X-ray bursts from 4U 1608-52 and the associated low frequency noise

Three type I X-ray bursts and one burst candidate from 4U 1608-52 were observed with RXTE on March 22, 1996. Between the two strongest bursts, an enhanced noise component below 0.01 Hz was observed in the X-ray light curve with RXTE/PCA. It is probably caused by the subsequent time-dependent nuclear burning after the main X-ray burst. This supports the idea that there is a correlation between the Very-Low-Frequency-Noise (VLFN) in Low-Mass X-ray Binaries (LMXBs) and the nuclear burning. Assuming that the time scale of the variations is the time scale for one fire to ignite another, our result suggests the burning front was propagating at less than 3.0×104 cm s−1 on the neutron star surface.