Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Astrophysics and Astronomy (100)
- Stars, Interstellar Medium and the Galaxy (57)
- Physics (38)
- Cosmology, Relativity, and Gravity (34)
- External Galaxies (26)
-
- Chemistry (5)
- Engineering (5)
- Instrumentation (5)
- Computer Sciences (3)
- Applied Mathematics (2)
- Atomic, Molecular and Optical Physics (2)
- Earth Sciences (2)
- Life Sciences (2)
- Medicine and Health Sciences (2)
- Nuclear (2)
- Optics (2)
- Other Astrophysics and Astronomy (2)
- Acoustics, Dynamics, and Controls (1)
- Analytical, Diagnostic and Therapeutic Techniques and Equipment (1)
- Artificial Intelligence and Robotics (1)
- Biochemistry, Biophysics, and Structural Biology (1)
- Bioimaging and Biomedical Optics (1)
- Biomedical Engineering and Bioengineering (1)
- Biophysics (1)
- Computer-Aided Engineering and Design (1)
- Data Science (1)
- Environmental Health (1)
- Environmental Sciences (1)
- Fluid Dynamics (1)
- Institution
-
- Wayne State University (47)
- Dartmouth College (15)
- University of Kentucky (8)
- Chapman University (5)
- East Tennessee State University (4)
-
- Roger Williams University (4)
- TÜBİTAK (4)
- University at Albany, State University of New York (4)
- University of Nebraska - Lincoln (4)
- Marquette University (3)
- Munster Technological University (3)
- Selected Works (3)
- University of New Hampshire (3)
- Claremont Colleges (2)
- Kennesaw State University (2)
- Trinity University (2)
- University of Nevada, Las Vegas (2)
- West Chester University (2)
- Air Force Institute of Technology (1)
- Brigham Young University (1)
- California Polytechnic State University, San Luis Obispo (1)
- China Coal Technology and Engineering Group (CCTEG) (1)
- Clemson University (1)
- DePaul University (1)
- Edith Cowan University (1)
- Embry-Riddle Aeronautical University (1)
- Georgia College (1)
- Georgia State University (1)
- Louisiana State University (1)
- MBZUAI (1)
- Publication Year
- Publication
-
- Physics and Astronomy Faculty Research Publications (47)
- Dartmouth Scholarship (15)
- Physics and Astronomy Faculty Publications (8)
- Arts & Sciences Faculty Publications (4)
- ETSU Faculty Works (4)
-
- Legacy Theses & Dissertations (2009 - 2024) (4)
- Mathematics, Physics, and Computer Science Faculty Articles and Research (4)
- Turkish Journal of Physics (4)
- Physical Sciences Publications (3)
- Physics & Astronomy (3)
- All HMC Faculty Publications and Research (2)
- Donald Umstadter Publications (2)
- Earth & Space Sciences Faculty Publications (2)
- Faculty and Research Publications (2)
- Physics Faculty Research and Publications (2)
- Physics and Astronomy Faculty Research (2)
- Theses and Dissertations (2)
- All Dissertations (1)
- Australian Security and Intelligence Conference (1)
- Biology, Chemistry, and Environmental Sciences Faculty Articles and Research (1)
- Chemistry Faculty Publications and Presentations (1)
- Chemistry Faculty Research and Publications (1)
- Coal Geology & Exploration (1)
- Computer Vision Faculty Publications (1)
- Department of Physics and Astronomy: Faculty Publications (1)
- Dissertations (1)
- Donald P. Umstadter (1)
- Edward Schmidt Publications (1)
- Electronic Thesis and Dissertation Repository (1)
- Faculty Publications (1)
- Publication Type
- File Type
Articles 121 - 136 of 136
Full-Text Articles in Physical Sciences and Mathematics
The Warps Survey - Iv. The X-Ray Luminosity-Temperature Relation Of High-Redshift Galaxy Clusters, B. W. Fairley, L. R. Jones, C. Scharf, H. Ebeling, E. Perlman, D. Horner, G. Wegner, M. Malkan
The Warps Survey - Iv. The X-Ray Luminosity-Temperature Relation Of High-Redshift Galaxy Clusters, B. W. Fairley, L. R. Jones, C. Scharf, H. Ebeling, E. Perlman, D. Horner, G. Wegner, M. Malkan
Dartmouth Scholarship
We present a measurement of the cluster X-ray luminosity-temperature (L-T) relation out to high redshift (z∼0.8). Combined ROSAT PSPC spectra of 91 galaxy clusters detected in the Wide Angle ROSAT Pointed Survey (WARPS) are simultaneously fitted in redshift and luminosity bins. The resulting temperature and luminosity measurements of these bins, which occupy a region of the high-redshift L-T relation not previously sampled, are compared with existing measurements at low redshift in order to constrain the evolution of the L-T relation. We find the best fit to low-redshift (z<0.2) cluster data, at T …0.2)>
