Galaxy Evolution

Galaxy pairs follow filaments

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Science  14 Dec 2018:
Vol. 362, Issue 6420, pp. 1260-1261
DOI: 10.1126/science.362.6420.1260-a

Spiral galaxy pairs tend to align their spin axes with the direction of the spine of their host cosmic filament.

PHOTO: ESA/HUBBLE & NASA

Galaxies are nonuniformly distributed in the Universe, forming a cosmic web of filaments and clusters. Filaments occupy about 5% of the volume of the Universe but contain about a third of the galaxies, which grow by merging. Mesa et al. identified pairs of neighboring galaxies embedded within filaments. They found that the orientation of the pairs preferentially align with the axes of the surrounding filaments, with the effect being more pronounced for elliptical galaxies than for spirals. Because galaxy spins are known to follow the filament direction, this implies that major merger events have a preferred orientation in this environment.

Astron. Astrophys. 619, A24 (2018).

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