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Full-Text Articles in Physics
X-Ray Swift Observations Of Sn 2018cow, L E. Rivera Sandoval, T J. Maccarone, A Corsi, P J. Brown, David Pooley, J C. Wheeler
X-Ray Swift Observations Of Sn 2018cow, L E. Rivera Sandoval, T J. Maccarone, A Corsi, P J. Brown, David Pooley, J C. Wheeler
Physics and Astronomy Faculty Research
Supernova (SN) 2018cow is an optical transient detected in the galaxy CGCG 137–068. It has been classified as a SN due to various characteristics in its optical spectra. The transient is also a bright X-ray source. We present results of the analysis of ∼ 62 ks of X-ray observations taken with the Neil Gehrels Swift Observatory over 27 days. We found a variable behavior in the 0 . 3 − 10 keV X-ray light curve of SN 2018cow, with variability timescales of days. The observed X-ray variability could be due to the interaction between the SN ejecta and a non-uniform …
Spatially Offset Active Galactic Nuclei. Ii. Triggering In Galaxy Mergers, R Scott Barrows, Julia M. Comerford, Jenny E. Greene, David Pooley
Spatially Offset Active Galactic Nuclei. Ii. Triggering In Galaxy Mergers, R Scott Barrows, Julia M. Comerford, Jenny E. Greene, David Pooley
Physics and Astronomy Faculty Research
Galaxy mergers are likely to play a role in triggering active galactic nuclei (AGNs), but the conditions under which this process occurs are poorly understood. In Paper I, we constructed a sample of spatially offset X-ray AGNs that represent galaxy mergers hosting a single AGN. In this paper, we use our offset AGN sample to constrain the parameters that affect AGN observability in galaxy mergers. We also construct dual-AGN samples with similar selection properties for comparison. We find that the offset AGN fraction shows no evidence for a dependence on AGN luminosity, while the dual-AGN fractions show stronger evidence for …
Hst Imaging Of The Dusty Filaments And Nucleus Swirl In Ngc4696 At The Centre Of The Centaurus Cluster, A. C. Fabian, S. A. Walker, H. R. Russell, C. Pinto, R. E. A. Canning, P. Salome, J. S. Sanders, G. B. Taylor, E. G. Zweibel, C. J. Conselice, F. Combes, C. S. Crawford, Gary J. Ferland, J. S. Gallagher Iii, N. A. Hatch, R. M. Johnstone, C. S. Reynolds
Hst Imaging Of The Dusty Filaments And Nucleus Swirl In Ngc4696 At The Centre Of The Centaurus Cluster, A. C. Fabian, S. A. Walker, H. R. Russell, C. Pinto, R. E. A. Canning, P. Salome, J. S. Sanders, G. B. Taylor, E. G. Zweibel, C. J. Conselice, F. Combes, C. S. Crawford, Gary J. Ferland, J. S. Gallagher Iii, N. A. Hatch, R. M. Johnstone, C. S. Reynolds
Physics and Astronomy Faculty Publications
Narrow-band HST imaging has resolved the detailed internal structure of the 10 kpc diameter H α+[N II] emission line nebulosity in NGC4696, the central galaxy in the nearby Centaurus cluster, showing that the dusty, molecular, filaments have a width of about 60 pc. Optical morphology and velocity measurements indicate that the filaments are dragged out by the bubbling action of the radio source as part of the active galactic nucleus feedback cycle. Using the drag force we find that the magnetic field in the filaments is in approximate pressure equipartition with the hot gas. The filamentary nature of the …
Reconciling Ag-Star Formation, The Soltan Argument, And Meier's Paradox, David Garofalo, Matthew I. Kim, Damian J. Christian, Emily Hollingworth
Reconciling Ag-Star Formation, The Soltan Argument, And Meier's Paradox, David Garofalo, Matthew I. Kim, Damian J. Christian, Emily Hollingworth
Faculty and Research Publications
