Astrophysics and Astronomy Commons^™

A New Activity Phase Of The Blazar 3c 454.3 Multifrequency Observations By The Webt And Xmm-Newton In 2007-2008, Niall Smith, Et. Al.

Blackrock Castle Observatory Publications

Aims: The Whole Earth Blazar Telescope (WEBT) consortium has been monitoring the blazar 3C 454.3 from the radio to the optical bands since 2004 to study its emission variability properties.

Methods: We present and analyse the multifrequency results of the 2007-2008 observing season, including XMM-Newton observations and near-IR spectroscopic monitoring, and compare the recent emission behaviour with the past one. The historical mm light curve is presented here for the first time.

Results: In the optical band we observed a multi-peak outburst in July-August 2007, and other faster events in November 2007-February 2008. During these outburst phases, several episodes of …

Poet: Polarimeters For Energetic Transients, J. E. Hill, M. L. Mcconnell, P. Bloser, J. Legere, J. Macri, J. Ryan, S. Barthelmy, L. Angelini, T. Sakamoto, J K. Black, Dieter H. Hartmann, P Kaaret, B Zhang, K Ioka, T Nakamura, K Toma, R Yamazaki, X Wu

Publications

POET (Polarimeters for Energetic Transients) is a Small Explorer mission concept proposed to NASA in January 2008. The principal scientific goal of POET is to measure GRB polarization between 2 and 500 keV. The payload consists of two wide FoV instruments: a Low Energy Polarimeter (LEP) capable of polarization measurements in the energy range from 2-15 keV and a high energy polarimeter (Gamma-Ray Polarimeter Experiment – GRAPE) that will measure polarization in the 60-500 keV energy range. Spectra will be measured from 2 keV up to 1 MeV. The POET spacecraft provides a zenith-pointed platform for maximizing the exposure to …

Forming Early-Type Galaxies In Groups Prior To Cluster Assembly, Stefan Kautsch, Anthony H. Gonzalez, Christian A. Soto, Kim-Vy H. Tran, Dennis Zaritsky, John Moustakas

Chemistry and Physics Faculty Articles

We study a unique protocluster of galaxies, the supergroup SG1120–1202. We quantify the degree to which morphological transformation of cluster galaxies occurs prior to cluster assembly in order to explain the observed early-type fractions in galaxy clusters at z = 0. SG1120–1202 at z ~ 0.37 is composed of four gravitationally bound groups that are expected to coalesce into a single cluster by z = 0. Using HST ACS observations, we compare the morphological fractions of the supergroup galaxies to those found in a range of environments. We find that the morphological fractions of early-type galaxies (~60%) and the ratio …

Parallax And Distance Estimates For Twelve Cataclysmic Variable Stars, John R. Thorstensen, Sébastien Lépine, Michael Shara

Dartmouth Scholarship

We report parallax and distance estimates for 12 more cataclysmic binaries and related objects observed with the 2.4 m Hiltner telescope at MDM Observatory. The final parallax accuracy is typically ~1 mas. Notable results include distances for V396 Hya (CE 315), a helium double degenerate with a relatively long orbital period, and for MQ Dra (SDSSJ155331+551615), a magnetic system with a very low accretion rate. We find that the Z Cam star KT Persei is physically paired with a K main-sequence star lying 15 arcsec away. Several of the targets have distance estimates in the literature that are based on …

A Novel Method For Measuring The Extragalactic Background Light: Fermi Application To The Lobes Of Fornax A, Markos Georganopoulos, Rita M. Sambruna, Demosthenes Kazanas, Analia N. Cillis, Chi C. Cheung, Eric S. Perlman, Katherine M. Blundell, David S. Davis

Aerospace, Physics, and Space Science Faculty Publications

We describe a new method for measuring the extragalactic background light (EBL) through the detection of γ-ray inverse Compton (IC) emission due to scattering of the EBL photons off relativistic electrons in the lobes of radio galaxies. Our method has no free physical parameters and is a powerful tool when the lobes are characterized by a high-energy sharp break or cutoff in their electron energy distribution (EED). We show that such a feature will produce a high-energy IC “imprint” of the EBL spectrum in which the radio lobes are embedded and show how this imprint can be used to derive …

On The Importance Of The Interclump Medium For Superionization: O Vi Formation In The Wind Of Zeta Puppis, J. Zsargó, D. J. Hillier, J.-C. Bouret, T. Lanz, M. A. Leutenegger, David H. Cohen

