Physical Sciences and Mathematics Commons^™

Mass-Loss And Magnetospheres: X-Rays From Hot Stars And Young Stellar Objects, M. Gagné, David H. Cohen, S. P. Owocki, A. Ud-Doula

Physics & Astronomy Faculty Works

High-resolution X-ray spectra of high-mass stars and low-mass T-Tauri stars obtained during the first year of the Chandra mission are providing important clues about the mechanisms which produce X-rays on very young stars. For zeta Puppis (O4 If) and zeta Ori (O9.5 I), the broad, blue-shifted line profiles, line ratios, and derived temperature distribution suggest that the X-rays are produced throughout the wind via instability-driven wind shocks. For some less luminous OB stars, like theta^1 Ori C (O7 V) and tau Sco (B0 V), the line profiles are symmetric and narrower. The presence of time-variable emission and very high-temperature lines …

An Upper Limit To The Age Of The Galactic Bar, Aa Cole, Md Weinberg

Astronomy Department Faculty Publication Series

Using data from the Two Micron All Sky Survey, we identify a population of infrared carbon stars with J-KS ≥ 2 in the Milky Way. These stars are shown to trace the stellar bar previously identified in IR and optical surveys. The properties of C stars strongly suggest that they are of intermediate age. We conclude that the bar is likely to have formed more recently than 3 Gyr ago and must be younger than 6 Gyr. Implications and further tests of this conclusion are briefly discussed.

Sensitive Limits On The Water Abundance In Cold Low-Mass Molecular Cores, Ea Bergin, Ronald L. Snell

Astronomy Department Faculty Publication Series

We present Submillimeter Wave Astronomy Satellite observations of water vapor in two cold starless clouds, B68 and core D in ρ Ophiuchi. Sensitive nondetections of the 1₁₀-1₀₁ transition of o-H₂O are reported for each source. Both molecular cores have been previously examined by detailed observations that have characterized the physical structure. Using these rather well-defined physical properties and a Monte Carlo radiation transfer model, we have removed one of the largest uncertainties from the abundance calculation and set the lowest water abundance limit to date in cold low-mass molecular cores. These limits are x(o-H …

The Growth Of Galaxies In Cosmological Simulations, Jh Choi, N Katz, C Murali, D Weinberg, R Dave, L Hernquist

Astronomy Department Faculty Publication Series

We use hydrodynamic simulations to examine how the baryonic components of galaxies are assembled, focusing on the relative importance of mergers and smooth accretion in the formation of ~L_* systems. In our primary simulation, which models a (50 h^-1 Mpc)³ comoving volume of a Λ-dominated cold dark matter universe, the space density of objects at our (64 particle) baryon mass resolution threshold M_c = 5.4 × 10¹⁰ M corresponds to that of observed galaxies with L ~ L_*/4. Galaxies above this threshold gain most of their mass by accretion rather than by …

High-Redshift Galaxies In Cold Dark Matter Models, Dh Weinberg, L Hernquist, N Katz

Astronomy Department Faculty Publication Series

We use hydrodynamic cosmological simulations to predict the star formation properties of high-redshift galaxies (z = 2-6) in five variants of the inflationary cold dark matter scenario, paying particular attention to z = 3, the redshift of the largest "Lyman break galaxy" (LBG) samples. Because we link the star formation timescale to the local gas density, the rate at which a galaxy forms stars is governed mainly by the rate at which it accretes cooled gas from the surrounding medium. At z = 3, star formation in most of the simulated galaxies is steady on ~200 Myr timescales, and …

X-Ray Scaling Relations Of Galaxy Groups In A Hydrodynamic Cosmological Simulation, R Dave, N Katz, Dh Weinberg

Astronomy Department Faculty Publication Series

We examine the scalings of X-ray luminosity, temperature, and dark matter or galaxy velocity dispersion for galaxy groups in a ΛCDM cosmological simulation, which incorporates gravity, gas dynamics, radiative cooling, and star formation, but no substantial nongravitational heating. In agreement with observations, the simulated L_X-σ and L_X-T_X relations are steeper than those predicted by adiabatic simulations or self-similar models, with L_X σ^4.4 and L_X T for massive groups and significantly steeper relations below a break at σ 180 km s^-1 (T_X 0.7 keV). The T_X-σ relation …

