Results for "Kate H. R. Rubin"

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Gas Accretion Traced in Absorption in Galaxy SpectroscopyDec 02 2016The positive velocity shift of absorption transitions tracing diffuse material observed in a galaxy spectrum is an unambiguous signature of gas flow toward the host system. Spectroscopy probing, e.g., NaI D resonance lines in the rest-frame optical or ... More
Simulating the Carbon Footprint of Galactic HalosDec 07 2015Jul 27 2016We compare simulations, including the Illustris simulations, to observations of CIV and CII absorption at z=2-4. These are the CIV column density distribution function in the column density range $10^{12} - 10^{15}$ cm$^{-2}$, the CIV equivalent width ... More
The White Dwarf Population in NGC 1039 (M34) and the White Dwarf Initial-Final Mass RelationMay 20 2008We present the first detailed photometric and spectroscopic study of the white dwarfs (WDs) in the field of the ~225 Myr old (log tau_cl = 8.35) open cluster NGC 1039 (M34) as part of the ongoing Lick-Arizona White Dwarf Survey. Using wide-field UBV imaging, ... More
On the OVI Abundance in the Circumgalactic Medium of Low-Redshift GalaxiesNov 02 2015We analyze the mass, temperature, metal enrichment, and OVI abundance of the circumgalactic medium (CGM) around $z\sim 0.2$ galaxies of mass $10^9 M_\odot <M_\bigstar < 10^{11.5} M_\odot$ in the Illustris simulation. Among star-forming galaxies, the mass, ... More
Galaxies probing galaxies: cool halo gas from a z = 0.47 post-starburst galaxyJul 01 2009We study the cool gas around a galaxy at z = 0.4729 using Keck/LRIS spectroscopy of a bright (B = 21.7) background galaxy at z = 0.6942 at a transverse distance of 16.5/h_70 kpc. The background galaxy spectrum reveals strong FeII, MgII, MgI, and CaII ... More
On the Cosmic Evolution of Fe/Mg in QSO Absorption Line SystemsMar 23 2015Jun 10 2015We investigate the variation of the ratio of the equivalent widths of the FeII$\lambda$2600 line to the MgII$\lambda\lambda$2796,2803 doublet as a function of redshift in a large sample of absorption lines drawn from the JHU-SDSS Absorption Line Catalog. ... More
The Direct Detection of Cool, Metal-Enriched Gas Accretion onto Galaxies at z ~ 0.5Oct 04 2011We report on the discovery of cool gas inflow toward six star-forming galaxies with redshifts z ~ 0.35 - 1. Analysis of MgII and FeII resonance-line absorption in Keck/LRIS spectroscopy of this sample reveals velocity shifts of 80 - 200 km/s and equivalent ... More
A VLT/FORS2 Narrowband Imaging Search for MgII Emission Around z ~ 0.7 GalaxiesMay 14 2019We perform a Very Large Telescope FOcal Reducer and low dispersion Spectrograph 2 (VLT/FORS2) narrowband imaging search around 5 star-forming galaxies at redshift z=0.67-0.69 in the Great Observatories Origins Deep Survey South (GOODS-S) field to constrain ... More
Galaxies Probing Galaxies in PRIMUS - II. The Coherence Scale of the Cool Circumgalactic MediumJun 22 2018Sep 21 2018The circumgalactic medium (CGM) close to ~L* star-forming galaxies hosts strong MgII 2796 absorption (with equivalent width W_2796>0.1 Ang) with a near-unity covering fraction. To characterize the spatial coherence of this absorption, we analyze the W_2796 ... More
Far-UV HST Spectroscopy of An Unusual Hydrogen Poor Superluminous Supernova: SN2017egmNov 05 2017Apr 17 2018SN2017egm is the closest (z=0.03) H-poor superluminous supernova (SLSN-I) detected to date, and a rare example of an SLSN-I in a massive and metal-rich galaxy. Here we present the HST UV & optical spectra covering (1000 - 5500)A taken at +3 day relative ... More
Galaxies Probing Galaxies in PRIMUS - I. Sample, Spectroscopy, and Characteristics of the z~0.5 MgII-Absorbing Circumgalactic MediumNov 23 2017Spectroscopy of background QSO sightlines passing close to foreground galaxies is a potent technique for studying the circumgalactic medium (CGM). QSOs are effectively point sources, however, limiting their potential to constrain the size of circumgalactic ... More
Ensemble Properties of the White Dwarf Population of the Old, Solar Metallicity Open Star Cluster Messier 67Jul 24 2018White dwarfs are excellent forensic tools for studying end-of-life issues surrounding low- and intermediate-mass stars, and the old, solar-metallicity open star cluster Messier 67 is a proven laboratory for the study of stellar evolution for solar-type ... More
