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No Time for Dead Time: Timing analysis of bright black hole binaries with NuSTAR

Bachetti, Matteo and Harrison, Fiona A. and Cook, Rick and Tomsick, John and Schmid, Christian and Grefenstette, Brian W. and Barret, Didier and Boggs, Steven E. and Christensen, Finn E. and Craig, William W. and Fabian, Andrew C. and Fürst, Felix and Gandhi, Poshak and Hailey, Charles J. and Kara, Erin and Maccarone, Thomas J. and Miller, Jon M. and Pottschmidt, Katja and Stern, Daniel and Uttley, Phil and Walton, Dominic J. and Wilms, Jörn and Zhang, William W. (2015) No Time for Dead Time: Timing analysis of bright black hole binaries with NuSTAR. Astrophysical Journal, 800 (2). Art. No. 109. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20141211-085027843

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Abstract

Timing of high-count rate sources with the NuSTAR Small Explorer Mission requires specialized analysis techniques. NuSTAR was primarily designed for spectroscopic observations of sources with relatively low count-rates rather than for timing analysis of bright objects. The instrumental dead time per event is relatively long (∼2.5 msec), and varies by a few percent event-to-event. The most obvious effect is a distortion of the white noise level in the power density spectrum (PDS) that cannot be modeled easily with the standard techniques due to the variable nature of the dead time. In this paper, we show that it is possible to exploit the presence of two completely independent focal planes and use the cross power density spectrum to obtain a good proxy of the white noise-subtracted PDS. Thereafter, one can use a Monte Carlo approach to estimate the remaining effects of dead time, namely a frequency-dependent modulation of the variance and a frequency-independent drop of the sensitivity to variability. In this way, most of the standard timing analysis can be performed, albeit with a sacrifice in signal to noise relative to what would be achieved using more standard techniques. We apply this technique to NuSTAR observations of the black hole binaries GX339−4, CygX-1 and GRS 1915+105.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0004-637X/800/2/109DOIArticle
http://iopscience.iop.org/0004-637X/800/2/109PublisherArticle
http://arxiv.org/abs/1409.3248arXivDiscussion Paper
ORCID:
AuthorORCID
Bachetti, Matteo0000-0002-4576-9337
Harrison, Fiona A.0000-0003-2992-8024
Boggs, Steven E.0000-0001-9567-4224
Gandhi, Poshak0000-0003-3105-2615
Stern, Daniel0000-0003-2686-9241
Walton, Dominic J.0000-0001-5819-3552
Additional Information:© 2015 American Astronomical Society. Received 2014 September 9; accepted 2014 December 22; published 2015 February 18. MB and DB wish to acknowledge the support from the Centre National d’Études Spatiales (CNES) and the Centre National de la Recherche Scientifique (CNRS). CS acknowledges funding by the German BMWi under DLR grant numbers 50 QR 0801, 50 QR 0903, and 50 OO 1111. P.G. thanks STFC for support (grant reference ST/J003697/1). This work was supported under NASA Contract No. NNG08FD60C, and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). The timing analysis was executed with Matteo Bachetti’s Libraries and Tools in Python for NuSTAR Timing (MaLTPyNT). This code is available upon request. Most of the plots were produced with the Veusz software by Jeremy Sanders. The authors wish to thank Chris Done, Denis Leahy and Tomaso Belloni for very insightful discussions.
Group:NuSTAR, Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
Centre National d’Études Spatiales (CNES)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50 QR 0801
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50 QR 0903
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50 OO 1111
Science and Technology Facilities Council (STFC) ST/J003697/1
NASANNG08FD60C
NASA/Caltech/JPLUNSPECIFIED
Subject Keywords:X-rays: stars, accretion, accretion disks, black hole physics
Record Number:CaltechAUTHORS:20141211-085027843
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20141211-085027843
Official Citation:No Time for Dead Time: Timing Analysis of Bright Black Hole Binaries with NuSTAR Matteo Bachetti et al. 2015 ApJ 800 109
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:52576
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:11 Dec 2014 21:42
Last Modified:21 Mar 2019 19:00

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