We provide a theoretical context for understanding the recent work of Kalfountzou et al. showing that star formation is enhanced at lower optical luminosity in radio-loud quasars. Our proposal for coupling the assumption of collimated FRII quasar-jet-induced star formation with lower accretion optical luminosity also explains the observed jet power peak in active galaxies at higher redshift compared to the peak in accretion power, doing so in a way that predicts the existence of a family of radio-quiet active galactic nuclei associated with rapidly spinning supermassive black holes at low redshift, as mounting observations suggest. The relevance of this work …
Strong Variability Of The Coronal Line Region In Ngc 5548, Hermine Landt, Martin J. Ward, Katrien C. Steenbrugge, Gary J. Ferland
Strong Variability Of The Coronal Line Region In Ngc 5548, Hermine Landt, Martin J. Ward, Katrien C. Steenbrugge, Gary J. Ferland
Physics and Astronomy Faculty Publications
We present the second extensive study of the coronal line variability in an active galaxy. Our data set for the well-studied Seyfert galaxy NGC 5548 consists of five epochs of quasi-simultaneous optical and near-infrared spectroscopy spanning a period of about five years and three epochs of X-ray spectroscopy overlapping in time with it. Whereas the broad emission lines and hot dust emission varied only moderately, the coronal lines varied strongly. However, the observed high variability is mainly due to a flux decrease. Using the optical [Fe vii] and X-ray O vii emission lines we estimate that the coronal line gas …
The Young Radio Lobe Of 3c 84: Inferred Gas Properties In The Central 10 Pc, Yutaka Fujita, Nozomu Kawakatu, Isaac Shlosman, Hirotaka Ito
The Young Radio Lobe Of 3c 84: Inferred Gas Properties In The Central 10 Pc, Yutaka Fujita, Nozomu Kawakatu, Isaac Shlosman, Hirotaka Ito
Physics and Astronomy Faculty Publications
We analyse the environment of the supermassive black hole (SMBH) in the centre of a massive elliptical galaxy NGC 1275 in the Perseus cluster, hosting the radio source 3C 84. We focus on the young radio lobe observed inside the estimated Bondi accretion radius, and discusss the momentum balance between the jet associated with the lobe and the surrounding gas. The results are compared with the proper motion of the radio lobe obtained with the very long baseline interferometry. We find that under assumption of a high-density environment ( ≳ 100 cm−3), the jet power must be comparable …
Deep Chandra, Hst-Cos, And Megacam Observations Of The Phoenix Cluster: Extreme Star Formation And Agn Feedback On Hundred Kiloparsec Scales, Michael Mcdonald, B. R. Mcnamara, Reinout J. Van Weeren, Douglas E. Applegate, Matthew Bayliss, Marshall W. Bautz, Bradford A. Benson, John E. Carlstrom, Lindsey E. Bleem, Marios Chatzikos, A. C. Edge, A. C. Fabian, Gordon P. Garmire, Julie Hlavacek-Larrondo, Christine Jones-Forman, Adam B. Mantz, Eric D. Miller, Brian Stalder, Sylvain Veilleux, John A. Zuhone
Deep Chandra, Hst-Cos, And Megacam Observations Of The Phoenix Cluster: Extreme Star Formation And Agn Feedback On Hundred Kiloparsec Scales, Michael Mcdonald, B. R. Mcnamara, Reinout J. Van Weeren, Douglas E. Applegate, Matthew Bayliss, Marshall W. Bautz, Bradford A. Benson, John E. Carlstrom, Lindsey E. Bleem, Marios Chatzikos, A. C. Edge, A. C. Fabian, Gordon P. Garmire, Julie Hlavacek-Larrondo, Christine Jones-Forman, Adam B. Mantz, Eric D. Miller, Brian Stalder, Sylvain Veilleux, John A. Zuhone
Physics and Astronomy Faculty Publications
