Properties of Fast and Slow Bars Classified by Epicyclic Frequency Curves from Photometry of Barred Galaxies

Abstract

We test the idea that bar pattern speeds decrease with time owing to angular momentum exchange with a dark matter halo. If this process actually occurs, then the radii of the corotation resonance and other resonances should generally increase with time. We therefore derive the angular velocity Ω and epicyclic frequency κ as functions of galactocentric radius for 85 barred galaxies using photometric data. Mass maps are constructed by assuming a dynamical mass-to-light ratio and then solving the Poisson equation for the gravitational potential. The locations of Lindblad resonances and the corotation resonance radius are then derived using the standard precession frequency curves in conjunction with bar pattern speeds recently estimated from the Tremaine–Weinberg method as applied to integral field spectroscopy data. Correlations between physical properties of bars and their host galaxies indicate that bar length and the corotation radius depend on the disk circular velocity while bar strength and pattern speed do not. As the bar pattern speed decreases, bar strength, length, and corotation radius increase, but when bars are subclassified into fast, medium, and slow domains, no significant change in bar length is found. Only a hint of an increase in bar strength from fast to slow bars is found. These results suggest that bar length in a galaxy undergoes little evolution, and is determined instead mainly by the size of the host galaxy.

Dynamical Analysis of the Maclaurin Disk with Velocity Dispersion and Its Influence on the Formation of the Bar

“…These anomalies are, similar to the situation for angular motions in Figure 5, attributed to the local instability that perturbs the particle epicyclic motion. In past studies, it was common practice to derive the epicyclic frequency only from the disk gravitational potential, both in simulations (Dehnen 1999;Rautiainen & Salo 2000;Saha & Jog 2014;Wu et al 2016;Vasiliev 2019) and in observations (Monari et al 2019;Kawata et al 2021;Lee et al 2022). On the other hand, some other studies measured it directly (Athanassoula 2003;Martinez-Valpuesta et al 2006;Dubinski et al 2009).…”

Effects of the Central Mass Concentration on Bar Formation in Disk Galaxies

“…In addition, the bar length depends considerably on the measurement methods such as Fourier analysis, force ratio, ellipse fitting, etc. (Lee et al 2022). Theoretically, it is impossible to have a long-lived, quasisteady bar with <  1 since the bar-supporting x 1 orbits exist only inside the corotation radius (e.g., Contopoulos 1980;Contopoulos & Grosbøl 1989;Binney & Tremaine 2008).…”

From Galactic Bars to the Hubble Tension: Weighing Up the Astrophysical Evidence for Milgromian Gravity

“…For ΛCDM to be consistent with the observed approximate equality between bar length and corotation radius, the bar length would have to rise over time to keep up with the rising corotation radius. However, observed bar lengths evolve little over time [469,470].…”