Astrophysics and Astronomy Commons^™

Study Of Emic Wave Excitation Using Direct Ion Measurements, Kyungguk Min, Kaijun Liu, J. Bonnell, Aaron W. Breneman, Richard E. Denton, H. O. Funsten, Joerg-Micha Jahn, C A. Kletzing, W. S. Kurth, B. A. Larsen, Geoffrey Reeves, Harlan E. Spence, J. R. Wygant

Physics & Astronomy

With data from Van Allen Probes, we investigate electromagnetic ion cyclotron (EMIC) wave excitation using simultaneously observed ion distributions. Strong He band waves occurred while the spacecraft was moving through an enhanced density region. We extract from helium, oxygen, proton, and electron mass spectrometer measurement the velocity distributions of warm heavy ions as well as anisotropic energetic protons that drive wave growth through the ion cyclotron instability. Fitting the measured ion fluxes to multiple sinm-type distribution functions, we find that the observed ions make up about 15% of the total ions, but about 85% of them are still missing. By …

A Classical Morphological Analysis Of Galaxies In The Spitzer Survey Of Stellar Structure In Galaxies (S4g)., Ronald J. Buta, Kartik Sheth, E. Athanassoula, Albert Bosma, Johan H. Knapen, Eija Laurikainen, Heikki Salo, Debra M. Elmegreen, Luis C. Ho, Dennis Zaritsky, Helene M. Courtois, Joannah Hinz, Juan Carlos Muñoz-Mateos, Taehyun Kim, Michael Regan, Dimitri A. Gadotti, Armando Gil De Paz, Jarkko Laine, Karin Menendez-Delmestre, Sebastien Comeron, Santiago Erroz-Ferrer, Mark Seibert, Trisha Mizusawa, Benne W. Holwerda, Barry Madore

Faculty and Staff Scholarship

The Spitzer Survey of Stellar Structure in Galaxies (S4 G) is the largest available database of deep, homogeneous middle-infrared (mid-IR) images of galaxies of all types. The survey, which includes 2352 nearby galaxies, reveals galaxy morphology only minimally affected by interstellar extinction. This paper presents an atlas and classifications of S4 G galaxies in the Comprehensive de Vaucouleurs revised Hubble-Sandage (CVRHS) system. The CVRHS system follows the precepts of classical de Vaucouleurs morphology, modified to include recognition of other features such as inner, outer, and nuclear lenses, nuclear rings, bars, and disks, spheroidal galaxies, X patterns and box/peanut structures, OLR …

Geometrical Phases On The Poincaré And Bloch Spheres, Jason D. Mueller

Honors Capstones

No abstract provided.

Core-Collapse Supernovae Overview With Swift Collaboration, Kiranjyot Gill, Michele Zanolin, Marek Szczepańczyk

Publications

The Core-Collapse supernovae (CCSNe) mark the dynamic and explosive end of the lives of massive stars. The mysterious mechanism, primarily focused with the shock revival phase, behind CCSNe explosions could be explained by detecting the corresponding gravitational wave (GW) emissions by the laser interferometer gravitational wave observatory, LIGO. GWs are extremely hard to detect because they are weak signals in a floor of instrument noise. Optical observations of CCSNe are already used in coincidence with LIGO data, as a hint of the times where to search for the emission of GWs. More of these hints would be very helpful. For …

Elastic Waves Along A Fracture Intersection, Bradley C. Abell

Open Access Dissertations

Fractures and fracture networks play a significant role in the subsurface hydraulic connectivity within the Earth. While a significant amount of research has been performed on the seismic response of single fractures and sets of fractures, few studies have examined the effect of fracture intersections on elastic wave propagation. Intersections play a key role in the connectivity of a fracture network that ultimately affects the hydraulic integrity of a rock mass. In this dissertation two new types of coupled waves are examined that propagate along intersections. 1) A coupled wedge wave that propagates along a surface fracture with particle motion …

