Suchergebnisse

We present kinematic orientations and high-resolution (150 pc) rotation curves for 67 main-sequence star-forming galaxies surveyed in CO (2-1) emission by PHANGS-ALMA. Our measurements are based on the application of a new fitting method tailored to CO velocity fields. Our approach identifies an optimal global orientation as a way to reduce the impact of nonaxisymmetric (bar and spiral) features and the uneven spatial sampling characteristic of CO emission in the inner regions of nearby galaxies. The method performs especially well when applied to the large number of independent lines of sight contained in the PHANGS CO velocity fields mapped at 1 '' resolution. The high-resolution rotation curves fitted to these data are sensitive probes of mass distribution in the inner regions of these galaxies. We use the inner slope as well as the amplitude of our fitted rotation curves to demonstrate that CO is a reliable global dynamical mass tracer. From the consistency between photometric orientations from the literature and kinematic orientations determined with our method, we infer that the shapes of stellar disks in the mass range of log(M-star (M-circle dot)) = 9.0-10.9 probed by our sample are very close to circular and have uniform thickness. ; European Research Council (ERC) 694343 Natural Sciences and Engineering Research Council of Canada RGPIN-201703987 German Research Foundation (DFG) KR4801/1-1 German Research Foundation (DFG) KR4801/2-1 European Research Council (ERC) 714907 German Research Foundation (DFG) SFB 881 138713538 EXC 2181/1-390900948 Programme National "Physique et Chimie du Milieu Interstellaire" (PCMI) of CNRS/INSU INC/INP - CEA Centre National D'etudes Spatiales Programme National Cosmology and Galaxies (PNCG) of CNRS/INSU INP IN2P3 French Atomic Energy Commission European Union's Horizon 2020 research and innovation program 726384

Statistical analysis of velocity fluctuations in the interstellar medium (ISM) of the Milky Way and NGC 4321 show that the motion of molecular gas over scales ranging from 0.1 to 1,000 pc is similar, and consistent with that generated by a combination of gravity and turbulence. ISM structure at one scale is therefore linked to structure at other scales. The density structure of the interstellar medium determines where stars form and release energy, momentum and heavy elements, driving galaxy evolution(1-4). Density variations are seeded and amplified by gas motion, but the exact nature of this motion is unknown across spatial scales and galactic environments(5). Although dense star-forming gas probably emerges from a combination of instabilities(6,7), convergent flows(8)and turbulence(9), establishing the precise origin is challenging because it requires gas motion to be quantified over many orders of magnitude in spatial scale. Here we measure(10-12)the motion of molecular gas in the Milky Way and in nearby galaxy NGC 4321, assembling observations that span a spatial dynamic range 10(-1)-10(3) pc. We detect ubiquitous velocity fluctuations across all spatial scales and galactic environments. Statistical analysis of these fluctuations indicates how star-forming gas is assembled. We discover oscillatory gas flows with wavelengths ranging from 0.3-400 pc. These flows are coupled to regularly spaced density enhancements that probably form via gravitational instabilities(13,14). We also identify stochastic and scale-free velocity and density fluctuations, consistent with the structure generated in turbulent flows(9). Our results demonstrate that the structure of the interstellar medium cannot be considered in isolation. Instead, its formation and evolution are controlled by nested, interdependent flows of matter covering many orders of magnitude in spatial scale. ; German Research Foundation (DFG) KR4801/1-1 KR4801/2-1 European Research Council (ERC) 714907 European Union's Horizon 2020 research and innovation program 639459 National Science Foundation (NSF) 1615105 1615109 1653300 NASA under ADAP NNX16AF48G NNX17AF39G Natural Sciences and Engineering Research Council of Canada RGPIN-2017-03987 National Science Foundation (NSF) 1816715 AST-9800334 AST-0098562 AST-0100793 AST-0228993 AST-0507657 German Research Foundation (DFG) SFB 881 Heidelberg Cluster of Excellence STRUCTURES of Germany's Excellence Strategy EXC-2181/1-390900948 ERC under the European Union's Horizon 2020 research and innovation programme 694343 European Union's Horizon 2020 research and innovation programme 726384 Programme National 'Physique et Chimie du Milieu Interstellaire' (PCMI) of CNRS/INSU INC/INP French Atomic Energy Commission Centre National D'etudes Spatiales Australian Government Australian Research Council UNSW, Sydney Monash Universities Commonwealth Scientific & Industrial Research Organisation (CSIRO)

The PHANGS program is building the first data set to enable the multiphase, multiscale study of star formation across the nearby spiral galaxy population. This effort is enabled by large survey programs with the Atacama Large Millimeter/submillimeter Array (ALMA), MUSE on the Very Large Telescope, and the Hubble Space Telescope (HST), with which we have obtained CO(2–1) imaging, optical spectroscopic mapping, and high-resolution UV– optical imaging, respectively. Here, we present PHANGS-HST, which has obtained NUV–U–B–V–I imaging of the disks of 38 spiral galaxies at distances of 4–23 Mpc, and parallel V- and I-band imaging of their halos, to provide a census of tens of thousands of compact star clusters and multiscale stellar associations. The combination of HST, ALMA, and VLT/MUSE observations will yield an unprecedented joint catalog of the observed and physical properties of ∼100,000 star clusters, associations, H II regions, and molecular clouds. With these basic units of star formation, PHANGS will systematically chart the evolutionary cycling between gas and stars across a diversity of galactic environments found in nearby galaxies. We discuss the design of the PHANGS-HST survey and provide an overview of the HST data processing pipeline and first results. We highlight new methods for selecting star cluster candidates, morphological classification of candidates with convolutional neural networks, and identification of stellar associations over a range of physical scales with a watershed algorithm. We describe the cross-observatory imaging, catalogs, and software products to be released. The PHANGS high-level science products will seed a broad range of investigations, in particular, the study of embedded stellar populations and dust with the James Webb Space Telescope, for which a PHANGS Cycle 1 Treasury program to obtain eight-band 2–21 μm imaging has been approved. ; National Aeronautics & Space Administration (NASA) NAS 5-26555 Aparece en contenido como:NASA 15654 German Research Foundation (DFG) KR4801/1-1 KR4801/2-1 European Research Council (ERC) 714907 Aparece en contenido como:European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program via the ERC Starting Grant MUSTANG 726384/Empire 694343 Aparece en contenido como:European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program German Research Foundation (DFG) SFB 881 138713538 Aparece en contenido como:DFG via the collaborative research center Heidelberg Cluster of Excellence STRUCTURES EXC-2181/1-390900948 ERC via the ERC Synergy Grant ECOGAL 855130 German Research Foundation (DFG) SFB 881 138713538 KR4598/2-1 Natural Sciences and Engineering Research Council of Canada (NSERC) RGPIN-2017-03987 ; Versión publicada - versión final del editor