SIMBAD references

The Swift/XRT detected the X-ray afterglow of long burst GRB 220117A, which began to rebrighten 300 s after triggering and followed a single power-law decay segment after thousands of seconds of the orbital observation gap. This segment is different from the shallow decay segment (plateau) and flare, and may belong to a giant X-ray bump. We investigated this segment by the fall-back accretion model and found that the model can interpret this segment with reasonable parameter values. Within this physical model scenario, the fall-back accretion rate reaches a peak value ∼1.70 × 10^–5M_⊙ s^–1 around 300 s in the central engine frame, which is compatible with the late mass supply rate of some low-metallicity massive progenitor stars. The initial black hole (BH) spin is ${a}_{0}={0.64}_{-0.26}^{+0.24}$ and implies that this re-brightening signature requires a larger BH spin. The total accretion mass during the fall-back process is M_acc = (3.09 ± 0.02) × 10^–2M_⊙. The jet energy from the fall-back accretion is (9.77 ± 0.65) × 10⁵² erg, with a ratio of 0.066 to the isotropic-equivalent radiation energies of the GRB prompt phase in the 1-10⁴ keV band. The fall-back radius r_p corresponding to the peak time of fall-back t_p is (3.16 ± 0.05) × 10¹⁰ cm, which is consistent with the typical radius of Wolf-Rayet stars. In summary, our results provide additional support for the origin of the long burst from the core collapse of Wolf-Rayet stars, and its late central engine activity is likely due to the fall-back accretion process.