The Disk and Dark Halo Mass of the Barred Galaxy NGC 4123. II. Fluid-Dynamical Models
| dc.creator | Weiner, Benjamin J. | |
| dc.creator | Sellwood, J. A. | |
| dc.creator | Williams, T. B. | |
| dc.date | 2000-08-14 | |
| dc.date.accessioned | 2026-07-07T11:07:57Z | |
| dc.date.available | 2026-07-07T11:07:57Z | |
| dc.description | We report a dynamical determination of the separate contributions of disk and dark halo masses to the rotation curve of a spiral galaxy. We use fluid-dynamical models of gas flow in the barred galaxy NGC 4123 to constrain the dynamical properties of the galaxy: disk M/L, bar pattern speed, and the central density and scale radius of the dark halo. We derive a realistic barred potential directly from the light distribution. For each model we assume a value of the stellar M/L and a bar pattern speed Omega_p and add a dark halo to fit the rotation curve. We then compute the gas flow velocities with a 2-D gas dynamical code, and compare the model flow patterns to a 2-D velocity field derived from Fabry-Perot observations. The strong shocks and non-circular motions in the observed gas flow require a high stellar M/L and a fast-rotating bar. Models with I-band disk M/L of 2.0 -- 2.5 h_75, or 80 -- 100% of the maximum disk value, are highly favored. The corotation radius of the bar must be <= 1.5 times the bar semi-major axis. These results contradict some recent claimed ``universal'' galaxy disk/halo relations, since NGC 4123 is of modest size (rotation curve maximum 145 km/sec, and V_flat = 130 km/sec) yet is quite disk-dominated. The dark halo of NGC 4123 is less concentrated than favored by current models of dark halos based on cosmological simulations. Since some 30% of bright disk galaxies are strongly barred and have dust lanes indicating shock morphology similar to that of NGC 4123, it is likely that they also have high stellar M/L and low density halos. We suggest that luminous matter dominates inside the optical radius R_25 of high surface brightness disk galaxies. | |
| dc.description | accepted by ApJ, 20 pages, 11 figures (2 color), uses emulateapj.sty, onecolfloat.sty | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0008205 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0008205 | |
| dc.identifier | Astrophys.J.546:931-951,2001 | |
| dc.identifier | doi:10.1086/318289 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/189977 | |
| dc.subject | Astrophysics | |
| dc.title | The Disk and Dark Halo Mass of the Barred Galaxy NGC 4123. II. Fluid-Dynamical Models | |
| dc.type | text |