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.
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.
119173624
ON THE EVOLUTION OF THE CORES OF RADIO SOURCES AND THEIR EXTENDED RADIO EMISSION
The work in this paper aims at determining the evolution and possible co-evolution of radio-loud active galactic nuclei (AGNs) and their cores via their radio luminosity functions (i.e., total and core RLFs, respectively). Using a large combined sample of 1063 radio-loud AGNs selected at low radio frequency, we investigate the RLF at 408 MHz of steep-spectrum radio sources. Our results support a luminosity-dependent evolution. Using core flux density data of the complete sample 3CRR, we investigate the core RLF at 5.0 GHz. Based on the combined sample with incomplete core flux data, we also estimate the core RLF using a modified factor of completeness. Both results are consistent and show that the comoving number density of radio cores displays a persistent decline with redshift, implying a negative density evolution. We find that the core RLF is obviously different from the total RLF at the 408 MHz band which is mainly contributed by extended lobes, implying that the cores and extended lobes could not be co-evolving at radio emission.
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
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.
118843154
Performance and operation of the CMS electromagnetic calorimeter
The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75 848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented.
8388140
Stochastic Acceleration in the Western Hot Spot of Pictor A
Chandra's high-resolution observations of radio galaxies require a revisit of the relevant electron acceleration processes. Although the diffusive shock particle acceleration model may explain spectra of spatially unresolved sources, it encounters difficulties in explaining the structure and spectral properties of recently discovered Chandra X-ray features in several low-power radio sources. We argue that these observations strongly suggest stochastic electron acceleration by magnetized turbulence, and show that the simplest stochastic particle acceleration model with energy-independent acceleration and escape timescales can overcome most of these difficulties. We use the bright core of the western hot spot of Pictor A as an example to demonstrate the model characteristics, which may be tested with high-energy observations.
125581437
Measurement of CP violation parameter sin** 2(phi(1)) with 152 million B anti-B pairs
52970299
NNLL momentum-space threshold resummation in direct top quark production at the LHC
A bstractWe update the theoretical precision of the total cross section for direct top quark production at the LHC by extending the threshold resummation to the next-to-next-to-leading logarithmic accuracy.
118979006
Collisions among Clouds inside Dusty Tori in Active Galactic Nuclei: Observational Consequences
A geometrically thick dusty torus in NGC 1068 has been unambiguously resolved by an infrared interferometry telescope. This implies that clouds composing the dusty torus are undergoing supersonic collisions with each other. We show that the collisions form strong nonrelativistic shocks, which accelerate populations of relativistic electrons. The torus reprocesses emission from the accretion disk into an infrared band. We show that the energy density of the infrared photons inside the torus is much higher than that of the magnetic field in the clouds, and the seed photons of inverse Compton scattering are mainly from the infrared. The maximum energy of the relativistic electrons can reach a Lorentz factor of 105. We calculate the spectrum of the synchrotron and inverse Compton scattering radiation from the electrons in the torus. The relativistic electrons in the torus radiate nonthermal emission from radio to γ-ray, which isotropically diffuses in the region of the torus. We find that the most prominent character is a peak at ~0.5-1 GeV. We apply this model to NGC 1068 and find that the observed radio emission from the core component S1 can be explained by the synchrotron emission from the relativistic electrons. We predict that there is γ-ray emission with a luminosity of 1040 ergs s-1 peaking at ~1 GeV from the torus, which could be detected by the Gamma-Ray Large-Array Space Telescope in the future. This will provide a new clue to understanding the physics in the torus. The nonthermal radiation from the dusty torus may explain the radio emission from Seyfert galaxies. The cosmological implications of the nonthermal emission to the γ-ray background radiation are also discussed.