404 research outputs found

    Experiences of learning through collaborative evaluation from a masters programme in professional education

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    This paper presents findings from a collaborative evaluation project within a masters programme in professional education. The project aimed to increase knowledge of research methodologies and methods through authentic learning where participants worked in partnership with the tutor to evaluate the module which they were studying. The project processes, areas of the course evaluated and the data collection methods are outlined. The findings focus on key themes from evaluating the effectiveness of using a collaborative evaluation approach, including: enhanced student engagement; creativity of the collaborative evaluation approach; equality between the tutor and students; and enhanced research skills. Discussion focuses on the outcomes and effectiveness of the project and tutor reflections on adopting a collaborative approach. This paper highlights lessons from the project relevant to those interested in staff-student partnership approaches and those facilitating postgraduate learning and teaching programmes and educational research courses

    Spectral Templates Optimal for Selecting Galaxies at z > 8 with JWST

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    The selection of high-redshift galaxies often involves spectral energy distribution (SED) fitting to photometric data, an expectation for contamination levels, and measurement of sample completeness -- all vetted through comparison to spectroscopic redshift measurements of a sub-sample. The first JWST data is now being taken over several extragalactic fields, to different depths and across various areas, which will be ideal for the discovery and classification of galaxies out to distances previously uncharted. As spectroscopic redshift measurements for sources in this epoch will not be initially available to compare with the first photometric measurements of z > 8 galaxies, robust photometric redshifts are of the utmost importance. Galaxies at z > 8 are expected to have bluer rest-frame ultraviolet (UV) colors than typically-used model SED templates, which could lead to catastrophic photometric redshift failures. We use a combination of BPASS and Cloudy models to create a supporting set of templates that match the predicted rest-UV colors of z > 8 the simulated galaxies in a mock catalog (Yung et al. 2022), which mimics expected field depths and areas of the Cosmic Evolution Early Release Science Survey (CEERS: m5σ_{5\sigma} ~ 28.6 over ~100 arcmin2^2; Finkelstein et al. 2022a, Bagley et al. 2022). We use EAZY to highlight the improvements in redshift recovery with the inclusion of our new template set and suggest criteria for selecting galaxies at 8 < z < 10 with JWST, providing an important test case for observers venturing into this new era of astronomy.Comment: 14 pages, 10 figures, submitted to ApJ. SED templates published at: ceers.github.io/LarsonSEDTemplate

    CLEAR: High-Ionization [Ne V] λ{\lambda}3426 Emission-line Galaxies at 1.4<z<2.31.4 <z< 2.3

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    We analyze a sample of 25 [Ne V] λ\lambda3426 emission-line galaxies at 1.4<z<2.31.4<z<2.3 using Hubble Space Telescope/Wide Field Camera 3 G102 and G141 grism observations from the CANDELS Lyman-α\alpha Emission at Reionization (CLEAR) survey. [Ne V] emission probes extremely energetic photoionization (97.11-126.21 eV), and is often attributed to energetic radiation from active galactic nuclei (AGN), shocks from supernova, or an otherwise very hard ionizing spectrum from the stellar continuum. In this work, we use [Ne V] in conjunction with other rest-frame UV/optical emission lines ([O II] λλ\lambda\lambda3726,3729, [Ne III] λ\lambda3869, HÎČ\beta, [O III] λλ\lambda\lambda4959,5007, Hα\alpha+[N II] λλ\lambda\lambda6548,6583, [S II] λλ\lambda\lambda6716,6731), deep (2--7 Ms) X-ray observations (from Chandra), and mid-infrared imaging (from Spitzer) to study the origin of this emission and to place constraints on the nature of the ionizing engine. The majority of the [Ne V]-detected galaxies have properties consistent with ionization from AGN. However, for our [Ne V]-selected sample, the X-ray luminosities are consistent with local (zâ‰Č0.1z\lesssim 0.1) X-ray-selected Seyferts, but the [Ne V] luminosities are more consistent with those from z∌1z\sim 1 X-ray-selected QSOs. The excess [Ne V] emission requires either reduced hard X-rays, or a ∌\sim0.1 keV excess. We discuss possible origins of the apparent [Ne V] excess, which could be related to the ``soft (X-ray) excess'' observed in some QSOs and Seyferts, and/or be a consequence of a complex/anisotropic geometry for the narrow line region, combined with absorption from a warm, relativistic wind ejected from the accretion disk. We also consider implications for future studies of extreme high-ionization systems in the epoch of reionization (z≳6z \gtrsim 6) with JWST.Comment: 17 pages + 5 (appendix), 7 figures + 2(appendix

    The FENIKS Survey: Spectroscopic Confirmation of Massive Quiescent Galaxies at z ~ 3-5

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    The measured ages of massive, quiescent galaxies at z∌3−4z\sim 3-4 imply that massive galaxies quench as early as z∌6z\sim 6. While the number of spectroscopic confirmations of quiescent galaxies at z<3z < 3 has increased over the years, there are only a handful at z>3.5z > 3.5. We report spectroscopic redshifts of one secure (z=3.757z=3.757) and two tentative (z=3.336z = 3.336, z=4.673z=4.673) massive (log⁥(M∗/M⊙)>10.3\log(M_\ast/M_\odot) > 10.3) quiescent galaxies with 11 hours of Keck/MOSFIRE KK-band observations. Our candidates were selected from the FENIKS survey, which uses deep Gemini/Flamingos-2 KbK_b KrK_r imaging optimized for increased sensitivity to the characteristic red colors of galaxies at z>3z > 3 with strong Balmer/4000 \AA\ breaks. The rest-frame UVJUVJ and (ugi)s(ugi)_s colors of 3/4 quiescent candidates are consistent with 1−21-2 Gyr old stellar populations. This places these galaxies as the oldest objects at these redshifts, and challenges the notion that quiescent galaxies at z>3z > 3 are all recently-quenched, "post-starburst'' galaxies. Our spectroscopy shows that the other quiescent-galaxy candidate is a broad-line AGN (z=3.594z = 3.594) with strong, redshifted HÎČH\beta+[O III] emission with a velocity offset >1000>1000 km/s, indicative of a powerful outflow. The star-formation history of our highest redshift candidate suggests that its progenitor was already in place by z∌7−11z \sim 7-11, reaching ∌\sim 1011M⊙^{11} M_{\odot} by z≃10z \simeq 10. These observations reveal the limit of what is possible with deep near-infrared photometry and targeted spectroscopy from the ground and demonstrate that secure spectroscopic confirmation of quiescent galaxies at z>4z > 4 is only feasible with JWST.Comment: 20 pages, 11 figures, submitted to Ap

