Rotation Curves in z ∼ 1–2 Star-forming Disks: Evidence for Cored Dark Matter Distributions

Abstract

We report high quality, Hα or CO rotation curves (RCs) to several Re for 41 large, massive, star-forming disk galaxies (SFGs), across the peak of cosmic galaxy evolution (z~0.67-2.45), taken with the ESO-VLT, the LBT and IRAM-NOEMA. Most RC41 SFGs have reflection symmetric RCs plausibly described by equilibrium dynamics. We fit the major axis position-velocity cuts with beam-convolved, forward modeling with a bulge, a turbulent rotating disk, and a dark matter (DM) halo. We include priors for stellar and molecular gas masses, optical light effective radii and inclinations, and DM masses from abundance matching scaling relations. Two-thirds or more of the z ³ 1.2 SFGs are baryon dominated within a few Re of typically 5.5 kpc, and have DM fractions less than maximal disks (<fDM (Re) > = 0.12). At lower redshift (z<1.2) that fraction is less than one-third. DM fractions correlate inversely with the baryonic angular momentum parameter, baryonic surface density and bulge mass. Inferred low DM fractions cannot apply to the entire disk & halo but more plausibly reflect a flattened, or cored, inner DM density distribution. The typical central 'DM deficit' in these cores relative to NFW distributions is ~30 % of the bulge mass. The observations are consistent with rapid radial transport of baryons in the first generation massive gas rich halos forming globally gravitationally unstable disks, and leading to efficient build-up of massive bulges and central black holes. A combination of heating due to dynamical friction and AGN feedback may drive DM out of the initial cusps.

Rotation Curves of Galaxies and Their Dependence on Morphology and Stellar Mass

“…Therefore, V DM (r) is determined by a single parameter M 200 in this simple dark matter halo model. The total circular velocity of the baryonic disk and the dark matter halo model (Burkert et al 2010(Burkert et al , 2016Lang et al 2017;Genzel et al 2020) is calculated by…”

“…Thus, we should take into account the effect of the pressure support in RCs. Assuming the velocity dispersion σ 0 is constant in the exponential disk model in hydrostatic equilibrium, the observed RC (Burkert et al 2010(Burkert et al , 2016Lang et al 2017;Genzel et al 2020;Kretschmer et al 2021) is described by 11). The contributions to the total rotation curve from the dark matter halo (Equation 7) and the baryonic disk (Noordermeer 2008) are indicated by the dashed line and the blue solid line, respectively.…”

A Multiwavelength Study of ELAN Environments (AMUSE$^2$): Detection of a dusty star-forming galaxy within the enormous Lyman $α$ nebula at $z=2.3$ sheds light on its origin

“…, where FWHM is in km s −1 and r e in kpc, and we adopt sin 2 (i) = 2/3 (Tacconi et al 2008). For dark matter fraction, we adopt f DM = 0.12 based on the latest dynamical studies of z ∼ 2 star-forming galaxies with analyses of high-quality rotational curves (Genzel et al 2020). In the bottom-left panel of Figure 3 we plot three lines representing three gas mass fractions respectively, in which we also plot our measurements along with those from the z = 2 − 5 unlensed sources in the literature.…”

The MUSE Extremely Deep Field: Evidence for SFR-induced cores in dark-matter dominated galaxies at z=1

“…Disk-halo decompositions have proven to be possible at z 2 in the pioneering work of Genzel et al (2017) using very deep (> 30 hr) near-IR integral field spectroscopy (IFS) on a small sample of six massive starforming galaxies (SFGs). Exploring lower mass SFGs, this exercise requires a stacking approach (as in Lang et al 2017;Tiley et al 2019) or deep IFS observations (as in Genzel et al 2020). These studies of massive SFGs with M > 10 11 M showed that RCs are declining at large radii, indicative of a low DM fraction within R e ; see also Wuyts et al (2016); Übler et al (2017); Abril-Melgarejo et al (2021) for dynamical estimates of DM fractions.…”