SFI++ II: A New I-band Tully-Fisher Catalog, Derivation of Peculiar Velocities and Dataset Properties

TL;DR

The paper introduces the SFI++ catalog, a comprehensive dataset of galaxy properties and velocities derived from multiple observational sources, enabling detailed analysis of large-scale cosmic flows.

Contribution

It presents a new, homogeneous catalog of galaxy distances and velocities, incorporating advanced grouping and bias correction techniques for improved accuracy.

Findings

A catalog of 4861 galaxies with derived distances and velocities.

Application of advanced grouping algorithms to reduce velocity scatter.

Corrections for Malmquist bias using large-scale structure data.

Abstract

We present the SFI++ dataset, a homogeneously derived catalog of photometric and rotational properties and the Tully-Fisher distances and peculiar velocities derived from them. We make use of digital optical images, optical long-slit spectra, and global HI line profiles to extract parameters of relevance to disk scaling relations, incorporating several previously published datasets as well as a new photometric sample of some 2000 objects. According to the completeness of available redshift samples over the sky area, we exploit both a modified percolation algorithm and the Voronoi-Delaunay method to assign individual galaxies to groups as well as clusters, thereby reducing scatter introduced by local orbital motions. We also provide corrections to the peculiar velocities for both homogeneous and inhomogeneous Malmquist bias, making use of the 2MASS Redshift Survey density field to approximate large scale structure. We summarize the sample selection criteria, corrections made to raw observational parameters, the grouping techniques, and our procedure for deriving peculiar velocities. The final SFI++ peculiar velocity catalog of 4861 field and cluster galaxies is large enough to permit the study not just of the global statistics of large scale flows but also of the {\it details} of the local velocity field.