@article{14826, abstract = {The plant-signaling molecule auxin triggers fast and slow cellular responses across land plants and algae. The nuclear auxin pathway mediates gene expression and controls growth and development in land plants, but this pathway is absent from algal sister groups. Several components of rapid responses have been identified in Arabidopsis, but it is unknown if these are part of a conserved mechanism. We recently identified a fast, proteome-wide phosphorylation response to auxin. Here, we show that this response occurs across 5 land plant and algal species and converges on a core group of shared targets. We found conserved rapid physiological responses to auxin in the same species and identified rapidly accelerated fibrosarcoma (RAF)-like protein kinases as central mediators of auxin-triggered phosphorylation across species. Genetic analysis connects this kinase to both auxin-triggered protein phosphorylation and rapid cellular response, thus identifying an ancient mechanism for fast auxin responses in the green lineage.}, author = {Kuhn, Andre and Roosjen, Mark and Mutte, Sumanth and Dubey, Shiv Mani and Carrillo Carrasco, Vanessa Polet and Boeren, Sjef and Monzer, Aline and Koehorst, Jasper and Kohchi, Takayuki and Nishihama, Ryuichi and Fendrych, Matyas and Sprakel, Joris and Friml, Jiří and Weijers, Dolf}, issn = {1097-4172}, journal = {Cell}, keywords = {General Biochemistry, Genetics and Molecular Biology}, number = {1}, pages = {130--148.e17}, publisher = {Elsevier}, title = {{RAF-like protein kinases mediate a deeply conserved, rapid auxin response}}, doi = {10.1016/j.cell.2023.11.021}, volume = {187}, year = {2024}, } @article{15319, abstract = {Exocyst component of 70-kDa (EXO70) proteins are constituents of the exocyst complex implicated in vesicle tethering during exocytosis. MILDEW RESISTANCE LOCUS O (MLO) proteins are plant-specific calcium channels and some MLO isoforms enable fungal powdery mildew pathogenesis. We here detected an unexpected phenotypic overlap of Arabidopsis thaliana exo70H4 and mlo2 mlo6 mlo12 triple mutant plants regarding the biogenesis of leaf trichome secondary cell walls. Biochemical and Fourier transform infrared spectroscopic analyses corroborated deficiencies in the composition of trichome cell walls in these mutants. Transgenic lines expressing fluorophore-tagged EXO70H4 and MLO exhibited extensive colocalization of these proteins. Furthermore, mCherry-EXO70H4 mislocalized in trichomes of the mlo triple mutant and, vice versa, MLO6-GFP mislocalized in trichomes of the exo70H4 mutant. Expression of GFP-marked PMR4 callose synthase, a known cargo of EXO70H4-dependent exocytosis, revealed reduced cell wall delivery of GFP-PMR4 in trichomes of mlo triple mutant plants. In vivo protein–protein interaction assays in plant and yeast cells uncovered isoform-preferential interactions between EXO70.2 subfamily members and MLO proteins. Finally, exo70H4 and mlo6 mutants, when combined, showed synergistically enhanced resistance to powdery mildew attack. Taken together, our data point to an isoform-specific interplay of EXO70 and MLO proteins in the modulation of trichome cell wall biogenesis and powdery mildew susceptibility.}, author = {Huebbers, Jan W. and Caldarescu, George A. and Kubátová, Zdeňka and Sabol, Peter and Levecque, Sophie C.J. and Kuhn, Hannah and Kulich, Ivan and Reinstädler, Anja and Büttgen, Kim and Manga-Robles, Alba and Mélida, Hugo and Pauly, Markus and Panstruga, Ralph and Žárský, Viktor}, issn = {1532-298X}, journal = {Plant Cell}, number = {4}, pages = {1007--1035}, publisher = {Oxford University Press}, title = {{Interplay of EXO70 and MLO proteins modulates trichome cell wall composition and susceptibility to powdery mildew}}, doi = {10.1093/plcell/koad319}, volume = {36}, year = {2024}, } @article{17436, abstract = {The auxin signaling molecule controls a variety of growth and developmental processes in land plants. Auxin regulates gene expression through a nuclear auxin signaling pathway (NAP) consisting