The accretion rate independence of horizontal branch oscillation in XTE J1701-462

Abstract

We study the temporal and energy spectral properties of the unique neutron star low-mass X-ray binary XTE J1701-462. After assuming the HB/NB vertex as a reference position of accretion rate, the horizontal branch oscillation (HBO) of the HB/NB vertex is roughly 50 Hz. It indicates that the HBO is independent with the accretion rate or the source intensity. The spectral analysis shows $R_{\mathrm{in}}\propto {\dot{M}}_{\mathrm{Disk}}^{2.9\pm 0.09}$ in the HB/NB vertex and $R_{\mathrm{in}}\propto {\dot{M}}_{\mathrm{Disk}}^{1.7\pm 0.06}$ in the NB/FB vertex, which implies that different accretion rate may be produced in the HB/NB vertex and the NB/FB vertex. The Comptonization component could be fitted by constrained broken power law (CBPL) or nthComp. Different with GX 17+2, the frequencies of HBO positively correlate with the inner disk radius, which contradict with the prediction of Lense-Thirring precession model. XTE J1701-462, both in the Cyg-like phase and in the Sco-like phase, follows a positive correlation between the break frequency of broad band noise and the characteristic frequency of HBO, which is called the W-K relation. An anticorrelation between the frequency of HBO and photon energy is observed. Moreover, the rms of HBO increases with photon energy till ~10 keV. We discuss the possible origin of HBO from corona in XTE J1701-462.

45 pages, 18 figures, accepted by ApJ

References in corpus (5)

• RXTE observations of the first transient Z source XTE J1701-462: shedding new light on mass accretion in luminous neutron star LMXBs
• High-frequency Quasi-Periodic Oscillations from GRS 1915+105 in its C state
• An explanation of the Z-track sources
• Type I X-ray Bursts from the Neutron-star Transient XTE J1701-462
• Correlations between X-ray Spectral and Timing Characteristics in Cyg X-2

Cited by in corpus (3)

• Correlations in Horizontal Branch Oscillations and Break Components in XTE J1701-462 and GX 17+2
• Correlated spectro-polarimetric study along the Z track in XTE J1701-462 puts constraints on its coronal geometry
• AstroSat View of Transient Low-mass X-ray Binary XTE J1701-462: Spectral and Temporal Evolution along the Z-track