TY - JOUR
T1 - Recent star formation in a massive slowly quenched lensed quiescent galaxy at z=1.88
AU - Akhshik, Mohammad
AU - Whitaker, Katherine E.
AU - Leja, Joel
AU - Mahler, Guillaume
AU - Sharon, Keren
AU - Brammer, Gabriel
AU - Toft, Sune
AU - Bezanson, Rachel
AU - Man, Allison
AU - Nelson, Erica J.
AU - Pacifici, Camilla
AU - Wellons, Sarah
AU - Williams, Christina C.
N1 - Funding Information:
We would like to thank the anonymous referee for sharing valuable comments and questions that helped us improve the draft significantly. M.A. gratefully acknowledges support by NASA under award No. 80NSSC19K1418. This work is based on observations made with the NASA/ESA Hubble Space Telescope, HST-GO-14622, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. K.W. wishes to acknowledge funding from the Alfred P. Sloan Foundation. S.T. and G.B. acknowledge support from the ERC Consolidator Grant funding scheme (project ConTExt, grant No. 648179). The Cosmic Dawn Center is funded by the Danish National Research Foundation under grant No. 140. C.C.W acknowledges support from the National Science Foundation Astronomy and Astrophysics Fellowship grant AST-1701546. The Dunlap Institute is funded through an endowment established by the David Dunlap family and the University of Toronto.
Publisher Copyright:
© 2021. The American Astronomical Society.
PY - 2021/1/20
Y1 - 2021/1/20
N2 - In this Letter, we reconstruct the formation pathway of MRG-S0851, a massive, logM*M⊙ = 11.02 ±0.04, strongly lensed, red galaxy at z = 1.883 ± 0.001. While the global photometry and spatially resolved outskirts of MRG-S0851 imply an early formation scenario with a slowly decreasing or constant star formation history, a joint fit of 2D grism spectroscopy and photometry reveals a more complex scenario: MRG-S0851 is likely to be experiencing a centrally concentrated rejuvenation in the inner ∼1 kpc in the last ∼100 Myr of evolution. We estimate 0.5 ± 0.1% of the total stellar mass is formed in this phase. Rejuvenation episodes are suggested to be infrequent for massive galaxies at z ∼ 2, but as our analyses indicate, more examples of complex star formation histories may yet be hidden within existing data. By adding an FUV color criterion to the standard U-V/V-J diagnostic-thereby heightening our sensitivity to recent star formation-we show that we can select populations of galaxies with similar spectral energy distributions to that of MRG-S0851, but note that deep follow-up spectroscopic observations and/or spatially resolved analyses are necessary to robustly confirm the rejuvenation of these candidates. Using our criteria with MRG-S0851 as a prototype, we estimate that ∼1% of massive quiescent galaxies at 1 < z < 2 are potentially rejuvenating.
AB - In this Letter, we reconstruct the formation pathway of MRG-S0851, a massive, logM*M⊙ = 11.02 ±0.04, strongly lensed, red galaxy at z = 1.883 ± 0.001. While the global photometry and spatially resolved outskirts of MRG-S0851 imply an early formation scenario with a slowly decreasing or constant star formation history, a joint fit of 2D grism spectroscopy and photometry reveals a more complex scenario: MRG-S0851 is likely to be experiencing a centrally concentrated rejuvenation in the inner ∼1 kpc in the last ∼100 Myr of evolution. We estimate 0.5 ± 0.1% of the total stellar mass is formed in this phase. Rejuvenation episodes are suggested to be infrequent for massive galaxies at z ∼ 2, but as our analyses indicate, more examples of complex star formation histories may yet be hidden within existing data. By adding an FUV color criterion to the standard U-V/V-J diagnostic-thereby heightening our sensitivity to recent star formation-we show that we can select populations of galaxies with similar spectral energy distributions to that of MRG-S0851, but note that deep follow-up spectroscopic observations and/or spatially resolved analyses are necessary to robustly confirm the rejuvenation of these candidates. Using our criteria with MRG-S0851 as a prototype, we estimate that ∼1% of massive quiescent galaxies at 1 < z < 2 are potentially rejuvenating.
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U2 - 10.3847/2041-8213/abd416
DO - 10.3847/2041-8213/abd416
M3 - Article
AN - SCOPUS:85100304119
SN - 2041-8205
VL - 907
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - abd416
ER -