We present new ultraviolet, optical, and X-ray data on the Phoenix galaxy cluster (SPT-CLJ2344-4243). Deep optical imaging reveals previously undetected filaments of star formation, extending to radii of ~50–100 kpc in multiple directions. Combined UV-optical spectroscopy of the central galaxy reveals a massive (2 x 109 M⊙), young (~4.5 Myr) population of stars, consistent with a time-averaged star formation rate of 610 ± 50 M⊙ yr−1. We report a strong detection of O ᴠɪ λλ1032,1038, which appears to originate primarily in shock-heated gas, but may contain a substantial contribution (>1000 M⊙ …
Variability Of The Coronal Line Region In Ngc 4151, Hermine Landt, Martin J. Ward, Katrien C. Steenbrugge, Gary J. Ferland
Variability Of The Coronal Line Region In Ngc 4151, Hermine Landt, Martin J. Ward, Katrien C. Steenbrugge, Gary J. Ferland
Physics and Astronomy Faculty Publications
We present the first extensive study of the coronal line variability in an active galaxy. Our data set for the nearby source NGC 4151 consists of six epochs of quasi-simultaneous optical and near-infrared spectroscopy spanning a period of about 8 yr and five epochs of X-ray spectroscopy overlapping in time with it. None of the coronal lines showed the variability behaviour observed for the broad emission lines and hot dust emission. In general, the coronal lines varied only weakly, if at all. Using the optical [Fe vii] and X-ray O vii emission lines we estimate that the coronal line gas …
Compact Source Of Narrowband And Tunable X-Rays For Radiography, Sudeep Banerjee, Shouyuan Chen, Nathan D. Powers, Daniel Haden, Cheng Liu, Grigory V. Golovin, Jun Zhang, Baozhen Zhao, S. Clarke, Sara Pozzi, Jack Silano, H. Karwowski, Donald Umstadter
Compact Source Of Narrowband And Tunable X-Rays For Radiography, Sudeep Banerjee, Shouyuan Chen, Nathan D. Powers, Daniel Haden, Cheng Liu, Grigory V. Golovin, Jun Zhang, Baozhen Zhao, S. Clarke, Sara Pozzi, Jack Silano, H. Karwowski, Donald Umstadter
Donald Umstadter Publications
We discuss the development of a compact X-ray source based on inverse-Compton scattering with a laser-driven electron beam. This source produces a beam of high-energy X-rays in a narrow cone angle (5–10 mrad), at a rate of 108 photons-s_1. Tunable operation of the source over a large energy range, with energy spread of ~50%, has also been demonstrated. Photon energies >10 MeV have been obtained. The narrowband nature of the source is advantageous for radiography with low dose, low noise, and minimal shielding.
The Host Galaxies Of X-Ray Selected Active Galactic Nuclei To Z = 2.5: Structure, Star Formation, And Their Relationships From Candels And Herschel/Pacs, Dale D. Kocevski, D. J. Rosario, D. H. Mcintosh, A. Van Der Wel, J. Kartaltepe, P. Lang, P. Santini, S. Wuyts, D. Lutz, M. Rafelski, C. Villforth
The Host Galaxies Of X-Ray Selected Active Galactic Nuclei To Z = 2.5: Structure, Star Formation, And Their Relationships From Candels And Herschel/Pacs, Dale D. Kocevski, D. J. Rosario, D. H. Mcintosh, A. Van Der Wel, J. Kartaltepe, P. Lang, P. Santini, S. Wuyts, D. Lutz, M. Rafelski, C. Villforth
Physics and Astronomy Faculty Publications
We study the relationship between the structure and star formation rate (SFR) of X-ray selected low and moderate luminosity active galactic nuclei (AGNs) in the two Chandra Deep Fields, using Hubble Space Telescope imaging from the Cosmic Assembly Near Infrared Extragalactic Legacy Survey (CANDELS) and deep far-infrared maps from the PEP+GOODS-Herschel survey. We derive detailed distributions of structural parameters and FIR luminosities from carefully constructed control samples of galaxies, which we then compare to those of the AGNs. At z ~ 1, AGNs show slightly diskier light profiles than massive inactive (non-AGN) galaxies, as well as modestly higher levels …
