Upper limits on the mass and luminosity of Population III-dominated galaxies

Abstract

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 $M_{\mathrm{halo}}\sim 1.5\times 10^8-1.1\times 10^9{\mathrm{M}}_{\odot }$, that they have Ly$\alpha$ luminosities of $L_{\mathrm{Ly}\alpha }\sim 3.0\times 10^{42}-2.1\times 10^{43}$ erg/s, stellar mass of $M_{\mathrm{star}}\sim 0.8\times 10^5-2.5\times 10^6{\mathrm{M}}_{\odot }$, and outflowing gas with velocities $V_{\mathrm{out}}\sim 40$ 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 $\mathring{A}$ and should be found close to bright star forming galaxies. The HeII 1640 $\mathring{A}$ line is in comfortable reach of next generation telescopes, like the JWST or TMT.

5 pages, 1 figure, accepted for publication in MNRAS Letters

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Cited by in corpus (3)

• Accelerating early massive galaxy formation with primordial black holes
• When did Population III star formation end?
• The Effects of Radiative Feedback and Supernova Induced Turbulence on Early Galaxies