Astrophysics and Astronomy Commons^™

Extending Newton’S Apsidal Theorem: Effective Angular Momentum, Cameron J. Tuckerman

Undergraduate Research Posters 2012

Apsidal Shift, or the angular displacement of the orbital apses, is an important quantity in the study of the orbits of planets, starts, and other celestial bodies. The apparent lack of shift of our nearby planets is that on which Sir Isaac Newton based his assumption of the inverse-square relationship in Universal Gravity. We are able to find excellent approximations for the Apsidal Shift and use our results to generalize Newton's Apsidal Theorem.

Pumping Up The [N I] Nebular Lines, Gary J. Ferland, W. J. Henney, C. R. O'Dell, R. L. Porter, P. A. M. Vanhoof, R. J. R. Williams

Physics and Astronomy Faculty Publications

The optical [N I] doublet near 5200 Å is anomalously strong in a variety of emission-line objects. We compute a detailed photoionization model and use it to show that pumping by far-ultraviolet (FUV) stellar radiation previously posited as a general explanation applies to the Orion Nebula (M42) and its companion M43; but, it is unlikely to explain planetary nebulae and supernova remnants. Our models establish that the observed nearly constant equivalent width of [N I] with respect to the dust-scattered stellar continuum depends primarily on three factors: the FUV to visual-band flux ratio of the stellar population, the optical properties …

Variability Of The Blazar 4c 38.41 (B3 1633+382) From Ghz Frequencies To Gev Energies, Niall Smith, Et. Al.

Blackrock Castle Observatory Publications

Context. After years of modest optical activity, the quasar-type blazar 4C 38.41 (B3 1633+382) experienced a large outburst in 2011, which was detected throughout the entire electromagnetic spectrum, renewing interest in this source.

Aims. We present the results of low-energy multifrequency monitoring by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) consortium and collaborators, as well as those of spectropolarimetric/spectrophotometric monitoring at the Steward Observatory. We also analyse high-energy observations of the Swift and Fermi satellites. This combined study aims to provide insights into the source broad-band emission and variability properties.

Methods. We assemble …

Reevaluating The Mass-Radius Relation For Low-Mass, Main-Sequence Stars, Gregory A. Feiden, Brian Chaboyer

Dartmouth Scholarship

We examine the agreement between the observed and theoretical low-mass (<0.8 M _☉) stellar main-sequence mass-radius relationship by comparing detached eclipsing binary (DEB) data with a new, large grid of stellar evolution models. The new grid allows for a realistic variation in the age and metallicity of the DEB population, characteristic of the local galactic neighborhood. Overall, our models do a reasonable job of reproducing the observational data. A large majority of the models match the observed stellar radii to within 4%, with a mean absolute error of 2.3%. These results represent a factor of two improvement compared to …

A Four-Year Xmm-Newton/Chandra Monitoring Campaign Of The Galactic Centre: Analysing The X-Ray Transients, N. Degenaar, R. Wijnands, E. M. Cackett, J. Homan, J. J. M. In 'T Zand, E. Kuulkers, T. J. Maccarone, M. Van Der Klis

Physics and Astronomy Faculty Research Publications

We report on the results of a four-year long X-ray monitoring campaign of the central 1.2 square degrees of our Galaxy, performed with Chandra and XMM-Newton between 2005 and 2008. Our study focuses on the properties of transient X-ray sources that reach 2-10 keV luminosities of L_X ≳ 10³⁴ erg s^-1 for an assumed distance of 8 kpc. There are 17 known X-ray transients within the field of view of our campaign, eight of which were detected in outburst during our observations: the transient neutron star low-mass X-ray binaries GRS 1741-2853, AX J1745.6-2901, SAX J1747.0-2853, KS 1741-293 …

On The Role Of The Accretion Disk In Black Hole Disk-Jet Connections, J. M. Miller, G. G. Pooley, A. C. Fabian, M. A. Nowak, R. C. Reis, E. M. Cackett, K. Pottschmidt, J. Wilms

Physics and Astronomy Faculty Research Publications

Models of jet production in black hole systems suggest that the properties of the accretion disk—such as its mass accretion rate, inner radius, and emergent magnetic field—should drive and modulate the production of relativistic jets. Stellar-mass black holes in the "low/hard" state are an excellent laboratory in which to study disk-jet connections, but few coordinated observations are made using spectrometers that can incisively probe the inner disk. We report on a series of 20 Suzaku observations of Cygnus X-1 made in the jet-producing low/hard state. Contemporaneous radio monitoring was done using the Arcminute MicroKelvin Array radio telescope. Two important and …

A Deep Search For Host Galaxies Of Grbs With No Detected Optical Afterglow, A. Rossi, S. Klose, P. Ferrero, J. Greiner, L. A. Arnold, E. Gonslaves, Dieter H. Hartmann, A. C. Updike, D. A. Kann, T. Krühler

