Zusammenfassung
We here derive upper limits on the mass and luminosity of Population III
(POPIII) dominated proto-galaxies based on the collapse of primordial gas under
the effect of angular momentum loss via Ly$\alpha$ radiation drag and the gas
accretion onto a galactic centre. Our model predicts that POPIII-dominated
galaxies at z ~ 7 are hosted by haloes with $M_halo 1.5 \times
10^8 - 1.1 10^9 ~M_ødot$, that they have Ly$\alpha$
luminosities of $L_Ly\alpha 3.0 10^42 - 2.1 10^43$
erg/s, stellar mass of $M_star 0.8 10^5 - 2.5 10^6
~M_ødot$, and outflowing gas with velocities $V_out 40$ km/s
due to Ly$\alpha$ radiation pressure. We show that the POPIII galaxy candidate
CR7 violates the derived limits on stellar mass and Ly$\alpha$ luminosity and
thus is unlikely to be a POPIII galaxy. POPIII-dominated galaxies at z ~ 7 have
HeII line emission that is ~1- 3 orders of magnitude lower then that of
Ly$\alpha$, they have high Ly$\alpha$ equivalent width of > 300 $\AA$ and
should be found close to bright star forming galaxies. The HeII 1640 $\AA$ line
is in comfortable reach of next generation telescopes, like the JWST or TMT.
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