Browsing by Author "Baker, Andrew J"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    An∼600 pc View of the Strongly Lensed, Massive Main-sequence Galaxy J0901: A Baryon-dominated, Thick Turbulent Rotating Disk with a Clumpy Cold Gas Ring at z=2.259
    (Institute of Physics, 2023) Liu, Daizhong; Förster Schreiber, N M; Genzel, R; Baker, Andrew J
    We present a high-resolution kinematic study of the massive main-sequence star-forming galaxy (SFG) SDSS J090122.37+181432.3 (J0901) at z = 2.259, using ∼0 36 Atacama Large Millimeter/submillimeter Array CO(3–2) and ∼0 1–0 5 SINFONI/VLT Hα observations. J0901 is a rare, strongly lensed but otherwise normal massive (log(M M) ~ 11) main-sequence SFG, offering a unique opportunity to study a typical massive SFG under the microscope of lensing. Through forward dynamical modeling incorporating lensing deflection, we fit the CO and Hα kinematics in the image plane out to about one disk effective radius (Re ∼ 4 kpc) at an ∼600 pc delensed physical resolution along the kinematic major axis. Our results show high intrinsic dispersions of the cold molecular and warm ionized gas (σ0,mol. ∼ 40 km s−1 and σ0,ion. ∼ 66 km s−1) that remain constant out to Re; a moderately low dark matter fraction ( fDM ∼ 0.3–0.4) within Re; and a centrally peaked Toomre Q parameter— agreeing well with the previously established σ0 versus z, fDM versus Σbaryon, and Qʼs radial trends using largesample non-lensed main-sequence SFGs. Our data further reveal a high stellar mass concentration within ∼1–2 kpc with little molecular gas, and a clumpy molecular gas ring-like structure at R ∼ 2–4 kpc, in line with the inside-out quenching scenario. Our further analysis indicates that J0901 had assembled half of its stellar mass only ∼400 Myr before its observed cosmic time, and the cold gas ring and dense central stellar component are consistent with signposts of a recent wet compaction event of a highly turbulent disk found in recent simulations.
  • Thumbnail Image
    Item
    Comparisons between resolved star formation rate and gas tracers in the strongly lensed galaxy sdss j0901+1814 at cosmic noon
    (American Astronomical Society, 2024) Chen, Qingxiang; Baker, Andrew J; Sharon, Chelsea E
    We report new radio observations of SDSSJ090122.37+181432.3, a strongly lensed star-forming galaxy at z =2.26. We image 1.4GHz (L-band) and 3GHz (S-band) continuum using the Very Large Array (VLA) and 1.2 mm (band 6) continuum with Atacama Large Millimeter/submillimeter Array, in addition to the CO(7–6) and CI(3P2→3P1) lines, all at 1 TIR 2.65 0.24 7resolution. Based on the VLA integrated flux densities, we decompose the radio spectrum into its free–free (FF) and nonthermal components. The infrared–radio correlation parameter q 0.31 =+ is consistent with expectations for star-forming galaxies. We obtain radio continuum-derived star formation rates (SFRs) that are free of dust extinction, finding 620+ 280 220 280+ 460 120 M  yr 1 M  yr 1- , 230+ 570 160 M  yr 1- , and- from the FF emission, nonthermal emission, and when accounting for both emission processes, respectively, in agreement with previous results. We estimate the gas mass from the CI(3P2→3P1) line as Mgas = (1.2±0.2)×1011M☉, which is consistent with prior CO(1–0)-derived gas masses. Using our new IR and radio continuum data to map the SFR, we assess the dependence of the Schmidt–Kennicutt relation on choices of SFR and gas tracer for ∼kpc scales. The different SFR tracers yield different slopes, with the IR being the steepest, potentially due to highly obscured star formation in J0901. The radio continuum maps have the lowest slopes and overall fidelity for mapping the SFR, despite producing consistent total SFRs. We also find that the Schmidt-Kennicutt relation slope is flattest when using CO(7–6) or C I(3P2→3P1) to trace gas mass, suggesting that those transitions are not suitable for tracing the bulk molecular gas in galaxies like J0901.