Planned Observations and Science with the BlackCAT CubeSat X-Ray Transient Monitor

The BlackCAT CubeSat will survey the soft X-ray sky, searching for distant gamma-ray bursts (GRBs) and other transient phenomena. We present simulations of BlackCAT observations that illustrate the capabilities of this mission. BlackCAT will identify and localize bursts to sub-arcminute precision, sending rapid alerts to enable follow-up observations and identification of coincident events from multi-messenger networks of observatories. BlackCAT’s sensitivity in the 0.5-20 keV band makes it a particularly valuable detector of high-redshift (z > 5) GRBs, which can serve as powerful probes of the reionization era, when the first stars and galaxies were forming. Optical and near-infrared follow-up observations of afterglows of GRBs identified by BlackCAT will enable measurements of their redshifts and characterization of the environments in which they occurred, in turn allowing measurements of the star formation rate and neutral hydrogen fraction of the intergalactic medium as a function of redshift. We use burst redshift and luminosity functions derived by fits to the Swift Burst Alert Telescope (BAT) GRB sample, and the light curves and spectra of those bursts (redshifted when necessary), to simulate observations of bursts by BlackCAT. From these simulations, we estimate the expected properties of the burst population observed by BlackCAT, including the expected redshift distribution. These simulations will be used to inform the operations, analysis, and follow-up techniques of this mission. We also discuss prospects for observations of X-ray flares and other X-ray transients with BlackCAT, including possible X-ray counterparts to gravitational-wave events, X-ray blazar monitoring, and potential X-ray flare counterparts to neutrino events.