As cosmic structures form , matter density fluctuations collapse gravitationally and baryonic matter is shock-heated and thermalized .
We therefore expect a connection between the mean gravitational potential energy density of collapsed halos , \Omega _ { W } ^ { halo } , and the mean thermal energy density of baryons , \Omega _ { th } .
These quantities can be obtained using two fundamentally different estimates : we compute \Omega _ { W } ^ { halo } using the theoretical framework of the halo model which is driven by dark matter statistics , and measure \Omega _ { th } using the Sunyaev-Zeldovich ( SZ ) effect which probes the mean thermal pressure of baryons .
First , we derive that , at the present time , about 90 % of \Omega _ { W } ^ { halo } originates from massive halos with M > 10 ^ { 13 } M _ { \odot } .
Then , using our measurements of the SZ background , we find that \Omega _ { th } accounts for about 80 % of the kinetic energy of the baryons available for pressure in halos at z \lesssim 0.5 .
This constrains the amount of non-thermal pressure , e.g. , due to bulk and turbulent gas motion sourced by mass accretion , to be about \Omega _ { non - th } \simeq 0.4 \times 10 ^ { -8 } at z = 0 .