@article{20494, abstract = {The James Webb Space Telescope is revolutionising our ability to understand the host galaxies and local environments of high-z quasars. Here we obtain a comprehensive understanding of the host galaxy of the z = 7.08 quasar J1120+0641 by combining NIRSpec integral field spectroscopy with NIRCam photometry of the host continuum emission. Our emission-line maps reveal that this quasar host is undergoing a merger with a bright companion galaxy. The quasar host and the companion have similar dynamical masses of ∼1010 M⊙, suggesting that this is a major galaxy interaction. Through detailed quasar subtraction and SED fitting using the NIRCam data, we obtained an estimate of the host stellar mass of M* = (3.0−1.4+2.5) × 109 M⊙, with M∗ = (2.7−0.5+0.5) × 109 M⊙ for the companion galaxy. Using the Hβ Balmer line, we estimated a virial black hole mass of MBH = (1.9−1.1+2.9) × 109 M⊙. Thus, J1120+0641 has an extreme black hole–stellar mass ratio of MBH/M* = 0.63−0.31+0.54, which is ∼3 dex larger than expected by the local scaling relations between black hole and stellar mass. J1120+0641 is powered by an overmassive black hole with the highest reported black hole–stellar mass ratio in a quasar host that is currently undergoing a major merger. These new insights highlight the power of JWST for measuring and understanding these extreme first quasars.}, author = {Marshall, Madeline A. and Yue, Minghao and Eilers, Anna Christina and Scholtz, Jan and Perna, Michele and Willott, Chris J. and Maiolino, Roberto and Übler, Hannah and Arribas, Santiago and Bunker, Andrew J. and Charlot, Stephane and Rodríguez Del Pino, Bruno and Böker, Torsten and Carniani, Stefano and Circosta, Chiara and Cresci, Giovanni and D'Eugenio, Francesco and Jones, Gareth C. and Venturi, Giacomo and Bordoloi, Rongmon and Kashino, Daichi and Mackenzie, Ruari and Matthee, Jorryt J and Naidu, Rohan and Simcoe, Robert A.}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, publisher = {EDP Sciences}, title = {{GA-NIFS and EIGER: A merging quasar host at z = 7 with an overmassive black hole}}, doi = {10.1051/0004-6361/202452650}, volume = {702}, year = {2025}, } @article{20544, abstract = {The physical nature of little red dots (LRDs), a population of compact red galaxies revealed by JWST, remains unclear. Photometric samples were constructed from varying selection criteria with limited spectroscopic follow-up available to test intrinsic spectral shapes and the prevalence of broad emission lines. We used the RUBIES survey, a large spectroscopic program with wide color-morphology coverage and homogeneous data quality, to systematically analyze the emission-line kinematics, spectral shapes, and morphologies of ∼1500 galaxies at z > 3.1. We identified broad Balmer lines via a novel fitting approach that simultaneously models NIRSpec/PRISM and G395M spectra, yielding 80 broad-line sources with 28 (35%) at z > 6. A large subpopulation naturally emerged from the broad Balmer line sources, with 36 exhibiting v-shaped UV-to-optical continua and a dominant point source component in the rest-optical; we define these as spectroscopic LRDs, constituting the largest such sample to date. Strikingly, the spectroscopic LRD population is largely recovered when either a broad line or rest-optical point source is required in combination with a v-shaped continuum, suggesting an inherent link between these three defining characteristics. We compared the spectroscopic LRD sample to published photometric searches. Although these selections have high accuracy, 80%−95% down to F444W < 26.5, only 50%−80% of the RUBIES LRDs were photometrically identified, depending on the selection criteria used. The remainder were missed due to a mixture of faint rest-UV photometry, comparatively blue rest-optical colors, or highly uncertain photometric redshifts. Our findings highlight that well-selected spectroscopic campaigns are essential for robust LRD identification, while photometric criteria require refinement to capture the full population.}, author = {Hviding, Raphael E. and de Graaff, Anna and Miller, Tim B. and Setton, David J. and Greene, Jenny E. and Labbé, Ivo and Brammer, Gabriel and Bezanson, Rachel and Boogaard, Leindert A. and Cleri, Nikko J. and Leja, Joel and Maseda, Michael V. and McConachie, Ian and Matthee, Jorryt J and Naidu, Rohan P. and Oesch, Pascal A. and Wang, Bingjie and Whitaker, Katherine E. and Williams, Christina C.}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, publisher = {EDP Sciences}, title = {{RUBIES: A spectroscopic census of little red dots}}, doi = {10.1051/0004-6361/202555816}, volume = {702}, year = {2025}, } @article{20545, abstract = {The H i gas distribution in damped Lyman $\alpha$ absorbers (DLAs) has remained elusive due to the point-source nature of background quasar emission. Observing DLAs against spatially extended background galaxies provides a new method for constraining their size and structure. Using the Keck Cosmic Web Imager, we present the first ‘silhouette’ image of a DLA at $z=3.34$, identified in the spectrum of a background galaxy at $z=3.61$. Although the silhouette remains unresolved due to limited spatial resolution, this represents a successful proof-of-concept for studying DLA morphology using extended background sources. Possible residual emission in the DLA trough suggests an optical depth contrast exceeding $10^7$ in the internal structure, implying a sharp edge or patchy structure. A Lyman $\alpha$ emitter (LAE) at $z_{\rm LAE}=3.3433\pm 0.0005$, consistent with the DLA redshift, is detected at an angular separation of $1{{_{.}^{\prime\prime}} }73\pm 0{{_{.