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Articles 1 - 30 of 33
Full-Text Articles in Physical Sciences and Mathematics
Global Change, Global Trade, And The Next Wave Of Plant Invasions, Bethany A. Bradley, Dana M. Blumenthal, Regan Early, Edwin D. Grosholz, Joshua J. Lawler, Luke P. Miller, Cascade J.B. Sorte, Carla M. D'Antonio, Jeffrey M. Diez, Jeffrey S. Dukes, Ines Ibanez, Julian D. Olden
Global Change, Global Trade, And The Next Wave Of Plant Invasions, Bethany A. Bradley, Dana M. Blumenthal, Regan Early, Edwin D. Grosholz, Joshua J. Lawler, Luke P. Miller, Cascade J.B. Sorte, Carla M. D'Antonio, Jeffrey M. Diez, Jeffrey S. Dukes, Ines Ibanez, Julian D. Olden
Faculty Publications, Biological Sciences
Many non-native plants in the US have become problematic invaders of native and managed ecosystems, but a new generation of invasive species may be at our doorstep. Here, we review trends in the horticultural trade and invasion patterns of previously introduced species and show that novel species introductions from emerging horticultural trade partners are likely to rapidly increase invasion risk. At the same time, climate change and water restrictions are increasing demand for new types of species adapted to warm and dry environments. This confluence of forces could expose the US to a range of new invasive species, including many …
Thermodynamics And Phase Transitions For The Heisenberg Model On The Pinwheel Distorted Kagome Lattice, Ehsan Khatami, Rajiv Singh, Marcos Rigol
Thermodynamics And Phase Transitions For The Heisenberg Model On The Pinwheel Distorted Kagome Lattice, Ehsan Khatami, Rajiv Singh, Marcos Rigol
Faculty Publications
We study the Heisenberg model on the pinwheel distorted kagome lattice as observed in the material Rb2Cu3SnF12. Experimentally relevant thermodynamic properties at finite temperatures are computed utilizing numerical linked-cluster expansions. We also develop a Lanczos-based, zero-temperature, numerical linked-cluster expansion to study the approach of the pinwheel distorted lattice to the uniform kagome-lattice Heisenberg model. We find strong evidence for a phase transition before the uniform limit is reached, implying that the ground state of the kagome-lattice Heisenberg model is likely not pinwheel dimerized and is stable to finite pinwheel-dimerizing perturbations.
Thermodynamics Of Strongly Interacting Fermions In Two-Dimensional Optical Lattices, Ehsan Khatami, Marcos Rigol
Thermodynamics Of Strongly Interacting Fermions In Two-Dimensional Optical Lattices, Ehsan Khatami, Marcos Rigol
Faculty Publications
We study finite-temperature properties of strongly correlated fermions in two-dimensional optical lattices by means of numerical linked cluster expansions, a computational technique that allows one to obtain exact results in the thermodynamic limit. We focus our analysis on the strongly interacting regime, where the on-site repulsion is of the order of or greater than the band width. We compute the equation of state, double occupancy, entropy, uniform susceptibility, and spin correlations for temperatures that are similar to or below the ones achieved in current optical lattice experiments. We provide a quantitative analysis of adiabatic cooling of trapped fermions in two …
Chemical Activity In Yba2cu3o7 − Δ Across The Normal To Superconducting Phase Transition, Juana Vivó Acrivos
Chemical Activity In Yba2cu3o7 − Δ Across The Normal To Superconducting Phase Transition, Juana Vivó Acrivos
Faculty Publications, Chemistry
The Gibbs free enthalpy, chemical activity across the transition temperature to superconductivity, Tc in YBa2Cu3O7 − δ is obtained from reciprocally enhanced X-Ray absorbance, XAS and diffraction, XRD data near the Ba L3,2 edges' energy Ea, and orientations in the X-ray beam for preferred Miller indexed [HKL] planes' scattering, that are enhanced near Tc. The standard enthalpy and entropy for the formation of mixed normal metal/superconducting domains above Tc, determined individually across the two Ba L3,2 edges, to better than a percent accuracy: ΔH≠≥ = − 220 meV, and ΔS≠≥ = − 2 meV/K when 121 ≥ T ≥ 92 …
