86 research outputs found

    The Ontology of Scholar-Administrators: Empirical Inferences from Five Senior Administrators Who Published

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    The purpose of this study was to fill a gap in existing literature on scholar-administrators and understand the lived experience of scholar-administrators who published. Using an interpretative phenomenological approach to extract themes from detailed case studies of five senior academic administrators who have published, the researchers’ empirical inferences from the five detailed case histories reveal the challenges and rewards of producing scholarship as a scholar-administrator. Their findings show that the administrators were more connected to the people within and outside the university, their own field of practice, and with the university. The impact of scholarship on scholar-administrators goes beyond publications. Continuation of being a scholar-practitioner has significant impact on networking scope of administrators keeping the educational entities they lead abreast of environmental trends to adapt to. Future research should replicate our study to increase the generalizability of its findings

    Advancing the Next Generation of Higher Education Scholars: An Examination of One Doctoral Classroom

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    Course content in graduate school is especially important in terms of helping students make progress toward a doctorate. However, content is merely one aspect of developing successful students. This article highlights the value of creating an affirming learning environment by discussing one graduate class on Qualitative Policy Research. The majority of student participants were graduate students of color. The authors discuss the pedagogical approaches guiding this course and outline ways in which the instructor served to create safe spaces that invited as well as validated diverse perspectives and made the research process transparent. These efforts resulted in the production of high quality research used as pilot studies for successful dissertation defenses, accepted presentations at scholarly conferences, and published articles in peer-reviewed journals. Throughout this article, suggestions for replicating a similar course environment are discussed

    CLASH-X: A Comparison of Lensing and X-ray Techniques for Measuring the Mass Profiles of Galaxy Clusters

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    We present profiles of temperature (Tx), gas mass, and hydrostatic mass estimated from new and archival X-ray observations of CLASH clusters. We compare measurements derived from XMM and Chandra observations with one another and compare both to gravitational lensing mass profiles derived with CLASH HST and ground-based lensing data. Radial profiles of Chandra and XMM electron density and enclosed gas mass are nearly identical, indicating that differences in hydrostatic masses inferred from X-ray observations arise from differences in Tx measurements. Encouragingly, cluster Txs are consistent with one another at ~100-200 kpc radii but XMM Tx systematically decline relative to Chandra Tx at larger radii. The angular dependence of the discrepancy suggests additional investigation on systematics such as the XMM point spread function correction, vignetting and off-axis responses. We present the CLASH-X mass-profile comparisons in the form of cosmology-independent and redshift-independent circular-velocity profiles. Ratios of Chandra HSE mass profiles to CLASH lensing profiles show no obvious radial dependence in the 0.3-0.8 Mpc range. However, the mean mass biases inferred from the WL and SaWLens data are different. e.g., the weighted-mean value at 0.5 Mpc is = 0.12 for the WL comparison and = -0.11 for the SaWLens comparison. The ratios of XMM HSE mass profiles to CLASH lensing profiles show a pronounced radial dependence in the 0.3-1.0 Mpc range, with a weighted mean mass bias of value rising to ~0.3 at ~1 Mpc for the WL comparison and of 0.25 for SaWLens comparison. The enclosed gas mass profiles from both Chandra and XMM rise to a value 1/8 times the total-mass profiles inferred from lensing at 0.5 Mpc and remain constant outside of that radius, suggesting that [8xMgas] profiles may be an excellent proxy for total-mass profiles at >0.5 Mpc in massive galaxy clusters.Comment: Accepted to ApJ; 24 pages; scheduled to appear in the Oct 10, 2014 issue. This version corrects the typographical error in the superscripts for Equation (2) to include the square of (r/r_core). The correct version of this equation was used in the analysi

    Reality Hackers: The Next Wave of Media Revolutionaries

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    Just as the printing press gave rise to the nation-state, emerging technologies are reshaping collective identities and challenging our understanding of what it means to be human. Should citizens have the right to be truly anonymous on-line? Should we be concerned about the fact that so many people are choosing to migrate to virtual worlds? Are injectible microscopic radio-frequency ID chips a blessing or a curse? Is the use of cognitive enhancing nootropics a human right or an unforgivable transgression? Should genomic data about human beings be hidden away with commercial patents or open-sourced like software? Should hobbyists known as biohackers be allowed to experiment with genetic engineering in their home laboratories? The time-frame for acting on such questions is relatively short, and these decisions are too important to be left up to a small handful of scientists and policymakers. If democracy is to continue as a viable alternative to technocracy, the average citizen must become more involved in these debates. To borrow a line from the computer visionary Ted Nelson, all of us can -- and must -- understand technology now. Challenging the popular stereotype of hackers as ciminal sociopaths, reality hackers uphold the basic tenets of what Steven Levy (1984) terms the hacker ethic. These core principles include a commitment to: sharing, openness, decentralization, public access to information, and the use of new technologies to make the world a better place.https://digitalcommons.trinity.edu/mono/1000/thumbnail.jp

