J/A+A/609/A130 [CII] luminosities of galaxies in G.A.S.+Cloudy (Lagache+, 2018)
The [CII] 158 micron line emission in high-redshift galaxies.
Lagache G., Cousin M., Chatzikos M.
<Astron. Astrophys. 609, A130 (2018)>
=2018A&A...609A.130L 2018A&A...609A.130L (SIMBAD/NED BibCode)
ADC_Keywords: Models, evolutionary ; Galaxy catalogs ; Interstellar medium
Keywords: galaxies: evolution - galaxies: high-redshift - galaxies: ISM
Abstract:
Gas is a crucial component of galaxies, providing the fuel to form
stars, and it is impossible to understand the evolution of galaxies
without knowing their gas properties. The [CII] fine structure
transition at 158µm is the dominant cooling line of cool
interstellar gas, and is the brightest of emission lines from star
forming galaxies from FIR through meter wavelengths, almost unaffected
by attenuation. With the advent of ALMA and NOEMA, capable of
detecting [CII]-line emission in high-redshift galaxies, there has
been a growing interest in using the [CII] line as a probe of the
physical conditions of the gas in galaxies, and as a star formation
rate (SFR) indicator at z≥4. In this paper, we have used a
semi-analytical model of galaxy evolution (G.A.S.) combined with the
photoionisation code CLOUDY to predict the [CII] luminosity of a large
number of galaxies (25,000 at z~=5) at 4≤z≤8. We assumed
that the [CII]-line emission originates from photo-dominated regions.
At such high redshift, the CMB represents a strong background and we
discuss its effects on the luminosity of the [CII] line. We studied
the L[CII]-SFR and L[CII]-Zg relations and show that they do not
strongly evolve with redshift from z=4 and to z=8. Galaxies with
higher [CII] luminosities tend to have higher metallicities and higher
star formation rates but the correlations are very broad, with a
scatter of about 0.5 and 0.8dex for L[CII]-SFR and L[CII]-Zg,
respectively. Our model reproduces the L[CII]-SFR relations observed
in high-redshift star-forming galaxies, with [CII] luminosities lower
than expected from local L[CII]-SFR relations. Accordingly, the
local observed L[CII]-SFR relation does not apply at high-z (z~=5),
even when CMB effects are ignored. Our model naturally produces the
[CII] deficit (i.e. the decrease of L[CII]/LIR with LIR), which
appears to be strongly correlated with the intensity of the radiation
field in our simulated galaxies. We then predict the [CII] luminosity
function, and show that it has a power law form in the range of L[CII]
probed by the model with a slope α=-1. The slope is not evolving
from z=4 to z=8 but the number density of [CII]-emitters decreases by
a factor of 20x. We discuss our predictions in the context of current
observational estimates on both the differential and cumulative
luminosity functions. The outputs from the model are distributed as
FITS-formatted files at the CDS.
Description:
One fits file per redshift (z=4, 4.7, 5.9, 6.7, 7.6) which gives for
all galaxies with mass above 10^7 Msol:
Log(M_star): stellar mass (Msol)
Log(M_gas): gas mass (Mssol)
ZgOHINDEX: gas metallicity (OH Index)
Zg_MZ: gas metallicity (units of Zsol)
LOG(ISRF): interstellar radiation field (unit of G0)
Log(nHI): HI density (cm-3)
Log(SFR): star formation rate from the model (Msol/yr)
log(SFR_obs): star formation rate computed from the UV and
IR luminosities (Msol/yr)
log(LIR): 8-1000 micron luminosity (Lsol)
Log(LCII): CII luminosity (Lsol)
Log(LCII_WOA): CII luminosity without CMB attenuation (Lsol)
Log(LCIIWOAWOH): CII luminosity without CMB attenuation and heating (Lsol)
Log(LCII_Vallini): CII luminosity using N=2 (Eq. 11) (Lsol)
Log(LAGN): AGN bolometric luminosity (Lsol)
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
gcciiz4.dat 126 10803 Outputs from the model for z=4
gcciiz5.dat 126 6175 Outputs from the model for z=4.7
gcciiz6.dat 126 2374 Outputs from the model for z=5.9
gcciiz7.dat 126 1074 Outputs from the model for z=6.7
gcciiz8.dat 126 388 Outputs from the model for z=7.6
fits/* . 5 All tables in fits format
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Byte-by-byte Description of file: gcciiz?.dat
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Bytes Format Units Label Explanations
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1- 8 F8.5 [Msun] logMstar Stellar mass (logMstar)
10- 17 F8.5 [Msun] logMgas Gas mass (log_Mgas)
19- 26 F8.5 --- ZgOHindex Gaz metallicity in OH index unit
(ZgOHindex)
28- 36 F9.6 Sun ZgmZ Gaz metallicity (Zg_mZ)
38- 44 F7.5 --- logISRF Interstellar radiation field in G0 unit
(log_ISRF)
46- 52 F7.5 [cm-3] lognHI HI density (log_nHI)
54- 62 F9.6 [Msun/yr] logSFR Star formation rate from the model (log_SFR)
64- 72 F9.6 [Msun/yr] logSFRobs Star formation rate computed from the UV and
IR luminosities (logSFRobs)
74- 81 F8.5 [Lsun] logLIR 8-1000 micron luminosity (logLIR)
83- 90 F8.5 [Lsun] logLCII CII luminosity (logLCII)
92- 99 F8.5 [Lsun] logLCIIw CII luminosity without CMB attenuation
(logLCII_woa)
101-108 F8.5 [Lsun] logLCIIww CII luminosity without CMB attenuation and
heating (logLCIIwoawoh)
110-117 F8.5 [Lsun] logLCIIVa CII luminosity using N=2 (Eq. 11)
(logLCII_Vallini)
119-126 F8.6 [Lsun] logLAGN ? AGN bolometric luminosity (logLagn)
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Acknowledgements:
Guilaine Lagache, guilaine.lagache(at)lam.fr
(End) Patricia Vannier [CDS] 07-Nov-2017