We present a study of the spatial and redshift distributions of Sloan Digital Sky Survey ( SDSS ) galaxies toward the position of CrB-H , a very deep and extended decrement in the Cosmic Microwave Background ( CMB ) , located within the Corona Borealis supercluster ( CrB-SC ) .
It was found in a survey with the Very Small Array ( VSA ) interferometer at 33 GHz , with a peak negative brightness temperature of -230 ~ { } \mu K , and deviates 4.4 \sigma from the Gaussian CMB ( Génova-Santos et al . ) .
Observations with the Millimeter and Infrared Testa Grigia Observatory ( MITO ) suggested that 25 ^ { +21 } _ { -18 } \% of this decrement may be caused by the thermal Sunyaev-Zel ’ dovich ( tSZ ) effect ( Battistelli et al . ) .
Here we investigate whether the galaxy distribution could be tracing either a previously unnoticed galaxy cluster or a Warm/Hot Intergalactic Medium ( WHIM ) filament that could build up this tSZ effect .

We find that the projected density of galaxies outside Abell clusters and with redshifts 0.05 < z < 0.12 at the position of CrB-H is the highest in the area encompassed by the CrB-SC .
Most of these galaxies are located around redshifts z = 0.07 and z = 0.11 , but no clear connection in the form of a filamentary structure is appreciable in between .
While the galaxy distribution at z = 0.07 is sparse , we find evidence at z = 0.11 of a galaxy group or a low-mass galaxy cluster .
We estimate that this structure could produce a tSZ effect of \approx - 18 ~ { } \mu K. The remaining VSA signal of \approx - 212 ~ { } \mu K is still a significant 4.1 \sigma deviation from the Gaussian CMB .
However , the MITO error bar allows for a larger tSZ effect , which could be produced by galaxy clusters or superclusters beyond the sensitivity of the SDSS .
Contributions from other possible secondary anisotropies associated with these structures are also discussed .

Subject headings : galaxies : clusters : individual galaxies : distances and redshifts large-scale structure of universe surveys