Astrophysics and Astronomy Commons^™

The Swift/Fermi Grb 080928 From 1 Ev To 150 Kev, A. Rossi, S. Schulze, S. Klose, D. A. Kann, A. Rau, H. A. Krimm, G. Jóhannesson, A. Panaitescu, F. Yuan, P. Ferrero, T. Krühler, J. Greiner, P. Schady, S. B. Pandey, L. Amati, P. M.J. Afonso, C. W. Akerlof, L. A. Arnold, C. Clemens, R. Filgas, D. H. Hartmann, A. Küpcü Yoldas, S. Mcbreen, T. A. Mckay, A. Nicuesa Guelbenzu, F. E. Olivares, B. Paciesas, E. S. Rykoff, G. Szokoly, Adria Updike, A. Yoldas

Arts & Sciences Faculty Publications

We present the results of a comprehensive study of the gamma-ray burst 080928 and of its afterglow. GRB 080928 was a long burst detected by Swift/BAT and Fermi/GBM. It is one of the exceptional cases where optical emission had already been detected when the GRB itself was still radiating in the gamma-ray band. For nearly 100 s simultaneous optical, X-ray and gamma-ray data provide a coverage of the spectral energy distribution of the transient source from about 1 eV to 150 keV. In particular, we show that the SED during the main prompt emission phase agrees with synchrotron radiation.We constructed …

Early Magnetic B-Type Stars: X-Ray Emission And Wind Properties, Lidia Oskinova, Helge Todt, Richard Ignace, John Brown, Joseph Cassinelli, Wolf-Rainer Hamann

ETSU Faculty Works

We present a comprehensive study of X-ray emission and wind properties of magnetic early B-type stars. We compile the complete sample of early B-type stars with detected magnetic fields to date and existing X-ray measurements, in order to study whether the X-ray emission can be used as a general proxy for stellar magnetism. For the first time we analyze the UV spectra of B stars with magnetic fields by means of non-LTE iron-blanketed stellar atmosphere model that account for the X-rays at the intensity and temperatures observed. The mass-loss rates inferred from the analysis of UV lines are significantly lower …

The Energy Source Of The Filaments Around The Giant Galaxy Ngc 1275, A. C. Fabian, J. S. Sanders, R. J. R. Williams, A. Lazarian, Gary J. Ferland, R. M. Johnstone

Physics and Astronomy Faculty Publications

The brightest galaxy in the nearby Perseus cluster, NGC 1275, is surrounded by a network of filaments. These were first observed through their Hα emission but are now known to have a large molecular component with a total mass approaching 10¹¹ M_⊙ of gas. The filaments are embedded in hot intracluster gas and stretch over 80 kpc. They have an unusually low excitation spectrum which is well modelled by collisional heating and ionization by secondary electrons. Here we note that the surface radiative flux from the outer filaments is close to the energy flux impacting on them from …

Herschel Observations Of The Centaurus Oluster - The Dynamics Of Cold Gas In A Cool Core, R. Mittal, C. P. O'Dea, Gary J. Ferland, J. B. R. Oonk, A. C. Edge, R. E. A. Canning, H. Russell, S. A. Baum, H. Böhringer, F. Combes, M. Donahue, A. C. Fabian, N. A. Hatch, A. Hoffer, R. Johnstone, B. R. Mcnamara, P. Salomé, G. Tremblay

Physics and Astronomy Faculty Publications

Brightest cluster galaxies (BCGs) in the cores of galaxy clusters have distinctly different properties from other low-redshift massive ellipticals. The majority of the BCGs in cool-core clusters show signs of active star formation. We present observations of NGC 4696, the BCG of the Centaurus galaxy cluster, at far-infrared (FIR) wavelengths with theHerschel space telescope. Using the PACS spectrometer, we detect the two strongest coolants of the interstellar medium, [C II] at 157.74 μm and [O I] at 63.18 μm, and in addition [N II] at 121.90 μm. The [C II] emission is extended over a region of 7 kpc …

A Deep Spectroscopic Study Of The Filamentary Nebulosity In Ngc 4696, The Brightest Cluster Galaxy In The Centaurus Cluster, R. E. A. Canning, A. C. Fabian, R. M. Johnstone, J. S. Sanders, C. S. Crawford, Gary J. Ferland, N. A. Hatch