Meson Mass Decomposition From Lattice Qcd, Yi-Bo Yang, Ying Chen, Terrence Draper, Ming Gong, Keh-Fei Liu, Zhaofeng Liu, Jian-Ping Ma

Physics and Astronomy Faculty Publications

Hadron masses can be decomposed as a sum of quark and glue components that are defined through hadronic matrix elements of QCD operators. The components consist of the quark mass term, the quark energy term, the glue energy term, and the trace anomaly term. We calculate these components for mesons with lattice QCD for the first time. The calculation is carried out with overlap fermion on 2+1 flavor domain-wall fermion gauge configurations. We confirm that ~50% of the light pion mass comes from the quark mass term and ~10% comes from the quark energy; whereas, for the ρ meson, the …

A Classical Morphological Analysis Of Galaxies In The Spitzer Survey Of Stellar Structure In Galaxies (S4g), Ronald J. Buta, Trisha Mizusawa

Aerospace, Physics, and Space Science Faculty Publications

The Spitzer Survey of Stellar Structure in Galaxies (S4G) is the largest available database of deep, homogeneous middle-infrared (mid-IR) images of galaxies of all types. The survey, which includes 2352 nearby galaxies, reveals galaxy morphology only minimally affected by interstellar extinction. This paper presents an atlas and classifications of S4G galaxies in the Comprehensive de Vaucouleurs revised Hubble-Sandage (CVRHS) system. The CVRHS system follows the precepts of classical de Vaucouleurs morphology, modified to include recognition of other features such as inner, outer, and nuclear lenses, nuclear rings, bars, and disks, spheroidal galaxies, X patterns and box/peanut structures, OLR subclass outer …

Uv Luminosity Functions At Redshifts Z~4 To Z~10 : 10,000 Galaxies From Hst Legacy Fields., R. J. Bouwens, G. D. Illingworth, P. A. Oesch, M. Trenti, I. Labbe, L. Bradley, C. M. Carollo, P. G. Van Dokkum, V. Gonzalez, Benne W. Holwerda, M. Franx, L. Spitler, R. Smit, D. Magee

Faculty and Staff Scholarship

The remarkable Hubble Space Telescope (HST) data sets from the CANDELS, HUDF09, HUDF12, ERS, and BoRG/HIPPIES programs have allowed us to map the evolution of the rest-frame UV luminosity function (LF) from z ~ 10 to z ~ 4. We develop new color criteria that more optimally utilize the full wavelength coverage from the optical, near-IR, and mid-IR observations over our search fields, while simultaneously minimizing the incompleteness and eliminating redshift gaps. We have identified 5859, 3001, 857, 481, 217, and 6 galaxy candidates at z ~ 4, z ~ 5, z ~ 6, z ~ 7, z ~ 8, …

Vegas-Sss. A Vst Early-Type Galaxy Survey: Analysis Of Small Stellar Systems: Testing The Methodology On The Globular Cluster System In Ngc 3115⋆, Michele Cantiello, Massimo Capaccioli, Nicola Napolitano, Aniello Grado, Luca Limatola, Maurizio Paolillo, Enrica Iodice, Aaron Romanowsky, Duncan Forbes, Gabriella Raimondo, Marilena Spavone, Francesco La Barbera, Thomas Puzia, Pietro Schipani

Faculty Publications

We present a study of globular clusters (GCs) and other small stellar systems (SSSs) in the field of NGC 3115, observed as part of the ongoing wide-field imaging survey VEGAS, carried out with the 2.6 m VST telescope. We used deep g and i observations of NGC 3115, a well-studied lenticular galaxy that is covered excellently well in the scientific literature. This is fundamental to test the methodologies, verify the results, and probe the capabilities of the VEGAS-SSS. Leveraging the large field of view of the VST allowed us to accurately study the distribution and properties of SSSs as a …

A Statistical Study Into The Spatial Distribution And Dawn-Dusk Asymmetry Of Dayside Magnetosheath Ion Temperatures As A Function Of Upstream Solar Wind Conditions, A. P. Dimmock, K. Nykyri, H. Karimabadi, A. Osmane, T. I. Pulkkinen

