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Articles 6121 - 6150 of 8865

Full-Text Articles in Astrophysics and Astronomy

The Dynamic X-Ray Sky Of The Local Universe, S. Boggs, C. Wunderer, P. Von Ballmoos, T. Takahashi, N. Gehrels, J. Tueller, M. Baring, J. Beacom, R. Diehl, Dieter H. Hartmann Jan 2010

The Dynamic X-Ray Sky Of The Local Universe, S. Boggs, C. Wunderer, P. Von Ballmoos, T. Takahashi, N. Gehrels, J. Tueller, M. Baring, J. Beacom, R. Diehl, Dieter H. Hartmann

Publications

Over the next decade, we can expect time domain astronomy to flourish at optical and radio wavelengths. In parallel with these efforts, a dedicated transient "machine" operating at higher energies (X-ray band through soft gamma-rays) is required to reveal the unique subset of events with variable emission predominantly visible above 100 eV. Here we focus on the transient phase space never yet sampled due to the lack of a sensitive, wide-field and triggering facility dedicated exclusively to catching high energy transients and enabling rapid coordinated multi-wavelength follow-up. We first describe the advancements in our understanding of known X-ray transients that …

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On The Origin Of The Highest Redshift Gamma-Ray Bursts, Krzysztof Belczynski, Daniel E. Holz, Chris L. Fryer, Edo Berger, Dieter H. Hartmann, Brain O'Shea Jan 2010

On The Origin Of The Highest Redshift Gamma-Ray Bursts, Krzysztof Belczynski, Daniel E. Holz, Chris L. Fryer, Edo Berger, Dieter H. Hartmann, Brain O'Shea

Publications

GRB 080913 and GRB 090423 are the most distant gamma-ray bursts (GRBs) known to date, with spectroscop-ically determined redshifts of z = 6.7 and z = 8.1, respectively. The detection of bursts at this early epoch of the universe significantly constrains the nature of GRBs and their progenitors. We perform population synthesis studies of the formation and evolution of early stars, and calculate the resulting formation rates of short- and long-duration GRBs at high redshift. The peak of the GRB rate from Population II stars occurs at z ∼ 7for a model with efficient/fast mixing of metals, while it is …

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A Spitzer Search For Planetary-Mass Brown Dwarfs With Circumstellar Disks: Candidate Selection, Paul M. Harvey, Daniel T. Jaffe, Katelyn N. Allers, Michael Liu Jan 2010

A Spitzer Search For Planetary-Mass Brown Dwarfs With Circumstellar Disks: Candidate Selection, Paul M. Harvey, Daniel T. Jaffe, Katelyn N. Allers, Michael Liu

Faculty Journal Articles

No abstract provided.

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The Physical And Dynamical Structure Of Serpens - Two Very Different Sub-(Proto)Clusters, A. Duarte-Cabral, G. A. Fuller, N. Peretto, J. Hatchell, Edwin F. Ladd, J. Buckle, J. Richer, S. F. Graves Jan 2010

The Physical And Dynamical Structure Of Serpens - Two Very Different Sub-(Proto)Clusters, A. Duarte-Cabral, G. A. Fuller, N. Peretto, J. Hatchell, Edwin F. Ladd, J. Buckle, J. Richer, S. F. Graves

Faculty Journal Articles

No abstract provided.

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Aztec Half Square Degree Survey Of The Shades Fields - I. Maps, Catalogues And Source Counts, J. E. Austermann, J. S. Dunlop, T. A. Perera, K. S. Scott, G. W. Wilson, I. Aretxaga, D. H. Hughes, O. Almaini, E. L. Chapin, S. C. Chapman, M. Cirasuolo, D. L. Clements, K. E.K. Coppin, L. Dunne, S. Dye, S. A. Eales, E. Egami, D. Farrah, D. Ferrusca, S. Flynn, D. Haig, M. Halpern, E. Ibar, R. J. Ivison, E. Van Kampen, Y. Kang, S. Kim, C. Lacey, James D. Lowenthal, P. D. Mauskopf, R. J. Mclure, A. M.J. Mortier Jan 2010

