# Are the newly-discovered z ∼13 drop-out sources starburst galaxies or quasars?

Fabio Pacucci*, Pratika Dayal, Yuichi Harikane, Akio K. Inoue, Abraham Loeb

*この研究の対応する著者

2 被引用数 (Scopus)

## 抄録

The detection of two z ∼13 galaxy candidates has opened a new window on galaxy formation at an era only 330 Myr after the big bang. Here, we investigate the physical nature of these sources: are we witnessing star forming galaxies or quasars at such early epochs? If powered by star formation, the observed ultraviolet (UV) luminosities and number densities can be jointly explained if: (i) these galaxies are extreme star-formers with star formation rates 5-24 × higher than those expected from extrapolations of average lower-redshift relations; (ii) the star formation efficiency increases with halo mass and is countered by increasing dust attenuation from z ∼10-5; (iii) they form stars with an extremely top-heavy initial mass function. The quasar hypothesis is also plausible, with the UV luminosity produced by black holes of $\sim 10^8 \, \rm M_\odot$ accreting at or slightly above the Eddington rate (fEdd ∼1.0). This black hole mass at z ∼13 would require very challenging, but not implausible, growth parameters. If spectroscopically confirmed, these two sources will represent a remarkable laboratory to study the Universe at previously inaccessible redshifts.

本文言語 English L6-L10 Monthly Notices of the Royal Astronomical Society: Letters 514 1 https://doi.org/10.1093/mnrasl/slac035 Published - 2022 7月 1

• 天文学と天体物理学
• 宇宙惑星科学

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