Work

A new likely pulsar binary in 47 Tucanae from continuum searches

Year: 2026

Type: article

Abstract: We present evidence that the X-ray source 47 Tuc W41, long considered to be an X-ray source powered by coronal activity, is actually a redback pulsar binary. The source continually shows L Subscript normal upper X Baseline equals 3 times 10 Superscript 31 X = 3 × 10 31 $_{\rm X} = 3 \times 10^{31}$ erg s Superscript negative 1 − 1 $^{-1}$ (0.5–10 keV), which is well in excess of the coronal saturation limit for active binaries in quiescence, but is consistent with the intrabinary shock observed in redback pulsars, as is its photon index of normal upper Gamma equals 1.4 plus or minus 0.1 Γ = 1.4 ± 0.1 $\Gamma = 1.4\pm0.1$ . In addition, using deep data from the Australia Telescope Compact Array, we show that W41 is a faint ( 9.8 plus or minus 1.4 mu 9.8 ± 1.4 μ $9.8\pm1.4\,\unicode{x03BC}$ Jy at 5.5 GHz) steep spectrum ( alpha equals negative 1.8 plus or minus 0.4 α = − 1.8 ± 0.4 $\alpha = -1.8\pm0.4$ ) radio continuum source, as expected for a pulsar. Light curve modelling of Hubble Space Telescope photometry shows evidence for ellipsoidal modulation with mild irradiation of a tilde 0.5 ∼ 0.5 $\sim 0.5$ – 0.55 0.55 $0.55$ M Subscript circled dot <

Source: Publications of the Astronomical Society of Australia

DOI: 10.1017/pasa.2026.10239