina Jappsen
19 pages, submitted to MNRAS
We investigate the response of the star formation efficiency (SFE) to the main parameters of simulations of molecular cloud formation by the collision of warm diffuse medium (WNM) cylindrical streams, neglecting stellar feedback and magnetic fields.

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10 11 09 - 22:17 | | No comments |


Chemical Evolution in Hierarchical Models of Cosmic Structure II: The Formation of the Milky Way Stellar Halo and the Distribution of the Oldest Stars

http://www.arxiv.org/abs/0911.1786
Jason Tumlinson (STScI)
Submitted to ApJ, 22 pages emulateapj, 15 color figures
This paper presents theoretical star formation and chemical enrichment histories for the stellar halo of the Milky Way based on new chemodynamical modeling.

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10 11 09 - 22:15 | | No comments |


Computing the Bayesian Evidence from a Markov Chain Monte Carlo Simulation of the Posterior Distribution

http://www.arxiv.org/abs/0911.1777
Martin D. Weinberg
22 pages, 6 figures, submitted to Bayesian Analysis
Computation of the marginal likelihood or "Bayesian Evidence" from a simulated posterior distribution is central to Bayesian model selection but is fraught with difficulty.

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10 11 09 - 22:15 | | No comments |

Monday, 09 November


A Simultaneous Stacking and Deblending Algorithm for Astronomical Images

http://www.arxiv.org/abs/0911.1592
Peter Kurczynski, Eric Gawiser
submitted to The Astronomical Journal. 18 pages, 6 figures
Stacking analysis is a means of detecting faint sources using a priori position information to estimate an aggregate signal from individually undetected objects.

(more)

09 11 09 - 23:39 | | No comments |

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