Tuesday

The bar instability in disk galaxies is well known, but it remains unclear why some disks have bars and others do not, and what exactly is the role of bars on the evolution of their host galaxy. One of the early discoveries in Galaxy Zoo was that bars were more common in red spirals than star forming spirals (Masters et al. 2010), leading us to question what role they played in processes which quench star formation in spiral galaxies.

Crowdsourced visual classifications from Galaxy Zoo have been demonstrated to provide a reliable way to identify bars in both nearby galaxies (Willett et al 2014) and those out to high redshift (Willett et al. 2016, Simmons et al. 2016). These samples have been used to study the role of the bar instability in disc galaxy formation in a series of papers led by a variety of members of the Galaxy Zoo science team (e.g. Hoyle et al. 2011, Masters et al. 2011, 2012, Skibba et al. 2012, Casteels et al. 2013, Cheung et al. 2014, Melvin et al. 2014, Simmons et al. 2014, Galloway et al. 2015, Smethurst et al. in press, Kruk et al. submitted). In this talk I will review results from these works, which are collectively providing a picture of bars as an important evolutionary driver of their host disc galaxy, and provide evidence of a potential “bar quenching” mechanism, important in the secular era of galaxy evolution.