Publications

The magnetosheath contains the shocked solar wind and behaves as a natural filter to the solar wind plasma before it reaches the magnetosphere. The redistribution of kinetic energy at the bow shock results in significant thermalization of the solar wind plasma, resulting in a magnetosheath temperature profile which is highly nonhomogeneous and nonisotropic and differs between the dawn and dusk flanks. The present study attempts to study the spatial distribution of magnetosheath ion temperature as a function of upstream solar wind conditions. We pay particular attention to the dawn/dusk asymmetry in which we attempt to quantify using experimental data collected …

Ultracool White Dwarfs And The Age Of The Galactic Disc, A. Gianninas, B. Curd, John R. Thorstensen, Mukremin Kilic

Dartmouth Scholarship

We present parallax observations and a detailed model atmosphere analysis of 54 cool and ultracool (Teff < 4000 K) white dwarfs (WDs) in the solar neighbourhood. For the first time, a large number of cool and ultracool WDs have distance and tangential velocities measurements available. Our targets have distances ranging from 21 pc to >100 pc, and include five stars within 30 pc. Contrary to expectations, all but two of them have tangential velocities smaller than 150 km s−1 thus suggesting Galactic disc membership. The oldest WDs in this sample have WD cooling ages of 10 Gyr, providing a firm lower limit to the age of the thick disc population. Many of our targets have uncharacteristically large radii, indicating that they are low mass WDs. It appears that we have detected the brighter population of cool and ultracool …

A Study Of Thunderstorm Microphysical Properties And Lightning Flash Counts Associated With Terrestrial Gamma-Ray Flashes, D. E. Barnes, M. E. Splitt, J. R. Dwyer, S. Lazarus, D. M. Smith, H. K. Rassoul

Aerospace, Physics, and Space Science Faculty Publications

The terrestrial gamma ray flash (TGF) is an emission of highly energetic radiation produced by or at least in close association with lightning. Previous investigations attempted to isolate the production mechanisms and production altitude(s) of TGFs as well as macrophysical characteristics, while thunderstorm microphysical characteristics were largely ignored. This investigation into thunderstorms and their hydrometeor and flash characteristics utilize temporal and spatial coincident satellite passes between the Reuven Ramaty High Energy Solar Spectroscopic Imager and the Tropical Rainfall Measuring Mission to determine the bulk (or footprint) microphysical properties of two types of study events, the thunderstorm complexes which are associated …

Directed Search For Gravitational Waves From Scorpius X-1 With Initial Ligo Data, J. Aasi, B. P. Abbott, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soumya Mohanty, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

We present results of a search for continuously emitted gravitational radiation, directed at the brightest low-mass x-ray binary, Scorpius X-1. Our semicoherent analysis covers 10 days of LIGO S5 data ranging from 50-550 Hz, and performs an incoherent sum of coherent F-statistic power distributed amongst frequency-modulated orbital sidebands. All candidates not removed at the veto stage were found to be consistent with noise at a 1% false alarm rate. We present Bayesian 95% confidence upper limits on gravitational-wave strain amplitude using two different prior distributions: a standard one, with no a priori assumptions about the orientation of Scorpius X-1; and …

Supermassive Black Hole Scaling Relations, Ismaeel Abdulla Akhlite Al-Baidhany

Theses and Dissertations

In this dissertation, the determination of the masses of supermassive black holes (SMBHs) and the properties of their host spiral galaxies are focused for the purposes of constraining scaling relations and with the aim of understanding the role of SMBHs in the evolution of galaxies. The several techniques in this work as summarized are focused on in Chapter 2. Direct techniques (reverberation mapping, stellar and gas dynamics, maser modeling) and indirect techniques (the SMBH mass versus stellar/gas velocity dispersion relation and the SMBH mass versus spiral arm pitch angle relation) have been used to estimate SMBH masses. Then the measurement …