Physics & Astronomy Faculty Works

We have studied superionization and X-ray line formation in the spectra of zeta Pup using our new stellar atmosphere code (XCMFGEN) that can be used to simultaneously analyze optical, UV, and X-ray observations. Here, we present results on the formation of the O VI lambda lambda 1032, 1038 doublet. Our simulations, supported by simple theoretical calculations, show that clumped wind models that assume void in the interclump space cannot reproduce the observed O vi profiles. However, enough O vi can be produced if the voids are filled by a low-density gas. The recombination of O vi is very efficient in …

Neutrino-Nucleus Reaction Cross Sections For Light Element Systhesis In Supernova Explosions, Takashi Yoshida, Toshio Suzuki, Satoshi Chiba, Toshitaka Kajino, Hidekazu Yokomakura, Keiichi Kimura, Akira Takamura, Dieter H. Hartmann

Publications

The neutrino-nucleus reaction cross sections of 4He and 12C are evaluated using new shell model Hamiltoni-ans. Branching ratios of various decay channels are calculated to evaluate the yields of Li, Be, and B producedthrough the ν -process in supernova explosions. The new cross sections enhance the yields of7Li and11B pro-duced during the supernova explosion of a 16.2 M⊙star model compared to the case using the conventionalcross sections by about 10%. On the other hand, the yield of10B decreases by a factor of two. The yieldsof6Li,9Be, and the radioactive nucleus10 Be are found at a level of ∼ 10−11M⊙. The temperature …

A Photometric Redshift Of Z = 1.8{+0.4}{-0.3} For The Agile Grb 080514b, A. Rossi, A. De Ugarte Postigo, P. Ferrero, D. A. Kann, S. Klose, S. Schulze, J. Greiner, P. Schady, R. Filgas, E E. Gonsalves, A Küpcü Yoldaş, T Krühler, G Szokoly, A Yoldas, P.M.J. Afonso, C Clemens, J S. Bloom, D A. Perley, J.P.U. Fynbo, A J. Castro-Tirado, J Gorosabel, P Kubanek, A C. Updike, Dieter H. Hartmann, A Giuliani, S T. Holland, L Hanlon, M Bremer, J French, G Melady, D A. Garcia-Hernandez

Publications

The AGILE gamma-ray burst GRB 080514B is the first detected to have emission above 30 MeV and an optical afterglow. However, no spectroscopic redshift for this burst is known. We report on our ground-based optical/NIR and millimeter follow-up observations of this event at several observatories, including the multi-channel imager GROND on La Silla, supplemented by Swift UVOT and Swift XRT data. The spectral energy distribution (SED) of the optical/NIR afterglow is found to decline sharply bluewards to the UV bands, which can be utilized in estimating the redshift. Fitting the SED from the Swift UVOT uvw2bandto the H band, we …

Erratum: "Warm Hcn, C2h2, And Co In The Disk Of Gv Tau'', E L. Gibb, K A. Vanbrunt, Sean D. Brittain, T W. Rettig

Publications

This is an Erratum for the article 2007 ApJ 660 1572

Pulsar Timing As A Probe Of Non-Einsteinlan Polarizations Of Gravitational Waves, K. J. Lee, F. A. Jenet, Richard H. Price

Physics & Astronomy Faculty Publications

Einstein's theory of gravity predicts waves of the distortion of spacetime with two degrees of polarization; alternative theories predict more polarizations, up to a maximum of six. Although laser interferometric gravity wave detectors can be used to search for at least some of the non-Einsteinian polarizations, their configuration is not optimal for the task. By contrast, the angular distribution of pulsars in the sky makes pulsar timing a flexible tool for detecting all polarizations. We give here an analysis of the sensitivity of pulsar timing to an isotropic stochastic gravitational wave background of waves with non-Einsteinian polarizations and conclude that …

Erasing Dark Matter Cusps In Cosmological Galactic Halos With Baryons, Emilio Romano-Diaz, Isaac Shlosman, Yehuda Hoffman, Clayton Heller

Physics & Astronomy: Faculty Publications

We study the central dark matter (DM) cusp evolution in cosmologically grown galactic halos. Numerical models with and without baryons (baryons+DM, hereafter BDM model, and pure DM, PDM model, respectively) are advanced from identical initial conditions, obtained using the Constrained Realization method. The DM cusp properties are contrasted by a direct comparison of pure DM and baryonic models. We find a divergent evolution between the PDM and BDM models within the inner few × 10 kpc region. The PDM model forms an R−1 cusp as expected, while the DM in the BDM model forms a larger isothermal cusp R …

Chemical Analysis Of Five Red Giants In The Globular Cluster M10 (Ngc 6254), Sharina Haynes, Geoffrey Burks, Christian I. Johnson, Catherine A. Pilachowski

