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arXiv · 1903.06962

Evolution of the Gas Mass Fraction of Progenitors to Today's Massive Galaxies: ALMA Observations in the CANDELS GOODS-S Field

Tommy Wiklind·Henry C. Ferguson·Yicheng Guo·David C. Koo·Dale Kocevski·Bahram Mobasher·Gabriel B. Brammer·Susan Kassin·Anton M. Koekemoer·Mauro Giavalisco·Casey Papovich·Swara Ravindranath·Sandra M. Faber·Jonathan Freundlich·Duilia F. de Mello
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Abstract

We present an ALMA survey of dust continuum emission in a sample of 70 galaxies in the redshift range z=2-5 selected from the CANDELS GOODS-S field. Multi-Epoch Abundance Matching (MEAM) is used to define potential progenitors of a z = 0 galaxy of stellar mass 1.5 10^11 M_sun. Gas masses are derived from the 850um luminosity. Ancillary data from the CANDELS GOODS-S survey are used to derive the gas mass fractions. The results at z<=3 are mostly in accord with expectations: The detection rates are 75% for the z=2 redshift bin, 50% for the z=3 bin and 0% for z>=4. The average gas mass fraction for the detected z=2 galaxies is f_gas = 0.55+/-0.12 and f_gas = 0.62+/-0.15 for the z=3 sample. This agrees with expectations for galaxies on the star-forming main sequence, and shows that gas fractions have decreased at a roughly constant rate from z=3 to z=0. Stacked images of the galaxies not detected with ALMA give upper limits to f_gas of <0.08 and <0.15, for the z=2 and z=3 redshift bins. None of our galaxies in the z=4 and z=5 sample are detected and the upper limit from stacked images, corrected for low metallicity, is f_gas<0.66. We do not think that lower gas-phase metallicities can entirely explain the lower dust luminosities. We briefly consider the possibility of accretion of very low-metallicity gas to explain the absence of detectable dust emission in our galaxies at z>4.

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Tommy Wiklind, Henry C. Ferguson, Yicheng Guo, David C. Koo, Dale Kocevski, Bahram Mobasher, Gabriel B. Brammer, Susan Kassin, Anton M. Koekemoer, Mauro Giavalisco, Casey Papovich, Swara Ravindranath, Sandra M. Faber, Jonathan Freundlich, Duilia F. de Mello. 2019-03-16. Evolution of the Gas Mass Fraction of Progenitors to Today's Massive Galaxies: ALMA Observations in the CANDELS GOODS-S Field. https://doi.org/10.3847/1538-4357/ab1089

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