The 13th Edition of the Marseille Cosmology Conference Series
8-12 Jul 2019 Marseille (France)
Direct detection of the circumgalactic medium using Dragonfly
Deborah Lokhorst  1@  , Roberto Abraham  1@  , Pieter Van Dokkum  2@  
1 : University of Toronto, Department of Astronomy & Astrophysics
2 : Yale, Department of Astronomy

We describe a new approach to studying the intergalactic and circumgalactic medium in the local Universe: direct imaging. We have modified the Dragonfly Telephoto Array to turn it into an ultra-sensitive line emission mapper. This upgrade is designed to target the extremely low surface brightness visible-wavelength line emission from gas in the cosmic web. Using hydrodynamical cosmological simulations (EAGLE) we investigate the expected brightness of this emission at low redshift (z < 0.2) and find that H-alpha emission in extended halos of galaxies (analogous to the extended Lyα halos/blobs detected around galaxies at high redshifts) and the fluorescent ‘skin' of local ‘dark' HI clouds could be directly imaged in exposure times of ~10 hours. We will present first results from our prototype and speculate on the ultimate limits of an upgraded array.


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