Constraining the relative velocity effect using the Baryon Oscillation Spectroscopic Survey

Florian Beutler, Uros Seljak, Zvonimir Vlah

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We analyze the power spectrum of the Baryon Oscillation Spectroscopic Survey (BOSS), Data Release 12 (DR12) to constrain the relative velocity effect, which represents a potential systematic for measurements of the Baryon Acoustic Oscillation (BAO) scale. The relative velocity effect is caused by a relative density δbc between baryons and cold dark matter at decoupling, which sources a relative velocity vbc between the two components. Our power spectrum model includes all 1-loop redshift-space terms corresponding to vbc parameterized by the bias parameter bv2. We also include the linear terms proportional to δbc and θbc which we parameterize with the bias parameters bbcδ and bbcθ. Our data does not support a detection of the relative velocity effect in any of these parameters. Combining the low and high redshift bins of BOSS, we find limits of  bv2=0.012±0.015(±0.031),  bbcδ=−1.0±2.5(±6.2) and  bbcθ=−114±55(±175) with 68% (95%) confidence levels. These constraints restrict the potential systematic shift in DA(z), H(z) and fσ8, due to the relative velocity, to 1%, 0.8% and 2%, respectively. Given the current uncertainties on the BAO measurements of BOSS these shifts correspond to  0.53σ, 0.5σ and 0.22σ for DA(z), H(z) and fσ8, respectively.
Original languageEnglish
Pages (from-to)2723–2735
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Early online date16 May 2017
Publication statusPublished - 21 Sept 2017


  • astro-ph.CO
  • RCUK
  • STFC
  • ST/N00180X/1


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