Observing EAGLE galaxies with JWST: predictions for Milky Way progenitors and their building blocks. Issue 3 (29th August 2022)

• Record Type: Journal Article
• Authors: Evans, Tilly A; Fattahi, Azadeh; Deason, Alis J; Frenk, Carlos S
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 516:Issue 3(2022)
• Page Start: 3861
• Page End: 3877
• Publication Date: 2022-08-29
• Subjects: methods: numerical -- galaxy: evolution -- galaxy: formation; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac2410
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present predictions, derived from the EAGLE ΛCDM cosmological hydrodynamical simulations, for the abundance and properties of galaxies expected to be detected at high redshift by the James Webb Space Telescope ( JWST ). We consider the galaxy population as a whole and focus on the sub-population of progenitors of Milky Way (MW) analogues, defined to be galaxies with accretion histories similar to the MW's, that is, galaxies that underwent a merger resembling the Gaia-Enceladus-Sausage (GES) event and that contain an analogue of the Large Magellanic Cloud (LMC) satellite today. We derive the luminosity function of all EAGLE galaxies in JWST /NIRCam passbands, in the redshift range z = 2 − 8, taking into account dust obscuration and different exposure times. For an exposure time of T = 10 5 s, average MW progenitors are observable as far back as z ∼ 6 in most bands, and this changes to z ∼ 5 and z ∼ 4 for the GES and LMC progenitors, respectively. The progenitors of GES and LMC analogues are, on average, ∼2 and ∼1 mag fainter than the MW progenitors at most redshifts. They lie, on average, within ∼60 and 30 arcsec, respectively, of their future MW host at all times, and thus will appear within the field of view of JWST /NIRCam. We conclude that galaxies resembling the main progenitor of the MW and its major accreted components should be observable with JWST beyond redshift 2, providing a new and unique window in studying the formation history of our own galaxy.