Distances and peculiar velocities of spiral galaxies in the 2MFGC and SFI plus plus samples

摘要

We compare infrared Tully-Fisher (TF) distances and peculiar velocities derived for spiral galaxies from the two largest datasets: the 2MASS selected Flat Galaxy Catalog 2MFGC and the Arecibo General Catalog with I-band photometry, SFI++. These samples contain peculiar velocities for similar to 3000 and similar to 4000 objects, respectively. Based on a sub-sample of similar to 1000 common very inclined galaxies, we reach the following conclusions. Irrespective of high (SFI++) or low (2MFGC) quality of the photometric data used, both the samples have similar to 10% fraction of galaxies deviating considerably from the main body of the TF relation. After their deletion, the standard TF scatter drops to 0(m).47 (2MFGC) and 0(m).40 (SFI++). The TF distances, derived from two samples, demonstrate a high degree of mutual agreement with a correlation coefficient rho = +0.95 and sigma(H (0) r ) = 837 km/s. Peculiar velocities of the galaxies are also correlated with rho = 0.56-0.59 and sigma(V (pec) ) = 610 V (pec) km/s. We find that the bulk motion of the 2MFGC and SFI++ galaxies on a typical scale of H (0) r a parts per thousand 5700 km/s can be represented by a dipole solution with the amplitude V = (297 +/- 23) km/s directed towards {l = 292(0) +/- 4(0), b = -12(0) +/- 3(0)}, being only slightly sensitive to different modifications of the TF relaton.