JWST Insight into a Lensed HST-dark Galaxy and Its Quiescent Companion at z = 2.58

Kokorev, Vasily; Jin, S.; Magdis, G.; Caputi, K.; Valentino, F.; Dayal, Pratika; Trebitsch, Maxime; Brammer, Gabriel; Fujimoto, Seiji; Bauer, F. E.; Iani, Edoardo; Kohno, Kotaro; Sesé, David Blánquez; Gómez-Guijarro, Carlos; Rinaldi, Pierluigi; Navarro-Carrera, Rafael

doi:10.3847/2041-8213/acbd9d

“…Finally, it is also possible to envision that the AGN can be embedded within an extremely dusty galaxy that surrounds the object and yet remains completely JWST-dark due to dust obscuration and low surface brightness. The implications of such dusty galaxies existing at high z were briefly explored in Kokorev et al (2023), who presented an overview of a highly obscured (A V ∼ 4) galaxy at z = 2.58. By adapting the full UVto-submillimeter SED from Kokorev et al and scaling it to our ALMA photometry, we compute a stellar mass limit of  * < M M log 9.5 10 (…”

Section: Template Fittingmentioning

confidence: 99%

UNCOVER: A NIRSpec Identification of a Broad-line AGN at z = 8.50

Kokorev,

Fujimoto,

Labbe

et al. 2023

ApJL

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Deep observations with the James Webb Space Telescope (JWST) have revealed an emerging population of red pointlike sources that could provide a link between the postulated supermassive black hole seeds and observed quasars. In this work, we present a JWST/NIRSpec spectrum from the JWST Cycle 1 UNCOVER Treasury survey of a massive accreting black hole at z = 8.50 displaying a clear broad-line component as inferred from the Hβ line with FWHM = 3439 ± 413 km s−1, typical of the broad-line region of an active galactic nucleus (AGN). The AGN nature of this object is further supported by high ionization, as inferred from emission lines, and a point-source morphology. We compute a black hole mass of log 10 ( M BH / M ⊙ ) = 8.17 ± 0.42 and a bolometric luminosity of L bol ∼ 6.6 × 1045 erg s−1. These values imply that our object is accreting at ∼40% of the Eddington limit. Detailed modeling of the spectral energy distribution in the optical and near-infrared, together with constraints from ALMA, indicate an upper limit on the stellar mass of log 10 ( M * / M ⊙ ) < 8.7 , which would lead to an unprecedented ratio of black hole to host mass of at least ∼30%. This is orders of magnitude higher compared to the local QSOs but consistent with recent AGN studies at high redshift with JWST. This finding suggests that a nonnegligible fraction of supermassive black holes either started out from massive seeds and/or grew at a super-Eddington rate at high redshift. Given the predicted number densities of high-z faint AGN, future NIRSpec observations of larger samples will allow us to further investigate galaxy–black hole coevolution in the early Universe.

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“…Another, perhaps more speculative, explanation for this widespread (and relatively uniform) dust reddening in this (modestly inclined, in contrast to Nelson et al 2023; see also Kokorev et al 2023) galaxy is a dusty wind, as is seen on similar scales in M 82 (e.g., Yamagishi et al 2012;Beirão et al 2015), Mg II absorbers at higher redshifts (Ménard & Fukugita 2012), and also as theoretically expected (e.g., Krumholz & Thompson 2013). To illustrate the plausibility of this explanation, we assume a Milky Way gas-to-dust ratio, for which an A V ∼ 3 corresponds to a hydrogen column density of ∼10 22 cm −2 (Bouchet et al 1985).…”

Section: Morphologies and Structuresmentioning

confidence: 90%

“…The simplest explanation for the widespread high A V in 850.1 may be that this galaxy has a very dusty disk (even if the gas fraction for the system is low; see Section 3.5), as well as an even more obscured nuclear region. Kokorev et al (2023) presented a similar spatially resolved JWST analysis of a z = 2.58 Atacama Large Millimeter/submillimeter Array (ALMA)-detected galaxy that shows a comparably high dust extinction over a very wide area, although their system appears to be much more highly inclined than 850.1. Such extended dust disks have also been reported in similarly dust-rich galaxies (e.g., Hodge et al 2016;Gullberg et al 2019), in conjunction with more compact dust continuum structures that have been interpreted as bars and rings (Hodge et al 2019).…”

Section: Morphologies and Structuresmentioning

confidence: 99%

“…The high resolution and depth of the JWST and HST imaging of these sources can be used to go beyond the analysis just described to undertake resolved SED modeling of the sources to investigate their internal structures. Specifically, to map the distribution of stellar mass and dust reddening within the two systems (see also, Duncan et al 2023;Kokorev et al 2023). To perform this analysis, 9″ × 9″ thumbnails were extracted from the JWST and HST imaging centered on 850.1 and 850.2.…”