Candels/Goods-S, Cdfs, And Ecdfs: Photometric Redshifts For Normal And X-Ray-Detected Galaxies, Li-Ting Hsu, Mara Salvato, Kirpal Nandra, Marcella Brusa, Ralf Bender, Johannes Buchner, Jennifer L. Dooley, Dale D. Kocevski, Yicheng Guo, Nimish P. Hathi, Cyprian Rangel, S. P. Willner, Murray Brightman, Antonis Georgakakis, Tamás Budavári, Alexander S. Szalay, Matthew L.N. Ashby, Guillermo Barro, Tomas Dahlen, Sandra M. Faber, Henry C. Ferguson, Audrey Galametz, Andrea Grazian, Norman A. Grogin, Kuang-Han Huang, Anton M. Koekemoer, Ray A. Lucas, Elizabeth Mcgrath, Bahram Mobasher, Michael Peth, David J. Rosario, Jonathan R. Trump
Candels/Goods-S, Cdfs, And Ecdfs: Photometric Redshifts For Normal And X-Ray-Detected Galaxies, Li-Ting Hsu, Mara Salvato, Kirpal Nandra, Marcella Brusa, Ralf Bender, Johannes Buchner, Jennifer L. Dooley, Dale D. Kocevski, Yicheng Guo, Nimish P. Hathi, Cyprian Rangel, S. P. Willner, Murray Brightman, Antonis Georgakakis, Tamás Budavári, Alexander S. Szalay, Matthew L.N. Ashby, Guillermo Barro, Tomas Dahlen, Sandra M. Faber, Henry C. Ferguson, Audrey Galametz, Andrea Grazian, Norman A. Grogin, Kuang-Han Huang, Anton M. Koekemoer, Ray A. Lucas, Elizabeth Mcgrath, Bahram Mobasher, Michael Peth, David J. Rosario, Jonathan R. Trump
Physics and Astronomy Faculty Publications
We present photometric redshifts and associated probability distributions for all detected sources in the Extended Chandra Deep Field South (ECDFS). This work makes use of the most up-to-date data from the Cosmic Assembly Near-IR Deep Legacy Survey (CANDELS) and the Taiwan ECDFS Near-Infrared Survey (TENIS) in addition to other data. We also revisit multi-wavelength counterparts for published X-ray sources from the 4 Ms CDFS and 250 ks ECDFS surveys, finding reliable counterparts for 1207 out of 1259 sources (~96%). Data used for photometric redshifts include intermediate-band photometry deblended using the TFIT method, which is used for the first time in …
Electron Cooling In A Young Radio Supernova: Sn 2012aw, Naveen Yadav, Alak Ray, Christopher Stockdale, Poonam Chandrasiri, Randall Smith, Rupak Roy, Vikram Dwarkadas, Firoza Sutaria, David Pooley
Electron Cooling In A Young Radio Supernova: Sn 2012aw, Naveen Yadav, Alak Ray, Christopher Stockdale, Poonam Chandrasiri, Randall Smith, Rupak Roy, Vikram Dwarkadas, Firoza Sutaria, David Pooley
Physics Faculty Research and Publications
We present the radio observations and modeling of an optically bright Type II-P supernova (SN), SN 2012aw which exploded in the nearby galaxy Messier 95 (M95) at a distance of 10 Mpc. The spectral index values calculated using C, X, and K bands are smaller than the expected values for the optically thin regime. During this time, the optical bolometric light curve stays in the plateau phase. We interpret the low spectral-index values to be a result of electron cooling. On the basis of comparison between the Compton cooling timescale and the synchrotron cooling timescale, we find that …
Megamaser Detection And Nuclear Obscuration In Seyfert Galaxies, M. Ramolla, M. Hass, V. N. Bennert, R. Chini
Megamaser Detection And Nuclear Obscuration In Seyfert Galaxies, M. Ramolla, M. Hass, V. N. Bennert, R. Chini
Physics
