The Universe's most extreme star-forming galaxies

Caitlin Casey
University of Texas, Austin
Tuesday, April 4, 2017
4:00 pm
NS2 1201


Dusty star-forming galaxies host the most intense stellar nurseries in the Universe.  Their unusual characteristics (SFRs=200-2000Msun/yr) pose a unique challenge for cosmological simulations and galaxy formation theory, particularly at early times.  Although rare today, they were factors of 1000 times more prevalent at z~2-5, contributing significantly to the buildup of the Universe's stellar mass and the formation of high-mass galaxies. However, an ongoing debate lingers as to their evolutionary origins at high-redshift, whether or not they are triggered by major mergers of gas-rich disk galaxies, or if they are solitary galaxies continually fed pristine gas from the intergalactic medium.  Observational evidence has been mixed over recent years; some studies clearly point to chaotic kinematic histories and fast gas depletion times (~<100Myr), while other work may demonstrate secular (though active) disks can sustain high star-formation rates over long periods of time.  Similarly, some works argue such extreme star-formers contribute very little to cosmic star-formation, while others find quite the opposite.  Furthermore, their presence in early protoclusters, only revealed quite recently, pose intriguing questions regarding the collapse of large scale structure.  I will discuss some of the latest observational programs dedicated to understanding their origins and prevalence at early times, their context in the cosmic web, and future long-term observing campaigns that will reveal their relationship to `normal’ galaxies, thus teaching us valuable lessons on the physical mechanisms of galaxy growth and the collapse of large scale structure in an evolving Universe.


Michael Cooper