59,661 research outputs found

    Broad-line and Multi-wave Band Emission from Blazars

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    We study the correlations of the flux of the broad-line emission (FBLRF_{BLR}) 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 FBLRF_{BLR} and FXF_{X} and between LBLRL_{BLR} and LXL_{X} in both states for 39 FSRQs and the slopes of the linear regression equations are almost equal to 1. There are weak correlations between FBLRF_{BLR} and FXF_{X} and between LBLRL_{BLR} and LXL_{X} 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 FBLRF_{BLR} and FXF_{X} and between LBLRL_{BLR} and LXL_{X} 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 η\eta, whereas FSRQs have high accretion efficiency η\eta. 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

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    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

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    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

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    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 αroαox\alpha_{ro}-\alpha_{ox} 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, νp\nu _p, of each source is estimated by fitting the data with a parabolic function. In the plot of αrxlogνp\alpha_{rx}-\log \nu_p we find that, in the four different regions divided by the αrx=0.75\alpha_{rx}=0.75 line and the logνp=14.7\log \nu_p=14.7 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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