Publications

Context. Gamma-ray bursts (GRBs) can provide information about star formation at high redshifts. Even in the absence of a bright optical/near-infrared/radio afterglow, the high detection rate of X-ray afterglows by Swift/XRT and its localization precision of 2–3 arcsec facilitates the identification and the study of GRB host galaxies. Aims. We focus on the search for the host galaxies of 17 bursts with arcsec-sized XRT error circles but no detected long-wavelength afterglow, in spite of their deep and rapid follow-up observations. Three of these events can also be classified as truly dark bursts, i.e., the observed upper limit on the optical …

Improved He I Emissivities In The Case B Approximation, R. L. Porter, Gary J. Ferland, P. J. Storey, M. J. Detisch

Physics and Astronomy Faculty Publications

We update our prior work on the case B collisional-recombination spectrum of He i to incorporate ab initio photoionization cross-sections. This large set of accurate, self-consistent cross-sections represents a significant improvement in He i emissivity calculations because it largely obviates the piecemeal nature that has marked all modern works. A second, more recent set of ab initio cross-sections is also available, but we show that those are less consistent with bound-bound transition probabilities than our adopted set. We compare our new effective recombination coefficients with our prior work and our new emissivities with those by other researchers, and we conclude …

The Chandra X-Ray Point-Source Catalog In The Deep2 Galaxy Redshift Survey Fields, A. D. Goulding, W. R. Forman, R. C. Hickox, C. Jones

Dartmouth Scholarship

We present the X-ray point-source catalog produced from the Chandra Advanced CCD Imaging Spectrometer (ACIS-I) observations of the combined \sim3.2 deg2 DEEP2 (XDEEP2) survey fields, which consist of four ~0.7-1.1 deg2 fields. The combined total exposures across all four XDEEP2 fields range from ~10ks-1.1Ms. We detect X-ray point-sources in both the individual ACIS-I observations and the overlapping regions in the merged (stacked) images. We find a total of 2976 unique X-ray sources within the survey area with an expected false-source contamination of ~30 sources (~1%). We present the combined logN-logS distribution of sources detected across the XDEEP2 survey fields and …

Hot Methane Line Lists For Exoplanet And Brown Dwarf Atmospheres, Robert J. Hargreaves, Christopher A. Beale, Laurent Michaux, Melis Irfan, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

We present comprehensive experimental line lists of methane (CH₄) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for the temperatures 300-1400°C at twelve 100°C intervals spanning the 960-5000 cm^-1 (2.0-10.4 μm) region of the infrared. This range encompasses the dyad, pentad, and octad regions, i.e., all fundamental vibrational modes along with a number of combination, overtone and hot bands. Using our CH₄ spectra, we have estimated empirical lower state energies (E_low in cm^-1) and our values have been incorporated into the line lists along …

The 1.17 Day Orbit Of The Double-Degenerate (Da+Dq) Nltt 16249, S. Vennes, A. Kawka, S. J. O'Toole, J. R. Thorstensen

Dartmouth Scholarship

New spectroscopic observations show that the double degenerate system NLTT 16249 is in a close orbit (a = 5.6+/-0.3 R_sun) with a period of 1.17 d. The total mass of the system is estimated between 1.47 and 2.04 M_sun but it is not expected to merge within a Hubble time-scale (t_merge ~ 10^11 yr). Vennes & Kawka (2012, ApJ, 745, L12) originally identified the system because of the peculiar composite hydrogen (DA class) and molecular (C_2--DQ class--and CN) spectra and the new observations establish this system as the first DA plus DQ close double degenerate. Also, the DQ component was …

Nanoscale Surface Patterning And Applications: Using Top-Down Patterning Methods To Aid Bottom-Up Fabrication, Anthony Craig Pearson

Theses and Dissertations

Bottom-up self-assembly can be used to create structures with sub-20 nm feature sizes or materials with advanced electrical properties. Here I demonstrate processes to enable such self-assembling systems including block copolymers and DNA origami, to be integrated into nanoelectronic devices. Additionally, I present a method which utilizes the high stability and electrical conductivity of graphene, which is a material formed using a bottom-up growth process, to create archival data storage devices. Specifically, I show a technique using block copolymer micelle lithography to fabricate arrays of 5 nm gold nanoparticles, which are chemically modified with a single-stranded DNA molecule and used …

Florida Energy Assurance Plan, Niescja E. Turner, W Murtagh, K Guthrie, K Nykyri, W A. Radasky, E Senkowicz

Physics and Astronomy Faculty Research

This spring, Florida held the nations first statewide emergency preparedness training and exercises geared specifically to the aftermath of severe geomagnetic events. Funded by the State of Florida Division of Emergency Management (FDEM) via a Department of Energy grant and held in collaboration with Watch House International, Inquesta Corporation, and the Florida Institute of Technology, the 17-19 April 2012 workshop had 99 on-site attendees in an oceanfront hotel in Melbourne, Florida, as well as 16 over live Web streaming. The workshop was the capstone to a three-month season of 21 regional space weather training sessions and workshops serving 386 attendees …

The Lick–Carnegie Survey: A New Two-Planet System Around The Star Hd 207832, Nader Haghighipour, R. Paul Butler, Eugenio J. Rivera, Gregory W. Henry, Steve Vogt

