Declining Rotation Curves at z = 2 in ΛCDM Galaxy Formation Simulations

Teklu, Adelheid F.; Remus, Rhea-Silvia; Dolag, K.; Arth, Alexander; Burkert, Andreas; Obreja, Aura; Schulze, Felix

doi:10.3847/2041-8213/aaaeb4

Cited by 30 publications

(28 citation statements)

References 30 publications

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“…This relation, therefore, provides a new independent measure of the dark matter mass, that can be used together with other stellar and gas kinematic tracers to properly test the current ΛCDM model (e.g. Bradford et al 2016;Brooks et al 2017;Teklu et al 2018). Though powerful, Equations 1 or 2 are not easy to apply to observational data because in extragalactic observations it is still hard to disentangle the kinematics of the thin stellar discs from those of the thick counterparts.…”

Section: Circular Velocity Vs Rotational Velocitymentioning

confidence: 99%

NIHAO XVI: the properties and evolution of kinematically selected discs, bulges, and stellar haloes

Obreja

Dutton

Macciò

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We use 25 simulated galaxies from the NIHAO project to define and characterize a variety of kinematic stellar structures: thin and thick discs, large scale single discs, classical and pseudo bulges, spheroids, inner discs, and stellar haloes. These structures have masses, spins, shapes and rotational support in good agreement with theoretical expectations and observational data. Above a dark matter halo mass of 2.5×10 11 M , all galaxies have a classical bulge and 70% have a thin and thick disc. The kinematic (thin) discs follow a power-law relation between angular momentum and stellar mass J * = 3.4M 1.26±0.06 * , in very good agreement with the prediction based on the empirical stellar-to-halo mass relation in the same mass range, and show a strong correlation between maximum 'observed' rotation velocity and dark matter halo circular velocity v c = 6.4v 0.64±0.04 max . Tracing back in time these structures' progenitors, we find all to lose a fraction 1−f j of their maximum angular momentum. Thin discs are significantly better at retaining their high-redshift spins (f j ∼ 0.70) than thick ones (f j ∼ 0.40). Stellar haloes have their progenitor baryons assembled the latest (z 1/2 ∼ 1.1) and over the longest timescales (τ ∼ 6.2 Gyr), and have the smallest fraction of stars born in-situ (f in−situ = 0.35 ± 0.14). All other structures have 1.5 z 1/2 3, τ = 4 ± 2 Gyr and f in−situ 0.9.

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Section: Circular Velocity Vs Rotational Velocitymentioning

confidence: 99%

NIHAO XVI: the properties and evolution of kinematically selected discs, bulges, and stellar haloes

Obreja

Dutton

Macciò

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…We conclude by noting that our finding of a flat rotation curve may not be inconsistent with the conclusions of Lang et al (2017). The majority of disk galaxies in cosmological hydrodynamic simulations by Teklu et al (2018) exhibit flat rotation curves with only 38% hosting declining rotation curves. Lang et al (2017) split their data out into two subsamples according to the degree of pressure support, one with V rot /σ 0 > 6.3 and the other < 6.3.…”

Section: Massesmentioning

confidence: 99%

“…When combined with a light profile and a mass-to-light ratio, one may estimate the distribution of dark matter in a galaxy (e.g. Carignan & Freeman 1985;van Albada et al 1985;Kassin et al 2006;de Blok et al 2008;Korsaga et al 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Different simulations also make different predictions about the shapes of rotation curves at z > 1. Teklu et al (2018) find 38% of disk galaxies with M > 5 × 10 10 M at z = 2 in the cosmological hydrodynamic simulation, Magneticum Pathfinder (K. Dolag et al, in preparation) have declining rotation beyond ∼4 kpc (as estimated from Figure 4 in Teklu et al 2018). In contrast, the Illus-trisTNG cosmological hydrodynamic simulations (Lovell et al 2018) show initially declining rotation curves at z = 2 that gradually flatten in the outer disk, similar to low-z disk galaxies.…”

Section: Introductionmentioning

confidence: 99%

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Evidence of a Flat Outer Rotation Curve in a Star-bursting Disk Galaxy at z = 1.6

Drew

Casey

Burnham

et al. 2018

ApJ

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Observations of the baryon to dark matter fraction in galaxies through cosmic time are a fundamental test for galaxy formation models. Recent observational studies have suggested that some disk galaxies at z > 1 host declining rotation curves, in contrast with observations of low redshift disk galaxies where stellar or HI rotation curves flatten at large radii. We present an observational counterexample, a galaxy named DSFG850.95 at z = 1.555 (4.1 Gyr after the big bang) that hosts a flat rotation curve between radii of ∼6-14 kpc (1.2-2.8 disk scale lengths) and has a dark matter fraction of 0.44±0.08 at the H-band half light radius, similar to the Milky Way. We create position-velocity and position-dispersion diagrams using Keck/MOSFIRE spectroscopic observations of Hα and [NII] emission features, which reveal a flat rotation velocity of V flat = 285±12 km s −1 and an ionized gas velocity dispersion of σ 0 = 48±4 km s −1 . This galaxy has a rotation-dominated velocity field with V flat /σ 0 ∼ 6. Ground-based H-band imaging reveals a disk with Sérsic index of 1.29±0.03, an edgeon inclination angle of 87±2 • , and an H-band half light radius of 8.4±0.1 kpc. Our results point to DSFG850.95 being a massive, rotationally-supported disk galaxy with a high dark-matter-to-baryon fraction in the outer galaxy, similar to disk galaxies at low redshift.

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“…In particular, the amount of dark matter fraction within the stellar half-mass radius has been shown to be strongly dependent on the implementation of feedback processes (e.g. Wu et al 2014;Remus et al 2017;Teklu et al 2018). For example, different simulations (e.g.…”

Section: Introductionmentioning

confidence: 99%

A novel 3D technique to study the kinematics of lensed galaxies

Rizzo

Vegetti

Fraternali

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present a 3D Bayesian method to model the kinematics of strongly lensed galaxies from spatially-resolved emission-line observations. This technique enables us to simultaneously recover the lens-mass distribution and the source kinematics directly from the 3D data cube. We have tested this new method with simulated OSIRIS observations for nine star-forming lensed galaxies with different kinematic properties. The simulated rotation curves span a range of shapes which are prototypes of different morphological galaxy types, from dwarf to massive spiral galaxies. We have found that the median relative accuracy on the inferred lens and kinematic parameters are at the level of 1 and 2 per cent, respectively. We have also tested the robustness of the technique against different inclination angles, signal-to-noise ratios, the presence of warps or non-circular motions and we have found that the accuracy stays within a few per cent in most cases. This technique represents a significant step forward with respect to the methods used until now, as the lens parameters and the kinematics of the source are derived from the same 3D data. This enables us to study the possible degeneracies between the two and estimate the uncertainties on all model parameters consistently.

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Declining Rotation Curves at z = 2 in ΛCDM Galaxy Formation Simulations

Cited by 30 publications

References 30 publications

NIHAO XVI: the properties and evolution of kinematically selected discs, bulges, and stellar haloes

NIHAO XVI: the properties and evolution of kinematically selected discs, bulges, and stellar haloes

Evidence of a Flat Outer Rotation Curve in a Star-bursting Disk Galaxy at z = 1.6

A novel 3D technique to study the kinematics of lensed galaxies

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