Determination Of Resonance Locations In Barred Spiral Galaxies, Amber Sierra

Theses and Dissertations

We applied a method identified by Puerari & Dottori (1997) to find the corotation radii of 57 galaxies. This entailed taking Fourier transforms along radial cuts in the u, g, r, i, and z wavebands and comparing the phase angles as a function of radius between them. The radius at which the phase angles cross indicates the location of the corotation radius. We then calculated the relative bar pattern speed, R and classified the bar as fast, less than 1.4, or slow, greater than or equal to 1.4. Finally, we found that our results were consistent with previously determined values …

The Riemann Curvature Tensor, Its Invariants, And Their Use In The Classification Of Spacetimes, Jesse Hicks

Presentations and Publications

The equivalence problem in general relativity is to determine whether two solutions of the Einstein field equations are isometric. Petrov has given a classification of metrics according to their isometry algebras. This talk discusses the use of the Petrov classification scheme, together with the use of scalar curvature invariants, to address the equivalence problem. These are the slides for a presentation at the Mathematics Association of America Spring 2015 conference at Brigham Young University.

A Connection Between Obscuration And Star Formation In Luminous Quasars, Chien-Ting J. Chen, Ryan C. Hickox, Stacey Alberts, Chris M. Harrison

Dartmouth Scholarship

We present a measurement of the star formation properties of a uniform sample of mid-IR selected, unobscured and obscured quasars (QSO1s and QSO2s) in the Bo\"otes survey region. We use an spectral energy distribution (SED) analysis for photometric data spanning optical to far-IR wavelengths to decompose AGN and host galaxy components. We find that when compared to a matched sample of QSO1s, the QSO2s have higher far-IR detection fractions, far-IR fluxes and infrared star formation luminosities (L^SF_IR) by a factor of ∼2. Correspondingly, we show that the AGN obscured fraction rises from 0.3 to 0.7 between 4−40×10 …

Protolunar Disk Evolution And The Depletion Of Volatile Elements In The Moon, Robin M. Canup, Channon Visscher, Julien Salmon, Bruce Fegley Jr.

Faculty Work Comprehensive List

We explore how the evolution of the protolunar disk could lead to a depletion in K, Na, and Zn in the Moon relative to Earth even in the absence of escape.

Weighing Galaxy Disks With The Baryonic Tully-Fisher Relation, Stacy S. Mcgaugh

Faculty Scholarship

We estimate the stellar masses of disk galaxies with two independent methods: a photometrically self-consistent color?mass-to-light ratio relation (CMLR) from population synthesis models, and the baryonic Tully?Fisher relation (BTFR) calibrated by gas-rich galaxies. These two methods give consistent results. The CMLR correctly converts distinct Tully?Fisher relations in different bands into the same BTFR. The BTFR is consistent with Mb ∝ Vf4 over nearly six decades in mass, with no hint of a change in slope over that range. The intrinsic scatter in the BTFR is negligible, implying that the IMF of disk galaxies is effectively universal. The gas-rich BTFR suggests …

Spectroscopic Needs For Imaging Dark Energy Experiments, Jeffrey A. Newman, Alexandra Abate, Filipe B. Abdalla, Sahar Allam, Steven W. Allen, Réza Ansari, Stephen Bailey, Wayne A. Barkhouse, Timothy C. Beers, Michael R. Blanton, Mark Brodwin, Joel R. Brownstein, Robert J. Brunner, Matias Carrasco Kind, Jorge L. Cervantes-Cota, Elliott Cheu, Nora Elisa Chisari, Matthew Colless, Johan Comparat, Jean Coupon, Carlos E. Cunha, Axel De La Macorra, Ian P. Dell'antonio, Brenda L. Frye, Eric J. Gawiser, Neil Gehrels, Kevin Grady, Alex Hagen, Patrick B. Hall, Andrew P. Hearin, Hendrik Hildebrandt, Christopher M. Hirata, Shirley Ho, Klaus Honscheid, Dragan Huterer, Željko Ivezić, Jean-Paul Kneib, Jeffrey W. Kruk, Ofer Lahav, Rachel Mandelbaum, Jennifer L. Marshall, Daniel J. Matthews, Brice Ménard, Ramon Miquel, Marc Moniez, H. W. Moos, John Moustakas, Adam D. Myers, Casey Popovich, John A. Peacock, Changbom Park, Mubdi Rahman, Jason Rhodes, Jean-Stephane Ricol, Iftach Sadeh, Anže Slozar, Samuel J. Schmidt, Daniel K. Stern, J. Anthony Tyson, Anja Von Der Linden, Risa H. Wechsler, W. M. Wood-Vasey, Andrew R. Zentner

