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Articles 1 - 30 of 36
Full-Text Articles in Physical Sciences and Mathematics
Trends In The Ams Education Symposium And Highlights From 2012, Rajul Pandya, Donna Charlevoix, Eugene Cordero, David Smith, Sepi Yalda
Trends In The Ams Education Symposium And Highlights From 2012, Rajul Pandya, Donna Charlevoix, Eugene Cordero, David Smith, Sepi Yalda
Faculty Publications, Meteorology and Climate Science
The Department of Meteorology (now Atmospheric Sciences) at the University of Utah faced reductions in state funding in 2008 that reduced support for nontenured instructors at the same time that the faculty were becoming increasingly successful obtaining federally supported research grants. A faculty retreat and subsequent discussions led to substantive curriculum changes to modernize the curriculum, enhance course offerings for undergraduate and graduate students, and improve the overall efficiency of the academic program. Maintaining discipline standards and existing teaching loads were important constraints on these changes. Key features of the curriculum revisions for undergraduate majors included eliminating a very rigid …
Using Marine Snails To Teach Biogeography And Macroevolution: The Role Of Larvae And Dispersal Ability In The Evolution And Persistence Of Species, Jonathan R. Hendricks
Using Marine Snails To Teach Biogeography And Macroevolution: The Role Of Larvae And Dispersal Ability In The Evolution And Persistence Of Species, Jonathan R. Hendricks
Faculty Publications
While some marine animals are capable of traveling great distances, many have limited mobility as adults and spend the majority of their lifetimes in a small geographical area or may even be cemented to a single place. While it might be expected that species with limited mobility would have small geographic distributions, some nevertheless occur over very large areas. This is the case for some marine snails (gastropods). A key factor that impacts the geographic distribution of marine snails is the type of larvae they have during the phase of their life history that follows hatching from an egg. Because …
Water Vapor And Temperature Comparisons Between Airs/Amsu-A And In Situ Aircraft Observations From 87°N To 67°S And Sensitivities To Spatial And Temporal Differences, Minghui Diao, Loayeh Jumbam, Justin Sheffield, Eric Wood, Mark Zondlo
Water Vapor And Temperature Comparisons Between Airs/Amsu-A And In Situ Aircraft Observations From 87°N To 67°S And Sensitivities To Spatial And Temporal Differences, Minghui Diao, Loayeh Jumbam, Justin Sheffield, Eric Wood, Mark Zondlo
Faculty Publications, Meteorology and Climate Science
No abstract available.
Fast Melt Cooled Superconducting Alloys: (Bi1.97pb0.03sr2can‐1cuno2n+4+Δ)2 N/N’ N<24 Intergrowth, J. Kmiec, Juana Acrivos, D. Gulamova, J. Chigvinadze
Fast Melt Cooled Superconducting Alloys: (Bi1.97pb0.03sr2can‐1cuno2n+4+Δ)2 N/N’ N<24 Intergrowth, J. Kmiec, Juana Acrivos, D. Gulamova, J. Chigvinadze
Faculty Publications, Chemistry
High temperature layer superconducting cuprate (HTLSC) alloys: (Bi1.97Pb0.03Sr2Can-1CunO2n+4+δ)2 called (2s:2:n-1:n) have been grown from n-oxide stoichiometric melts in concentrated sun flux, followed by rapid cooling SFQA technology that preserves the melt tiling after annealing at 845±5oC**. Synchrotron XRD at the DOE SLAC-SSRL near the Cu K-edge has identified the mixing of n ≠ n’ alloys as observed by many in thin films last century. An ideal D17 4h Space Group structure obtains {an, bn, cn} = {3.815 Å, an+ubn, 2dP(n+3)+ucn} where dP is a perovskite sandwich, (CuO2)1/2|_Ca|(CuO2)1/2, thickness, and un are the amplitudes of periodic lattice distortions, PLD also observed …
