Searches for Shapiro delay in seven binary pulsars using the MeerKAT telescope

Abstract

Precision timing of millisecond pulsars in binary systems enables observers to detect the relativistic Shapiro delay induced by space time curvature. When favourably aligned, this enables constraints to be placed on the component masses and system orientation. Here we present the results of timing campaigns on seven binary millisecond pulsars observed with the 64-antenna MeerKAT radio telescope that show evidence of Shapiro delay: PSRs J0101−6422, J1101−6424, J1125−6014, J1514−4946, J1614−2230, J1732−5049, and J1909−3744. Evidence for Shapiro delay was found in all of the systems, and for three the orientations and data quality enabled strong constraints on their orbital inclinations and component masses. For PSRs J1125−6014, J1614−2230 and J1909−3744, we determined pulsar masses to be Mp = 1.68 ± 0.17 M⊙, 1.94 ± 0.03 M⊙ and 1.45 ± 0.03 M⊙, and companion masses to be Mc = 0.33 ± 0.02 M⊙, 0.495 ± 0.005 M⊙ and 0.205 ± 0.003 M⊙, respectively. This provides the first independent confirmation of PSR J1614−2230’s mass, one of the highest known. The Shapiro delays measured for PSRs J0101−6422, J1101−6424, J1514−4946, and J1732−5049 were only weak, and could not provide interesting component mass limits. Despite a large number of millisecond pulsars being routinely timed, relatively few have accurate masses via Shapiro delays. We use simulations to show that this is expected, and provide a formula for observers to assess how accurately a pulsar mass can be determined. We also discuss the observed correlation between pulsar companion masses and spin period, and the anti-correlation between recycled pulsar mass and their companion masses.

The Third Fermi Large Area Telescope Catalog of Gamma-Ray Pulsars

“…Furthermore, R NS = 10 km is an outdated convention, andµ E M R NS NS 2  is ≈2times larger than what we use, reducing all η values. The neutron star mass values M NS in our sample probably have variance <20% (see, for example, Figure5inShamohammadi et al 2023), contributing imperceptibly to the luminosity dispersion.The lower diagonal shows the "heuristic" gamma-ray pulsar luminosity, electron-positron cascades occur in an acceleration region with a self-governing size that produces a gamma-ray efficiency ò γ ∝ 1/V(Arons 1996). Recent particlein-cell simulations of pulsar magnetospheres also support the idea of a critical pair production rate below which pulsar magnetospheres become "dead" (e.g.,Kalapotharakos et al 2018;Philippov & Spitkovsky 2018;Chen et al 2020).…”

Radio timing constraints on the mass of the binary pulsar PSR J1528−3146

“…In this respect, the current mass measurement of the WD companion to PSR J1528−3146 is already important because it confirms the existence of this third clump, and highlights the general pattern. There are very few WD masses outside these ranges: in two cases, they orbit pulsars that are not recycled, and in very few other cases (e.g., PSR J1614−2230, Crawford et al 2006;Arzoumanian et al 2018;Shamohammadi et al 2023), the system is thought to have evolved through case A Roche lobe overflow (Tauris et al 2011), which is a likely explanation for their very short spin periods.…”