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Register a new userSeeking the Local Convergence Depth. I. TF Observations of the Clusters A168, A397, A569, A1139, A1228, and A1983
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Daniel A. Dale
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We present first results of an all-sky observing program designed to improve the quality of the I band Tully-Fisher (TF) template and to obtain the reflex motion of the Local Group with respect to clusters to z = 0.06. We are obtaining between 5 and 15 TF measurements per cluster on a sample of 50 clusters at intermediate redshifts (0.02 < z < 0.06). Presentation of the data for seven Abell clusters of galaxies is given here. This data incorporates methods for estimating the true inclination of a spiral disk, an observational parameter undervalued for small angular-sized galaxies or for galaxies observed in poor seeing conditions.
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We present Tully-Fisher (TF) observations for nine rich Abell clusters of galaxies. This is the second such data installment of an all-sky survey of 50 clusters in the redshift range 0.02 < z < 0.06. The data extends the TF study of nearby clusters of Giovanelli et al.; they will be used jointly to determine an accurate I band TF template and to establish a cluster inertial reference frame to z = 0.06.
We present Tully-Fisher observations for 35 rich Abell clusters of galaxies. Results from I band photometry and optical rotation curve work comprise the bulk of this paper. This is the third such data installment of an all-sky survey of 52 clusters in the distance range 50 to 200h Mpc. The complete data set provides the basis for determining an accurate Tully-Fisher template relation and for estimating the amplitude and direction of the local bulk flow on a 100h Mpc scale.
We have obtained I band Tully-Fisher (TF) measurements for 522 late-type galaxies in the fields of 52 rich Abell clusters distributed throughout the sky between 50 and 200h Mpc. Here we estimate corrections to the data for various forms of observational bias, most notably Malmquist and cluster population incompleteness bias. The bias-corrected data are applied to the construction of an I band TF template, resulting in a relation with a dispersion of 0.38 magnitudes and a kinematical zero-point accurate to 0.02 magnitudes. This represents the most accurate TF template relation currently available. Individual cluster TF relations are referred to the average template relation to compute cluster peculiar motions. The line-of-sight dispersion in the peculiar motions is 341+/-93 km/s, in general agreement with that found for the cluster sample of Giovanelli and coworkers.
We have obtained new Tully-Fisher (TF) peculiar velocity measurements for 52 Abell galaxy clusters distributed throughout the sky between ~ 50 and 200 Mpc/h.The measurements are based on I band photometry and optical rotation curves for a sample of 522 spiral galaxies, from which an accurate TF template relation has been constructed. Individual cluster TF relations are referred to the template to compute cluster peculiar motions. The reflex motion of the Local Group of galaxies is measured with respect to the reference frame defined by our cluster sample and the distant portion of the Giovanelli et al. (1998) cluster set. We find the Local Group motion in this frame to be 565+/-113 km/s in the direction (l,b)=(267,26)+/-10 when peculiar velocities are weighted according to their errors. After optimizing the dipole calculation to sample equal volumes equally, the vector is 509+/-195 km/s towards (255,33)+/-22. Both solutions agree, to within 1-sigma or better, with the Local Group motion as inferred from the cosmic microwave background (CMB) dipole. Thus, the cluster sample as a whole moves slowly in the CMB reference frame, its bulk flow being at most 200 km/s.
We present the results of new spectrophotometry and heavy element abundance determinations for 3 dwarf galaxies UM151, UM408 and A1228+12 (RMB132). These galaxies have been claimed in the literature to have very low metallicities, corresponding to log(O/H)+12 < 7.65, that are in the metallicity range of some candidate local young galaxies. We present higher S/N data for these three galaxies. UM151 and UM408 have significantly larger metallicities: log(O/H)+12 = 8.5 and 7.93, respectively. For A1228+12 our new log(O/H)+12 = 7.73 is close to that recalculated from earlier data (7.68). Thus, the rederived metallicities allow us to remove these objects from the list of galaxies with Z < 1/20 Z_Sun.
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