A New, Faint Population of X-ray Transients

We report on the detection of a remarkable new fast high-energy transient found in the Chandra Deep Field-South, robustly associated with a faint (mR = 27.5 mag, zph ∼ 2.2) host in the CANDELS survey. The X-ray event is comprised of 115$^{+12}_{-11}$ net 0.3–7.0 keV counts, with a light curve characterized by an ≈100 s rise time, a peak 0.3–10 keV flux of ≈5 × 10−12 erg s−1 cm−2 and a power-law de...