Hubble Space Telescope Imaging Of Post-Starburst Quasars, S. Cales, M. Brotherton, Zhaohui Shang, Vardha Bennert, Gabriela Canalizo, R. Stoll, R. Ganguly, D. Berk, Cassandra Paul, A. Diamond-Stanic
Hubble Space Telescope Imaging Of Post-Starburst Quasars, S. Cales, M. Brotherton, Zhaohui Shang, Vardha Bennert, Gabriela Canalizo, R. Stoll, R. Ganguly, D. Berk, Cassandra Paul, A. Diamond-Stanic
Faculty Publications
We present images of 29 post-starburst quasars (PSQs) from a Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Wide Field Channel Snapshot program. These broadlined active galactic nuclei (AGNs) possess the spectral signatures of massive (Mburst ∼ 1010 M⊙), moderate-aged stellar populations (hundreds of Myr). Thus, their composite nature provides insight into the AGN–starburst connection. We measure quasar-to-host galaxy light contributions via semi-automated two-dimensional light profile fits of point-spread-function-subtracted images. We examine the host morphologies and model the separate bulge and disk components. The HST/ACS-F606W images reveal an equal number of spiral (13/29) and early-type (13/29) hosts, with the …
Meso-Circulation Associated With Summer Convection Over The Central Antilles, Mark Jury, Sen Chiao
Meso-Circulation Associated With Summer Convection Over The Central Antilles, Mark Jury, Sen Chiao
Faculty Publications, Meteorology and Climate Science
The mesoscale structure of the circulation and convection over central Caribbean Antilles islands in midsummer is analyzed. Afternoon thunderstorms are frequent over islands such as Hispaniola and Jamaica as confluent trade winds circulate over heated mountainous topography. Observational data from a rain gauge network, profiles from aircraft and radiosonde, satellite estimates of rainfall, and mesoscale reanalysis fields are studied with a focus on July 2007. A statistical decomposition of 3-hourly high-resolution satellite rainfall reveals an “island mode” with afternoon convection. Trade winds pass over the mountains of Hispaniola and Jamaica with a Froude number <1, leading to a long meandering wake. The Weather Research and Forecasting model is used to simulate climatic conditions during July 2007. The model correctly locates areas of diurnal rainfall that develop because of island heat fluxes, confluent sea breezes, and mountain wakes.
Rumbling In The Benthos: Acoustic Ecology Of The California Mantis Shrimp Hemisquilla Californiensis, E. Staaterman, C. Clark, A. Gallagher, M. Devries, T. Claverie, S. Patek
Rumbling In The Benthos: Acoustic Ecology Of The California Mantis Shrimp Hemisquilla Californiensis, E. Staaterman, C. Clark, A. Gallagher, M. Devries, T. Claverie, S. Patek
Faculty Publications, Biological Sciences
Although much research has focused on acoustic mapping and exploration of the benthic environment, little is known about the acoustic ecology of benthic organisms, particularly benthic crustaceans. Through the use of a coupled audio–video system, a hydrophone array, and an autonomous recording unit, we tested several hypotheses about the field acoustics of a benthic marine crustacean, Hemisquilla californiensis. Living in muddy burrows in southern California, these large mantis shrimp produce low frequency ‘rumbles’ through muscle vibrations. First, we tested whether acoustic signals are similar in the field and in the laboratory, and discovered that field-produced rumbles are more acoustically and …
Efficient Unfolding Pattern Recognition In Single Molecule Force Spectroscopy Data, Bill Andreopoulos, Dirk Labudde
Efficient Unfolding Pattern Recognition In Single Molecule Force Spectroscopy Data, Bill Andreopoulos, Dirk Labudde
Faculty Publications, Computer Science
