2024/03/14 by Chetana Jain, Jain, Chetana, Rahul Sharma +3 · 1 citation
Engineering · Materials Science · #Boron and Carbon Nanomaterials Research #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Intermetallics and Advanced Alloy Properties #Metal and Thin Film Mechanics #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2403.09595
openalex publication_date 2024/03/14 · openalex created_date 2024/03/16 · openalex updated_date 2026/07/28
We report here results from pulse arrival time delay analysis of the eclipsing high mass X-ray binary pulsar LMC X-4 using observations made with the Rossi X-ray Timing Explorer, XMM-Newton, NuSTAR and AstroSat. Combining the orbital parameters determined from these observations with the historical measurements dating back to 1998, we have extended the Tπ/2 epoch history of LMC X-4 by about 4600 binary orbits spanning about 18 years. We also report mid-eclipse time measurements (Tecl) using data obtained from wide-field X-ray monitors of MAXI-GSC and Swift-BAT. Combining the new Tπ/2 and Tecl estimates with all the previously reported values, we have significantly improved the orbital evolution measurement, which indicates that the orbital period is evolving at a time scale (P\rm orb/P\rm orb ) of about 0.8 Myr. For the first time in an accreting X-ray pulsar system, we confirm the existence of a second derivative of the orbital period, having an evolution time scale (Porb/Porb) of about 55 yr. Detection of a second derivative of the orbital period in LMC X-4 makes its orbital evolution timescale more uncertain, which may also be true for other HMXBs. Independent solutions for the orbital evolution measurement using the mid-eclipse data and the pulse timing data are consistent with each other, and help us put an upper limit of 0.009 on the eccentricity of the binary system.