Year: 2026
Type: article
Abstract: Neutron stars are among the densest objects in the Universe, and mass measurements are crucial to the understanding of their equations of state. Pulsars in tight binaries can be weighed dynamically, but accurate mass estimates are often hampered by uncertainties in orbital inclinations. In this paper, we report on multiepoch optical monitoring of the pulsar binary, PSR J1048+2339, using the 0.5 m RIFT telescope at Lulin Observatory. Our observations reveal frequent optical flares with eclipses caused by the companion. Using the eclipse duration with archival photometric data and orbital ephemeris in the literature, we constrain the inclination to 78 . ° 0 ± 1 . ° 0 and the pulsar mass to 1.7 9 − 0.08 + 0.09 solar masses. This measurement is among the most precise for any redback system to date, demonstrating a novel way to improve the pulsar mass measures with small-aperture optical telescopes. Furthermore, the optical eclipse duration is significantly shorter than that measured in M/GeV γ -rays, possibly suggesting that a fraction of the eclipsed γ -ray emission originates from the apex of the intrabinary shock. Based on these constraints, we estimate the magnetic field strength of the companion to be 30–170 G. This is consistent with the high field strength implied by the X-ray orbital modulation observed.
Source: The Astrophysical Journal
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Funders: National Science and Technology Council, National Research Foundation, National Natural Science Foundation of China, National Research Foundation of Korea, Ministry of Education, India, National Tsing Hua University, National Science and Technology Council, National Key Research and Development Program of China
OpenAlex ID: W7212038046