Aztec Half Square Degree Survey Of The Shades Fields - I. Maps, Catalogues And Source Counts, J. E. Austermann, J. S. Dunlop, T. A. Perera, K. S. Scott, G. W. Wilson, I. Aretxaga, D. H. Hughes, O. Almaini, E. L. Chapin, S. C. Chapman, M. Cirasuolo, D. L. Clements, K. E.K. Coppin, L. Dunne, S. Dye, S. A. Eales, E. Egami, D. Farrah, D. Ferrusca, S. Flynn, D. Haig, M. Halpern, E. Ibar, R. J. Ivison, E. Van Kampen, Y. Kang, S. Kim, C. Lacey, James D. Lowenthal, P. D. Mauskopf, R. J. Mclure, A. M.J. Mortier

Astronomy: Faculty Publications

We present the first results from the largest deep extragalactic mm-wavelength survey undertaken to date. These results are derived from maps covering over 0.7 deg , made at λ = 1.1 mm, using the AzTEC continuum camera mounted on the James Clerk Maxwell Telescope. The maps were made in the two fields originally targeted at λ = 850 μm with the Submillimetre Common-User Bolometer Array (SCUBA) in the SCUBA Half-Degree Extragalactic Survey (SHADES) project, namely the Lockman Hole East (mapped to a depth of 0.9-1.3 mJy rms) and the Subaru/XMM-Newton Deep Field (mapped to a depth of 1.0-1.7 mJy rms). …

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Evidence For Supernova-Synthesized Dust From The Rising Afterglow Of Grb071025 At Z ∼ 5, Daniel A. Perley, J. S. Bloom, C. R. Klein, S. Covino, T. Minezaki, P. Wo´Zniak, W. T. Vestrand, G. G. Williams, P. Milne, N. R. Butler, Adria Updike, T. Kr¨Uhler, P. Afonso, A. Antonelli, L. Cowie, P. Ferrero, J. Greiner, D. H. Hartmann, Y. Kakazu, A. K¨Upc¨U Yoldas¸, A. N. Morgan, P. A. Price, J. X. Prochaska, Y. Yoshii Jan 2010

Evidence For Supernova-Synthesized Dust From The Rising Afterglow Of Grb071025 At Z ∼ 5, Daniel A. Perley, J. S. Bloom, C. R. Klein, S. Covino, T. Minezaki, P. Wo´Zniak, W. T. Vestrand, G. G. Williams, P. Milne, N. R. Butler, Adria Updike, T. Kr¨Uhler, P. Afonso, A. Antonelli, L. Cowie, P. Ferrero, J. Greiner, D. H. Hartmann, Y. Kakazu, A. K¨Upc¨U Yoldas¸, A. N. Morgan, P. A. Price, J. X. Prochaska, Y. Yoshii

Arts & Sciences Faculty Publications

No abstract provided.

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A Very Metal-Poor Damped Lyman-Α System Revealed Through The Most Energetic Grb 090926a, A. Rau, S. Savaglio, T. Kr¨ Uhler, P. Afonso, J. Greiner, S. Klose, P. Schady, S. Mcbreen, R. Filgas, F. Olivares E., A. Rossi, Adria Updike Jan 2010

A Very Metal-Poor Damped Lyman-Α System Revealed Through The Most Energetic Grb 090926a, A. Rau, S. Savaglio, T. Kr¨ Uhler, P. Afonso, J. Greiner, S. Klose, P. Schady, S. Mcbreen, R. Filgas, F. Olivares E., A. Rossi, Adria Updike

Arts & Sciences Faculty Publications

No abstract provided.

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Chandra Observations Of The Radio Galaxy 3c 445 And The Hot Spot X-Ray Emission Mechanism, Eric S. Perlman, Markos Georganopoulos, Emily M. May, Deosthenes Kazanas Jan 2010

Chandra Observations Of The Radio Galaxy 3c 445 And The Hot Spot X-Ray Emission Mechanism, Eric S. Perlman, Markos Georganopoulos, Emily M. May, Deosthenes Kazanas

Aerospace, Physics, and Space Science Faculty Publications

We present new Chandra observations of the radio galaxy 3C 445, centered on its southern radio hot spot. Our observations detect X-ray emission displaced upstream and to the west of the radio-optical hot spot. Attempting to reproduce both the observed spectral energy distribution and the displacement excludes all one-zone models. Modeling of the radio-optical hot spot spectrum suggests that the electron distribution has a low-energy cutoff or break approximately at the proton rest mass energy. The X-rays could be due to external Compton scattering of the cosmic microwave background coming from the fast (Lorentz factor Γ ≈ 4) part of …

