Unexpected clustering pattern in dwarf galaxies challenges formation models.

The galaxy correlation function serves as a fundamental tool for studying cosmology, galaxy formation and the nature of dark matter. It is well established that more massive, redder and more compact galaxies tend to have stronger clustering in space. These results can be understood in terms of galaxy formation in cold dark matter (CDM) halos of different mass and assembly history.

Probing Primordial Chirality with Galaxy Spins.

Chiral symmetry is maximally violated in weak interactions [1], and such microscopic asymmetries in the early Universe might leave observable imprints on astrophysical scales without violating the cosmological principle. In this Letter, we propose a helicity measurement to detect primordial chiral violation. We point out that observations of halo-galaxy angular momentum directions (spins), which are frozen in during the galaxy formation process, provide a fossil chiral observable.