TY - JOUR
T1 - GAS FRACTION and DEPLETION TIME of MASSIVE STAR-FORMING GALAXIES at z ∼ 3.2
T2 - NO CHANGE in GLOBAL STAR FORMATION PROCESS OUT to z > 3
AU - Schinnerer, E.
AU - Groves, B.
AU - Sargent, M. T.
AU - Karim, A.
AU - Oesch, P. A.
AU - Magnelli, B.
AU - Lefevre, O.
AU - Tasca, L.
AU - Civano, F.
AU - Cassata, P.
AU - Smolčić, V.
N1 - Publisher Copyright:
© 2016 The American Astronomical Society. All rights reserved.
PY - 2016/12/10
Y1 - 2016/12/10
N2 - The observed evolution of the gas fraction and its associated depletion time in main-sequence (MS) galaxies provides insights on how star formation proceeds over cosmic time. We report ALMA detections of the rest-frame ∼300 μm continuum observed at 240 GHz for 45 massive (〈log(M∗(M⊙))〉, normal star-forming (〈log(sSFR(yr-1))〉=-8.6), i.e., MS, galaxies at Z ≈ 3.2 in the COSMOS field. From an empirical calibration between cold neutral, i.e., molecular and atomic, gas mass and monochromatic (rest-frame) infrared luminosity, the gas mass for this sample is derived. Combined with stellar mass and star formation rate (SFR) estimates (from MagPhys fits) we obtain a median gas fraction of μgas= Mgas/M∗= 1.65-0.19 +0.18and a median gas depletion time tdep1.(gyr)= Mgas/SFR = 0.68-0.08 +0.07correction for the location on the MS will only slightly change the values. The reported uncertainties are the error on the median. Our results are fully consistent with the expected flattening of the redshift evolution from the 2-SFM (2 star formation mode) framework which empirically prescribes the evolution assuming a universal, log-linear relation between SFR and gas mass coupled to the redshift evolution of the specific star formation rate (sSFR) of MS galaxies. While shows only a mild dependence on location within the MS, a clear trend of increasing μgasacross the MS is observed (as known from previous studies). Further, we comment on trends within the MS and (in)consistencies with other studies.
AB - The observed evolution of the gas fraction and its associated depletion time in main-sequence (MS) galaxies provides insights on how star formation proceeds over cosmic time. We report ALMA detections of the rest-frame ∼300 μm continuum observed at 240 GHz for 45 massive (〈log(M∗(M⊙))〉, normal star-forming (〈log(sSFR(yr-1))〉=-8.6), i.e., MS, galaxies at Z ≈ 3.2 in the COSMOS field. From an empirical calibration between cold neutral, i.e., molecular and atomic, gas mass and monochromatic (rest-frame) infrared luminosity, the gas mass for this sample is derived. Combined with stellar mass and star formation rate (SFR) estimates (from MagPhys fits) we obtain a median gas fraction of μgas= Mgas/M∗= 1.65-0.19 +0.18and a median gas depletion time tdep1.(gyr)= Mgas/SFR = 0.68-0.08 +0.07correction for the location on the MS will only slightly change the values. The reported uncertainties are the error on the median. Our results are fully consistent with the expected flattening of the redshift evolution from the 2-SFM (2 star formation mode) framework which empirically prescribes the evolution assuming a universal, log-linear relation between SFR and gas mass coupled to the redshift evolution of the specific star formation rate (sSFR) of MS galaxies. While shows only a mild dependence on location within the MS, a clear trend of increasing μgasacross the MS is observed (as known from previous studies). Further, we comment on trends within the MS and (in)consistencies with other studies.
KW - galaxies: ISM
KW - galaxies: evolution
KW - galaxies: high-redshift
KW - submillimeter: ISM
UR - http://www.scopus.com/inward/record.url?scp=85006381944&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/833/1/112
DO - 10.3847/1538-4357/833/1/112
M3 - Article
SN - 0004-637X
VL - 833
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 112
ER -