The spectral-timing analysis of Cygnus X-1 with Insight-HXMT

Zhou M, Grinberg , Bu QC, Santangelo A, Cangemi F, Diez CM, König O, Ji L, Nowak MA, Pottschmidt K, Rodriguez J, Wilms J, Zhang S, Qu JL, Zhang SN (2022)

Publication Type: Journal article

Publication year: 2022

Journal

Astronomy & Astrophysics EDP Sciences

Book Volume: 666

DOI: 10.1051/0004-6361/202244240

Abstract

Cygnus X-1, as the first discovered black hole binary, is a key source for understanding the mechanisms of state transitions and the scenarios of accretion in extreme gravity fields. We present a spectral-timing analysis of observations taken with the Insight-Hard X-ray Modulation Telescope (HXMT) mission, focusing on the spectral-state-dependent timing properties in the broad energy range of 1-150 keV, thus extending previous studies based on Rossi X-ray Timing Explorer (RXTE) to both lower and higher energies. Our main results are the following: (a) We successfully use a simple empirical model to fit all spectra, confirming that the reflection component is stronger in the soft state than in the hard state. (b) The evolution of the total fractional root mean square (rms) depends on the selected energy band and the spectral shape, which is a direct result of the evolution of the power spectral densities (PSDs). (c) In the hard/intermediate state, we see clear short-term variability features and a positive correlation between the central frequencies of the variability components and the soft photon index Gamma(1), which we also see at energies above 15 keV. In the soft state, the power spectrum is instead dominated by red noise. These behaviors can be traced to at least 90 keV. (d) Finally, the coherence and the phase-lag spectra show different behaviors, depending on the different spectral shapes.

Authors with CRIS profile

Ole König Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut Jörn Wilms Lehrstuhl für Astronomie und Astrophysik

Involved external institutions

Eberhard Karls Universität Tübingen DE Germany (DE) European Space Research and Technology Centre (ESTEC, ESA) NL Netherlands (NL) Chinese Academy of Sciences (CAS) / 中国科学院 CN China (CN) University of Paris 4 - Paris-Sorbonne / Université paris IV Paris-Sorbonne FR France (FR) Sun Yat-Sen University CN China (CN) Washington University US United States (USA) (US) National Aeronautics and Space Administration (NASA) US United States (USA) (US) Université de Paris FR France (FR)

How to cite

APA:

Zhou, M., Grinberg, ., Bu, Q.-C., Santangelo, A., Cangemi, F., Diez, C.M.,... Zhang, S.-N. (2022). The spectral-timing analysis of Cygnus X-1 with Insight-HXMT. Astronomy & Astrophysics, 666. https://dx.doi.org/10.1051/0004-6361/202244240

MLA:

Zhou, M., et al. "The spectral-timing analysis of Cygnus X-1 with Insight-HXMT." Astronomy & Astrophysics 666 (2022).

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