Bioactive Trace Metal Distributions And Biogeochemical Controls In The Southern Ocean, Christopher Measures, Mariko Hatta, Maxime Grand
Bioactive Trace Metal Distributions And Biogeochemical Controls In The Southern Ocean, Christopher Measures, Mariko Hatta, Maxime Grand
Faculty Publications
Extensive sampling in many regions of the Southern Ocean has demonstrated that surface water concentrations of dissolved Fe are low enough to limit phytoplankton growth. In contrast, there is currently no evidence that other bioactive elements (e.g., Mn, Zn, Co) are similarly limiting. Although atmospheric input of dissolved Fe to Southern Ocean surface waters appears to be low, resuspension of sediments from shallow regions around islands and the Antarctic coastline can inject significant amounts of Fe into the surrounding waters, stimulating primary production and providing a natural laboratory for studying the response of biological systems to natural Fe fertilization processes. …
Effect Of Particle Statistics In Strongly Correlated Two-Dimensional Hubbard Models, Ehsan Khatami, Marcos Rigol
Effect Of Particle Statistics In Strongly Correlated Two-Dimensional Hubbard Models, Ehsan Khatami, Marcos Rigol
Faculty Publications
We study the onset of particle statistics effects as the temperature is lowered in strongly correlated two-dimensional Hubbard models. We utilize numerical linked-cluster expansions and focus on the properties of interacting lattice fermions and two-component hard-core bosons. In the weak-coupling regime, where the ground state of the bosonic system is a superfluid, the thermodynamic properties of the two systems at half filling exhibit very large differences even at high temperatures. In the strong-coupling regime, where the low-temperature behavior is governed by a Mott insulator for either particle statistics, the agreement between the thermodynamic properties of both systems extends to regions …
Student-Teacher Interactions For Bringing Out Student Ideas About Energy, Benedikt W. Harrer, Michael Wittmann, Rachel Scherr
Student-Teacher Interactions For Bringing Out Student Ideas About Energy, Benedikt W. Harrer, Michael Wittmann, Rachel Scherr
Faculty Publications
Modern middle school science curricula use group activities to help students express their thinking and enable them to work together like scientists. We are studying rural 8th grade science classrooms using materials on energy. Even after spending several months with the same curriculum on other physics topics, students' engagement in group activities seems to be restricted to creating lists of words that are associated with energy. Though research suggests that children have rich and potentially valuable ideas about energy, our students don't seem to spontaneously use and express their ideas in the classroom. Only within or after certain interactions with …
Reproduction Of Twentieth Century Intradecadal To Multidecadal Surface Temperature Variability In Radiatively Forced Coupled Climate Models, Patrick T. Brown, Eugene C. Cordero, Steven A. Mauget
Reproduction Of Twentieth Century Intradecadal To Multidecadal Surface Temperature Variability In Radiatively Forced Coupled Climate Models, Patrick T. Brown, Eugene C. Cordero, Steven A. Mauget
Faculty Publications, Meteorology and Climate Science
[1] Coupled Model Intercomparison Project 3 simulations that included time-varying radiative forcings were ranked according to their ability to consistently reproduce twentieth century intradecadal to multidecadal (IMD) surface temperature variability at the 5° by 5° spatial scale. IMD variability was identified using the running Mann-Whitney Z method. Model rankings were given context by comparing the IMD variability in preindustrial control runs to observations and by contrasting the IMD variability among the ensemble members within each model. These experiments confirmed that the inclusion of time-varying external forcings brought simulations into closer agreement with observations. Additionally, they illustrated that the magnitude of …
