10 research outputs found
Weak field limit of Reissner-Nordstrom black hole lensing
We study gravitational lensing by a Reissner-Nordstrom (RN) black hole in the
weak field limit. We obtain the basic equations for the deflection angle and
time delay and find analytical expressions for the positions and amplifications
of the primary and secondary images. Due to a net positive charge, the
separation between images increases, but no change in the total magnification
occurs.Comment: 8 pages, to appear in Phys. Rev.
Super star clusters and Supernovae in interacting LIRGs unmasked by NIR adaptive optics
We report on an on-going near-IR adaptive optics survey targeting interacting
luminous IR galaxies. High-spatial resolution NIR data are crucial to enable
interpretation of kinematic, dynamical and star formation (SF) properties of
these very dusty objects. Whole progenitor nuclei in the interactions can be
missed if only optical HST imaging is used. Here we specifically present the
latest results regarding core-collapse supernovae found within the highly
extincted nuclear regions of these galaxies. Direct detection and study of such
highly obscured CCSNe is crucial for revising the optically-derived SN rates
used for providing an independent measurement of the SF history of the
Universe. We also present thus-far the first NIR luminosity functions of super
star cluster (SSC) candidates. The LFs can then be used to constrain the
formation and evolution of SSCs via constraints based on initial mass functions
and cluster disruption models.Comment: 6 pages. To appear in proceedings of 'Galaxies and their Masks'
(Namibia, April 2010), published by Springer, New York, eds. D.L. Block, K.C.
Freeman, I. Puerar
"Low-state" Black Hole Accretion in Nearby Galaxies
I summarize the main observational properties of low-luminosity AGNs in
nearby galaxies to argue that they are the high-mass analogs of black hole
X-ray binaries in the "low/hard" state. The principal characteristics of
low-state AGNs can be accommodated with a scenario in which the central engine
is comprised of three components: an optically thick, geometrically accretion
disk with a truncated inner radius, a radiatively inefficient flow, and a
compact jet.Comment: 8 pages. To appear in From X-ray Binaries to Quasars: Black Hole
Accretion on All Mass Scales, ed. T. J. Maccarone, R. P. Fender, and L. C. Ho
(Dordrecht: Kluwer
'Disc-jet' coupling in black hole X-ray binaries and active galactic nuclei
In this chapter I will review the status of our phenomenological
understanding of the relation between accretion and outflows in accreting black
hole systems. This understanding arises primarily from observing the relation
between X-ray and longer wavelength (infrared, radio) emission. The view is
necessarily a biased one, beginning with observations of X-ray binary systems,
and attempting to see if they match with the general observational properties
of active galactic nuclei.Comment: 28 pages, 15 figures, To appear in Belloni, T. (ed.): The Jet
Paradigm - From Microquasars to Quasars, Lect. Notes Phys. 794 (2009
Host Plant Records for Fruit Flies (Diptera: Tephritidae: Dacini) in the Pacific Islands: 2. Infestation Statistics on Economic Hosts
Detailed host records are listed for 39 species of Bactrocera and 2 species of Dacus fruit flies, infesting 98 species of commercial and edible fruits in the Pacific Island Countries and Territories, based on sampling and incubating in laboratory almost 13,000 field collected samples, or over 380,000 fruits. For each host-fly-country association, quantitative data are presented on the weight and number of fruits collected, the proportion of infested samples, the number of adult flies emerged per kg of fruits and, whenever available, the percentage of individual fruits infested. All the published records of each fly-host-country association are cited and erroneous or dubious published records are rectified or commented. Laboratory forced infestation data are also cited and reviewed