The shapes of the rotation curves of star-forming galaxies over the last ≈10 Gyr
Monthly Notices of the Royal Astronomical Society Oxford University Press 485:1 (2019) 934-960
Abstract:
We analyse maps of the spatially resolved nebular emission of ≈1500 star-forming galaxies at z ≈ 0.6–2.2 from deep K-band Multi-Object Spectrograph and MUSE observations to measure the average shape of their rotation curves. We use these to test claims for declining rotation curves at large radii in galaxies at z ≈ 1–2 that have been interpreted as evidence for an absence of dark matter. We show that the shape of the average rotation curves, and the extent to which they decline beyond their peak velocities, depends upon the normalization prescription used to construct the average curve. Normalizing in size by the galaxy stellar disc-scale length after accounting for seeing effects (R d), we construct stacked position-velocity diagrams that trace the average galaxy rotation curve out to 6R d (≈13 kpc, on average). Combining these curves with average H I rotation curves for local systems, we investigate how the shapes of galaxy rotation curves evolve over ≈10 Gyr. The average rotation curve for galaxies binned in stellar mass, stellar surface mass density and/or redshift is approximately flat, or continues to rise, out to at least 6R d. We find a trend between the outer slopes of galaxies’ rotation curves and their stellar mass surface densities, with the higher surface density systems exhibiting flatter rotation curves. Drawing comparisons with hydrodynamical simulations, we show that the average shapes of the rotation curves for our sample of massive, star-forming galaxies at z ≈ 0–2.2 are consistent with those expected from lambda cold dark matter theory and imply dark matter fractions within 6Rd of at least ≈60 per cent.KROSS–SAMI: a direct IFS comparison of the Tully–Fisher relation across 8 Gyr since z ≈ 1
Monthly Notices of the Royal Astronomical Society Oxford University Press 482:2 (2018) 2166-2188
Abstract:
We construct Tully–Fisher relations (TFRs), from large samples of galaxies with spatially resolved H α emission maps from the K-band Multi-Object Spectrograph (KMOS) Redshift One Spectroscopic Survey (KROSS) at z ≈ 1. We compare these to data from the Sydney-Australian-Astronomical-Observatory Multi-object Integral-Field Spectrograph (SAMI) Galaxy Survey at z ≈ 0. We stringently match the data quality of the latter to the former, and apply identical analysis methods and sub-sample selection criteria to both to conduct a direct comparison of the absolute K-band magnitude and stellar mass TFRs at z ≈ 1 and 0. We find that matching the quality of the SAMI data to that of KROSS results in TFRs that differ significantly in slope, zero-point, and (sometimes) scatter in comparison to the corresponding original SAMI relations. These differences are in every case as large as or larger than the differences between the KROSS z ≈ 1 and matched SAMI z ≈ 0 relations. Accounting for these differences, we compare the TFRs at z ≈ 1 and 0. For disc-like, star-forming galaxies we find no significant difference in the TFR zero-points between the two epochs. This suggests the growth of stellar mass and dark matter in these types of galaxies is intimately linked over this ≈8 Gyr period.SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES). II. Structural Properties and Near-infrared Morphologies of Faint Submillimeter Galaxies
ASTROPHYSICAL JOURNAL 865:2 (2018) ARTN 103
Resolving the nuclear obscuring disk in the Compton-thick Seyfert galaxy NGC 5643 with ALMA
Astrophysical Journal American Astronomical Society 859:2 (2018) 144
Abstract:
We present ALMA Band 612CO(2-1) line and rest-frame 232 GHz continuum observations of the nearby Compton-thick Seyfert galaxy NGC 5643 with angular resolutions 0.″11-0.″26 (9-21 pc). The CO(2-1) integrated line map reveals emission from the nuclear and circumnuclear region with a two-arm nuclear spiral extending ∼10″ on each side. The circumnuclear CO(2-1) kinematics can be fitted with a rotating disk, although there are regions with large residual velocities and/or velocity dispersions. The CO(2-1) line profiles of these regions show two different velocity components. One is ascribed to the circular component and the other to the interaction of the AGN outflow, as traced by the [O iii]λ5007 Åemission, with molecular gas in the disk a few hundred parsecs from the AGN. On nuclear scales, we detected an inclined CO(2-1) disk (diameter 26 pc, FWHM) oriented almost in a north-south direction. The CO(2-1) nuclear kinematics can be fitted with a rotating disk that appears to be tilted with respect to the large-scale disk. There are strong non-circular motions in the central 0.″2-0.″3 with velocities of up to 110 km s-1. In the absence of a nuclear bar, these motions could be explained as radial outflows in the nuclear disk. We estimate a total molecular gas mass for the nuclear disk of M(H2) = 1.1 ×107Moand an H2column density toward the location of the AGN of N(H2) ∼ 5 ×1023cm-2, for a standard CO-to-H2conversion factor. We interpret this nuclear molecular gas disk as the obscuring torus of NGC 5643 as well as the collimating structure of the ionization cone.The JWST Extragalactic Mock Catalog: Modeling Galaxy Populations from the UV through the Near-IR over 13 Billion Years of Cosmic History
Astrophysical Journal, Supplement Series 236:2 (2018)