Astrophysics and Astronomy Commons^™

Spatially Resolving The Very High Energy Emission From Mgro J2019+37 With Veritas, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We present very high energy (VHE) imaging of MGRO J2019+37 obtained with the VERITAS observatory. The bright extended (~2°) unidentified Milagro source is located toward the rich star formation region Cygnus-X. MGRO J2019+37 is resolved into two VERITAS sources. The faint, point-like source VER J2016+371 overlaps CTB 87, a filled-center remnant (SNR) with no evidence of a supernova remnant shell at the present time. Its spectrum is well fit in the 0.65-10 TeV energy range by a power-law model with photon index 2.3 ± 0.4. VER J2019+378 is a bright extended (~1°) source that likely accounts for the bulk of …

Subaru Spectroscopy And Spectral Modeling Of Cygnus A, Matthew J. Merlo, Eric S. Perlman, Robert Nikutta, Christopher Packham, Moshe Elitzur, Masatoshi Imanishi, Nancy A. Levenson, James T. Radomski, Itziar Aretxaga

Aerospace, Physics, and Space Science Faculty Publications

We present high angular resolution (∼0.″5) MIR spectra of the powerful radio galaxy, Cygnus A (Cyg A), obtained with the Subaru telescope. The overall shape of the spectra agree with previous high angular resolution MIR observations, as well as previous Spitzer spectra. Our spectra, both on and off nucleus, show a deep silicate absorption feature. The absorption feature can be modeled with a blackbody obscured by cold dust or a clumpy torus. The deep silicate feature is best fit by a simple model of a screened blackbody, suggesting that foreground absorption plays a significant, if not dominant, role in shaping …

Obscuration By Gas And Dust In Luminous Quasars, S. M. Usman, S. S. Murray, R. C. Hickox, M. Brodwin

Dartmouth Scholarship

We explore the connection between absorption by neutral gas and extinction by dust in mid-infrared (IR) selected luminous quasars. We use a sample of 33 quasars at redshifts 0.7 < z < 3 in the 9 deg^2 Bo\"otes multiwavelength survey field that are selected using Spitzer Space Telescope Infrared Array Camera colors and are well-detected as luminous X-ray sources (with >150 counts) in Chandra observations. We divide the quasars into dust-obscured and unobscured samples based on their optical to mid-IR color, and measure the neutral hydrogen column density N_H through fitting of the X-ray spectra. We find that all subsets of quasars have consistent power law photon indices equal to 1.9 that are uncorrelated with N_H. We classify the quasars as gas-absorbed or gas-unabsorbed if N_H > 10^22 cm^-2 or N_H < 10^22 cm^-2, respectively. Of 24 dust-unobscured quasars in the sample, only one shows clear evidence for significant intrinsic N_H, while 22 have column densities consistent with N_H < 10^22 cm^-2. In contrast, of the nine dust-obscured quasars, six show evidence for intrinsic gas absorption, and three are consistent with N_H < 10^22 cm^-2. We conclude that dust extinction in IR-selected quasars is strongly correlated with significant gas absorption as determined through X-ray spectral fitting. These results suggest that obscuring gas and dust in quasars are generally co-spatial, and confirm the reliability of simple mid-IR and optical photometric techniques for separating quasars based on obscuration.

Long-Term Monitoring Of Hα Emission Strength And Photometric V Magnitude Of Γ Cas, E. Pollmann, W. Vollmann, Gregory W. Henry

Information Systems and Engineering Management Research Publications

No abstract provided.

Test Of Models Of The Cosmic Infrared Background With Multiwavelength Observations Of The Blazar 1es 1218+30.4 In 2009, P. T. Reynolds

Physical Sciences Publications

We present the results of a multi-wavelength campaign targeting the blazar 1ES 1218+30.4 with observations with the 1.3 m McGraw-Hill optical telescope, the Rossi X-ray Timing Explorer (RXTE), the Fermi Gamma-Ray Space Telescope, and the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The RXTE and VERITAS observations were spread over a 13 day period and revealed clear evidence for flux variability, and a strong X-ray and γ-ray flare on 2009 February 26 (MJD 54888). The campaign delivered a well-sampled broadband energy spectrum with simultaneous RXTE and VERITAS very high energy (VHE, >100 GeV) observations, as well as …