Physics Faculty Publications

Ongoing and near-future imaging-based dark energy experiments are critically dependent upon photometric redshifts (a.k.a. photo-z’s): i.e., estimates of the redshifts of objects based only on flux information obtained through broad filters. Higher-quality, lower-scatter photo-z’s will result in smaller random errors on cosmological parameters; while systematic errors in photometric redshift estimates, if not constrained, may dominate all other uncertainties from these experiments. The desired optimization and calibration is dependent upon spectroscopic measurements for secure redshift information; this is the key application of galaxy spectroscopy for imaging-based dark energy experiments.

Hence, to achieve their full potential, imaging-based experiments …

Asymmetric Kelvin-Helmholtz Propagation At Saturn's Dayside Magnetopause, X. Ma, B. Stauffer, P. A. Delamere, A. Otto

Publications

At Saturn's magnetopause, the shear flows are maximized (minimized) in the prenoon (postnoon) sector due to the rapid planetary rotation and the corotating magnetodisc. As such, the prenoon sector is expected to be more Kelvin‐Helmholtz (KH) unstable than the postnoon sector; however, in situ Cassini data analyses showed that the evidence of KH activity favors the postnoon sector. In this study, we use a two‐dimensional MHD simulation to demonstrate that fast‐growing KH modes strongly deform and diffuse the boundary layer on a time scale of a few minutes in the prenoon sector. Therefore, the KH observational signature is difficult to …

Spitzer Space Telescope Measurements Of Dust Reverberation Lags In The Seyfert 1 Galaxy Ngc 6418, Billy Vazquez, Pasquale Galianni, Michael Richmond, Andrew Robinson, David J. Axon, Keith Horne, Triana Almeyda, Michael Fausnaugh, Bradley M. Peterson, Mark Bottorff, Jack Gallimore, Moshe Elitzur, Hagai Netzer, Thaisa Storchi-Bergmann, Alessandro Marconi, Alessandro Capetti, Dan Batcheldor, Catherine Buchanan, Giovanna Stirpe, Makoto Kishimoto, Christopher Packham, Enrique Perez, Clive Tadhunter, John Upton, Vincente Estrada-Carpenter

Physics and Astronomy Faculty Publications

We present results from a 15 month campaign of high-cadence (~3 days) mid-infrared Spitzer and optical (B and V) monitoring of the Seyfert 1 galaxy NGC 6418, with the objective of determining the characteristic size of the dusty torus in this active galactic nucleus (AGN). . . .

For the remainder of the abstract, please visit:

http://dx.doi.org/10.1088/0004-637X/801/2/127

Spectroscopic Orbital Periods For 29 Cataclysmic Variables From The Sloan Digital Sky Survey, John R. Thorstensen, Cynthia J. Taylor, Christopher S. Peters, Julie N. Skinner

Dartmouth Scholarship

We report follow-up spectroscopy of 29 cataclysmic variables from the Sloan Digital Sky Survey (SDSS), 22 of which were discovered by SDSS and seven of which are previously known systems that were recovered in SDSS. The periods for 16 of these objects were included in the tabulation by Gänsicke et al. While most of the systems have periods less than 2 hr, only one has a period in the 80–86 minutes "spike" found by Gänsicke et al., and 11 have periods longer than 3 hr, indicating that the present sample is skewed toward longer-period, higher-luminosity objects. Seven of the objects …