Information Systems and Engineering Management Research Publications

We have determined Al, α, Fe-peak, and neutron capture elemental abundances for five red-giant branch (RGB) stars in the Galactic globular cluster M10. Abundances were determined using equivalent width analyses of moderate-resolution (R ∼ 15,000) spectra obtained with the Hydra multifiber positioner and bench spectrograph on the WIYN telescope. The data sample the upper RGB from the luminosity level near the horizontal branch to about 0.5 mag below the RGB tip. We find, in agreement with previous studies, that M10 is moderately metal-poor with [Fe/H] = -1.45 (σ = 0.04). All stars appear enhanced in Al with 〈[Al/Fe]〉 = +0.33 …

The Acs Survey Of Galactic Globular Clusters. Iii. The Double Subgiant Branch Of Ngc 1851, A. P. Milone, L. R. Bedin, G. Piotto, J. Anderson, I. R. King, A. Sarajedini, A. Dotter, B. Chaboyer, A. Marin Franch, S. Majewski, A. Aparicio, M. Hempel, N. E.Q Paust, I. N. Reid, A. Rosenberg, M. Siegel

Dartmouth Scholarship

Photometry with the Hubble Space Telescope Advanced Camera for Surveys (HST ACS) reveals that the subgiant branch (SGB) of the globular cluster NGC 1851 splits into two well-defined branches. If the split is due only to an age effect, the two SGBs would imply two star formation episodes separated by ~1 Gyr. We discuss other anomalies in NGC 1851 that could be interpreted in terms of a double stellar population. Finally, we compare the case of NGC 1851 with the other two globulars known to host multiple stellar populations, and show that all three clusters differ in several important …

Time-Resolved Au-Scale Jets Traced By Masers In The Iras 4a/B Regions Of Ngc 1333, Bruce Wilking, Kevin Marvel, Mark Claussen, Alwyn Wootten

Physics Faculty Works

We present results of VLBI observations of the water masers associated with IRAS 4A and IRAS 4B in the NGC 1333 star-forming region taken in four epochs over a two month period. Both objects have been classified as extremely young sources, and each source is known to be a multiple system. Using the Very Long Baseline Array, we detected 35 masers in epoch I, 40 masers in epoch II, 35 in epoch III, and 24 in epoch IV. Only one identified source in each system is associated with these masers. These data are used to calculate proper motions for the …

The Rapidly Flaring Afterglow Of The Very Bright And Energetic Grb 070125, Adria C. Updike, Josh B. Haislip, Melissa C. Nysewander, Andrew S. Fruchter, D. Alexander Kann, Sylvio Klose, Peter A. Miline, G. Grant Williams, Weikang Zheng, Carl W. Hergenrother

Publications

We report on multiwavelength observations, ranging from X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O i,Si ii,and C iv, implying a likely redshift of z ¼1:547. The well-sampled light curves, in particular from 0.5 to 4 days after the burst, suggest a jet break at 3.7 days, corresponding to a jet opening angle of $7.0, and implying an intrinsic GRB energy in the 1Y10,000 keV band of around E ¼(6:3Y6:9) ; 1051 ergs (based on the fluences measured by the gamma-ray de-tectorsof the IPN).GRB070125 is …

Agn Dusty Tori. I. Handling Of Clumpy Media, Maia Nenkova, Matthew M. Sirocky, Željko Ivezić, Moshe Elitzur

Physics and Astronomy Faculty Publications

According to unified schemes of active galactic nuclei (AGNs), the central engine is surrounded by dusty, optically thick clouds in a toroidal structure. We have recently developed a formalism that for the first time takes proper account of the clumpy nature of the AGN torus. We now provide a detailed report of our findings in a two-paper series. Here we present our general formalism for radiative transfer in clumpy media and construct its building blocks for the AGN problem-the source functions of individual dusty clouds heated by the AGN radiation field. We show that a fundamental difference from smooth density …

The Biomechanics Of Ballistochory In Impatiens Pallida, Lua Del Campo

Pomona Senior Theses

This research is an analysis of the explosive seed dispersal of Impatiens pallida fruit. Data was taken using high-speed video and analyzed using LoggerPro video analysis software. From the videos we discerned a qualitative model for dehiscence, a description of how the process unfolds, and from our data we deduced quantitative values for the velocity, momentum, and energy of the system. We were also able to glean a lower bound of Young’s modulus E of the fruit tissue. These results and the tools of analysis that generate them are the foundation for the development of a theoretical model of the …

