An optimal ALMA image of the Hubble Ultra Deep Field in the era of JWST: obscured star formation and the cosmic far-infrared background

We combine archival ALMA data targeting the Hubble Ultra Deep Field (HUDF) to produce the deepest currently attainable 1-mm maps of this key, extragalactic survey field. Combining all existing data in Band 6, our deepest map covers 4.2arcmin^2, with a beamsize of 1.49"x1.07" at an effective frequency of 243GHz (1.23mm). It reaches an rms of 4.6uJy/beam, with 1.5arcmin^2 below 9.0uJy/beam, an improvement of >5% over the best previously published map and 50% improvement in some regions. We also make a wider, but shallower map, covering 25.4arcmin^2. We detect 45 galaxies in the deep map down to 3.6sigma, including 10 more 1-mm sources than previously detected. 38 of these galaxies have a JWST ID from the JADES NIRCam imaging and the new sources are typically faint and red. A stacking analysis on the positions of ALMA-undetected JADES galaxies yields detections for z<4 and stellar masses from 10^(8.4) to 10^(10.4)Msun, extracting 10% of additional stacked signal from our map compared to previous analyses. Detected sources and stacking contribute (10.0+/-0.5)Jy/deg^2 of the cosmic infrared background (CIB) at 1.23mm. Although this is short of the (uncertain) background level of about 20Jy/deg^2, after taking into account intrinsic fluctuations in the CIB, our measurement is consistent with the background if the HUDF is a mild (~2sigma) negative fluctuation. This suggests that within the HUDF, JWST may have detected essentially all of the galaxies that contribute to the CIB. Our stacking analysis predicts that the field contains around 60 additional galaxies with 1.23mm flux densities averaging around 15uJy, and over 300 galaxies at the few uJy level. However, the contribution of these fainter more modestly-obscured objects to the background is small, and converging, as anticipated from the now well-established strong correlation between galaxy stellar mass and obscured star formation.Comment: Submitted to MNRA

Accounting for Cosmic Variance in Studies of Gravitationally-Lensed High-Redshift Galaxies in the Hubble Frontier Field Clusters

Strong gravitational lensing provides a powerful means for studying faint galaxies in the distant universe. By magnifying the apparent brightness of background sources, massive clusters enable the detection of galaxies fainter than the usual sensitivity limit for blank fields. However, this gain in effective sensitivity comes at the cost of a reduced survey volume and, in this {\it Letter}, we demonstrate there is an associated increase in the cosmic variance uncertainty. As an example, we show that the cosmic variance uncertainty of the high redshift population viewed through the Hubble Space Telescope Frontier Field cluster Abell 2744 increases from ~35% at redshift z~7 to >~65% at z~10. Previous studies of high redshift galaxies identified in the Frontier Fields have underestimated the cosmic variance uncertainty that will affect the ultimate constraints on both the faint end slope of the high-redshift luminosity function and the cosmic star formation rate density, key goals of the Frontier Field program.Comment: 5 pages, 3 figures. Version accepted by ApJ

A massive quiescent galaxy at redshift 4.658

A. C. Carnall thanks the Leverhulme Trust for their support via a Leverhulme Early Career Fellowship. R. J. McLure, J. S. Dunlop, D. J. McLeod, V. Wild, R. Begley, C. T. Donnan and M. L. Hamadouche acknowledge the support of the Science and Technology Facilities Council. F. Cullen acknowledges support from a UKRI Frontier Research Guarantee Grant (grant reference EP/X021025/1). A. Cimatti acknowledges support from the grant PRIN MIUR 2017 - 20173ML3WW 001.The extremely rapid assembly of the earliest galaxies during the first billion years of cosmic history is a major challenge for our understanding of galaxy formation physics (1; 2; 3; 4; 5). The advent of JWST has exacerbated this issue by confirming the existence of galaxies in significant numbers as early as the first few hundred million years (6; 7; 8). Perhaps even more surprisingly, in some galaxies, this initial highly efficient star formation rapidly shuts down, or quenches, giving rise to massive quiescent galaxies as little as 1.5 billion years after the Big Bang (9; 10), however, due to their faintness and red colour, it has proven extremely challenging to learn about these extreme quiescent galaxies, or to confirm whether any exist at earlier times. Here we report the spectroscopic confirmation of a massive quiescent galaxy, GS-9209, at redshift, z = 4.658, just 1.25 billion years after the Big Bang, using JWST NIRSpec. From these data we infer a stellar mass of M∗ = 3.8 ± 0.2 × 1010 M⊙, which formed over a ≃ 200 Myr period before this galaxy quenched its star formation activity at z=6.5+0.2−0.5, when the Universe was ≃ 800 million years old. This galaxy is both a likely descendent of the highest-redshift submillimetre galaxies and quasars, and a likely progenitor for the dense, ancient cores of the most massive local galaxies.PostprintPeer reviewe

