The Local Group is a small galaxy cluster with the membership of 62 nearby galaxies including the Milky Way and M31 .
Although the Local Group has yet to be virialized , it interacts with the surrounding matter as one gravitationally bound system .
To understand the formation and evolution of the Local Group as well as its member galaxies , it is important to reconstruct the gravitational potential field from the surrounding matter distribution in the local cosmic web .
By measuring the anisotropy in the spatial distribution of the Local Group galaxies , which is assumed to be induced by the local gravitational tidal field , we resolve the three dimensional structure of the gravitational potential in the vicinity of the Milky Way smoothed on the Local Group mass scale .
Our results show that ( i ) the minor principal axis of the Local Group tidal field is in the equatorial direction of \alpha _ { p } = 15 ^ { h } 00 ^ { m } and \delta _ { p } = 20 ^ { d } ; ( ii ) it has a prolate shape with axial ratio of 0.5 \pm 0.13 ; ( iii ) the global tides in the Local Group is quite strong , which may provide a partial explanation for the low abundance of dwarf galaxies in the Local Group .