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.
118436895
Mechanism of very high energy radiation in BL Lacertae object 3C 66A
Aims. Our goal is to understand the nature of blazars and the mechanisms for generating high-energy.-rays, through investigation of the blazar 3C 66A. Methods. We model the high-energy spectrum of 3C 66A, which was observed recently with the Fermi-LAT and VERITAS telescopes. The spectrum has a hard change from the energy range of 0.2-100 GeV to 200-500 GeV in recent almost contemporaneous observations of two telescopes. Results. The de-absorbed VERITAS spectrum depends strongly on redshift, which is highly uncertain. If z = 0.444 is adopted, we are able to use the SSC model to produce the Fermi-LAT component and the EC model to the VERITAS component. However, if z = 0.1, the intrinsic VERITAS spectrum will be softer, and there will be a smooth link between the Fermi-LAT and VERITAS spectra that can be explained using an SSC model.
14071619
The Mass Distribution of Black Holes in BL Lacertae Objects
In this {\it Letter}, we make an attempt to estimate the masses of black holes and their distributions in BL Lac objects. We find there is a bimodal population of black hole masses in BL Lacs: the first has a lower-mass peak centred at $\sim 7.0 \times 10^6\sunm$ composed of high frequency-peaked BL Lacs (HBLs) and the second is a higher-mass ($>10^9\sunm$) population composed of low frequency-peaked BL Lacs (LBLs). The low mass family of black holes in HBLs does not satisfy the Magorrian et al. relation whereas the high mass family in LBLs does this relation and is in agreement with Laor's limit. The origination of the bimodal distribution of black hole mass remains open.
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.
118677286
Gamma-ray Burst Prompt Emission: Jitter Radiation in Stochastic Magnetic Field Revisited
We revisit the radiation mechanism of relativistic electrons in the stochastic magnetic field and apply it to the high-energy emissions of gamma-ray bursts (GRBs). We confirm that jitter radiation is a possible explanation for GRB prompt emission in the condition of a large electron deflection angle. In the turbulent scenario, the radiative spectral property of GRB prompt emission is decided by the kinetic energy spectrum of turbulence. The intensity of the random and small-scale magnetic field is determined by the viscous scale of the turbulent eddy. The microphysical parameters epsilon(e) and epsilon(B) can be obtained. The acceleration and cooling timescales are estimated as well. Due to particle acceleration in magnetized filamentary turbulence, the maximum energy released from the relativistic electrons can reach a value of about 10(14) eV. The GeV GRBs are possible sources of high-energy cosmic-ray.
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.
118274966
Search for electroweak production of charginos and neutralinos using leptonic final states in pp collisions at $ \sqrt{s}=7 $ TeV
A bstractThe 2011 dataset of the CMS experiment, consisting of an integrated luminosity of 4.98 fb−1 of pp collisions at $ \sqrt{s}=7 $ TeV, enables expanded searches for direct electroweak pair production of charginos and neutralinos in supersymmetric models as well as their analogs in other models of new physics. Searches sensitive to such processes, with decays to final states that contain two or more leptons, are presented. Final states with three leptons, with a same-sign lepton pair, and with an opposite-sign lepton pair in conjunction with two jets, are examined. No excesses above the standard model expectations are observed. The results are used in conjunction with previous results on four-lepton final states to exclude a range of chargino and neutralino masses from approximately 200 to 500 GeV in the context of models that assume large branching fractions of charginos and neutralinos to leptons and vector bosons.
119231982
A POSSIBLE ULTRA STRONG AND BROAD Fe Kα EMISSION LINE IN SEYFERT 2 GALAXY IRAS 00521-7054
We present XMM-Newton spectra of the Seyfert 2 Galaxy IRAS 00521-7054. A strong feature at {approx}6 keV (observer's frame) can be formally fitted with a strong (EW = 1.3 {+-} 0.3 keV in the rest frame) and broad Fe K{alpha} line, extending down to 3 keV. The underlying X-ray continuum could be fitted with an absorbed power law (with {Gamma} = 1.8 {+-} 0.2 and N{sub H} 5.9{sup +0.6}{sub -0.7} Multiplication-Sign 10{sup 22} cm{sup -2}) plus a soft component. If due to relativistically smeared reflection by an X-ray illuminated accretion disk, the spin of the supermassive black hole (SMBH) is constrained to be 0.97{sup +0.03}{sub -0.13} (errors at 90% confidence level for one interesting parameter), and the accretion system is viewed at an inclination angle of 37 Degree-Sign {+-} 4 Degree-Sign . This would be the first type 2 active galactic nucleus reported with strong red Fe K{alpha} wing detected which demands a fast rotating SMBH. The unusually large EW would suggest that the light bending effect is strong in this source. Alternatively, the spectra could be fitted by a dual-absorber model (though with a global {chi}{sup 2} higher by {approx}6 for 283 dof) with N{sub H1} 7.0 {+-} 0.8more » Multiplication-Sign 10{sup 22} cm{sup -2} covering 100% of the X-ray source, and N{sub H2} = 21.7{sup +5.6}{sub -5.4} Multiplication-Sign 10{sup 22} cm{sup -2} covering 71%, which does not require an extra broad Fe K{alpha} line.« less
60626146
ILC Reference Design Report: ILC Global Design Effort and World Wide Study
121992643
The Wigner Functions for a Spin-1/2 Relativistic Particle in the Presence of Magnetic Field
This paper provides a study of Wigner functions for a spin-1/2 relativistic particle in the presence of magnetic field. Since the Dirac equation is described as a matrix equation, it is necessary to describe the Wigner function as a matrix function in phase space. What’s more, this function is then proved to satisfy the Dirac equation with ⋆-product. Finally, by solving the ⋆-product Dirac equation, the energy levels as well as the Wigner functions for a spin-1/2 relativistic particle in the presence of magnetic field are obtained.
119215988
Magnetic tuning of the relativistic BCS-BEC crossover
The effect of an applied magnetic field in the crossover from Bose-Einstein condensate (BEC) to Bardeen-Cooper-Schrieffer (BCS) pairing regimes is investigated. We use a model of relativistic fermions and bosons inspired by those previously used in the context of cold fermionic atoms and in the magnetic-color-flavor-locking phase of color superconductivity. It turns out that as with cold atom systems, an applied magnetic field can also tune the BCS-BEC crossover in the relativistic case. We find that no matter what the initial state is at B=0, for large enough magnetic fields the system always settles into a pure BCS regime. In contrast to the atomic case, the magnetic field tuning of the crossover in the relativistic system is not connected to a Feshbach resonance, but to the relative numbers of Landau levels with either BEC or BCS type of dispersion relations that are occupied at each magnetic field strength.