Type Ia Supernova Rate Measurements To Redshift 2.5 From Candels: Searching For Prompt Explosions In The Early Universe, Steven A. Rodney, Adam G. Riess, Louis-Gregory Strolger, Tomas Dahlen, Or Graur, Stefano Casertano, Mark E. Dickinson, Henry C. Ferguson, Peter Garnavich, Brian Hayden, Saurabh W. Jha, David O. Jones, Robert P. Kirshner, Anton M. Koekemoer, Curtis Mccully, Bahram Mobasher, Brandon Patel, Benjamin J. Weiner, S. Bradley Cenko, Kelsey I. Clubb, Michael Cooper, Alexei V. Filippenko, Teddy F. Frederiksen, Jens Hjorth, Bruno Leibundgut, Thomas Matheson, Hooshang Nayyeri, Kyle Penner, Jonathan Trump, Jeffrey M. Silverman, Vivian U, K. Azalee Bostroem, Peter Challis, Abhijith Rajan, Schuyler Wolff, S. M. Faber, Norman A. Grogin, Dale D. Kocevski

Physics and Astronomy Faculty Publications

The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope (HST) that surveyed a total area of ~0.25 deg² with ~900 HST orbits spread across five fields over three years. . . .

For the remainder of the abstract, please visit:

http://dx.doi.org/10.1088/0004-6256/148/1/13

The Angular Clustering Of Infrared-Selected Obscured And Unobscured Quasars, M. A. Dipompeo, A. D. Myers, R. C. Hickox, J. E. Geach, K. N. Hainline

Dartmouth Scholarship

Recent studies of luminous infrared-selected active galactic nuclei (AGN) suggest that the reddest, most obscured objects display a higher angular clustering amplitude, and thus reside in higher-mass dark matter halos. This is a direct contradiction to the prediction of the simplest unification-by-orientation models of AGN and quasars. However, clustering measurements depend strongly on the "mask" that removes low-quality data and describes the sky and selection function. We find that applying a robust, conservative mask to WISE-selected quasars yields a weaker but still significant difference in the bias between obscured and unobscured quasars. These findings are consistent with results from previous …

Discovery Of X-Ray Pulsations From A Massive Star., Lidia Oskinova, Yael Nazé, Helge Todt, David Huenemoerder, Richard Ignace, Swetlana Hubrig, Wolf-Rainer Hamann

ETSU Faculty Works

X-ray emission from stars much more massive than the Sun was discovered only 35 years ago. Such stars drive fast stellar winds where shocks can develop, and it is commonly assumed that the X-rays emerge from the shock-heated plasma. Many massive stars additionally pulsate. However, hitherto it was neither theoretically predicted nor observed that these pulsations would affect their X-ray emission. All X-ray pulsars known so far are associated with degenerate objects, either neutron stars or white dwarfs. Here we report the discovery of pulsating X-rays from a non-degenerate object, the massive B-type star ξ1 CMa. This star is a …

The Evolution Of And Starburst-Agn Connection In Luminous And Ultraluminous Infrared Galaxies And Their Link To Globular Cluster Formation, Stephanie L. Fiorenza

Dissertations, Theses, and Capstone Projects

The evolutionary connection between nuclear starbursts and active galactic nuclei (AGN) in luminous infrared galaxies (LIRGs; 1011o

Using new spectrophotometric data, I classify the primary source of IR radiation as being a nuclear starburst or a type of AGN by using the Baldwin-Phillips-Terlevich (BPT) diagrams. I show that for the U/LIRGs in my sample the properties that describe their nuclear starbursts and AGN (e.g. star formation rate (SFR), L[O III], optical D parameter, D4000, and EW(Hδ)) are independent of one another, ensuring that no biases affect correlations between these properties and objects' locations on the BPT diagrams. I then derive …

Linked-Cluster Expansion For The Green's Function Of The Infinite-U Hubbard Model, Ehsan Khatami, Edward Perepelitsky, Marcos Rigol, Sriram B. Shastry

Faculty Publications

We implement a highly efficient strong-coupling expansion for the Green's function of the Hubbard model. In the limit of extreme correlations, where the onsite interaction is infinite, the evaluation of diagrams simplifies dramatically enabling us to carry out the expansion to the eighth order in powers of the hopping amplitude. We compute the finite-temperature Green's function analytically in the momentum and Matsubara frequency space as a function of the electron density. Employing Padé approximations, we study the equation of state, Kelvin thermopower, momentum distribution function, quasiparticle fraction, and quasiparticle lifetime of the system at temperatures lower than, or of the …

The Energetic Particle Detector (Epd) Investigation And The Energetic Ion Spectrometer (Eis) For The Magnetospheric Multiscale (Mms) Mission, B. H. Mauk, J. B. Blake, D. N. Baker, J. H. Clemmons, Geoffrey Reeves, Harlan E. Spence, S. E. Jaskulek, C. E. Schlemm, L. E. Brown, Steve Cooper, J. V. Craft, J. F. Fennell, R. S. Gurnee, C. M. Hammock, J. R. Hayes, P. A. Hill, G. C. Ho, J. C. Hutcheson, A. D. Jacques, S. Kerem, D. G. Mitchell, K. S. Nelson, N. P. Paschalidis, E. Rossano, M. R. Stokes, J. H. Westlake