Survey of the quality of experimental design, statistical analysis and reporting of research using animals

For scientific, ethical and economic reasons, experiments involving animals should be appropriately designed, correctly analysed and transparently reported. This increases the scientific validity of the results, and maximises the knowledge gained from each experiment. A minimum amount of relevant information must be included in scientific publications to ensure that the methods and results of a study can be reviewed, analysed and repeated. Omitting essential information can raise scientific and ethical concerns. We report the findings of a systematic survey of reporting, experimental design and statistical analysis in published biomedical research using laboratory animals. Medline and EMBASE were searched for studies reporting research on live rats, mice and non-human primates carried out in UK and US publicly funded research establishments. Detailed information was collected from 271 publications, about the objective or hypothesis of the study, the number, sex, age and/or weight of animals used, and experimental and statistical methods. Only 59% of the studies stated the hypothesis or objective of the study and the number and characteristics of the animals used. Appropriate and efficient experimental design is a critical component of high-quality science. Most of the papers surveyed did not use randomisation (87%) or blinding (86%), to reduce bias in animal selection and outcome assessment. Only 70% of the publications that used statistical methods described their methods and presented the results with a measure of error or variability. This survey has identified a number of issues that need to be addressed in order to improve experimental design and reporting in publications describing research using animals. Scientific publication is a powerful and important source of information; the authors of scientific publications therefore have a responsibility to describe their methods and results comprehensively, accurately and transparently, and peer reviewers and journal editors share the responsibility to ensure that published studies fulfil these criteria

The stellar metallicities of massive quiescent galaxies at 1.0 &lt; z &lt; 1.3 from KMOS+VANDELS

We present a rest-frame UV-optical stacked spectrum representative of massive quiescent galaxies at $1.010.8$. The stack is constructed using VANDELS survey data, combined with new KMOS observations. We apply two independent full-spectral-fitting approaches, measuring a total metallicity, [Z/H]=$-0.13\pm0.08$ with Bagpipes, and [Z/H]=$0.04\pm0.14$ with Alf, a fall of $\sim0.2-0.3$ dex compared with the local Universe. We also measure an iron abundance, [Fe/H] =$-0.18\pm0.08$, a fall of $\sim0.15$ dex compared with the the local Universe. We measure the alpha enhancement via the magnesium abundance, obtaining [Mg/Fe]=$0.23\pm$0.12, consistent with similar-mass galaxies in the local Universe, indicating no evolution in the average alpha enhancement of log$(M_*/\rm{M_\odot})=11$ quiescent galaxies over the last $\sim8$ Gyr. This suggests the very high alpha enhancements recently reported for several bright $z\sim1-2$ quiescent galaxies are due to their extreme masses, log$(M_*/\rm{M_\odot})\gtrsim11.5$, rather than being typical of the $z\gtrsim1$ population. The metallicity evolution we observe with redshift (falling [Z/H], [Fe/H], constant [Mg/Fe]) is consistent with recent studies. We recover a mean stellar age of $2.5^{+0.6}_{-0.4}$ Gyr, corresponding to a formation redshift, z_\rm{form}=2.4^{+0.6}_{-0.3}. Recent studies have obtained varying average formation redshifts for $z\gtrsim1$ massive quiescent galaxies, and, as these studies report consistent metallicities, we identify different star-formation-history models as the most likely cause. Larger spectroscopic samples from upcoming ground-based instruments will provide precise constraints on ages and metallicities at $z\gtrsim1$. Combining these with precise JWST $z>2$ quiescent-galaxy stellar-mass functions will provide an independent test of formation redshifts derived from spectral fitting.Comment: 16 pages, 3 figures, accepted for publication in Ap

High-velocity outflows in massive post-starburst galaxies at z &gt; 1

We investigate the prevalence of galactic-scale outflows in post-starburst (PSB) galaxies at high redshift (1 1010M⊙⁠) PSBs at z > 1, there is clear evidence for a strong blue-shifted component to the Mg ii absorption feature, indicative of high-velocity outflows (⁠vout∼1150±160kms−1⁠) in the interstellar medium. We conclude that such outflows are typical in massive PSBs at this epoch, and potentially represent the residual signature of a feedback process that quenched these galaxies. Using full spectral fitting, we also obtain a typical stellar velocity dispersion σ* for these PSBs of ∼200kms−1⁠, which confirms they are intrinsically massive in nature (dynamical mass Md∼1011M⊙⁠). Given that these high-z PSBs are also exceptionally compact (re ∼ 1–2kpc⁠) and spheroidal (Sérsic index n ∼ 3), we propose that the outflowing winds may have been launched during a recent compaction event (e.g. major merger or disc collapse) that triggered either a centralized starburst or active galactic nuclei (AGN) activity. Finally, we find no evidence for AGN signatures in the optical spectra of these PSBs, suggesting they were either quenched by stellar feedback from the starburst itself, or that if AGN feedback is responsible, the AGN episode that triggered quenching does not linger into the post-starburst phase.Publisher PDFPeer reviewe

