40,673 research outputs found
Broad-line and Multi-wave Band Emission from Blazars
We study the correlations of the flux of the broad-line emission ()
with the X-ray emission flux, optical emission flux at 5500 \AA and radio
emission flux at 5 GHz, respectively, for a large sample of 50 Blazars (39
flat-spectrum radio quasars (FSRQs) and 11 BL Lac objects). Our main results
are as follows. There are very strong correlations between and
and between and in both states for 39 FSRQs and the
slopes of the linear regression equations are almost equal to 1. There are weak
correlations between and and between and
for 11 BL Lac objects in both states, and the slopes of the linear regression
equations are close to 1. There are significant correlations between
and and between and for 50 blazars in both states,
the slopes of both the linear regression equations are also close to 1. These
results support a close link between relativistic jets and accretion on to the
central Kerr black hole. On the other hand, we find that BL Lac objects have
low accretion efficiency , whereas FSRQs have high accretion efficiency
. The unified model of FSRQs and BL Lac objects is also discussed.Comment: 15 pages, 8 figure
Effect of chain stiffness on ion distributions around a polyelectrolyte in multivalent salt solutions
Ion distributions in dilute polyelectrolyte solutions are studied by means of
Langevin dynamics simulations. We show that the distributions depend on the
conformation of a chain while the conformation is determined by the chain
stiffness and the salt concentration. We observe that the monovalent
counterions originally condensed on a chain can be replaced by the multivalent
ones dissociated from the added salt due to strong electrostatic interaction.
These newly condensed ions give an important impact on the chain structure. At
low and at high salt concentrations, the conformation of a semiflexible chain
is rodlike. The ion distributions show similarity to those for a rigid chain,
but difference to those for a flexible chain whose conformation is a coil. In
the mid-salt region, the flexible chain and the semiflexible chain collapse but
the collapsed chain structures are, respectively, disordered and ordered
structures. The ion distributions hence show different profiles for these three
chain stiffness with the curves for the semiflexible chain lying between those
for the flexible and the rigid chains. The number of the condensed multivalent
counterions, as well as the effective chain charge, also shows similar
behavior, demonstrating a direct connection with the chain morphology.
Moreover, we find that the condensed multivalent counterions form triplets with
two adjacent monomers and are localized on the chain axis at intermediate salt
concentration when the chain stiffness is semiflexible or rigid. The
microscopic information obtained here provides valuable insight to the
phenomena of DNA condensation and is very useful for researchers to develop new
models.Comment: 28 pages, 10 figures, accepted for publication in JC
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