Resolved star formation and molecular gas properties of green valley galaxies: a first look with ALMA and MaNGA
2017
We study the role of cold gas in quenching
star formationin the green valley by analysing ALMA $^{12}$CO (1-0) observations of three galaxies with resolved optical spectroscopy from the MaNGA survey. We present resolution-matched maps of the
star formationrate and molecular gas mass. These data are used to calculate the
star formationefficiency (SFE) and gas fraction ($f_{\rm~gas}$) for these galaxies separately in the central `
bulge' regions and outer disks. We find that, for the two galaxies whose global specific
star formationrate (sSFR) deviates most from the
star formationmain sequence, the gas fraction in the
bulgesis significantly lower than that in their disks, supporting an `inside-out' model of galaxy quenching. For the two galaxies where SFE can be reliably determined in the central regions, the
bulgesand disks share similar SFEs. This suggests that a decline in $f_{\rm~gas}$ is the main driver of lowered sSFR in
bulgescompared to disks in green valley galaxies. Within the disks, there exist common correlations between the sSFR and SFE and between sSFR and $f_{\rm~gas}$ on kpc scales -- the local SFE or $f_{\rm~gas}$ in the disks declines with local sSFR. Our results support a picture in which the sSFR in
bulgesis primarily controlled by $f_{\rm~gas}$, whereas both SFE and $f_{\rm~gas}$ play a role in lowering the sSFR in disks. A larger sample is required to confirm if the trend established in this work is representative of green valley as a whole.
-
Correction
-
Cite
-
Save
0
References
0
Citations
NaN
KQI