Section: Resolved Sed Modelingmentioning

confidence: 99%

“…The potential for entire classes of dusty, massive galaxies (detectable in the (sub)millimeter or the mid-infrared with Spitzer/IRAC and variously termed optically/near-infrared faint/dark or less precisely "HST-dark") to be missed from UV, visible-and near-infrared-selected samples, has been a concern for studies attempting to construct stellar-mass-limited galaxy surveys at z > 1 (e.g., Dey et al 1999;Caputi et al 2012;Simpson et al 2014;Wang et al 2019). With the launch of JWST, there has been a renewed appreciation of the significant role of dust in defining the observed visible to nearinfrared properties of high-redshift galaxy populations (e.g., Barrufet et al 2023;Bisigello et al 2023;Kokorev et al 2023;Magnelli et al 2023;Pérez-González et al 2023).…”

Section: Introductionmentioning

confidence: 99%

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Hidden Giants in JWST's PEARLS: An Ultramassive z = 4.26 Submillimeter Galaxy that Is Invisible to HST

Smail,

Dudzevičiūtė,

Gurwell

et al. 2023

ApJ

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We present a multiwavelength analysis using the Submillimeter Array (SMA), James Clerk Maxwell Telescope, NOEMA, JWST, the Hubble Space Telescope (HST), and the Spitzer Space Telescope of two dusty strongly star-forming galaxies, 850.1 and 850.2, seen through the massive cluster lens A 1489. These SMA-located sources both lie at z = 4.26 and have bright dust continuum emission, but 850.2 is a UV-detected Lyman-break galaxy, while 850.1 is undetected at ≲ 2 μm, even with deep JWST/NIRCam observations. We investigate their stellar, interstellar medium, and dynamical properties, including a pixel-level spectral energy distribution analysis to derive subkiloparsec-resolution stellar-mass and A V maps. We find that 850.1 is one of the most massive and highly obscured, A V ∼ 5, galaxies known at z > 4 with M * ∼1011.8 M ⊙ (likely forming at z > 6), and 850.2 is one of the least massive and least obscured, A V ∼ 1, members of the z > 4 dusty star-forming population. The diversity of these two dust-mass-selected galaxies illustrates the incompleteness of galaxy surveys at z ≳ 3–4 based on imaging at ≲ 2 μm, the longest wavelengths feasible from HST or the ground. The resolved mass map of 850.1 shows a compact stellar-mass distribution, R e mass ∼1 kpc, but its expected evolution means that it matches both the properties of massive, quiescent galaxies at z ∼ 1.5 and ultramassive early-type galaxies at z ∼ 0. We suggest that 850.1 is the central galaxy of a group in which 850.2 is a satellite that will likely merge in the near future. The stellar morphology of 850.1 shows arms and a linear bar feature that we link to the active dynamical environment it resides within.

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JWST CEERS probes the role of stellar mass and morphology in obscuring galaxies

Gómez-Guijarro¹,

Magnelli²,

Elbaz³

et al. 2023

A&A

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In recent years, observations have uncovered a population of massive galaxies that are invisible or very faint in deep optical/near-infrared (near-IR) surveys but brighter at longer wavelengths. However, the nature of these optically dark or faint galaxies (OFGs; one of several names given to these objects) is highly uncertain. In this work, we investigate the drivers of dust attenuation in the JWST era. In particular, we study the role of stellar mass, size, and orientation in obscuring star-forming galaxies (SFGs) at 3 < z < 7.5, focusing on the question of why OFGs and similar galaxies are so faint at optical/near-IR wavelengths. We find that stellar mass is the primary proxy for dust attenuation, among the properties studied. Effective radius and axis ratio do not show a clear link with dust attenuation, with the effect of orientation being close to random. However, there is a subset of highly dust attenuated (AV > 1, typically) SFGs, of which OFGs are a specific case. For this subset, we find that the key distinctive feature is their compact size (for massive systems with log(M*/M⊙) > 10); OFGs exhibit a 30% smaller effective radius than the average SFG at the same stellar mass and redshift. On the contrary, OFGs do not exhibit a preference for low axis ratios (i.e., edge-on disks). The results in this work show that stellar mass is the primary proxy for dust attenuation and compact stellar light profiles behind the thick dust columns obscuring typical massive SFGs.

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JWST Insight into a Lensed HST-dark Galaxy and Its Quiescent Companion at z = 2.58

Cited by 18 publications

References 98 publications

UNCOVER: A NIRSpec Identification of a Broad-line AGN at z = 8.50

UNCOVER: A NIRSpec Identification of a Broad-line AGN at z = 8.50

Hidden Giants in JWST's PEARLS: An Ultramassive z = 4.26 Submillimeter Galaxy that Is Invisible to HST

JWST CEERS probes the role of stellar mass and morphology in obscuring galaxies

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