On 2015 June 16, Fermi-LAT observed a giant outburst from the flat spectrum radio quasar 3C 279 with a peak $>100$ MeV flux of $\sim3.6\times10^{-5}\;{\rm photons}\;{\rm cm}^{-2}\;{\rm s}^{-1}$ ...averaged over orbital period intervals. It is the historically highest $\gamma$-ray flux observed from the source including past EGRET observations, with the $\gamma$-ray isotropic luminosity reaching $\sim10^{49}\;{\rm erg}\;{\rm s}^{-1}$. During the outburst, the Fermi spacecraft, which has an orbital period of 95.4 min, was operated in a special pointing mode to optimize the exposure for 3C 279. For the first time, significant flux variability at sub-orbital timescales was found in blazar observations by Fermi-LAT. The source flux variability was resolved down to 2-min binned timescales, with flux doubling times less than 5 min. The observed minute-scale variability suggests a very compact emission region at hundreds of Schwarzschild radii from the central engine in conical jet models. A minimum bulk jet Lorentz factor ($\Gamma$) of 35 is necessary to avoid both internal $\gamma$-ray absorption and super-Eddington jet power. In the standard external-radiation-Comptonization scenario, $\Gamma$ should be at least 50 to avoid overproducing the synchrotron-self-Compton component. However, this predicts extremely low magnetization ($\sim5\times10^{-4}$). Equipartition requires $\Gamma$ as high as 120, unless the emitting region is a small fraction of the dissipation region. Alternatively, we consider $\gamma$ rays originating as synchrotron radiation of $\gamma_{\rm e}\sim1.6\times10^6$ electrons, in magnetic field $B\sim1.3$ kG, accelerated by strong electric fields $E\sim B$ in the process of magnetoluminescence. At such short distance scales, one cannot immediately exclude production of $\gamma$ rays in hadronic processes.
Dark matter in the Milky Way may annihilate directly into gamma rays, producing a monoenergetic spectral line. Therefore, detecting such a signature would be strong evidence for dark matter ...annihilation or decay. We search for spectral lines in the Fermi Large Area Telescope observations of the Milky Way halo in the energy range 200 MeV-500 GeV using analysis methods from our most recent line searches. The main improvements relative to previous works are our use of 5.8 years of data reprocessed with the Pass 8 event-level analysis and the additional data resulting from the modified observing strategy designed to increase exposure of the Galactic center region. We search in five sky regions selected to optimize sensitivity to different theoretically motivated dark matter scenarios and find no significant detections. In addition to presenting the results from our search for lines, we also investigate the previously reported tentative detection of a line at 133 GeV using the new Pass 8 data.
The development of parenteral solution dosage forms of interferon alpha 2 (rhIFN-alpha2) without human albumin may significantly diminish the problem of forming highly immunogenic rhIFN-alpha 2b ...aggregates and the potential risk of blood-transmitted diseases caused by infectious viruses and often living pathogens that may be present in the plasma. With this purpose, we evaluated the compatibility of type I borosilicate glass vials and chlorobutyl stoppers with rhIFN-alpha 2b in an aqueous solution. At the same time, we carried out a targeted formulation screen at 37 degrees C of single or combined (e.g. polysorbate 80, EDTA Na(2), PEG 400) potentially stabilizing excipients. Quantified biochemical results from 12 independent batches of rhIFN-alpha 2b in a polysorbate/benzyl alcohol-based vehicle formulated at pH 7.4 were all found within the limits established by the World Health Organization for this cytokine. Real-time storage data confirmed the excellent biochemical long-term (30 months) stability of rhIFN-alpha 2b in this aqueous solution formulation. Analyses were performed at intervals throughout the time period using reverse-phase high-performance liquid chromatography, a sandwich-type enzyme-linked immunosorbent assay, and antiviral activity as stability-indicating assays. Furthermore, both the physical stability (color, odor, appearance, pH, and absence of particulate material) and the sterility of this formulation were maintained under the proposed shelf conditions.
The discovery of the gamma-ray pulsar PSR J1836+5925, powering the formerly unidentified EGRET source 3EG J1835+5918, was one of the early accomplishments of the Fermi Large Area Telescope (LAT). ...Sitting 25 degrees off the Galactic plane, PSR J1836+5925 is a 173 ms pulsar with a characteristic age of 1.8 million years, a spindown luminosity of 1.1$\times10^{34}$ erg s$^{-1}$, and a large off-peak emission component, making it quite unusual among the known gamma-ray pulsar population. We present an analysis of one year of LAT data, including an updated timing solution, detailed spectral results and a long-term light curve showing no indication of variability. No evidence for a surrounding pulsar wind nebula is seen and the spectral characteristics of the off-peak emission indicate it is likely magnetospheric. Analysis of recent XMM observations of the X-ray counterpart yields a detailed characterization of its spectrum, which, like Geminga, is consistent with that of a neutron star showing evidence for both magnetospheric and thermal emission.
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