Will Extreme Climatic Events Facilitate Biological Invasions?, Jeffrey M. Diez, Carla M. D'Antonio, Jeffrey S. Dukes, Edwin D. Grosholz, Julian D. Olden, Cascade J.B. Sorte, Dana M. Blumenthal, Bethany A. Bradley, Regan I. Early, Inés Ibáñez, Sierra J. Jones, Joshua J. Lawler, Luke P. Miller
Will Extreme Climatic Events Facilitate Biological Invasions?, Jeffrey M. Diez, Carla M. D'Antonio, Jeffrey S. Dukes, Edwin D. Grosholz, Julian D. Olden, Cascade J.B. Sorte, Dana M. Blumenthal, Bethany A. Bradley, Regan I. Early, Inés Ibáñez, Sierra J. Jones, Joshua J. Lawler, Luke P. Miller
Faculty Publications, Biological Sciences
Extreme climatic events (ECEs) – such as unusual heat waves, hurricanes, floods, and droughts – can dramatically affect ecological and evolutionary processes, and these events are projected to become more frequent and more intense with ongoing climate change. However, the implications of ECEs for biological invasions remain poorly understood. Using concepts and empirical evidence from invasion ecology, we identify mechanisms by which ECEs may influence the invasion process, from initial introduction through establishment and spread. We summarize how ECEs can enhance invasions by promoting the transport of propagules into new regions, by decreasing the resistance of native communities to establishment, …
Quantum Quenches In Disordered Systems: Approach To Thermal Equilibrium Without A Typical Relaxation Time, Ehsan Khatami, Marcos Rigol, Armando Relaño, Antonio García-García
Quantum Quenches In Disordered Systems: Approach To Thermal Equilibrium Without A Typical Relaxation Time, Ehsan Khatami, Marcos Rigol, Armando Relaño, Antonio García-García
Faculty Publications
We study spectral properties and the dynamics after a quench of one-dimensional spinless fermions with short-range interactions and long-range random hopping. We show that a sufficiently fast decay of the hopping term promotes localization effects at finite temperature, which prevents thermalization even if the classical motion is chaotic. For slower decays, we find that thermalization does occur. However, within this model, the latter regime falls in an unexpected universality class, namely, observables exhibit a power-law (as opposed to an exponential) approach to their thermal expectation values.
Résonance Dans Alliages Des Couches Supraconductrices Refroidi Rapidement: (Bi1.7pb0.3sr2can‐1cuno2n+4+Δ)2, N=1 To 9détecté Par Local Renforcée Atomique Xrd, Juana Acrivos, J. Chigvinadze, D. Gulamova
Résonance Dans Alliages Des Couches Supraconductrices Refroidi Rapidement: (Bi1.7pb0.3sr2can‐1cuno2n+4+Δ)2, N=1 To 9détecté Par Local Renforcée Atomique Xrd, Juana Acrivos, J. Chigvinadze, D. Gulamova
Faculty Publications, Chemistry
Lien résonance dans alliages supraconductrice à haute température (HTLSC): (Bi1.7Pb0.3Sr2Can-1CunO2n+4+δ)2,n=1-9 appelé (2s:2:n-1:n) préparé en Ouzbékistan à partir de oxide fondu par flux concentré du Soleil, suivi d'un refroidissement rapide, technologie SFQA préserve fondre carrelage. Tc,n est mesurée en Tbilissi, et atomique local renforcée synchrotron diffraction des rayons X, (XRD) à proximité de la Cu-K bord est effectuée à DOE National Laboratoire SLAC-SSRL. La structure indexé dans le groupe D17 4h démontre qui (n-1) unîtes: (CuO2)1/2/Ca/(CuO2)1/2 sont intercalés à chaque extrémité de la phase n=1: [(CuO2)1/2/SrO/Bi1.7Pb0.3O/Bi1.7Pb0.3O/SrO/(CuO2)1/2]2. Les effets de surface conduit à intercalations des different n-phase, et à des distorsions réseau …
