The gravitational potential of the bar in NGC 4314

Abstract

We present near-infrared images of NGC 4314 in the J, H, and K bands. Colors in these bands are constant across the bar of NGC 4314, indicating that the mass-to-light ratio is constant over much of the galaxy. We have developed an efficient procedure for mapping the gravitational potential of a nonaxisymmetric galaxy based on its appearance in the near-infrared using a Fourier transform method. We account for the thickness of the galaxy's stellar disk by convolving its K image with a function that depends upon the vertical stellar scale height. We apply this procedure to NGC 4314 and find that prograde orbits integrated in the potential are consistent with the shape of the bar for a disk vertical scale height of h = 350 +/- 100 pc and a corotation radius of r = 3.5 +/- 0.5 kpc. We find that the inner m = 4 Lindblad resonance is approximately at the location of knoblike features seen near the end of the bar. The shape of nearly closed orbits at this radius are lozenge or diamond shaped and have low speeds along the major axis of the bar. The low speeds imply an increase in density along the major axis of the bar. The angle of the major axis of the m = 4 component of the surface density begins to twist at the location of its resonance, and the angle of the m = 2 component begins to twist at a larger radius near the corotation radius.