Low-ionization Line Emission from Starburst Galaxies: A New Probe of Galactic-Scale OutflowsAug 19 2010We study the kinematically narrow, low-ionization line emission from a bright, starburst galaxy at z = 0.69 using slit spectroscopy obtained with Keck/LRIS. The spectrum reveals strong absorption in MgII and FeII resonance transitions with Doppler shifts ... More
Evidence for Ubiquitous Collimated Galactic-Scale Outflows along the Star-Forming Sequence at z~0.5Jul 04 2013We present an analysis of the MgII 2796, 2803 and FeII 2586, 2600 absorption line profiles in individual spectra of 105 galaxies at 0.3<z<1.4. The galaxies, drawn from redshift surveys of the GOODS fields and the Extended Groth Strip, fully sample the ... More
Dissecting the Gaseous Halos of z~2 Damped Ly$α$ Systems with Close Quasar PairsNov 21 2014We use spectroscopy of close pairs of quasars to study diffuse gas in the circumgalactic medium (CGM) surrounding a sample of 40 Damped Lya systems (DLAs). The primary sightline in each quasar pair probes an intervening DLA in the redshift range 1.6 < ... More
Time-resolved Spectroscopy of the Polar EU Cancri in the Open Cluster Messier 67Jan 25 2013We present time-resolved spectroscopic and polarimetric observations of the AM Her system EU Cnc. EU Cnc is located near the core of the old open cluster Messier 67; new proper motion measurements indicate that EU Cnc is indeed a member of the star cluster, ... More
Flux ratio [Ne V] 14.3/24.3 as a test of collision strengthsFeb 18 2004From ISO [Ne V] 14.3/24.3 micron line flux ratios, we find that 10 out of 20 planetary nebulae (PNs) have measured ratios below the low-electron density (N_e) theoretical predicted limit. Such astronomical data serve to provide important tests of atomic ... More
The Persistence of Cool Galactic Winds in High Stellar Mass Galaxies Between z~1.4 and ~1Dec 13 2009We present an analysis of the MgII 2796, 2803 and FeII 2586, 2600 absorption line profiles in coadded spectra of 468 galaxies at 0.7 < z < 1.5. The galaxy sample, drawn from the Team Keck Treasury Redshift Survey of the GOODS-N field, has a range in stellar ... More
Chandra Constraints on the AGN Fraction and Star Formation Rate of Red z>~2 Galaxies in the FIRES MS1054-03 FieldAug 04 2004Aug 13 2004Very deep near-infrared observations have recently uncovered a significant population of red galaxies at redshifts z>2. These distant red galaxies (DRGs) are efficiently selected by the criterion J-K>2.3. We use Chandra data to examine the X-ray emission ... More
The Nature of Ionized Gas in the Milky Way Galactic FountainApr 24 2019We address the spatial scale, ionization structure and metal content of gas at the Milky Way disk-halo interface detected as absorption in the foreground of seven halo blue horizontal branch stars (BHBs). The closely-spaced, high-latitude BHB sightlines ... More
The ionization equilibrium of iron in H II regionsDec 09 2003We study the ionization equilibrium of Fe using photoionization models that incorporate improved values for the ionization and recombination cross-sections and the charge-exchange rates for the Fe ions. The previously available photoionization models ... More
Quasars probing quasars X: The quasar pair spectral databaseApr 23 2018The rare close projection of two quasars on the sky provides the opportunity to study the host galaxy environment of a foreground quasar in absorption against the continuum emission of a background quasar. For over a decade the "Quasars probing quasars" ... More
Simple Models of Metal-Line Absorption and Emission from Cool Gas OutflowsFeb 16 2011We analyze the absorption and emission-line profiles produced by a set of simple, cool gas wind models motivated by galactic-scale outflow observations. We implement monte carlo radiative transfer techniques that track the propagation of scattered and ... More
Quasars Probing Quasars VI. Excess HI Absorption Within One Proper Mpc of z~2 QuasarsAug 28 2013With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We use a sample of 650 projected quasar pairs to study the HI Lya absorption transverse to luminous, ... More
Andromeda's Parachute: A Bright Quadruply Lensed Quasar at z=2.377Jul 18 2017Jul 31 2017We present Keck Cosmic Web Imager spectroscopy of the four putative images of the lensed quasar candidate J014709+463037 recently discovered by Berghea et al. (2017). The data verify the source as a quadruply lensed, broad absorption-line quasar having ... More
