We present the first study of the isotropy of the all-sky distribution of morphological types of galaxies in the Local Universe out to around 200 Mpc using more than 60,000 galaxies from the HyperLeda database .
We use a hemispherical comparison method in which by dividing the sky into two opposite hemispheres , the abundance distribution of the morphological types , T , are compared using the Kolmogorov-Smirnov ( KS ) test and by pointing the axis of symmetry of the hemisphere pairs to different directions in the sky , the KS statistic as a function of sky coordinates is obtained .
For three samples of galaxies within around 100 , 150 , and 200 Mpc , we find a significant hemispherical asymmetry with a vanishingly small chance of occurring in an isotropic distribution .
Astonishingly , regardless of this extreme significance , the observed hemispherical asymmetry for the three distance ranges is aligned with the Celestial Equator at the 97.1 \% - 99.8 \% and with the Ecliptic at the 94.6 \% - 97.6 \% confidence levels , estimated using a Monte Carlo analysis .
Shifting T values randomly within their uncertainties has a negligible effect on this result .
When a magnitude limit of B \leq 15 mag is applied to the above mentioned samples , the galaxies within 100 Mpc show no significant anisotropy after randomization of T .
However , the direction of the asymmetry in the samples within 150 and 200 Mpc and the same magnitude limit is found to be within an angular separation of 32 degrees from ( l,b ) = ( 123.7 , 24.6 ) with 97.2 % and 99.9 % confidence levels , respectively .
This direction is only 2.6 degrees away from the Celestial North Pole .
Unless the Local Universe has a significant anisotropic distribution of galaxy morphologies aligned with the orientation or the orbit of the Earth ( which would be a challenge for the Cosmological Principle ) , our results show that there seems to be a systematic bias in the classification of galaxy morphological types between the data from the Northern and the Southern Equatorial sky .
Further studies are absolutely needed to find out the exact source of this anisotropy .