,
Sub-mm Emission Line Deep Fields: CO and CII Luminosity Functions out to z = 6
(2016)cite arxiv:1602.02761Comment: 19 pages, 11 figures, 3 table, submitted to MNRAS.
Аннотация
Now that ALMA is reaching its full capabilities, observations of sub-mm
emission line deep fields become feasible. Deep fields are ideal to study the
luminosity function of sub-mm emission lines, ultimately tracing the atomic and
molecular gas properties of galaxies. We couple a semi-analytic model of galaxy
formation with a radiative transfer code to make predictions for the luminosity
function of CO J=1-0 up to CO J=6-5 and CII at redshifts z=0-6. We find that:
1) our model correctly reproduces the CO and CII emission of low- and
high-redshift galaxies and reproduces the available constraints on the CO
luminosity function at z<2.75; 2) we find that the CO and CII luminosity
functions of galaxies increase from z = 6 to z = 4, remain relatively constant
till z = 1 and rapidly decrease towards z = 0. The galaxies that are brightest
in CO and CII are found at z~2; 3) the CO J=3-2 emission line is most
favourable to study the CO luminosity and global H2 mass content of galaxies,
because of its brightness and observability with currently available sub-mm and
radio instruments; 4) the luminosity functions of high-J CO lines show stronger
evolution than the luminosity functions of low-J CO lines; 5) our model barely
reproduces the available constraints on the CO and CII luminosity function of
galaxies at z>1.5 and the CO luminosity of individual galaxies at intermediate
redshifts. We argue that this is driven by a lack of cold gas in galaxies at
intermediate redshifts as predicted by cosmological simulations of galaxy
formation. This may lay at the root of other problems theoretical models face
at the same redshifts.
