| Name: Soma Mandal |
| Affiliation: Government Girls' General Degree College, Kolkata |
| Conference ID: ASI2026_751 |
| Title: AstroSat observations of the ultra-compact X-ray binaries 4U 0614-091 and 1A 1246-588 |
| Abstract Type: Oral |
| Abstract Category: High Energy Phenomena, Fundamental Physics and Astronomy |
| Author(s) and Co-Author(s) with Affiliation: Soma Mandal(Government Girls' General Degree College, Kolkata - 700023, India) |
| Abstract: We present the timing and spectral characteristics of the neutron star low-mass X-ray binaries 4U 0614+091 and 1A 1246-588, with an emphasis on the nature and origin of kilohertz quasi-periodic oscillations (kHz QPOs). For 4U 0614+091, we examine multiple observations spanning different spectral states. During the transition to intermediate states, the electron temperature drops, and the disk moves inward, coinciding with the appearance of a tentative QPO at ~1550 Hz with ~2σ significance. This is accompanied by soft lags and increasing rms, again pointing to heating rate variations as a plausible mechanism. In 1A 1246-588, we detect a narrow upper kHz QPO at 993 ± 2 Hz occurring during a relatively soft spectral state. Soft lags and energy-dependent increasing rms support a scenario where heating rate fluctuations may be responsible for QPO production. |
