J/A+A/633/A9 Synthetic photometry as a function of redshift (Martins+, 2020)
Spectral properties and detectability of supermassive stars in protoglobular
clusters at high redshift.
Martins F., Schaerer D., Haemmerle L., Charbonnel C.
<Astron. Astrophys. 633, A9 (2020)>
=2020A&A...633A...9M 2020A&A...633A...9M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Redshifts ; Photometry, HST ; Models
Keywords: stars: massive - globular clusters: general
Abstract:
We investigate the spectral properties of proto-GCs that would host a
supermassive star (SMS). Our main goal is to quantify how such a star
would affect the integrated light of the cluster, and to study the
detectability of such objects. We computed nonlocal thermal
equilibrium atmosphere models for SMS with various combinations of
stellar parameters (luminosity, effective temperature, and mass) and
metallicities appropriate for GCs, and we predict their emergent
spectra. Using these spectra, we calculated the total emission of
young proto-GCs with SMS as predicted in a previously reported
scenario, and we computed synthetic photometry in UV, optical, and
near-IR bands, in particular for the James Webb Space Telescope
(JWST). At an effective temperature of 10000K, the spectrum of SMSs
shows a Balmer break in emission. This feature is due to strong
nonlocal thermal equilibrium effects (implied by the high luminosity)
and is not observed in "normal" stars. The hydrogen lines also show a
peculiar behavior, with Balmer lines in emission while higher series
lines are in absorption. At 7000 K, the Balmer break shows a strong
absorption. At high effective temperatures, the Lyman break is found
in emission. Cool and luminous SMSs are found to dominate the
integrated spectrum of the cluster, except for the UV range. The
predicted magnitudes of these proto-GCs are magAB∼28-30 between 0.7
and 8um and for redshifts z∼4-10, which is detectable with the JWST.
The peculiar observational features of cool SMSs imply that they might
in principle be detected in color-color diagrams that probe the
spectral energy distribution below and above the Balmer break.
Description:
The catalogue contains synthetic photometry for proto globular
clusters that would host a supermassive star (SMS) as a function of
redshift, computed for some of the main filters of the NIRCam and MIRI
instruments on the JWST. The photometry is given for 3 SMS models (A2,
A4, B3) excluding possible nebular emission, the cluster SED with
parameters described in Table 3 (both including and excluding nebular
emission), and for the total spectrum of SMS + cluster, including
nebular emission.
The synthetic photometry in AB magnitudes for redshifts from z=0 to 10
in steps of 0.1 is computed assuming standard cosmological parameters:
H0=70km/s/Mpc, {OMEGA}{LAMBDA}=0.7, and {OMEGA}m=0.3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tabled1.dat 118 101 SMS Model A2, without nebular emission
tabled2.dat 118 101 Total spectrum, SMS Model A2 + stellar cluster,
with nebular emission
tabled3.dat 118 101 SMS Model A4, without nebular emission
tabled4.dat 118 101 Total spectrum, SMS Model A4 + stellar cluster,
with nebular emission
tabled5.dat 118 101 SMS Model B3, without nebular emission
tabled6.dat 118 101 Total spectrum, SMS Model B3 + stellar cluster,
with nebular emission
tabled7.dat 118 101 Cluster model, without nebular emission
tabled8.dat 118 101 Cluster model, with nebular emission
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Byte-by-byte Description of file: tabled?.dat
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Bytes Format Units Label Explanations
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2- 8 F7.4 --- z Redshift
9- 18 E10.3 mag F070W F070W NIRCAM filter magnitude (AB)
19- 28 E10.3 mag F090W F090W NIRCAM filter magnitude (AB)
29- 38 E10.3 mag F115W F115W NIRCAM filter magnitude (AB)
39- 48 E10.3 mag F150W F150W NIRCAM filter magnitude (AB)
49- 58 E10.3 mag F200W F200W NIRCAM filter magnitude (AB)
59- 68 E10.3 mag F277W F277W NIRCAM filter magnitude (AB)
69- 78 E10.3 mag F356W F356W NIRCAM filter magnitude (AB)
79- 88 E10.3 mag F410W F410W NIRCAM filter magnitude (AB)
89- 98 E10.3 mag F444W F444W NIRCAM filter magnitude (AB)
99-108 E10.3 mag F560W F560W MIRI filter magnitude (AB)
109-118 E10.3 mag F770W F770W MIRI filter magnitude (AB)
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Acknowledgements:
Fabrice Martins, fabrice.martins(at)univ-montp2.fr
(End) Patricia Vannier [CDS] 05-Dec-2019