Helium Recombination Lines as a Probe of Abundance and Temperature ProblemsJun 14 2005The paper presents a simplified formula to determine an electron temperature, Te(He I), for planetary nebulae (PNe) using the He I 7281/6678 line flux ratio. In our previous studies of Te(He I) (Zhang et al. 2005), we used the He I line emission coefficients ... More
Helium recombination spectra as temperature diagnostics for planetary nebulaeJan 10 2005Electron temperatures derived from the \ion{He}{1} recombination line ratios, designated $T_{\rm e}$(\ion{He}{1}), are presented for 48 planetary nebulae (PNe). We study the effect that temperature fluctuations inside nebulae have on the $T_{\rm e}$(\ion{He}{1}) ... More
Zooming in on accretion - II. Cold Circumgalactic Gas Simulated with a super-Lagrangian Refinement SchemeNov 05 2018In this study we explore the complex multi-phase gas of the circumgalactic medium (CGM) surrounding galaxies. We propose and implement a novel, super-Lagrangian 'CGM zoom' scheme in the moving-mesh code AREPO, which focuses more resolution into the CGM ... More
Multiconfiguration Dirac-Hartree-Fock energy levels and transition probabilities for 3d^5 in Fe IVSep 29 2008Multiconfiguration Dirac-Hartree-Fock electric quadrupole (E2) and magnetic dipole (M1) transition probabilities are reported for transitions between levels of 3d^5 in [Fe IV]. The accuracy of the ab initio energy levels and the agreement in the length ... More
Comment on Ghost imaging with a single detector [arXiv0812.2633v2]Feb 11 2009Computational ghost imaging has been demonstrated experimentally recently. In this comment we wish to clarify the difference between pseudothermal ghost imaging (PGI) and computational ghost imaging (CGI). In particular, to emphasize the physics that ... More
Comment on a paper by Lapaire and SipeAug 08 2006In a recent paper [quant-ph/0607008] Lapaire and Sipe argue that one can discuss interference experiments using entangled photons in terms of single photon wave functions. Furthermore, they argue that contrary to the claim of the authors of the postponed ... More
Entanglement and State PreparationJan 26 1999Jan 27 1999When a subset of particles in an entangled state is measured, the state of the subset of unmeasured particles is determined by the outcome of the measurement. This first measurement may be thought of as a state preparation for the remaining particles. ... More
Simulating entangled sources by classically correlated sources and quantum imagingMar 31 2003Jul 29 2003We discuss the problem of when a set of measurements made on an entangled source can be simulated with a classically correlated source. This is discussed in general and some examples are given. The question of which aspects of quantum imaging can be simulated ... More
SDSS-IV MaNGA: A serendipitous observation of a potential gas accretion eventSep 07 2016The nature of warm, ionized gas outside of galaxies may illuminate several key galaxy evolutionary processes. A serendipitous observation by the MaNGA survey has revealed a large, asymmetric H$\alpha$ complex with no optical counterpart that extends $\approx8"$ ... More
SDSS-IV MaNGA: A serendipitous observation of a potential gas accretion eventSep 07 2016Oct 03 2016The nature of warm, ionized gas outside of galaxies may illuminate several key galaxy evolutionary processes. A serendipitous observation by the MaNGA survey has revealed a large, asymmetric H$\alpha$ complex with no optical counterpart that extends $\approx8"$ ... More
$^{12}$C/$^{13}$C ratio in planetary nebulae from the IUE archivesJan 06 2004We investigated the abundance ratio of $^{12}$C/$^{13}$C in planetary nebulae by examining emission lines arising from \ion{C}{3} $2s2p ^3P_{2,1,0} \to 2s^2 ^1S_0$. Spectra were retrieved from the International Ultraviolet Explorer archives, and multiple ... More
Cloud fragmentation and proplyd-like features in HII regions imaged by HSTFeb 24 2006We have analyzed HST ACS and WFPC2 new and archival images of eight HII regions to look for new proto-planetary disks (proplyds) similar to those found in the Orion Nebula. We find a wealth of features similar in size (though many are larger) to the bright ... More
