Discovery of a 459 Hz Burst Oscillation in XTE J1810?189 with NICER
We present a detailed temporal study of a type I X-ray burst from the neutron star low-mass X-ray binary (NS-LMXB) XTE J1810?189, observed on 2023 April 27 using the Neutron Star Interior Composition Explorer. The burst exhibited a rapid rise time of 2.55 s, followed by an exponential decay lasting for 7.5 s, with a total duration of ?13 s. Type I X-ray bursts are driven by thermonuclear burning on the surface of a neutron star in an NS-LMXB. As these bursts originate from the stellar surface they can exhibit highly coherent signals known as burst oscillations, which serve as probes of the neutron stars spin frequency. We report the detection of a burst oscillation signal at ?459 Hz at the cooling tail of the burst. The oscillation showed a strong Leahy-normalized power of PL = 35.95 at 458.92 Hz, corresponding to a single-trial significance of 5.53? and a multiple-trial corrected significance of 3.14?. The folded pulse profile in the 0.212 keV band is well described by a constant plus sinusoid with a fractional rms amplitude of 14.63%. These results suggest that the burst oscillation frequency of XTE J1810-189 directly reflects on the neutron stars spin, measured here to be ?2.18 ms, placing it among the rapidly rotating NS-LMXBs. This burst oscillation signal at the cooling tail of the burst can be interpreted through surface mode model or the asymmetric cooling wake model. 2025. The Author(s). Published by the American Astronomical Society.
Varun, M.; Thomas, Neal Titus; Gudennavar, S.B.; Bubbly, S.G.
Astrophysical Journal;Volume;995;Issue;2;Article No.;153;
All Open Access; Gold Open Access; Green Open Access
https://doi.org/10.3847/1538-4357/ae21d3 https://www.scopus.com/pages/publications/105034005356?origin=resultslist
Varun M., Department of Physics and Electronics, CHRIST University, Karnataka, Bangalore, 560029, India; Thomas N.T., Department of Physics and Electronics, CHRIST University, Karnataka, Bangalore, 560029, India; Gudennavar S.B., Department of Physics and Electronics, CHRIST University, Karnataka, Bangalore, 560029, India; Bubbly S.G., Department of Physics and Electronics, CHRIST University, Karnataka, Bangalore, 560029, India