Space Science Center

Abstract

The Energetic Particle Detector (EPD) Investigation is one of 5 fields-and-particles investigations on the Magnetospheric Multiscale (MMS) mission. MMS comprises 4 spacecraft flying in close formation in highly elliptical, near-Earth-equatorial orbits targeting understanding of the fundamental physics of the important physical process called magnetic reconnection using Earth’s magnetosphere as a plasma laboratory. EPD comprises two sensor types, the Energetic Ion Spectrometer (EIS) with one instrument on each of the 4 spacecraft, and the Fly’s Eye Energetic Particle Spectrometer (FEEPS) with 2 instruments on each of the 4 spacecraft. EIS measures energetic ion energy, angle and elemental compositional distributions from …

Application Of An Isogeometric Boundary Element Method To The Calculation Of Acoustic Radiation Modes And Their Efficiencies, Candice Marie Humpherys

Theses and Dissertations

In contrast to the structural modes, which describe the physical motion of vibrating structures, acoustic radiation modes describe the radiated sound power. Radiation modes are beneficial in active noise control because reducing an efficiently radiating radiation mode guarantees the reduction of radiated sound power. Much work has been done to calculate the radiation modes for simple geometries, where analytic solutions are available. In this work, isogeometric analysis (IGA) is used to provide a tool capable of analyzing the radiation modes of arbitrarily complex geometries. IGA offers increased accuracy and efficiency by using basis functions generated from Non-Uniform Rational B-Splines (NURBS) …

The Ninja-2 Project: Detecting And Characterizing Gravitational Waveforms Modelled Using Numerical Binary Black Hole Simulations, J. Aasi, B. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, T. Accadia, Mario C. Diaz, Malik Rakhmanov, Joseph D. Romano, Soma Mukherjee, Volker Quetschke, Teviet Creighton, Robert Stone

Physics & Astronomy Faculty Publications

The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational-wave (GW) astrophysics communities. The purpose of NINJA is to study the ability to detect GWs emitted from merging binary black holes (BBH) and recover their parameters with next-generation GW observatories. We report here on the results of the second NINJA project, NINJA-2, which employs 60 complete BBH hybrid waveforms consisting of a numerical portion modelling the late inspiral, merger, and ringdown stitched to a post-Newtonian portion modelling the early inspiral. In a ‘blind injection challenge’ similar to that conducted in recent Laser …

The White Dwarfs Within 25 Pc Of The Sun: Kinematics And Spectroscopic Subtypes, Edward M. Sion, Jay B. Holberg, Terry D. Oswalt, George P. Mccook, Richard Wasatonic, Janine Myszka

Aerospace, Physics, and Space Science Faculty Publications

We present the fractional distribution of spectroscopic subtypes, range and distribution of surface temperatures, and kinematical properties of the white dwarfs (WDs) within 25 pc of the Sun. There is no convincing evidence of halo WDs in the total 25 pc sample of 224 WDs. There is also little to suggest the presence of genuine thick disk subcomponent members within 25 pc. It appears that the entire 25 pc sample likely belongs to the thin disk. We also find no significant kinematic differences with respect to spectroscopic subtypes. The total DA to non-DA ratio of the 25 pc sample is …

The Baryonic Tully-Fisher Relationship For S4g Galaxies And The "Condensed" Baryon Fraction Of Galaxies, Dennis Zaritsky, Trisha F. Mizusawa

Aerospace, Physics, and Space Science Faculty Publications

We combine data from the Spitzer Survey for Stellar Structure in Galaxies, a recently calibrated empirical stellar mass estimator from Eskew et al., and an extensive database of H I spectral line profiles to examine the baryonic Tully-Fisher (BTF) relation. We find (1) that the BTF has lower scatter than the classic Tully-Fisher (TF) relation and is better described as a linear relationship, confirming similar previous results, (2) that the inclusion of a radial scale in the BTF decreases the scatter but only modestly, as seen previously for the TF relation, and (3) that the slope of the BTF, which …

Radiative Cooling Ii: Effects Of Density And Metallicity, Ye Wang, Gary J. Ferland, Matt Lykins, R. L. Porter, Peter A. M. Van Hoof, R. J. R. Williams

Physics and Astronomy Faculty Publications

This work follows Lykins et al. discussion of classic plasma cooling function at low density and solar metallicity. Here, we focus on how the cooling function changes over a wide range of density (n_H <10¹² cm⁻³) and metallicity (Z < 30 Z_⊙). We find that high densities enhance the ionization of elements such as hydrogen and helium until they reach local thermodynamic equilibrium. By charge transfer, the metallicity changes the ionization of hydrogen when it is partially ionized. We describe the total cooling function as a sum of four parts: those due to H&He, the heavy …