Covalent Bonds In Superconducting Rapid Cooled Alloys: (Bi1.7pb0.3sr2can‐1cuno2n+4+Δ)2, N=1 To 9 Detected By Local Atomic Enhanced Xrd, J. Kmiec, K. Tyson, Juana Acrivos, D. Gulamova, J. Chigvinadze
Covalent Bonds In Superconducting Rapid Cooled Alloys: (Bi1.7pb0.3sr2can‐1cuno2n+4+Δ)2, N=1 To 9 Detected By Local Atomic Enhanced Xrd, J. Kmiec, K. Tyson, Juana Acrivos, D. Gulamova, J. Chigvinadze
Faculty Publications, Chemistry
High temperature layer superconducting cuprates (HTLSC) alloys: (Bi1.7Pb0.3Sr2Can-1CunO2n+4+δ)2,n=1-9 called (2s:2:n-1:n) prepared in Uzbekistan from melts in concentrated sun flux, followed by rapid cooling, SFQA technology that preserves melt tiling by confinement of conduction layer: |(CuO2)1/2|Ca|(CuO2)1/2]n-1| in the hard shell ||, of the n=1 phase,[(CuO2)1/2|SrO|Bi1.7Pb0.3O|Bi1.7Pb0.3O|SrO|(CuO2)1/2]2. Disproportion leads to different n-phase mixing, and periodic lattice distortions (PLD) through bond resonance covalent crystalaxes: 2(rCu+2+rO-2)=4.2Å>a=3.82Å>d(CuO)+2-3/2d(O3))=3.2Å≈(cn-c1)/2(n-1). Individual phase local bonds Cu-Ca, Cu-Sr, Cu-O-Cu are ascertained by X-Ray diffraction near Cu K-edgefollowed by Cu-Ca bond scattering. The HTLSC density, ρ decrease as n increases obtains Tc,n ~180 K, identified due to n=8 phase on …
Ice Supersaturation And Cirrus Clouds In Hippo Global Campaign #1-5, Minghui Diao, Mark Zondlo
Ice Supersaturation And Cirrus Clouds In Hippo Global Campaign #1-5, Minghui Diao, Mark Zondlo
Faculty Publications, Meteorology and Climate Science
No abstract available.
The 1, 2-Conjecture For Graphs With Relatively Small Chromatic Number, Sogol Jahanbekam, Douglas West
The 1, 2-Conjecture For Graphs With Relatively Small Chromatic Number, Sogol Jahanbekam, Douglas West
Faculty Publications
No abstract provided.
Application Of A Mini-Unmanned Aircraft System For In Situ Monitoring Of Fire Plume Thermodynamics Properties, Caroline Keifer, Craig Clements, Brian Potter
Application Of A Mini-Unmanned Aircraft System For In Situ Monitoring Of Fire Plume Thermodynamics Properties, Caroline Keifer, Craig Clements, Brian Potter
Faculty Publications, Meteorology and Climate Science
Direct measurements of wildland fire plume properties are rare because of difficult access to regions near the fire front and plume. Moisture released from combustion, in addition to added heat, can enhance buoyancy and convection, influencing fire behavior. In this study, a mini unmanned aircraft system (miniUAS) was used to obtain in situ measurements of temperature and relative humidity during a prescribed fire. The miniUAS was successfully maneuvered through the plume and its associated turbulence and provided observations of temperature and humidity profiles from near the centerline of the plume. Within the plume, the water vapor mixing ratio increased by …
Evaluating Modeled Intra- To Multidecadal Climate Variability Using Running Mann–Whitney Z Statistics, Steven A. Mauget, Eugene C. Cordero, Patrick T. Brown
Evaluating Modeled Intra- To Multidecadal Climate Variability Using Running Mann–Whitney Z Statistics, Steven A. Mauget, Eugene C. Cordero, Patrick T. Brown
Faculty Publications, Meteorology and Climate Science
An analysis method previously used to detect observed intra- to multidecadal (IMD) climate regimes was adapted to compare observed and modeled IMD climate variations. Pending the availability of the more appropriate phase 5 Coupled Model Intercomparison Project (CMIP-5) simulations, the method is demonstrated using CMIP-3 model simulations. Although the CMIP-3 experimental design will almost certainly prevent these model runs from reproducing features of historical IMD climate variability, these simulations allow for the demonstration of the method and illustrate how the models and observations disagree. This method samples a time series’s data rankings over moving time windows, converts those ranking sets …
