60,742 research outputs found
Long-term in situ observations on typhoon-triggered turbidity currents in the deep sea
This work is supported by the National Science Foundation of China (grants 91528304, 41576005, and 41530964). We thank J. Li, X. Lyu, P. Li, K. Duan, J. Ronan, Y. Wang, P. Ma, and Y. Li for cruise assistance; G. de Lange and J. Hinojosa for editing an early version of manuscript; and E. Pope and two anonymous reviewers for their reviews.Peer reviewedPublisher PD
Singularities of determinantal pure pairs
Let be a generic determinantal affine variety over a perfect field of
characteristic and be a standard prime divisor
generator of . We prove that the pair
is purely -regular if and so that is purely log terminal (PLT)
if and is log -Gorenstein. In general, using recent
results of Z. Zhuang and S. Lyu, we show that is of PLT-type, i.e.
there is a -divisor with coefficients in such that
is PLT.Comment: 23 pages, minor corrections, final version, accepted for publication
at the Bollettino dell'Unione Matematica Italian
On Properties of Random Binary Contingency Tables with Non-Uniform Margin
We study the random binary contingency tables with non-uniform margin. More
precisely, for parameters , we consider the random binary contingency tables whose first
rows and columns have margin and the rest columns and rows
have margin . We study various asymptotic properties of as . Our treatment follows closely the recent paper of Dittmer-Lyu-Pak and
this answers a question posted by Barvinok.Comment: 15 pages. Minor chang
The Intrinsic Far-infrared Continua of Type-1 Quasars
The range of currently proposed active galactic nucleus (AGN) far-infrared
templates results in uncertainties in retrieving host galaxy information from
infrared observations and also undermines constraints on the outer part of the
AGN torus. We discuss how to test and reconcile these templates. Physically,
the fraction of the intrinsic AGN IR-processed luminosity compared with that
from the central engine should be consistent with the dust-covering factor. In
addition, besides reproducing the composite spectral energy distributions
(SEDs) of quasars, a correct AGN IR template combined with an accurate library
of star-forming galaxy templates should be able to reproduce the IR properties
of the host galaxies, such as the luminosity-dependent SED shapes and aromatic
feature strengths. We develop tests based on these expected behaviors and find
that the shape of the AGN intrinsic far-IR emission drops off rapidly starting
at m and can be matched by an Elvis et al. (1994)-like template
with minor modification. Despite the variations in the near- to mid-IR bands,
AGNs in quasars and Seyfert galaxies have remarkably similar intrinsic far-IR
SEDs at - m, suggesting similar emission character of
the outermost region of the circumnuclear torus. The variations of the
intrinsic AGN IR SEDs among the type-1 quasar population can be explained by
the changing relative strengths of four major dust components with similar
characteristic temperatures, and there is evidence for compact AGN-heated dusty
structures at sub-kpc scales in the far-IR.Comment: Minor corrections to match the published version, 14 pages, 9
figures, 5 tables. The quasar intrinsic IR templates can be found at
http://u.arizona.edu/~jianwei/data/AGN_temp.ascii or in the published pape
Polar Dust, Nuclear Obscuration and IR SED Diversity in Type-1 AGNs
Despite the hypothesized similar face-on viewing angles, the infrared
emission of type-1 AGNs has diverse spectral energy distribution (SED) shapes
that deviate substantially from the well-characterized quasar templates.
Motivated by the commonly-seen UV-optical obscuration and the discovery of
parsec-scale mid-IR polar dust emission in some nearby AGNs, we develop
semi-empirical SED libraries for reddened type-1 AGNs built on the quasar
intrinsic templates, assuming low-level extinction caused by an extended
distribution of large dust grains. We demonstrate that this model can reproduce
the nuclear UV-to-IR SED and the strong mid-IR polar dust emission of NGC 3783,
the type-1 AGN with the most relevant and robust observational constraints. In
addition, we compile 64 low- Seyfert-1 nuclei with negligible mid-IR star
formation contamination and satisfactorily fit the individual IR SEDs as well
as the composite UV to mid-IR composite SEDs. Given the success of these fits,
we characterize the possible infrared SED of AGN polar dust emission and
utilize a simple but effective strategy to infer its prevalence among type-1
AGNs. The SEDs of high- peculiar AGNs, including the extremely red quasars,
mid-IR warm-excess AGNs, and hot dust-obscured galaxies, can be also reproduced
by our model. These results indicate that the IR SEDs of most AGNs, regardless
of redshift or luminosity, arise from similar circumnuclear torus properties
but differ mainly due to the optical depths of extended obscuring dust
components.Comment: 37 pages, 22 figures, 5 tables; accepted for publication in The
Astrophysical Journal; the AGN templates can be retrieved from
https://github.com/karlan/AGN_template
- …