Dipolar modulation in number counts of WISE-2MASS sources

Understand

We test the statistical isotropy of the universe by analyzing the distribution of WISE extragalactic sources that were also observed by 2MASS.

• We pay particular attention to color cuts and foreground marginalization in order to cull a uniform sample of extragalactic objects and avoid stars.
• We detect a dipole gradient in the number-counts with an amplitude of $\sim$0.05, somewhat larger than expectations based on local structures corresponding to the depth and (independently measured) bias of our WISE-2MASS sources.
• The direction of the dipole, $(l,b)\simeq (310\,^{\circ}, -15\,^{\circ})$, is in reasonably good agreement with that found previously in the (shallower) 2MASS Extended Source Catalog alone.