Bond Resonance In Superconducting Rapid Cooled Alloys: (Bi1.7pb0.3sr2can‐1cuno2n+4+Δ)2, N=1 To 9 Detected By Novel Local Atomic Enhanced Xrd, K Tyson, J Kmiec, Juana Acrivos, D. Gulamova, J Chigvinadze
Bond Resonance In Superconducting Rapid Cooled Alloys: (Bi1.7pb0.3sr2can‐1cuno2n+4+Δ)2, N=1 To 9 Detected By Novel Local Atomic Enhanced Xrd, K Tyson, J Kmiec, Juana Acrivos, D. Gulamova, J Chigvinadze
Faculty Publications, Chemistry
We discuss bond resonance in high temperature layer superconducting cuprates, HTLSC alloys: (Bi1.7Pb0.3Sr2Can‐1CunO2n+4+δ)2,n=1‐9 called (2s:2:n‐1:n) prepared in Uzbekistan from melts in concentrated sun flux, followed by rapid cooling, SFQA technology that preserves melt tiling, Tc,n measured in Tiblisi, and local atomic enhanced synchrotron X‐ray diffraction, XRD near the Cu K‐edge at DOE National Laboratory SLAC‐SSRL. The SFQA alloys structure indexed in the ideal D17 4h Space Group indicates (n‐1) units: (CuO2)1/2/Ca/(CuO2)1/2 are intercalated at each end of the n=1 phase [(CuO2)1/2/SrO/Bi1.7Pb0.3O/Bi1.7Pb0.3O/SrO/(CuO2)1/2]2. Surface effects lead to different n‐phase mixing, and periodic lattice distortions, PLD, through bond resonance in crystal axes: 2(rCu+2+rO‐2)=4.2Å …
Particle Transport Over Rough Hillslope Surfaces By Dry Ravel: Experiments And Simulations With Implications For Nonlocal Sediment Flux, Emmanuel Gabet, Morgan Mendoza
Particle Transport Over Rough Hillslope Surfaces By Dry Ravel: Experiments And Simulations With Implications For Nonlocal Sediment Flux, Emmanuel Gabet, Morgan Mendoza
Faculty Publications
Past studies of hillslope evolution have typically assumed that soil creep processes are governed by a linear relationship between local hillslope angle and transport distance. The assumption of “linear diffusion” has fallen out of favor because, when coupled with an expression of mass continuity, it yields unrealistic hillslope profiles. As a consequence, a better understanding of the mechanics of sediment transport is needed. Here we report results from a series of flume experiments performed to investigate sediment transport by dry ravel, a common soil creep process in arid and semiarid environments. We find that, at gentle slopes, transport distances follow …
Numerical Study Of The Thermodynamics Of Clinoatacamite, Ehsan Khatami, Joel Helton, Marcos Rigol
Numerical Study Of The Thermodynamics Of Clinoatacamite, Ehsan Khatami, Joel Helton, Marcos Rigol
Faculty Publications
We study the thermodynamic properties of the clinoatacamite compound, Cu2(OH)3Cl, by considering several approximate models. They include the Heisenberg model on (i) the uniform pyrochlore lattice, (ii) a very anisotropic pyrochlore lattice, and (iii) a kagome lattice weakly coupled to spins that sit on a triangular lattice. We utilize the exact diagonalization of small clusters with periodic boundary conditions and implement a numerical linked-cluster expansion approach for quantum lattice models with reduced symmetries, which allows us to solve model (iii) in the thermodynamic limit. We find a very good agreement between the experimental uniform susceptibility and the numerical results for …
A College-Level Foundational Mathematics Course: Evaluation, Challenges, And Future Directions, Wes Maciejewski
A College-Level Foundational Mathematics Course: Evaluation, Challenges, And Future Directions, Wes Maciejewski
Faculty Research, Scholarly, and Creative Activity