Milky Way Red Dwarfs In The Borg Survey : Galactic Scale-Height And The Distribution Of Dwarf Stars In Wfc3 Imaging., Benne W. Holwerda, M. Trenti, W. Clarkson, K. Sahu, L. Bradley, M. Stiavelli, N. Pirzkal, G. De Marchi, M. Andersen, R. J. Bouwens, R. Ryan

Faculty and Staff Scholarship

We present a tally of Milky Way late-type dwarf stars in 68 Wide Field Camera 3 (WFC3) pure-parallel fields (227 arcmin2) from the Brightest of Reionizing Galaxies survey for high-redshift galaxies. Using spectroscopically identified M-dwarfs in two public surveys, the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey and the Early Release Science mosaics, we identify a morphological selection criterion using the half-light radius (r50), a near-infrared J − H, G − J color region where M-dwarfs are found, and a V − J relation with M-dwarf subtype. We apply this morphological selection of stellar objects, color–color selection of M-dwarfs, and …

Arecibo Pulsar Survey Using Alfa. Iii. Precursor Survey And Population Synthesis, J. K. Swiggum, D. R. Lorimer, M. A. Mclaughlin, S. D. Bates, D. J. Champion, S. M. Ransom, A. Brazier, J. W.T. Hessels, D. J. Nice, Fredrick A. Jenet

Physics & Astronomy Faculty Publications

The Pulsar Arecibo L-band Feed Array (PALFA) Survey uses the ALFA 7-beam receiver to search both inner and outer Galactic sectors visible from Arecibo (32° ≲ ℓ ≲ 77° and 168° ≲ ℓ ≲ 214°) close to the Galactic plane (|b| ≲ 5°) for pulsars. The PALFA survey is sensitive to sources fainter and more distant than have previously been seen because of Arecibo's unrivaled sensitivity. In this paper we detail a precursor survey of this region with PALFA, which observed a subset of the full region (slightly more restrictive in ℓ and |b| ≲ 1°) …

Reconstructing The Stellar Mass Distributions Of Galaxies Using S4g Irac 3.6 And 4.5 Μm Images. Ii. The Conversion From Light To Mass., Sharon Meidt, Eva Schinnerer, Glenn Van De Ven, Dennis Zaritsky, Reynier Peletier, Johan H. Knapen, Kartik Sheth, Michael Regan, Miguel Querejeta, Juan Carlos Munoz-Mateos, Taehyun Kim, Joannah Hinz, Armando Gil De Paz, E. Athanassoula, Albert Bosma, Ronald J. Buta, Mauricio Cisternas, Luis C. Ho, Benne W. Holwerda, Ramin Skibba, E. Laurikainen, H. Salo, D. A. Gadotti, Jarkko Laine, Santiago Erroz-Ferrer, Sebastien Comeron, K. Menendez-Delmestre, M. Seibert, T. Mizusawa

Faculty and Staff Scholarship

We present a new approach for estimating the 3.6μm stellar mass-to-light (M/L) ratio ϒ3.6 in terms of the [3.6]–[4.5] colors of old stellar populations. Our approach avoids several of the largest sources of uncertainty in existing techniques using population synthesis models. By focusing on mid-IR wavelengths, we gain a virtually dust extinction-free tracer of the old stars, avoiding the need to adopt a dust model to correctly interpret optical or optical/near-IR colors normally leveraged to assign the mass-to-light ratio ϒ. By calibrating a new relation between near-IR and mid-IR colors of giant stars observed in GLIMPSE we also avoid the …

The Baryonic Tully-Fisher Relationship For S4g Galaxies And The "Condensed" Baryon Fraction Of Galaxies., Dennis Zaritsky, Helene M. Courtois, Juan Carlos Munoz-Mateos, Jenny Sorce, S. Erroz-Ferrer, S. Comeron, D. A. Gadotti, A. Gil De Paz, J. L. Hinz, E. Laurikainen, T. Kim, J. Laine, K. Menendez-Delmestre, T. Mizusawa, M. W. Regan, H. Salo, M. Seibert, K. Sheth, E. Athanassoula, A. Bosma, M. Cisternas, Luis C. Ho, Benne W. Holwerda

Faculty and Staff Scholarship

We combine data from the Spitzer Survey for Stellar Structure in Galaxies, a recently calibrated empirical stellar mass estimator from Eskew et al., and an extensive database of H i spectral line profiles to examine the baryonic Tully–Fisher (BTF) relation. We find (1) that the BTF has lower scatter than the classic Tully–Fisher (TF) relation and is better described as a linear relationship, confirming similar previous results, (2) that the inclusion of a radial scale in the BTF decreases the scatter but only modestly, as seen previously for the TF relation, and (3) that the slope of the BTF, which …