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Discovery of a quasi-periodic oscillation in the ultraluminous X-ray source IC 342 X-1: XMM-Newton results

Agrawal, V. K. and Nandi, A. (2014) Discovery of a quasi-periodic oscillation in the ultraluminous X-ray source IC 342 X-1: XMM-Newton results. Monthly Notices of the Royal Astronomical Society, 446 (4). pp. 3926-3931. ISSN 0035-8711. doi:10.1093/mnras/stu2291.

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We report the discovery of a quasi-periodic oscillation (QPO) at 642 mHz in an XMM–Newton observation of the ultraluminous X-ray source (ULX) IC 342 X-1. The QPO has a centroid at νQPO = 642 ± 20 mHz, a coherence factor Q = 11.6 and an amplitude (rms) of 4.1 per cent with significance of 3.6σ. The energy dependence study shows that the QPO is stronger in the energy range 0.3–5.0 keV. A subsequent observation (6 d later) does not show any signature of the QPO in the power-density spectrum. The broad-band energy spectra (0.3–40.0 keV) obtained by quasi-simultaneous observations of XMM–Newton and NuSTAR can be described well by an absorbed diskbb plus cutoffpl model. The best-fitting spectral parameters are power-law index (Γ) ∼ 1.1, cut-off energy (Ec) ∼ 7.9 keV and disc temperature (kT_in) ∼ 0.33 keV where the QPO is detected. The unabsorbed bolometric luminosity is ∼5.34 × 1039 erg s−1. Comparing this with the well-known X-ray binary GRS 1915+105, our results are consistent with the mass of the compact object in IC 342 X-1 being in the range ∼20–65 M⊙. We discuss the possible implications of our results.

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Additional Information:© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 October 29. Received 2014 October 29; in original form 2013 December 27. The authors thank the anonymous referee for a careful reading of the article and constructive criticism, along with useful suggestions for improvement of the manuscript. We also thank Drs Girish and Das for careful reading and comments on the manuscript. This research has made use of data and/or software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC). We thank Dr Anil Agarwal, GD, SAG, Mr Vasantha E DD, CDA and Dr S. K. Shivakumar, Director, ISAC, for encouragement and continuous support to carry out this research.
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Record Number:CaltechAUTHORS:20160128-132152642
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ID Code:64050
Deposited By: Joy Painter
Deposited On:28 Jan 2016 22:45
Last Modified:10 Nov 2021 23:25

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