Title: Chandra Observations Of The Galactic Center And Nearby Edge-On Galaxies, Qd Wang

Astronomy Department Faculty Publication Series

I review our recent Chandra surveys of the center region of the Milky Way and other nearby edge-on galaxies. Our Galactic center survey provides an unprecedented high-resolution, broad-band X-ray panorama of a 0.8x2 square degree swath along the Galactic plane. Our preliminary analysis has led a detection of about 1000 discrete sources. We find that the diffuse X-ray emission dominates over the contribution from faint discrete sources and is globally associated with distinct interstellar structures observed at radio and mid-infrared wavelengths. We study how high-energy activities in the center region affect the immediate vicinity and may influence other aspects of …

The Nature Of The Faint Far-Infrared Extragalactic Source Population: Optical/Nir And Radio Follow-Up Observationts Of Isophot Deep-Field Sources Using The Keck, Subaru, And Vla Telescopes., Y Kakazu, Db Sanders, Rd Joseph, Ll Cowie, T Murayama, Y Taniguchi, S Veilleux, Min Yun, K Kawara, Y Sofue, Y Sato, H Okuda, K Wakamatsu, T Matsumoto, H Matsuhara

Astronomy Department Faculty Publication Series

In order to search for obscured objects at high redshifts, we have made deep far-infrared (FIR) deep survey in the Lockman Hole using ISOPHOT onboard ISO (Kawara et al. 1998, A&A, 336, L9). In this survey several tens of FIR sources have been found at 95micron and 175micron. Here we present results of optical and NIR spectroscopic followup observations performed at the W. M.Keck Observatory.

High-Resolution Imaging Of Molecular Line Emission From High-Redshift Qsos, Cl Carilli, K Kohno, R Kawabe, K Ohta, C Henkel, Km Menten, Min Yun, A Petric, Y Tutui

Astronomy Department Faculty Publication Series

We present moderate- (1'') and high-resolution (02) observations of the CO (2–1) emission at 43 GHz and radio continuum emission at 1.47 GHz from the z = 4.7 QSO BRI 1202-0725 and the z = 4.4 QSO BRI 1335-0417 using the Very Large Array. The moderate-resolution observations show that in both cases the CO emission is spatially resolved into two components separated by 1'' for BRI 1335-0417 and 4'' for BRI 1202-0725. The high-resolution observations show that each component has substructure on scales ~02–05, with intrinsic brightness temperatures ≥20 K. The CO ladder from (2–1) up to (7–6) suggests a …

Detection Of Infall Signatures Toward Serpens Smm4, Gopal Narayanan, G Moriarty-Schieven, Ck Walker, Hm Butner

Astronomy Department Faculty Publication Series

We present the detection of kinematic infall signatures toward the Class 0 protostellar system SMM4 in the Serpens cloud core. We have observed the dense molecular gas toward the embedded source using millimeter and submillimeter line transitions of density sensitive molecular tracers. High signal-to-noise ratio maps obtained in HCO⁺ J = 1 → 0, J = 3 → 2, and J = 4 → 3, and CS J = 2 → 1 show the blue-bulge infall signature. The blue-bulge infall signature can be observed in the centroid velocity maps of protostellar objects when infall dominates over rotation. The line …

Physical Parameter Eclipse Mapping Of The Quiescent Disc In V2051 Ophiuchi, S Vrielmann, R Stiening, W Offutt

Astronomy Department Faculty Publication Series

We analyse simultaneous UBVR quiescent light curves of the cataclysmic variable V2051 Oph using the Physical Parameter Eclipse Mapping (PPEM) method in order to map the gas temperature and surface density of the disc for the first time. The disc appears optically thick in the central regions, and gradually becomes optically thin towards the disc edge or shows a more and more dominating temperature inversion in the disc chromosphere. The gas temperatures in the disc range from about 13 500 K near the white dwarf to about 6000 K at the disc edge. The intermediate part of the disc has …