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A Multi-Wavelength Spectral And Polarimetric Study Of The Jet Of 3c 264, Eric S. Perlman Jan 2010

A Multi-Wavelength Spectral And Polarimetric Study Of The Jet Of 3c 264, Eric S. Perlman

Aerospace, Physics, and Space Science Faculty Publications

We present a comprehensive multi-band spectral and polarimetric study of the jet of 3C 264 (NGC 3862). Included in this study are three Hubble Space Telescope (HST) optical and ultraviolet polarimetry data sets, along with new and archival Very Large Array radio imaging and polarimetry, a re-analysis of numerous HST broadband data sets from the near infrared to the far ultraviolet, and a Chandra ACIS-S observation. We investigate similarities and differences between optical and radio polarimetry, in both degree of polarization and projected magnetic field direction. We also examine the broadband spectral energy distribution of both the nucleus and jet …

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Magnetic Cloud Boundary Layer Of 9 November 2004 And Its Associated Space Weather Effects, Pingbing Zuo, Fengsi Wei, Xueshang Feng, Xiaojun Xu, Wenbin Song Jan 2010

Magnetic Cloud Boundary Layer Of 9 November 2004 And Its Associated Space Weather Effects, Pingbing Zuo, Fengsi Wei, Xueshang Feng, Xiaojun Xu, Wenbin Song

Aerospace, Physics, and Space Science Faculty Publications

On 9 November 2004, the WIND spacecraft detected a magnetic cloud boundary layer (MCBL) during the interval from 19:07 UT to 20:30 UT. Within the MCBL, there is intense southward magnetic field and the dynamic pressure is rather high, which makes it much geoeffective. Twenty-three minutes later, the MCBL arrived on the magnetopause. An intense geomagnetic storm main phase was driven by the sustaining strong southward magnetic field within the MCBL. During the passage of the MCBL, a typical magnetospheric substorm was triggered. The substorm onset was synthetically identified by the aurora breakup, magnetic dipolarization, dispersionless particle injection, Pi2 pulsation, …

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The Heavily Polluted Atmosphere Of The Daz White Dwarf Galex J193156.8+011745, Stephane Vennes, Adéla Kawka, Péter Németh Jan 2010

The Heavily Polluted Atmosphere Of The Daz White Dwarf Galex J193156.8+011745, Stephane Vennes, Adéla Kawka, Péter Németh

Aerospace, Physics, and Space Science Faculty Publications

We report on the discovery of a new heavily polluted white dwarf. The DAZ white dwarf GALEX J193156.8+011745 was identified in a joint Galaxy Evolution Explorer (GALEX)/GSC survey of ultraviolet-excess objects. Optical spectra obtained at ESO New Technology Telescope show strong absorption lines of magnesium and silicon, and a detailed abundance analysis based on Very Large Telescope-Kueyen UVES spectra reveal super-solar abundances of silicon and magnesium and near-solar abundances of oxygen, calcium and iron. The overall abundance pattern bears the signature of on-going accretion on to the white dwarf atmosphere. The infrared spectral energy distribution shows an excess in the …

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Chandra Observations Of The Radio Galaxy 3c 445 And The Hot Spot X-Ray Emission Mechanism, Eric S. Perlman, Markos Georganopoulos, Emily M. May, Demosthenes Kazanas Jan 2010

Chandra Observations Of The Radio Galaxy 3c 445 And The Hot Spot X-Ray Emission Mechanism, Eric S. Perlman, Markos Georganopoulos, Emily M. May, Demosthenes Kazanas

Aerospace, Physics, and Space Science Faculty Publications

We present new Chandra observations of the radio galaxy 3C 445, centered on its southern radio hot spot. Our observations detect X-ray emission displaced upstream and to the west of the radio-optical hot spot. Attempting to reproduce both the observed spectral energy distribution and the displacement excludes all one-zone models. Modeling of the radio-optical hot spot spectrum suggests that the electron distribution has a low-energy cutoff or break approximately at the proton rest mass energy. The X-rays could be due to external Compton scattering of the cosmic microwave background coming from the fast (Lorentz factor Γ ≈ 4) part of …