Information Systems and Engineering Management Research Publications

Keck/HIRES precision radial velocities of HD 207832 indicate the presence of two Jovian-type planetary companions in Keplerian orbits around this G star. The planets have minimum masses of Msin i = 0.56 MJup and 0.73 MJup, with orbital periods of ∼162 and ∼1156 days, and eccentricities of 0.13 and 0.27, respectively. Strömgren b and y photometry reveals a clear stellar rotation signature of the host star with a period of 17.8 days, well separated from the period of the radial velocity variations, reinforcing their Keplerian origin. The values of the semimajor axes of the planets suggest that these objects have …

Multiwavelength Observations Of The Agn 1es 0414+009 With Veritas, Fermi-Lat, Swift-Xrt, And Mdm, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We present observations of the BL Lac object 1ES 0414+009 in the >200 GeV gamma-ray band by the VERITAS array of Cherenkov telescopes. 1ES 0414+009 was observed by VERITAS between 2008 January and 2011 February, resulting in 56.2 hr of good quality pointed observations. These observations resulted in a detection of 822 events from the source corresponding to a statistical significance of 6.4 standard deviations (6.4σ) above the background. The source flux, showing no evidence for variability, is measured as (5.2 ± 1.1stat ± 2.6sys) × 10–12 photons cm–2 s–1 above 200 GeV, equivalent to approximately 2% of the Crab …

High-Velocity Outflows Without Agn Feedback: Eddington-Limited Star Formation In Compact Massive Galaxies, Aleksandar M. Diamond-Stanic, John Moustakas, Christy A. Tremonti, Alison L. Coil, Ryan C. Hickox

Dartmouth Scholarship

We present the discovery of compact, obscured star formation in galaxies at z ~ 0.6 that exhibit 1000 km s^–1 outflows. Using optical morphologies from the Hubble Space Telescope and infrared photometry from the Wide-field Infrared Survey Explorer, we estimate star formation rate (SFR) surface densities that approach Σ_SFR ≈ 3000 M _☉ yr^–1 kpc^–2, comparable to the Eddington limit from radiation pressure on dust grains. We argue that feedback associated with a compact starburst in the form of radiation pressure from massive stars and ram pressure from supernovae and stellar winds is sufficient …

A Multi-Wavelength Study Of The Jet, Lobes, And Core Of The Quasar Pks 2101-490, Leith E.H. Godfrey, Eric S. Perlman

Aerospace, Physics, and Space Science Faculty Publications

We present a detailed study of the x-ray, optical, and radio emission from the jet, lobes, and core of the quasar PKS 2101−490 as revealed by new Chandra, Hubble Space Telescope (HST), and ATCA images. We extract the radio to x-ray spectral energy distributions from seven regions of the 13'' jet, and model the jet x-ray emission in terms of Doppler beamed inverse Compton scattering of the cosmic microwave background (IC/CMB) for a jet in a state of equipartition between particle and magnetic field energy densities. This model implies that the jet remains highly relativistic hundreds of kiloparsecs from the …

High-Mass, Four-Planet Configurations For Hr 8799: Constraining The Orbital Inclination And Age Of The System, Jeffrey J. Sudol, Nader Haghighipour

Physics & Engineering Faculty Publications

No abstract provided.

Implications For The Origin Of Grb 051103 From Ligo Observations, J. Abadie, B. P. Abbott, T. D. Abbott, R. Abbott, M. Abernathy, C. Adams, R. Adhikari, C. Affeldt, P. Ajith, B. Allen, G. S. Allen, E. Amador Ceron, D. Amariutei, R. S. Amin, S. B. Anderson, W. G. Anderson, K. Arai, M. A. Arain, M. C. Araya, S. M. Aston, D. Atkinson, P. Aufmuth, C. Aulbert, B. E. Aylott, S. Babak, P. Baker, S. Ballmer, D. Barker, S. Barnum, B. Barr, P. Barriga, Tiffany Z. Summerscales

Faculty Publications

We present the results of a LIGO search for gravitational waves (GWs) associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst (GRB) whose electromagnetically determined sky position is coincident with the spiral galaxy M81, which is 3.6Mpc from Earth. Possible progenitors for short-hard GRBs include compact object mergers and soft gamma repeater (SGR) giant flares. A merger progenitor would produce a characteristic GW signal that should be detectable at a distance of M81, while GW emission from an SGR is not expected to be detectable at that distance. We found no evidence of a GW signal associated with GRB 051103. …

Implications For The Origin Of Grb 051103 From Ligo Observations, J. Abadie, B. P. Abbott, T. D. Abbott, Matthew Benacquista, Teviet Creighton, Soumya Mohanty, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano

Physics & Astronomy Faculty Publications

We present the results of a LIGO search for gravitational waves (GWs) associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst (GRB) whose electromagnetically determined sky position is coincident with the spiral galaxy M81, which is 3.6Mpc from Earth. Possible progenitors for short-hard GRBs include compact object mergers and soft gamma repeater (SGR) giant flares. A merger progenitor would produce a characteristic GW signal that should be detectable at a distance of M81, while GW emission from an SGR is not expected to be detectable at that distance. We found no evidence of a GW signal associated with GRB 051103. …