}^{\prime\prime}} }28$ ($12.9\pm 2.1$ kpc). The DLA is surrounded by three galaxies within 140 kpc in projected distance and 500 km s$^{-1}$ in line-of-sight velocity, indicating that it resides in the circumgalactic medium of the LAE or within a galaxy group/protocluster environment. An O i  $\lambda 1302$ absorption at $z_{\rm OI}=3.3288\pm 0.0004$ is also detected along the line of sight. This absorber may trace metal-enriched outflow from the LAE or a gas-rich galaxy exhibiting the highest star formation activity among the surrounding galaxies. Future large spectroscopic surveys of galaxies will expand such a DLA sample, and three-dimensional spectroscopy for it will shed new light on the role of intergalactic dense gas in galaxy formation and evolution.}, author = {Komori, Fuga and Inoue, Akio K and Mawatari, Ken and Sugahara, Yuma and Umehata, Hideki and Shimakawa, Rhythm and Yamanaka, Satoshi and Hashimoto, Takuya and Matthee, Jorryt J and Misawa, Toru}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {3}, pages = {2943--2957}, publisher = {Oxford University Press}, title = {{The first direct imaging of the silhouette of a damped Lyman α system along the line-of-sight to a background galaxy}}, doi = {10.1093/mnras/staf1622}, volume = {543}, year = {2025}, } @article{20589, abstract = {Context. This paper investigates the star formation histories (SFHs) of a sample of massive galaxies (M⋆ ≥ 1010 M⊙) in the redshift range 1 < z < 4.5. Methods. We analyzed spectro-photometric data, combining broadband photometry from HST and JWST with low-resolution grism spectroscopy from JWST/NIRISS, obtained as part of the MIRI Deep Imaging Survey program. SFHs were derived through spectral energy distribution fitting using two independent codes, BAGPIPES and synthesizer, under various SFH assumptions. This approach enables a comprehensive assessment of the biases introduced by different modeling choices. Results. The inclusion of NIRISS spectroscopy, even with its low resolution, significantly improves constraints on key physical parameters, such as the mass-weighted stellar age (tM) and formation redshift (zform), by narrowing their posterior distributions. The massive galaxies in our sample exhibit rapid stellar mass assembly, forming 50% of their mass between 3 ≤ z ≤ 9. The highest inferred formation redshifts are compatible with elevated star formation efficiencies (ϵ) at early epochs. Nonparametric SFHs generally imply an earlier and slower mass assembly compared to parametric forms, highlighting the sensitivity of inferred formation timescales to the chosen SFH model–particularly for galaxies at z < 2. We find that quiescent galaxies are, on average, older (tM ∼ 1.1 Gyr) and assembled more rapidly at earlier times than their star-forming counterparts. These findings support the “downsizing” scenario, in which more massive and passive systems form earlier and more efficiently.}, author = {Annunziatella, M. and P’Erez-Gonz’Alez, P. G. and Álvarez-Márquez, J. and Costantin, L. and Iani, Edoardo and Labiano, Unknown and Rinaldi, P. and Boogaard, L. and Meyer, R. A. and Östlin, G. and Colina, L. and Melinder, J. and Jermann, I. and Gillman, S. and Langeroodi, D. and Hjorth, J. and Alonso-Herrero, A. and Eckart, A. and Walter, F. and Van Der Werf, P. P. and Bik, A. and Peißker, F. and Caputi, K. I. and García-Marín, M. and Wright, G. and Greve, T. R.}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, publisher = {EDP Sciences}, title = {{MIDIS: Unveiling the star formation history in massive galaxies at 1 < z < 4.5 with spectro-photometric analysis}}, doi = {10.1051/0004-6361/202453298}, volume = {702}, year = {2025}, } @article{20649, abstract = {Ionized proximity zones around luminous quasars provide a unique laboratory to characterize the Lyα emission lines from z > 6 galaxies without significant attenuation from the intergalactic medium (IGM). However, Lyα line measurements for galaxies within high-redshift quasars’ proximity zones have been rare so far. Here we present deep spectroscopic observations obtained with the NIRSpec/Micro-Shutter Assembly (MSA) instrument on the James Webb Space Telescope of galaxies in two z > 6 quasar fields. We measure the Lyα line fluxes for 50 galaxies at 6 < z < 7 with UV absolute magnitude M UV < −19 (median M UV = −19.97), among which 15 are located near the luminous quasars, i.e., within Δv < 2500 km s−1. We find that galaxies near the quasars show significant flux blueward of the systemic Lyα wavelength, and have higher Lyα equivalent width compared to galaxies at similar redshifts that are not located within the quasars’ environment. Our result indicates little or no redshift evolution for the Lyα emitter fraction from z ∼ 6.4 to z ∼ 5. Leveraging the low IGM opacity in the quasars’ vicinity, we evaluate the Lyα escape fraction (f esc Ly α) of high-redshift galaxies. Our analysis suggests that galaxies at 〈z〉 ≈ 6.4 have an average f esc Ly α = 0.14 ± 0.04. This value is consistent with reionization models where the Lyman continuum escape fraction is low ( fescLyC ≲ 0.1 ) for luminous galaxies, and where the most luminous galaxies have only a minor contribution to the total ionizing photon budget. © 2025. The Author(s). Published by the American Astronomical Society.}, author = {Yue, Minghao and Eilers, Anna Christina and Matthee, Jorryt J and Naidu, Rohan P. and Bordoloi, Rongmon and Davies, Frederick B. and Hennawi, Joseph F. and Kashino, Daichi and Mackenzie, Ruari and Simcoe, Robert A.