Spectroscopic Confirmation Of An Ultramassive And Compact Galaxy At Z = 3.35: A Detailed Look At An Early Progenitor Of Local Giant Ellipticals, Z. Cemile Marsan, Danilo Marchesini, Gabriel B. Brammer, Mauro Stefanon, Adam Muzzin, Alberto Fernández-Soto, Stefan Geier, Kevin N. Hainline

Dartmouth Scholarship

We present the first spectroscopic confirmation of an ultra-massive galaxy at redshift z>3 using data from Keck-NIRSPEC, VLT-Xshooter, and GTC-Osiris. We detect strong [OIII] and Lyα emission, and weak [OII], CIV, and HeII, placing C1-23152 at a spectroscopic redshift of zspec=3.351. The modeling of the emission-line corrected spectral energy distribution results in a best-fit stellar mass of M∗=3.1+0.6−0.7×1011M⊙, a star-formation rate of <7 M⊙yr−1, and negligible dust extinction. The stars appear to have formed in a short intense burst ~300-500 Myr prior to the observation epoch, setting the formation redshift of this galaxy at z~4.1. From the analysis of the line ratios and widths, and the observed flux at 24μm, we confirm the presence of a luminous hidden active galactic nucleus (AGN), with bolometric luminosity of ~1046ergs−1. Potential contamination to the observed SED from the AGN continuum is constrained, placing a lower limit on the stellar mass of 2×1011M⊙. HST/WFC3 H160 and ACS I814 images are modeled, resulting in an effective radius of re~1 kpc in the H160 band and a Sersic index n~4.4. This object may be a prototype of the progenitors of local most massive elliptical galaxies in the first 2 Gyr of cosmic history, having formed most of its stars at z>4 in a highly dissipative, intense, and short burst of star formation. C1-23152 is completing its transition to a post-starburst phase while hosting a powerful AGN, potentially responsible for the quenching of the star formation activity.

Stellar Masses From The Candels Survey: The Goods-South And Uds Fields, P. Santini, H. C. Ferguson, A. Fontana, B. Mobasher, G. Barro, M. Castellano, S. L. Finkelstein, A. Grazian, L. T. Hsu, B. Lee, S.-K. Lee, J. Pforr, M. Salvato, T. Wiklind, S. Wuyts, O. Almaini, M. C. Cooper, A. Galametz, B. Weiner, R. Amorin, K. Boutsia, C. J. Conselice, T. Dahlen, M. E. Dickinson, M. Giavalisco, N. A. Grogin, Y. Guo, N. P. Hathi, Dale D. Kocevski, A. M. Koekemoer, P. Kurczynski, E. Merlin, A. Mortlock, J. A. Newman, D. Paris, L. Pentericci, R. Simons, S. P. Willner

Physics and Astronomy Faculty Publications

We present the public release of the stellar mass catalogs for the GOODS-S and UDS fields obtained using some of the deepest near-IR images available, achieved as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey project. We combine the effort from 10 different teams, who computed the stellar masses using the same photometry and the same redshifts. Each team adopted their preferred fitting code, assumptions, priors, and parameter grid. The combination of results using the same underlying stellar isochrones reduces the systematics associated with the fitting code and other choices. Thanks to the availability of different estimates, we …

Spitzer Space Telescope Measurements Of Dust Reverberation Lags In The Seyfert 1 Galaxy Ngc 6418, Billy Vazquez, Dan Batcheldor

Aerospace, Physics, and Space Science Faculty Publications

We present results from a 15 month campaign of high-cadence (∼3 days) mid-infrared Spitzer and optical (B and V) monitoring of the Seyfert 1 galaxy NGC 6418, with the objective of determining the characteristic size of the dusty torus in this active galactic nucleus (AGN). We find that the 3.6 and 4.5 μm flux variations lag behind those of the optical continuum by 37.2 ^+2.4 _-2.2 days and -47.1 ^+3.1 _-3.1 days, respectively. We report a cross-correlation time lag between the 4.5 and 3.6 μm flux of 13.9 ^+0.5 _-0.1 days. The lags indicate that the dust emitting at 3.6 …