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Thunderstorm Characteristics Associated With Rhessi Identified Terrestrial Gamma Ray Flashes, Michael E. Splitt, Steven M. Lazarus, Diana H. Barnes, Joseph R. Dwyer, Hamid K. Rassoul, David M. Smith, Bryna J. Hazelton, Brian W. Grefenstette Jan 2010

Thunderstorm Characteristics Associated With Rhessi Identified Terrestrial Gamma Ray Flashes, Michael E. Splitt, Steven M. Lazarus, Diana H. Barnes, Joseph R. Dwyer, Hamid K. Rassoul, David M. Smith, Bryna J. Hazelton, Brian W. Grefenstette

Aerospace, Physics, and Space Science Faculty Publications

The characteristics of thunderstorms that produce terrestrial gamma-ray flashes (TGFs) observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) are determined using climatological and meteorological data. RHESSI observed TGFs follow diurnal, seasonal, and geographic patterns that are very similar to those of thunderstorms confirming, in part, that these events are directly connected to thunderstorm activity. The TGF producing thunderstorms are shown to be closely associated with tall (ranging from 13.6 km to 17.3 km) tropical thunderstorm systems, a finding that is consistent with theoretical expectations from models of relativistic breakdown that relate the source region to the spectral …

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Acceleration Of Suprathermal Particles By Compressional Plasma Wave Trains In The Solar Wind, Ming Zhang Jan 2010

Acceleration Of Suprathermal Particles By Compressional Plasma Wave Trains In The Solar Wind, Ming Zhang

Aerospace, Physics, and Space Science Faculty Publications

This paper presents a calculation of particle acceleration by an idealized compressional plasma wave train. In this model, suprathermal particles, such as pickup ions, are continuously injected into a wave train consisting of a series of compression or rarefaction regions. The momentum distribution of particles will become broader and broader as they go through the wave train, which is very similar to diffusion in momentum space. The acceleration process is very fast: it does not take too many wave cycles even with a small compression amplitude to reach an asymptotic steady state momentum distribution. In the absence of large-scale adiabatic …

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Diffusion Of Relativistic Runaway Electrons And Implications For Lightning Initiation, Joseph R. Dwyer Jan 2010

Diffusion Of Relativistic Runaway Electrons And Implications For Lightning Initiation, Joseph R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

Using detailed Monte Carlo simulations, the diffusion coefficients for relativistic runaway electron avalanches in air are found for the range of electric field strengths applicable to thunderclouds. Diffusion causes runaway electron avalanches to spread perpendicular to and parallel to the avalanche direction, resulting in much smaller peak conductivities than would be inferred otherwise. The idea that runaway electron avalanches seeded by extensive cosmic ray air showers may initiate lightning has gained considerable popularity in recent years. However, using the diffusion coefficients calculated in this paper along with the avalanche multiplication limit from X-ray and positron feedback, it is found that …

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High-Resolution Cavity-Enhanced Spectroscopy Of Molecular Ion Beams, Manori Perera, Andrew Mills, Brian Siller, Michael Porambo, Kyle Crabtree, Carrie Kauffman, Holger Kreckel, Benjamin Mccall Jan 2010

High-Resolution Cavity-Enhanced Spectroscopy Of Molecular Ion Beams, Manori Perera, Andrew Mills, Brian Siller, Michael Porambo, Kyle Crabtree, Carrie Kauffman, Holger Kreckel, Benjamin Mccall

Scholarship

Molecular ions play a pivotal role in the chemistry of the interstellar medium due to their high reactivity even at low temperature. To identify these ions in interstellar space, it is essential to obtain high resolution laboratory spectra of potential interstellar ions for comparison to observational data. At the University of Illinois, we are developing a Sensitive, Cooled, Resolved Ion BEam Spectrometer (SCRIBES) that will allow us to obtain high resolution infrared direct absorption spectra of rotationally cold molecular ions in the absence of neutral molecules. This instrument can overcome many of the problems that arise when using other spectroscopic …

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Origins Of The Extragalactic Background At 1mm From A Combined Analysis Of The Aztec And Mambo Data In Goods-N, Kyle Penner, Alexandra Pope, Edward Chapin, Thomas Greve, Frank Bertoldi, Mark Brodwin, Ranga-Ram Chary, Christopher Conselice, Kristen Coppin, Mauro Giavalisco, David Hughes, Rob Ivison, Thushara Perera, Douglas Scott, Kimberly Scott, Grant Wilson Jan 2010

