Description:

From Observations to Origins: Disentangling Gas Flows in the Circumgalactic Medium

Zach Hafen, Northwestern Astronomy PhD Student

As much as half of the gas mass in our galaxy's dark matter halo may reside not in the galaxy itself, but in the surrounding area, the circumgalactic medium (CGM). The vast gas content of the CGM, loosely defined as the volume immediately outside the galaxy but inside the dark matter halo, can be broadly classified as originating either in accretion from the intergalactic medium (IGM) or winds from galaxies. Both of these are crucial to the process of galaxy formation: IGM accretion provides the material necessary for observed star formation rates, while galactic winds are linked closely to the regulation of star formation through feedback. Despite their individual importance, differentiating these gas flows in observations is an outstanding problem in studies of the CGM. I will discuss our efforts to address this problem through the use of hydrodynamic galaxy formation simulations.

Progress with Dark Matter Search Bubble Chambers

Matt Bressler, Drexel Physics PhD Student at Fermi National Laboratory

Superheated detectors with fluorocarbon active fluids have been leaders in the direct-detection spin-dependent WIMP search for more than 10 years, achieving strong sensitivity with relatively small target masses, simple detectors, and low backgrounds. We will extend the bubble chamber technique to the low-mass spin-independent WIMP search, using noble elements at high degrees of superheat (lower nuclear-recoil thresholds compared to previous WIMP search bubble chambers) to search for WIMPs with masses in the range 0.7-7 GeV/c^2. I will discuss some of the recent progress in bubble chamber calibration, and present the current status of the  construction of the Scintillating Bubble Chamber (SBC) collaboration’s 10 kg argon bubble chamber.