An XMM-Newton observation of 4U 1755-33 in quiescence:: Evidence of a fossil X-ray jet

We report an XMM-Newton observation of the low-mass X-ray binary and black hole candidate 4U 1755-33. This source had been a bright persistent source for at least 25 yr, but in 1995 it entered an extended quiescent phase. 4U 1755-33 was not detected with an upper limit to the 2-10 keV luminosity of 3.6 x 10(31) d(4kpc)(2) ergs s(-1) (where d(4 kpc) is the distance in units of 4 kpc)-consistent with the luminosity of other black hole candidates in a quiescent state. An unexpected result is the discovery of a narrow 7' long X-ray jetlike feature centered on the position of 4U 1755-33. The spectrum of the jet is similar to that observed from other galactic and extragalactic jets thought to be associated with accreting black holes. The detection of a fossil jet provides additional evidence supporting the black hole candidacy of 4U 1755-33. The spectral properties of three bright serendipitous sources in the field are reported, and it is suggested that these are background active galactic nuclei.