A census of X-ray millisecond pulsars in globular clusters

ABSTRACT We present a comprehensive census of X-ray millisecond pulsars (MSPs) in 29 Galactic globular clusters (GCs), including 68 MSPs with confirmed luminosities and 107 upper limits. compile previous studies GC MSPs, add new analyses six (PSRs J1326–4728A, J1326–4728B, J1518+0204C, J1717+4308A, J1737–0314A, J1807–2459A) discovered five GCs. Their spectra are well described by single blackbody model, power-law or combination them, ranging from 1.9 × 1030to 8.3 1031 erg s−1. find that most detected have between ∼1030 3 Redback relatively bright MSP population ∼2 1031–3 1032 Black widows show bimodal distribution luminosities, eclipsing black ∼7 1030 2 s−1, while the two non-eclipsing much fainter, LX 1.5–3 suggesting an intrinsic difference populations. estimate total number 36 GCs considering correlation stellar encounter rate GCs, suggest 600 1500 exist these Finally, we X-ray-detectable bulge, finding 1–86 > 1033 20–900 s−1 should be detectable there.