Massive high-redshift quiescent galaxies with JWST

Nanayakkara, Themiya; Esdaile, James; Glazebrook, Karl; Salcedo, Juan M. Espejo; Durré, Mark; Jacobs, Colin

doi:10.1017/pasa.2021.61

“…However, given that passive fractions are <10% at z > 4 (e.g., Santini et al 2021), by z ∼ 6, we will be witnessing the emergence of the first quiescent galaxies. These quiescent galaxies will be some of the first to have started forming stars and quench and will be important for answering questions about structure formation in the early universe and settling debates about quenching mechanisms (see Nanayakkara et al 2022 for a review). With this in mind, it is ever so important that we select pure and complete samples of quiescent galaxies for spectroscopic follow-up so that we do not miss any of this interesting population.…”

Section: The Beginning Of the Endmentioning

confidence: 99%

Beyond UVJ: Color Selection of Galaxies in the JWST Era

Antwi-Danso

¹

,

Papovich

²

,

Leja

³

et al. 2023

ApJ

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We present a new rest-frame color–color selection method using synthetic u s − g s and g s − i s , (ugi) s colors to identify star-forming and quiescent galaxies. Our method is similar to the widely used U − V versus V − J (UVJ) diagram. However, UVJ suffers known systematics. Spectroscopic campaigns have shown that UVJ-selected quiescent samples at z ≳ 3 include ∼10%–30% contamination from galaxies with dust-obscured star formation and strong emission lines. Moreover, at z > 3, UVJ colors are extrapolated because the rest-frame band shifts beyond the coverage of the deepest bandpasses at <5 μm (typically Spitzer/IRAC 4.5 μm or future JWST/NIRCam observations). We demonstrate that (ugi) s offers improvements to UVJ at z > 3, and can be applied to galaxies in the JWST era. We apply (ugi) s selection to galaxies at 0.5 < z < 6 from the (observed) 3D-HST and UltraVISTA catalogs, and to the (simulated) JAGUAR catalogs. We show that extrapolation can affect (V − J)0 color by up to 1 mag, but changes ( g s − i s ) 0 color by ≤0.2 mag, even at z ≃ 6. While (ugi) s -selected quiescent samples are comparable to UVJ in completeness (both achieve ∼85%–90% at z = 3–3.5), (ugi) s reduces contamination in quiescent samples by nearly a factor of 2, from ≃35% to ≃17% at z = 3, and from ≃60% to ≃33% at z = 6. This leads to improvements in the true-to-false-positive ratio (TP/FP), where we find TP/FP ≳2.2 for (ugi) s at z ≃ 3.5 − 6, compared to TP/FP < 1 for UVJ-selected samples. This indicates that contaminants will outnumber true quiescent galaxies in UVJ at these redshifts, while (ugi) s will provide higher-fidelity samples.

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“…The challenge lies in unraveling the intricate connections between the star formation environment and the IMF (Hopkins 2018;Smith 2020). Variations of the IMF profoundly impact our interpretations of stellar systems, influencing estimates of their masses (Bernardi et al 2023;Haslbauer et al 2024), ages (Martín-Navarro 2016; Saracco et al 2020), star formation rates (SFRs; Jerábková et al 2018;Kroupa & Jerabkova 2021), dynamical evolution (Wang et al 2021;Nanayakkara et al 2022), and chemical evolution (Yan et al 2019b;Yan 2021;Mucciarelli et al 2021;Wirth et al 2022;Tang et al 2023).…”

Section: Introductionmentioning

confidence: 99%

The Variation in the Galaxy-wide Initial Mass Function for Low-mass Stars: Modeling and Observational Insights

Yan,

Li,

Kroupa

et al. 2024

ApJ

1

0

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The stellar initial mass function (IMF) characterizes the mass distribution of newly formed stars in various cosmic environments, serving as a fundamental assumption in astrophysical research. Recent findings challenge the prevalent notion of a universal and static IMF, proposing instead that the IMF’s shape is contingent upon the star formation environment. In this study, we analyze the galaxy-wide variation in the IMF for low-mass stars in both dwarf and massive galaxies with diverse observational methods. Despite systematic discrepancies between different approaches, an IMF model with a metallicity-dependent slope for the low-mass stars aligns with the majority of observations, indicating a high degree of uniformity in the star formation processes across the Universe. We also emphasize the need for a more comprehensive understanding of the variation in the low-mass IMF, considering measurement biases and factors beyond metallicity.

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“…While the quiescent galaxy population is established at z < 2, there are open questions regarding their progenitors and when and how the first quiescent galaxies emerge. With the advent of sensitive infrared detectors and surely the launch of the James Webb Space Telescope (JWST), it became feasible to spectroscopically confirm quiescent galaxies at the epoch of reionization at z = 6 (Glazebrook et al 2017;Schreiber et al 2018;Tanaka et al 2019;Forrest et al 2020;Valentino et al 2020;D'Eugenio et al 2021;Kubo et al 2021;Nanayakkara et al 2022;Carnall et al 2023aCarnall et al , 2023bValentino et al 2023;Looser et al 2024). Most of these findings are massive galaxies (10 10 M e ) that are thought to be quiescent for many hundreds of Myr to 1 Gyr.…”

Section: Introductionmentioning

confidence: 99%

Dead or Alive? How Bursty Star Formation and Patchy Dust Can Cause Temporary Quiescence in High-redshift Galaxies

Faisst,

Morishita

2024

ApJ

0

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The recent discovery of a galaxy at z = 7.3 with undetected optical emission lines and a blue UV-to-optical continuum ratio in JWST spectroscopy is surprising and needs to be explained physically. Here, we explore two possibilities that could cause such a seemingly quiescent ∼5 × 108 M ⊙ galaxy in the early Universe: (i) stochastic variations in the star formation history (SFH) and (ii) the effect of spatially varying dust attenuation on the measured line and continuum emission properties. Both scenarios can play out at the same time to amplify the effect. A stochastic star formation model (similar to realistic SFHs from hydrodynamical simulations of similar-mass galaxies) can create such observed properties if star formation is fast-varying with a correlation time of <150 Myr given a reasonable burst amplitude of ∼0.6 dex. The total time spent in this state is less than 20 Myr, and the likelihood of such a state to occur over 500 Myr at z = 7 is ∼50% (consistent with current observations). On the other hand, we show that a spectrum with blue UV continuum and lack of emission lines can be reproduced by a blue+red composite spectrum. The UV continuum is emitted from dust-free density-bounded H ii regions (blue component), while the red component is a dust-obscured starburst with weakened emission lines due to strong differential dust attenuation between stellar and nebular emission. Future resolving far-infrared observations with the Atacama Large Millimeter/submillimeter Array will shed light on the latter scenario.

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Massive high-redshift quiescent galaxies with JWST

Cited by 9 publications

References 101 publications

Beyond UVJ: Color Selection of Galaxies in the JWST Era

Beyond UVJ: Color Selection of Galaxies in the JWST Era

The Variation in the Galaxy-wide Initial Mass Function for Low-mass Stars: Modeling and Observational Insights

Dead or Alive? How Bursty Star Formation and Patchy Dust Can Cause Temporary Quiescence in High-redshift Galaxies

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