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

We present deep observations of the nearby T-type brown dwarf binary$\epsilon$ Indi Bab in radio with the Australia Telescope Compact Array and inX-rays with the Chandra X-ray Observatory. Despite long integration times, thebinary (composed of T1 and T6 dwarfs) was not detected in either wavelengthregime. We reached $3\sigma$ upper limits of $1.23 \times 10^{12}$ and $1.74\times 10^{12}$ erg/s/Hz for the radio luminosity at 4.8 GHz and 8.64 GHz,respectively; in the X-rays, the upper limit in the $0.1-10$ keV band was $3.16\times 10^{23}$ erg/s. We discuss the above results in the framework ofmagnetic activity in ultracool, low-mass dwarfs.Comment: Accepted for publication in the Astrophysical Journal Letter