Probability Density of the Multipole Vectors for a Gaussian Cosmic Microwave BackgroundApr 27 2007Aug 09 2007We review Maxwell's multipole vectors, and elucidate some of their mathematical properties, with emphasis on the application of this tool to the cosmic microwave background (CMB). In particular, for a completely random function on the sphere (corresponding ... More
Three-dimensional chemically homogeneous and bi-abundance photoionization models of the "super-metal-rich" planetary nebula NGC 6153Sep 30 2010Deep spectroscopy of the planetary nebula (PN) NGC\,6153 shows that its heavy element abundances derived from optical recombination lines (ORLs) are ten times higher than those derived from collisionally excited lines (CELs), and points to the existence ... More
Ghost Interference with Optical Parametric AmplifierJul 21 2004The 'Ghost' interference experiment is analyzed when the source of entangled photons is a multimode Optical Parametric Amplifier(OPA) whose weak limit is the two-photon Spontaneous Parametric Downconversion(SPDC) beam. The visibility of the double-slit ... More
Pionic Bound States in Momentum SpaceAug 06 1993Bound states of the pion--nucleus system are investigated in momentum space using a microscopic optical potential with inherent energy dependences and nonlocalities arising from elementary potential models. The wave equation and computational techniques ... More
On the Measurement of Elemental Abundance Ratios in Inner Galaxy H II RegionsApr 20 2004Although variations in elemental abundance ratios in the Milky Way Galaxy certainly exist, details remain uncertain, particularly in the inner Galaxy, where stars and H II regions in the Galactic plane are obscured optically. In this paper we revisit ... More
Glomerular protein separation as a mechanism for powering renal concentrating processesMay 22 2014Various models have been proposed to explain the urine concentrating mechanism in mammals, however uncertainty remains regarding the origin of the energy required for the production of concentrated urine. We propose a novel mechanism for concentrating ... More
The [Fe IV] Discrepancy: Constraining the Iron Abundances in NebulaeApr 05 2005Apr 18 2005We study the current discrepancy between the model-predicted and measured concentrations of Fe++ and Fe3+ in ionized nebulae. We calculate a set of photoionization models, updated with the atomic data relevant to the problem, and compare their results ... More
A Cloudy Bag Model for the S-D Wave $\Kbar-N$ SystemAug 02 1993Aug 09 1993The cloudy quark bag model is applied to the coupled ($\Kbar N$, $\Sigma \pi$, $\Lambda \pi$) system for $S-D$ partial waves. Energy--dependent separable potentials are derived, as are new numerical algorithms for solving the coupled Lippmann-Schwinger ... More
Distinction of Tripartite Greenberger-Horne-Zeilinger and W States Entangled in Time (or Energy) and SpaceMar 13 2009In tripartite discrete systems, two classes of genuine tripartite entanglement have been discovered, namely, the Greenberger-Horne-Zeilinger (GHZ) class and the W class. To date, much research effort has been concentrated on the polarization entangled ... More
The Theory of Two-Photon Interference in an EIT SystemJun 22 2004Jun 23 2004We examine the possibility of storing and retrieving a single photon using electromagnetically induced transparency (EIT). We consider the theory of a proof of principle two-photon interference experiment, in which an atomic vapor cell is placed in one ... More
Simultaneous Z/p-acyclic resolutions of expanding sequencesJan 13 2011Jan 28 2013We prove the following Theorem: Let X be a nonempty compact metrizable space, let $l_1 \leq l_2 \leq...$ be a sequence of natural numbers, and let $X_1 \subset X_2 \subset...$ be a sequence of nonempty closed subspaces of X such that for each k in N, ... More
Neutral Hydrogen Clouds in the M81/M82 GroupMar 25 2008We have observed a 3 degree x 3 degree area centered on the M81/M82 group of galaxies using the Robert C. Byrd Green Bank Telescope (GBT) in a search for analogs to the High Velocity Clouds (HVCs) of neutral hydrogen found around our galaxy. The velocity ... More
Possible Signature of Low Scale Gravity in Ultra High Enegry Cosmic RaysMay 10 2000We show that the existence of low scale gravity at TeV scale could lead to a direct production of photons with energies above 10^22 eV due to annihilation of ultra high energy neutrinos on relic massive neutrinos of the galactic halo. Air showers initialized ... More
