Title | The Velocity-Distance Relation for Galaxies on a Bubble |
Authors | Bothun, Gregory D.; Geller, Margaret J.; Kurtz, Michael J.; Huchra, John P.; Schild, Rudolph E. |
Bibcode | 1992ApJ...395..347B Search ADS ↗ |
Abstract | 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 0.18^m^, 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(H_0_= 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. |
Objects | 78 Objects Search NED ↙ |