of the ubiquitin ligase auxin receptor TIR1/AFB, its Aux/IAA degradation substrate, and DNA-binding ARF transcription factors. Although extensive qualitative understanding of the pathway and its interactions has been obtained, mostly by studying the flowering plant Arabidopsis thaliana, it remains unknown how these translate to quantitative system behavior in vivo, a problem that is confounded by the large NAP gene families in most species. Here, we used the minimal NAP of the liverwort Marchantia polymorpha to quantitatively map NAP protein accumulation and dynamics in vivo through the use of knockin fluorescent fusion proteins. Beyond revealing the dynamic native accumulation profile of the entire NAP protein network, we discovered that the two central ARFs, MpARF1 and MpARF2, are proteasomally degraded. This auxin-independent degradation tunes ARF protein stoichiometry to favor gene activation, thereby reprogramming auxin response during the developmental progression. Thus, quantitative analysis of the entire NAP has enabled us to identify ARF degradation and the stoichiometries of activator and repressor ARFs as a potential mechanism for controlling gemma germination.}, author = {Das, Shubhajit and De Roij, Martijn and Bellows, Simon and Alvarez, Melissa Dipp and Mutte, Sumanth and Kohlen, Wouter and Farcot, Etienne and Weijers, Dolf and Borst, Jan Willem}, issn = {2590-3462}, journal = {Plant Communications}, number = {11}, publisher = {Elsevier}, title = {{Quantitative imaging reveals the role of MpARF proteasomal degradation during gemma germination}}, doi = {10.1016/j.xplc.2024.101039}, volume = {5}, year = {2024}, } @article{18465, abstract = {The phytohormone auxin is polarly transported in plants by PIN-FORMED (PIN) transporters and controls virtually all growth and developmental processes. Canonical PINs possess a long, largely disordered cytosolic loop. Auxin transport by canonical PINs is activated by loop phosphorylation by certain kinases. The structure of the PIN transmembrane domains was recently determined, their transport properties remained poorly characterized, and the role of the loop in the transport process was unclear. Here, we determined the quantitative kinetic parameters of auxin transport mediated by Arabidopsis PINs to mathematically model auxin distribution in roots and to test these predictions in vivo. Using chimeras between transmembrane and loop domains of different PINs, we demonstrate a strong correlation between transport parameters and physiological output, indicating that the loop domain is not only required to activate PIN-mediated auxin transport, but it has an additional role in the transport process by a currently unknown mechanism.}, author = {Janacek, DP and Kolb, M and Schulz, L and Mergner, J and Kuster, B and Glanc, Matous and Friml, Jiří and Ten Tusscher, K and Schwechheimer, C and Hammes, UZ}, issn = {1878-1551}, journal = {Developmental Cell}, number = {14}, pages = {S1534--5807(24)00569--0}, publisher = {Elsevier}, title = {{Transport properties of canonical PIN-FORMED proteins from Arabidopsis and the role of the loop domain in auxin transport}}, doi = {10.1016/j.devcel.2024.09.020}, volume = {59}, year = {2024}, } @article{18582, abstract = {Identification of PIN exporters for auxin, the major coordinative signal in plants, some 25 years ago, signifies a landmark in our understanding of plant-specific mechanisms underlying development and adaptation. Auxin is directionally transported throughout the plant body; a unique feature already envisioned by Darwin and solidified by PINs’ discovery and characterization. The PIN-based auxin distribution network with its complex regulations of PIN expression, localization and activity turned out to underlie a remarkable multitude of developmental processes and represents means to integrate endogenous and environmental signals. Given the recent anniversary, we here summarize past and current developments in this exciting field.