Left: (a) Variation in PFs in RX J0440.9+4431 during the 2022–2023 giant outburst in the energy ranges of 1–10 keV, 10–30 keV, and 30–150 keV obtained, respectively, from the LE, ME, and HE light curves. Right: (b) Variation in PF is shown with the outburst source luminosity in 1–120 keV in RX J0440.9+4431 during the 2022–2023 giant outburst in the energy ranges of 1–10 keV, 10–30 keV and 30–150 keV obtained, respectively, from the LE, ME and HE light curves. Table A.1 in the appendix shows the values of these PF estimates and the respective epochs of the giant outburst. The color bar represents the 1–120 keV source luminosity in units of 10³⁷ erg s⁻¹. The two vertical dashed lines at L_x ∼ 1 × 10³⁷ erg s⁻¹ and L_x ∼ 2.2 × 10³⁷ erg s⁻¹ represent the turnover points in the variation of PF with outburst luminosity.