Structural Distortion-Induced Magnetoelastic Locking In Sr2Iro4 Revealed Through Nonlinear Optical Harmonic Generation, D. H. Torchinsky, H. Chu, L. Zhao, N. B. Perkins, Y. Sizyuk, T. Qi, Gang Cao, D. Hsieh

Physics and Astronomy Faculty Publications

We report a global structural distortion in Sr₂IrO₄ using spatially resolved optical second and third harmonic generation rotational anisotropy measurements. A symmetry lowering from an I4₁/acd to I4₁/a space group is observed both above and below the Néel temperature that arises from a staggered tetragonal distortion of the oxygen octahedra. By studying an effective superexchange Hamiltonian that accounts for this lowered symmetry, we find that perfect locking between the octahedral rotation and magnetic moment canting angles can persist even in the presence of large noncubic local distortions. Our results …

Stellar Activity And Its Implications For Exoplanet Detection On Gj 176, Paul Robertson, Michael Endl, Gregory W. Henry, William D. Cochran, Phillip J. Macqueen, Michael H. Williamson

Information Systems and Engineering Management Research Publications

We present an in-depth analysis of stellar activity and its effects on radial velocity (RV) for the M2 dwarf GJ 176 based on spectra taken over 10 yr from the High Resolution Spectrograph on the Hobby–Eberly Telescope. These data are supplemented with spectra from previous observations with the HIRES and HARPS spectrographs, and V- and R-band photometry taken over six years at the Dyer and Fairborn observatories. Previous studies of GJ 176 revealed a super-Earth exoplanet in an 8.8-day orbit. However, the velocities of this star are also known to be contaminated by activity, particularly at the 39-day stellar rotation …

Magnetic Response Of Aperiodic Wire Networks Based On Fibonacci Distortions Of Square Antidot Lattices, Barry Farmer, Vinayak Bhat, J. Sklenar, Eric Teipel, Justin Woods, J. B. Ketterson, J. Todd Hastings, Lance Delong

Physics and Astronomy Faculty Publications

The static and dynamic magnetic responses of patterned ferromagnetic thin films are uniquely altered in the case of aperiodic patterns that retain long-range order (e.g., quasicrystals). We have fabricated permalloy wire networks based on periodic square antidot lattices (ADLs) distorted according to an aperiodic Fibonacci sequence applied to two lattice translations, d₁  = 1618 nm and d₂  = 1000 nm. The wire segment thickness is fixed at t = 25 nm, and the width W varies from 80 to 510 nm. We measured the DC magnetization between room temperature and 5 K. Room-temperature, narrow-band (9.7 GHz) ferromagnetic resonance …

Room Temperature Optical Anisotropy Of A Lamno3 Thin-Film Induced By Ultra-Short Pulse Laser, Purevdorj Munkhbaatar, Zsolt Marton, Baatarchuluun Tsermaa, Woo Seok Choi, Sung S. Ambrose Seo, Jin Seung Kim, Naoyuki Nakagawa, Harold Y. Hwang, Ho Nyung Lee, Kim Myung-Whun

Physics and Astronomy Faculty Publications

We observed ultra-short laser pulse-induced transient optical anisotropy in a LaMnO₃ thin film. The anisotropy was induced by laser pulse irradiation with a fluence of less than 0.1 mJ/cm² at room temperature. The transmittance and reflectance showed strong dependence on the polarization states of the pulses. For parallel and perpendicular polarization states, there exists a difference of approximately 0.2% for transmittance and 0.05% for reflectance at 0.3 ps after the irradiation with a pump pulse, respectively. The theoretical values for optical transmittance and reflectance with an assumption of an orbital ordering of 3d e_g electrons in …