Origins Of The Extragalactic Background At 1mm From A Combined Analysis Of The Aztec And Mambo Data In Goods-N, Kyle Penner, Alexandra Pope, Edward Chapin, Thomas Greve, Frank Bertoldi, Mark Brodwin, Ranga-Ram Chary, Christopher Conselice, Kristen Coppin, Mauro Giavalisco, David Hughes, Rob Ivison, Thushara Perera, Douglas Scott, Kimberly Scott, Grant Wilson

Scholarship

We present a study of the cosmic infrared background, which is a measure of the dust obscured activity in all galaxies in the Universe. We venture to isolate the galaxies responsible for the background at 1mm; with spectroscopic and photometric redshifts we constrain the redshift distribution of these galaxies. We create a deep 1.16mm map (sigma ~ 0.5mJy) by combining the AzTEC 1.1mm and MAMBO 1.2mm datasets in GOODS-N. This combined map contains 41 secure detections, 13 of which are new. By averaging the 1.16mm flux densities of individually undetected galaxies with 24um flux densities > 25uJy, we resolve 31--45 per …

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Color-Magnitude Relation And Morphology Of Low-Redshift Ulirgs In Sloan Digital Sky Survey, Yuxi Chen, James D. Lowenthal, Min S. Yun Jan 2010

Color-Magnitude Relation And Morphology Of Low-Redshift Ulirgs In Sloan Digital Sky Survey, Yuxi Chen, James D. Lowenthal, Min S. Yun

Astronomy: Faculty Publications

We present color-magnitude and morphological analysis of 54 low-redshift ultraluminous infrared galaxies (ULIRGs; 0.018 < z < 0.265 with z = 0.151), a subset of the Infrared Astronomical Satellite 1Jy sample, in the Sloan Digital Sky Survey (SDSS). The ULIRGs are both bright and blue: they are on average 1mag brighter in than the SDSS galaxies within the same redshift range, and 0.2mag bluer in g - r. They form a group in the color-magnitude diagram distinct from both the red sequence and the blue cloud formed by the SDSS galaxies: 24 out of the 52 unsaturated objects (46%) lie outside the 90% level number density contour of the SDSS galaxies. The majority (47, or 87%) have the colors typical of the blue cloud, and only four (7%) sources are located in the red sequence. While ULIRGs are popularly thought to be precursors to a QSO phase, we find few (three, or 6%) in the "green valley" where the majority of the X-ray- and IR-selected active galactic nuclei (AGNs) are found. Moreover, none of the AGN-host ULIRGs are found in the green valley. For the 14 previously spectroscopic identified AGNs (28%), we perform point-spread function subtractions and find that on average the central point sources contribute less than one-third to the total luminosity, and that their high optical luminosities and overall blue colors are apparently the result of star formation activity of the host galaxies. Visual inspection of the SDSS images reveals a wide range of morphologies including many close pairs, tidal tails, and otherwise disturbed profiles, in strong support of previous studies and the general view of ULIRGs as major mergers of gas-rich disk galaxies. A detailed morphology analysis using Gini and M coefficients shows that slightly less than one-half (42% in g band) of the ULIRGs are located in the merger region defined by morphology studies of local galaxies, while the remaining sources are located in the region of late-type and irregular galaxies. The heterogeneous distribution of ULIRGs in the G-M space is qualitatively consistent with the results found by numerical simulations of disk-disk mergers, and our study also shows that the measured morphological parameters are systematically affected by the signal-to-noise ratio and thus the merging galaxies can appear in various regions of the G-M parameter space. We briefly discuss the origins of the uncertainties and note that the morphology measurements should be implemented with caution for low physical resolution images. In general, our results reinforce the view that ULIRGs contain young stellar populations and are mergers in progress, but we do not observe the concentration of ULIRGs/AGN in the green valley as found by other studies. Our study provides a uniform comparison sample for studying dusty starbursts at higher redshifts such as Spitzer MIPS 24 μm-selected ULIRGs at z = 1-2 or submillimeter galaxies.

