Instituto de Física y Astronomía

y Centro de Astrofísica de Valparaíso

Calendario de eventos

Título: Physical conditions of the interstellar medium in high-redshift lensed submillimeter galaxies

Jueves, 18. Enero 2018, 15:30
Accesos : 423

Charlista: Chentao Yang

Institución: ESO


Abstract: Recent wide-area surveys with Herschel, SPT, and Planck 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 maximum starbursts 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 modeling via an MCMC approach, we derive the main properties of the molecular gas (e.g., density, temperature, and column density) and discover a tight correlation between gas thermal pressure and star formation efficiency. The detected atomic carbon 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 modeling the kinematics of these high-redshift SMGs.