Production Of Energy-Dependent Time Delays In Impulsive Solar Flare Hard X-Ray Emission By Short-Duration Spectral Index Variations, Ted N. La Rosa, Steven N. Shore
Production Of Energy-Dependent Time Delays In Impulsive Solar Flare Hard X-Ray Emission By Short-Duration Spectral Index Variations, Ted N. La Rosa, Steven N. Shore
Faculty and Research Publications
Cross-correlation techniques have been used recently to study the relative timing of solar flare hard X-ray emission at different energies. These studies find that for the majority of the impulsive flares observed with BATSE there is a systematic time delay of a few tens of milliseconds between low (approximate to 50 keV) and higher energy emission (approximate to 100 keV). These time delays have been interpreted as energy-dependent time-of-flight differences for electron propagation from the corona, where they are accelerated, to the chromosphere, where the bulk of the hard X-rays are emitted. We show in this paper that crosscorrelation methods …
Aquila X-1: A Low-Inclination Soft X-Ray Transient, T. Shahbaz, J. R. Thorstensen, P. A. Charles, N. D. Sherman
Aquila X-1: A Low-Inclination Soft X-Ray Transient, T. Shahbaz, J. R. Thorstensen, P. A. Charles, N. D. Sherman
Dartmouth Scholarship
We have obtained I-band photometry of the neutron star X-ray transient Aql X-1 during quiescence. We find a periodicity at 2.487 cycles d−1, which we interpret as twice the orbital frequency (19.30±0.05 h). Folding the data on the orbital period, we model the light-curve variations as the ellipsoidal modulation of the secondary star. We determine the binary inclination to be 20°–30° (90 per cent confidence) and also determine the 95 per cent upper limits to the radial velocity semi-amplitude and rotational broadening of the secondary star to be 117 and 50 km s−1, respectively.
Multiwavelength Blazar Studies, Menas Kafatos
Multiwavelength Blazar Studies, Menas Kafatos
Mathematics, Physics, and Computer Science Faculty Articles and Research
The present report concerns the following projects 'High energy emission from hot accretion disks from active galactic nuclei'; 'OSSE spectral timing and monitoring observations of Cygnus X- 1'; 'OSSE observations of blazars'; and 'Search for correlated time variations of bright EGRET blazars'. The most favored model for the central engine inAGNs is the supermassive black hole hypothesis (Rees 1978). The observed luminosities range from approx. 10 logical and 44-45 erg /s for objects such as Mk 421 and Seyferts to as much as approx. 10logical and 47 for powerful QSOs such as 3C 273 and 3C 279, a large fraction …
Contemporaneous Iue, Euve, And High-Energy Observations Of 3c 273, E. Ramos, Menas Kafatos, A. Fruscione, F. C. Bruhweiler, I. M. Mchardy, R. C. Hartman, L. G. Titarchuk, C. Von Montigny
Contemporaneous Iue, Euve, And High-Energy Observations Of 3c 273, E. Ramos, Menas Kafatos, A. Fruscione, F. C. Bruhweiler, I. M. Mchardy, R. C. Hartman, L. G. Titarchuk, C. Von Montigny
Mathematics, Physics, and Computer Science Faculty Articles and Research
We present the results of our 1994 January and 1995 January observations of the quasar 3C 273 obtained with the International Ultraviolet Explorer (IUE) and the Extreme-Ultraviolet Explorer (EUV E). These observations were part of a large multiwavelength campaign to observe 3C 273 from radio through γ-rays. Our 1995 January photometric observations with the EUV E Lexan/B Deep Survey (DS) instrument indicate strong evidence for variability, at a 99% confidence level, during the 12 day observing period. We have utilized ROSAT PSPC soft X-ray power-law models to correlate with EUV E count rates. Besides variations in the normalization level between …
Gamma-Ray Observations Of Gro J1655-40, R Kroeger, Mark Strickman, J E. Grove, Philip Kaaret, E. Ford, B A. Harmon, Mark L. Mcconnell
Gamma-Ray Observations Of Gro J1655-40, R Kroeger, Mark Strickman, J E. Grove, Philip Kaaret, E. Ford, B A. Harmon, Mark L. Mcconnell
Physics & Astronomy
The bright transient X-ray source GRO J1655-40 = XN Sco 1994 was observed by the OSSE instrument on the Compton Gamma Ray Observatory (GRO). Preliminary results are reported here. The initial outburst from GRO J1655-40 was detected by BATSE on 27 Jul 1994. OSSE observations were made in five separate viewing periods starting between 4 Aug 1994 and 4 Apr 1995. The first, third, and fifth observations are near the peak luminosity. In the second observation, the source flux had dropped by several orders of magnitude and we can only set an upper limit. The fourth observation is a weak …