Stellar Seismology, Stellar Ages and the Cosmological ConstantSep 25 2001Solar seismology has allowed precision measurements of both the static and dynamic structure of our local star, the Sun. In the near future, seismology of solar-like stars of different ages and masses, necessarily restricted by angular resolution to low ... More
Signpost of Multiple Planets in Debris DisksJul 05 2013We review the nearby debris disk structures revealed by multi-wavelength images from Spitzer and Herschel, and complemented with detailed spectral energy distribution modeling. Similar to the definition of habitable zones around stars, debris disk structures ... More
Beyond the effective mass approximation: predictive theory of the nonlinear optical response of conduction electronsSep 28 2016We present an experimental and computational study of the nonlinear optical response of conduction electrons to intense terahertz (THz) electric field. Our observations (saturable absorption and an amplitude-dependent group refractive index) can be understood ... More
Statistics of Turbulence Parameters at Maunakea using multiple wave-front sensor data of RAVENOct 17 2016Prior statistical knowledge of the atmospheric turbulence is essential for designing, optimizing and evaluating tomographic adaptive optics systems. We present the statistics of the vertical profiles of $C_N^2$ and the outer scale at Maunakea estimated ... More
Multi time-step wave-front reconstruction for tomographic Adaptive-Optics systemsApr 11 2016In tomographic adaptive-optics (AO) systems, errors due to tomographic wave-front reconstruction limit the performance and angular size of the scientific field of view (FoV), where AO correction is effective. We propose a multi time-step tomographic wave-front ... More
Separability and Fourier representations of density matricesJan 07 2000Using the finite Fourier transform, we introduce a generalization of Pauli-spin matrices for $d$-dimensional spaces, and the resulting set of unitary matrices $S(d) $ is a basis for $d\times d$ matrices. If $N=d_{1}\times d_{2}\times...\times d_{b}$ and ... More
Breit-Pauli energy levels, transition probabilities, and lifetimes for 3d^5 levels in Fe IV of astrophysical interestAug 24 2004Energy levels, lifetimes, and transition probabilities for transitions between computed levels of 3d^5 of Fe IV are reported. The E2 and M1 transition probabilities are compared with earlier theoretical results, often only the values published by Garstang ... More
Effects of mismatched transmissions on two-mode squeezing and EPR correlations with a slow light mediumApr 21 2005Jul 05 2005We theoretically discuss the preservation of squeezing and continuous variable entanglement of two mode squeezed light when the two modes are subjected to unequal transmission. One of the modes is transmitted through a slow light medium while the other ... More
Spatial Resolution Enhancement in Quantum Imaging beyond the Diffraction Limit Using Entangled Photon-Number StateDec 10 2008Dec 12 2008In this paper we study the resolution of images illuminated by sources composed of $N+1$ photons in which one non-degenerate photon is entangled with $N$ degenerate photons. The $N$ degenerate photons illuminate an object and are collected by an $N$ photon ... More
Role of quantum fluctuations at high energiesJul 08 2002We investigate an influence of virtual particles on the classical motion of a system in Minkowski and Euclidean spaces. Our results indicate that fluctuations of fields different from the main field decelerate significantly its motion at high energies. ... More
Mutually Unbiased Bases, Generalized Spin Matrices and SeparabilityAug 26 2003Apr 21 2004A collection of orthonormal bases for a complex dXd Hilbert space is called mutually unbiased (MUB) if for any two vectors v and w from different bases the square of the inner product equals 1/d: |<v,w>| ^{2}=1/d. The MUB problem is to prove or disprove ... More
Note on Separability of the Werner states in arbitrary dimensionsJan 30 2000Feb 25 2000Great progress has been made recently in establishing conditions for separability of a particular class of Werner densities on the tensor product space of $n$ $d$--level systems (qudits). In this brief note we complete the process of establishing necessary ... More
