The baryonic and dark matter properties of high-redshift gravitationally lensed disc galaxies (original) (raw)
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Rotation Curves inz∼ 1–2 Star-forming Disks: Evidence for Cored Dark Matter Distributions
The Astrophysical Journal, 2020
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.
The universal rotation curve of dwarf disc galaxies
Monthly Notices of the Royal Astronomical Society, 2016
We use the concept of the spiral rotation curves universality to investigate the luminous and dark matter properties of the dwarf disc galaxies in the local volume (size ∼11 Mpc). Our sample includes 36 objects with rotation curves carefully selected from the literature. We find that, despite the large variations of our sample in luminosities (∼2 of dex), the rotation curves in specifically normalized units, look all alike and lead to the lower mass version of the universal rotation curve of spiral galaxies found in Persic et al. We mass model the double normalized universal rotation curve V(R/R opt)/V opt of dwarf disc galaxies: the results show that these systems are totally dominated by dark matter whose density shows a core size between 2 and 3 stellar disc scalelengths. Similar to galaxies of different Hubble types and luminosities, the core radius r 0 and the central density ρ 0 of the dark matter halo of these objects are related by ρ 0 r 0 ∼ 100 M pc −2. The structural properties of the dark and luminous matter emerge very well correlated. In addition, to describe these relations, we need to introduce a new parameter, measuring the compactness of light distribution of a (dwarf) disc galaxy. These structural properties also indicate that there is no evidence of abrupt decline at the faint end of the baryonic to halo mass relation. Finally, we find that the distributions of the stellar disc and its dark matter halo are closely related.
Monthly Notices of the Royal Astronomical Society
We investigate the properties of the baryonic and the dark matter components in low surface brightness (LSB) disc galaxies, with central surface brightness in the B band μ0 ≥ 23 mag arcsec−2. The sample is composed by 72 objects, whose rotation curves show an orderly trend reflecting the idea of a universal rotation curve (URC) similar to that found in the local high surface brightness (HSB) spirals in previous works. This curve relies on the mass modelling of the coadded rotation curves, involving the contribution from an exponential stellar disc and a Burkert cored dark matter halo. We find that the dark matter is dominant especially within the smallest and less luminous LSB galaxies. Dark matter halos have a central surface density Σ0 ∼ 100 M⊙pc−2, similar to galaxies of different Hubble types and luminosities. We find various scaling relations among the LSBs structural properties which turn out to be similar but not identical to what has been found in HSB spirals. In addition, t...
The universal rotation curve of dwarf disk galaxies
2016
We use the concept of the spiral rotation curves universality to investigate the luminous and dark matter properties of the dwarf disc galaxies in the local volume (size ∼11 Mpc). Our sample includes 36 objects with rotation curves carefully selected from the literature. We find that, despite the large variations of our sample in luminosities (∼ 2 of dex), the rotation curves in specifically normalized units, look all alike and lead to the lower-mass version of the universal rotation curve of spiral galaxies found in Persic et al. We mass model the double normalized universal rotation curve V(R/R_opt)/V_opt of dwarf disc galaxies: the results show that these systems are totally dominated by dark matter whose density shows a core size between 2 and 3 stellar disc scale lengths. Similar to galaxies of different Hubble types and luminosities, the core radius r_0 and the central density ρ_0 of the dark matter halo of these objects are related by ρ_0 r_0 ∼ 100M_ pc^-2. The structural pro...
Disk galaxy rotation curves and dark matter distribution
Current Science 25 Apr 2008 vol.94 no.8 pp.960,986-95, 2008
After explaining the motivation for this article, I briefly recapitulate the methods used to determine,somewhat coarsely, the rotation curves of our Milky Way Galaxy and other spiral galaxies, especially in their outer parts, and the results of applying these methods. Recent observations and models of the very inner central parts of galaxian rotation curves are only briefly described. I then present the essential Newtonian theory of (disk) galaxy rotation curves. The next two sections present two numerical simulation schemes and brief results. Application of modified Newtonian dynamics to the outer parts of disk galaxies is then described. Finally, attempts to apply Einsteinian general relativity to the dynamics are summarized. The article ends with a summary and prospects for further work in this area.
