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Astrophysics and Astronomy

University of Missouri, St. Louis

2006

Articles 1 - 3 of 3

Full-Text Articles in Physics

[Accepted Article Manuscript Version (Postprint)] Testing The Inverse-Compton Catastrophe Scenario In The Intra-Day Variable Blazar S5 0716+71. I. Simultaneous Broadband Observations During November 2003, Bruce Wilking, L. Ostorero, S Wagner, J. Gracia, E. Ferrero, T Krichbaum, S. Britzen, A. Witzel, K. Nilsson, M. Villata, U. Bach, D. Barnaby, S. Bernhart, M Carini, C Chen, W. Chen, S. Ciprini, S. Crapanzano, V. Doroshenko, N Efimova, D. Emmanoulopoulos, L. Fuhrmann, K Gabanyi, A. Giltinan, V. Hagen-Thorn, M. Hauser, J. Heidt, A Hojaev, T. Hovatta, F. Hroch, M. Ibrahimov, V. Impellizzeri, R Ivanidze, D. Kachel, A. Kraus, O. Kurtanidze, A. Lähteenmäki, L. Lanteri, V. Larionov, Z Lin, E. Lindfors, F. Munz, M. Nikolashvili, G. Nucciarelli, A. O’Connor, J. Ohlert, M. Pasanen, C. Pullen, C. Raiteri, T Rector, R. Robb, L. Sigua, A. Sillanpää, L. Sixtova, N. Smith, P. Strub, S. Takahashi, L. Takalo, C. Tapken, J. Tartar, M. Tornikoski, G. Tosti, M. Tröller, R. Walters, W. Wills, I. Agudo, H. Aller, M. Aller, E. Angelakis, J. Klare, E. Körding, R Strom, H. Teräsranta, H. Ungerechts, B. Vila-Vilaró Jun 2006

[Accepted Article Manuscript Version (Postprint)] Testing The Inverse-Compton Catastrophe Scenario In The Intra-Day Variable Blazar S5 0716+71. I. Simultaneous Broadband Observations During November 2003, Bruce Wilking, L. Ostorero, S Wagner, J. Gracia, E. Ferrero, T Krichbaum, S. Britzen, A. Witzel, K. Nilsson, M. Villata, U. Bach, D. Barnaby, S. Bernhart, M Carini, C Chen, W. Chen, S. Ciprini, S. Crapanzano, V. Doroshenko, N Efimova, D. Emmanoulopoulos, L. Fuhrmann, K Gabanyi, A. Giltinan, V. Hagen-Thorn, M. Hauser, J. Heidt, A Hojaev, T. Hovatta, F. Hroch, M. Ibrahimov, V. Impellizzeri, R Ivanidze, D. Kachel, A. Kraus, O. Kurtanidze, A. Lähteenmäki, L. Lanteri, V. Larionov, Z Lin, E. Lindfors, F. Munz, M. Nikolashvili, G. Nucciarelli, A. O’Connor, J. Ohlert, M. Pasanen, C. Pullen, C. Raiteri, T Rector, R. Robb, L. Sigua, A. Sillanpää, L. Sixtova, N. Smith, P. Strub, S. Takahashi, L. Takalo, C. Tapken, J. Tartar, M. Tornikoski, G. Tosti, M. Tröller, R. Walters, W. Wills, I. Agudo, H. Aller, M. Aller, E. Angelakis, J. Klare, E. Körding, R Strom, H. Teräsranta, H. Ungerechts, B. Vila-Vilaró

Physics Faculty Works

Context. Some intra-day variable, compact extra-galactic radio sources show brightness temperatures severely exceeding 1012 K, the limit set by catastrophic inverse-Compton (IC) cooling in sources of incoherent synchrotron radiation. The violation of the IC limit, actually possible under non-stationary conditions, would lead to IC avalanches in the soft-γ-ray energy band during transient periods.Aims. For the first time, broadband signatures of possible IC catastrophes were searched for in a prototypical source, S5 0716+71.Methods. A multifrequency observing campaign targetting S5 0716+71 was carried out during November 06-20, 2003. The observations, organized under the framework of the European Network for the Investigation of …


The Shape Of Dark Matter Haloes: Dependence On Mass, Redshift, Radius And Formation, Ricardo Flores, Brandon Allgood, Joel Primack, Andrey Kravtsov, Risa Wechsler, Andreas Faltenbacher, James Bullock Apr 2006

The Shape Of Dark Matter Haloes: Dependence On Mass, Redshift, Radius And Formation, Ricardo Flores, Brandon Allgood, Joel Primack, Andrey Kravtsov, Risa Wechsler, Andreas Faltenbacher, James Bullock

Physics Faculty Works

Using six high-resolution dissipationless simulations with a varying box size in a flat Lambda cold dark matter (ΛCDM) universe, we study the mass and redshift dependence of dark matter halo shapes for Mvir= 9.0 × 1011− 2.0 × 1014h−1 M⊙, over the redshift range z= 0–3, and for two values of σ8= 0.75 and 0.9. Remarkably, we find that the redshift, mass and σ8 dependence of the mean smallest-to-largest axis ratio of haloes is well described by the simple power-law relation 〈s〉= (0.54 ± 0.02)(Mvir/M*)−0.050±0.003, where s is measured at 0.3Rvir, and the z and σ8 dependences are governed by …


Post-Outburst Infrared Spectra Of V1647 Ori, The Illuminating Star Of Mcneil's Nebula, Erika Gibb, T Rettig, S Brittain, D Wasikowski, Theodore Simon, William Vacca, Michael Cushing Apr 2006

Post-Outburst Infrared Spectra Of V1647 Ori, The Illuminating Star Of Mcneil's Nebula, Erika Gibb, T Rettig, S Brittain, D Wasikowski, Theodore Simon, William Vacca, Michael Cushing

Physics Faculty Works

V1647 Ori is a low-mass star in the L1630 star-forming region that underwent an outburst in late 2003 and early 2004. We present postoutburst infrared spectra obtained with NIRSPEC (Keck II) and SpeX (IRTF) and compare these to spectra taken during the outburst. The results show that the temperature of the hot CO formed in the inner part of the disk has declined by ~800 K, while the water and CO ice and low-J CO gas features remained unchanged, consistent with previous assertions that the latter, low-temperature features arise in the foreground cloud. The P Cygni profiles of the Paschen …