Yoshiaki TANIGUCHI
(The Open University of Japan)
Deep optical imaging with both Hyper Suprime-Cam and Suprime-Cam on the 8.2 m Subaru Telescope reveals a number of outer faint structure around the archetypical Seifert galaxy NGC 1068 (M77). One is the asymmetric outer one-arm structure found at south, other three structures are ultra faint dwarf galaxies surrounding the main body of NGC 1068; hereafter UFDG-SW, UFDG-NE, and UFDG-SE where UFDG = Ultra Faint Dwarf Galaxy, SW = south west, NE = north wast, and SE = south east. Among three UFDGs, UDFG-NE appears to show a very faint bridge-like structure toward the main body of NGC 1068, providing evidence for the physical connection to NGC 1068. The other two UFDGs, UFDG-SW and UFDG-SE appear to emanate from the western edge of the main body of NGC 1068, providing evidence for a tidally induced faint arm. Namely, both UFDG-SW and UFDG-SE can be regarded as so-called tidal dwarf galaxies formed in one tidal arm. All these lines of evidence strongly suggest that NGC 1068 experienced a past minor merger.