Study of 23 day periodicity of Blazar Mkn501 in 1997

We confirm a 23 day periodicity during a large flare in 1997 for X-ray data of X-ray satellite RXTE all sky monitor(ASM), 2 TeV gamma ray data from Utah Seven Telescope and HEGRA, with a Fourier analysis. We found the three results to be the same with a newly estimated error. We confirm the presence of a frequency dependent power (1/f noise) in a frequency-power diagram. Further, we calculated a chance probability of the occurrence of the 23 day periodicity by considering the 1/f noise and obtained a chance probability 4.88*10^-3 for the HEGRA data: this is more significant than previous result by an order. We also obtained an identical peridoicity with another kind of timing analysis-epoch folding method for the ASM data and HEGRA data. We strongly suggest an existence of the periodicity. We divided the HEGRA data into two data sets, analyzed them with a Fourier method, and found an unstableness of the periodicity with a 3.4 sigma significance. We also analyzed an energy spectra of the X-ray data of a RXTE proportional counter array and we found that a combination of three parameters-a magnetic field, a Lorentz factor, and a beaming factor-is related to the periodicity.Comment: 25 page, 27 figures, acceptted by astroparticle physic

X-ray thermal emission from the jet of M87 with Chandra

With new calibration data, thermal emission from the jet of radio galaxy M87 is studied with about 700 ks archival data with Chandra. For nucleus, HST-1, knot D, X-ray energy spectra is well fitted with a power law. However, For knot A, a power law model is rejected with a high significance and an X-ray energy spectra is well fitted with a combination model of a power law and an apec model of 0.2 keV and a metal abundance 0.00. Thermal emission from knot A is confirmed.Comment: 20 pages, 10 tables, 2 figure

Thermal Design of Power Semiconductor Modules for Mobile Communication Systems

We will describe the thermal performance of power semiconductor module, which consists of hetero-junction bipolar transistors (HBTs), for mobile communication systems. We calculate the thermal resistance between the HBT fingers and the bottom surface of a multi-layer printed circuit board (PCB) using a finite element method (FEM). We applied a steady state analysis to evaluate the influence of design parameters on thermal resistance of the module. We found that the thickness of GaAs substrate, the thickness of multi-layer circuit board, the thermal conductivity of bonding material under GaAs substrate, and misalignment of thermal vias between each layer of PCB are the dominant parameter in thermal resistance of the module.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions