Scale-dependent bias due to primordial vector fields

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Anisotropic stress perturbations induced by primordial Gaussian vector fields create non-Gaussianity in curvature perturbations. We found that such non-Gaussianity closely resembles the local-type non-Gaussianity parametrized by f NL, and generates scale-dependent bias in large-scale structures. We also found a simple relationship between the scale-dependent bias and the power spectrum of the vector fields. When the vector fields are interpreted as primordial magnetic fields, the effective f NL is shown to be always negative. The scale-dependent bias provides a new approach to probing primordial vector fields.