Astrophysics and Astronomy Commons^™

Three Candidate Clusters Around High Redshift Radio-Loud Sources: Mg1 J04426+0202, 3c 068.2, And Ms 1426.9+1052, J. R. Franck, Stacy S. Mcgaugh

Faculty Scholarship

We present near-infrared observations of the environments around three radio-loud sources (MG1 J0442+0202, 3C 068.2, and MS 1426.9+1052) at redshifts z = 1.10, 1.57, and 1.83 (respectively).,Qthat are surrounded by nearinfrared galaxy overdensities. Overdensities with respect to field counts were found to be significant up to 19£m, with 12 times the expected number of galaxies within the inner regions of the densest proto-cluster. Color¡V magnitude relations are constructed in Ks, J . Ks, with each candidate cluster exhibiting a feature consistent with the beginnings of a red sequence (RS). Galaxy models based on the redshift of the radio source are …

Simulating Correlated Disorder In Spin Glass, Jared D. Willard

Macalester Journal of Physics and Astronomy

Almost all materials undergo spontaneous symmetry breaking at sufficiently low

temperatures. For most magnetic materials, the spin rotational symmetry is broken

to form magnetic ordering. The discovery of metallic alloys which fail to form

conventional magnetic order has remained a puzzle for the last few decades.

Unfortunately, analytical calculations cannot provide an unbiased answer for the

problem. Furthermore, on the numerical side, Monte Carlo simulations require

extremely long equilibration times. The parallel tempering method has proven a

powerful tool to alleviate the long equilibration time. With the extensive efforts of

numerical simulation research, some of the idealized models have been …

Supermassive Black Hole Formation At High Redshifts Via Direct Collapse In A Cosmological Context, Jun-Hwan Choi, Isaac Shlosman, Mitchell C. Begelman

Physics and Astronomy Faculty Publications

We study the early stage of the formation of seed supermassive black holes via direct collapse in dark matter (DM) haloes, in the cosmological context. We perform high-resolution zoom-in simulations of such collapse at high z. Using the adaptive mesh refinement code enzo, we resolve the formation and growth of a DM halo, until its virial temperature reaches ∼10⁴ K, atomic cooling turns on, and collapse ensues. We demonstrate that direct collapse proceeds in two stages, although they are not well separated. The first stage is triggered by the onset of atomic cooling, and leads to rapidly increasing …

Extragalactic Explorers: Professors Elizabeth Mcgrath And Dale Kocevski Divine The Mysteries Of The Universe, Gerry Boyle

Colby Magazine

From their offices on the fourth floor of the Mudd Science Building, Elizabeth McGrath and Dale Kocevski enjoy a view that takes in the terraced lawn of the academic quad, the rooftops of Lovejoy and Cotter Union- and distant galaxies as they appeared when the universe was young.

A Re-Interpretation Of The Triangulum-Andromeda Stellar Clouds: A Population Of Halo Stars Kicked Out Of The Galactic Disk, Adrian M. Price-Whelan, Kathryn V. Johnston, Allyson A. Sheffield, Chervin F. P. Laporte, Branimir Sesar

Publications and Research

The Triangulum–Andromeda stellar clouds (TriAnd1 and TriAnd2) are a pair of concentric ring- or shell-like overdensities at large R (≈30 kpc) and Z (≈−10 kpc) in the Galactic halo that are thought to have been formed from the accretion and disruption of a satellite galaxy. This paper critically reexamines this formation scenario by comparing the number ratio of RR Lyrae to M giant stars associated with the TriAnd clouds with other structures in the Galaxy. The current data suggest a stellar population for these overdensities (fRR: MG < 0.38 at 95 per cent confidence) quite unlike any of the known satellites of the Milky Way (fRR: MG ≈ 0.5 for the very largest and f …

Stout: Cloudy's Atomic And Molecular Database, Matt L. Lykins, Gary J. Ferland, R. Kisielius, Marios Chatzikos, R. L. Porter, P. A. M. Van Hoof, R. J. R. Williams, F. P. Keenan, P. C. Stancil

