In this paper we study the causes of the reported mass-dependence of the
slope of SFR-M* relation, the so-called "Main Sequence" of star-forming
galaxies, and discuss its implication on the physical processes that shaped the
star formation history of massive galaxies over cosmic time. We make use of the
near-infrared high-resolution imaging from the Hubble Space Telescope in the
CANDELS fields to perform a careful bulge-to-disk decomposition of distant
galaxies and measure for the first time the slope of the SFR-Mdisk relation at
z=1. We find that this relation follows very closely the shape of the nominal
SFR-M* correlation, still with a pronounced flattening at the high-mass end.
This is clearly excluding, at least at z=1, the secular growth of quiescent
stellar bulges in star-forming galaxies as the main driver for the change of
slope of the Main Sequence. Then, by stacking the Herschel data available in
the CANDELS field, we estimate the gas mass (Mgas) and the star formation
efficiency (SFE=SFR/Mgas) at different positions on the SFR-M* relation. We
find that the relatively low SFRs observed in massive galaxies (M* > 5x10^10
Msun) are caused by a decreased star formation efficiency, by up to a factor of
3 as compared to lower stellar mass galaxies, and not by a reduced gas content.
We argue that this stellar-mass-dependent SFE can explain the varying slope of
the Main Sequence since z=1.5, hence over 70% of the Hubble time. The drop of
SFE occurs at lower masses in the local Universe (M* > 2x10^10 Msun) and is not
present at z=2. Altogether this provides evidence for a slow downfall of the
star formation efficiency in massive Main Sequence galaxies. The resulting loss
of star formation is found to be rising starting from z=2 to reach a level
comparable to the mass growth of the quiescent population by z=1. We finally
discuss the possible physical origin of this phenomenon.
Description
[1601.04226] Observational evidence of a slow downfall of star formation efficiency in massive galaxies during the last 10 Gyr
%0 Generic
%1 schreiber2016observational
%A Schreiber, Corentin
%A Elbaz, David
%A Pannella, Maurilio
%A Ciesla, Laure
%A Wang, Tao
%A Koekemoer, Anton M.
%A Rafelski, Marc
%A Daddi, Emanuele
%D 2016
%K evolution formation galaxy massive star
%T Observational evidence of a slow downfall of star formation efficiency
in massive galaxies during the last 10 Gyr
%U http://arxiv.org/abs/1601.04226
%X In this paper we study the causes of the reported mass-dependence of the
slope of SFR-M* relation, the so-called "Main Sequence" of star-forming
galaxies, and discuss its implication on the physical processes that shaped the
star formation history of massive galaxies over cosmic time. We make use of the
near-infrared high-resolution imaging from the Hubble Space Telescope in the
CANDELS fields to perform a careful bulge-to-disk decomposition of distant
galaxies and measure for the first time the slope of the SFR-Mdisk relation at
z=1. We find that this relation follows very closely the shape of the nominal
SFR-M* correlation, still with a pronounced flattening at the high-mass end.
This is clearly excluding, at least at z=1, the secular growth of quiescent
stellar bulges in star-forming galaxies as the main driver for the change of
slope of the Main Sequence. Then, by stacking the Herschel data available in
the CANDELS field, we estimate the gas mass (Mgas) and the star formation
efficiency (SFE=SFR/Mgas) at different positions on the SFR-M* relation. We
find that the relatively low SFRs observed in massive galaxies (M* > 5x10^10
Msun) are caused by a decreased star formation efficiency, by up to a factor of
3 as compared to lower stellar mass galaxies, and not by a reduced gas content.
We argue that this stellar-mass-dependent SFE can explain the varying slope of
the Main Sequence since z=1.5, hence over 70% of the Hubble time. The drop of
SFE occurs at lower masses in the local Universe (M* > 2x10^10 Msun) and is not
present at z=2. Altogether this provides evidence for a slow downfall of the
star formation efficiency in massive Main Sequence galaxies. The resulting loss
of star formation is found to be rising starting from z=2 to reach a level
comparable to the mass growth of the quiescent population by z=1. We finally
discuss the possible physical origin of this phenomenon.
@misc{schreiber2016observational,
abstract = {In this paper we study the causes of the reported mass-dependence of the
slope of SFR-M* relation, the so-called "Main Sequence" of star-forming
galaxies, and discuss its implication on the physical processes that shaped the
star formation history of massive galaxies over cosmic time. We make use of the
near-infrared high-resolution imaging from the Hubble Space Telescope in the
CANDELS fields to perform a careful bulge-to-disk decomposition of distant
galaxies and measure for the first time the slope of the SFR-Mdisk relation at
z=1. We find that this relation follows very closely the shape of the nominal
SFR-M* correlation, still with a pronounced flattening at the high-mass end.
This is clearly excluding, at least at z=1, the secular growth of quiescent
stellar bulges in star-forming galaxies as the main driver for the change of
slope of the Main Sequence. Then, by stacking the Herschel data available in
the CANDELS field, we estimate the gas mass (Mgas) and the star formation
efficiency (SFE=SFR/Mgas) at different positions on the SFR-M* relation. We
find that the relatively low SFRs observed in massive galaxies (M* > 5x10^10
Msun) are caused by a decreased star formation efficiency, by up to a factor of
3 as compared to lower stellar mass galaxies, and not by a reduced gas content.
We argue that this stellar-mass-dependent SFE can explain the varying slope of
the Main Sequence since z=1.5, hence over 70% of the Hubble time. The drop of
SFE occurs at lower masses in the local Universe (M* > 2x10^10 Msun) and is not
present at z=2. Altogether this provides evidence for a slow downfall of the
star formation efficiency in massive Main Sequence galaxies. The resulting loss
of star formation is found to be rising starting from z=2 to reach a level
comparable to the mass growth of the quiescent population by z=1. We finally
discuss the possible physical origin of this phenomenon.},
added-at = {2016-01-19T10:36:34.000+0100},
author = {Schreiber, Corentin and Elbaz, David and Pannella, Maurilio and Ciesla, Laure and Wang, Tao and Koekemoer, Anton M. and Rafelski, Marc and Daddi, Emanuele},
biburl = {https://www.bibsonomy.org/bibtex/29b60dcd05159c5e944b1000ff91a9508/miki},
description = {[1601.04226] Observational evidence of a slow downfall of star formation efficiency in massive galaxies during the last 10 Gyr},
interhash = {776086312ccc32815d2038166880d12d},
intrahash = {9b60dcd05159c5e944b1000ff91a9508},
keywords = {evolution formation galaxy massive star},
note = {cite arxiv:1601.04226Comment: 21 pages, 15 figures, submitted for publication in A&A},
timestamp = {2016-01-19T10:36:34.000+0100},
title = {Observational evidence of a slow downfall of star formation efficiency
in massive galaxies during the last 10 Gyr},
url = {http://arxiv.org/abs/1601.04226},
year = 2016
}