Collaborative Research: The Emergence of Dusty Starbursts in Cosmic History

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

Recently, a sizable population of galaxies has been discovered in the early universe (z > 6) that are forming stars at a furious rate, i.e., > 1,000 solar masses per year. For comparison, large present-day spirals like the Milky Way form 1-2 solar masses of stars each year. Just as surprising is the fact that these objects are heavily obscured by immense amounts of cosmic dust, requiring observations at very long wavelengths for detections. The very existence of massive starburst galaxies and large amounts of dust at z > 6 pushes our current theory of early star formation to the limit. This collaborative project will conduct a comprehensive survey of a large sample of candidate dusty starbursts (629 objects in total) using the 50-m Large Millimeter Telescope (LMT), now operating at its full capacity, to determine accurate redshifts and positions and define a statistically significant sample of z > 6 objects. Deep optical and near-infrared follow-ups will identify optical counterparts and stellar masses/populations. Together, these will place strong constraints on the star formation and metal enrichment history of the early universe. This work will support a postdoc and a graduate student, public outreach activities, and a program to produce scientifically literate journalists. The overall approach is to observe the "500 micron risers" sample of 629 dusty, high-redshift galaxies using the LMT's Redshift Search Receiver. This wide-bandwidth spectrograph is an ideal instrument to measure redshifts for such objects. The team will combine institutional and open-time access to build a spectroscopic sample of ∼50 objects, of which ∼27 objects should be bona fide dusty starbursts at z > 6. In addition, the LMT/TolTEC instrument will soon carry out public legacy surveys, which will provide deep, 1–2 mm images that cover a significant portion of their fields. These public data will provide millimeter photometry as well as positions accurate to ~1 arcsecond for ∼160 of the objects, which will allow the team to pinpoint their optical to near- infrared counterparts. In the end, they will have the largest spectroscopic sample and the largest counterpart sample for dusty starbursts at z > 6, which they will analyze in a statistical manner. This will help fill in a critical piece that is still missing from the early cosmic star formation and metal enrichment history. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.