5,462 research outputs found
NuSTAR hard X-ray data and Gemini 3D spectra reveal powerful AGN and outflow histories in two low-redshift Lyman- blobs
We have shown that Lyman- blobs (LABs) may still exist even at
, about 7 billion years later than most other LABs known (Schirmer et
al. 2016). Their luminous Ly and [OIII] emitters at offer
new insights into the ionization mechanism. This paper focuses on the two X-ray
brightest LABs at , SDSS J01130106 (J0113) and SDSS J11550147
(J1155), comparable in size and luminosity to `B1', one of the best-studied
LABs at 2. Our NuSTAR hard X-ray (3--30 keV) observations reveal
powerful active galactic nuclei (AGN) with -- erg cm s. J0113 also faded by a
factor of between 2014 and 2016, emphasizing that variable AGN may
cause apparent ionization deficits in LABs. Joint spectral analyses including
Chandra data constrain column densities of cm (J0113) and cm (J1155). J0113 is likely buried in
a torus with a narrow ionization cone, but ionizing radiation is also leaking
in other directions as revealed by our Gemini/GMOS 3D spectroscopy. The latter
shows a bipolar outflow over kpc, with a peculiar velocity profile that is
best explained by AGN flickering. X-ray analysis of J1155 reveals a weakly
absorbed AGN that may ionize over a wide solid angle, consistent with our 3D
spectra. Extinction corrected [OIII] log-luminosities are high, . The
velocity dispersions are low, -- km s, even at the AGN
positions. We argue that this is a combination of high extinction hiding the
turbulent gas, and previous outflows that have cleared the escape paths for
their successors.Comment: 15 pages, 17 Figures, accepted for publication in Ap
Abstracts of the Fifth North American Echinoderm Conference, Melbourne, Florida, 20-25 July 2008
These abstracts represent research studies presented at the Fifth North American Echinoderm Conference (NAEC) sponsored by the Florida Institute of Technology and the University of Alabama at Birmingham, 20-25 July 2008. The meeting was held on the campus of the Florida Institute of Technology in Melbourne, FL. Those attending the conference were gathered in large part to recognize the outstanding past, present, and future career of John M. Lawrence (see abstract by J. S. Pearse), the quintessential echinoderm biologist. We wish to thank Carolyn Wood (Assistant Editor) and Monty Graham (Editor) for facilitating publication in Gulf of Mexico Science
Dense gas and HII regions in the starburst galaxy NGC 253
The energetic activity in the nuclear barred region of NGC 253 is attributable to a burst of star formation. NGC 253 is in many ways a twin of the prototypical starburst galaxy M82; the strong non-thermal radio continuum, high far-infrared luminosity, and bright molecular emission of the central 1 Kpc parallel the morphology of the M82 starburst. Furthermore, the filamentary low ionization optical emission and extended x ray emission along the minor axis in NGC 253 is similar to a scaled down version of the well developed galactic bipolar wind in M82. The infrared luminosity of NGC 253, 3(exp 10) solar luminosity, is comparable to M82 but is emitted from a smaller region (Telesco and Harper 1980). This suggests that the NGC 253 starburst may be more intense and at an earlier evolutionary stage than M82. However, the presence of a non-stellar AGN in NGC 253 may complicate the comparison (Turner and Ho, 1985). Researchers used the Hat Creek millimeter interferometer to map emission from the J = 1 to 0 transitions of HCN and HCO(+) as well as 3 mm continuum emission, toward the nuclear region of NGC 253. The HCO(+) and continuum observations are sensitive to spatial scales from 6 to 45 seconds. The 2 minute field of view comfortably includes the entire starburst region (about 40 seconds; 650 pc). Because the longer baseline HCN observations are not yet complete, they are only sensitive to spatial scales from 15 to 45 seconds
Intelligent Queries over BIRN Data using the Foundational Model of Anatomy and a Distributed Query-Based Data Integration System
We demonstrate the usefulness of the Foundational Model of Anatomy (FMA) ontology in reconciling different neuroanatomical parcellation schemes in order to facilitate automatic annotation and “intelligent” querying and visualization over a large multisite fMRI study of schizophrenic versus normal controls
Enabling RadLex with the Foundational Model of Anatomy Ontology to Organize and Integrate Neuro-imaging Data
In this study we focused on empowering RadLex with an ontological framework and additional content derived from the Foundational Model of Anatomy Ontology1 thereby providing RadLex the facility to correlate the different standards used in annotating neuroradiological image data. The objective of this work is to promote data sharing, data harmonization and interoperability between disparate neuroradiological labeling systems
