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We present results from a deep imaging search for companions around the youngbona-fide and candidate brown dwarfs Cha Ha 1 to 12 in the Cha I dark cloud,performed with HST WFPC2 (R, I, Ha), VLT FORS1 (VRI), and NTT SofI (JHK). Wefind 16 faint companion candidates around five primaries with separationsbetween 1.5" and 7" and magnitudes in R & I from 19 to 25 mag, i.e. up to 8 magfainter than the primaries. While most of these companion candidates areprobably unrelated background objects, there is one promising candidate, namely1.5" SW off the M6-dwarf Cha Ha 5. This candidate is 3.8 to 4.7 mag fainterthan the primary and its colors are consistent with an early- to mid-L spectraltype. Assuming the same distance (140 pc) and absorption (0.47 mag in I) astowards the primary, the companion candidate has log (L(bol)/L(odot) = -3.0 +-0.3. At the age of the primary (1 to 5 Myrs), the faint object would have amass of 3 to 15 Jupiter masses according to Burrows et al. (1997) and Chabrier& Baraffe (2000) models. The probability for this companion candidate to be anunrelated fore- or background object is smaller than 0.7%, its colors aremarginally consistent with a strongly reddened background K giant. One othercompanion candidate has infrared colors consistent with an early T-dwarf. Inaddition, we present indications for Cha Ha 2 being a close (0.2") binary withboth components very close to the sub-stellar limit. Our detection limits aresuch that we should have detected all companions above 1 Jup with separationsabove 2" (320 AU) and all above 5 Jup at 0.35" (50 AU).Comment: A&A 384, 999-1011. appeared 2002, A&A 384, 999-101

HST, VLT, and NTT imaging search for wide companions to bona-fide and candidate brown dwarfs in the Cha I dark cloud