Physics and Astronomy Faculty Publications

We present results of deep integral-field spectroscopy observations using high-resolution optical (4150–7200 Å) VLT VIsible MultiObject Spectrograph spectra of NGC 4696, the dominant galaxy in the Centaurus cluster (Abell 3526). After the Virgo cluster, this is the second nearest (z= 0.0104) example of a cool-core cluster. NGC 4696 is surrounded by a vast, luminous Hα emission-line nebula (L_Hα= 2.2 × 10⁴⁰ erg s⁻¹). We explore the origin and excitation of the emission-line filaments and find their origin consistent with being drawn out, under rising radio bubbles, into the intracluster medium as in …

Monster In The Dark: The Ultraluminous Grb 080607 And Its Dusty Environment, D.A. Perley, A.N. Morgan, Adria Updike, F. Yuan, C.W. Akerlof, A.A. Miller, J.S. Bloom, S.B. Cenko, W. Li, A.V. Filippenko, J.X. Prochaska, D.A. Kann, N.R. Tanvir, A.J. Levan, N.R. Butler, P. Christian, D.H. Hartmann, P. Milne, E.S. Rykoff, W. Rujopakarn, J.C. Wheeler, G.G. Williams

Arts & Sciences Faculty Publications

We present early-time optical through infrared photometry of the bright Swift gamma-ray burst (GRB) 080607, starting only 6 s following the initial trigger in the rest frame. Complemented by our previously published spectroscopy, this high-quality photometric data set allows us to solve for the extinction properties of the redshift 3.036 sightline, giving perhaps the most detailed information to date on the ultraviolet continuum absorption properties of any sightline outside our Local Group. The extinction properties are not adequately modeled by any ordinary extinction template (including the average Milky Way, Large Magellanic Cloud, and Small Magellanic Cloud curves), partially because the …

Grb 090426: Discovery Of A Jet Break In A Short Burst Afterglow, A. Nicuesa Guelbenzu, S. Klose, A. Rossi, D.A. Kann, T. Krühler, J. Greiner, A. Rau, F. Olivares E., P.M.J. Afonso, R. Filgas, A. Küpcü Yoldas, S. Mcbreen, M. Nardini, P. Schady, S. Schmidl, Adria Updike, A. Yoldas

Arts & Sciences Faculty Publications

Context. The link between the duration of GRBs and the nature of their progenitors remains disputed. Short bursts (with durations of less than ∼2 s) are less frequently observed, technically more difficult to localize, and exhibit significantly fainter afterglows. Aims. It is of critical importance to establish whether the burst duration can reliably distinguish the different GRB population models of collapsars and compact stellar mergers. The Swift GRB 090426 provides an unique opportunity to address this question. Its duration (T90 = 1.28 s) places GRB 090426 firmly in the short burst population, while the high redshift (z = 2.609), host …

The Study Of Variability In Four Oxygen-Rich Proto-Planetary Nebulae, Kristie Shaw

Symposium on Research and Creative Expression (SORCE)

This summer, I have been working on a project to study the variability of four proto-planetary nebulae. Proto-planetary nebulae (PPNe) are evolved stellar objects that are in the process of losing their outer layers and in transition from a red giant star to a planetary nebula. Oxygen-rich PPNe, specifically, have a higher oxygen content in their nebula than they do carbon, and this occurs mainly in lower mass stars. This project includes combining our data from the VU Observatory with other published data, analyzing light curves of brightness versus time and looking for patterns, and performing period analysis using a …

Mount Graham, Janet Butler Munch

Publications and Research

Mount Graham, in southern Arizona, is considered a sacred location by the Apaches. The remoteness and high elevation of the mountain makes it an ideal location for astronomical research. After protracted litigation suits, the University of Arizona prevailed and was allowed to establish the Mount Graham International Observatory on the site.

