High resolution spectroscopy of the BCD galaxy Haro 15:I. Internal kinematics

TL;DR

This study uses high-resolution spectroscopy to analyze the internal kinematics of the nebular material in Haro 15, revealing complex emission profiles, multiple kinematic components, and confirming galactic rotation and virialization among the knots.

Contribution

It provides a detailed kinematic analysis of Haro 15's knots, highlighting the importance of multiple components in understanding starburst dynamics and galaxy motion.

Findings

Presence of broad and narrow kinematic components in emission lines.

Knots follow the virial relation, indicating gravitational equilibrium.

Multiple kinematic components significantly impact parameter analysis.

Abstract

Using echelle spectroscopy, obtained at Las Campanas Observatory, we present a detailed study of the internal kinematics of the nebular material in multiple knots of the blue compact dwarf galaxy Haro 15. A detailed analysis of the complex emission line profiles show the presence of an underlying broad component in almost all knots, and the brightest star-forming region shows unmistakable signs for the presence of two distinct narrow kinematical components. We also study the information that our analysis provides regarding the motion of the individual knots in the Haro 15 galaxy potential, confirming that they follow galactic rotation. Finally, we examine the relation between their velocity dispersion and luminosity, finding that almost all knots follow the relation for virialised systems. This holds for the strong narrow components identified in complex fits and for single profile fits, although the latter show a flatter slope. In agreement with previous findings, in this paper we show that the existence of multiple kinematical components among massive starbursts cannot be overlooked, as it has a noticeable effect on any subsequent analysis that relies on basic parameters.