    Using [Ne V]/[Ne III] to Understand the Nature of Extreme-Ionization Galaxies

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    Spectroscopic studies of extreme-ionization galaxies (EIGs) are critical to our understanding of exotic systems throughout cosmic time. These EIGs exhibit spectral features requiring >54.42 eV photons: the energy needed to fully ionize helium into He2+ and emit He II recombination lines. They are likely key contributors to reionization, and they can also probe exotic stellar populations or accretion onto massive black holes. To facilitate the use of EIGs as probes of high ionization, we focus on ratios constructed from strong rest-frame UV/optical emission lines, specifically [O III] 5008, H-beta, [Ne III] 3870, [O II] 3727,3729, and [Ne V] 3427. These lines probe the relative intensity at energies of 35.12, 13.62, 40.96, 13.62 eV, and 97.12, respectively, covering a wider range of ionization than traced by other common rest-frame UV/optical techniques. We use ratios of these lines ([Ne V]/[Ne III] = Ne53 and [Ne III]/[O II]), which are closely separated in wavelength, and mitigates effects of dust attenuation and uncertainties in flux calibration. We make predictions from photoionization models constructed from Cloudy that use a broad range of stellar populations and black hole accretion models to explore the sensitivity of these line ratios to changes in the ionizing spectrum. We compare our models to observations from the Hubble Space Telescope and James Webb Space Telescope of galaxies with strong high-ionization emission lines at z ~ 0, z ~ 2, and z ~ 7. We show that the Ne53 ratio can separate galaxies with ionization from 'normal' stellar populations from those with AGN and even 'exotic' Population III models. We introduce new selection methods to identify galaxies with photoionization driven by Population III stars or intermediate-mass black hole accretion disks that could be identified in upcoming high-redshift spectroscopic surveys.Comment: 16 pages, 5 figures, 1 table. Accepted in Ap

    Brain Biomarkers and Pre-Injury Cognition are Associated with Long-Term Cognitive Outcome in Children with Traumatic Brain Injury

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    BACKGROUND: Children with traumatic brain injury (TBI) are frequently at risk of long-term impairments of attention and executive functioning but these problems are difficult to predict. Although deficits have been reported to vary with injury severity, age at injury and sex, prognostication of outcome remains imperfect at a patient-specific level. The objective of this proof of principle study was to evaluate a variety of patient variables, along with six brain-specific and inflammatory serum protein biomarkers, as predictors of long-term cognitive outcome following paediatric TBI. METHOD: Outcome was assessed in 23 patients via parent-rated questionnaires related to attention deficit hyperactivity disorder (ADHD) and executive functioning, using the Conners 3rd Edition Rating Scales (Conners-3) and Behaviour Rating Inventory of Executive Function (BRIEF) at a mean time since injury of 3.1 years. Partial least squares (PLS) analyses were performed to identify factors measured at the time of injury that were most closely associated with outcome on (1) the Conners-3 and (2) the Behavioural Regulation Index (BRI) and (3) Metacognition Index (MI) of the BRIEF. RESULTS: Higher levels of neuron specific enolase (NSE) and lower levels of soluble neuron cell adhesion molecule (sNCAM) were associated with higher scores on the inattention, hyperactivity/impulsivity and executive functioning scales of the Conners-3, as well as working memory and initiate scales of the MI from the BRIEF. Higher levels of NSE only were associated with higher scores on the inhibit scale of the BRI. CONCLUSIONS: NSE and sNCAM show promise as reliable, early predictors of long-term attention-related and executive functioning problems following paediatric TBI

    JWST's TEMPLATES for Star Formation: The First Resolved Gas-Phase Metallicity Maps of Dust-Obscured Star-Forming Galaxies at zz ∌\sim 4

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    We present the first spatially resolved maps of gas-phase metallicity for dust-obscured star-forming galaxies (DSFGs) at zz ∌\sim 4, from the JWST TEMPLATES Early Release Science program, derived from NIRSpec integral field unit spectroscopy of the Hα\alpha and [NII] emission lines. Empirically derived literature optical line calibrations are used to determine that the sources are highly metal rich, with both appearing to display regions of supersolar metallicity, particularly in SPT2147-50. While we cannot rule out shocks or AGN in these regions, we suggest that the two systems have already undergone significant enrichment as a result of their extremely high star-formation rates. Utilising ALMA rest-frame 380ÎŒ\mum continuum and [CI](3^3P2_2-3^3P1_1) line maps we compare metallicity and gas-to-dust ratio variations in the two galaxies, finding the two to be anticorrelated on highly resolved spatial scales, consistent with various literature studies of zz ∌\sim 0 galaxies. The data are indicative of the enormous potential of JWST to probe the enrichment of the interstellar medium on ∌\simkpc scales in extremely dust-obscured systems at zz ∌\sim 4 and beyond.Comment: 12 pages, 5 figures, submitted to Ap
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