Physics and Astronomy Faculty Publications

We describe a new atomic and molecular database we developed for use in the spectral synthesis code Cloudy. The design of Stout is driven by the data needs of Cloudy, which simulates molecular, atomic, and ionized gas with kinetic temperatures 2.8 K < T <10¹⁰ K and densities spanning the low-to high-density limits. The radiation field between photon energies 10⁻⁸ Ry and 100 MeV is considered, along with all atoms and ions of the lightest 30 elements, and ~10² molecules. For ease of maintenance, the data are stored in a format as close as possible to the original data …

Probing Wolf–Rayet Winds: Chandra/Hetg X-Ray Spectra Of Wr 6, David P. Huenemoerder, K. G. Gayley, Wolf-Rainer Hamann, Richard Ignace, J. S. Nichols, Lidia M. Oskinova, A. M.T. Pollock, Nobert S. Schulz, Tomer Shenar

ETSU Faculty Works

With a deep Chandra/HETGS exposure of WR 6, we have resolved emission lines whose profiles show that the X-rays originate from a uniformly expanding spherical wind of high X-ray-continuum optical depth. The presence of strong helium-like forbidden lines places the source of X-ray emission at tens to hundreds of stellar radii from the photosphere. Variability was present in X-rays and simultaneous optical photometry, but neither were correlated with the known period of the system or with each other. An enhanced abundance of sodium revealed nuclear-processed material, a quantity related to the evolutionary state of the star. The characterization of …

Higgs Shifts From Electron–Positron Annihilations Near Neutron Stars, Gary A. Wegner, Roberto Onofrio

Dartmouth Scholarship

We discuss the potential for using neutron stars to determine bounds on the Higgs-Kretschmann coupling by looking at peculiar shifts in gamma-ray spectroscopic features. In particular, we reanalyze multiple lines observed in GRB781119 detected by two gamma-ray spectrometers, and derive an upper bound on the Higgs-Kretschmann coupling that is much more constraining than the one recently obtained from white dwarfs. This calls for targeted analyses of spectra of gamma-ray bursts from more recent observatories, dedicated searches for differential shifts on electron–positron and proton–antiproton annihilation spectra in proximity of compact sources, and signals of electron and proton cyclotron lines from the …

The Sluggs Survey: Multipopulation Dynamical Modelling Of The Elliptical Galaxy Ngc 1407 From Stars And Globular Clusters, Vincenzo Pota, Aaron Romanowsky, Jean Brodie, Jorge Peñarrubia, Duncan Forbes, Nicola Napolitano, Caroline Foster, Matthew Walker, Jay Strader, Joel Roediger

Faculty Publications

No abstract provided.

Binary Central Stars Of Planetary Nebulae Discovered Through Photometric Variability. Iii. The Central Star Of Abell 65, Todd Hillwig, David J. Frew, Melissa Louie, Orsola De Marco, Sam Schaub

Physics and Astronomy Faculty Publications

A growing number of close binary stars are being discovered among central stars of planetary nebulae. Recent and ongoing surveys are finding new systems and contributing to our knowledge of the evolution of close binary systems. The push to find more systems was largely based on early discoveries which suggested that 10%–15% of all central stars are close binaries. One goal of this series of papers is confirmation and classification of these systems as close binaries and determination of binary system parameters. Here we provide time-resolved multi-wavelength photometry of the central star of Abell 65 as well as further analysis …

Kelt-7b: A Hot Jupiter Transiting A Bright V = 8.54 Rapidly Rotating F-Star, A. Bieryla, K. Collins, T. G. Beatty, J. Eastman, R. J. Siverd, J. Pepper, B. S. Gaudi, K. G. Stassun, C. Cañas, D. W. Latham, L. A. Buchhave, R. Sanchis-Ojeda, J. N. Winn, Eric L.N. Jensen, J. F. Kielkopf, K. K. Mcleod, J. Gregorio, K. D. Colón, R. Street, R. Ross, M. Penny, S. N. Mellon, T. E. Oberst, B. J. Fulton, J. Wang, P. Berlind, M. L. Calkins, G. A. Esquerdo, D. L. Depoy, A. Gould, J. Marshall, R. Pogge, M. Trueblood, P. Trueblood