    PEARLS: Low Stellar Density Galaxies in the El Gordo Cluster Observed with JWST

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    A full understanding of how unusually large "Ultra Diffuse Galaxies" (UDGs) fit into our conventional understanding of dwarf galaxies remains elusive, despite the large number of objects identified locally. A natural extension of UDG research is the study of similar galaxies at higher redshift to establish how their properties may evolve over time. However, this has been a challenging task given how severely systematic effects and cosmological surface brightness dimming inhibit our ability to study low-surface brightness galaxies at high-zz. Here, we present an identification of low stellar surface density galaxies (LDGs), likely the progenitors of local UDGs, at moderate redshift with deep near-IR observations of the El Gordo cluster at z=0.87z = 0.87 with JWST. By stacking 8 NIRCAM filters, we are able to achieve an apparent surface brightness sensitivity of 24.5924.59 mag arcsec−2^{-2}, faint enough to be complete to the bright end of the LDG population. Our analysis identifies significant differences between this population and local UDGs, such as their color and size distributions, which suggest that UDG progenitors are bluer and more extended at high-zz than at z=0z = 0. This suggests that multiple mechanisms are responsible for UDG formation and that prolonged transformation of cluster dwarfs is not a primary UDG formation mechanism at high-zz. Furthermore, we find a slight overabundance of LDGs in El Gordo, and, in contrast to findings in local clusters, our analysis does not show a deficit of LDGs in the center of El Gordo, implying that tidal destruction of LDGs is significant between z=0.87z = 0.87 and z=0z = 0.Comment: Resubmitted to ApJ after minor revision

    JWST NIRCam Photometry: A Study of Globular Clusters Surrounding Bright Elliptical Galaxy VV 191a at z=0.0513

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    James Webb Space Telescope NIRCam images have revealed 443 globular cluster (GC) candidates around the z=0.0513z=0.0513 elliptical galaxy VV 191a. NIRCam broadband observations are made at 0.9-4.5 μ\mum using filters F090W, F150W, F356W, and F444W. Using photometry, the data is analyzed to present color-magnitude diagrams (CMDs) that suggest a fairly uniform population of GCs. Color histograms show a unimodal color distribution that is well fit by a single Gaussian, using color to primarily trace the metallicity. The findings show the sample's globular cluster luminosity function (GCLF) does not reach the turnover value and is, therefore, more luminous than what is typically expected, with an absolute AB magnitude, MF090W=−8.70M_{F090W} = -8.70 mag, reaching within nearly one magnitude of the classical turnover value. We attribute this to the completeness in the sample. Models show that the mass estimate of the GCs detected tends to be more massive, reaching upward of ≃107M⊙\simeq 10^7 M_{\odot}. However, the results show that current GC models do not quite align with the data. We find that the models appear to be bluer than the JWST data in the reddest (F356W-F444W) filters and redder than the data in the bluest (F090W-F150W) filters and may need to be revised to improve the modeling of near-IR colors of old, metal-poor stellar populations.Comment: 11 pages, 7 figure

    EPOCHS VII: Discovery of high redshift (6.5<z<126.5 < z < 12) AGN candidates in JWST ERO and PEARLS data

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    We present an analysis of a sample of robust high redshift galaxies selected photometrically from the `blank' fields of the Prime Extragalactic Areas for Reionization Science (PEARLS) survey and Early Release Observations (ERO) data of the James Webb Space Telescope (JWST) with the aim of selecting candidate high redshift active galactic nuclei (AGN). Sources were identified from the parent sample using a threefold selection procedure, which includes spectral energy distribution (SED) fitting to identify sources that are best fitted by AGN SED templates, a further selection based on the relative performance of AGN and non-AGN models, and finally morphological fitting to identify compact sources of emission, resulting in a purity-oriented procedure. Using this procedure, we identify a sample of nine AGN candidates at 6.5<z<126.5 < z < 12, from which we constrain their physical properties as well as measure a lower bound on the AGN fraction in this redshift range of 5±15 \pm 1\%. As this is an extreme lower limit due to our focus on purity and our SEDs being calibrated for unobscured Type 1 AGN, this demonstrates that AGN are perhaps quite common at this early epoch. The rest-frame UV colors of our candidate objects suggest that these systems are potentially candidate obese black hole galaxies (OBG), or AGN with very little galaxy component. We also investigate emission from our sample sources from fields overlapping with Chandra and VLA surveys, allowing us to place X-ray and 3 GHz radio detection limits on our candidates. Of note is a z=11.9z = 11.9 candidate source exhibiting an abrupt morphological shift in the reddest band as compared to the bluer bands, indicating a potential merger or an unusually strong outflow.Comment: Submitted to MNRAS, 12 pages, 11 figures, typos correcte

