16864996
A New Scenario on X-ray Shallow Decay of Gamma-ray Bursts
In this Letter, we propose that a microphysical process takes a vital role in the shocked region in which the prompt emission of GRBs is emitted. The turbulent energy is included in the internal energy transferred by the kinetic energy of the shock. It dissipates through stochastic acceleration for the electrons to supply the early X-ray emission in the phase of shallow decay. We put the constraints on the time evolution of microphysical parameters. The early X-ray fluxes can be obtained by this scenario and these results are consistent with the Swift observation
118151192
Emissive mechanism of radio flat spectrum on X-ray binaries
We present that the radio emission with flat spectrum in X-ray binaries comes from the synchrotron emission of relativistic electrons in the high energy tail of hot electrons in continuous conical jet. The jet is assumed to be produced by the advection-dominated accretion flow (ADAF) and maintains ion and electron temperatures constant in the case of adiabatic steady conical expansion. The flat spectrum is result of self-absorbed synchrotron emission by relativistic thermal electrons. We find that the critical frequency at which the radiation becomes optically thin declines along the jet. The emission observed at higher frequencies originates at smaller distance, closer to the base of the jet. The highest cut-off frequency of the flat spectrum is at the base of the jet, and is determined by the physics of the ADAF and the position of the jet formation. We assert that it is a characteristic of the ADAF in black hole X-ray binaries that a continuous steady outflow is formed and causes the observed flat spectrum in the low/hard state. The observed synchrotron emission consists of the flat spectral component from the jet and the steep spectral component from the ADAF. The flat spectral component extends from infrared to radio wavelengths, while the steep spectral component with the 2/5 spectral slope extends from infrared to shorter wavelengths, it will be dominated by the thermal emission from companion star.
17685255
Knot in centaurus A: A stochastic magnetic field for diffusive synchrotron radiation?
The emission of relativistic electrons moving in the random and small-scale magnetic field is presented by diffusive synchrotron radiation (DSR). In this Letter, we revisit the perturbative treatment of DSR. We propose that a random and small-scale magnetic field might be generated by the turbulence. As an example, multiband radiation of the knot in Cen A comes from the electrons with energy gamma(e) similar to 10(3 -) 10(4) in the magnetic field of 10(-3) G. The multiband spectrum of DSR is well determined by the feature of a stochastic magnetic field. These results put strong constraints on the models of particle acceleration.
17321754
Implications of Bulk Velocity Structures in AGN Jets
Synchrotron self-Compton (SSC) models and External Compton (EC) models of AGN jets with continually longitudinal and transverse bulk velocity structures have been constructed. The observed spectra show complex and interesting patterns in different velocity structures and viewing angles. These models were used to calculate the synchrotron and inverse Compton spectra of two typical BL Lac objects (BLO) (Mrk 421 and 0716+714) and (one) Flat Spectrum Radio Quasars (FSRQs) (3C 279), and to discuss the implications of jet bulk velocity structures in a unification of the BLO and FR I radio galaxies (FRI). By calculating the synchrotron spectra and SSC spectra of BL Lac object jets with continually bulk velocity structures, we have found that the spectra are much different from those in jets with a uniform velocity structure under increasing viewing angles. The unification of BLO and FRI is less constrained by the viewing angles, and would be imprinted by velocity structures intrinsic to the jets, themselves. By considering jets with bulk velocity structures constrained by the apparent speed, we discuss the velocity structures imprinted on the observed spectra for different viewing angles. We find that the spectra are greatly impacted by longitudinal velocity structures, because the volume elements are compressed or expanded. Finally, we present the EC spectra of FSRQs and FR II radio galaxies (FRII), and find that they are weakly affected by the velocity structures compared to synchrotron and SSC spectra.
119294737
The new model of fitting the spectral energy distributions of Mrk 421 and Mrk 501
The spectral energy distribution (SED) of TeV blazars has a double-humped shape that is usually interpreted as a Synchrotron Self Compton (SSC) model. The one zone SSC model is used broadly but cannot fit the high energy tail of SED very well. It needs a bulk Lorentz factor which is in conflict with the observation. Furthermore, a one zone SSC model cannot explain the entire spectrum. We propose a new model where the high energy emission is produced by the accelerated protons in the blob with a small size and high magnetic field, and the low energy radiation comes from the electrons in the expanded blob. Because the high and low energy photons are not produced at the same time, the requirement of a large Doppler factor from pair production is relaxed. We present the fitting results of the SEDs for Mrk 501 during April 1997 and Mrk 421 during March 2001.
