NIR Tully-Fisher in the Zone of Avoidance. - II. 21 cm HI-line spectra of southern ZOA galaxies

TL;DR

This paper presents high-accuracy HI line spectra and linewidth measurements for inclined spiral galaxies in the southern Zone of Avoidance, enabling improved peculiar velocity and flow field studies in a key cosmic region.

Contribution

It provides a systematically reduced and parameterized set of HI spectra for 394 galaxies, with conversion equations between linewidth measurements, facilitating Tully-Fisher distance estimates.

Findings

394 HI spectra analyzed and parameterized systematically

342 galaxies suitable for Tully-Fisher distance estimation

Enhanced data for flow field analysis in the southern ZOA

Abstract

High-accuracy HI profiles and linewidths are presented for inclined ($(b/a)^o < 0.5$) spiral galaxies in the southern Zone of Avoidance (ZOA). These galaxies define a sample for use in the determinations of peculiar velocities using the near-infrared Tully-Fisher (TF) relation. The sample is based on the 394 HI-selected galaxies from the Parkes HI Zone of Avoidance survey (HIZOA). Follow-up narrow-band Parkes HI observations were obtained in 2010 and 2015 for 290 galaxies, while for the further 104 galaxies, sufficiently high signal-to-noise spectra were available from the original HIZOA data. All 394 spectra are reduced and parameterized in the same systematic way. Five different types of linewidth measurements were derived, and a Bayesian mixture model was used to derive conversion equations between these five widths. Of the selected and measure galaxies, 342 have adequate signal-to-noise (S/N $\geq$ 5) for use in TF distance estimation. The average value of the signal-to-noise ratio of the sample is 14.7. We present the HI parameters for these galaxies. The sample will allow a more accurate determination of the flow field in the southern ZOA which bisects dynamically important large-scale structures such as Puppis, the Great Attractor, and the Local Void.