One-dimensional profiles of the SZ signal from stacked galaxy pairs. Panel a: mean radial SZ profile extracted along the vertical direction in the left-hand panel of Fig. 1. Panel b: mean horizontal profile with a thickness of 6 h⁻¹ Mpc extracted from the left-hand panel of Fig. 1; the residual of the radial profile (panel c) and the horizontal profile (panel d) after subtracting the contribution from the two haloes. Error bars in panels a and b represent simple estimates of the errors in the mean profile, while in panels c and d the error bars are obtained from a detailed jackknife analysis. The blue dashed lines and the green dash-dotted line indicate the modelled primary and secondary halo contributions respectively. The pink solid lines show the combined modelled contribution from the two haloes. The residual in panel c is consistent with zero, indicating the success of our modelling. The detected filament lies interior to the halo centres (dotted lines), shown by the offset between the solid pink line and the black data points in panel b, and by the residuals in panel d.