118510926
A NEW RESULT ON THE ORIGIN OF THE EXTRAGALACTIC GAMMA-RAY BACKGROUND
In this paper, we repeatedly use the method of image stacking to study the origin of the extragalactic gamma-ray background (EGB) at GeV bands, and find that the Faint Images of the Radio Sky at Twenty centimeters (FIRST) sources undetected by the Large Area Telescope on the Fermi Gamma-ray Space Telescope can contribute about (56 +/- 6)% of the EGB. Because FIRST is a flux-limited sample of radio sources with incompleteness at the faint limit, we consider that point sources, including blazars, non-blazar active galactic nuclei, and starburst galaxies, could produce a much larger fraction of the EGB.
54682320
INTEGRAL and Swift/XRT observations of the source PKS 0208-512
Aims. The active galaxy PKS 0208-512, detected at lower energies by COMPTEL, has been claimed to be a MeV blazar from EGRET. We report on the most recent INTEGRAL observations of the blazar PKS 0208-512, which are supplemented by Swift ToO observations. Methods. The high energy X-ray and gamma-ray emission of PKS 0208-512 during August-December 2008 has been studied using 682 ks of INTEGRAL guest observer time and similar to 56 ks of Swift/XRT observations. These data were collected during the decay of a gamma-ray flare observed by Fermi/LAT. Results. At X-ray energies (0.2-10 keV) PKS 0208-512 is significantly detected by Swift/XRT, showing a power-law spectrum with a photon index of similar to 1.64. Its X-ray luminosity varied by roughly 30% during one month. At hard X-/soft gamma-ray energies PKS 0208-512 shows a marginally significant (similar to 3.2 sigma) emission in the 0.5-1 MeV band when combining all INTEGRAL/SPI data. Non-detections at energies below and above this band by INTEGRAL/SPI may indicate intrinsic excess emission. If this possible excess is produced by the blazar, one possible explanation could be that its jet consists of an abundant electron-positron plasma, which may lead to the emission of an annihilation radiation feature. Assuming this scenario, we estimate physical parameters of the jet of PKS 0208-512.
119235628
INTEGRAL AND SWIFT OBSERVATIONS OF THE Be X-RAY BINARY 4U 1036-56 (RX J1037.5-5647) AND ITS POSSIBLE RELATION WITH gamma-RAY TRANSIENTS
We present timing, spectral, and long-term temporal analysis of the high-mass X-ray binary 4U 1036-56 using INTEGRAL and Swift observations. We show that it is a weak hard X-ray source spending a major fraction of the time in quiescence and only occasionally characterized by X-ray outbursts. The outburst activity we report here lasts several days, with a dynamic range spanned by the luminosity in quiescence and in outburst as high as similar to 30. We report the detection of pulse period at 854.75 +/- 4.39 s during an outburst, which is consistent with previous measurements. Finally, we analyze the possibility of the association of 4U 1036-56 with the unidentified transient gamma-ray sources AGL J1037-5708 and GRO J1036-55, as prompted by its positional correlation.
150367978
AUTOMATED MICROWAVE LOW POWER TESTING TECHNIQUES FOR
As part of the Next Linear Collider (NLC) collaboration, the NLC structures group at Fermilab has started an R&D program to fabricate NLC accelerator structures in cooperation with commercial companies in order to prepare for mass production of RF structures. To build the Next Linear Collider, thousands accelerator structures containing a million cells are needed. Our primary goal is to explore the feasibility of making these structures in an industrial environment. On the other hand the structure mass production requires industrialized microwave quality control techniques to characterize these structures at different stages of production as efficiently as possible. We developed several automated set-ups based on different RF techniques that are mutually complementary address this problem.
119972193
Measurements of total reaction cross sections for some light nuclei at intermediate energies
Measurements of the total reaction cross section for C12-16, N14-17, and O16-18 on carbon target at intermediate energies were performed on the Radioactive Ion Beam Line of the Heavy ion Research Facility in Lanzhou. A larger enhancement of sigma(R) for C-15 was observed than for its neighbors. Evidence for possible anomalous nuclear structure in C-15 was revealed in the analysis of the total reaction cross section in terms of the difference factor d.
118454726
Search for light resonances decaying into pairs of muons as a signal of new physics
A search for groups of collimated muons is performed using a data sample collected by the CMS experiment at the LHC, at a centre-of-mass energy of 7TeV, and corresponding to an integrated luminosity of 35 pb−1. The analysis searches for production of new low-mass states decaying into pairs of muons and is designed to achieve high sensitivity to a broad range of models predicting leptonic jet signatures. With no excess observed over the background expectation, upper limits on the production cross section times branching fraction times acceptance areset, ranging from 0.1 to 0.5 pb at the 95% CL depending on event topology. In addition, the results are interpreted in several benchmark models in the context of supersymmetry with a new light dark sector exploring previously inaccessible parameter space.