The Dark Matter Distribution in Disk Galaxies
Monthly Notices of The Royal Astronomical Society, 2001
We use high-quality optical rotation curves of 9 low-luminosity disk galaxies to obtain the velocity profiles of the surrounding dark matter halos. We find that they increase linearly with radius at least out to the edge of the stellar disk, implying that, over the entire stellar region, the density of the dark halo is about constant.
Rotating Disk Galaxies without Dark Matter Based on Scientific Reasoning
Galaxies
The most cited evidence for (non-baryonic) dark matter has been an apparent lack of visible mass to gravitationally support the observed orbital velocity of matter in rotating disk galaxies, yet measurement of the mass of celestial objects cannot be straightforward, requiring theories derived from the known physical laws along with some empirically established semi-quantitative relationship. The most reliable means for determining the mass distribution in rotating disk galaxies is to solve a force balance equation according to Newton’s laws from measured rotation curves, similar to calculating the Sun’s mass from the Earth’s orbital velocity. Another common method to estimate galactic mass distribution is to convert measured brightness from surface photometry based on empirically established mass-to-light ratio. For convenience, most astronomers commonly assumed a constant mass-to-light ratio for estimation of the so-called “luminous” or “visible” mass, which would not likely be acc...
Monthly Notices of the Royal Astronomical Society, 2007
We present rotation curves for 19 early-type disc galaxies (S0-Sab). The galaxies span a B-band absolute magnitude range from −17.5 to −22, but the majority have a high luminosity with M B < −20. Rotation velocities are measured from a combination of H I velocity fields and long-slit optical emission line spectra along the major axis; the resulting rotation curves probe the gravitational potential on scales ranging from 100 pc to 100 kpc. We find that the rotation curves generally rise rapidly in the central regions and often reach rotation velocities of 200-300 km s −1 within a few hundred parsecs of the centre. The detailed shape of the central rotation curves shows a clear dependence on the concentration of the stellar light distribution and the bulge-to-disc luminosity ratio: galaxies with highly concentrated stellar light distributions reach the maximum in their rotation curves at relatively smaller radii than galaxies with small bulges and a relatively diffuse light distribution. We interpret this as a strong indication that the dynamics in the central regions are dominated by the stellar mass. At intermediate radii, many rotation curves decline, with the asymptotic rotation velocity typically 10-20 per cent lower than the maximum. The strength of the decline is correlated with the total luminosity of the galaxies, more luminous galaxies having on average more strongly declining rotation curves. At large radii, however, all declining rotation curves flatten out, indicating that substantial amounts of dark matter must be present in these galaxies too. A comparison of our rotation curves with the Universal Rotation Curve from Persic et al. reveals large discrepancies between the observed and predicted rotation curves; we argue that rotation curves form a multiparameter family which is too complex to describe with a simple formula depending on total luminosity only. In a number of galaxies from our sample, there is evidence for the presence of rapidly rotating gas in the inner few hundred parsecs from the centres. The inferred central masses and mass densities are too high to be explained by the observed stellar components and suggest the presence of supermassive black holes in these galaxies.
The universal rotation curve of spiral galaxies — I. The dark matter connection
Monthly Notices of the Royal Astronomical Society, 1996
We use a homogeneous sample of about 1100 optical and radio rotation curves (RCs) and relative surface photometry to investigate the main mass structure properties of spirals, over a range of 6 mag and out to ≾ 1.5 and 2 optical radii (for the optical and radio data, respectively). We confirm the strong dependence on luminosity for both the profile and the amplitude of RCs claimed by Persic & Salucci. Spiral RCs show the striking feature that a single global parameter, e.g. luminosity, dictates the rotational velocity at any radius for any object, so revealing the existence of a universal RC. At high luminosities, there is a slight discrepancy between the profiles of RCs and those predicted from the luminous matter (LM) distributions: this implies a small, yet detectable, amount of dark matter (DM). At low luminosities, the failure of the LM prediction is much more severe, and the DM is the only relevant mass component. We show that the universal RC implies a number of scaling prope...