Angular, spectral, and time distributions of highest energy protons and associated secondary gamma-rays and neutrinos propagating through extragalactic magnetic and radiation fields

The angular, spectral and temporal features of the highest energy protons and accompanying them secondary neutrinos and synchrotron gamma-rays propagating through the intergalactic magnetic and radiation fields are studied using the analytical solutions of the Boltzmann transport equation obtained in the limit of the small-angle and continuous-energy-loss approximation.Comment: 21 pages, 13 figure

Electron Acceleration and Time Variability of High Energy Emission from Blazars

Blazars are known to emit a broad band emission from radio to gamma-rays with rapid time variations, particularly, in X- and gamma-rays. Synchrotron radiation and inverse Compton scattering are thought to play an important role in emission and the time variations are likely related to the acceleration of nonthermal electrons. As simultaneous multiwavelength observations with continuous time spans are recently available, some characteristics of electron acceleration are possibly inferred from the spectral changes of high energy emission. In order to make such inferences, we solve the time-dependent kinetic equations of electrons and photons simultaneously using a simple model for electron acceleration. We then show how the time variations of emission are dependent on electron acceleration. We also present a simple model for a flare in X-rays and TeV gamma-rays by temporarily changing the acceleration timescale. Our model will be used, in future, to analyze observed data in detail to obtain information on electron acceleration in blazars.Comment: 24 pages, 12 figures, accepted by the Astrophysical Journa

Energetics of Tev Blazars and Physical Constraints on their Emission Regions

Using multi-frequency spectra from TeV blazars in quiescent states, we obtain the physical parameters of the emission region of blazars within the framework of the one-zone synchrotron self-Compton (SSC) model. We numerically calculate the steady-state energy spectra of electrons by self-consistently taking into account the effects of radiative cooling with a proper account of the Klein-Nishina effects. Here electrons are assumed to be injected with a power-law spectrum and to escape on a finite time scale, which naturally leads to the existence of a break energy scale. Although we do not use time variabilities but utilize a model of electron escape to constrain the size of the emission region, the resultant size turns out to be similar to that obtained based on time variabilities. Through detailed comparison of the predicted emission spectra with observations, we find that for Mrk 421, Mrk 501, and PKS 2155--304, the energy density of relativistic electrons is about an order of magnitude larger than that of magnetic fields with an uncertainty within a factor of a few.Comment: Accepted for publication in Ap

Temporal and Spectral Variabilities of High Energy Emission from Blazars Using Synchrotron Self-Compton Models

Multiwavelength observations of blazars such as Mrk 421 and Mrk 501 show that they exhibit strong short time variabilities in flare-like phenomena. Based on the homogeneous synchrotron self-Compton (SSC) model and assuming that time variability of the emission is initiated by changes in the injection of nonthermal electrons, we perform detailed temporal and spectral studies of a purely cooling plasma system. One important parameter is the total injected energy E and we show how the synchrotron and Compton components respond as E varies. We discuss in detail how one could infer important physical parameters using the observed spectra. In particular, we could infer the size of the emission region by looking for exponential decay in the light curves. We could also test the basic assumption of SSC by measuring the difference in the rate of peak energy changes of synchrotron and SSC peaks. We also show that the trajectory in the photon-index and flux plane evolves clockwise or counter-clockwise depending on the value of E and observed energy bands.Comment: 35 pages, 18 figures, accepted by the Astrophysical Journa

The Electron Spectrum in 3C279 and the Observed Emission Spectrum

The emission mechanisms of the blazar 3C 279 are studied by solving the kinetic equations of electrons and photons in a relativistically moving blob. The gamma-ray spectral energy distribution (SED) is fitted by inverse Compton scattering of external photons. The bulk Lorentz factor of the emitting blob is found to be 25, and the magnetic field is found to be 0.3 G. GeV gamma-rays are well explained by inefficiently cooled electrons because of the Klein-Nishina effects. The electron spectrum is not a broken power law with a steeper spectrum above a break energy, which is often used to fit the observed SED. The kinetic energy density of the nonthermal electrons dominates the magnetic energy density; this result is qualitatively the same as that for TeV blazars such as Mrk 421 and Mrk 501. The gamma-ray luminosity of 3C 279 is often observed to increase rapidly. We show that one of the better sampled gamma-ray flares can be explain by the internal shock model.Comment: 9 pages, 3 figures, to be published in the Astrophysical Journal, Letter

