Abstract

Abstract We present spatially resolved H i kinematics of 32 spiral galaxies which have Cepheid or/and tip of the red giant branch distances, and define a calibrator sample for the Tully–Fisher relation. The interferometric H i data for this sample were collected from available archives and supplemented with new Giant Metrewave Radio Telescope observations. This paper describes a uniform analysis of the H i kinematics of this inhomogeneous data set. Our main result is an atlas for our calibrator sample that presents global H i profiles, integrated H i column-density maps, H i surface-density profiles and, most importantly, detailed kinematic information in the form of high-quality rotation curves derived from highly resolved, two-dimensional velocity fields and position–velocity diagrams.

Highlights

  • The Tully–Fisher relation (TFr) is one of the main scaling relations for rotationally supported galaxies, describing an empirical correlation between the luminosity or visible mass of a spiral galaxy and its rotational velocity or dynamical mass (Tully & Fisher 1977)

  • (3) Only galaxies with regular global H I profiles were included to avoid confusion or contribution by companion galaxies to the flux. We emphasize that these criteria were applied to the zero-point calibrator sample by TC12, who did not consider the merits of detailed H I kinematics for their sample galaxies

  • We note that the systematic difference we find is very close to an empirical correction of 3◦ as determined by Aaronson, Mould & Huchra (1980), which was usually applied when interpreting optical and kinematical inclination angles

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Summary

INTRODUCTION

The Tully–Fisher relation (TFr) is one of the main scaling relations for rotationally supported galaxies, describing an empirical correlation between the luminosity or visible mass of a spiral galaxy and its rotational velocity or dynamical mass (Tully & Fisher 1977). Measurement errors, such as uncertainties on a galaxy’s inclination and/or rotational velocity, combined with a certain intrinsic scatter are responsible for the total observed scatter It was shown by Verheijen (2001), with a study of nearly equidistant spiral galaxies in the Ursa Major cluster with deep K -band photometry, that the observed scatter in the TFr can be reduced significantly when the measured velocity of the outer, flat part of the H I rotation curve (Vflat) is used instead of the rotational velocity as estimated from the width of the global H I profile. We investigate the differences between three measures of the rotational velocity of spiral galaxies: The rotational velocity from the corrected width of the global H I profile, the maximal rotation velocity of the rotation curve (Vmax) and the rotational velocity of the outer flat part of the rotation curve (Vflat) The effects of these different velocity measures on the observed scatter and the intrinsic properties of the TFr will be discussed in a forthcoming paper. The atlas is described in the Appendix, together with notes on individual galaxies

THE SAMPLE
H I kinematics of Tully–Fisher calibrators 4053
DATA COLLECTION AND ANALYSIS
The GMRT data
Homogenization of the sample
Global H I profiles
Integrated H I fluxes
Line widths and rotational velocities
Velocity fields
Rotation curves and velocity field models
Comparison of different velocity measures
Total H I maps and radial H I surface-density profiles
GLOBAL H I PROPERTIES
The masses and sizes of H I discs
H I mass versus luminosity and Hubble type
Radial surface-density profiles
Findings
SUMMARY
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