2023/09/22 by Jiaqi Zhao, Zhao, Jiaqi, C. O. Heinke +2 · 1 voice · 1 citation
Physics and Astronomy · Earth and Planetary Sciences · #Pulsars and Gravitational Waves Research #Geophysics and Gravity Measurements #Astrophysical Phenomena and Observations
paper · pdf · doi:10.48550/arxiv.2309.13189
Millisecond pulsars (MSPs) are faint X-ray sources commonly observed in Galactic globular clusters (GCs). In this work, we investigate 18 MSPs newly found in the GC Omega Centauri (ω Cen) and search for their X-ray counterparts using Chandra observations with a total exposure time of 290.9 ks. We identify confident X-ray counterparts for 11 of the MSPs, with 9 of them newly identified in this work based on their positions, spectral properties, and X-ray colours. The X-ray spectra of 9 MSPs are well described by a neutron star hydrogen atmosphere model, while 2 MSPs are well fitted by a power-law model. The identified MSPs have X-ray luminosities ranging from 1.0×1030 erg s-1 to 1.4×1031 erg s-1. Additionally, for population comparison purposes, we study the X-ray counterpart to MSP E in the GC M71, and find its X-ray spectrum is well described by blackbody-like models with a luminosity of 1.9×1030 erg s-1. We investigate the empirical correlations between X-ray luminosities and minimum companion masses, as well as mass functions, of spider pulsars. Clear correlations are observed, with best-fit functions of log10LX = (1.0±0.1) log10Mc, min + (32.5±0.2) and log10LX = (0.35±0.04) log10\rm MF + (32.71±0.20), respectively, with an intrinsic scatter of log10LX of ∼0.3, where LX is the 0.5-10 keV X-ray luminosity, Mc, min is the minimum companion mass, and MF represents the mass function, in solar masses.