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We report results from 21-cm intensity maps acquired from the Parkes radiotelescope and cross-correlated with galaxy maps from the 2dF galaxy survey. Thedata span the redshift range $0.057<z<0.098$ and cover approximately 1,300square degrees over two long fields. Cross correlation is detected at asignificance of $5.18\sigma$. The amplitude of the cross-power spectrum is lowrelative to the expected dark matter power spectrum, assuming a neutralhydrogen (HI) bias and mass density equal to measurements from the ALFALFAsurvey. The decrement is pronounced and statistically significant at smallscales. At $k\sim1.5$ $ h \mathrm{Mpc^{-1}}$, the cross power spectrum is morethan a factor of 6 lower than expected, with a significance of $14.8\,\sigma$.This decrement indicates either a lack of clustering of neutral hydrogen (HI),a small correlation coefficient between optical galaxies and HI, or somecombination of the two. Separating 2dF into red and blue galaxies, we find thatred galaxies are much more weakly correlated with HI on $k\sim1.5$ $h\mathrm{Mpc^{-1}}$ scales, suggesting that HI is more associated with bluestar-forming galaxies and tends to avoid red galaxies.

Lack of clustering in low-redshift 21-cm intensity maps cross-correlated with 2dF galaxy densities