Quenching and the UVJ Diagram in the SIMBA Cosmological Simulation

Akins, Hollis B.; Narayanan, Desika; Whitaker, Katherine E.; Davé, Romeel; Lower, Sidney; Bezanson, Rachel; Feldmann, Robert; Kriek, Mariska

doi:10.3847/1538-4357/ac5d3a

“…It may still be possible to catch a quiescent galaxy in its dusty phase if the quenching timescale is longer than the gas depletion timescale. A few galaxies with some measure of dust obscuration (verified via Atacama Large Millimeter/submillimeter Array detections) have been reported in the literature (Schreiber et al 2018;Whitaker et al 2021b) and found in simulations (Akins et al 2022). While it is possible that these galaxies may indeed represent an evolutionary phase for quiescent galaxies, it is equally likely that they are dusty star-forming galaxies masquerading as quiescent galaxies due to their low sSFRs (heavily dependent on the choice of SFH, e.g., Marchesini et al 2010).…”

Section: Possible Limitations Of the (Ugi) S Diagrammentioning

confidence: 91%

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 UVJ diagram (or other similar rest-frame color-color selections; e.g., Arnouts et al 2013;Leja et al 2019;Antwi-Danso et al 2022) has become ubiquitous to distinguish between star-forming and quiescent galaxies (Brammer et al 2009;Williams et al 2009;Whitaker et al 2011;Ilbert et al 2013;Muzzin et al 2013;Davidzon et al 2017;Akins et al 2022). While rest-frame color selections have been used when studying integrated galaxy properties, the comparably worse sensitivity and spatial resolution of Spitzer/IRAC (i.e., the only instrument able to image the rest-frame J band at z  1) has limited resolved studies of high-redshift galaxies.…”

Section: Introductionmentioning

confidence: 99%

Early JWST Imaging Reveals Strong Optical and NIR Color Gradients in Galaxies at z ∼ 2 Driven Mostly by Dust

Miller

¹

,

Whitaker

²

,

Nelson

³

et al. 2022

ApJL

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Recent studies have shown that galaxies at cosmic noon are redder in the center and bluer in the outskirts, mirroring results in the local universe. These color gradients could be caused by gradients in either the stellar age or dust opacity; however, distinguishing between these two causes is impossible with rest-frame optical photometry alone. Here we investigate the underlying causes of the gradients from spatially resolved rest-frame U − V versus V − J color–color diagrams measured from early observations with the James Webb Space Telescope. We use 1–4 μm NIRCam photometry from the CEERS survey of a sample of 54 galaxies with log M * / M ⊙ > 10 at redshifts 1.7 < z < 2.3 selected from the 3D-HST catalog. We model the light profiles in the F115W, F200W, and F356W NIRCam bands using imcascade, a Bayesian implementation of the multi-Gaussian expansion technique that flexibly represents galaxy profiles using a series of Gaussians. We construct resolved rest-frame U − V and V − J color profiles. The majority of star-forming galaxies have negative gradients (i.e., redder in the center, bluer in the outskirts) in both U − V and V − J colors consistent with radially decreasing dust attenuation. A smaller population (roughly 15%) of star-forming galaxies have positive U − V but negative V − J gradients implying centrally concentrated star formation. For quiescent galaxies, we find a diversity of UVJ color profiles, with roughly one-third showing star formation in their center. This study showcases the potential of JWST to study the resolved stellar populations of galaxies at cosmic noon.

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“…Although the differences are slight, the implications of the lack of overlap in parameter space are potentially significant. For instance, several uncertainties in the forward modeling of the Cosmic Sands galaxies exist, including the stellar population modeling (the IMF, stellar isochrones, and the stellar spectral library chosen to model the luminosity of the star particles; see, e.g., Akins et al 2022), the handling of unresolved emission from H II and photodissociation regions in the birth-clouds surrounding young stars, and the assumed optical properties of the dust grains and thus the underlying extinction curve of the galaxy spectrum. Modifying the optical properties of the dust grains would propagate changes in the resulting infrared luminosity for the same dust and stellar mass values.…”

Section: Dust Properties and Infrared Luminositiesmentioning

confidence: 99%

Cosmic Sands: The Origin of Dusty, Star-forming Galaxies in the Epoch of Reionization

Lower

¹

,

Narayanan

²

,

Li

³

et al. 2023

ApJ

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We present the Cosmic Sands suite of cosmological zoom-in simulations based on the simba galaxy formation model in order to study the buildup of the first massive and dusty galaxies in the early universe. Residing in the most massive halos, we find that the compact proto-massive galaxies undergo nearly continuous mergers with smaller subhalos, boosting star formation rates (SFRs) and the buildup of stellar mass. The galaxies are already appreciably chemically evolved by z = 7, with modeled dust masses comparable to those inferred from observations in the same epoch, except for the most extreme systems. We track gas accretion onto the galaxies to understand how extreme SFRs can be sustained by these early systems. We find that smooth gas accretion can maintain SFRs above 250 M ⊙ yr−1, but to achieve SFRs that boost galaxies well above the main sequence, a larger perturbation like a gas-rich major merger is necessary to trigger a starburst episode. Post-processing the Cosmic Sands simulations with dust RT, we find that, while the infrared luminosities of the most-dust-rich galaxies are comparable to local ULIRGs, they are substantially dimmer than classical z = 2 submillimeter galaxies. We end with a discussion on the possible reasons for this discrepancy at the highest masses and the future work we intend to carry out to study the chemical enrichment of the earliest dusty galaxies.

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Quenching and the UVJ Diagram in the SIMBA Cosmological Simulation

Cited by 18 publications

References 137 publications

Beyond UVJ: Color Selection of Galaxies in the JWST Era

Beyond UVJ: Color Selection of Galaxies in the JWST Era

Early JWST Imaging Reveals Strong Optical and NIR Color Gradients in Galaxies at z ∼ 2 Driven Mostly by Dust

Cosmic Sands: The Origin of Dusty, Star-forming Galaxies in the Epoch of Reionization

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