We present a blind search for doublet intergalactic metal absorption with a method dubbed ‘ agnostic stacking ’ .
Using a forward-modelling framework we combine this with direct detections in the literature to measure the overall metal population .
We apply this novel approach to the search for Ne viii absorption in a set of 26 high-quality COS spectra .
We probe to an unprecedented low limit of log N > 12.3 at 0.47 \leq z \leq 1.34 over a pathlength \Delta z = 7.36 .
This method selects apparent absorption without requiring knowledge of its source .
Stacking this mixed population dilutes doublet features in composite spectra in a deterministic manner , allowing us to measure the proportion corresponding to Ne viii absorption .
We stack potential Ne viii absorption in two regimes : absorption too weak to be significant in direct line studies ( 12.3 < log N < 13.7 ) , and strong absorbers ( log N > 13.7 ) .
We do not detect Ne viii absorption in either regime .
Combining our measurements with direct detections , we find that the Ne viii population is reproduced with a power law column density distribution function with slope \beta = -1.86 \substack { +0.18 \ -0.26 } and normalisation log f _ { 13.7 } = -13.99 \substack { +0.20 \ -0.23 } , leading to an incidence rate of strong Ne viii absorbers dn / dz = 1.38 \substack { +0.97 \ -0.82 } .
We infer a cosmic mass density for Ne viii gas with 12.3 < log N < 15.0 of \Omega _ { \textrm { \mbox { Ne { \sc viii } } } } = 2.2 \substack { +1.6 \ _ { - } 1.2 } \times 10 ^ { -8 } , a value significantly lower that than predicted by recent simulations .
We translate this density into an estimate of the baryon density \Omega _ { b } \approx 1.8 \times 10 ^ { -3 } , constituting 4 % of the total baryonic mass .