A temporal scale to track the spectral transitions in low-mass X-ray binaries

Sonbas, E. and Mohamed, K. and Dhuga, K. S. and Göğüş, Ersin (2022) A temporal scale to track the spectral transitions in low-mass X-ray binaries. Monthly Notices of the Royal Astronomical Society, 511 (2). pp. 2535-2543. ISSN 0035-8711 (Print) 1365-2966 (Online)

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The results of a temporal analysis of observations for a sample of nine low-mass X-ray binaries (LMXBs) are presented. Of these sources, five host a neutron star (NS) primary (4U1608-52, Aql X-1, 4U1705-44, GX17+2-, and Cyg X-2), and four host a black hole (BH) (GX339-4, XTE J1859+226, H1743-322, and MAXI J1659-152). The NS group includes three Atolls and two Z-type sources. We utilized archival Proportional Counter Array (PCA)/RXTE data to construct high-resolution light-curves. A wavelet transform of the light curves is deployed to extract a minimal time-scale (MTS) associated with the spectral state of the sources. The MTS, together with the fractional root-mean-square (rms) and hardness ratios, is used to construct RMS-MTS and hardness-MTS diagrams that enable a direct comparison of the evolution of spectral transitions in the target sources. Observations with high fractional rms and high hardness cluster in a broad region occupied jointly by BH and NS sources. For low fractional rms observations, the Atolls exhibit large MTS whereas Z-type sources exhibit small MTS. This new feature raises the possibility of discriminating between these two types of sources. Moreover, in the hardness-MTS plane, BH sources are the sole occupiers of the low-hardness and small-MTS domain thus potentially signalling a unique property for distinguishing BH and NS hosts in LMXBs.
Item Type: Article
Uncontrolled Keywords: Methods: data analysis; Stars: black holes; X-rays: binaries
Divisions: Faculty of Engineering and Natural Sciences
Depositing User: Ersin Göğüş
Date Deposited: 24 Aug 2022 23:05
Last Modified: 24 Aug 2022 23:05
URI: https://research.sabanciuniv.edu/id/eprint/44037

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