[en] During a search for gamma-ray emission from NGC 3628 (Arp 317), two new unidentified gamma-ray sources were discovered, Fermi J1049.7+0435 and J1103.2+1145. The detections were made using data from the Large Area Telescope (LAT), on board the Fermi Gamma-Ray Space Telescope, in the 100 MeV to 300 GeV band during the period between 2008 August 5 and 2012 October 27. Neither detection is coincident with any source listed in the second Fermi-LAT (2FGL) catalog. Fermi J1049.7+0435 is at Galactic coordinates (l, b) = (245.°34, 53.°27), (α_J2000, δ_J2000) = (162.°43, 4.°60). Fermi J1103.2+1145 is at Galactic coordinates (l, b) = (238.°85, 60.°33), (α_J2000, δ_J2000) = (165.°81, 11.°75). Possible radio counterparts are found for both sources, which show flat radio spectra similar to other Fermi-LAT detected active galactic nuclei, and their identifications are discussed.

[en] Compact radio sources sometimes exhibit intervals of large, rapid changes in their flux density, due to lensing by interstellar plasma crossing the line of sight. A novel survey program has made it possible to discover these “Extreme Scattering Events” (ESEs) in real time, resulting in a high-quality dynamic spectrum of an ESE observed in PKS 1939–315. Here we present a method for determining the column-density profile of a plasma lens, given only the dynamic radio spectrum of the lensed source, under the assumption that the lens is either axisymmetric or totally anisotropic. Our technique relies on the known, strong frequency dependence of the plasma refractive index in order to determine how points in the dynamic spectrum map to positions on the lens. We apply our method to high-frequency (4.2–10.8 GHz) data from the Australia Telescope Compact Array of the PKS 1939–315 ESE. The derived electron column-density profiles are very similar for the two geometries we consider, and both yield a good visual match to the data. However, the fit residuals are substantially above the noise level, and deficiencies are evident when we compare the predictions of our model to lower-frequency (1.6–3.1 GHz) data on the same ESE, thus motivating future development of more sophisticated inversion techniques

[en] We use data on extreme radio scintillation to demonstrate that this phenomenon is associated with hot stars in the solar neighborhood. The ionized gas responsible for the scattering is found at distances up to $1.75\mathrm{p}\mathrm{c}$ from the host star, and on average must comprise ∼10⁵ distinct structures per star. We detect azimuthal velocities of the plasma, relative to the host star, up to $9.7\mathrm{k}\mathrm{m}{\mathrm{s}}^{-<!--\; ???\; -->1}$, consistent with warm gas expanding at the sound speed. The circumstellar plasma structures that we infer are similar in several respects to the cometary knots seen in the Helix and in other planetary nebulae. There the ionized gas appears as a skin around tiny molecular clumps. Our analysis suggests that molecular clumps are ubiquitous circumstellar features, unrelated to the evolutionary state of the star. The total mass in such clumps is comparable to the stellar mass.

[en] The River Hayle in south-west England is impacted with metals and can be divided into three regions depending on the copper and zinc concentrations: a low-metal upper section; a highly-contaminated middle section and a moderately contaminated lower section. Hayle river water is toxic to metal-naive brown trout, but brown trout are found in the upper and lower regions. The study aimed to evaluate the population genetic structure of River Hayle brown trout and to determine if the highly-contaminated section acts as a chemical barrier to migration. Population genetic analysis indicated that metals were not a barrier to gene flow within the river, but there was a high level of differentiation observed between fish sampled at two sites in the upper region, despite being separated by only 1 km. The metal tolerance trait exhibited by this brown trout population may represent an important component of the species genetic diversity in this region. - Highlights: → River Hayle, Cornwall, UK, water is toxic to metal-naive brown trout. → Some brown trout populations resident in the River Hayle are tolerant of elevated metals (e.g. copper and zinc). → Elevated metals do not affect the gene flow between sites on the river. → The population genetic structure of the brown trout in the River Hayle appears unaffected by elevated metals. - Aquatic metal pollution does not affect the gene flow between brown trout resident below and above a metal mining waste discharge point in the River Hayle, Cornwall, UK.

[en] We present multiwavelength observations of the persistent Fermi-Large Area Telescope unidentified γ-ray source 1FGL J1417.7–4407, showing it is likely to be associated with a newly discovered X-ray binary containing a massive neutron star (nearly $2M_{\odot <!--\; ???\; -->}$) and a $\sim <!--\; ???\; -->0.35M_{\odot <!--\; ???\; -->}$ giant secondary with a 5.4 day period. SOAR optical spectroscopy at a range of orbital phases reveals variable double-peaked Hα emission, consistent with the presence of an accretion disk. The lack of radio emission and evidence for a disk suggests the γ-ray emission is unlikely to originate in a pulsar magnetosphere, but could instead be associated with a pulsar wind, relativistic jet, or could be due to synchrotron self-Compton at the disk–magnetosphere boundary. Assuming a wind or jet, the high ratio of γ-ray to X-ray luminosity (∼20) suggests efficient production of γ-rays, perhaps due to the giant companion. The system appears to be a low-mass X-ray binary that has not yet completed the pulsar recycling process. This system is a good candidate to monitor for a future transition between accretion-powered and rotational-powered states, but in the context of a giant secondary.

[en] Quasi-simultaneous observations of the Flat Spectrum Radio Quasar PKS 2326−502 were carried out in the γ -ray, X-ray, UV, optical, near-infrared, and radio bands. Using these observations, we are able to characterize the spectral energy distribution (SED) of the source during two flaring and one quiescent γ -ray states. These data were used to constrain one-zone leptonic models of the SEDs of each flare and investigate the physical conditions giving rise to them. While modeling one flare required only changes in the electron spectrum compared to the quiescent state, modeling the other flare required changes in both the electron spectrum and the size of the emitting region. These results are consistent with an emerging pattern of two broad classes of flaring states seen in blazars. Type 1 flares are explained by changes solely in the electron distribution, whereas type 2 flares require a change in an additional parameter. This suggests that different flares, even in the same source, may result from different physical conditions or different regions in the jet.

[en] PKS 2142–75 (a.k.a. 2FGL J2147.4–7534) is a flat-spectrum radio quasar that was observed quasi-simultaneously by a suite of instruments across the electromagnetic spectrum during two flaring states in 2010 April and 2011 August as well as a quiescent state from 2011 December through 2012 January. The results of these campaigns and model spectral energy distributions (SEDs) from the active and quiescent states are presented. The SED model parameters of PKS 2142–75 indicate that the two flares of the source are created by unique physical conditions. SED studies of flat-spectrum radio quasars are beginning to indicate that there might be two types of flares, those that can be described purely by changes in the electron distribution and those that require changes in other parameters, such as the magnetic field strength or the size of the emitting region.