}, issn = {2041-8213}, journal = {The Astrophysical Journal Letters}, number = {1}, publisher = {IOP Publishing}, title = {{Escape fractions from unattenuated Lyα emitters around luminous z > 6 quasars}}, doi = {10.3847/2041-8213/ae0e0e}, volume = {993}, year = {2025}, } @article{20660, abstract = {We used observations from the JWST Emission Line Survey (JELS) to measure the half-light radii (re) of 23 Hα-emitting starforming (SF) galaxies at z = 6.1 in the PRIMER/COSMOS field. Galaxy sizes were measured in JWST near-infrared camera observations in rest-frame Hα (tracing recent star formation) with the F466N and F470N narrow-band filters from JELS, and compared against rest-R- and V -band (tracing established stellar populations) and near-ultraviolet sizes. We find a size–stellar mass(re − M∗) relationship with a slope that is consistent with literature values at lower redshifts, though offset to lowersizes. We observe a large scatter in re at low stellar mass (M∗ < 10^8.4 Mo) which we believe is the result of bursty star formation histories (SFHs) of SF galaxies at the Epoch of Reionization (EoR). We find that the stellar and ionized gas components are similar in size at z = 6.1. The evidence of already-established stellar components in these Hα emitters (HAEs) indicates previous episodes of star formation have occurred. As such, following other JELS studies finding our HAEs are undergoing a current burst of star formation, we believe our results indicate that SF galaxies at the end of the EoR have already experienced a bursty SFH. From our re − M∗ relationship, we find re,F444W = 0.76 ± 0.46 kpc for fixed stellar mass M∗ = 10^9.25 M, which is in agreement with other observations and simulations of SF galaxies in the literature. We find a close-pair (major) merger fraction of (fmaj. merger =0.44 ± 0.22) fmerger = 0.43 ± 0.11 for galaxy separations d <~ 25 kpc, which is in agreement with other z ≈ 6 studies.}, author = {Stephenson, H. M.O. and Stott, J. P. and Pirie, C. A. and Duncan, K. J. and Mcleod, D. J. and Best, P. N. and Brinch, M. and Clausen, M. and Cochrane, R. K. and Dunlop, J. S. and Flury, S. R. and Geach, J. E. and Hale, C. L. and Ibar, E. and Li, Zefeng and Matthee, Jorryt J and Mclure, R. J. and Ossa-Fuentes, L. and Patrick, A. L. and Sobral, D. and Swinbank, A. M.}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {2}, pages = {1412--1431}, publisher = {Oxford University Press}, title = {{The JWST Emission Line Survey (JELS): The sizes and merger fraction of star-forming galaxies during the Epoch of Reionization}}, doi = {10.1093/mnras/staf1725}, volume = {544}, year = {2025}, } @article{20661, abstract = {We analyse James Webb Space Telescope (JWST) Near Infrared Imager and Slitless Spectrograph (NIRISS) and Near Infrared Spectrograph (NIRSpec) spectroscopic observations in the Abell 2744 galaxy cluster field. From approximately 120 candidates, we identify 12 objects with at least two prominent emission lines among [O II] λ3727, H β λ4861, [O III] λ4959, [O III] λ5007, and H α λ6563 that are spectroscopically confirmed by both instruments. Our key findings reveal systematic differences between the two spectrographs based on source morphology and shutter aperture placement. Compact objects show comparable or higher integrated flux in NIRSpec relative to NIRISS (within 1σ uncertainties), while extended sources consistently display higher flux in NIRISS measurements. This pattern reflects NIRSpec’s optimal coverage for compact objects while potentially undersampling extended sources. Quantitative analysis demonstrates that NIRSpec recovers at least 63 per cent of NIRISS-measured flux when the slit covers >15 per cent of the source or when Re < 1 kpc. For lower coverage or larger effective radii, the recovered flux varies from 24 per cent to 63 per cent. When studying the H α λ6563/[O III] λ5007 emission line ratio, we observe that measurements from these different spectrographs can vary by up to ∼0.3 dex, with significant implications for metallicity and star formation rate characterizations for individual galaxies. These results highlight the importance of considering instrumental effects when combining multi-instrument spectroscopic data and demonstrate that source morphology critically influences flux recovery between slit-based and slitless spectroscopic modes in JWST observations.}, author = {Dalmasso, Nicolò and Watson, Peter J. and Treu, Tommaso and Trenti, Michele and Vulcani, Benedetta and Nanayakkara, Themiya and Bradač, Maruša and Jones, Tucker and Boyett, Kristan and Wang, Xin and Mascia, Sara and Pentericci, Laura}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {2}, pages = {1915--1925}, publisher = {Oxford University Press}, title = {{Quantifying spectroscopic flux variations between JWST NIRISS and NIRSpec: Slit losses in emission line measurements of z ∼ 1-3 galaxies}}, doi = {10.1093/mnras/staf1837}, volume = {544}, year = {2025}, } @article{18631, abstract = {Within the established framework of structure formation, galaxies start as systems of low stellar mass and gradually grow into far more massive galaxies. The existence of massive galaxies in the first billion years of the Universe, as suggested by recent observations, seems to challenge this model, as such galaxies would require highly efficient conversion of baryons into stars. An even greater challenge in this epoch is the existence of massive galaxies that have already ceased forming stars. However, robust detections of early massive quiescent galaxies have been challenging due to the coarse wavelength sampling of photometric surveys. Here we report the spectroscopic confirmation with the James Webb Space Telescope of the quiescent galaxy RUBIES-EGS-QG-1 at redshift z = 4.90, 1.2 billion years after the Big Bang. Deep stellar absorption features in the spectrum reveal that the stellar mass of the galaxy of 1011 M⊙ formed in a short 200 Myr burst of star formation, after which star formation activity dropped rapidly and persistently. According to current galaxy formation models, systems with such rapid stellar mass growth and early quenching are too rare to plausibly occur in the small area probed spectroscopically with JWST. Instead, the discovery of RUBIES-EGS-QG-1 implies that early massive quiescent galaxies can be quenched earlier or exhaust gas available for star formation more efficiently than assumed at present.