BackgroundSingle-molecule force spectroscopy (SMFS) is a technique that measures the force necessary to unfold a protein. SMFS experiments generate Force-Distance (F-D) curves. A statistical analysis of a set of F-D curves reveals different unfolding pathways. Information on protein structure, conformation, functional states, and inter- and intra-molecular interactions can be derived.ResultsIn the present work, we propose a pattern recognition algorithm and apply our algorithm to datasets from SMFS experiments on the membrane protein bacterioRhodopsin (bR). We discuss the unfolding pathways found in bR, which are characterised by main peaks and side peaks. A main peak is the result of the pairwise …
Making Connections Between Science And Equity: A Motivation To Teach Science In Elementary Grades, Grinell Smith, Colette Rabin
Making Connections Between Science And Equity: A Motivation To Teach Science In Elementary Grades, Grinell Smith, Colette Rabin
Faculty Publications
Teacher quality is among the strongest correlates of student outcomes. However, only about a quarter of the nation’s elementary teachers consider themselves qualified to teach science. In this descriptive and exploratory study, we investigated whether helping pre-service teacher candidates explore connections between science and issues of equity, particularly around sustainability issues, could help them see the importance of teaching science to their students more often. Qualitative and quantitative data were collected from 59 students enrolled in revised science methods courses at a large public university. Our findings suggest that positioning science instruction thusly was perceived as a strong motivator to …
Thermodynamics Of The Antiferromagnetic Heisenberg Model On The Checkerboard Lattice, Ehsan Khatami, Maros Rigol
Thermodynamics Of The Antiferromagnetic Heisenberg Model On The Checkerboard Lattice, Ehsan Khatami, Maros Rigol
Faculty Publications
Employing numerical linked-cluster expansions (NLCEs) along with exact diagonalizations of finite clusters with periodic boundary condition, we study the energy, specific heat, entropy, and various susceptibilities of the antiferromagnetic Heisenberg model on the checkerboard lattice. NLCEs, combined with extrapolation techniques, allow us to access temperatures much lower than those accessible to exact diagonalization and other series expansions. We show that the high-temperature peak in specific heat decreases as the frustration increases, consistent with the large amount of unquenched entropy in the region around maximum classical frustration, where the nearest-neighbor and next-nearest-neighbor exchange interactions (J and J′, respectively) have the same …
Quantum Criticality And Incipient Phase Separation In The Thermodynamic Properties Of The Hubbard Model, D. Galanakis, Ehsan Khatami, K. Mikelsons, A. Macridin, J. Moreno, D. Browne, M. Jarrell
Quantum Criticality And Incipient Phase Separation In The Thermodynamic Properties Of The Hubbard Model, D. Galanakis, Ehsan Khatami, K. Mikelsons, A. Macridin, J. Moreno, D. Browne, M. Jarrell
Faculty Publications
Transport measurements on the cuprates suggest the presence of a quantum critical point (QCP) hiding underneath the superconducting dome near optimal hole doping. We provide numerical evidence in support of this scenario via a dynamical cluster quantum Monte Carlo study of the extended two-dimensional Hubbard model. Single-particle quantities, such as the spectral function, the quasi-particle weight and the entropy, display a crossover between two distinct ground states: a Fermi liquid at low filling and a non-Fermi liquid with a pseudo-gap at high filling. Both states are found to cross over to a marginal Fermi-liquid state at higher temperatures. For finite …
Comparisons Of Vcsel And Airs/Amsu-A On Water Vapor And Temperature In Hippo#1, Minghui Diao, Mark Zondlo, Loayeh Jumbah, Justin Sheffield, Eric Wood
Comparisons Of Vcsel And Airs/Amsu-A On Water Vapor And Temperature In Hippo#1, Minghui Diao, Mark Zondlo, Loayeh Jumbah, Justin Sheffield, Eric Wood
Faculty Publications, Meteorology and Climate Science
No abstract available.
