SOURCE-INTRINSIC NEAR-INFRARED PROPERTIES OF SGR A*: TOTAL INTENSITY MEASUREMENTS

Abstract

We present a comprehensive data description for Ks-band measurements of Sgr\nA*. We characterize the statistical properties of the variability of Sgr A* in\nthe near-infrared, which we find to be consistent with a single-state process\nforming a power-law distribution of the flux density. We discover a linear\nrms-flux relation for the flux-density range up to 12 mJy on a timescale of 24\nminutes. This and the power-law flux density distribution implies a\nphenomenological, formally non-linear statistical variability model with which\nwe can simulate the observed variability and extrapolate its behavior to higher\nflux levels and longer timescales. We present reasons why data with our cadence\ncannot be used to decide on the question whether the power spectral density of\nthe underlying random process shows more structure at timescales between 25 min\nand 100 min compared to what is expected from a red noise random process.\n