Lunch talk on May. 25th, 2018

WISDOM Project – Giant Molecular Clouds in the boxy lenticular NGC4429

Speaker:柳莉杰（牛津大学）/ Lijie Liu(University of Oxford)

Venue:Gewu 4410

Time:12:30 PM, Friday, 25th May, 2018

Abstract:We present results on the properties of giant molecular clouds (GMCs)in the central parts of galaxies across the Hubble sequence. Thesewere derived from high angular resolution CO observations with ALMA aspart of the WISDOM project. We focus here on one early-type diskgalaxies with large bulges NGC4429 as an example of our study, with data at aspatial resolution of 0.15” (or 20 pc) and a spectral resolution of2 km/s, sufficient to accurately measure the sizes andvelocity dispersions of most GMCs in the galaxy. The observed GMCsshare basic properties with those of the Milky Way, with similar massand size ranges, but there are also significant differences,suggesting that GMC properties are not universal. In particular, thereseems to be genuine variations in the average mass surface density ofthe GMC populations, the cloud mass distributions vary acrossdifferent galaxy environments, and the size-line width relationsdeviate strongly from that in the Milky Way, in a manner that may becaused by strong shear. We find the clouds in NGC4429 experience strongtidal tearing due to the shear in the plane of the galaxy. The influence of the externalgravity on the total gravitational budget of the clouds is significant (up to80% - 100%). Overall, due to the effect of external gravity, the cloud in NGC4429are no longer Virialised, by only marginally self-gravitating.

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