A Rosat Hri Observation Of The Supernova Remnant G109.1 – 1.0, Alan P. Hurford, Robert A. Fesen
A Rosat Hri Observation Of The Supernova Remnant G109.1 – 1.0, Alan P. Hurford, Robert A. Fesen
Dartmouth Scholarship
We present results of a search using ROSAT HRI data for X-ray spatial substructures in the galactic supernova remnant G109.1 – 1.0 which might indicate a connection between the remnant’s bright X-ray blob and its X-ray pulsar, 1E2259 + 586. A 0.1 – 2.4 keV HRI image, created by combining separate 28- and 22-ks pointings, reveals the presence of a few small-scale X-ray features, including a NE-SW emission ridge in the remnant’s X-ray blob. Two diffuse knots in the X-ray blob, previously suggested as being aligned with the X-ray pulsar, appear to be statistical fluctuations in the Einstein HRI data. …
The Orbital Period Of The Pre-Cataclysmic Binary Re 2013+400 And A Study Of The Atmosphere Of The Dao White Dwarf Primary, M. A. Barstow, M. R. Burleigh, T. A. Fleming, J. B. Holberg, D. Koester, M. C. Marsh, S. R. Rosen, R. G.M. Rutten, S. Sakai, R. W. Tweedy, G. Wegner
The Orbital Period Of The Pre-Cataclysmic Binary Re 2013+400 And A Study Of The Atmosphere Of The Dao White Dwarf Primary, M. A. Barstow, M. R. Burleigh, T. A. Fleming, J. B. Holberg, D. Koester, M. C. Marsh, S. R. Rosen, R. G.M. Rutten, S. Sakai, R. W. Tweedy, G. Wegner
Dartmouth Scholarship
Several pre-cataclysmic binaries, comprising a hot white dwarf with a red dwarf companion, have been discovered as a result of the optical identification of EUV sources from the ROSAT all-sky survey. The optical spectra have the steep blue continuum and Balmer absorption typical of a hot white dwarf, but there are bright, narrow emission lines of H I (and sometimes He I and Ca II) superimposed. An intense campaign of follow-up observations has been devoted to these binary systems. So far, only RE 2013+400 has exhibited any measurable changes in the radial velocities of the emission components, from which it …
Osse Observations In Blazars, K. Mcnaron-Brown, W. N. Johnson, G. V. Jung, R. L. Kinzer, J. D. Kurfess, M. S. Strickman, C. D. Dermer, D. A. Grabelsky, W. R. Purcell, M. P. Ulmer, Menas Kafatos, P. A. Becker, R. Staubert, M. Maisack
Osse Observations In Blazars, K. Mcnaron-Brown, W. N. Johnson, G. V. Jung, R. L. Kinzer, J. D. Kurfess, M. S. Strickman, C. D. Dermer, D. A. Grabelsky, W. R. Purcell, M. P. Ulmer, Menas Kafatos, P. A. Becker, R. Staubert, M. Maisack
Mathematics, Physics, and Computer Science Faculty Articles and Research
Results are reported on observations obtained with the Oriented Scintillation Spectrometer Experiment (OSSE) instrument on the Compton Gamma Ray Observatory (CGRO) of 17 active galactic nuclei (AGNs) known to exhibit blazar properties at other wavelengths. These observations span the period from 1991 June through 1994 May. Of the 33 high-confidence EGRET detections of blazars during CGRO observing phases 1 and 2 (1991 May 16-1993 September 7), OSSE has observed eight and detected five, namely 3C 273, 3C 279, PKS 0528+134, CTA 102, and 3C 454.3. Additionally, OSSE has detected the BL Lac sources H1517+65.6 and PKS 2155-304, which were not …
The 14.8-H Orbital Period Of Gx339-4, P. J. Callanan, P. A. Charles, W. B. Honey, J. R. Thorstensen
The 14.8-H Orbital Period Of Gx339-4, P. J. Callanan, P. A. Charles, W. B. Honey, J. R. Thorstensen
Dartmouth Scholarship
We present the results of photometric observations of the black hole candidate GX339-4, obtained while the system was in an 'off' state. We show that a 14.8-h modulation was present, and provide evidence for a similar periodicity in the 'high' state from a reanalysis of previously published photometry and spectroscopy. The presence of the same period in both states implies that it is likely to be the orbital period of the system. The spectroscopy analysis provides evidence for an apparent change in the systemic velocity of the system. The amplitude of the observed radial velocity variations, however, permits only crude …
Gamma-Ray Emission From Cygnus-X-1 - Emission Mechanisms And Implications For The Standard Model, A Owens, Mark L. Mcconnell
Gamma-Ray Emission From Cygnus-X-1 - Emission Mechanisms And Implications For The Standard Model, A Owens, Mark L. Mcconnell
Physics & Astronomy
No abstract provided.
