Thursday

Molecular clouds are formed and shaped as a result of the interchange and evolution of gas through a wide range of densities and scales. Understanding the hierarchical organisation of the molecular component of the interstellar medium and the journey of the molecular gas through the galaxy, is therefore essential to pin down the global processes that regulate star formation on a galactic scale. One particularly striking type of clouds thought to be tightly linked to the larger motions and scales of spiral galaxies, are the so-called giant molecular filaments, which are extremely elongated giant molecular clouds (GMCs), some reaching more than 100pc in length, as observed in both the Milky Way and nearby spiral galaxies. It is not clear, however, if these extreme clouds trace any particular region in spiral galaxies and/or if they represent an important step on the evolution of molecular clouds. Here I will present our recent work trying to grasp some of these issues by studying the population of GMCs from a simulation of a portion of a spiral galaxy, and explore how different galactic environments can affect the observable properties of GMCs, namely by following the clouds as they travel from the shear-dominated inter-arm regions into and through spiral arms, giving particular focus on the formation and evolution of giant molecular filaments.