}, author = {Luschnig, Christian and Friml, Jiří}, issn = {2041-1723}, journal = {Nature Communications}, publisher = {Springer Nature}, title = {{Over 25 years of decrypting PIN-mediated plant development}}, doi = {10.1038/s41467-024-54240-y}, volume = {15}, year = {2024}, } @article{15251, abstract = {Brassinosteroids are steroidal phytohormones that regulate plant development and physiology, including adaptation to environmental stresses. Brassinosteroids are synthesized in the cell interior but bind receptors at the cell surface, necessitating a yet to be identified export mechanism. Here, we show that a member of the ATP-binding cassette (ABC) transporter superfamily, ABCB19, functions as a brassinosteroid exporter. We present its structure in both the substrate-unbound and the brassinosteroid-bound states. Bioactive brassinosteroids are potent activators of ABCB19 ATP hydrolysis activity, and transport assays showed that ABCB19 transports brassinosteroids. In Arabidopsis thaliana, ABCB19 and its close homolog, ABCB1, positively regulate brassinosteroid responses. Our results uncover an elusive export mechanism for bioactive brassinosteroids that is tightly coordinated with brassinosteroid signaling.}, author = {Ying, Wei and Wang, Yaowei and Wei, Hong and Luo, Yongming and Ma, Qian and Zhu, Heyuan and Janssens, Hilde and Vukašinović, Nemanja and Kvasnica, Miroslav and Winne, Johan M. and Gao, Yongxiang and Tan, Shutang and Friml, Jiří and Liu, Xin and Russinova, Eugenia and Sun, Linfeng}, issn = {1095-9203}, journal = {Science}, number = {6689}, pages = {eadj4591}, publisher = {American Association for the Advancement of Science}, title = {{Structure and function of the Arabidopsis ABC transporter ABCB19 in brassinosteroid export}}, doi = {10.1126/science.adj4591}, volume = {383}, year = {2024}, } @article{17377, abstract = {Lateral root (LR) formation, that is vital for plant development, is one of many auxin-modulated processes, but the underlying regulatory mechanism is not yet fully known. Recently, González-García et al. discovered the BiAux compound and showed that it is involved in LR development via regulating specific auxin coreceptors.}, author = {Wójcikowska, Barbara and Friml, Jiří and Mazur, Ewa}, issn = {1360-1385}, journal = {Trends in Plant Science}, number = {12}, pages = {1279--1281}, publisher = {Elsevier}, title = {{BiAux, a newly discovered compound triggering auxin signaling}}, doi = {10.1016/j.tplants.2024.07.008}, volume = {29}, year = {2024}, } @inbook{15361, abstract = {Bimolecular fluorescence complementation (BiFC) is a powerful tool for studying protein-protein interactions in living cells. By fusing interacting proteins to fluorescent protein fragments, BiFC allows visualization of spatial localization patterns of protein complexes. This method has been adapted to a variety of expression systems in different organisms and is widely used to study protein interactions in plant cells. The Agrobacterium-mediated transient expression protocol for BiFC assays in Nicotiana benthamiana (N. benthamiana) leaf cells is widely used, but in this chapter, a method for BiFC assay using Arabidopsis thaliana protoplasts is presented.}, author = {Jayasree, Aswathy and Salava, Hymavathi and Nodzynski, Tomasz and Sravankumar, Thula}, booktitle = {Plant Functional Genomics}, editor = {Maghuly, Fatemeh}, isbn = {9781071637777}, issn = {1940-6029}, pages = {305--313}, publisher = {Springer Nature}, title = {{Protein-Protein Interactions Visualized by Bimolecular Fluorescence Complementation in Arabidopsis thaliana Protoplasts from Leaf}}, doi = {10.1007/978-1-0716-3778-4_21}, volume = {2787}, year = {2024}, } @article{18311, abstract = {Local wound signaling in plants informs the surrounding tissues about an injury and initiates the regeneration process. In a recent paper published in Cell, Yang and colleagues show the involvement of a single Pep family member from tomato in wound signaling and how exogenous application of this regeneration factor enhances transformation efficiency in crops.