Discovery Of A 136 Millisecond Radio And X-Ray Pulsar In Supernova Remnant G54.1+0.3, F Camilo, Dr Lorimer, Ndr Bhat, Ev Gotthelf, Jp Halpern, Qd Wang, Fj Lu, N Mirabal

Astronomy Department Faculty Publication Series

We report the discovery of a pulsar with period P = 136 ms and dispersion measure 308 cm^-3 pc in a deep observation of the supernova remnant (SNR) G54.1+0.3 with the Arecibo radio telescope. Timing measurements of the new pulsar, J1930+1852, reveal a characteristic age of P/2 = 2900 yr and a spin-down luminosity of = 1.2 × 10³⁷ ergs s^-1. We have subsequently searched archival ASCA X-ray data of this SNR and detect pulsations with a consistent period. These findings ensure that PSR J1930+1852 is the pulsar that powers the "Crab-like" SNR G54.1+0.3. Together …

Chandra Observations Of The Bursting X-Ray Transient Sax J1747.0–2853 During Low-Level Accretion Activity, R Wijnands, Jm Miller, Qd Wang

Astronomy Department Faculty Publication Series

We present Chandra/ACIS observations of the bursting X-ray transient SAX J1747.0-2853 performed on 2001 July 18. We detected a bright source at the position of R.A. = 17^h47^m02.s60 and decl. = -28°52'589 (J2000.0, with a 1 σ error of ~07), consistent with the BeppoSAX and ASCA positions of SAX J1747.0-2853 and with the Ariel V position of the transient GX +0.2-0.2, which was active during the 1970s. The 0.5-10 keV luminosity of the source during our observations was ~ 3 × 10³⁵ ergs s^-1 (assuming a distance of 9 kpc), demonstrating that the …

X-Ray Thread G0.13–0.11: A Pulsar Wind Nebula?, Qd Wang, F Lu, Cc Lang

Astronomy Department Faculty Publication Series

We have examined Chandra observations of the recently discovered X-ray thread G0.13-0.11 in the Galactic center Radio Arc region. Part of the Chandra data was studied by Yusef-Zadeh, Law, & Wardle, who reported the detection of 6.4 keV line emission in this region. We find, however, that this line emission is not associated with G0.13-0.11. The X-ray spectrum of G0.13-0.11 is well-characterized by a simple power law with an energy slope of 1.8 (90% confidence uncertainties). Similarly, the X-ray spectrum of the pointlike source embedded in G0.13-0.11 has a power-law energy slope of 0.9. The 2-10 keV band luminosities of …

Bouncing Branes, Emil Prodanov

Articles

Two classical scalar fields are minimally coupled to gravity in the Kachru-Shulz-Silverstein scenario with a rolling fifth radius. A Tolman wormhole solution is found for a R x S^3 brane with Lorentz metric and for a R x AdS_3 brane with positive definite metric.

Fluorescence And Chromospheric Activity Of V471 Tau, Todd R. Vaccaro, Robert E. Wilson

Physics and Astronomy Faculty Publications

The red dwarf + white dwarf eclipsing binary V471 Tau shows a variable Hα feature that varies from absorption during eclipse to maximum emission during white dwarf transit. In 1998 we obtained simultaneous BVRI photometry and Hα spectroscopy, with thorough phase coverage of the 12.5 hour orbital period. A binary star model was used with our light curve, radial velocity, and Hα data to refine stellar and orbital parameters. Combined absorption-emission profiles were generated by the model and fit to the observations, yielding a red star radius of 0.94⊙. Orbital inclination 78° is required with this size and other known …

Detection Of X-Ray Emission From The Arches Cluster Near The Galactic Center, F Yusef-Zadeh, C Claw, M Wardle, Qd Wang, A Fruscione, Cc Lang, A Cortera

Astronomy Department Faculty Publication Series

The Arches cluster is an extraordinarily compact massive star cluster with a core radius of about 10'' (~0.4 pc) and consisting of more than 150 O star candidates with initial stellar masses greater than 20 M near G0.12-0.02. X-ray observations of the radio Arc near the Galactic center at l ~ 02, which contains the Arches cluster, have been carried out with the Advanced CCD Imaging Spectrometer (ACIS) on board Chandra X-Ray Observatory. We report the detection of two X-ray sources from the Arches cluster embedded within a bath of diffuse X-ray emission extending beyond the edge of the …