The Effect Of Zonally Asymmetric Ozone Heating On The Northern Hemisphere Winter Polar Stratosphere, J. P. Mccormack, T. R. Nathan, E. C. Cordero
The Effect Of Zonally Asymmetric Ozone Heating On The Northern Hemisphere Winter Polar Stratosphere, J. P. Mccormack, T. R. Nathan, E. C. Cordero
Faculty Publications, Meteorology and Climate Science
[1] Previous modeling studies have found significant differences in winter extratropical stratospheric temperatures depending on the presence or absence of zonally asymmetric ozone heating (ZAOH), yet the physical mechanism causing these differences has not been fully explained. The present study describes the effect of ZAOH on the dynamics of the Northern Hemisphere extratropical stratosphere using an ensemble of free-running atmospheric general circulation model simulations over the 1 December - 31 March period. We find that the simulations including ZAOH produce a significantly warmer and weaker stratospheric polar vortex in mid-February due to more frequent major stratospheric sudden warmings compared to …
Fire Whirl Evolution Observed During A Valley Wind-Sea Breeze Reversal, Daisuke Seto, Craig B. Clements
Fire Whirl Evolution Observed During A Valley Wind-Sea Breeze Reversal, Daisuke Seto, Craig B. Clements
Faculty Publications, Meteorology and Climate Science
This observational study documented the atmospheric environment of a prescribed fire conducted in a narrow valley when a small fire whirl developed during a mesoscale wind reversal. Based on analysis of in situ meteorological measurements, it is hypothesized that the fire whirl formed due to the presence of strong vertical wind shear caused by the interaction of a sea breeze front with a weaker up-valley wind. Vorticity generated by the interaction of the wind shear and the fire front was estimated to be ~0.2 s−1. Peak turbulence kinetic energy was caused by the wind shear rather than the buoyancy generated …
Synthesis Of Knowledge Of Extreme Fire Behavior: Volume I For Fire Managers, Paul Werth, Brian Potter, Craig Clements, Mark Finney, Scott Goodrick, Martin Alexander, Miguel Cruz, Jason Forthofer, Sara Mcallister
Synthesis Of Knowledge Of Extreme Fire Behavior: Volume I For Fire Managers, Paul Werth, Brian Potter, Craig Clements, Mark Finney, Scott Goodrick, Martin Alexander, Miguel Cruz, Jason Forthofer, Sara Mcallister
Faculty Publications, Meteorology and Climate Science
The National Wildfire Coordinating Group definition of extreme fire behavior (EFB) indicates a level of fire behavior characteristics that ordinarily precludes methods of direct control action. One or more of the following is usually involved: high rate of spread, prolific crowning/ spotting, presence of fire whirls, and strong convection column. Predictability is difficult because such fires often exercise some degree of influence on their environment and behave erratically, sometimes dangerously. Alternate terms include “blow up” and “fire storm.” Fire managers examining fires over the last 100 years have come to understand many of the factors necessary for EFB development. This …
A Bulk Water-Dependent Desolvation Energy Model For Analyzing The Effects Of Secondary Solutes On Biological Equilibria, Daryl K. Eggers
A Bulk Water-Dependent Desolvation Energy Model For Analyzing The Effects Of Secondary Solutes On Biological Equilibria, Daryl K. Eggers
Faculty Publications, Chemistry
A new phenomenological model for interpreting the effects of solutes on biological equilibria is presented. The model attributes changes in equilibria to differences in the desolvation energy of the reacting species that, in turn, reflect changes in the free energy of the bulk water upon addition of secondary solutes. The desolvation approach differs notably from that of other solute models by treating the free energy of bulk water as a variable and by not ascribing the observed shifts in reaction equilibria to accumulation or depletion of solutes next to the surfaces of the reacting species. On the contrary, the partitioning …
Diffusive Transport Enhanced By Thermal Velocity Fluctuations, Alejandro Garcia, A. Donev, A. De La Fuente, J. B. Bell
Diffusive Transport Enhanced By Thermal Velocity Fluctuations, Alejandro Garcia, A. Donev, A. De La Fuente, J. B. Bell
Faculty Publications
We study the contribution of advection by thermal velocity fluctuations to the effective diffusion coefficient in a mixture of two identical fluids. We find good agreement between a simple fluctuating hydrodynamics theory and particle and finite-volume simulations. The enhancement of the diffusive transport depends on the system size L and grows as ln(L/L0) in quasi-two-dimensional systems, while in three dimensions it scales as L0-1-L-1, where L0 is a reference length. Our results demonstrate that fluctuations play an important role in the hydrodynamics of small-scale systems.
