Observing the Long‐Term Activity of Cosmic Sources by a Combination of X‐Ray Monitors

ABSTRACT I demonstrate that combining observations (in 1‐day bins) from various X‐ray monitors with different energy bands onboard different satellites is beneficial for investigating the features of the long‐term activity of X‐ray binaries. Combining the data from MAXI/ ISS and BAT/ Swift and comparing the profiles of the light curves enable the investigation of long‐term activity at energies between 2 and 50 keV. One‐day binning is sufficient for resolving the typical features of the activity. Combinations of the data from these monitors reveal significant structural changes in the emitting regions that occur during these features. This combination of X‐ray monitors has the scientific potential to investigate the role of various physical mechanisms on long timescales. I show the results of this approach on the activity of the soft X‐ray transient 4U 1608–52 and a persistent source 4U 1705–440 with accreting neutron stars. The series of X‐ray monitors is necessary to obtain long‐term light curves (e.g., outbursts, state transitions) in a broad energy range. Large satellites are required to obtain detailed observations (spectra, rapid variations) across a broad energy range and in specific and essential phases of activity detected by the monitors.