Chandra Observation Of Supernova Remnant G54.1+0.3: A Close Cousin Of The Crab Nebula, Fj Lu, Qd Wang, B Aschenbach, P Durouchoux, Lm Song

Astronomy Department Faculty Publication Series

We present a Chandra Advanced CCD Imaging Spectrometer observation of supernova remnant G54.1+0.3. This supernova remnant is resolved into several distinct X-ray-emitting components: a central bright pointlike source (CXOU J193030.13+185214.1), a surrounding ring, bipolar elongations, plus low surface brightness diffuse emission. The spectra of these components are all well described by power-law models; the spectral index steepens with increasing distance from the pointlike source. We find no evidence for any thermal plasma emission that would correspond to shocked interstellar medium or ejecta. The observed morphological and spectral characteristics suggest that G54.1+0.3 is the closest "cousin" of the Crab Nebula—a pulsar …

Negative-Parity Baryon Masses Using An O(A)-Improved Fermion Action, M. Göckeler, R. Horsley, D. Pleiter, P. E. L. Rakow, G. Schierholz, C. M. Maynard, D. G. Richards

Physics Faculty Publications

We present a calculation of the mass of the lowest-lying negative-parity J=1/2− state in quenched QCD. Results are obtained using a non-perturbatively O(a)-improved clover fermion action, and a splitting is found between the mass of the nucleon, and its parity partner. The calculation is performed on two lattice volumes and at three lattice spacings, enabling a study of both finite-volume and finite lattice-spacing uncertainties. A comparison is made with results obtained using the unimproved Wilson fermion action.

Hiccups In The Night: X-Ray Monitoring Of The Two Crab-Like Lmc Pulsars, Ev Gotthelf, W Zhang, Fe Marshall, J Middleditch, Qd Wang

Astronomy Department Faculty Publication Series

We are undertaking an extensive X-ray monitoring campaign of the two Crab-like pulsars in the Large Magellanic Clouds, PSR B0540-69 and PSR J0537-6910. We present our current phase-connected timing analysis derived from a set of 50 pointed X-ray observations spanning several years. From our initial 1.2 yr monitoring program of the young 50 ms pulsar PSR B0540-69, we find the first compelling evidence for a glitch in its rotation. This glitch is characterized by Delta nu / nu = (1.90+-0.05) x 10^-9 and Delta nu_dot / nu_dot = (8.5+-0.5) x 10^-5. Taking into account the …

Comment On ‘‘Stress-Density Ratio Slip-Corrected Reynolds Equation For Ultra-Thin Film Gas Bearing Lubrication’’, Alejandro Garcia

Faculty Publications

No abstract provided.

Proceedings Of The First International Conference On Neutrosophy, Neutrosophic Logic, Neutrosophic Set, Neutrosophic Probability And Statistics, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

In 1960s Abraham Robinson has developed the non-standard analysis, a formalization of analysis and a branch of mathematical logic, that rigorously defines the infinitesimals. Informally, an infinitesimal is an infinitely small number. Formally, x is said to be infinitesimal if and only if for all positive integers n one has xxx < 1/n. Let &>0 be a such infinitesimal number. The hyper-real number set is an extension of the real number set, which includes classes of infinite numbers and classes of infinitesimal numbers. Let’s consider the non-standard finite numbers 1+ = 1+&, where “1” is its standard part and “&” its non-standard part, …

Tightness Of Slip-Linked Polymer Chains, Ralf Metzler, Andreas Hanke, Paul G. Dommersnes, Yacov Kantor, Mehran Kardar

Physics and Astronomy Faculty Publications and Presentations

We study the interplay between entropy and topological constraints for a polymer chain in which sliding rings (slip links) enforce pair contacts between monomers. These slip links divide a closed ring polymer into a number of subloops which can exchange length among each other. In the ideal chain limit, we find the joint probability density function for the sizes of segments within such a slip-linked polymer chain (paraknot). A particular segment is tight (small in size) or loose (of the order of the overall size of the paraknot) depending on both the number of slip links it incorporates and its …

