Speaker
Description
Accreting stellar-mass black holes are known to populate two distinct tracks in the radio:X-ray luminosity plane, commonly referred to as the radio-loud and radio-quiet branches. Despite nearly four decades of observational and theoretical efforts, the physical origin of this dichotomy remains poorly understood. We have carried out a systematic study of the X-ray timing properties of a large sample of black hole low-mass X-ray binaries using archival NICER observations. Our analysis reveals that radio-loud and radio-quiet systems exhibit markedly different power spectral density (PSD). In particular, radio-loud sources tend to display 'softer' power spectra, with a larger fraction of their variability power concentrated at low frequencies. These results suggest that the radio-loud/radio-quiet dichotomy may be linked not only to the average properties of the accretion flow but also to its variability structure. We discuss the implications of this finding for the accretion–ejection connection and for understanding the physical mechanisms that regulate jet production in accreting black holes.