Unravelling The Origins Of S0 Galaxies Using Maximum Likelihood Analysis Of Planetary Nebulae Kinematics, A. Cortesi, M. R. Merrifield, M. Arnaboldi, O. Gerhard, I. Martinez-Valpuesta, K. Saha, L. Coccato, S. Bamford, N. R. Napolitano, N. G. Douglas, Aaron J. Romanowsky, K. Kuijken, M. Capaccioli, K. C. Freeman
Unravelling The Origins Of S0 Galaxies Using Maximum Likelihood Analysis Of Planetary Nebulae Kinematics, A. Cortesi, M. R. Merrifield, M. Arnaboldi, O. Gerhard, I. Martinez-Valpuesta, K. Saha, L. Coccato, S. Bamford, N. R. Napolitano, N. G. Douglas, Aaron J. Romanowsky, K. Kuijken, M. Capaccioli, K. C. Freeman
Faculty Publications
To investigate the origins of S0 galaxies, we present a new method of analysing their stellar kinematics from discrete tracers such as planetary nebulae. This method involves binning the data in the radial direction so as to extract the most general possible non-parametric kinematic profiles, and using a maximum-likelihood fit within each bin in order to make full use of the information in the discrete kinematic tracers. Both disc and spheroid kinematic components are fitted, with a two-dimensional decomposition of imaging data used to attribute to each tracer a probability of membership in the separate components. Likelihood clipping also allows …
Wide-Field Precision Kinematics Of The M87 Globular Cluster System, J. Strader, Aaron J. Romanowsky, J. P. Brodie, L. R. Spitler, M. A. Beasley, Jacob A. Arnold, N. Tamura, R. M. Sharples, N. Arimoto
Wide-Field Precision Kinematics Of The M87 Globular Cluster System, J. Strader, Aaron J. Romanowsky, J. P. Brodie, L. R. Spitler, M. A. Beasley, Jacob A. Arnold, N. Tamura, R. M. Sharples, N. Arimoto
Faculty Publications
We present the most extensive combined photometric and spectroscopic study to date of the enormous globular cluster (GC) system around M87, the central giant elliptical galaxy in the nearby Virgo Cluster. Using observations from DEIMOS and the Low Resolution Imaging Spectrometer at Keck, and Hectospec on the Multiple Mirror Telescope, we derive new, precise radial velocities for 451 GCs around M87, with projected radii from ~5 to 185 kpc. We combine these measurements with literature data for a total sample of 737 objects, which we use for a re-examination of the kinematics of the GC system of M87. The velocities …
The Pn.S Elliptical Galaxy Survey: A Standard Cdm Halo Around Ngc 4374?, N. R. Napolitano, Aaron J. Romanowsky, M. Capaccioli, N. G. Douglas, M. Arnaboldi, L. Coccato, O. Gerhard, K. Kuijken, M. R. Merrifield, S. P. Bamford, A. Cortesi, P. Das, K. C. Freeman
The Pn.S Elliptical Galaxy Survey: A Standard Cdm Halo Around Ngc 4374?, N. R. Napolitano, Aaron J. Romanowsky, M. Capaccioli, N. G. Douglas, M. Arnaboldi, L. Coccato, O. Gerhard, K. Kuijken, M. R. Merrifield, S. P. Bamford, A. Cortesi, P. Das, K. C. Freeman
Faculty Publications
As part of our current programme to test ΛCDM predictions for dark matter (DM) haloes using extended kinematical observations of early-type galaxies, we present a dynamical analysis of the bright elliptical galaxy NGC 4374 (M84) based on ∼450 planetary nebulae (PNe) velocities from the PN.Spectrograph, along with extended long-slit stellar kinematics. This is the first such analysis of a galaxy from our survey with a radially constant velocity dispersion profile. We find that the spatial and kinematical distributions of the PNe agree with the field stars in the region of overlap. The velocity kurtosis is consistent with zero at almost …
Stellar Mass-To-Light Ratio Gradients In Galaxies: Correlations With Mass, C. Tortora, N. R. Napolitano, Aaron J. Romanowsky, Ph. Jetzer, V. F. Cardone, M. Capaccioli
Stellar Mass-To-Light Ratio Gradients In Galaxies: Correlations With Mass, C. Tortora, N. R. Napolitano, Aaron J. Romanowsky, Ph. Jetzer, V. F. Cardone, M. Capaccioli
Faculty Publications