Subaru optical observations of the old pulsar PSR B0950+08

We report the B band optical observations of an old (17.5 Myr) radiopulsar PSR B0950+08 obtained with the Suprime-Cam at the Subaru telescope. We detected a faint object, B=27.07(16). Within our astrometrical accuracy it coincides with the radio position of the pulsar and with the object detected earlier by Pavlov et al. (1996) in UV with the HST/FOC/F130LP. The positional coincidence and spectral properties of the object suggest that it is the optical counterpart of PSR B0950+08. Its flux in the B band is two times higher than one would expect from the suggested earlier Rayleigh-Jeans interpretation of the only available HST observations in the adjacent F130LP band. Based on the B and F130LP photometry of the suggested counterpart and on the available X-ray data we argue in favour of nonthermal origin of the broad-band optical spectrum of PSR B0950+08, as it is observed for the optical emission of the younger, middle-aged pulsars PSR B0656+14 and Geminga. At the same time, the optical efficiency of PSR B0950+08, estimated from its spin-down power and the detected optical flux, is by several orders of magnitude higher than for these pulsars, and comparable with that for the much younger and more energetic Crab pulsar. We cannot exclude the presence of a compact, about 1'', faint pulsar nebula around PSR B0950+08, elongated perpendicular to the vector of its proper motion, unless it is not a projection of a faint extended object on the pulsar position.Comment: 8 pages, LaTeX, aa.cls style, 5 PS figures, submitted to A&A. Image is available in FITS format at http://www.ioffe.rssi.ru/astro/NSG/obs/0950-subar

Combined carriership of TLR9-1237C and CD14-260T alleles enhances the risk of developing chronic relapsing pouchitis

AIM: To investigate the single nucleotide polymorphisms (SNPs) in genes involved in bacterial recognition and the susceptibility to pouchitis or pouchitis severity. METHODS: Analyses of CD14 -260C>T, CARD15/NOD2 3020insC, Toll-like receptor (TLR)4 +896A>G, TLR9 -1237T>C, TLR9+2848G>A, and IRAKM + 22148G>A SNPs were performed in 157 ileal-pouch anal anastomosis (IPAA) patients (79 patients who did not develop pouchitis, 43 infrequent pouchitis patients, 35 chronic relapsing pouchitis patients) and 224 Italian Caucasian healthy controls. RESULTS: No significant differences were found in SNP frequencies between controls and IPAA patients. However, a significant difference in carriership frequency of the TLR9-1237C allele was found between the infrequent pouchitis and chronic relapsing pouchitis groups [P = 0.028, oddos ratio (OR) = 3.2, 95%CI = 1.2-8.6]. This allele uniquely represented a 4-locus TLR9 haplotype comprising both studied TLR9 SNPs in Caucasians. Carrier trait analysis revealed an enhanced combined carriership of the alleles TLR9 -1237C and CD14 -260T in the chronic relapsing pouchitis and infrequent pouchitis group (P = 0.018, OR = 4.1, 95%CI = 1.4 -12.3). CONCLUSION: There is no evidence that the SNPs predispose to the need for IPAA surgery. The significant increase of the combined carriership of the CD14 -260T and TLR9 -1237C alleles in the chronic relapsing pouchitis group suggests that these markers identify a subgroup of IPAA patients with a risk of developing chronic or refractory pouchitis

Seawater redox variations during the deposition of the Kimmeridge Clay Formation, United Kingdom (Upper Jurassic): evidence from molybdenum isotopes and trace metal ratios

