The (dark) halo-to-stellar mass ratio in the Spitzer Survey of Stellar Structure in Galaxies (S$^4$G)

We use 3.6 $\mu$m photometry for 1154 disk galaxies ($i<65^{\circ}$) in the Spitzer Survey of Stellar Structure in Galaxies (S$^{4}$G, Sheth et al. 2010) to obtain the stellar component of the circular velocity. By combining the disk+bulge rotation curves with HI line width measurements from the literature, we estimate the ratio of the halo-to-stellar mass ($M_{\rm halo}/M_{\ast}$) within the optical disk, and compare it to the total stellar mass ($M_{\ast}$). We find the $M_{\rm halo}/M_{\ast}$-$M_{\ast}$ relation in good agreement with the best-fit model at z$\approx$0 in $\Lambda$CDM cosmological simulations (e.g. Moster et al. 2010), assuming that the dark matter halo within the optical radius comprises a constant fraction ($\sim4\%$) of its total mass.
Comment: 6 pages, 2 figures, proceedings of the XII Scientific Meeting of the Spanish Astronomical Society held on July 18-22, 2016, in Bilbao, Spain. F. Figueras, A. S\'anchez-Lavega, S. P\'erez-Hoyos, A. Alonso Herrero, S. Arribas, C. Hern\'andez Monteagudo (eds.)