2021MNRAS.504.1304S

We study the bulk flow of the local universe with Type Ia supernova data (a compilation of Union2 and Pantheon data) in the spatially flat homogeneous and isotropic space-time. In particular, we take the so-called QCDM models, which consist of cold dark matter (CDM) and a Q-component described by a scalar field with its self-interactions determined by an exponential potential. We use different cumulative redshift slices of the Union2 and Pantheon catalogues. A maximum-likelihood analysis of peculiar velocities confirms that, at low redshifts 0.015 < z < 0.1, the bulk flow is moving in the l=272⁺¹⁷_–17, b=33⁺¹²_–12, and 302⁺²⁰_–20,3⁺¹⁰_–10 directions with v_bulk = 225⁺³⁸_–35 and 246⁺⁶⁴_–46 km s^–1 for the Pantheon and Union2 data respectively, in good agreement with the direction of the cosmic microwave background dipole and with a number of previous studies at 1σ. However, for high redshifts 0.1 < z < 0.2, we get v_bulk = 708⁺¹¹⁰_–110 and v_bulk=1014⁺⁸⁶_–114 kms^–1 towards l = 318 ± 10°, b = -15 ± 9° and l=254⁺¹⁶_–14, b=6⁺⁷_–10 for the Pantheon and Union2 data respectively. This indicates that for low redshifts our results are approximately consistent with the ΛCDM model; however, for high redshifts they disagree with ΛCDM and support the results of those studies that report a large bulk flow for the universe.