HOME 커뮤니티 천문학회오픈콜로퀴움
|저자 : 한국천문학회||등록일시 : 2022-08-08 11:47:39|
Speaker: Fabian Walter, Eva Schinnerer (Max Planck Institute for Astronomy)
Location: Jang Yeong-Sil Hall 331-2 & Zoom
Time: 8/16 (Tue) 11:00 - 12:15
Host: Yujin Yang
1st talk (30min)
A cloud-scale view on cloud and star formation from PHANGS (Eva Schinnerer, MPIA)
Where do stars form and how is their formation regulated across galactic disks are two critical questions for our understanding of the star formation process. High angular observations of nearby galaxies allow us to sample the star formation process across entire galactic disks reaching now regularly the scales of the star-forming units, namely Giant Molecular Clouds (GMCs) and HII regions. Such data provide new insights on the molecular gas reservoir and its role in the star formation process as well as information on the importance of galactic components such as bulges, stellar bars, spiral arms and active galactic nuclei (AGN) in the conversion of cold (molecular) gas into stars. The PHANGS (Physics at High Angular resolution in Nearby GalaxieS) survey combines cloud-scale observations of molecular gas from ALMA, HII regions from VLT/MUSE, stellar clusters from HST as well as PAH and hot dust emission from JWST. I will introduce the survey and present a few highlight from the ongoing research of the collaboration.
2nd talk (30min)
ASPECS: The ALMA Spectroscopic Survey in the Hubble Ultra-Deep Field (Fabian Walter, MPIA)
The ALMA Large Program ASPECS (The ALMA SPECtral line Survey in the UDF) set out to measure the dust and molecular gas content in distant galaxies in the best-studied cosmological deep field, the Hubble Ultra-Deep Field (UDF). Through a unique observing technique, the survey resulted in a full census of gas-rich galaxies in the UDF, yielding dozens of detections in dust continuum and molecular gas emission. Their physical properties (stellar mass, star formation rate, etc.) could be accurately constrained thanks to the unparalleled wealth of ancillary data, inclduding most sensitive HST and VLT/MUSE observations. We confirm that, on average, the gas mass fractions of distant galaxies decreased by an order of magnitude since redshift 2, and that the gas depletion times are ~1 Gyr, in approximate agreement with the local value. The ASPECS deep band 6 continuum map of the field shows that more than 90% of the dust continuum emission in the field has been resolved in individual galaxies. The total CO emission in this well-defined cosmological volume is used to constrain the evolution of the cosmic molecular gas density. Together with previous measurements of the cosmic evolution of the stellar mass density, the star formation rate density, and the atomic gas density, these measurements provide a quantitative measurement of gas accretion on the central disks of galaxies.
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