Physical conditions of the interstellar medium in high-redshift lensed submillimeter galaxies (Chentao Yang; European Southern Observatory)

Desde Diciembre 20, 2017 13:15 hasta Diciembre 20, 2017 13:45

En Instituto de Astrofísica, Pontificia Universidad Católica, Vicuña Mackenna 4860, Santiago, Chile

Categorías: Seminarios

Recent wide-area surveys with Herschel, SPT, and other telescopes at submillimeter bands have discovered hundreds of strongly lensed high-redshift (mostly z~2-4) submillimeter galaxies (SMGs), opening new exciting opportunities of follow-up studies of the interstellar medium in these starbursting "monsters" using gas-tracer lines reside in good atmospheric windows. We have thus carefully selected a sample of such lensed SMGs among the brightest sources discovered in the Herschel-ATLAS survey. Using NOEMA, we have conducted the largest studies of the submillimeter H2O lines at high-redshift. The dominance of far-infrared pumping excitation is confirmed for these bright H2O lines, offering a unique diagnostic of both the far-infrared field and the properties of the dense warm molecular gas. H2O+ lines were also detected, shedding light on the chemical processes related to the active star formation. A multi-J CO line survey (J most from 3 up to 8) of the sample has also been conducted with the IRAM-30m telescope. The CO ladders of the high-redshift SMGs, being consist of at least two excitation components, are found to be similar to those of the local star-forming dominated ULIRGs. Using LVG modelling via an MCMC approach, we derive the main properties of the molecular gas (e.g., density and temperature) and discover a tight correlation between gas thermal pressure and star formation efficiency. The detected [CI] lines in our sample are found to be an alternative total molecular gas tracer as well. Finally, using the NOEMA and ALMA high-spatial-resolution images, we are able to study the H2O (for the first time), CO, and dust emission in sub-kpc scale and modelling the kinematics of these high-redshift SMGs.