Complete Separability and Fourier representations of n-qubit statesDec 28 1999Necessary conditions for separability are most easily expressed in the computational basis, while sufficient conditions are most conveniently expressed in the spin basis. We use the Hadamard matrix to define the relationship between these two bases and ... More
Convexity and the Separability Problem of Quantum Mechanical Density MatricesMar 08 2001A finite dimensional quantum mechanical system is modeled by a density rho, a trace one, positive semi-definite matrix on a suitable tensor product space H[N] . For the system to demonstrate experimentally certain non-classical behavior, rho cannot be ... More
Cosmological dynamics of scalar field with non-minimal kinetic termOct 07 2003Dec 15 2003We investigate dynamics of scalar field with non-minimal kinetic term. Nontrivial behavior of the field in the vicinity of singular points of kinetic term is observed. In particular, the singular points could serve as attractor for classical solutions. ... More
Wigner Functions and Separability for Finite SystemsJan 19 2005Jun 22 2005A discussion of discrete Wigner functions in phase space related to mutually unbiased bases is presented. This approach requires mathematical assumptions which limits it to systems with density matrices defined on complex Hilbert spaces of dimension p^n ... More
A Debris Disk around the Central Star of the Helix Nebula?Feb 11 2007Excess emission from a point-like source coincident with the central star of the Helix Nebula is detected with Spitzer at 8, 24, and 70 um. At 24 um, the central source is superposed on an extended diffuse emission region. While the [OIV] 25.89 um line ... More
Stellar Motions in the Polar Ring Galaxy NGC 4650AMar 06 2003We present the first measurement of the stellar kinematics in the polar ring of NGC 4650A. There is well defined rotation, with the stars and gas rotating in the same direction, and with similar amplitude. The gaseous and stellar kinematics suggest an ... More
The Nature and Frequency of Outflows from Stars in the Central Orion Nebula ClusterAug 14 2015Recent Hubble Space Telescope images have allowed the determination with unprecedented accuracy of motions and changes of shocks within the inner Orion Nebula. These originate from collimated outflows from very young stars, some within the ionized portion ... More
Equilibrium Properties of Temporally Asymmetric Hebbian PlasticityJul 25 2000Sep 08 2000A theory of temporally asymmetric Hebb (TAH) rules which depress or potentiate synapses depending upon whether the postsynaptic cell fires before or after the presynaptic one is presented. Using the Fokker-Planck formalism, we show that the equilibrium ... More
The geometry of entanglement witnesses and local detection of entanglementJul 03 2002Let $H^{[ N]}=H^{[ d_{1}]}\otimes ... \otimes H^{[ d_{n}]}$ be a tensor product of Hilbert spaces and let $\tau_{0}$ be the closest separable state in the Hilbert-Schmidt norm to an entangled state $\rho_{0}$. Let $\tilde{\tau}_{0}$ denote the closest ... More
Narrow-Band Biphoton Generation near Atomic ResonanceApr 24 2008Generating nonclassical light offers a benchmark tool for the fundamental research and potential applications in quantum optics. Conventionally, it has become a standard technique to produce the nonclassical light through the nonlinear optical processes ... More
Infrared Spectroscopy of Atomic Lines in Gaseous NebulaeSep 23 2001Spectroscopy in the infrared provides a means to assess important properties of the plasma in gaseous nebulae. We present some of our own work that illustrates the need for interactions between the themes of this conference - astronomical data, atomic ... More
Probing the Interstellar Medium in Early type galaxies with ISO observationsJun 23 2000Four IRAS-detected early type galaxies were observed with ISO. With the exception of the 15 micron image of NGC1052, the mid-IR emission from NGC1052, NGC1155, NGC5866 and NGC6958 at 4.5, 7 and 15 microns show extended emission. Mid-IR emission from NGC1052, ... More
