32,659 research outputs found
Fundamental Plane of Black Hole Activity in Quiescent Regime
A correlation among the radio luminosity (), X-ray luminosity
(), and black hole mass () in active galactic nuclei
(AGNs) and black hole binaries is known to exist and is called the "Fundamental
Plane" of black hole activity. Yuan & Cui (2005) predicts that the radio/X-ray
correlation index, , changes from to
when decreases below a
critical value . While many works favor such a change, there are
also several works claiming the opposite. In this paper, we gather from
literature a largest quiescent AGN (defined as ) sample to date, consisting of sources. We find that these
quiescent AGNs follow a radio/X-ray relationship, in
excellent agreement with the Yuan \& Cui prediction. The reason for the
discrepancy between the present result and some previous works is that their
samples contain not only quiescent sources but also "normal" ones (i.e.,
). In this case, the quiescent sources will
mix up with those normal ones in and . The value of
will then be between and , with the exact value
being determined by the sample composition, i.e., the fraction of the quiescent
and normal sources. Based on this result, we propose that a more physical way
to study the Fundamental Plane is to replace and with
and , respectively.Comment: 11 pages, 7 figures, accepted for publication in The Astrophysical
Journa
The tensor renormalization group study of the general spin-S Blume-Capel model
We focus on the special situation of of the general spin-S Blume-Capel
model on the square lattice. Under the infinitesimal external magnetic field,
the phase transition behaviors due to the thermal fluctuations are discussed by
the newly developed tensor renormalization group method. For the case of the
integer spin-S, the system will undergo first-order phase transitions with
the successive symmetry breaking with the magnetization . For the
half-integer spin-S, there are similar first order phase transition
with stepwise structure, in addition, there is a continuous
phase transition due to the spin-flip symmetry breaking. In the low
temperature regions, all first-order phase transitions are accompanied by the
successive disappearance of the optional spin-component pairs(),
furthermore, the critical temperature for the nth first-order phase transition
is the same, independent of the value of the spin-S. In the absence of the
magnetic field, the visualization parameter characterizing the intrinsic
degeneracy of the different phases clearly demonstrates the phase transition
process.Comment: 6 pages, 7 figure
Quantum Synchronizable Codes From Quadratic Residue Codes and Their Supercodes
Quantum synchronizable codes are quantum error-correcting codes designed to
correct the effects of both quantum noise and block synchronization errors.
While it is known that quantum synchronizable codes can be constructed from
cyclic codes that satisfy special properties, only a few classes of cyclic
codes have been proved to give promising quantum synchronizable codes. In this
paper, using quadratic residue codes and their supercodes, we give a simple
construction for quantum synchronizable codes whose synchronization
capabilities attain the upper bound. The method is applicable to cyclic codes
of prime length
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