1,066 research outputs found
On Lelong Numbers of Generalized Monge-Amp\`ere Products
We consider generalized (mixed) Monge-Amp\`ere products of
quasiplurisubharmonic functions (with and without analytic singularities) as
they were introduced and studied in several articles written by subsets of M.
Andersson, E. Wulcan, Z. B{\l}ocki, R. L\"ark\"ang, H. Raufi, J. Ruppenthal,
and the author. We continue these studies and present estimates for the Lelong
numbers of pushforwards of such products by proper holomorphic submersions.
Furthermore, we apply these estimates to Chern and Segre currents of
pseudoeffective vector bundles. Among other corollaries, we obtain the
following generalization of a recent result by X. Wu. If the non-nef locus of a
pseudoeffective vector bundle on a K\"ahler manifold is contained in a
countable union of -codimensional analytic sets, and if the -power of the
first Chern class of is trivial, then is nef.Comment: 32 pages; minor corrections in the second versio
What is the Hidden Depolarization Mechanism in Low Luminosity AGN?
Millimeter wavelength polarimetry of accreting black hole systems can provide
a tomographic probe of the accretion flow on a wide range of linear scales. We
searched for linear polarization in two low luminosity active galactic nuclei
(LLAGN), M81 and M84, using the Combined Array for Millimeter Astronomy (CARMA)
and the Submillimeter Array (SMA). We find upper limits of
averaging over the full bandwidth and with a rotation measure (RM) synthesis
technique. These low polarization fractions, along with similar low values for
LLAGN M87 and 3C84, suggest that LLAGN have qualitatively different
polarization properties than radio-loud sources and Sgr A*. If the sources are
intrinsically polarized and then depolarized by Faraday rotation then we place
lower limits on the RM of a few times for the full
bandwidth case and for the RM synthesis
analysis. These limits are inconsistent with or marginally consistent with
expected accretion flow properties. Alternatively, the sources may be
depolarized by cold electrons within a few Schwarzschild radii from the black
hole, as suggested by numerical models.Comment: Accepted for publication in ApJ
Determining the optimal locations for shock acceleration in magnetohydrodynamical jets
Observations of relativistic jets from black holes systems suggest that
particle acceleration often occurs at fixed locations within the flow. These
sites could be associated with critical points that allow the formation of
standing shock regions, such as the magnetosonic modified fast point. Using the
self-similar formulation of special relativistic magnetohydrodynamics by
Vlahakis & K\"onigl, we derive a new class of flow solutions that are both
relativistic and cross the modified fast point at a finite height. Our
solutions span a range of Lorentz factors up to at least 10, appropriate for
most jets in X-ray binaries and active galactic nuclei, and a range in injected
particle internal energy. A broad range of solutions exists, which will allow
the eventual matching of these scale-free models to physical boundary
conditions in the analysis of observed sources.Comment: 9 pages, 4 figures, accepted for publication in Ap
The Fundamental Plane of Black Hole Accretion and its Use as a Black Hole-Mass Estimator
We present an analysis of the fundamental plane of black hole accretion, an
empirical correlation of the mass of a black hole (), its 5 GHz radio
continuum luminosity (), and its 2-10 keV X-ray power-law
continuum luminosity (). We compile a sample of black holes with primary,
direct black hole-mass measurements that also have sensitive,
high-spatial-resolution radio and X-ray data. Taking into account a number of
systematic sources of uncertainty and their correlations with the measurements,
we use Markov chain Monte Carlo methods to fit a mass-predictor function of the
form . Our best-fit results are , , and
with the natural logarithm of the Gaussian intrinsic scatter in the log-mass
direction . This result is a
significant improvement over our earlier mass scaling result because of the
increase in active galactic nuclei sample size (from 18 to 30), improvement in
our X-ray binary sample selection, better identification of Seyferts, and
improvements in our analysis that takes into account systematic uncertainties
and correlated uncertainties. Because of these significant improvements, we are
able to consider potential influences on our sample by including all sources
with compact radio and X-ray emission but ultimately conclude that the
fundamental plane can empirically describe all such sources. We end with advice
for how to use this as a tool for estimating black hole masses.Comment: ApJ Accepted. Online interactive version of Figure 7 available at
http://kayhan.astro.lsa.umich.edu/supplementary_material/fp
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