Discovery of a Quasi-Periodic Oscillation in the Ultraluminous X-ray Source IC 342 X-1: XMM-Newton Results

V. K. Agrawal; Anuj Nandi

doi:10.1093/mnras/stu2291

paper

Discovery of a Quasi-Periodic Oscillation in the Ultraluminous X-ray Source IC 342 X-1: XMM-Newton Results

arXiv:1411.4135 · doi:10.1093/mnras/stu2291

Abstract

We report the discovery of a quasi-periodic oscillation (QPO) at 642 mHz in an {\it XMM-Newton} observation of the ultraluminous X-ray source (ULX) IC 342 X-1. The QPO has a centroid at $ν_{QP O} = 642 \pm 20$ mHz, a coherence factor of $Q = 11.6$ , and an amplitude (rms) of 4.1\% with significance of $3.6 σ$ . The energy dependence study shows that the QPO is stronger in the energy range 0.3 - 5.0 keV. A subsequent observation (6 days later) does not show any signature of the QPO in the power density spectrum. The broadband energy spectra (0.3 - 40.0 keV) obtained by quasi-simultaneous observations of {\it XMM-Newton} and {\it NuSTAR} can be well described by an absorbed {\it diskbb} plus {\it cutoffpl} model. The best fitted spectral parameters are power-law index ( $Γ$ ) $\sim$ 1.1, cutoff energy ( $E_{c}$ ) $\sim$ 7.9 keV and disc temperature ( $k T_{in}$ ) $\sim$ 0.33 keV, where the QPO is detected. The unabsorbed bolometric luminosity is $\sim$ 5.34 $\times$ 10 $^{39}$ erg~s $^{- 1}$ . Comparing 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 $\sim 20 - 65 M_{⊙}$ . We discuss the possible implications of our results.

7 pages, 3 figures (2 colour), in press (MNRAS)

Discovery of a Quasi-Periodic Oscillation in the Ultraluminous X-ray Source IC 342 X-1: XMM-Newton Results

Abstract

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