The HEAO1 A2 full sky , 2 - 10 ~ { } keV X-ray map was searched for emission correlated with the plane of the local supercluster of galaxies .
After removing strong point and moderately extended sources ( e.g .
the core of the Virgo cluster ) , there remained a statistically signficant component of “ diffuse ” X-rays in the plane of the supercluster .
Fitting this diffuse component with a simple “ pillbox ” model of the local supercluster implies a volume X-ray emissivity of \varepsilon _ { x } = 3.0 \pm 0.3 \times 10 ^ { 39 } ~ { } ( R _ { SC } / 20 ~ { } Mpc ) ^ { -1 } erg~ { } s ^ { -1 } % Mpc ^ { -3 } where R _ { SC } is the radius of the supercluster and the error is photon counting noise only .
If one considers fluctuations in the X-ray background as an additional component of noise then the significance of the detection is reduced to 2 to 3 \sigma .
This is consistent with fits of the model to data sets obtained by rotating the original data .
The distribution of these rotated fits indicates that the detection is signficant at the 99 \% confidence level .
If the source of the X-ray emission is Bremsstrahlung from a uniformly distributed plasma with temperature T _ { e } then the implied electron number density is N _ { e } = 2.5 \times 10 ^ { -6 } ~ { } ( R _ { SC } / 20 ~ { } Mpc ) ^ { - { 1 \over 2 } } ~ { } ( kT _ { e } / 10 ~ { } keV ) ^ % { - { 1 \over 4 } } ~ { } cm ^ { -3 } .
This value is about an order of magnitude larger than the average baryon number density implied by nucleosynthesis and is consistent with a collapse factor of 10 .
A search for similar structure in the COBE 53 ~ { } GHz microwave background map yielded a marginal detection with an amplitude of \sim - 17 \pm 5 ~ { } \mu K ( statistical error only ) which is consistent with the Sunyaev-Zel ’ dovich ( SZ ) effect expected from 10 ~ { } keV gas .
This latter value is comparable to the amplitude of intrinsic large-scale fluctuations in the microwave background and should be considered to be a 1 \sigma result at best .