Recently in Ontario, Canada, the College Math Project brought to light startling data on the achievement of students in Ontario's College of Applied Arts and Technology System related to their performance in first-year mathematics courses: one-third of the students had failed their first-year mathematics course or were at risk of not completing their program because of their performance in such a course. Here I present the results of an attempt to address the findings of the College Math Project. A foundational mathematics course, based on the JUMP Math program, was designed and implemented at a college in Toronto, Ontario. Although …
Silica As A Matrix For Encapsulating Proteins:Surface Effects On Protein Structure Assessed By Circular Dichroism Spectroscopy, Daryl K. Eggers, P. J. Calabretta, M. C. Chancellor, C. Torres, G. R. Abel Jr., C. Neihaus, N. J. Birtwhistle, N. M. Khouderchah, G. H. Zemede
Silica As A Matrix For Encapsulating Proteins:Surface Effects On Protein Structure Assessed By Circular Dichroism Spectroscopy, Daryl K. Eggers, P. J. Calabretta, M. C. Chancellor, C. Torres, G. R. Abel Jr., C. Neihaus, N. J. Birtwhistle, N. M. Khouderchah, G. H. Zemede
Faculty Publications, Chemistry
The encapsulation of biomolecules in solid materials that retain the native properties of the molecule is a desired feature for the development of biosensors and biocatalysts. In the current study, protein entrapment in silica-based materials is explored using the sol-gel technique. This work surveys the effects of silica confinement on the structure of several model polypeptides, including apomyoglobin, copper-zinc superoxide dismutase, polyglutamine, polylysine, and type I antifreeze protein. Changes in the secondary structure of each protein following encapsulation are monitored by circular dichroism spectroscopy. In many cases, silica confinement reduces the fraction of properly-folded protein relative to solution, but addition …
Elements Of Proximal Formative Assessment In Learners’ Discourse About Energy, Benedikt W. Harrer, Rachel E. Scherr, Michael C. Wittmann, Hunter G. Close, Brian W. Frank
Elements Of Proximal Formative Assessment In Learners’ Discourse About Energy, Benedikt W. Harrer, Rachel E. Scherr, Michael C. Wittmann, Hunter G. Close, Brian W. Frank
Faculty Publications
Proximal formative assessment, the just-in-time elicitation of students' ideas that informs ongoing instruction, is usually associated with the instructor in a formal classroom setting. However, the elicitation, assessment, and subsequent instruction that characterize proximal formative assessment are also seen in discourse among peers. We present a case in which secondary teachers in a professional development course at SPU are discussing energy flow in refrigerators. In this episode, a peer is invited to share her thinking (elicitation). Her idea that refrigerators move heat from a relatively cold compartment to a hotter environment is inappropriately judged as incorrect (assessment). The "instruction" (peer …
Short-Range Correlations And Cooling Of Ultracold Fermions In The Honeycomb Lattice, Baoming Tang, Thereza Paiva, Ehsan Khatami, Marcos Rigol
Short-Range Correlations And Cooling Of Ultracold Fermions In The Honeycomb Lattice, Baoming Tang, Thereza Paiva, Ehsan Khatami, Marcos Rigol
Faculty Publications
We use determinantal quantum Monte Carlo simulations and numerical linked-cluster expansions to study thermodynamic properties and short-range spin correlations of fermions in the honeycomb lattice. We find that, at half filling and finite temperatures, nearest-neighbor spin correlations can be stronger in this lattice than in the square lattice, even in regimes where the ground state in the former is a semimetal or a spin liquid. The honeycomb lattice also exhibits a more pronounced anomalous region in the double occupancy that leads to stronger adiabatic cooling than in the square lattice. We discuss the implications of these findings for optical lattice …