}, author = {De Graaff, Anna and Setton, David J. and Brammer, Gabriel and Cutler, Sam and Suess, Katherine A. and Labbé, Ivo and Leja, Joel and Weibel, Andrea and Maseda, Michael V. and Whitaker, Katherine E. and Bezanson, Rachel and Boogaard, Leindert A. and Cleri, Nikko J. and De Lucia, Gabriella and Franx, Marijn and Greene, Jenny E. and Hirschmann, Michaela and Matthee, Jorryt J and Mcconachie, Ian and Naidu, Rohan P. and Oesch, Pascal A. and Price, Sedona H. and Rix, Hans Walter and Valentino, Francesco and Wang, Bingjie and Williams, Christina C.}, issn = {2397-3366}, journal = {Nature Astronomy}, pages = {280--292}, publisher = {Springer Nature}, title = {{Efficient formation of a massive quiescent galaxy at redshift 4.9}}, doi = {10.1038/s41550-024-02424-3}, volume = {9}, year = {2025}, } @article{21064, abstract = {The James Webb Space Telescope (JWST) is revolutionizing our knowledge of z > 5 galaxies and their actively accreting black holes. Using the JWST Cycle 1 Treasury program Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization (UNCOVER) in the lensing field A2744, we report the identification of a sample of little red dots at 3 < zphot < 7 that likely contain highly reddened accreting supermassive black holes. Using a NIRCam-only selection to F444W < 27.7 mag, we find 26 sources over the ∼45 arcmin^2 field that are blue in F115W − F200W ∼ 0 (or βUV ∼ –2.0 for fλ ∝ λ^β), red in F200W − F444W = 1−4 (βopt ∼ +2.0), and are dominated by a point-source-like central component. Of the 20 sources with deep Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm coverage, none are detected individually or in a stack. For the majority of the sample, spectral energy distribution fits to the JWST+ALMA observations prefer models with hot dust rather than obscured star formation to reproduce the red NIRCam colors and ALMA 1.2 mm nondetections. While compact dusty star formation cannot be ruled out, the combination of extremely small sizes (〈re〉 ≈ 50 pc after correction for magnification), red rest-frame optical slopes, and hot dust can be explained by reddened broad-line active galactic nuclei (AGNs). Our targets have faint M1450 ≈ −14 to −18 mag but inferred bolometric luminosities of Lbol = 10^43–10^46 erg s^−1, reflecting their obscured nature. If the candidates are confirmed as AGNs with upcoming UNCOVER spectroscopy, then we have found an abundant population of reddened luminous AGNs that are at least ten times more numerous than UV-luminous AGNs at the same intrinsic bolometric luminosity.}, author = {Labbe, Ivo and Greene, Jenny E. and Bezanson, Rachel and Fujimoto, Seiji and Furtak, Lukas J. and Goulding, Andy D. and Matthee, Jorryt J and Naidu, Rohan P. and Oesch, Pascal A. and Atek, Hakim and Brammer, Gabriel and Chemerynska, Iryna and Coe, Dan and Cutler, Sam E. and Dayal, Pratika and Feldmann, Robert and Franx, Marijn and Glazebrook, Karl and Leja, Joel and Maseda, Michael and Marchesini, Danilo and Nanayakkara, Themiya and Nelson, Erica J. and Pan, Richard and Papovich, Casey and Price, Sedona H. and Suess, Katherine A. and Wang, Bingjie 冰洁 and Weaver, John R. and Whitaker, Katherine E. and Williams, Christina C. and Zitrin, Adi}, issn = {1538-4357}, journal = {The Astrophysical Journal}, publisher = {IOP Publishing}, title = {{UNCOVER: Candidate red active galactic nuclei at 3 < z < 7 with JWST and ALMA}}, doi = {10.3847/1538-4357/ad3551}, volume = {978}, year = {2024}, } @article{14852, abstract = {The physical conditions giving rise to high escape fractions of ionizing radiation (LyC fesc) in star-forming galaxies – most likely protagonists of cosmic reionization – are not yet fully understood. Using the VLT/MUSE observations of ∼1400 Ly α emitters at 2.9 &lt; z &lt; 6.7, we compare stacked rest-frame UV spectra of candidates for LyC leakers and non-leakers selected based on their Ly α profiles. We find that the stacks of potential LyC leakers, i.e. galaxies with narrow, symmetric Ly α profiles with small peak separation, generally show (i) strong nebular O iii]λ1666, [Si iii]λ1883, and [C iii]λ1907 +C iii]λ1909 emission, indicating a high-ionization state of the interstellar medium (ISM); (ii) high equivalent widths of He iiλ1640 (∼1 − 3 Å), suggesting the presence of hard ionizing radiation fields; (iii) Si ii*λ1533 emission, revealing substantial amounts of neutral hydrogen off the line of sight; (iv) high C ivλλ1548,1550 to [C iii]λ1907 +C iii]λ1909 ratios (C iv/C iii] ≳0.75) , signalling the presence of low column density channels in the ISM. In contrast, the stacks with broad, asymmetric Ly α profiles with large peak separation show weak nebular emission lines, low He iiλ1640 equivalent widths (≲1 Å), and low C iv/C iii] (≲0.25), implying low-ionization states and high-neutral hydrogen column densities. Our results suggest that C iv/C iii] might be sensitive to the physical conditions that govern LyC photon escape, providing a promising tool for identification of ionizing sources among star-forming galaxies in the epoch of reionization.