Two Quasi-periodic Oscillations in ESO 113-G010

Abstract

In the narrow-line Seyfert galaxy (NLS1) ESO 113-G010, two quasi-periodic oscillation (QPO) signals are detected in the XMM-Newton data collected in 2005 November. The XMM-Newton telescope has an exposure longer than 100 ks in the energy range of 0.3-10 keV. The data are analyzed using the Lomb-Scargle periodogram (LSP) and the weighted wavelet Z-transform (WWZ) methods. It is found that there are ∼2.24 hour and ∼4.09 hour QPOs in the observation with the confidence levels of 7.3 σ and 4.8 σ, respectively. The two QPO signals have a relationship of approximately 1:2 (1:1.83). The absence of QPO in another observation of the object suggests that it is a transient phenomenon. The relationship between the mass of the ESO 113-G010 central black hole (BH) M_BH and its frequency f_QPO satisfies the known logarithmic linear relation in highly accreting BH systems, from stellar-mass BHs to supermassive BHs. The energy spectrum analysis reveals that the source has a soft X-ray excess below 1 keV.