}, author = {Hörmayer, Lukas and Friml, Jiří}, issn = {1748-7838}, journal = {Cell Research}, pages = {761--762}, publisher = {Springer Nature}, title = {{Feeling the danger: Local wound signaling in plants}}, doi = {10.1038/s41422-024-01035-x}, volume = {34}, year = {2024}, } @article{15257, abstract = {Root gravitropic bending represents a fundamental aspect of terrestrial plant physiology. Gravity is perceived by sedimentation of starch-rich plastids (statoliths) to the bottom of the central root cap cells. Following gravity perception, intercellular auxin transport is redirected downwards leading to an asymmetric auxin accumulation at the lower root side causing inhibition of cell expansion, ultimately resulting in downwards bending. How gravity-induced statoliths repositioning is translated into asymmetric auxin distribution remains unclear despite PIN auxin efflux carriers and the Negative Gravitropic Response of roots (NGR) proteins polarize along statolith sedimentation, thus providing a plausible mechanism for auxin flow redirection. In this study, using a functional NGR1-GFP construct, we visualized the NGR1 localization on the statolith surface and plasma membrane (PM) domains in close proximity to the statoliths, correlating with their movements. We determined that NGR1 binding to these PM domains is indispensable for NGR1 functionality and relies on cysteine acylation and adjacent polybasic regions as well as on lipid and sterol PM composition. Detailed timing of the early events following graviperception suggested that both NGR1 repolarization and initial auxin asymmetry precede the visible PIN3 polarization. This discrepancy motivated us to unveil a rapid, NGR-dependent translocation of PIN-activating AGCVIII kinase D6PK towards lower PMs of gravity-perceiving cells, thus providing an attractive model for rapid redirection of auxin fluxes following gravistimulation.}, author = {Kulich, Ivan and Schmid, Julia and Teplova, Anastasiia and Qi, Linlin and Friml, Jiří}, issn = {2050-084X}, journal = {eLife}, keywords = {General Immunology and Microbiology, General Biochemistry, Genetics and Molecular Biology, General Medicine, General Neuroscience}, publisher = {eLife Sciences Publications}, title = {{Rapid translocation of NGR proteins driving polarization of PIN-activating D6 protein kinase during root gravitropism}}, doi = {10.7554/elife.91523}, volume = {12}, year = {2024}, } @article{15301, abstract = {Plant morphogenesis relies exclusively on oriented cell expansion and division. Nonetheless, the mechanism(s) determining division plane orientation remain elusive. Here, we studied tissue healing after laser-assisted wounding in roots of Arabidopsis thaliana and uncovered how mechanical forces stabilize and reorient the microtubule cytoskeleton for the orientation of cell division. We identified that root tissue functions as an interconnected cell matrix, with a radial gradient of tissue extendibility causing predictable tissue deformation after wounding. This deformation causes instant redirection of expansion in the surrounding cells and reorientation of microtubule arrays, ultimately predicting cell division orientation. Microtubules are destabilized under low tension, whereas stretching of cells, either through wounding or external aspiration, immediately induces their polymerization. The higher microtubule abundance in the stretched cell parts leads to the reorientation of microtubule arrays and, ultimately, informs cell division planes. This provides a long-sought mechanism for flexible re-arrangement of cell divisions by mechanical forces for tissue reconstruction and plant architecture.