Characterising the evolving KK-band luminosity function using the UltraVISTA, CANDELS and HUDF surveys

We present the results of a new study of the K-band galaxy luminosity function (KLF) at redshifts z<3.75, based on a nested combination of the UltraVISTA, CANDELS and HUDF surveys. The large dynamic range in luminosity spanned by this new dataset (3-4 dex over the full redshift range) is sufficient to clearly demonstrate for the first time that the faint-end slope of the KLF at z>0.25 is relatively steep (-1.3<alpha<-1.5 for a single Schechter function), in good agreement with recent theoretical and phenomenological models. Moreover, based on our new dataset we find that a double Schechter function provides a significantly improved description of the KLF at z0.25 the evolution of the KLF is remarkably smooth, with little or no evolution evident at faint (M_K>-20.5) or bright magnitudes (M_K<-24.5). Instead, the KLF is seen to evolve rapidly at intermediate magnitudes, with the number density of galaxies at M_K~-23 dropping by a factor of ~5 over the redshift interval 0.25<z<3.75. Motivated by this, we explore a simple description of the evolving KLF based on a double Schechter function with fixed faint-end slopes (alpha_1=-0.5, alpha_2=-1.5) and a shared characteristic magnitude (M_K*). According to this parameterisation, the normalisation of the component which dominates the faint-end of the KLF remains approximately constant, with phi*_2 decreasing by only a factor of ~2 between z~0 and z~3.25. In contrast, the component which dominates the bright end of the KLF at low redshifts evolves dramatically, becoming essentially negligible by z~3. Finally, we note that within this parameterisation, the observed evolution of M_K* between z~0 and z~3.25 is entirely consistent with M_K* corresponding to a constant stellar mass of M*~5x10^10 Msun at all redshifts.Comment: 18 pages, 10 figures, accepted for publication in MNRA

Decolonizing Listening: Towards an Equitable Approach to Speech Training for the Actor.

This article confirms and deepens an understanding of the negative impact of teaching culturally embedded speech standards to actors who are “othered” by a dominant “somatic norm” within the performing arts. The author analyzes evidence from a three-year longitudinal study of actors within a UK conservatory in relation to the critical frame of the somatic norm and colonized listening practices in the performing arts. The author identifies conscious and unconscious bias within traditional training methods and proposes a decolonizing approach to listening within foundational speech training. The ideological shift outlined follows the “affective turn” in the humanities and social sciences and moves away from the culturally embedded listening at the core of “effective” speech methods, which focus solely on clarity and intelligibility. The outcome of this research is a radical performance pedagogy, which values the intersectional identities and linguistic capital of students from pluralistic backgrounds. The revised curriculum offers an approach to affective speaking and listening that assumes an equality of understanding from the outset, and requires actors, actor trainers, and, ultimately, audiences to de-colonize their listening ears

NOTCH signaling specifies arterial-type definitive hemogenic endothelium from human pluripotent stem cells

NOTCH signaling is required for the arterial specification and formation of hematopoietic stem cells (HSCs) and lympho-myeloid progenitors in the embryonic aorta-gonad-mesonephros region and extraembryonic vasculature from a distinct lineage of vascular endothelial cells with hemogenic potential. However, the role of NOTCH signaling in hemogenic endothelium (HE) specification from human pluripotent stem cell (hPSC) has not been studied. Here, using a chemically defined hPSC differentiation system combined with the use of DLL1-Fc and DAPT to manipulate NOTCH, we discover that NOTCH activation in hPSC-derived immature HE progenitors leads to formation of CD144+CD43−CD73−DLL4+Runx1 + 23-GFP+ arterial-type HE, which requires NOTCH signaling to undergo endothelial-to-hematopoietic transition and produce definitive lympho-myeloid and erythroid cells. These findings demonstrate that NOTCH-mediated arterialization of HE is an essential prerequisite for establishing definitive lympho-myeloid program and suggest that exploring molecular pathways that lead to arterial specification may aid in vitro approaches to enhance definitive hematopoiesis from hPSCs