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Search For Gravitational-Wave Inspiral Signals Associated With Short Gamma-Ray Bursts During Ligo's Fifth And Virgo's First Science Run, J. Abadie, B. P. Abbott, R. Abbott, T. Accadia, F. Acernese, R. Adhikari, P. Ajith, B. Allen, G. Allen, E. Amador Ceron, R. S. Amin, S. B. Anderson, W. G. Anderson, F. Antonucci, S. Aoudia, M. A. Arain, M. Araya, K. G. Arun, Y. Aso, S. Aston, P. Astone, P. Aufmuth, C. Aulbert, S. Babak, P. Baker, G. Ballardin, S. Ballmer, D. Barker, F. Barone, B. Barr, P. Barriga, Tiffany Z. Summerscales Jan 2010

Search For Gravitational-Wave Inspiral Signals Associated With Short Gamma-Ray Bursts During Ligo's Fifth And Virgo's First Science Run, J. Abadie, B. P. Abbott, R. Abbott, T. Accadia, F. Acernese, R. Adhikari, P. Ajith, B. Allen, G. Allen, E. Amador Ceron, R. S. Amin, S. B. Anderson, W. G. Anderson, F. Antonucci, S. Aoudia, M. A. Arain, M. Araya, K. G. Arun, Y. Aso, S. Aston, P. Astone, P. Aufmuth, C. Aulbert, S. Babak, P. Baker, G. Ballardin, S. Ballmer, D. Barker, F. Barone, B. Barr, P. Barriga, Tiffany Z. Summerscales

Faculty Publications

Progenitor scenarios for short gamma-ray bursts (short GRBs) include coalescenses of two neutron stars or a neutron star and black hole, which would necessarily be accompanied by the emission of strong gravitational waves. We present a search for these known gravitational-wave signatures in temporal and directional coincidence with 22 GRBs that had sufficient gravitational-wave data available in multiple instruments during LIGO's fifth science run, S5, and Virgo's first science run, VSR1. We find no statistically significant gravitational-wave candidates within a [ - 5, + 1)s window around the trigger time of any GRB. Using the Wilcoxon-Mann-Whitney U-test, we find no …

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Searches For Gravitational Waves From Known Pulsars With Science Run 5 Ligo Data, B. P. Abbott, R. Abbott, F. Acernese, R. Adhikari, P. Ajith, B. Allen, G. Allen, M. Alshourbagy, R. S. Amin, S. B. Anderson, W. G. Anderson, F. Antonucci, S. Aoudia, M. A. Arain, M. Araya, H. Armandula, P. Armor, K. G. Arun, Y. Aso, S. Aston, P. Astone, P. Aufmuth, C. Aulbert, S. Babak, P. Baker, G. Ballardin, S. Ballmer, C. Barker, D. Barker, F. Barone, B. Barr, Tiffany Z. Summerscales Jan 2010

Searches For Gravitational Waves From Known Pulsars With Science Run 5 Ligo Data, B. P. Abbott, R. Abbott, F. Acernese, R. Adhikari, P. Ajith, B. Allen, G. Allen, M. Alshourbagy, R. S. Amin, S. B. Anderson, W. G. Anderson, F. Antonucci, S. Aoudia, M. A. Arain, M. Araya, H. Armandula, P. Armor, K. G. Arun, Y. Aso, S. Aston, P. Astone, P. Aufmuth, C. Aulbert, S. Babak, P. Baker, G. Ballardin, S. Ballmer, C. Barker, D. Barker, F. Barone, B. Barr, Tiffany Z. Summerscales

Faculty Publications

We present a search for gravitational waves from 116 known millisecond and young pulsars using data from the fifth science run of the LIGO detectors. For this search, ephemerides overlapping the run period were obtained for all pulsars using radio and X-ray observations. We demonstrate an updated search method that allows for small uncertainties in the pulsar phase parameters to be included in the search. We report no signal detection from any of the targets and therefore interpret our results as upper limits on the gravitational wave signal strength. The most interesting limits are those for young pulsars. We present …

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Buddhist Thought: Murakami Senshō And Critical Buddhism, A. Aguilar-Arevalo, Sally Koutsoliotas Jan 2010

Buddhist Thought: Murakami Senshō And Critical Buddhism, A. Aguilar-Arevalo, Sally Koutsoliotas

Faculty Journal Articles

No abstract provided.