Vimos-Vlt Integral Field Kinematics Of The Giant Low Surface Brightness Galaxy Eso 323-G064, Stacy S. Mcgaugh

Faculty Scholarship

Aims. We have studied the bulge and the disk kinematics of the giant low surface brightness galaxy ESO 323-G064 in order to investigate its dynamical properties and the radial mass profile of the dark matter (DM) halo. Methods. We observed the galaxy with integral field spectroscopy (VLT/VIMOS, in IFU configuration), measured the positions of the ionized gas by fitting Gaussian functions to the [O III] λλ4959,5007 and Hβ emission lines, and fit stellar templates to the galaxy spectra to determine velocity and velocity dispersions. We modeled the stellar kinematics in the bulge with spherical Isotropie Jeans models and explored the …

Vignettes From The World Of Gravitational Wave Astrophysics, Shane L. Larson

Colloquia and Seminars

No abstract provided.

Songs From The Milky Way: Our Galaxy In Low Frequency Gravitational Waves, Shane L. Larson

Colloquia and Seminars

No abstract provided.

The Evolution Of Late‐Time Optical Emission From Sn 1986j, Dan Milisavljevic, Robert A. Fesen, Bruno Leibundgut, Robert P. Kirshner

Dartmouth Scholarship

We present late-time optical images and spectra of the Type IIn supernova SN 1986J. HST ACS/WFC images obtained in 2003 February show it to be still relatively bright, with m_F606W = 21.4 and m_F814W = 20.0 mag. Compared to 1994 December HST WFPC2 images, SN 1986J shows a decline of only <1 mag in brightness over 8 years. Ground-based spectra taken in 1989, 1991, and 2007 show a 50% decline in Hα emission between 1989 and 1991, and an order of magnitude drop between 1991 and 2007, along with the disappearance of He I line emissions during the period 1991-2007. The object's [O I] λλ6300, 6364, [O II] λλ7319, 7330 and [O III] λλ4959, 5007 emission lines show two prominent peaks near –1000 and –3500 km s⁻¹, with the more blueshifted component declining significantly in strength between 1991 and 2007. The observed spectral evolution suggests two different origins for SN 1986J's late-time optical emission: dense, shock-heated circumstellar material, which gave rise to the initially bright Hα, He I, and [N II] λ5755 …

SPitzer Irac Infrared Colours Of Submillimetre-Bright Galaxies, Min S. Yun, Itziar Aretxaga, Matthew L.N. Ashby, Jason Austermann, Giovanni G. Fazio, Mauro Giavalisco, Jia Sheng Huang, David H. Hughes, Sungeun Kim, James D. Lowenthal, Thushara Perera, Kim Scott, Grant Wilson, Joshua D. Younger

Astronomy: Faculty Publications

High-redshift submillimetre-bright galaxies identified by blank field surveys at millimetre and submillimetre wavelengths appear in the region of the Infra Red Array Camera (IRAC) colour-colour diagrams previously identified as the domain of luminous active galactic nuclei (AGNs). Our analysis using a set of empirical and theoretical dusty starburst spectral energy distribution (SED) models shows that power-law continuum sources associated with hot dust heated by young (≲100 Myr old), extreme starbursts at z > 2 also occupy the same general area as AGNs in the IRAC colour-colour plots. A detailed comparison of the IRAC colours and SEDs demonstrates that the two populations …

Variation Of The Martian Ionospheric Electron Density From Mars Express Radar Soundings, D. D. Morgan, D. A. Gurnett, D. L. Kirchner, Jane L. Fox, E. Nielsen, J. J. Plaut

Physics Faculty Publications

The Mars Advanced Radar for Subsurface and Ionospheric Sounding aboard Mars Express has been in operation for over 2 years. Between 14 August 2005 and 31 July 2007, we obtain 34,492 ionospheric traces, of which 14,060 yield electron density profiles and 12,291 yield acceptable fits to the Chapman ionospheric model. These results are used to study the Martian ionosphere under changing conditions: the presence or absence of solar energetic particles, solar EUV flux, season, solar zenith angle, and latitude. The 2-year average subsolar maximum electron density n ₀ is 1.62 × 10⁵ cm⁻³, the average subsolar electron …

The Dartmouth Stellar Evolution Database, Aaron Dotter, Brian Chaboyer, Darko Jevremović, Veselin Kostov