}, author = {Kramarenko, Ivan and Kerutt, J and Verhamme, A and Oesch, P A and Barrufet, L and Matthee, Jorryt J and Kusakabe, H and Goovaerts, I and Thai, T T}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, keywords = {Space and Planetary Science, Astronomy and Astrophysics}, number = {4}, pages = {9853--9871}, publisher = {Oxford University Press}, title = {{Linking UV spectral properties of MUSE Ly α emitters at z ≳ 3 to Lyman continuum escape}}, doi = {10.1093/mnras/stad3853}, volume = {527}, year = {2024}, } @article{15180, abstract = {Characterizing the prevalence and properties of faint active galactic nuclei (AGNs) in the early Universe is key for understanding the formation of supermassive black holes (SMBHs) and determining their role in cosmic reionization. We perform a spectroscopic search for broad Hα emitters at z ≈ 4–6 using deep JWST/NIRCam imaging and wide field slitless spectroscopy from the EIGER and FRESCO surveys. We identify 20 Hα lines at z = 4.2–5.5 that have broad components with line widths from ∼1200–3700 km s−1, contributing ∼30%–90% of the total line flux. We interpret these broad components as being powered by accretion onto SMBHs with implied masses ∼107–8M⊙. In the UV luminosity range MUV,AGN+host = −21 to −18, we measure number densities of ≈10−5 cMpc−3. This is an order of magnitude higher than expected from extrapolating quasar UV luminosity functions (LFs). Yet, such AGN are found in only <1% of star-forming galaxies at z ∼ 5. The number density discrepancy is much lower when compared to the broad Hα LF. The SMBH mass function agrees with large cosmological simulations. In two objects, we detect complex Hα profiles that we tentatively interpret as caused by absorption signatures from dense gas fueling SMBH growth and outflows. We may be witnessing early AGN feedback that will clear dust-free pathways through which more massive blue quasars are seen. We uncover a strong correlation between reddening and the fraction of total galaxy luminosity arising from faint AGN. This implies that early SMBH growth is highly obscured and that faint AGN are only minor contributors to cosmic reionization.}, author = {Matthee, Jorryt J and Naidu, Rohan P. and Brammer, Gabriel and Chisholm, John and Eilers, Anna-Christina and Goulding, Andy and Greene, Jenny and Kashino, Daichi and Labbe, Ivo and Lilly, Simon J. and Mackenzie, Ruari and Oesch, Pascal A. and Weibel, Andrea and Wuyts, Stijn and Xiao, Mengyuan and Bordoloi, Rongmon and Bouwens, Rychard and van Dokkum, Pieter and Illingworth, Garth and Kramarenko, Ivan and Maseda, Michael V. and Mason, Charlotte and Meyer, Romain A. and Nelson, Erica J. and Reddy, Naveen A. and Shivaei, Irene and Simcoe, Robert A. and Yue, Minghao}, issn = {1538-4357}, journal = {The Astrophysical Journal}, keywords = {Space and Planetary Science, Astronomy and Astrophysics}, number = {2}, publisher = {IOP Publishing}, title = {{Little Red Dots: An abundant population of faint active galactic nuclei at z ∼ 5 revealed by the EIGER and FRESCO JWST surveys}}, doi = {10.3847/1538-4357/ad2345}, volume = {963}, year = {2024}, } @article{15170, abstract = {The James Webb Space Telescope is revealing a new population of dust-reddened broad-line active galactic nuclei (AGN) at redshifts z ≳ 5. Here we present deep NIRSpec/Prism spectroscopy from the Cycle 1 Treasury program Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) of 15 AGN candidates selected to be compact, with red continua in the rest-frame optical but with blue slopes in the UV. From NIRCam photometry alone, they could have been dominated by dusty star formation or an AGN. Here we show that the majority of the compact red sources in UNCOVER are dust-reddened AGN: 60% show definitive evidence for broad-line Hα with a FWHM > 2000 km s −1, 20% of the current data are inconclusive, and 20% are brown dwarf stars. We propose an updated photometric criterion to select red z > 5 AGN that excludes brown dwarfs and is expected to yield >80% AGN. Remarkably, among all zphot > 5 galaxies with F277W – F444W > 1 in UNCOVER at least 33% are AGN regardless of compactness, climbing to at least 80% AGN for sources with F277W – F444W > 1.6. The confirmed AGN have black hole masses of 107–109M⊙. While their UV luminosities (−16 > MUV > −20 AB mag) are low compared to UV-selected AGN at these epochs, consistent with percent-level scattered AGN light or low levels of unobscured star formation, the inferred bolometric luminosities are typical of 107–109M⊙ black holes radiating at ∼10%–40% the Eddington limit. The number densities are surprisingly high at ∼10−5 Mpc−3 mag−1, 100 times more common than the faintest UV-selected quasars, while accounting for ∼1% of the UV-selected galaxies. While their UV faintness suggests they may not contribute strongly to reionization, their ubiquity poses challenges to models of black hole growth.}, author = {Greene, Jenny E. and Labbe, Ivo and Goulding, Andy D. and Furtak, Lukas J. and Chemerynska, Iryna and Kokorev, Vasily and Dayal, Pratika and Volonteri, Marta and Williams, Christina C. and Wang, Bingjie and Setton, David J. and Burgasser, Adam J. and Bezanson, Rachel and Atek, Hakim and Brammer, Gabriel and Cutler, Sam E. and Feldmann, Robert and Fujimoto, Seiji and Glazebrook, Karl and De Graaff, Anna and Khullar, Gourav and Leja, Joel and Marchesini, Danilo and Maseda, Michael V. and Matthee, Jorryt J and Miller, Tim B. and Naidu, Rohan P. and Nanayakkara, Themiya and Oesch, Pascal A. and Pan, Richard and Papovich, Casey and Price, Sedona H. and Van Dokkum, Pieter and Weaver, John R. and Whitaker, Katherine E. and Zitrin, Adi}, issn = {1538-4357}, journal = {Astrophysical Journal}, publisher = {IOP Publishing}, title = {{UNCOVER spectroscopy confirms the surprising ubiquity of active galactic nuclei in red sources at z > 5}}, doi = {10.3847/1538-4357/ad1e5f}, volume = {964}, year = {2024}, } @article{17234, abstract = {The identification of red, apparently massive galaxies at z > 7 in early James Webb Space Telescope (JWST) photometry suggests a strongly accelerated time line compared to standard models of galaxy growth. A major uncertainty in the interpretation is whether the red colors are caused by evolved stellar populations, dust, or other effects such as emission lines or active galactic nuclei (AGNs). Here we show that three of the massive galaxy candidates at z = 6.7–8.4 have prominent Balmer breaks in JWST/NIRSpec spectroscopy from the RUBIES program. The Balmer breaks demonstrate unambiguously that stellar emission dominates at λrest = 0.4 μm and require formation histories extending hundreds of millions of years into the past in galaxies only 600–800 Myr after