    Magellanic System Stars Identified in the SMACS J0723.3-7327 JWST ERO Images

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    We identify 68 distant stars in JWST/NIRCam ERO images of the field of galaxy cluster SMACS J0723.3-7327 (SMACS 0723). Given the relatively small (∼\sim10∘10^{\circ}) angular separation between SMACS 0723 and the Large Magellanic Cloud, it is likely that these stars are associated with the LMC outskirts or Leading Arm. This is further bolstered by a spectral energy distribution analysis, which suggests an excess of stars at a physical distance of 40−10040-100 kpc, consistent with being associated with or located behind the Magellanic system. In particular, we find that the overall surface density of stars brighter than 27.0 mag in the field of SMACS 0723 is ∼\sim2.3 times that of stars in a blank field with similar galactic latitude (the North Ecliptic Pole Time Domain Field), and that the density of stars in the SMACS 0723 field with SED-derived distances consistent with the Magellanic system is ∼\sim7.3 times larger than that of the blank field. The candidate stars at these distances are consistent with a stellar population at the same distance modulus with [Fe/H] =−1.0= -1.0 and an age of ∼\sim5.05.0 Gyr. On the assumption that all of the 68 stars are associated with the LMC, then the stellar density of the LMC at the location of the SMACS 0723 field is ∼\sim710710 stars kpc−3^{-3}, which helps trace the density of stars in the LMC outskirts.Comment: Submitted to ApJ, comments welcom

    PEARLS: A Potentially Isolated Quiescent Dwarf Galaxy with a TRGB Distance of 31 Mpc

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    A wealth of observations have long suggested that the vast majority of isolated classical dwarf galaxies (M∗=107M_*=10^7-10910^9 M⊙_\odot) are currently star-forming. However, recent observations of the large abundance of "Ultra-Diffuse Galaxies" beyond the reach of previous large spectroscopic surveys suggest that our understanding of the dwarf galaxy population may be incomplete. Here we report the serendipitous discovery of an isolated quiescent dwarf galaxy in the nearby Universe, which was imaged as part of the PEARLS GTO program. Remarkably, individual red-giant branch stars are visible in this near-IR imaging, suggesting a distance of 3131 Mpc, and a wealth of archival photometry point to an sSFR of 2×10−122\times10^{-12} yr−1^{-1}. Spectra obtained with the Lowell Discovery Telescope find a recessional velocity consistent with the Hubble Flow and >1500{>}1500 km/s separated from the nearest massive galaxy in SDSS, suggesting that this galaxy was either quenched from internal mechanisms or had a very high-velocity interaction with a nearby massive galaxy in the past. This analysis highlights the possibility that many nearby quiescent dwarf galaxies are waiting to be discovered and that JWST has the potential to identify them.Comment: Submitted to ApJ Letters. Comments welcome

    Are JWST/NIRCam color gradients in the lensed z=2.3 dusty star-forming galaxy El Anzuelo due to central dust attenuation or inside-out galaxy growth?

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    Gradients in the mass-to-light ratio of distant galaxies impede our ability to characterize their size and compactness. The long-wavelength filters of JWSTJWST's NIRCam offer a significant step forward. For galaxies at Cosmic Noon (z∼2z\sim2), this regime corresponds to the rest-frame near-infrared, which is less biased towards young stars and captures emission from the bulk of a galaxy's stellar population. We present an initial analysis of an extraordinary lensed dusty star-forming galaxy (DSFG) at z=2.3z=2.3 behind the El GordoEl~Gordo cluster (z=0.87z=0.87), named El AnzueloEl~Anzuelo ("The Fishhook") after its partial Einstein-ring morphology. The FUV-NIR SED suggests an intrinsic star formation rate of 81−2+7 M⊙ yr−181^{+7}_{-2}~M_\odot~{\rm yr}^{-1} and dust attenuation AV≈1.6A_V\approx 1.6, in line with other DSFGs on the star-forming main sequence. We develop a parametric lens model to reconstruct the source-plane structure of dust imaged by the Atacama Large Millimeter/submillimeter Array, far-UV to optical light from HubbleHubble, and near-IR imaging with 8 filters of JWSTJWST/NIRCam, as part of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) program. The source-plane half-light radius is remarkably consistent from ∼1−4.5 μ\sim 1-4.5~\mum, despite a clear color gradient where the inferred galaxy center is redder than the outskirts. We interpret this to be the result of both a radially-decreasing gradient in attenuation and substantial spatial offsets between UV- and IR-emitting components. A spatial decomposition of the SED reveals modestly suppressed star formation in the inner kiloparsec, which suggests that we are witnessing the early stages of inside-out quenching.Comment: 29 pages, 11 figures, 5 tables. Accepted for publication in Ap
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