We analyse the stellar mass-to-light ratio (M/L) gradients in a large sample of local galaxies taken from the Sloan Digital Sky Survey, spanning a wide range of stellar masses and morphological types. As suggested by the well-known relationship between M/L values and colours, we show that M/L gradients are strongly correlated with colour gradients, which we trace to the effects of age variations. Stellar M/L gradients generally follow patterns of variation with stellar mass and galaxy type that were previously found for colour and metallicity gradients. In late-type galaxies M/L gradients are negative, steepening with increasing mass. In early-type galaxies …
Evidence For Two Phases Of Galaxy Formation From Radial Trends In The Globular Cluster System Of Ngc 1407, D. A. Forbes, L. R. Spitler, J. Strader, Aaron J. Romanowsky, J. P. Brodie, C. Foster
Evidence For Two Phases Of Galaxy Formation From Radial Trends In The Globular Cluster System Of Ngc 1407, D. A. Forbes, L. R. Spitler, J. Strader, Aaron J. Romanowsky, J. P. Brodie, C. Foster
Faculty Publications
Here we present the colours of individual globular clusters (GCs) around the massive elliptical galaxy NGC 1407 out to a projected galactocentric radius of 140 kpc or 17 galaxy effective radii (Re). Such data are a proxy for the halo metallicity. We find steep, and similar, metallicity gradients of ∼−0.4 dex dex−1 for both the blue (metal poor) and red (metal rich) GC subpopulations within 5–8.5 Re (40–70 kpc). At larger radii the mean GC colours (metallicity) are constant. A similar behaviour is seen in a wide-field study of M87's GC system, and in our own Galaxy. We interpret these …
An Extremely Luminous Panchromatic Outburst From The Nucleus Of A Distant Galaxy, A. J. Levan, N. R. Tanvir, S. B. Cenko, D. A. Perley, K. Wiersema, J. S. Bloom, A. S. Fruchter, A. De Urgarte Postigo, P. T. Butler, A. J. Van Der Horst, G. Leloudas, A. N. Morgan, K. Misra, G. C. Bower, J. Farihi, R. L. Tunnicliffe, A. N. Morgan, K. Misra, G. C. Bower, J. Farihi, R. L. Tunnicliffe, M. Modjaz, J. M. Silverman, J. Hjorth, C. Thone, A. Cucchiara, J. M. Castro-Ceron, A. J. Castro-Tirado, J. A. Arnold, M. Bremer, J. P. Brodie, T. Carroll, M. C. Cooper, P. A. Curran, R. M. Cutri, J. Ehle, D. Forbes, J. Fynbo, J. Gorosabel, J. Graham, D. I. Hoffman, S. Guziy, P. Jakobsson, A. Kamble, T. Kerr, M. M. Kasliwal, C. Kouveliotou, D. Kocevski, N. M. Law, P. E. Nugent, E. O. Ofek, D. Poznanski, R. M. Quimby, E. Rol, Aaron J. Romanowsky, R. Sanchez-Ramirez, S. Schulze, N. Singh, L. Van Spaandonk, R.L.C. Starling, R. G. Strom, J. C. Tello, O. Vaduvescu, P. J. Wheatley, J. M. Winters, R.A.M.J. Wijers, D. Xu
An Extremely Luminous Panchromatic Outburst From The Nucleus Of A Distant Galaxy, A. J. Levan, N. R. Tanvir, S. B. Cenko, D. A. Perley, K. Wiersema, J. S. Bloom, A. S. Fruchter, A. De Urgarte Postigo, P. T. Butler, A. J. Van Der Horst, G. Leloudas, A. N. Morgan, K. Misra, G. C. Bower, J. Farihi, R. L. Tunnicliffe, A. N. Morgan, K. Misra, G. C. Bower, J. Farihi, R. L. Tunnicliffe, M. Modjaz, J. M. Silverman, J. Hjorth, C. Thone, A. Cucchiara, J. M. Castro-Ceron, A. J. Castro-Tirado, J. A. Arnold, M. Bremer, J. P. Brodie, T. Carroll, M. C. Cooper, P. A. Curran, R. M. Cutri, J. Ehle, D. Forbes, J. Fynbo, J. Gorosabel, J. Graham, D. I. Hoffman, S. Guziy, P. Jakobsson, A. Kamble, T. Kerr, M. M. Kasliwal, C. Kouveliotou, D. Kocevski, N. M. Law, P. E. Nugent, E. O. Ofek, D. Poznanski, R. M. Quimby, E. Rol, Aaron J. Romanowsky, R. Sanchez-Ramirez, S. Schulze, N. Singh, L. Van Spaandonk, R.L.C. Starling, R. G. Strom, J. C. Tello, O. Vaduvescu, P. J. Wheatley, J. M. Winters, R.A.M.J. Wijers, D. Xu
Faculty Publications
Variable x-ray and γ-ray emission is characteristic of the most extreme physical processes in the universe. We present multiwavelength observations of a unique γ-ray–selected transient detected by the Swift satellite, accompanied by bright emission across the electromagnetic spectrum, and whose properties are unlike any previously observed source. We pinpoint the event to the center of a small, star-forming galaxy at redshift z = 0.3534. Its high-energy emission has lasted much longer than any γ-ray burst, whereas its peak luminosity was ∼100 times higher than bright active galactic nuclei. The association of the outburst with the center of its host galaxy …