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Hard Photodisintegration Of A Proton Pair, I. Pomerantz, N. Bubis, K. Allada, A. Beck, B. L. Berman, W. Boeglin, A. Camsonne, M. Canan, K. Chirapatpimol, E. Cisbani Jan 2010

Hard Photodisintegration Of A Proton Pair, I. Pomerantz, N. Bubis, K. Allada, A. Beck, B. L. Berman, W. Boeglin, A. Camsonne, M. Canan, K. Chirapatpimol, E. Cisbani

Physics Faculty Publications

We present a study of high energy photodisintegration of proton-pairs through the γ + 3He → p + p + n channel. Photon energies, Eγ , from 0.8 to 4.7 GeV were used in kinematics corresponding to a proton pair with high relative momentum and a neutron nearly at rest. The s−11 scaling of the cross section, as predicted by the constituent counting rule for two nucleon photodisintegration, was observed for the first time. The onset of the scaling is at a higher energy and the cross section is significantly lower than for deuteron (pn pair) photodisintegration. …

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Longitudinal Scaling Property Of The Charge Balance Function In Au + Au Collisions At √Snn= 200 Gev, B. I. Abelev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, B. D. Anderson, D. Arkhipkin, G. S. Averichev, J. Balewski, L. S. Barnby, S. Bültmann, I. Koralt, D. Plyku Jan 2010

Longitudinal Scaling Property Of The Charge Balance Function In Au + Au Collisions At √Snn= 200 Gev, B. I. Abelev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, B. D. Anderson, D. Arkhipkin, G. S. Averichev, J. Balewski, L. S. Barnby, S. Bültmann, I. Koralt, D. Plyku

Physics Faculty Publications

We present measurements of the charge balance function, from the charged particles, for diverse pseudorapidity and transverse momentum ranges in Au + Au collisions at √sNN = 200 GeV using the STAR detector at RHIC. We observe that the balance function is boost-invariant within the pseudorapidity coverage [ − 1.3 , 1.3 ] . The balance function properly scaled by the width of the observed pseudorapidity window does not depend on the position or size of the pseudorapidity window. This scaling property also holds for particles in different transverse momentum ranges. In addition, we find that the width …

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Begin The Adventure : How To Break The Light Barrier By A.D. 2079 (3rd Ed.), Florentin Smarandache, Homer B. Tilton Jan 2010

Begin The Adventure : How To Break The Light Barrier By A.D. 2079 (3rd Ed.), Florentin Smarandache, Homer B. Tilton

Branch Mathematics and Statistics Faculty and Staff Publications

This edition, the third, has undergone a subtle name change, going from "A.D. 2070" in the title to A.D. 2079 as the timeline is fine-tuned. Because of the almost universal failure to recognize the distinction between physical (reality-based, dynamical) and visual (appearance-based, kinematical) variables, a tremendous volume of mythology arose over the past 100 years centered around Einstein's reality view of the distortions of special relativity. To get a sense of it, we point the reader to Paul J. Nahin's heroic book, Time Machines, 2nd ed.,- to these Tech Notes in particular: TN#6. "A High-Speed Rocket Is a One-Way Time …

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Limit On Continuous Neutrino Emission From Neutron Stars, Itzhak Goldman, Shmuel Nussinov Jan 2010

Limit On Continuous Neutrino Emission From Neutron Stars, Itzhak Goldman, Shmuel Nussinov

Mathematics, Physics, and Computer Science Faculty Articles and Research

The timing data of the binary pulsar PSR1913+16, are used to establish an upper limit on the rate of continuous neutrino emission from neutron stars. Neutrino emission from each of the neutron stars of the binary system, increases the star binding energy and thus translates to a decrease in their masses. This in turn implies an increase with time of the binary period. Using the pulsar data we obtain an upper limit on the allowed rate of mass reduction: vertical bar M vertical bar < 1.1 x 10(-12) yr(-1) M, where M is the total mass of the binary. This constrains exotic nuclear equations of state that predict continuous neutrino emissions. The limit applies also to other channels of energy loss, e. g. axion emission. Continued timing measurements of additional binary pulsars, should yield a stronger limit in the future.

