The velocity-distance relation for galaxies on a bubble

We use the I-band Tully-Fisher (TF) relation to measure relative distances to galaxies on the edges of the largest (~5000 km s^-1^) void in the first slice of the Center for Astrophysics redshift survey extension. We divide the data into three samples: H (seven galaxies) on the high-velocity edge of the void, L (10 galaxies) along the low- velocity edge, and P (nine galaxies) distributed nearly along the line of sight adjacent to the Coma cluster. We show that sample P is infalling toward Coma. For samples H and L the scatter about the Hubble diagram is 0. 18ᵐ^, comparable with the error in an individual I-band TF measurement. The ratio of I-band TF distances to the high- and low-velocity boundaries (samples H and L) is 2. 22^+0. 11^_-0. 10_ and the ratio of velocities is 2. 16+/-0. 08. In other words, to within the error the void has the same diameter in real and redshift space. The mean peculiar velocity of sample L is 32+/-108 km s^-1^; for sample H it is -113+/-253 km s^-1^. In other words, the data are consistent with no outflow from the void and the 1σ upper limit to outflow from the void is ~ 5% of the void diameter. For a simple model, the 2σ limits on the outflow yield In OMEGA<~ 1. We detect the "infall" of sample P toward Coma at better than the 3σ level: the line-of-sight component of the infall is 915+/-263 km s^-1^ at a distance of 26 h^-1^ Mpc (H₀_= 100 h km s^-1^ Mpc^-1^) from the center of the Coma cluster. For spherically symmetric infall, the implied value of OMEGA = 2. 2^+20^_-2_; the 2 σ error includes only the error in the infall measurement and ignores the large error in the extrapolated density of the Coma cluster.