Suppressing star formation in quiescent galaxies with supermassive black hole windsMay 24 2016Quiescent galaxies with little or no ongoing star formation dominate the galaxy population above $M_{*}\sim 2 \times 10^{10}~M_{\odot}$, where their numbers have increased by a factor of $\sim25$ since $z\sim2$. Once star formation is initially shut down, ... More
Spitzer Mid-Infrared Spectroscopy of Distant X-ray Luminous AGNJan 30 2008We present mid-infrared spectroscopy of a sample of 16 optically faint infrared luminous galaxies obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. These sources were jointly selected from Spitzer and Chandra imaging surveys ... More
Deviations from He I Case B Recombination Theory and Extinction Corrections in the Orion NebulaOct 20 2006We are engaged in a comprehensive program to find reliable elemental abundances in and to probe the physical structure of the Orion Nebula, the brightest and best-resolved H II region. In the course of developing a robust extinction correction covering ... More
The Inner 25 AU Debris Distribution in the epsilon Eri SystemMar 30 2017Debris disk morphology is wavelength dependent due to the wide range of particle sizes and size-dependent dynamics influenced by various forces. Resolved images of nearby debris disks reveal complex disk structures that are difficult to distinguish from ... More
The Structure of the β Leonis Debris DiskSep 30 2010We combine nulling interferometry at 10 {\mu}m using the MMT and Keck Telescopes with spectroscopy, imaging, and photometry from 3 to 100 {\mu}m using Spitzer to study the debris disk around {\beta} Leo over a broad range of spatial scales, corresponding ... More
The Lexington Benchmarks for Numerical Simulations of NebulaeMar 29 2016We present the results of a meeting on numerical simulations of ionized nebulae held at the University of Kentucky in conjunction with the celebration of the 70th birthdays of Profs. Donald Osterbrock and Michael Seaton.
Temperature Variations from HST Spectroscopy of the Orion NebulaDec 10 2002We present HST/STIS long-slit spectroscopy of NGC 1976. Our goal is to measure the intrinsic line ratio [O III] 4364/5008 and thereby evaluate the electron temperature (T_e) and the fractional mean-square T_e variation (t_A^2) across the nebula. We also ... More
High-Precision Scanning Water Vapor Radiometers for Cosmic Microwave Background Site Characterization and ComparisonAug 03 2018The compelling science case for the observation of B-mode polarization in the cosmic microwave background (CMB) is driving the CMB community to expand the observed sky fraction, either by extending survey sizes or by deploying receivers to potential new ... More
Spitzer Mid-Infrared Spectroscopy of 70um-Selected Distant Luminous Infrared GalaxiesSep 20 2007We present mid-infrared spectroscopy obtained with the Spitzer Space Telescope of a sample of 11 optically faint, infrared luminous galaxies selected from a Spitzer MIPS 70um imaging survey of the NDWFS Bootes field. These are the first Spitzer IRS spectra ... More
Could the planets around HR 8799 be brown dwarfs?Aug 30 2010We consider the limiting case for orbital stability of the companions to HR 8799. This case is only consistent with ages for the system of ~100 Myr, not with the 1 Gyr age proposed from astroseismology. The discrepancy probably arises because the inclination ... More
Far Infrared Spectroscopy of Normal Galaxies: Physical Conditions in the Interstellar MediumJun 27 2001The most important cooling lines of the neutral interstellar medium (ISM) lie in the far-infrared (FIR). We present measurements by the Infrared Space Observatory Long Wavelength Spectrometer of seven lines from neutral and ionized ISM of 60 normal, star-forming ... More
Plasma Density Structures at Comet 67P/Churyumov-GerasimenkoMar 23 2018We present Rosetta RPC case study from four events at various radial distance, phase angle and local time from autumn 2015, just after perihelion of comet 67P/Churyumov-Gerasimenko. Pulse like (high amplitude, up to minutes in time) signatures are seen ... More
ISO--LWS observations of the two nearby spiral galaxies: NGC6946 and NGC1313Apr 15 2002(Abridged) We present the analysis of the main FIR fine structure lines emission in NGC1313 and NGC6946. We calculate that a component probably associated with the diffuse disks contributes <~40% in N6946 and ~30 % in N1313 to the total [CII] emission. ... More