The Lisa Optimal Sensitivity, Thomas A. Prince, Massimo Tinto, Shane L. Larson, J. W. Armstrong

All Physics Faculty Publications

The multiple Doppler readouts available on the Laser Interferometer Space Antenna (LISA) permit simultaneous formation of several interferometric observables. All these observables are independent of laser frequency fluctuations and have different couplings to gravitational waves and to the various LISA instrumental noises. Within the functional space of interferometric combinations LISA will be able to synthesize, we have identified a triplet of interferometric combinations that show optimally combined sensitivity. As an application of the method, we computed the sensitivity improvement for sinusoidal sources in the nominal, equal-arm LISA configuration. In the part of the Fourier band where the period of the …

Group-Fitted Ab Initio Single- And Multiple-Scattering Exafs Debye-Waller Factors, N. Dimakis, Grant Bunker

Physics and Astronomy Faculty Publications and Presentations

X-ray absorption fine structure (XAFS) spectroscopy is one of the few direct probes of the structure of metalloprotein binding that is equally applicable to proteins in crystals, solutions, and membranes. Despite considerable progress in the calculation of the photoelectron scattering aspects of XAFS, calculation of the vibrational aspects has lagged because of the difficulty of the calculations. We report here initial results that express single- and multiple-scattering Debye-Waller factors as polynomial functions of first shell radial distance for metal-peptide complexes, enabling quantitatively accurate full multiple-scattering XAFS data analysis of active sites of unknown structure at arbitrary temperatures without the use …

Correlation Functions Near Modulated And Rough Surfaces, Andreas Hanke, Mehran Kardar

Physics and Astronomy Faculty Publications and Presentations

In a system with long-ranged correlations, the behavior of correlation functions is sensitive to the presence of a boundary. We show that surface deformations strongly modify this behavior as compared to a flat surface. The modified near surface correlations can be measured by scattering probes. To determine these correlations, we develop a perturbative calculation in the deformations in height from a flat surface. Detailed results are given for a regularly patterned surface, as well as for a self-affinely rough surface with roughness exponent ζ. By combining this perturbative calculation in height deformations with the field-theoretic renormalization-group approach, we also estimate …

Book Review: The Observing Guide To The Messier Marathon: A Handbook And Atlas, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of The Observing Guide to the Messier Marathon : a Handbook and Atlas by Don Machholz. Cambridge, 2002 157p, 0-521-80386-1 $25.00.

Book Review: Flash!: The Hunt For The Biggest Explosions In The Universe, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Flash! : the hunt for the biggest explosions in the universe by Govert Schilling. tr. by Naomi Greenberg-Slovin Cambridge, 2002 291p, 0-521-80053-6 $28.00

Wiyn Open Cluster Study Xi: Wiyn1 3.5m Deep Photometry Of M35 (Ngc 2168), Ted Von Hippel, Aaron Steinhauer, Ata Sarajedini, Constantine P. Deliyannis

Publications

We present deep BV I observations of the core of M35 and a nearby comparison field obtained at the WIYN 3.5m telescope under excellent seeing conditions. These observations probe to V > 26, and display the lower main sequence in BV and V I CMDs down to V = 23.3 and 24.6, respectively. At these faint magnitudes the background Galactic field stars are far more numerous than the cluster stars, yet by using a smoothing technique and CMD density distribution subtraction we are able to recover the cluster fiducial main sequence and luminosity function to V = 24.6. We find the …

Unequal Arm Space-Borne Gravitational Wave Detectors, Shane L. Larson, Ronald W. Hellings, William A. Hiscock

All Physics Faculty Publications

Unlike ground-based interferometric gravitational wave detectors, large space-based systems will not be rigid structures. When the end stations of the laser interferometer are freely flying spacecraft, the armlengths will change due to variations in the spacecraft positions along their orbital trajectories, so the precise equality of the arms that is required in a laboratory interferometer to cancel laser phase noise is not possible. However, using a method discovered by Tinto and Armstrong, a signal can be constructed in which laser phase noise exactly cancels out, even in an unequal arm interferometer. We examine the case where the ratio of the …