The recent James Webb Space Telescope tentative discovery of a population of super-early (redshift z > 10), relatively massive (stellar mass M* = 108-109M⊙) and evolved (metallicity Z ≈ 0.1 Z⊙) galaxies, which nevertheless show blue (β ≃ -2.6) spectra, and very small dust attenuation (AV ≲ 0.02), challenges our interpretation of these systems. To solve the puzzle, we propose two solutions in which dust is either (a) ejected by radiation pressure, or (b) segregated with respect to UV-emitting regions. We clarify the conditions for which the two scenarios apply, and show that they can be discriminated by ALMA observations, such as the recent non-detection of the 88μm dust continuum in GHZ2 (z ≃ 12) favouring dust ejection.

Blue monsters : why are JWST super-early, massive galaxies so blue?

Ziparo, Francesco
;
Ferrara, Andrea;Sommovigo, Laura;Kohandel, Mahsa
2023

Abstract

The recent James Webb Space Telescope tentative discovery of a population of super-early (redshift z > 10), relatively massive (stellar mass M* = 108-109M⊙) and evolved (metallicity Z ≈ 0.1 Z⊙) galaxies, which nevertheless show blue (β ≃ -2.6) spectra, and very small dust attenuation (AV ≲ 0.02), challenges our interpretation of these systems. To solve the puzzle, we propose two solutions in which dust is either (a) ejected by radiation pressure, or (b) segregated with respect to UV-emitting regions. We clarify the conditions for which the two scenarios apply, and show that they can be discriminated by ALMA observations, such as the recent non-detection of the 88μm dust continuum in GHZ2 (z ≃ 12) favouring dust ejection.
2023
Settore FIS/05 - Astronomia e Astrofisica
dust, extinction; galaxies: evolution; galaxies: formation; galaxies: high-redshift
   The Interstellar Medium of High Redshift Galaxies (INTERSTELLAR)
   INTERSTELLAR
   European Commission
   H2020
   740120
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/143303
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