We revisit the relation between H2O maser detection rate and nuclear obscuration for a sample of 114 Seyfert galaxies drawn from the CfA, 12 μm, and IRAS F25/F60 catalogs. These sources have mid-infrared spectra from the Spitzer Space Telescope and we search for accompanying X-ray and [O III] 5007 Å fluxes from the literature. We use the strength of the [O IV] 25.9 μm emission line as a tracer of the intrinsic AGN strength. After the normalization by [O IV], the observed X-ray flux provides information about X-ray absorption. The distribution of X-ray/[O IV] flux ratios …
Scaling Relations And Overabundance Of Massive Clusters At Z ≳ 1 From Weak-Lensing Studies With The Hubble Space Telescope, M J. Jee, Ks Dawson, H Hoekstra, S Perlmutter, P Rosati, M Brodwin, N Sukuzi, B Koester, M Postman, L Lubin, J Meyers, Sa Stanford, K Barbary, F Barrientos, P Eisenhardt, Hc Ford, Dg Gibank, Md Gladders, A Gonzalez, Dw Harris, Xiaosheng Huang, C Lidman, Es Rykoff, D Rubin, Al Spadafora
Scaling Relations And Overabundance Of Massive Clusters At Z ≳ 1 From Weak-Lensing Studies With The Hubble Space Telescope, M J. Jee, Ks Dawson, H Hoekstra, S Perlmutter, P Rosati, M Brodwin, N Sukuzi, B Koester, M Postman, L Lubin, J Meyers, Sa Stanford, K Barbary, F Barrientos, P Eisenhardt, Hc Ford, Dg Gibank, Md Gladders, A Gonzalez, Dw Harris, Xiaosheng Huang, C Lidman, Es Rykoff, D Rubin, Al Spadafora
Physics and Astronomy
We present weak gravitational lensing analysis of 22 high-redshift (z 1) clusters based on Hubble Space Telescope images. Most clusters in our sample provide significant lensing signals and are well detected in their reconstructed two-dimensional mass maps. Combining the current results and our previous weak-lensing studies of five other high-z clusters, we compare gravitational lensing masses of these clusters with other observables. We revisit the question whether the presence of the most massive clusters in our sample is in tension with the current ΛCDM structure formation paradigm. We find that the lensing masses are tightly correlated with the …
Measured Optical Constants Of Copper From 10 Nm To 35 Nm, David D. Allred, Nicole Brimhall, Nicholas Herrick, Justin Peatross, R. Steven Turley, Michael Ware
Measured Optical Constants Of Copper From 10 Nm To 35 Nm, David D. Allred, Nicole Brimhall, Nicholas Herrick, Justin Peatross, R. Steven Turley, Michael Ware
Faculty Publications
We use laser high-order harmonics and a polarization-ratioreflectance technique to determine the optical constants of copper and oxidized copper in the wavelength range 10-35 nm. This measurement resolves previously conflicting data sets, where disagreement on optical constants of copper in the extreme ultraviolet most likely arises from inadvertent oxidation of samples before measurement.
Development Of A Source Of Quasi-Monochromatic Mev Energy Photons, Donald Umstadter, Sudeep Banerjee, Viswanathan Ramanathan, Nathan D. Powers, Nathaniel Cunningham, Nathan A. Chandler-Smith
Development Of A Source Of Quasi-Monochromatic Mev Energy Photons, Donald Umstadter, Sudeep Banerjee, Viswanathan Ramanathan, Nathan D. Powers, Nathaniel Cunningham, Nathan A. Chandler-Smith
Donald Umstadter Publications
We report current progress on a project to develop an all-optically-driven x-ray photon source. A laser pulse with 40-50 TW of peak power is focused on a supersonic helium nozzle to drive a relativistic plasma wave. Electron beams with energies of 320 MeV (+/- 28 MeV) are accelerated by means of laser wakefield acceleration. Remarkably, the acceleration region is only 3 mm in length. This accelerator is currently being employed to demonstrate the generation of MeV- energy x-ray by means of all-optical Thomson scattering. By this mechanism, a lower power, laser pulse (from the same laser system) is focused onto …