Physics & Astronomy Faculty Works

We report the discovery of KELT-7b, a transiting hot Jupiter with a mass of 1.28+/- 0.18 M_J, radius of {1.533}_-0.047^+0.046 R_J, and an orbital period of 2.7347749+/- 0.0000039 days. The bright host star (HD 33643; KELT-7) is an F-star with V = 8.54, T_eff = 6789{}_-49⁺⁵⁰ K, [Fe/H] = {0.139}_-0.081^+0.075, and {log}\{\text{}}g\=4.149+/- 0.019. It has a mass of {1.535}_-0.054^+0.066 M_☉, a radius of {1.732}_-0.045^+0.043 R_☉, and is the fifth most massive, fifth hottest, and the ninth brightest star known to …

Comparing Theory And Experiment For Analyte Transport In The First Vacuum Stage Of The Inductively Coupled Plasma Mass Spectrometer, Matthew R. Zachreson

Theses and Dissertations

The inductively coupled plasma mass spectrometer (ICP-MS) has been used in laboratories for many years. The majority of the improvements to the instrument have been done empirically through trial and error. A few fluid models have been made, which have given a general description of the flow through the mass spectrometer interface. However, due to long mean free path effects and other factors, it is very difficult to simulate the flow details well enough to predict how changing the interface design will change the formation of the ion beam. Towards this end, Spencer et al. developed FENIX, a direct simulation …

Beam-Energy-Dependent Two-Pion Interferometry And The Freeze-Out Eccentricity Of Pions Measured In Heavy Ion Collisions At The Star Detector, J. Kevin Adkins, Renee Fatemi, Suvarna Ramachandran, G. Webb, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin

Physics and Astronomy Faculty Publications

We present results of analyses of two-pion interferometry in Au+Au collisions at √^S_NN=7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the BNL Relativistic Heavy Ion Collider Beam Energy Scan program. The extracted correlation lengths (Hanbury-Brown–Twiss radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (m_T) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive …

The Spitzer Survey Of Stellar Structure In Galaxies (S4g): Stellar Masses, Sizes, And Radial Profiles For 2352 Nearby Galaxies, Juan Carlos Muñoz-Mateos, Kartik Sheth, Michael Regan, Trisha Mizusawa

Aerospace, Physics, and Space Science Faculty Publications

The Spitzer Survey of Stellar Structure in Galaxies is a volume, magnitude, and size-limited survey of 2352 nearby galaxies with deep imaging at 3.6 and 4.5 μm. In this paper, we describe our surface photometry pipeline and showcase the associated data products that we have released to the community. We also identify the physical mechanisms leading to different levels of central stellar mass concentration for galaxies with the same total stellar mass. Finally, we derive the local stellar mass–size relation at 3.6 μm for galaxies of different morphologies. Our radial profiles reach stellar mass surface densities below ~1 M pc-2 …

Double Spin Asymmetries Of Inclusive Hadron Electroproduction From A Transversely Polarized 3He Target, C. Dutta, A. Kolarkar, Wolfgang Korsch, Y. X. Zhao, K. Allada, K. Aniol, J. R. M. Annand, T. Averett, F. Benmokhtar, W. Bertozzi, P. C. Bradshaw, P. Bosted, A. Camsonne

Physics and Astronomy Faculty Publications

We report the measurement of beam-target double spin asymmetries (A_LT) in the inclusive production of identified hadrons, e⃗ + ³He^↑→h+X, using a longitudinally polarized 5.9-GeV electron beam and a transversely polarized ³He target. Hadrons (π^±,K^±, and proton) were detected at 16^∘ with an average momentum ⟨P_h⟩=2.35 GeV/c and a transverse momentum (p_T) coverage from 0.60 to 0.68 GeV/c. Asymmetries from the ³He target were observed to be nonzero for π^± production when the target …