the big bang. Two of the three galaxies also show broad Balmer lines, with Hβ FWHM > 2500 km s−1, suggesting that dust-reddened AGNs contribute to, or even dominate, the spectral energy distributions of these galaxies at λrest ≳ 0.6 μm. All three galaxies have relatively narrow [O iii] lines, seemingly ruling out a high-mass interpretation if the lines arise in dynamically relaxed, inclined disks. Yet the inferred masses also remain highly uncertain. We model the high-quality spectra using Prospector to decompose the continuum into stellar and AGN components and explore limiting cases in stellar/AGN contribution. This produces a wide range of possible stellar masses, spanning M⋆ ∼ 109−1011M⊙. Nevertheless, all fits suggest a very early and rapid formation, most of which follow with a truncation in star formation. Potential origins and evolutionary tracks for these objects are discussed, from the cores of massive galaxies to low-mass galaxies with overmassive black holes. Intriguingly, we find all of these explanations to be incomplete; deeper and redder data are needed to understand the physics of these systems.}, author = {Wang, Bingjie and Leja, Joel and De Graaff, Anna and Brammer, Gabriel B. and Weibel, Andrea and Van Dokkum, Pieter and Baggen, Josephine F.W. and Suess, Katherine A. and Greene, Jenny E. and Bezanson, Rachel and Cleri, Nikko J. and Hirschmann, Michaela and Labbé, Ivo and Matthee, Jorryt J and Mcconachie, Ian and Naidu, Rohan P. and Nelson, Erica and Oesch, Pascal A. and Setton, David J. and Williams, Christina C.}, issn = {2041-8213}, journal = {Astrophysical Journal Letters}, number = {1}, publisher = {IOP Publishing}, title = {{RUBIES: Evolved stellar populations with extended formation histories at z ∼ 7-8 in candidate massive galaxies identified with JWST/NIRSpec}}, doi = {10.3847/2041-8213/ad55f7}, volume = {969}, year = {2024}, } @article{17889, abstract = {The increasingly neutral intergalactic gas at z > 6 impacts the Lyman-α (Lyα) flux observed from galaxies. One luminous galaxy, COLA1, stands out because of its unique double-peaked Lyα line at z = 6.6, unseen in any simulation of reionization. Here, we present JWST/NIRCam wide-field slitless spectroscopy in a 21 arcmin2 field centered on COLA1. We find 141 galaxies spectroscopically selected through the [O III] doublet at 5.35 < z < 6.95, with 40 of these sources showing Hβ. For COLA1, we additionally detect [O III]4363 as well as Hγ. We measure a systemic redshift of z = 6.5917 for COLA1, confirming the classical double-peak nature of the Lyα profile. This implies that it resides in a highly ionized bubble and that it is leaking ionizing photons with a high escape fraction of fesc(LyC) = 20–50%, making it a prime laboratory to study Lyman continuum escape in the Epoch of Reionization. COLA1 shows all the signs of a prolific ionizer with a Lyα escape fraction of 81 ± 5%, Balmer decrement indicating no dust, a steep UV slope (βUV = −3.2 ± 0.4), and a star-formation surface density ≳10× that of typical galaxies at similar redshift. We detect five galaxies in COLA1’s close environment (Δz < 0.02). Exploiting the high spectroscopic completeness inherent to grism surveys, and using mock simulations that fully mimic the selection function, we show that the number of detected companions is very typical for a normal similarly UV-bright (MUV ∼ −21.3) galaxy – that is, the ionized bubble around COLA1 is unlikely to be due to an excessively large over-density. Instead, the measured ionizing properties suggest that COLA1 by itself might be powering the bubble required to explain its double-peaked Lyα profile (Rion ≈ 0.7 pMpc), with only minor contributions from detected neighbors (−19.5 ≲ MUV ≲ −17.5).}, author = {Torralba-Torregrosa, Alberto and Matthee, Jorryt J and Naidu, Rohan P. and Mackenzie, Ruari and Pezzulli, Gabriele and Hutter, Anne and Arnalte-Mur, Pablo and Gurung-López, Siddhartha and Tacchella, Sandro and Oesch, Pascal and Kashino, Daichi and Conroy, Charlie and Sobral, David}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, publisher = {EDP Sciences}, title = {{Anatomy of an ionized bubble: NIRCam grism spectroscopy of the z = 6.6 double-peaked Lyman- α emitter COLA1 and its environment}}, doi = {10.1051/0004-6361/202450318}, volume = {689}, year = {2024}, } @article{17090, abstract = {Primordial neutral atomic gas, mostly composed of hydrogen, is the raw material for star formation in galaxies. However, there are few direct constraints on the amount of neutral atomic hydrogen (H i) in galaxies at early cosmic times. We analyzed James Webb Space Telescope (JWST) near-infrared spectroscopy of distant galaxies, at redshifts ≳8. From a sample of 12 galaxies, we identified three that show strong damped Lyman-α absorption due to H i in their local surroundings. The galaxies are located at spectroscopic redshifts of 8.8, 10.2, and 11.4, corresponding to 400 to 600 million years after the Big Bang. They have H i column densities ≳1022 cm−2, which is an order of magnitude higher than expected for a fully neutral intergalactic medium, and constitute a gas-rich population of young star-forming galaxies.