Motion of the Local Group of galaxies and isotropy of the Universe

H I observations of 84 nearby Sbc spiral galaxies lying in the redshift range 1,000–5,500 kms−1 have been used to determine the motion of the Sun and the Local Group of galaxies relative to the backdrop of galaxies extending out to 70 Mpc. This study yields a Local Group velocity of 436±55km s−1 towards l = 264°±18°, b = 45°±12°, in close agreement with the value inferred from the dipole anisotropy of the 3 K cosmic microwave background. The agreement shows that most of the dipole anisotropy is locally (extrinsically) induced and is not an intrinsic property of the Universe as has been implied. The component of the Local Group motion in the direction of the Virgo cluster is 410±55 km s−1, a value similar to that derived recently by independent methods. This implies that the local value of the density of the Universe is 0.15–0.50 of that required to close the Universe.