Evolution Of Magnetism In Single-Crystal Ca2Ru1−XIrXO4(0≤X≤0.65), Shujuan Yuan, Jsaminka Terzic, J. C. Wang, L. Li, Saicharan Aswartham, W. H. Song, F. Ye, Gang Cao

Physics and Astronomy Faculty Publications

We report structural, magnetic, transport, and thermal properties of single-crystal Ca₂Ru_1−xIr_xO₄(0≤x≤0.65). Ca₂RuO₄ is a structurally driven Mott insulator with a metal-insulator transition at T_MI=357K, which is well separated from antiferromagnetic order at T_N=110K. Substitution of a 5_d element, Ir, for Ru enhances spin-orbit coupling and locking between the structural distortions and magnetic moment canting. Ir doping intensifies the distortion or rotation of Ru/IrO₆ octahedra and induces weak ferromagnetic behavior along the c axis. In particular, Ir doping suppresses T_N but …

Moments Of The Neutron G2 Structure Function At Intermediate Q2, Wolfgang Korsch, P. Solvignon, N. Liyanage, J.-P. Chen, Seonho Choi, K. Slifer, K. Aniol, T. Averett, W. Boeglin, A. Camsonne, G. D. Cates

Physics and Astronomy Faculty Publications

We present new experimental results for the ³He spin structure function g₂ in the resonance region at Q² values between 1.2 and 3.0(GeV/c)². Spin dependent moments of the neutron were extracted. Our main result, the inelastic contribution to the neutron d₂ matrix element, was found to be small at ⟨Q²⟩=2.4(GeV/c)² and in agreement with the lattice QCD calculation. The Burkhardt-Cottingham sum rule for ³He and the neutron was tested with the measured data and using the Wandzura-Wilczek relation for the low x unmeasured region.

Hard Three-Loop Corrections To Hyperfine Splitting In Positronium And Muonium, Michael I. Eides, Valery A. Shelyuto

Physics and Astronomy Faculty Publications

We consider hard three-loop corrections to hyperfine splitting in muonium and positronium generated by the diagrams with closed electron loops. There are six gauge-invariant sets of such diagrams that generate corrections of order mα⁷. The contributions of these diagrams are calculated for an arbitrary electron-muon mass ratio without expansion in the small mass ratio. We obtain the formulas for contributions to hyperfine splitting that in the case of a small mass ratio describe corrections for muonium and in the case of equal masses describe corrections for positronium. The first few terms of the expansion of hard corrections in …

A Sensitive Faraday Rotation Setup Using Triple Modulation, G. Phelps, Josh Abney, Mark Broering, Wolfgang Korsch

Physics and Astronomy Faculty Publications

The utilization of polarized targets in scattering experiments has become a common practice in many major accelerator laboratories. Noble gases are especially suitable for such applications, since they can be easily hyper-polarized using spin exchange or metastable pumping techniques. Polarized helium-3 is a very popular target because it often serves as an effective polarized neutron due to its simple nuclear structure. A favorite cell material to generate and store polarized helium-3 is GE-180, a relatively dense aluminosilicate glass. In this paper, we present a Faraday rotation method, using a new triple modulation technique, where the measurement of the Verdet constants …

Observing Strategy For The Sdss-Iv/Manga Ifu Galaxy Survey, David R. Law, Renbin Yan, Matthew A. Bershady, Kevin Bundy, Brian Cherinka, Niv Drory, Nicholas Macdonald, José R. Sánchez-Gallego, David R. Wake, Anne-Marie Weijmans, Michael R. Blanton, Mark A. Klaene, Sean M. Moran, Sebastian F. Sanchez, Kai Zhang

Physics and Astronomy Faculty Publications

Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) is an integral-field spectroscopic survey that is one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV). MaNGA's 17 pluggable optical fiber-bundle integral field units (IFUs) will observe a sample of 10,000 nearby galaxies distributed throughout the SDSS imaging footprint (focusing particularly on the North Galactic Cap). In each pointing these IFUs are deployed across a 3° field; they yield spectral coverage 3600−10300 Å at a typical resolution R ~ 2000, and sample the sky with 2'' diameter fiber apertures with a total bundle fill factor of 56%. Observing …