}, author = {Heintz, Kasper E. and Watson, Darach and Brammer, Gabriel and Vejlgaard, Simone and Hutter, Anne and Strait, Victoria B. and Matthee, Jorryt J and Oesch, Pascal A. and Jakobsson, Páll and Tanvir, Nial R. and Laursen, Peter and Naidu, Rohan P. and Mason, Charlotte A. and Killi, Meghana and Jung, Intae and Hsiao, Tiger Yu Yang and Abdurro’Uf, Unknown and Coe, Dan and Haro, Pablo Arrabal and Finkelstein, Steven L. and Toft, Sune}, issn = {1095-9203}, journal = {Science}, number = {6698}, pages = {890--894}, publisher = {AAAS}, title = {{Strong damped Lyman-a absorption in young star-forming galaxies at redshifts 9 to 11}}, doi = {10.1126/science.adj0343}, volume = {384}, year = {2024}, } @article{15249, abstract = {Observationally mapping the relation between galaxies and the intergalactic medium (IGM) is of key interest for studies of cosmic reionization. Diffuse hydrogen gas has typically been observed in H I Lyman-α (Lyα) absorption in the spectra of bright background quasars. However, it is important to extend these measurements to background galaxies as quasars become increasingly rare at high redshift and rarely probe closely separated sight lines. Here, we use deep integral field spectroscopy in the MUSE eXtremely Deep Field to demonstrate the measurement of the Lyα transmission at z ≈ 4 in absorption to a background galaxy at z = 4.77. The H I transmission is consistent with independent quasar sight lines at similar redshifts. Exploiting the high number of spectroscopic redshifts of faint galaxies (500 between z = 4.0–4.7 within a radius of 8 arcmin) that are tracers of the density field, we show that Lyα transmission is inversely correlated with galaxy density, i.e. transparent regions in the Lyα forest mark underdense regions at z ≈ 4. Due to large-scale clustering, galaxies are surrounded by excess H I absorption over the cosmic mean out to 4 cMpc/h70. We also find that redshifts from the peak of the Lyα line are typically offset from the systemic redshift by +170 km s−1. This work extends results from z ≈ 2–3 to higher redshifts and demonstrates the power of deep integral field spectroscopy to simultaneously measure the ionization structure of the IGM and the large-scale density field in the early Universe.}, author = {Matthee, Jorryt J and Golling, Christopher and Mackenzie, Ruari and Pezzulli, Gabriele and Lilly, Simon and Schaye, Joop and Bacon, Roland and Kusakabe, Haruka and Urrutia, Tanya and Boogaard, Leindert and Brinchmann, Jarle and Maseda, Michael V. and Garel, Thibault and Bouché, Nicolas F. and Wisotzki, Lutz}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {3}, pages = {2794--2806}, publisher = {Oxford University Press}, title = {{Large-scale excess H I absorption around z ≈ 4 galaxies detected in a background galaxy spectrum in the MUSE eXtremely deep field}}, doi = {10.1093/mnras/stae673}, volume = {529}, year = {2024}, } @article{18494, abstract = {We expect luminous (M 1450 ≲ −26.5) high-redshift quasars to trace the highest-density peaks in the early Universe. Here, we present observations of four z ≳ 6 quasar fields using JWST/NIRCam in the imaging and wide-field slitless spectroscopy mode and report a wide range in the number of detected [O iii]-emitting galaxies in the quasars’ environments, ranging between a density enhancement of δ ≈ 65 within a 2 cMpc radius—one of the largest protoclusters during the Epoch of Reionization discovered to date—to a density contrast consistent with zero, indicating the presence of a UV-luminous quasar in a region comparable to the average density of the Universe. By measuring the two-point cross-correlation function of quasars and their surrounding galaxies, as well as the galaxy autocorrelation function, we infer a correlation length of quasars at 〈z〉 = 6.25 of r 0 QQ = 22.0 − 2.9 + 3.0 cMpc h − 1 , while we obtain a correlation length of the [O iii]-emitting galaxies of r 0 GG = 4.1 ± 0.3 cMpc h − 1 . By comparing the correlation functions to dark-matter-only simulations we estimate the minimum mass of the quasars’ host dark matter halos to be log 10 ( M halo , min / M ⊙ ) = 12.43 − 0.15 + 0.13 (and log 10 ( M halo , min [ OIII ] / M ⊙ ) = 10.56 − 0.03 + 0.05 for the [O iii] emitters), indicating that (a) luminous quasars do not necessarily reside within the most overdense regions in the early Universe, and that (b) the UV-luminous duty cycle of quasar activity at these redshifts is f duty ≪ 1. Such short quasar activity timescales challenge our understanding of early supermassive black hole growth and provide evidence for highly dust-obscured growth phases or episodic, radiatively inefficient accretion rates.}, author = {Eilers, Anna Christina and Mackenzie, Ruari and Pizzati, Elia and Matthee, Jorryt J and Hennawi, Joseph F. and Zhang, Haowen and Bordoloi, Rongmon and Kashino, Daichi and Lilly, Simon J. and Naidu, Rohan P. and Simcoe, Robert A. and Yue, Minghao and Frenk, Carlos S. and Helly, John C. and Schaller, Matthieu and Schaye, Joop}, issn = {1538-4357}, journal = {Astrophysical Journal}, number = {2}, publisher = {IOP Publishing}, title = {{EIGER. VI. The correlation function, host halo mass, and duty cycle of luminous quasars at z ≳ 6}}, doi = {10.3847/1538-4357/ad778b}, volume = {974}, year = {2024}, } @article{18447, abstract = {We present the first results on the spatial distribution of star formation in 454 star-forming galaxies just after the epoch of reionisation (4.8 < z < 6.5) using Hα emission-line maps and F444W imaging that traces the stellar continuum from the JWST FRESCO NIRCam Slitless Spectroscopy Survey. The Hα equivalent width profiles of star-forming galaxies across the main sequence at z ∼ 5.3 with stellar masses 6.8≤ log(M*/M⊙) < 11.1 increase with radius, which provides direct evidence for the inside-out growth of star-forming galaxies just after the epoch of reionisation. GALFIT was used to calculate half-light radii, Reff, and central surface densities within 1 kiloparsec, Σ1kpc of Hα and the continuum. At a fixed stellar mass of Log(M*/M⊙) = 9.5, Σ1kpc, Hα is 1.04 ± 0.05 times higher than Σ1kpc, C, Reff, Hα is 1.18 ± 0.03 times larger than Reff, C and both Reff measurements are smaller than 1 kiloparsec. These measurements suggest the rapid build-up of compact bulges via star formation just after the epoch of reionisation. By comparison to analogous work done at lower redshifts with Hubble Space Telescope WFC3 slitless spectroscopy as part of the 3D-HST (z ∼ 1) and CLEAR (z ∼ 0.5) surveys, we find that Reff(z) evolves at the same pace for Hα and the continuum, but Σ1kpc(z) evolves faster for Hα than the stellar continuum. As a function of the Hubble parameter, Reff, Hα/Reff,C = 1.1h(z) and Σ1 kpc, Hα/Σ1 kpc,C = h(z)1.3. These parametrisations suggest that the inside-out growth of the disk starts to dominate the inside-out growth of the bulge towards lower redshifts. This is supported by the redshift evolution in the EW(Hα) profiles from FRESCO, 3D-HST, and CLEAR at fixed stellar mass and when star-forming progenitors are traced, in which in EW(Hα) rapidly increases with radius within the half-light radius at z ∼ 5.3, but EW(Hα) increases only significantly with radius in the outer disk at z ∼ 0.5.