}, author = {Hörmayer, Lukas and Montesinos López, Juan C and Trozzi, N and Spona, Leonhard and Yoshida, Saiko and Marhavá, Petra and Caballero Mancebo, Silvia and Benková, Eva and Heisenberg, Carl-Philipp J and Dagdas, Y and Majda, M and Friml, Jiří}, issn = {1878-1551}, journal = {Developmental Cell}, number = {10}, pages = {1333--1344.e4}, publisher = {Elsevier}, title = {{Mechanical forces in plant tissue matrix orient cell divisions via microtubule stabilization}}, doi = {10.1016/j.devcel.2024.03.009}, volume = {59}, year = {2024}, } @article{18596, abstract = {Hormone perception and signaling pathways have a fundamental regulatory function in the physiological processes of plants. Cytokinins, a class of plant hormones, regulate cell division and meristem maintenance. The cytokinin signaling pathway is well established in the model plant Arabidopsis thaliana. Several negative feedback mechanisms, tightly controlling cytokinin signaling output, have been described previously. In this study, we identified a new feedback mechanism executed through alternative splicing of the cytokinin receptor AHK4/CRE1. A novel splicing variant named CRE1int7 results from seventh intron retention, introducing a premature termination codon in the transcript. We showed that CRE1int7 is translated in planta into a truncated receptor lacking the C-terminal receiver domain essential for signal transduction. CRE1int7 can bind cytokinin but cannot activate the downstream cascade. We present a novel negative feedback mechanism of the cytokinin signaling pathway, facilitated by a decoy receptor that can inactivate canonical cytokinin receptors via dimerization and compete with them for ligand binding. Ensuring proper plant growth and development requires precise control of the cytokinin signaling pathway at several levels. CRE1int7 represents a so-far unknown mechanism for fine-tuning the cytokinin signaling pathway in Arabidopsis.}, author = {Králová, Michaela and Kubalová, Ivona and Hajný, Jakub and Kubiasova, Karolina and Vagaská, Karolína and Ge, Zengxiang and Gallei, Michelle C and Semerádová, Hana and Kuchařová, Anna and Hönig, Martin and Monzer, Aline and Kovačik, Martin and Friml, Jiří and Novák, Ondřej and Benková, Eva and Ikeda, Yoshihisa and Zalabák, David}, issn = {1674-2052}, journal = {Molecular Plant}, number = {12}, pages = {1850--1865}, publisher = {Elsevier}, title = {{A decoy receptor derived from alternative splicing fine-tunes cytokinin signaling in Arabidopsis}}, doi = {10.1016/j.molp.2024.11.001}, volume = {17}, year = {2024}, } @article{15381, abstract = {Cholecystokinin-expressing interneurons (CCKIs) are hypothesized to shape pyramidal cell-firing patterns and regulate network oscillations and related network state transitions. To directly probe their role in the CA1 region, we silenced their activity using optogenetic and chemogenetic tools in mice. Opto-tagged CCKIs revealed a heterogeneous population, and their optogenetic silencing triggered wide disinhibitory network changes affecting both pyramidal cells and other interneurons. CCKI silencing enhanced pyramidal cell burst firing and altered the temporal coding of place cells: theta phase precession was disrupted, whereas sequence reactivation was enhanced. Chemogenetic CCKI silencing did not alter the acquisition of spatial reference memories on the Morris water maze but enhanced the recall of contextual fear memories and enabled selective recall when similar environments were tested. This work suggests the key involvement of CCKIs in the control of place-cell temporal coding and the formation of contextual memories.}, author = {Rangel Guerrero, Dámaris K and Balueva, Kira and Barayeu, Uladzislau and Baracskay, Peter and Gridchyn, Igor and Nardin, Michele and Roth, Chiara N and Wulff, Peer and Csicsvari, Jozsef L}, issn = {1097-4199}, journal = {Neuron}, number = {12}, pages = {2045--2061.e10}, publisher = {Cell Press}, title = {{Hippocampal cholecystokinin-expressing interneurons regulate temporal coding and contextual learning}}, doi = {10.1016/j.neuron.2024.03.019}, volume = {112}, year = {2024}, } @article{17477, abstract = {Trapped-ion systems are a leading platform for quantum information processing, but they are currently limited to 1D and 2D arrays, which imposes restrictions on both their scalability and their range of applications. Here, we propose a path to overcome this limitation by demonstrating that Penning traps can