Gamma-Ray Observations Of Cygnus X-1 And Cygnus X-3 Using A Coded-Aperture Telescope, Mark L. Mcconnell, D J. Forrest, A Owens, P. P. Dunphy, W T. Vestrand, E. L. Chupp
Gamma-Ray Observations Of Cygnus X-1 And Cygnus X-3 Using A Coded-Aperture Telescope, Mark L. Mcconnell, D J. Forrest, A Owens, P. P. Dunphy, W T. Vestrand, E. L. Chupp
Physics & Astronomy
A balloon-borne coded-aperture telescope, measuring gamma-ray photons in the 160 keV to 9.3 MeV range, was used to observe the Cygnus region of the sky on October 1 and 2, 1984. In the 2-9.3-MeV band, evidence is found for a hard spectral component with a mean flux level at the top of the atmosphere of 7.4 + or - 2.5 x 10 to the -7th photons/sq cm per s per keV, inconsistent with the predictions of the inverse Compton models normally used to describe the X-ray emission. Both Cyg X-1 and Cyg X-3 could be observed simultaneously with the telescope. …
Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Thermal Stress Analysis, A. Ballantyne, H.A. Hyman, Clive L. Dym, R.C. Southworth
Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Thermal Stress Analysis, A. Ballantyne, H.A. Hyman, Clive L. Dym, R.C. Southworth
All HMC Faculty Publications and Research
This paper examines the effects of thermal loading and time history upon the thermal stresses developed in lithographic mask structures as would be expected under irradiation by intense soft x rays. The objective of this work was to examine the phenomenology of the interaction and to evaluate the limits placed upon mask dosage. The mechanics of mask failure are examined in terms of single pulse and cumulative, or fatigue, effects. A number of prototypical mask structures are investigated, which show that the application of intense pulsed sources to x‐ray lithography does not reduce the potential utility of the techique. However, …
Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Dynamic Response, Clive L. Dym, A. Ballantyne
Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Dynamic Response, Clive L. Dym, A. Ballantyne
All HMC Faculty Publications and Research
This paper addresses the issue of the dynamic response of thin lithographic mask structures to thermally induced stress fields. In particular, the impact of repetitively pulsed x‐ray sources are examined: the short duration (1–100 nsec) pulses induce large step changes in mask temperatures, which can, in turn, induce a dynamic response. The impact of conductive cooling of the mask is to reduce the repetitively pulsed problem to a series of isolated nearly identical thermal impulses of duration approximately equal to the cooling time. The importance of self‐weight and prestress is examined, and an analysis of the nonlinear dynamic response to …
Simultaneous X-Ray And Optical Observations Of An Ursae Majoris During A Low State, Paula Szkody, Edward G. Schmidt, Lidia Crosa, Robert Schommer
Simultaneous X-Ray And Optical Observations Of An Ursae Majoris During A Low State, Paula Szkody, Edward G. Schmidt, Lidia Crosa, Robert Schommer
Edward Schmidt Publications
X-ray observations throughout the orbital cycle of AN UMa during its low state were conducted with the Einstein Observatory simultaneously with ground-based optical UBV photometry and spectroscopy. The observed low X-ray flux of 7 × 10–13 ergs cm–2 s–1 is a factor of 40 below the high-state X-ray flux, and Fx/Fopt is about a factor of 50 lower than for AM Her and 2A 0311–227. There is marginal evidence for an X-ray eclipse coincident with an optical minimum and for increased X-ray flux at magnetic phase 0.4 which does not correlate with any optical …
Statistical Time-Dependent Model For The Interstellar Gas, H. Gerola, Menas Kafatos, R. Mccray
Statistical Time-Dependent Model For The Interstellar Gas, H. Gerola, Menas Kafatos, R. Mccray
Mathematics, Physics, and Computer Science Faculty Articles and Research
We present models for temperature and ionization structure of low, uniform-density (n ~ 0.3 cm^-3) interstellar gas in a galactic disk which is exposed to soft X-rays from supernova outbursts occurring randomly in space and time. The structure was calculated by computing the time record of temperature and ionization at a given point by Monte Carlo simulation. The calculation yields probability distribution functions for ionized fraction x, temperature T, and their various observable moments. These time-dependent models predict a bimodal temperature distribution of the gas with structure in x, T that agrees with various observations. Cold regions in the low-density …