Evidence for a Strong End-On Bar in the Ringed Sigma-Drop Galaxy NGC 6503

TL;DR

This study presents multi-wavelength evidence supporting the existence of a strong end-on bar in galaxy NGC 6503, linking photometric and kinematic features to bar-driven structures.

Contribution

It provides the first comprehensive multi-data analysis confirming a strong end-on bar in NGC 6503, challenging previous interpretations of its nuclear features.

Findings

Detection of a sigma-drop indicating a bar-driven dynamical feature

Identification of an inner ring and circumnuclear disk associated with the bar

Reinterpretation of the nuclear star-forming ring as a young inner ring

Abstract

We use WIYN High-resolution Infrared Camera (WHIRC) H (1.6 micron) band imaging, archival Spitzer, HST, and GALEX data, simulations and data from the literature to argue for the presence of a strong end-on bar in nearby spiral galaxy NGC 6503. The evidence consists of both photometric and kinematic signatures as well as resonant structures present in the galaxy which are most often associated with bars. These include a central peak followed by a plateau in the surface brightness profile, an extreme decrement in the central stellar velocity dispersion (a sigma-drop), and the presence of an inner ring as well as a circumnuclear disk with spiral structure. In this framework the previously identified nuclear star-forming ring is instead a young inner ring spanned in diameter by the strong end-on bar.