The Kimmeridge Clay Formation (KCF) and its equivalents worldwide represent one of the most prolonged periods of organic carbon accumulation of the Mesozoic. In this study, we use the molybdenum (Mo) stable isotope system in conjunction with a range of trace metal paleoredox proxies to assess how seawater redox varied both locally and globally during the deposition of the KCF. Facies with lower organic carbon contents (TOC 1–7 wt %) were deposited under mildly reducing (suboxic) conditions, while organic-rich facies (TOC >7 wt %) accumulated under more strongly reducing (anoxic or euxinic) local conditions. Trace metal abundances are closely linked to TOC content, suggesting that the intensity of reducing conditions varied repeatedly during the deposition of the KCF and may have been related to orbitally controlled climate changes. Long-term variations in ?98/95Mo are associated with the formation of organic-rich intervals and are related to third-order fluctuations in relative sea level. Differences in the mean ?98/95Mo composition of the organic-rich intervals suggest that the global distribution of reducing conditions was more extensive during the deposition of the Pectinatites wheatleyensis and lower Pectinatites hudlestoni zones than during the deposition of the upper Pectinatites hudlestoni and Pectinatites pectinatus zones. The global extent of reducing conditions during the Kimmerigidan was greater than today but was less widespread than during the Toarcian (Early Jurassic) oceanic anoxic event. This study also demonstrates that the Mo isotope system in Jurassic seawater responded to changes in redox conditions in a manner consistent with its behavior in present-day sedimentary environment

Collective processes in relativistic plasma and their implications for gamma-ray burst afterglows

We consider the effects of collective plasma processes on synchrotron emission from highly relativistic electrons. We find, in agreement with Sazonov (1970), that strong effects are possible also in the absence of a non-relativistic plasma component, due to the relativistic electrons (and protons) themselves. In contrast with Sazonov, who infers strong effects only in cases where the ratio of plasma frequency to cyclotron frequency is much larger than the square of the characteristic electron Lorentz factor, nu_p/nu_B >> gamma^2, we find strong effects also for 1 << nu_p/nu_B << gamma^2. The modification of the spectrum is prominent at frequencies nu < nu_{R*} = nu_p min[gamma, (nu_p/nu_B)^(1/2)], where nu_{R*} generalizes the Razin-Tsytovich frequency, nu_R = gamma nu_p, to the regime nu_p/nu_B << gamma^2. Applying our results to gamma-ray burst (GRB) plasmas, we predict a strong modification of the radio spectrum on minute time scale following the GRB, at the onset of fireball interaction with its surrounding medium, in cases where the ratio of the energy carried by the relativistic electrons to the energy carried by the magnetic field exceeds ~ 10^5. Plausible electron distribution functions may lead to negative synchrotron reabsorption, i.e to coherent radio emission, which is characterized by a low degree of circular polarization. Detection of these effects would constrain the fraction of energy in the magnetic field, which is currently poorly determined by observations, and, moreover, would provide a novel handle on the properties of the environment into which the fireball expands.Comment: 28 pages, 1 figure, submitted to Ap

A Model of Polarized X-ray Emission from Twinkling Synchrotron Supernova Shells

Synchrotron X-ray emission components were recently detected in many young supernova remnants (SNRs). There is even an emerging class - SN1006, RXJ1713.72-3946, Vela Jr, and others - that is dominated by non-thermal emission in X-rays, also probably of synchrotron origin. Such emission results from electrons/positrons accelerated well above TeV energies in the spectral cut-off regime. In the case of diffusive shock acceleration, which is the most promising acceleration mechanism in SNRs, very strong magnetic fluctuations with amplitudes well above the mean magnetic field must be present. Starting from such a fluctuating field, we have simulated images of polarized X-ray emission of SNR shells and show that these are highly clumpy with high polarizations up to 50%. Another distinct characteristic of this emission is the strong intermittency, resulting from the fluctuating field amplifications. The details of this "twinkling" polarized X-ray emission of SNRs depend strongly on the magnetic-field fluctuation spectra, providing a potentially sensitive diagnostic tool. We demonstrate that the predicted characteristics can be studied with instruments that are currently being considered. These can give unique information on magnetic-field characteristics and high-energy particle acceleration in SNRs.Comment: 7 pages, 8 figures, MNRAS (in press