Schwarzschild modeling of barred s0 galaxy NGC 4371

We apply the barred Schwarzschild method developed by Tahmasebzadeh et al. (2022) to a barred S0 galaxy, NGC 4371, observed by IFU instruments from the TIMER and ATLAS3D projects. We construct the gravitational potential by combining a fixed black hole mass, a spherical dark matter halo, and stellar mass distribution deprojected from 3.6 μm S4G image considering an axisymmetric disk and a triaxial bar. We independently modelled kinematic data from TIMER and ATLAS3D. Both models fit the data remarkably well. We find a consistent bar pattern speed from the two sets of models with Ωp = 23.6 ± 2.8 km s−1 kpc−1 and Ωp = 22.4 ± 3.5 km s−1 kpc−1, respectively. The dimensionless bar rotation parameter is determined to be R ≡ Rcor/Rbar=1.88 ± 0.37, indicating a likely slow bar in NGC 4371. Additionally, our model predicts a high amount of dark matter within the bar region (MDM/Mtotal ∼0.51 ± 0.06), which, aligned with the predictions of cosmological simulations, indicates that fast bars are generally found in baryon-dominated disks. Based on the best-fitting model, we further decompose the galaxy into multiple 3D orbital structures, including a BP/X bar, a classical bulge, a nuclear disk, and a main disk. The BP/X bar is not perfectly included in the input 3D density model, but BP/X-supporting orbits are picked through the fitting to the kinematic data. This is the first time a real barred galaxy has been modelled utilizing the Schwarzschild method including a 3D bar.