Details

Autor(en) / Beteiligte

• Blazek, Jonathan A
• McEwen, Joseph E
• Hirata, Christopher M

Titel

Streaming Velocities and the Baryon Acoustic Oscillation Scale

Ist Teil von

• Physical review letters, 2016-03, Vol.116 (12), p.121303-121303, Article 121303

Ort / Verlag

United States: American Physical Society

Erscheinungsjahr

2016

Quelle

American Physical Society Journals

Beschreibungen/Notizen

• At the epoch of decoupling, cosmic baryons had supersonic velocities relative to the dark matter that were coherent on large scales. These velocities subsequently slow the growth of small-scale structure and, via feedback processes, can influence the formation of larger galaxies. We examine the effect of streaming velocities on the galaxy correlation function, including all leading-order contributions for the first time. We find that the impact on the baryon acoustic oscillation (BAO) peak is dramatically enhanced (by a factor of ∼5) over the results of previous investigations, with the primary new effect due to advection: if a galaxy retains memory of the primordial streaming velocity, it does so at its Lagrangian, rather than Eulerian, position. Since correlations in the streaming velocity change rapidly at the BAO scale, this advection term can cause a significant shift in the observed BAO position. If streaming velocities impact tracer density at the 1% level, compared to the linear bias, the recovered BAO scale is shifted by approximately 0.5%. This new effect, which is required to preserve Galilean invariance, greatly increases the importance of including streaming velocities in the analysis of upcoming BAO measurements and opens a new window to the astrophysics of galaxy formation.