Schematic of our “fiducial” model for the locations of the northern and southern filaments to the east of the M87 nucleus. The two filaments are indicated with red letters, and we place them on the edge of the radio bubble (see Fig. 11). We also place a red oval near the southern filament which contains the 1 keV plasma detected in our sightline. Due to the expansion of the radio bubble, the northern filament appears red-shifted relative to Earth while the southern filament appears blueshifted. While the impact parameter b between the northern filament and the M87 nucleus (indicated with the black dot) is just 1.9 kpc, in our fiducial model the true distance r between the filament and the nucleus is much higher: r = b/sin θ_fil. In our fiducial model we take θ_fil = θ_jet = 15°, so that r ≈ 7.3 kpc. The pressure in the filament depends on the radius r, as we discuss in Sect. 7.3 and in Eq. (3).