«Before we had this capability, we could not detect the numerous faint sources that produce much of the background emission,» he added. (sciencedaily.com)
«Detecting pulsations in faint sources is challenging, because the X-ray data are not always collected with sufficiently high time - resolution to make the measurement,» he says. (sciencedaily.com)
He adds: «Our results highlight how hard it is to study the small faint sources in the early universe. (sciencedaily.com)