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Full-Text Articles in Physics
Agn Dusty Tori. I. Handling Of Clumpy Media, Maia Nenkova, Matthew M. Sirocky, Željko Ivezić, Moshe Elitzur
Agn Dusty Tori. I. Handling Of Clumpy Media, Maia Nenkova, Matthew M. Sirocky, Željko Ivezić, Moshe Elitzur
Physics and Astronomy Faculty Publications
According to unified schemes of active galactic nuclei (AGNs), the central engine is surrounded by dusty, optically thick clouds in a toroidal structure. We have recently developed a formalism that for the first time takes proper account of the clumpy nature of the AGN torus. We now provide a detailed report of our findings in a two-paper series. Here we present our general formalism for radiative transfer in clumpy media and construct its building blocks for the AGN problem-the source functions of individual dusty clouds heated by the AGN radiation field. We show that a fundamental difference from smooth density …
Silicates In Ultraluminous Infrared Galaxies, M. M. Sirocky, N. A. Levenson, Moshe Elitzur, H. W. W. Spoon, L. Armus
Silicates In Ultraluminous Infrared Galaxies, M. M. Sirocky, N. A. Levenson, Moshe Elitzur, H. W. W. Spoon, L. Armus
Physics and Astronomy Faculty Publications
We analyze the mid-infrared (MIR) spectra of ultraluminous infrared galaxies (ULIRGs) observed with the Spitzer Space Telescope's Infrared Spectrograph. Dust emission dominates the MIR spectra of ULIRGs, and the reprocessed radiation that emerges is independent of the underlying heating spectrum. Instead, the resulting emission depends sensitively on the geometric distribution of the dust, which we diagnose with comparisons of numerical simulations of radiative transfer. Quantifying the silicate emission and absorption features that appear near 10 and 18 μm requires a reliable determination of the continuum, and we demonstrate that including …
The Effect Of 53 ΜM Ir Radiation On 18 Cm Oh Megamaser Emission, Philip Lockett, Moshe Elitzur
The Effect Of 53 ΜM Ir Radiation On 18 Cm Oh Megamaser Emission, Philip Lockett, Moshe Elitzur
Physics and Astronomy Faculty Publications
OH megamasers (OHMs) emit primarily in the main lines at 1667 and 1665 MHz and differ from their Galactic counterparts due to their immense luminosities, large line widths, and 1667/1665 MHz flux ratios, which are always greater than 1. We find that these maser properties result from strong 53 μm radiative pumping combined with line overlap effects caused by turbulent line widths ~20 km s-1 pumping calculations that do not include line overlap are unreliable. A minimum dust temperature of ~45 K is needed for inversion, and maximum maser efficiency occurs for dust temperatures ~80-140 K. We find …