Optical study of TRAPUM pulsars and modelling of the redbacks: PSR J1036−4353 and PSR J1803−6707
Year: 2025
Type: article
Abstract: ABSTRACT The Transients and Pulsars with MeerKAT (TRAPUM) project discovered eight binary millisecond pulsars in its first shallow L-band survey of unidentified Fermi $\gamma$-ray sources using the MeerKAT radio telescope. We conducted follow-up observations using ULTRACAM on the New Technology Telescope at the La Silla Observatory to search for the optical counterpart to the pulsar companions. We found two redback companions, in PSRs J1803–6707 and J1036–4353, and provided upper limits for the other pulsar binaries. We used the Icarus code to fit the redback’s light curves using various irradiation models. The asymmetric double-peak light curves of PSR J1036–4353 are best fit with diffusion and convection models. Comparing the two prescriptions of irradiation and gravity darkening, models with post-irradiation gravity darkening provide superior fits (particularly for lower gravity-darkening exponents), suggesting that the irradiation energy is deposited deep in the stellar photosphere. PSR J1803–6707, on the other hand, displayed variability in the amplitude of its irradiation-dominated light curves over a time-scale of a few months. This effect can be modelled only if the companion’s filling, irradiation temperature, and convection coefficients are allowed to vary over time. Had the star been closer to filling its Roche lobe, like in the cases of the known transitional millisecond pulsars J1023+0038 and J1227–4853, this 4.1 per cent variation in the volume-averaged filling of the star would have caused it to experience a state change to form an active accretion disc.
Institutions: University of Manchester, National Astronomical Research Institute of Thailand, Leibniz University Hannover, Max Planck Institute for Gravitational Physics, Osservatorio Astronomico di Cagliari, National Institute for Astrophysics, Michigan State University, University of Illinois Urbana-Champaign, University College Cork, Heidelberg University, University of Sheffield
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Awards: G2179328939, G2262438693, G3262589058, Constraining Type Ia Supernova Progenitors via their Environments, Fundamental Physics Using Black Widow, Redback and Transitional Pulsar Binaries, G5277459804, Compact Binaries and the Origin of Millisecond Pulsars, Collaborative Research: Charting the Supernova-Gas-Stars Connection via a Major New VLA Survey of the Local Group
OpenAlex ID: W4417182874