H. Beuther, C. Gieser, V. Aberham, J. M. Winters, R. Neri, A. Ahmadi, R. Kuiper, Th. Henning, H. Linz, T. Möller, V. Elbakyan, L. Moscadelli, D. Semenov, J. Urquhart, P. Klaassen, M. Beltran, Á. Sánchez-Monge, T. Peters, R. Galvan-Madrid, S. Leurini, S. Lumsden, R. E. Pudritz, A. Palau, H. Zinnecker

Context: Although there has been significant progress, the physical properties and potential fragmentation of accretion disks around high-mass protostars remain poorly constrained. Aims: We characterize at high angular resolution one of the most nearby (~700pc) high-mass accretion disk candidates CepA HW2. Methods: Using the new long baseline array configuration (~1700m) of the Northern Extended Millimeter Array (NOEMA), we study CepA HW2 with a resolution of <=0.2'' or <=100au at 1.3mm in dust continuum and spectral line emission. Results: The mm continuum emission resolves the central disk candidate into several sub-structures. Conducting a Toomre Q stability analysis based on CH_3CN and continuum data, and a comparison to 3D radiation hydrodynamic simulations shows that the data are consistent with an almost edge-on disk where the observed sub-structures may represent fragments within the disk. The CO and SiO spectral line data confirm a second bipolar outflow (in addition to the well-known jet) emanating from the central peak position. This indicates that this central peak should host at least a binary if not even a higher order multiple system. The usually assumed dense gas tracer CH_3CN shows also contributions from the outflows which complicates further kinematic analysis of the disk. Conclusions: The high-resolution outflow-disk data of CepA reveal a multiply fragmented disk that drives several outflows. These observations enforce the picture of high-mass star formation where multiplicity and fragmentation can happen on the smallest spatial scales related to the inner accretion disks.