}, author = {Matharu, Jasleen and Nelson, Erica J. and Brammer, Gabriel and Oesch, Pascal A. and Allen, Natalie and Shivaei, Irene and Naidu, Rohan P. and Chisholm, John and Covelo-Paz, Alba and Fudamoto, Yoshinobu and Giovinazzo, Emma and Herard-Demanche, Thomas and Kerutt, Josephine and Kramarenko, Ivan and Marchesini, Danilo and Meyer, Romain A. and Prieto-Lyon, Gonzalo and Reddy, Naveen and Shuntov, Marko and Weibel, Andrea and Wuyts, Stijn and Xiao, Mengyuan}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, publisher = {EDP Sciences}, title = {{A first look at spatially resolved star formation at 4.8 < z < 6.5 with JWST FRESCO NIRCam slitless spectroscopy}}, doi = {10.1051/0004-6361/202450522}, volume = {690}, year = {2024}, } @article{15336, abstract = {Submillimeter surveys toward overdense regions in the early Universe are essential for uncovering the obscured star formation and the cold gas content of assembling galaxies within massive dark matter halos. In this work, we present deep ALMA mosaic observations covering an area of ∼2′×2′ around MUSE Quasar Nebula 01 (MQN01), one of the largest and brightest Ly-α emitting nebulae discovered thus far; it surrounds a radio-quiet quasar at z ≃ 3.25. Our observations target the 1.2 and the 3 mm dust continuum as well as the carbon monoxide CO(4–3) transition in galaxies in the vicinity of the quasar. We identify a robust sample of 11 CO-line-emitting galaxies (including a closely separated quasar companion) that lie within ±4000 km s−1 of the quasar systemic redshift. A fraction of these objects were missed in previous deep rest-frame optical/UV surveys, which highlights the critical role of (sub)millimeter imaging. We also detect a total of 11 sources revealed in the dust continuum at 1.2 mm; six of them have either high-fidelity spectroscopic redshift information from rest-frame UV metal absorptions or the CO(4–3) line that places them in the same narrow redshift range. A comparison of the CO luminosity function and 1.2 mm number count density with those of the general fields points to a galaxy overdensity of δ > 10. We find evidence of a systematic flattening at the bright end of the CO luminosity function with respect to the trend measured in blank fields. Our findings reveal that galaxies in dense regions at z ∼ 3 are more massive and significantly richer in molecular gas than galaxies in fields, which enables a faster and accelerated assembly. This is the first in a series of studies aimed at characterizing one of the densest regions of the Universe found so far at z > 3.}, author = {Pensabene, A. and Cantalupo, S. and Cicone, C. and Decarli, R. and Galbiati, M. and Ginolfi, M. and De Beer, S. and Fossati, M. and Fumagalli, M. and Lazeyras, T. and Pezzulli, G. and Travascio, A. and Wang, W. and Matthee, Jorryt J and Maseda, M. V.}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, publisher = {EDP Sciences}, title = {{ALMA survey of a massive node of the Cosmic Web at z ∼ 3: I. Discovery of a large overdensity of CO emitters}}, doi = {10.1051/0004-6361/202348659}, volume = {684}, year = {2024}, } @article{18069, abstract = {We present results from the JWST First Reionization Epoch Spectroscopically Complete Observations survey on the star-forming sequence (SFS) of galaxies at 1.0 < z < 1.7, around the peak of the cosmic star formation history. Star formation rates (SFRs) are measured from the redshifted, relatively dust-insensitive Paschen-α emission line, and stellar mass measurements include the F444W (4.4 μm; rest-frame H) band. We find SFRs of galaxies with log(M*/M⊙) > 9.5 that are lower than found in many earlier studies by up to 0.6 dex, but in good agreement with recent results obtained with the Prospector fitting framework. The difference (log(SFR(Paα)-SFR(Prospector)) is −0.09 ± 0.04 dex at 1010−11M⊙. We also measure the empirical relation between Paschen-α luminosity and rest-frame H-band magnitude and find that the scatter is only 0.04 dex lower than that of the SFR–M* relation and is much lower than the systematic differences among relations in the literature due to various methods of converting observed measurements to physical properties. We additionally identify examples of sources—that, with standard cutoffs via the UVJ diagram, would be deemed quiescent—with significant (log(sSFR)> −11 yr−1), typically extended, Paschen-α emission. Our results may be indicative of the potential unification of methods used to derive the SFS with careful selection of star-forming galaxies and independent SFR and stellar mass indicators.}, author = {Neufeld, Chloe and Van Dokkum, Pieter and Asali, Yasmeen and Covelo-Paz, Alba and Leja, Joel and Lin, Jamie and Matthee, Jorryt J and Oesch, Pascal A. and Reddy, Naveen A. and Shivaei, Irene and Whitaker, Katherine E. and Wuyts, Stijn and Brammer, Gabriel and Marchesini, Danilo and Maseda, Michael V. and Naidu, Rohan P. and Nelson, Erica J. and Velichko, Anna and Weibel, Andrea and Xiao, Mengyuan}, issn = {1538-4357}, journal = {Astrophysical Journal}, number = {2}, publisher = {IOP Publishing}, title = {{FRESCO: The Paschen-α star-forming sequence at cosmic noon}}, doi = {10.3847/1538-4357/ad6158}, volume = {972}, year = {2024}, }