The Local Hole: a galaxy under-density covering 90% of sky to ~200 Mpc

Understand

We investigate the `Local Hole', an anomalous under-density in the local galaxy environment, by extending our previous galaxy $K-$band number-redshift and number-magnitude counts to $\approx 90\%$ of the sky.

• Our redshift samples are taken from the 2MASS Redshift Survey (2MRS) and the 2M++ catalogues, limited to $K<11.5$.
• We find that both surveys are in good agreement, showing an $\approx 21-22\%$ under-density at $z<0.075$ when compared to our homogeneous counts model that assumes the same luminosity function and other parameters as in our earlier papers.
• Using the Two Micron All Sky Survey (2MASS) for $n(K)$ galaxy counts, we measure an under-density relative to this model of $20\pm 2 \%$ at $K<11.5$, which is consistent in both form and scale with the observed $n(z)$ under-density.