A 0.03 Hz Radio Quasi-periodic Oscillation During the 2025 Flare of GRS 1915+105

Abstract

Our weekly-cadence radio monitoring campaign captured a bright flare in 2025 from the microquasar GRS 1915+105, observed simultaneously in the S- and X-bands (2.25 GHz and 8.42 GHz) with a short single baseline of two radio telescopes in Shanghai. Through high time resolution analysis, we detected a significant and short-lived quasi-periodic oscillation (QPO) at $\sim$0.03 Hz and its harmonic ($\sim$0.06 Hz) in both radio bands of two consecutive observations on MJD 60765 ($>5.9 σ$) and MJD 60772 (2.8$σ$). Crucially, the QPO frequency is identical in both radio bands and matches oscillations detected in previous years. The recurrence and wavelength independence of the QPO frequency suggest an intrinsic characteristic timescale of the accretion-jet system.