Radiation Pressure Instability in the "turn-on" Changing-Look AGN SDSS J1430+2303

Abstract

We present a multi-wavelength study of the changing-look AGN SDSS J1430+2303. The optical flux increased by an order of magnitude over four years, driving a spectral transition from Seyfert 1.9 to 1.2. During the brightened high state, optical, UV, and X-ray light curves exhibited rapid decaying periods with progressively decreasing amplitudes. X-ray spectral analysis reveals a remarkably weak soft excess which declines more steeply than the hard X-rays as the total luminosity decreases. X-ray timing analysis shows a constant break frequency and a hard lag at $\sim 10^{-4}$ Hz during the luminosity decline, indicating a stable disk-corona geometry. Further broad-band spectral energy distribution fitting constrains the black hole mass to the range $M_{\rm BH}=4.7-19.5\times10^7\rm M_\odot$, corresponding to an Eddington ratio to $L/L_{\rm Edd}\sim0.024 - 0.046$, and favors a high spin ($a\gtrsim 0.86$). Consequently, we propose that the observed multi-wavelength decaying periods and damping amplitudes are associated with a shrinking unstable zone, driven by radiation pressure instabilities within the accretion disk.