Robust Gas Measurements for BreakBRD Galaxies

The general view of galaxy quenching is that it takes place from the inside-out, explaining the commonality of non-star forming bulges and actively star forming disks across the galaxy population. However, a fraction of apparently quenching galaxies display opposite behavior: actively star forming bulges and non star-forming disks. These galaxies are dubbed BreakBRDs (“Break Bulges in Red Disks”). A physical explanation for their evolution remains unknown, but their ubiquity across mass and environment suggests they may represent a fundamental mode of evolution or have multiple drivers. Existing data hint that breakBRDs have smaller gas reservoirs and shorter gas depletion timescales than the general population, but the depth of these data do not allow us to determine the absolute extent to which breakBRDs are gas poor (and whether there are multiple populations). We propose 306.5 hours of GBT L-band time to obtain deeper HI observations (down to a sensitivity of 0.05 times the stellar mass for each galaxy) of 76 breakBRDs with existing shallow data from the GBT or ALFALFA survey. Adequately sensitive HI measurements will provide a prediction about the future of these galaxies, and identify them as quenching or as ramping up their star formation.

Team Members:

  • David V. Stark (UW)
  • Sarah Tuttle (UW)
  • Stephanie Tonnesen (Simons)

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