Multiwavelength Monitoring Of The Narrow-Line Seyfert 1 Galaxy Arakelian 564. Iii. Optical Observations And The Optical--Uv--X-Ray Connection, O. Shemmer, P. Romano, R. Bertram, W. Brinkmann, S. Collier, K. A. Crowley, E. Detsis, A. V. Filippenko, C. Martin Gaskell, T. A. George, M. Gliozzi, M. E. Hiller, T. L. Jewell, Shai Kaspi, Elizabeth S. Klimek, M. H. Lannon, W D. Li, P. Martini, Smita Mathur, H. Negoro, Hagai Netzer, Iossif Papadakis, Ioannis Papamastorakis, Bradley M. Peterson, Bradley W. Peterson, Richard William Pogge, V. I. Pronik, Kenneth S. Rumstay, S. G. Sergeev, G. M. Stirpe, C. J. Taylor, R. R. Treffers, T. J. Turner, P. Uttley, Marianne Vestergaard, Kaspar Von Braun, R. M. Wagner, Z. Zheng
Multiwavelength Monitoring Of The Narrow-Line Seyfert 1 Galaxy Arakelian 564. Iii. Optical Observations And The Optical--Uv--X-Ray Connection, O. Shemmer, P. Romano, R. Bertram, W. Brinkmann, S. Collier, K. A. Crowley, E. Detsis, A. V. Filippenko, C. Martin Gaskell, T. A. George, M. Gliozzi, M. E. Hiller, T. L. Jewell, Shai Kaspi, Elizabeth S. Klimek, M. H. Lannon, W D. Li, P. Martini, Smita Mathur, H. Negoro, Hagai Netzer, Iossif Papadakis, Ioannis Papamastorakis, Bradley M. Peterson, Bradley W. Peterson, Richard William Pogge, V. I. Pronik, Kenneth S. Rumstay, S. G. Sergeev, G. M. Stirpe, C. J. Taylor, R. R. Treffers, T. J. Turner, P. Uttley, Marianne Vestergaard, Kaspar Von Braun, R. M. Wagner, Z. Zheng
Department of Physics and Astronomy: Faculty Publications
We present the results of a 2 yr long optical monitoring program of the narrow-line Seyfert 1 galaxy Ark 564. The majority of this monitoring project was also covered by X-ray observations (RXT E), and for a period of ~50 days, we observed the galaxy in UV (HST) and X-rays (RXTE and ASCA) simultaneously with the ground-based observations. Rapid and large-amplitude variations seen in the X-ray band, on a daily and hourly timescale, were not detected at optical and UV wavelengths, which in turn exhibited much lower variability either on short (1 day) or long (several months) timescales. The only …
Inhibition Of The Aminopeptidase From Aeromonas Proteolytica By L-Leucinephosphonic Acid. Spectroscopic And Crystallographic Characterization Of The Transition State Of Peptide Hydrolysis, Carin Stamper, Brian Bennett, Tanya Edwards, Richard C. Holz, Dagmar Ringe, Gregory A. Petsko
Inhibition Of The Aminopeptidase From Aeromonas Proteolytica By L-Leucinephosphonic Acid. Spectroscopic And Crystallographic Characterization Of The Transition State Of Peptide Hydrolysis, Carin Stamper, Brian Bennett, Tanya Edwards, Richard C. Holz, Dagmar Ringe, Gregory A. Petsko
Physics Faculty Research and Publications
The nature of the interaction of the transition-state analogue inhibitor l-leucinephosphonic acid (LPA) with the leucine aminopeptidase from Aeromonas proteolytica (AAP) was investigated. LPA was shown to be a competitive inhibitor at pH 8.0 with a Ki of 6.6 μM. Electronic absorption spectra, recorded at pH 7.5 of [CoCo(AAP)], [CoZn(AAP)], and [ZnCo(AAP)] upon addition of LPA suggest that LPA interacts with both metal ions in the dinuclear active site. EPR studies on the Co(II)-substituted forms of AAP revealed that the environments of the Co(II) ions in both [CoZn(AAP)] and [ZnCo(AAP)] become highly asymmetric and constrained upon the addition of …
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 …