be used to realize remarkably clean bilayer crystals, wherein hundreds of ions self-organize into two well-defined layers. These bilayer crystals are made possible by the inclusion of an anharmonic trapping potential, which is readily implementable with current technology. We study the normal modes of this system and discover salient differences compared to the modes of single-plane crystals. The bilayer geometry and the unique properties of the normal modes open new opportunities—in particular, in quantum sensing and quantum simulation—that are not straightforward in single-plane crystals. Furthermore, we illustrate that it may be possible to extend the ideas presented here to realize multilayer crystals with more than two layers. Our work increases the dimensionality of trapped-ion systems by efficiently utilizing all three spatial dimensions, and it lays the foundation for a new generation of quantum information processing experiments with multilayer 3D crystals of trapped ions.}, author = {Hawaldar, Samarth and Shahi, Prakriti and Carter, Allison L. and Rey, Ana Maria and Bollinger, John J. and Shankar, Athreya}, issn = {2160-3308}, journal = {Physical Review X}, number = {3}, publisher = {American Physical Society}, title = {{Bilayer crystals of trapped ions for quantum information processing}}, doi = {10.1103/PhysRevX.14.031030}, volume = {14}, year = {2024}, } @article{17089, abstract = {How the coordination of neuronal spiking and brain rhythms between hippocampal subregions supports memory function remains elusive. We studied the interregional coordination of CA3 neuronal spiking with CA1 theta oscillations by recording electrophysiological signals along the proximodistal axis of the hippocampus in rats that were performing a high-memory-demand recognition memory task adapted from humans. We found that CA3 population spiking occurs preferentially at the peak of distal CA1 theta oscillations when memory was tested but only when previously encountered stimuli were presented. In addition, decoding analyses revealed that only population cell firing of proximal CA3 together with that of distal CA1 can predict performance at test in the present non-spatial task. Overall, our work demonstrates an important role for the synchronization of CA3 neuronal activity with CA1 theta oscillations during memory testing.}, author = {Ku, Shih Pi and Atucha, Erika and Alavi, Nico and Mulla-Osman, Halla and Kayumova, Rukhshona and Yoshida, Motoharu and Csicsvari, Jozsef L and Sauvage, Magdalena M.}, issn = {2211-1247}, journal = {Cell Reports}, number = {6}, publisher = {Elsevier}, title = {{Phase locking of hippocampal CA3 neurons to distal CA1 theta oscillations selectively predicts memory performance}}, doi = {10.1016/j.celrep.2024.114276}, volume = {43}, year = {2024}, } @article{17410, abstract = {We present a cavity-electromechanical system comprising a superconducting quantum interference device which is embedded in a microwave resonator and coupled via a pickup loop to a 6-μ⁢g magnetically levitated superconducting sphere. The motion of the sphere in the magnetic trap induces a frequency shift in the SQUID-cavity system. We use microwave spectroscopy to characterize the system, and we demonstrate that the electromechanical interaction is tunable. The measured displacement sensitivity of 10−7m/√Hz defines a path towards ground-state cooling of levitated particles with Planck-scale masses at millikelvin environment temperatures.}, author = {Schmidt, Philip and Claessen, Remi and Higgins, Gerard and Hofer, Joachim and Hansen, Jannek J. and Asenbaum, Peter and Zemlicka, Martin and Uhl, Kevin and Kleiner, Reinhold and Gross, Rudolf and Huebl, Hans and Trupke, Michael and Aspelmeyer, Markus}, issn = {2331-7019}, journal = {Physical Review Applied}, publisher = {American Physical Society}, title = {{Remote sensing of a levitated superconductor with a flux-tunable microwave cavity}}, doi = {10.1103/PhysRevApplied.22.014078}, volume = {22}, 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}, }