The Fossil Record Of Two-Phase Galaxy Assembly: Kinematics And Metallicities In The Nearest S0 Galaxy, J, A, Arnold, Aaron J. Romanowsky, J. P. Brodie, L. Chomiuk, L. R. Spitler, J. Strader, A. J. Benson, D. A. Forbes
The Fossil Record Of Two-Phase Galaxy Assembly: Kinematics And Metallicities In The Nearest S0 Galaxy, J, A, Arnold, Aaron J. Romanowsky, J. P. Brodie, L. Chomiuk, L. R. Spitler, J. Strader, A. J. Benson, D. A. Forbes
Faculty Publications
We present a global analysis of kinematics and metallicity in the nearest S0 galaxy, NGC 3115, along with implications for its assembly history. The data include high-quality wide-field imaging from Suprime-Cam on the Subaru telescope, and multi-slit spectra of the field stars and globular clusters (GCs) obtained using Keck-DEIMOS/LRIS and Magellan-IMACS. Within two effective radii, the bulge (as traced by the stars and metal-rich GCs) is flattened and rotates rapidly (v/σ gsim 1.5). At larger radii, the rotation declines dramatically to v/σ ~ 0.7, but remains well aligned with the inner regions. The radial decrease in characteristic metallicity of both …
Global Properties Of ‘Ordinary’ Early-Type Galaxies: Photometry And Spectroscopy Of Stars And Globular Clusters In Ngc 4494, C. Foster, L. R. Spitler, Aaron J. Romanowsky, D. A. Forbes, V. Pota, K. Bekki, J. Strader, R. N. Proctor, J. A. Arnold, J. P. Brodie
Global Properties Of ‘Ordinary’ Early-Type Galaxies: Photometry And Spectroscopy Of Stars And Globular Clusters In Ngc 4494, C. Foster, L. R. Spitler, Aaron J. Romanowsky, D. A. Forbes, V. Pota, K. Bekki, J. Strader, R. N. Proctor, J. A. Arnold, J. P. Brodie
Faculty Publications
We present a comprehensive analysis of the spatial, kinematic and chemical properties of stars and globular clusters (GCs) in the ‘ordinary’ elliptical galaxy NGC 4494 using data from the Keck and Subaru telescopes. We derive galaxy surface brightness and colour profiles out to large galactocentric radii. We compare the latter to metallicities derived using the near-infrared Calcium Triplet. We obtain stellar kinematics out to ∼3.5 effective radii. The latter appear flattened or elongated beyond ∼1.8 effective radii in contrast to the relatively round photometric isophotes. In fact, NGC 4494 may be a flattened galaxy, possibly even an S0, seen at …
Star Clusters In M31: Old Clusters With Bar Kinematics, H. Morrison, N. Caldwell, R. P. Schiavon, E. Athanassoula, Aaron J. Romanowsky, P. Harding
Star Clusters In M31: Old Clusters With Bar Kinematics, H. Morrison, N. Caldwell, R. P. Schiavon, E. Athanassoula, Aaron J. Romanowsky, P. Harding
Faculty Publications
We analyze our accurate kinematical data for the old clusters in the inner regions of M31. These velocities are based on high signal-to-noise Hectospec data. The data are well suited for analysis of M31's inner regions because we took particular care to correct for contamination by unresolved field stars from the disk and bulge in the fibers. The metal-poor clusters show kinematics that are compatible with a pressure-supported spheroid. The kinematics of metal-rich clusters, however, argue for a disk population. In particular the innermost region (inside 2 kpc) shows the kinematics of the x 2 family of bar periodic orbits, …
The Dark Halo Of He Hydra I Galaxy Cluster: Core, Cusp, Cosmological? Dynamics Of Ngc 3311 And Its Globular Cluster System, T. Richtler, R. Salinas, I. Misgeld, M. Hilker, G.K. T. Hau, Aaron J. Romanowsky, Y. Schuberth, M. Spolaor
The Dark Halo Of He Hydra I Galaxy Cluster: Core, Cusp, Cosmological? Dynamics Of Ngc 3311 And Its Globular Cluster System, T. Richtler, R. Salinas, I. Misgeld, M. Hilker, G.K. T. Hau, Aaron J. Romanowsky, Y. Schuberth, M. Spolaor
