GBT13A-276

Tracking Star Formation Efficiency as a Function of Cosmic Structure

Abstract

Our recent work suggests that long-term specific star formation rate SSFR_LT, as traced by U-NIR color which averages star formation over hundreds of Myrs, closely tracks *current* gas/stellar mass ratios, G/S.
This cause-effect conundrum is naturally explained if accretion rates are
fairly constant on Gyr timescales. However, if accretion intensifies when
cosmic structures (e.g., filaments, walls) condense, this constancy may
vary with environment. Results from our previous program, GBT11B-056,
hint at such an enhancement of G/S at fixed SSFR within a cosmic wall,
based on just 132 galaxies. To confirm and extend these results we
request 191.2hr of GBT time to complete 21 cm coverage for 127 more
galaxies in a second subvolume of the RESOLVE Survey, which comprises all
~1600 galaxies above baryonic mass ~10^9 Msun in a 53,000 cubic Mpc
volume of the local universe. The new GBT data will supplement
flux-limited ALFALFA Survey coverage, ensuring detections or strong upper
limits (<5% of stellar mass) for most galaxies. Besides testing how the
G/S vs. SSFR_LT relation depends on environment, these data will lay the
groundwork for future ALMA studies and be immediately public.

Investigators

Name	Institution
David Stark *	Space Telescope Science Institute; Haverford College
Erik Hoversten	North Carolina, University of
Andreas Berlind	Vanderbilt University
Amanda Moffett	North Carolina, University of
D.J. Pisano	Cape Town, University of
Kathleen Eckert	North Carolina, University of; Pennsylvania, University of
Lisa Wei	Harvard-Smithsonian Center for Astrophysics
Sheila Kannappan	North Carolina, University of
Nelson Padilla	Pontificia Universidad Católica de Chile
Ashley Baker	North Carolina, University of
GBT Operator	Green Bank Observatory
Kirsten Hall	North Carolina, University of; Center for Astrophysics | Harvard & Smithsonian; Johns Hopkins University
Linda Watson	European Southern Observatory

* indicates the PI