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Cyclotron resonant scattering feature simulations. I. Thermally averaged cyclotron scattering cross sections, mean free photon-path tables, and electron momentum sampling

Schwarm, F.-W. and Schönherr, G. and Falkner, S. and Pottschmidt, K. and Wolff, M. T. and Becker, P. A. and Sokolova-Lapa, E. and Klochkov, D. and Ferrigno, C. and Fürst, F. and Hemphill, P. B. and Marcu-Cheatham, D. M. and Dauser, T. and Wilms, J. (2017) Cyclotron resonant scattering feature simulations. I. Thermally averaged cyclotron scattering cross sections, mean free photon-path tables, and electron momentum sampling. Astronomy and Astrophysics, 597 . Art. No. A3. ISSN 0004-6361. https://resolver.caltech.edu/CaltechAUTHORS:20170310-120734693

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Abstract

Context. Electron cyclotron resonant scattering features (CRSFs) are observed as absorption-like lines in the spectra of X-ray pulsars. A significant fraction of the computing time for Monte Carlo simulations of these quantum mechanical features is spent on the calculation of the mean free path for each individual photon before scattering, since it involves a complex numerical integration over the scattering cross section and the (thermal) velocity distribution of the scattering electrons. Aims. We aim to numerically calculate interpolation tables which can be used in CRSF simulations to sample the mean free path of the scattering photon and the momentum of the scattering electron. The tables also contain all the information required for sampling the scattering electron’s final spin. Methods. The tables were calculated using an adaptive Simpson integration scheme. The energy and angle grids were refined until a prescribed accuracy is reached. The tables are used by our simulation code to produce artificial CRSF spectra. The electron momenta sampled during these simulations were analyzed and justified using theoretically determined boundaries. Results. We present a complete set of tables suited for mean free path calculations of Monte Carlo simulations of the cyclotron scattering process for conditions expected in typical X-ray pulsar accretion columns (0.01 ≤ B/B_(crit) ≤ 0.12, where B_(crit) = 4.413 × 10^(13) G, and 3 keV ≤ k_BT ≤ 15 keV). The sampling of the tables is chosen such that the results have an estimated relative error of at most 1/15 for all points in the grid. The tables are available online (see link in footnote, page 1).


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1051/0004-6361/201629352DOIArticle
http://www.aanda.org/articles/aa/abs/2017/01/aa29352-16/aa29352-16.htmlPublisherArticle
Additional Information:© ESO, 2016. Received: 20 July 2016. Accepted: 30 August 2016. Published online 19 December 2016. This work has been partially funded by the Deutsche Forschungsgemeinschaft under DFG grant number WI 1860/11-1 and by the Deutsches Zentrum für Luft- und Raumfahrt under DLR grant numbers 50 OR 1113, 50 OR 1207, and 50 OR 1411. M.T.W. is supported by the Chief of Naval Research and by the National Aeronautics and Space Administration Astrophysical Data Analysis Program. We thank the International Space Science Institute in Bern for inspiring team meetings. The fruitful discussions within the MAGNET collaboration also had a very positive impact on this work.
Funders:
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)WI 1860/11-1
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50 OR 1113
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50 OR 1207
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50 OR 1411
Chief of Naval ResearchUNSPECIFIED
NASAUNSPECIFIED
Subject Keywords:X-rays: binaries / stars: neutron / methods: numerical
Record Number:CaltechAUTHORS:20170310-120734693
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170310-120734693
Official Citation:Cyclotron resonant scattering feature simulations - I. Thermally averaged cyclotron scattering cross sections, mean free photon-path tables, and electron momentum sampling F.-W. Schwarm, G. Schönherr, S. Falkner, K. Pottschmidt, M. T. Wolff, P. A. Becker, E. Sokolova-Lapa, D. Klochkov, C. Ferrigno, F. Fürst, P. B. Hemphill, D. M. Marcu-Cheatham, T. Dauser and J. Wilms A&A, 597 (2017) A3 DOI: https://doi.org/10.1051/0004-6361/201629352
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75027
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:10 Mar 2017 21:11
Last Modified:03 Oct 2019 16:45

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