What is the Nature of Dark Matter in dwarf galaxies? What roles do AGN, merging, and stellar feedback play in shaping dwarf properties? Can the diversity of dwarf rotation curves be explained by baryonic effects or do they point to an exotic form of Dark Matter?

Merian is an ambitious program designed to answer these questions. Merian will operate from January 2021-2023 and will build the largest and most well-understood existing sample of star forming dwarf galaxies (with stellar masses between 8<log(M*)<9). Merian will use 62 nights on the Blanco telescope in Chile and will image 800 square degrees of the sky in two custom made medium-band filters to create a sample of 100,000 star forming dwarf galaxies (with 90% completeness) in the redshift range 0.058<z<0.10. Merian is unmatched by prior surveys; SDSS is incomplete below log(M*)=9, GAMA reaches log(M*)=8 only at z<0.02, and pencil beam surveys have limited gravitational lensing capabilities to probe the dark matter component. Merian will cover the HSC SSP Wide field which provides gravitational lensing capabilities to probe the dark matter component of dwarfs (Leauthaud et al. 2020).

Team

Co.PIs : Alexie Leauthaud (UCSC) and Jenny Greene (Princeton)

Theory group: Alyson Brooks (Rutgers), Annika Peter (OSU), Arka Banerjee (U. Chicago), Stacy Kim (University of Surrey), Justin Read (University of Surrey) 

Data Collection and Analysis group: Vivienne Baldassare (Washington State), Shany Danieli (IAS), Jim Gunn (Princeton), Robert Lupton (Princeton), Yifei Luo (UCSC), Erin Kado-Fong (UCSC), Song Huang (Tsinghua), Ben Johnston (Harvard), Amy Sardone (OSU), Zheng Cai (Tsinghua), X. Prochaska (UCSC)

Merian honors 17th century Maria Sibylla Merian (1647, 1717), the first female entomologist and naturalist. Her fascination with the world of tiny things combined with unique observational skills led to a number of important discoveries, including the previously unknown metamorphosis of caterpillars into butterflies.