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The Magnetic Field Induced By A Lightning Strikes Indirect Effect Double Exponential Current Waveform, S L. Meredith, S K. Earles, I N. Kostanic, Niescja E. Turner Jan 2010

The Magnetic Field Induced By A Lightning Strikes Indirect Effect Double Exponential Current Waveform, S L. Meredith, S K. Earles, I N. Kostanic, Niescja E. Turner

Physics and Astronomy Faculty Research

Problem statement: Develop a new formula which describes the magnetic field induced by a lightning strike's indirect effect double exponential current waveform. Approach: A novel approach for developing a closed-form solution for the magnetic field from the indirect effect double exponential current waveform will be presented. In the literature, models typically employ the pulse waveform to derive the corresponding electromagnetic fields. However, given the Department of Defense (DoD) has incorporated the double exponential current waveform as part of their "Electromagnetic Environmental Effects Requirements For Systems", we felt it important to develop a solution for the magnetic field which …

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A New Method For Describing The Horizontal Electric Field Induced By A Lightning Strike Return Stroke, S L. Meredith, S K. Earles, Niescja E. Turner Jan 2010

A New Method For Describing The Horizontal Electric Field Induced By A Lightning Strike Return Stroke, S L. Meredith, S K. Earles, Niescja E. Turner

Physics and Astronomy Faculty Research

No abstract provided.

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First Results On Terrestrial Gamma Ray Flashes From The Fermi Gamma-Ray Burst Monitor, Michael S. Briggs, Joseph R. Dwyer Jan 2010

First Results On Terrestrial Gamma Ray Flashes From The Fermi Gamma-Ray Burst Monitor, Michael S. Briggs, Joseph R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

The Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope detected 12 intense terrestrial gamma ray flashes (TGFs) during its first year of observation. Typical maximum energies for most of the TGFs are ∼30 MeV, with one TGF having a 38 MeV photon; two of the TGFs are softer and longer than the others. After correcting for instrumental effects, a representative bright TGF is found to have a fluence of ∼0.7 photons cm-2. Pulses are either symmetrical or have faster risetimes than fall times; they are well fit with Gaussian or lognormal functions. The fastest risetime observed was 7 …

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Associations Between Fermi Gamma-Ray Burst Monitor Terrestrial Gamma Ray Flashes And Sferics From The World Wide Lightning Location Network, Valerie Connaughton, Eric S. Cramer, Joseph R. Dwyer Jan 2010

Associations Between Fermi Gamma-Ray Burst Monitor Terrestrial Gamma Ray Flashes And Sferics From The World Wide Lightning Location Network, Valerie Connaughton, Eric S. Cramer, Joseph R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

We report on a search for correlations between terrestrial gamma ray flashes (TGFs) detected by the Fermi Gamma-ray Burst Monitor (GBM) and lightning strokes measured using the World Wide Lightning Location Network (WWLLN). We associate 15 of a total 50 GBM-detected TGFs with individual discharges. We establish the relative timing between the TGF and the lightning stroke to an accuracy of <50 s, and find that in 13 of these 15 lightning-TGF associations, the lightning stroke and the peak of the TGF are simultaneous to ∼40 μs. This suggests that a large fraction of TGFs are coincident with lightning discharges. The two nonsimultaneous associations do not show a consistent TGF-lightning stroke temporal sequence. All 15 associations are with sferics within 300 km of the subspacecraft position. For those TGFs not correlated with a particular lightning stroke, we find storm activity within 300 km of the subspacecraft position in all but four of the TGFs. For three of these four TGFs, we find storm activity very close to one of the magnetic footprints of the spacecraft position. We associate the subspacecraft TGFs with gamma ray events and the footprint events with electrons traveling along magnetic field lines before hitting the Fermi spacecraft.

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The Zeeman Effect In The Sobolev Approximation Ii. Radial Split Monopole Fields And The ‘Heartbeat’ Stokes V Profile., K. Gayley, Richard Ignace Jan 2010

The Zeeman Effect In The Sobolev Approximation Ii. Radial Split Monopole Fields And The ‘Heartbeat’ Stokes V Profile., K. Gayley, Richard Ignace

ETSU Faculty Works

We calculate the circularly polarized Stokes V(λ) profile for emission lines, formed in hot-star winds threaded with a weak radial magnetic field. For simplicity, the field is treated as a split monopole under the assumptions that it has been radially combed by the wind, and rotation is not playing a central role. Invoking the weak-field approximation, we find that the V(λ) profile has a characteristic “heartbeat” shape exhibiting multiple sign inversions, which might be mistaken for noise in the absence of theoretical guidance. We also conclude that there is a tendency for the V(λ) profile to integrate to zero on …

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