Galaxy formation and evolution

Abstract:

We report a detailed CO(1-0) survey of a galaxy protocluster field at z = 2.16, based on 475 h of observations with the Australia Telescope Compact Array. We constructed a large mosaic of 13 individual pointings, covering an area of 21 arcmin2 and ±6500 km s-1 range in velocity. We obtained a robust sample of 46 CO(1-0) detections spanning z = 2.09 - 2.22, constituting the largest sample of molecular gas measurements in protoclusters to date. The CO emitters show an overdensity at z = 2.12 - 2.21, suggesting a galaxy super-protocluster or a protocluster connected to large-scale filaments of ∼120 cMpc in size. We find that 90% of CO emitters have distances >0.′5-4′ to the center galaxy, indicating that small area surveys would miss the majority of gas reservoirs in similar structures. Half of the CO emitters have velocities larger than escape velocities, which appears gravitationally unbound to the cluster core. These unbound sources are barely found within the R200 radius around the center, which is consistent with a picture in which the cluster core is collapsed while outer regions are still in formation. Compared to other protoclusters, this structure contains a relatively higher number of CO emitters with relatively narrow line widths and high luminosities, indicating galaxy mergers. We used these CO emitters to place the first constraint on the CO luminosity function and molecular gas density in an overdense environment. The amplitude of the CO luminosity function is 1.6 ± 0.5 orders of magnitude higher than that observed for field galaxy samples at z ∼ 2, and one order of magnitude higher than predictions for galaxy protoclusters from semi-analytical SHARK models. We derive a high molecular gas density of 0.6 - 1.3 × 109Mpdbl cMpc-3 for this structure, which is consistent with predictions for cold gas density of massive structures from hydro-dynamical DIANOGA simulations.

Abstract:

We construct a dynamical model of the Milky Way disk from a data set that combines Gaia EDR3 and APOGEE data throughout galactocentric radii in the range 5.0 kpc ≤ R ≤ 19.5 kpc. We make use of the spherically aligned Jeans anisotropic method to model the stellar velocities and their velocity dispersions. Building upon our previous work, our model is now fitted to kinematic maps that have been extended to larger galactocentric radii due to the expansion of our data set, probing the outer regions of the Galactic disk. Our best-fitting dynamical model suggests a logarithmic density slope of αDM = −1.602 ± 0.079syst for the dark matter halo and a dark matter density of ρDM(R⊙) = (8.92 ± 0.56syst) × 10−3 M⊙ pc−3 (0.339 ± 0.022syst GeV cm3). We estimate a circular velocity at the solar radius of vcirc = (234.7 ± 1.7syst) km s−1 with a decline toward larger radii. The total mass density is ρtot(R⊙) = (0.0672 ± 0.0015syst) M⊙ pc−3 with a slope of αtot = −2.367 ± 0.047syst for 5 kpc ≤ R ≤ 19.5 kpc, and the total surface density is Σ(R⊙, ∣z∣ ≤ 1.1 kpc) = (55.5 ± 1.7syst) M⊙ pc−2. While the statistical errors are small, the error budget of the derived quantities is dominated by the three to seven times larger systematic uncertainties. These values are consistent with our previous determination, but the systematic uncertainties are reduced due to the extended data set covering a larger spatial extent of the Milky Way disk. Furthermore, we test the influence of nonaxisymmetric features on our resulting model and analyze how a flaring disk model would change our findings.

Abstract:

This is an erratum to the paper 'Dark matter-deficient dwarf galaxies form via tidal stripping of dark matter in interactions with massive companions', which was published in MNRAS, 502, 1785 (Jackson et al. 2021). In the original version of the paper S. K. Yi's affiliation was incorrectly listed as 'School of Physics, Korea Institute for Advanced Study (KIAS), 85 Hoegiro, Dongdaemun-gu, Seoul 02455, Republic of Korea', whereas the correct affiliation is 'Department of Astronomy and Yonsei University Observatory, Yonsei University, Seoul 03722, Republic of Korea'. In addition S. K. Yi would also like to add the following acknowledgement: SKY acknowledges support from the Korean National Research Foundation (NRF-2020R1A2C3003769). The supercomputing time for numerical simulation was kindly provided by KISTI (KSC-2017-G2-003), and large data transfer was supported by KREONET.