The Vlt Lbg Redshift Survey- Ii. Interactions Between Galaxies And The Igm At Z ~ 3, N. H.M. Crighton, R. Bielby, T. Shanks, L. Infante, C. G. Bornancini, N. Bouché, D. G. Lambas, James D. Lowenthal, D. Minniti, S. L. Morris, N. Padilla, C. Péroux, P. Petitjean, T. Theuns, P. Tummuangpak, P. M. Weilbacher, L. Wisotzki, G. Worseck

Astronomy: Faculty Publications

We have measured redshifts for 243 z≈ 3 quasars in nine Very Large Telescope (VLT) Visible Imaging and Multi-Object Spectrograph (VIMOS) Lyman-break galaxy (LBG) redshift survey areas, each of which is centred on a known bright quasar. Using the spectra of these quasars, we measure the cross-correlation between neutral hydrogen gas causing the Lyα forest and 1020 LBGs at z≈ 3. We find an increase in neutral hydrogen absorption within ≈5h Mpc of a galaxy in agreement with the results of Adelberger et al. The Lyα-LBG cross-correlation can be described by a power law on scales larger than 3h Mpc. …

Observational Studies Of Proto-Planetary Nebulae At The Valparaiso University Observatory, Christopher Miko, Rachael Jensema

Symposium on Research and Creative Expression (SORCE)

We are observing the light variation with time of a sample of 26 proto-planetary nebulae (PPNe) using Valparaiso University’s 16-inch computer-controlled reflector telescope and CCD digital camera. PPNe are evolved stars late in their lifetime, in between the red giant and planetary nebula phase. The resulting images are analyzed and properly calibrated to produce quantitative measurements of light intensity with respect to time. We are particularly analyzing nine PPNe and their light variations through time to quantify variability and search for periods to their variability. Of the nine, all are variable over a range of 10-50%. Five demonstrate an approximate …

Searching For Binary Stars In Planetary Nebulae Using The Isis Image Subtraction Software, Samantha Schwartz

Symposium on Research and Creative Expression (SORCE)

We explored the theory that binary central stars of planetary nebulae may be contributing factor in the formation of planetary nebulae. We searched for this photometric variability in central stars of planetary nebulae because consistent periodic variability is indicative of a close binary system. The variability of our targets was assessed with the image subtraction software, ISIS. We found that the central stars of the planetary nebulae Hen 2-84, NGC 6326, and K 1-22 showed clear variability. A preliminary light curve for Hen 2-84 showed periodic behavior, suggesting a binary system. Of the remaining targets observed, with sufficient data, five …

Calibrating The Star Endcap Electromagnetic Calorimeter Using π-0'S, Benjamin Barber

Symposium on Research and Creative Expression (SORCE)

The STAR Endcap ElectroMagnetic Calorimeter (EEMC) is an important tool for identifying the particles produced in the forward direction of the STAR detector. These particles are used in the study of the proton's intrinsic angular momentum. Current calibrations of the EEMC have relied on the energy deposition of minimally ionizing particles (MIPs). To verify the MIP-based calibration, we are re-calibrating it using the energy deposition of the di-photon pairs created by Ï€-0 decays. Using the position and initial energy calibration of the two photon events, we can reconstruct the invariant mass of the parent particle. When this analysis is performed …

Initial Studies Of The Forward Gem Tracker, Malorie Stowe, David Grosnik

Symposium on Research and Creative Expression (SORCE)

The spin of the proton is known to be produced by several constituents including quarks, antiquarks, and gluons. It has been the goal of STAR to measure the contribution of gluons and various sea quarks to the proton spin. The Forward GEM Tracker (FGT) is a newly constructed detector to be placed into STAR, which is located at the RHIC collider at Brookhaven National Laboratory. The FGT serves to track the position of forward going charged particles, produced in proton-proton collisions, as they travel towards the Endcap Electromagnetic Calorimeter (EEMC). This information will be critical in helping to determine the …

Radon Concentration In Basements, Joel Rogers

Symposium on Research and Creative Expression (SORCE)

This summer I am studying radon gas concentrations in basements in the Valparaiso community area. Radon is known to be the second leading cause of lung cancer after smoking. After several years (more than twenty) of continuous radon inhalation, the human lungs can be impaired and can become cancerous. This study will help people be aware of a potential radon problem in their homes. The EPA recommends having a concentration of four picocuries per liter or less in each home. The experiment is performed by using an EPA approved radon testing apparatus that records the concentration each hour for up …

A Mip-Based Energy Calibration Of The Star Endcap Electromagnetic Calorimeter, Zachary Nault

Symposium on Research and Creative Expression (SORCE)

One of the main goals of the STAR Spin Collaboration is to understand the intrinsic angular momentum of the proton. An integral part of this experiment is the Endcap Electromagnetic Calorimeter (EEMC). The EEMC is used in detecting particles produced from hard proton-proton collisions that end up in the forward direction or 'end' of the experimental apparatus. In order to use properly the data collected, the energy and position measurements in the EEMC need to be well-known. To accomplish this, an energy calibration of the EEMC was performed using minimum ionizing particles (MIPs). The important property of MIPs utilized was …

