Journal article

Publication Details

Author(s): Bachetti M, Harrison FA, Cook R, Tomsick J, Schmid C, Grefenstette BW, Barret D, Boggs SE, Christensen FE, Craig WW, Fabian AC, Fuerst F, Gandhi P, Hailey CJ, Kara E, Maccarone TJ, Miller JM, Pottschmidt K, Stern D, Uttley P, Walton DJ, Wilms J, Zhang WW
Journal: Astrophysical Journal
Publisher: American Astronomical Society
Publication year: 2015
Volume: 800
ISSN: 0004-637X
eISSN: 1538-4357


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 (similar to 2.5msec) and varies event-to-event by a few percent. The most obvious effect is a distortion of the white noise level in the power density spectrum (PDS) that cannot be easily modeled with 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 cospectrum, the real part of the cross PDS, 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 ratio relative to what would be achieved using more standard techniques. We apply this technique to NuSTAR observations of the black hole binaries GX 339-4, Cyg X-1, and GRS 1915+105.

FAU Authors / FAU Editors

Schmid, Christian Dr.
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Wilms, Jörn Prof. Dr.
Professur für Astronomie und Astrophysik

External institutions with authors

California Institute of Technology (Caltech)
Columbia University
Durham University
National Aeronautics and Space Administration (NASA)
Technical University of Denmark / Danmarks Tekniske Universitet (DTU)
Texas Tech University (TTU)
University of Amsterdam
University of California, Berkeley
University of Cambridge
University of Maryland, Baltimore County
University of Michigan
University of Toulouse

How to cite

Bachetti, M., Harrison, F.A., Cook, R., Tomsick, J., Schmid, C., Grefenstette, B.W.,... Zhang, W.W. (2015). NO TIME FOR DEAD TIME: TIMING ANALYSIS OF BRIGHT BLACK HOLE BINARIES WITH NuSTAR. Astrophysical Journal, 800.

Bachetti, Matteo, et al. "NO TIME FOR DEAD TIME: TIMING ANALYSIS OF BRIGHT BLACK HOLE BINARIES WITH NuSTAR." Astrophysical Journal 800 (2015).


Last updated on 2019-23-08 at 08:32