X-ray study of MSPs in globular clusters

We compile previous X-ray studies of GC MSPs, and add new analyses of six MSPs (PSRs J1326-4728A, J1326-4728B, J1518+0204C, J1717+4308A, J1737-0314A, and J1807-2459A) discovered in five GCs. Their X-ray spectra are well described by a single blackbody model, a single power-law model, or a combination of them, with X-ray luminosities ranging from 1.9

• 10^30^ to 8.3
• 10^31^ erg/s. We find that most detected X-ray MSPs have luminosities between ~10^30^ and 3
• 10^31^ erg/s. Redback pulsars are a relatively bright MSP population with X-ray luminosities of ~2
• 10^31^ - 3
• 10^32^ erg/s. Black widows show a bimodal distribution in X-ray luminosities, with eclipsing black widows between ~7
• 10^30^ and 2
• 10^31^ erg/s, while the two confirmed non-eclipsing black widows are much fainter, with L_X_ of 1.5-3
• 10^30^ erg/s, suggesting an intrinsic difference in the populations. We estimate the total number of MSPs in 36 GCs by considering the correlation between the number of MSPs and stellar encounter rate in GCs, and suggest that between 600 and 1500 MSPs exist in these 36 GCs. Finally, we estimate the number of X-ray-detectable MSPs in the Galactic bulge, finding that 1-86 MSPs with L_X_ > 10^33^ erg/s, and 20-900 MSPs with L_X_ > 10^32^ erg/s should be detectable there.