Numerical Linked-Cluster Expansion For The Distorted Kagome Lattice Heisenberg Model, Ehsan Khatami, Marcos Rigol
Numerical Linked-Cluster Expansion For The Distorted Kagome Lattice Heisenberg Model, Ehsan Khatami, Marcos Rigol
Faculty Publications
Motivated by experimental results for the thermodynamic properties of the Rb2Cu3SnF12 material and the discovery of its valence-bond solid ground state, we utilize the numerical linked-cluster expansions (NLCEs) and devise an expansion tailored to solve the Heisenberg model on a pinwheel-distorted kagome lattice. Using the exchange interactions that are relevant to Rb2Cu3SnF12, we calculate its uniform spin susceptibility and find a very good agreement with experiment. Next, we focus on the ground state of a simplified model of the distorted kagome lattice and take advantage of a zero-temperature Lanczos-based NLCE to study the approach to the ground state of the …
Testing Yukawa-Like Potentials From F(R)-Gravity In Elliptical Galaxies, N. R. Napolitano, S. Capozziello, Aaron J. Romanowsky, M. Capaccioli, C. Tortora
Testing Yukawa-Like Potentials From F(R)-Gravity In Elliptical Galaxies, N. R. Napolitano, S. Capozziello, Aaron J. Romanowsky, M. Capaccioli, C. Tortora
Faculty Publications
We present the first analysis of extended stellar kinematics of elliptical galaxies where a Yukawa-like correction to the Newtonian gravitational potential derived from f(R)-gravity is considered as an alternative to dark matter. In this framework, we model long-slit data and planetary nebula data out to 7 R eff of three galaxies with either decreasing or flat dispersion profiles. We use the corrected Newtonian potential in a dispersion-kurtosis Jeans analysis to account for the mass-anisotropy degeneracy. We find that these modified potentials are able to fit nicely all three elliptical galaxies and the anisotropy distribution is consistent with that estimated if …
Evidence For Inhomogeneous Reionization In The Local Universe From Metal-Poor Globular Cluster Systems, L. R. Spitler, Aaron J. Romanowsky, J. Diemand, J. Strader, D. A. Forbes, B. Moore, J. P. Brodie
Evidence For Inhomogeneous Reionization In The Local Universe From Metal-Poor Globular Cluster Systems, L. R. Spitler, Aaron J. Romanowsky, J. Diemand, J. Strader, D. A. Forbes, B. Moore, J. P. Brodie
Faculty Publications
Exploiting a fundamental characteristic of galaxy assembly in the Λ cold dark matter paradigm, the observed spatial biasing and kinematics of metal-poor globular star clusters are used to constrain the local reionization epoch around individual galaxies. Selecting three galaxies located in different environments, the first attempt at constraining the environmental propagation of reionization in the local Universe is carried out. The joint constraint from the three galaxies (Graphic) agrees remarkably well with the latest Wilkinson Microwave Anisotropy Probe constraint on zreion for a simple instantaneous reionization model. More importantly, the range of zreion values found here is consistent with the …
The Ongoing Assembly Of A Central Cluster Galaxy: Phase-Space Substructures In The Halo Of M87, Aaron J. Romanowsky, J. Strader, J. P. Brodie, C. Mihos, L. R. Spitler, D. A. Forbes, C. Foster, J. A. Arnold
The Ongoing Assembly Of A Central Cluster Galaxy: Phase-Space Substructures In The Halo Of M87, Aaron J. Romanowsky, J. Strader, J. P. Brodie, C. Mihos, L. R. Spitler, D. A. Forbes, C. Foster, J. A. Arnold
Faculty Publications