Verification Of Monte-Carlo Simulation For Star Endcap Electromagnetic Calorimeter, Kevin Miller

Symposium on Research and Creative Expression (SORCE)

The STAR experiment at Brookhaven National Laboratory seeks to measure the source of the protons spin, a fundamental property of matter. To accomplish this measurement, a simulation method called Monte-Carlo will be used to model the true detector responses to proton-proton collisions. My work is to confirm the accuracy of the Monte-Carlo simulation for the Endcap Electromagnetic Calorimeter (EEMC). By comparing histograms of fundamental parameters from the Monte-Carlo simulated data and true data from 2006 experimentation, we will be able to test the simulations accuracy. When validated, the Monte-Carlo simulation will be used to achieve a greater understanding of the …

The Reduction And Reporting Of Data On Proto-Planetary Nebulae From Two Observatories, Wesley Cheek

Symposium on Research and Creative Expression (SORCE)

I am documenting the light variability in a sample of proto-planetary nebulae (PPNs) observed from two observatories. PPNs are stars in the stage of evolution between the AGB and planetary nebula phases. I analyzed the digital images of the data taken on 34 nights from the SARA-South observatory located in Cerro Tololo, Chile along with data taken from the SARA-North Observatory located in Tuscon, Arizona. This was done to obtain quantitative measurements of the brightness variations over time. Once I had this information for each object, I plotted light curves, which can be used to document the amplitudes and possible …

On The Clustering Of Sub-Millimeter Galaxies, Christina Williams, Mauro Giavalisco, Cristiano Porciani, Min Yun, Alexandra Pope, Kimberly Scott, Jason Austermann, Itziar Aretxaga, Bunyo Hatsukade, Kyoung-Soo Lee, Grant Wilson, J. Ryan Cybulski, David Hughes, Ryo Kawabe, Kotaro Kohno, Thushara Perera, F. Peter Schloerb

Scholarship

We measure the angular two-point correlation function of sub-millimeter galaxies (SMGs) from 1.1-millimeter imaging of the COSMOS field with the AzTEC camera and ASTE 10-meter telescope. These data yields one of the largest contiguous samples of SMGs to date, covering an area of 0.72 degrees^2 down to a 1.26 mJy/beam (1-sigma) limit, including 189 (328) sources with S/N greater than 3.5 (3). We can only set upper limits to the correlation length r_0, modeling the correlation function as a power-law with pre-assigned slope. Assuming existing redshift distributions, we derive 68.3% confidence level upper limits of r_0 < 6-8 h^-1 Mpc at 3.7 mJy, and r_0 < 11-12 h^-1 Mpc at 4.2 mJy. Although consistent with most previous estimates, these upper limits imply that the real r_0 is likely smaller. This casts doubts on the robustness of claims that SMGs are characterized by significantly stronger spatial clustering, (and thus larger mass), than differently selected galaxies at high-redshift. Using Monte Carlo simulations we show that even strongly clustered distributions of galaxies can appear unclustered when sampled with limited sensitivity and coarse angular resolution common to current sub-millimeter surveys. The simulations, however, also show that unclustered distributions can appear strongly clustered under these circumstances. From the simulations, we predict that at our survey depth, a mapped area of two degrees^2 is needed to reconstruct the correlation function, assuming smaller beam sizes of future surveys (e.g. the Large Millimeter Telescope's 6" beam size). At present, robust measures of the clustering strength of bright SMGs appear to be below the reach of most observations.

High-Order Finite Difference Methods With Subcell Resolution For 2d Detonation Waves, W. Wang, C.-W. Shu, Helen Yee, Bjorn Sjögreen

United States National Aeronautics and Space Administration: Publications

In simulating hyperbolic conservation laws in conjunction with an inhomogeneous stiff source term, if the solution is discontinuous, spurious numerical results may be produced due to the different time scales of the transport part and the source term. This numerical issue often arises in combustion and high-speed chemical reacting flows.

Our objective in this study is to extend this method to two-dimensional reactive Euler equations. The first step of the proposed fractional step method is the convection step which solves the homogeneous hyperbolic conservation law in which any high-resolution shock-capturing method can be used. The aim in this step is …