Year: 2025
Type: article
Abstract: ABSTRACT X-ray emission is generally believed to be one of the major heating sources for the optical modulation in redback pulsar binaries as we have seen similar phenomena in many low-mass X-ray binaries (LMXBs). While, e.g. MeV/GeV $\gamma$-rays from the neutron stars are also possible heating sources, X-ray observations are currently much more sensitive, and therefore, joint optical–X-ray data are observationally unique on the irradiation mechanism investigation. Using 18 X-ray/B-band simultaneous XMM–Newton observations (717 ks in total) of the redback system PSR J1023+0038 taken during the LMXB state, we find a general trend that the amplitude of the B-band orbital modulation was lower when the observed X-ray flux was higher. Depending on the analysis method adopted, the statistical significance of the anticorrelation can be from 1.7$\sigma$ to 3.1$\sigma$. We also extended the analysis to the GeV $\gamma$-ray band using the Fermi-LAT data, but the result is insignificant to claim any relations. Moreover, another X-ray/optical correlation regarding the low modes of the system was found in some of the XMM–Newton observations, and the astrophysical reason behind is currently unclear yet. These anticorrelations likely suggest that the irradiation is generally stronger when the X-ray flux is in a fainter state, indicating that there is a more dominant irradiation source than the X-ray emission.
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Funders: National Science and Technology Council, U.S. Department of Energy, National Aeronautics and Space Administration, National Research Foundation, Ministry of Education, Culture, Sports, Science and Technology, National Natural Science Foundation of China, National Research Foundation of Korea, Agenzia Spaziale Italiana, Vetenskapsrådet, Ministry of Education, India, Centre National de la Recherche Scientifique, Istituto Nazionale di Astrofisica, High Energy Accelerator Research Organization, Istituto Nazionale di Fisica Nucleare, National Science and Technology Council, Japan Aerospace Exploration Agency, National Key Research and Development Program of China, Institut National de Physique Nucléaire et de Physique des Particules
Awards: G1141912172, Mapping the Extreme Universe with Multi-Messenger Observations( III ), G1865003800, G2371548206, G2454321696, G2680507221, G303061748, G389958192, G4188389631, G4473368111, G4505693567, How Neutron Stars Are Recycled? a Deep Exploration of the Sub- Luminous State of Spider-Stars( I ), G5438923238, G5570207115, G5573132103, G6396639593, G8092632321, G919133822, G969889393
OpenAlex ID: W4415105774