60,637 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
Resurvey of order and chaos in spinning compact binaries
This paper is mainly devoted to applying the invariant, fast, Lyapunov
indicator to clarify some doubt regarding the apparently conflicting results of
chaos in spinning compact binaries at the second-order post-Newtonian
approximation of general relativity from previous literatures. It is shown with
a number of examples that no single physical parameter or initial condition can
be described as responsible for causing chaos, but a complicated combination of
all parameters and initial conditions is responsible. In other words, a
universal rule for the dependence of chaos on each parameter or initial
condition cannot be found in general. Chaos does not depend only on the mass
ratio, and the maximal spins do not necessarily bring the strongest effect of
chaos. Additionally, chaos does not always become drastic when the initial spin
vectors are nearly perpendicular to the orbital plane, and the alignment of
spins cannot trigger chaos by itself.Comment: 16 pages, 7 figure
An Ultra-Low-Power Oscillator with Temperature and Process Compensation for UHF RFID Transponder
This paper presents a 1.28MHz ultra-low-power oscillator with temperature and process compensation. It is very suitable for clock generation circuits used in ultra-high-frequency (UHF) radio-frequency identification (RFID) transponders. Detailed analysis of the oscillator design, including process and temperature compensation techniques are discussed. The circuit is designed using TSMC 0.18μm standard CMOS process and simulated with Spectre. Simulation results show that, without post-fabrication calibration or off-chip components, less than ±3% frequency variation is obtained from –40 to 85°C in three different process corners. Monte Carlo simulations have also been performed, and demonstrate a 3σ deviation of about 6%. The power for the proposed circuitry is only 1.18µW at 27°C
Distinguishing RBL-like objects and XBL-like objects with the peak emission frequency of the overall energy spectrum
We investigate quantitatively how the peak emission frequency of the overall
energy spectrum is at work in distinguishing RBL-like and XBL-like objects. We
employ the sample of Giommi et al. (1995) to study the distribution of BL
Lacertae objects with various locations of the cutoff of the overall energy
spectrum. We find that the sources with the cutoff located at lower frequency
are indeed sited in the RBL region of the plane,
while those with the cutoff located at higher frequency are distributed in the
XBL region. For a more quantitative study, we employ the BL Lacertae samples
presented by Sambruna et al. (1996), where, the peak emission frequency, , of each source is estimated by fitting the data with a parabolic function.
In the plot of we find that, in the four different
regions divided by the line and the line,
all the RBL-like objects are inside the upper left region, while most XBL-like
objects are within the lower right region. A few sources are located in the
lower left region. No sources are in the upper right region. This result is
rather quantitative. It provides an evidence supporting what Giommi et al.
(1995) suggested: RBL-like and XBL-like objects can be distinguished by the
difference of the peak emission frequency of the overall energy spectrum.Comment: 7 pages, 2 figure
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