Hydrodynamical simulations of galaxy formation: effects of supernova feedbackMay 29 1996May 30 1996We numerically simulate some of the most critical physical processes in galaxy formation: The supernova feedback, in conjunction with gasdynamics and gravity, plays a crucial role in determining how galaxies arise within the context of a model for large-scale ... More
Nanosized helical magnetic domains in strongly frustrated Fe3PO4O3Sep 25 2015Feb 02 2016Fe3PO4O3 forms a non-centrosymmetric lattice structure (space group R3m) comprising triangular motifs of Fe^{3+} coupled by strong antiferromagnetic interactions (|\Theta_{CW}| > 900 K). Neutron diffraction from polycrystalline samples shows that strong ... More
Hydrodynamical simulations of galaxy properties: Environmental effectsSep 10 1998Using N-body+hydro simulations we study relations between the local environments of galaxies on 0.5 Mpc scale and properties of the luminous components of galaxies. Our numerical simulations include effects of star formation and supernova feedback in ... More
The 3-D clustering of radio galaxies in the TONS surveyDec 09 2004We present a clustering analysis of the Texas-Oxford NVSS Structure (TONS) radio galaxy redshift survey. This complete flux-limited survey consists of 268 radio galaxies with spectroscopic redshifts in three separate regions of the sky covering a total ... More
Kinematic Disturbances in Optical Rotation Curves among 89 Virgo Disk GalaxiesApr 03 1999For 89 galaxies, mostly spirals, in the Virgo cluster region, we have obtained optical long-slit major axis spectra of the ionized gas. We find: (1) One-half of the Virgo galaxies we observed have regular rotation patterns, while the other 50% exhibit ... More
The spin of prime idealsOct 28 2011Oct 22 2012Fixing a nontrivial automorphism of a number field K, we associate to ideals in K an invariant (with values in {0,1,-1}) that we call the "spin" and for which the associated L-function does not possess Euler products. We are nevertheless able, using the ... More
Limitations in Predicting the Space Radiation Health Risk for Exploration AstronautsOct 19 2017Feb 17 2018Despite years of research, understanding of the space radiation environment and the risk it poses to long-duration astronauts remains limited. There is a disparity between research results and observed empirical effects seen in human astronaut crews, ... More
Spitzer reveals what's behind Orion's BarAug 16 2010We present Spitzer Space Telescope observations of 11 regions SE of the Bright Bar in the Orion Nebula, along a radial from the exciting star theta1OriC, extending from 2.6 to 12.1'. Our Cycle 5 programme obtained deep spectra with matching IRS short-high ... More
ISOCAM Observations of NGC 6946: Mid-IR StructureOct 29 1996The nearby spiral galaxy NGC 6946 was observed with ISO-CAM in the mid-infrared, achieving 7 arcsec resolution and sub-MJy/steradian sensitivity. Images taken with CAM filters LW2 (7 microns) and LW3 (15 microns) are analysed to determine the morphology ... More
Two-Photon Beatings Using Biphotons Generated from a Two-Level SystemJul 25 2008We propose a two-photon beating experiment based upon biphotons generated from a resonant pumping two-level system operating in a backward geometry. On the one hand, the linear optical-response leads biphotons produced from two sidebands in the Mollow ... More
Self-regulating galaxy formation as an explanation for the Tully-Fisher relationAug 25 1998Using 3D hydrodynamical simulations of galaxy formation with supernova feedback and a multiphase medium, we derive theoretical relations analogous to the observed Tully-Fisher (TF) relations in various photometric bands. This paper examines the influence ... More
Dense Distributions from Sparse Samples: Improved Gibbs Sampling Parameter Estimators for LDAMay 08 2015Apr 11 2017We introduce a novel approach for estimating Latent Dirichlet Allocation (LDA) parameters from collapsed Gibbs samples (CGS), by leveraging the full conditional distributions over the latent variable assignments to efficiently average over multiple samples, ... More
Cosmological implications of Higgs field fluctuations during inflationOct 05 2016Cosmological implications of Higgs field fluctuations during inflation are considered. This study is based on the Standard Model and the standard quadratic model of chaotic inflation where the Higgs field is minimally coupled to gravity and has no direct ... More