Finite element approximation of an optimal control problem for the von Karman equations
This paper is concerned with optimal control problems for the von Karman equations with distributed controls. We first show that optimal solutions exist. We then show that Lagrange multipliers may be used to enforce the constraints and derive an optimality system from which optimal states and controls may be deduced. Finally we define finite element approximations of solutions for the optimality system and derive error estimates for the approximations
The Agent Institute: Develop an Infrastructure for Agent-Based Research and Development for the State of Maine
This award provides support to establish The Agent Institute (AI), an organization anticipated to become self-sustaining and generally enhance research and development for the State of Maine. The AI will promote interactions between industry and foster computer-technology research, specifically in software development and software-hardware relationships in the area of robotics. Industrial applications in extreme or hazardous environments will be emphasized because agent-based systems are designed to read/sense environmental information, make decisions, and take actions based on the information sensed and processed. The award provides an initial two years of salary support to hire an executive director and an administrative assistant. These individuals will be responsible for developing a series of workshops designed to bring researchers and developers with interests and expertise in agent-based systems together in collaborative projects. Education and outreach efforts will also be part of the AI\u27s mission to bring knowledge about this area to K-12 educators and schools with the goal of encouraging students toward careers in agent-based systems and high technology in general
Multisegment Scheme Applications to Modified Chebyshev Picard Iteration Method for Highly Elliptical Orbits
A modified Chebyshev Picard iteration method is proposed for solving orbit propagation initial/boundary value problems. Cosine sampling techniques, known as Chebyshev-Gauss-Lobatto (CGL) nodes, are used to reduce Runge’s phenomenon that plagues many series approximations.
The key benefit of using the CGL data sampling is that the nodal points are distributed
nonuniformly, with dense sampling at the beginning and ending times. This problem can be addressed
by a nonlinear time transformation and/or by utilizing multiple time segments over an
orbit. This paper suggests a method, called a multisegment method, to obtain accurate solutions
overall regardless of initial states and albeit eccentricity by dividing the given orbit into two or
more segments based on the true anomaly
Through a Lens Darkly: Evidence for Dusty Gravitational Lenses
Foreground galaxies that amplify the light from background quasars may also
dim that light if the galaxies contain enough dust. Extinction by dust in
lenses could hide the large number of lensed systems predicted for a flat
universe with a large value of the cosmological constant . We look for
one signature of dust, namely reddening, by examining optical-infrared colors
of gravitationally lensed images of quasars. We find that the lensed systems
identified in radio and infrared searches have redder optical-IR colors than
optically selected ones. This could be due to a bias against selecting reddened
(hence extincted) quasars in the optical surveys, or due to the differences in
the intrinsic colors of optical and radio quasars. Comparison of the
radio-selected lensed and unlensed quasars shows that the lensed ones have
redder colors. We therefore conclude that at least part of the color difference
between the two lens samples is due to dust.
From the color difference between lensed and unlensed radio quasars (and
assuming Galactic extinction law) we can reconcile a large cosmological
constant () with the number of lensed systems observed in flux
limited optical surveys. These results substantially weaken the strongest
constraint on cosmological scenarios that invoke a non-zero cosmological
constant to explain age discrepancy problems, satisfy predictions of
inflationary models of the early universe and play a role in large scale
structure formation models. They also raise the prospect of using gravitational
lenses to study the interstellar medium in high redshift galaxies.Comment: Sumitted to MNRAS, 6 pages, 3 figures. Also available at
http://www.astro.princeton.edu/~san/Abstracts/dusty.htm
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