The halos of galaxies preserve unique records of their formation histories. We carry out the first combined observational and theoretical study of phase-space halo substructure in an early-type galaxy: M87, the central galaxy in the Virgo cluster. We analyze an unprecedented wide-field, high-precision photometric and spectroscopic data set for 488 globular clusters (GCs), which includes new, large-radius Subaru/Suprime-Cam and Keck/DEIMOS observations. We find signatures of two substructures in position-velocity phase space. One is a small, cold stream associated with a known stellar filament in the outer halo; the other is a large shell-like pattern in the inner halo that implies …
The Sluggs Survey: Ngc 3115, A Critical Test Case For Metallicity Bimodality In Globular Cluster Systems, J. P. Brodie, C. Usher, C. Conroy, J. Strader, J. A. Arnold, D. A. Forbes, Aaron J. Romanowsky
The Sluggs Survey: Ngc 3115, A Critical Test Case For Metallicity Bimodality In Globular Cluster Systems, J. P. Brodie, C. Usher, C. Conroy, J. Strader, J. A. Arnold, D. A. Forbes, Aaron J. Romanowsky
Faculty Publications
Due to its proximity (9 Mpc) and the strongly bimodal color distribution of its spectroscopically well-sampled globular cluster (GC) system, the early-type galaxy NGC 3115 provides one of the best available tests of whether the color bimodality widely observed in GC systems generally reflects a true metallicity bimodality. Color bimodality has alternatively been attributed to a strongly nonlinear color-metallicity relation reflecting the influence of hot horizontal-branch stars. Here, we couple Subaru Suprime-Cam gi photometry with Keck/DEIMOS spectroscopy to accurately measure GC colors and a CaT index that measures the Ca II triplet. We find the NGC 3115 GC system to …
The Sluggs Survey: Globular Cluster System Kinematics And Substructure In Ngc 4365, C. Blom, D. A. Forbes, J. P. Brodie, C. Foster, Aaron J. Romanowsky, L. R. Spitler, J. Strader
The Sluggs Survey: Globular Cluster System Kinematics And Substructure In Ngc 4365, C. Blom, D. A. Forbes, J. P. Brodie, C. Foster, Aaron J. Romanowsky, L. R. Spitler, J. Strader
Faculty Publications
We present a kinematic analysis of the globular cluster (GC) system of the giant elliptical galaxy NGC 4365 and find several distinct kinematic substructures. This analysis is carried out using radial velocities for 269 GCs, obtained with the DEIMOS (DEep Imaging Multi-Object Spectrograph) instrument on the Keck II telescope as part of the SAGES Legacy Unifying Globulars and Galaxies Survey (SLUGGS). We find that each of the three (formerly identified) GC colour subpopulations reveal distinct rotation properties. The rotation of the green GC subpopulation is consistent with the bulk of NGC 4365's stellar light, which ‘rolls’ about the photometric major …
The Sluggs Survey: Calcium Triplet-Based Spectroscopic Metallicites For Over 900 Globular Clusters, C. Usher, D. A. Forbes, J. P. Brodie, C. Foster, L. R. Spitler, J. A. Arnold, Aaron J. Romanowsky, J. Strader, V. Pota
The Sluggs Survey: Calcium Triplet-Based Spectroscopic Metallicites For Over 900 Globular Clusters, C. Usher, D. A. Forbes, J. P. Brodie, C. Foster, L. R. Spitler, J. A. Arnold, Aaron J. Romanowsky, J. Strader, V. Pota
Faculty Publications
Although the colour distribution of globular clusters in massive galaxies is well known to be bimodal, the spectroscopic metallicity distribution has been measured in only a few galaxies. After redefining the calcium triplet index–metallicity relation, we use our relation to derive the metallicity of 903 globular clusters in 11 early-type galaxies. This is the largest sample of spectroscopic globular cluster metallicities yet assembled. We compare these metallicities with those derived from Lick indices finding good agreement. In six of the eight galaxies with sufficient numbers of high-quality spectra we find bimodality in the spectroscopic metallicity distribution. Our results imply that …