A Deep Look at the T-Type Brown Dwarf Binary ε Indi Bab with Chandra and the Australia Telescope Compact Array

Abstract

We present deep observations of the nearby T-type brown dwarf binary Indi Bab in radio with the Australia Telescope Compact Array and in X-rays with the Chandra X-Ray Observatory. Despite long integration times, the binary (composed of T1 and T6 dwarfs) was not detected in either wavelength regime. We reached 3 σ upper limits of 1.23 × 1012 and 1.74 × 1012 ergs s-1 Hz-1 for the radio luminosity at 4.8 and 8.64 GHz, respectively; in X-rays, the upper limit in the 0.1-10 keV band was 3.16 × 1023 ergs s-1. We discuss the above results in the framework of magnetic activity in ultracool, low-mass dwarfs.