Dartmouth Scholarship

The ever-expanding depth and quality of photometric and spectroscopic observations of stellar populations increase the need for theoretical models in regions of age-composition parameter space that are largely unexplored at present. Stellar evolution models that employ the most advanced physics and cover a wide range of compositions are needed to extract the most information from current observations of both resolved and unresolved stellar populations. The Dartmouth Stellar Evolution Database is a collection of stellar evolution tracks and isochrones that spans a range of [Fe/H] from –2.5 to +0.5, [α/Fe] from –0.2 to +0.8 (for [Fe/H] ≤ 0) or +0.2 (for …

A Teaching Intervention To Increase Achievement Of Hispanic Nonscience Majors Taking Physical Science Courses, G. Herold Poelzer, Liang Zeng

Physics & Astronomy Faculty Publications

This quasi-experimental pilot study of nonscience majors taking a physical science course at a university in South Texas was conducted on Hispanic undergraduate students, and is theory based--an application of attribution theory. That the treatment group outperformed the comparison group provides evidence of the positive effect of having students reflect on controllable reasons for their grades and on their subsequent planning of strategies to maintain or improve those grades. (Contains 1 table and 2 figures.)

Some Rather Mechanical Reflections On Symmetry: In Art, Science, Engineering, Mathematics, Etc., Jim Mcgovern

Articles

This Inaugural Lecture consists of some of my rather mechanical, being an engineer, reflections on symmetry in diverse areas such as art, science, engineering, mathematics, etc. I explain what symmetry is to me, giving examples with lots of images and mentioning or at least barely referencing art, science, architecture, engineering, heritage, cosmology, bicycles, flight, invention, ingenuity, history, wallpaper, mathematics, typography, structures, regular shapes, coordinate systems, spacetime, thermodynamics and suchlike.

Globular Clusters In The Outer Galactic Halo: Am-1 And Palomar 14, Aaron Dotter, Ata Sarajedini, Soung-Chul Yang

Dartmouth Scholarship

AM-1, at ~120 kpc, and Palomar 14 (Pal 14), at ~70 kpc, are two of the most distant Galactic globular clusters (GCs) known. We present Hubble Space Telescope Wide Field Planetary Camera 2 photometry of AM-1 and Pal 14 that reveals unprecedented depth and detail in the color-magnitude diagrams of these two clusters. Absolute and relative age measurements confirm that both are younger than the inner halo GC M 3 by 1.5-2 Gyr assuming all three clusters have similar compositions. Thus AM-1 and Pal 14 join Pal 3, Pal 4, and Eridanus as distant GCs with red horizontal branches (HBs) …

Testing Direct Simulation Monte Carlo Methods Against The Fluid Equations In The Inductively Coupled Plasma Mass Spectrometer, William R. Somers

Theses and Dissertations

A Direct Simulation Monte Carlo fluid dynamics code named FENIX has been employed to study gas flow-through properties of the inductively coupled plasma mass spectrometer (ICP-MS). Simulation data have been tested against the Navier-Stokes and heat equations in order to see if FENIX functions properly. The Navier-Stokes and heat equations have been constructed from simulation data and are compared term by term. This comparison shows that FENIX is able to correctly reproduce fluid dynamics throughout the ICP-MS simulation, with an exception immediately behind the ICP-MS sampler cone, where the continuum criterion for the Navier-Stokes equation is not met. Testing the …

High-Resolution Chandra X-Ray Imaging And Spectroscopy Of The Sigma Orionis Cluster, S. L. Skinner, K. R. Sokal, David H. Cohen, M. Gagné, S. P. Owocki, R. H.D. Townsend

Physics & Astronomy Faculty Works

We present results of a 90 ks Chandra X-ray observation of the young sigma Orionis cluster ( age similar to 3 Myr) obtained with the HETGS. We use the high-resolution grating spectrum and moderate-resolution CCD spectrum of the massive central star sigma Ori AB (O9.5 V + B0.5 V) to test wind shock theories of X-ray emission and also analyze the high spatial resolution zero-order ACIS-S image of the central cluster region. Chandra detected 42 X-ray sources on the primary CCD (ACIS-S3). All but five have near-IR or optical counterparts and about one-fourth are variable. Notable high-mass stellar detections are …

Implementation Of Optical Spectra Calculations In Fireball: A Local-Orbital Density Functional Theory Approach, Ivan Grigoryevich Okhrimenko

Theses and Dissertations

We have expanded the capabilities of the ab initio tight-binding molecular dynamics package FIREBALL to include calculations of optical properties. Basic zero order approximation is based on transitions between Kohn-Sham states. Corrections for electron-electron interactions are based on time dependant density functional theory (TDDFT). Consistent with the FIREBALL approach, we use precalculated integrals and approximations to make the program faster.