Faculty Publications
Context. Some galaxy clusters exhibit shallow or even cored dark matter density profiles in their central regions rather than the predicted steep or cuspy profiles, conflicting with the standard understanding of dark matter. NGC 3311 is the central cD galaxy of the Hydra I cluster (Abell 1060). Aims. We use globular clusters around NGC 3311, combined with kinematical data of the galaxy itself, to investigate the dark matter distribution in the central region of Hydra I. Methods. Radial velocities of 118 bright globular clusters, based on VLT/VIMOS mask spectroscopy, are used to calculate velocity dispersions which are well defined out …
Crazy Heart: Kinematics Of The “Star Pile” In Abell 545, R. Salinas, T. Richtler, M. J. West, Aaron J. Romanowsky, E. Llyod-Davies, Y. Schuberth
Crazy Heart: Kinematics Of The “Star Pile” In Abell 545, R. Salinas, T. Richtler, M. J. West, Aaron J. Romanowsky, E. Llyod-Davies, Y. Schuberth
Faculty Publications
We study the structure and internal kinematics of the “star pile” in Abell 545 – a low surface brightness structure lying in the center of the cluster. We have obtained deep long-slit spectroscopy of the star pile using VLT/FORS2 and Gemini/GMOS, which is analyzed in conjunction with deep multiband CFHT/MEGACAM imaging. As presented in a previous study the star pile has a flat luminosity profile and its color is consistent with the outer parts of elliptical galaxies. Its velocity map is irregular, with parts being seemingly associated with an embedded nucleus, and others which have significant velocity offsets to the …
Galaxies In Cdm With Halo Abundance Matching: Luminosity-Velocity Relation, Baryonic Mass-Velocity Relation, Velocity Function, And Clustering, S. Trujillo-Gomez, A. Klypin, J. Primack, Aaron J. Romanowsky
Galaxies In Cdm With Halo Abundance Matching: Luminosity-Velocity Relation, Baryonic Mass-Velocity Relation, Velocity Function, And Clustering, S. Trujillo-Gomez, A. Klypin, J. Primack, Aaron J. Romanowsky
Faculty Publications
It has long been regarded as difficult if not impossible for a cosmological model to account simultaneously for the galaxy luminosity, mass, and velocity distributions. We revisit this issue using a modern compilation of observational data along with the best available large-scale cosmological simulation of dark matter (DM). We find that the standard cosmological model, used in conjunction with halo abundance matching (HAM) and simple dynamical corrections, fits—at least on average—all basic statistics of galaxies with circular velocities V circ > 80 km s–1 calculated at a radius of ~10 kpc. Our primary observational constraint is the luminosity-velocity (LV) relation—which generalizes …
Speciation, Luminescence, And Alkaline Fluorescence Quenching Of 4-(2-Methylbutyl)Aminodipicolinic Acid (H2mebadpa), Gilles Muller, A. J. Ingram, A. G. Dunpal, R. Dipietro
Speciation, Luminescence, And Alkaline Fluorescence Quenching Of 4-(2-Methylbutyl)Aminodipicolinic Acid (H2mebadpa), Gilles Muller, A. J. Ingram, A. G. Dunpal, R. Dipietro
Faculty Publications, Chemistry
4-(2-Methylbutyl)aminodipicolinic acid (H2MEBADPA) has been synthesized and fully characterized in terms of aqueous phase protonation constants (pKa's) and photophysical measurements. The pKa's were determined by spectrophotometric titrations, utilizing a fully sealed titration system. Photophysical measurements consisted of room temperature fluorescence and frozen solution phosphorescence as well as quantum yield determinations at various pH, which showed that only fully deprotonated MEBADPA2– is appreciably emissive. The fluorescence of MEBADPA2– has been determined to be quenched by hydroxide and methoxide anions, most likely through base-catalyzed excited-state tautomerism or proton transfer. This quenching phenomenon has been quantitatively explored through steady-state and time-resolved fluorescence measurements. …