2025A&A...704A.123N

Aims. In this work we investigate whether the 2-min bursts every 44 min from ASKAP J1832-0911 can be explained by Lense-Thirring precession of an intermediate-mass black hole (IMBH) accretion disk launching a jet as an alternative to magnetar or white dwarf models.
Methods. We derived the Lense-Thirring period $ P_\mathrm{{LT}}=\frac{\pi G M}{a c^3}r^3 $ and solved P_LT = 44 min to obtain the black hole mass, M, and dimensionless radius, r = R/R_g. We estimated the equipartition field, B, at r while assuming an advection dominated accretion flow or a magnetically arrested disk accretion model; we computed the Blandford-Znajek power, P_BZ,; and we compared the resulting jet luminosity to the observed radio and X-ray fluxes at D ≈ 4.5 kpc. We also describe a coherent emission model based on a merging plasmoid close to the black hole.
Results. For a ∼ 0.3 - 0.9, an IMBH with M ∼ 10³ - 10⁵ M_⊙ yields r ∼ 10 - 40 R_g and P_LT = 44 min. Equipartition gives B ∼ 10⁵ G at r, leading to P_BZ ∼ 10^35 - 39^ erg s^–1. With a radiative efficiency of ϵ_j ∼ 10^–2 - 10^–1, the predicted L_jet ∼ 10^34 - 36^ erg s^–1 matches the observed F_X ∼ 10^–12 erg cm^–2 s^–1 and radio flux. The variability at ≲100 s could be clear evidence supporting this model.
Conclusions. The IMBH precessing-jet model simultaneously explains the periodicity, energetics, and duty cycle of ASKAP J1832-0911. Only high time resolution X-ray timing (in order to exclude ∼s pulsations) and multi-frequency radio polarimetry (to confirm a flat, low-polarization spectrum) can definitively distinguish the IMBH model from magnetar or white dwarf scenarios.