Corehead Orchard Tree Establishment and Grazing Damage Survey 2013: Report to the Borders Forest Trust

The research report describes the history of fruit orchards in Scotland and monitoring of efforts to establish a traditional fruit orchard. Comparisons are made of the performance of different fruit varieties during the first two years of growth and the effects of deer browsing are discussed

The reprocessing features in the X-ray spectrum of the NELG MCG-5-23-16

We present results from the spectral analysis of the Seyfert 1.9 galaxy MCG-5-23-16, based on ASCA, BeppoSAX, Chandra and XMM-Newton observations. The spectrum of this object shows a complex iron Kalpha emission line, which is best modeled by a superposition of a narrow and a broad (possibly relativistic) iron line, together with a Compton reflection component. Comparing results from all (six) available observations, we do not find any significant variation in the flux of both line components. The moderate flux continuum variability (about 25% difference between the brightest and faintest states), however, does not permit us to infer much about the location of the line-emitting material. The amount of Compton reflection is lower than expected from the total iron line EW, implying either an iron overabundance or that one of the two line components (most likely the narrow one) originates in Compton-thin matter.Comment: Accepted for publication in A&

A Chandra view of the clumpy reflector at the heart of the Circinus galaxy

We present a spectral and imaging analysis of the X-ray reflecting structure at the heart of the Circinus galaxy, investigating the innermost regions surrounding the central black hole. By studying an archival 200 ks Chandra ACIS-S observation, we are able to image the extended clumpy structure responsible for both cold reflection of the primary radiation and neutral iron Ka line emission. We measure an excess of the equivalent width of the iron Ka line which follows an axisymmetric geometry around the nucleus on a hundred pc scale. Spectra extracted from different regions confirm a scenario in which the dominant mechanism is the reflection of the nuclear radiation from Compton-thick gas. Significant differences in the equivalent width of the iron Ka emission line (up to a factor of 2) are found. It is argued that these differences are due to different scattering angles with respect to the line of sight rather than to different iron abundances.Comment: 6 pages, 4 figures, accepted for publication on MNRA

Generalized universal instability: Transient linear amplification and subcritical turbulence

In this work we numerically demonstrate both significant transient (i.e. non-modal) linear amplification and sustained nonlinear turbulence in a kinetic plasma system with no unstable eigenmodes. The particular system considered is an electrostatic plasma slab with magnetic shear, kinetic electrons and ions, weak collisions, and a density gradient, but with no temperature gradient. In contrast to hydrodynamic examples of non-modal growth and subcritical turbulence, here there is no sheared flow in the equilibrium. Significant transient linear amplification is found when the magnetic shear and collisionality are weak. It is also demonstrated that nonlinear turbulence can be sustained if initialized at sufficient amplitude. We prove these two phenomena are related: when sustained turbulence occurs without unstable eigenmodes, states that are typical of the turbulence must yield transient linear amplification of the gyrokinetic free energy

A Chandra Observation of M51: Active Nucleus and Nuclear Outflows

We present a Chandra ACIS-S observation of the nuclear region of the nearby spiral galaxy M51 (NGC 5194), which has a low-luminosity Seyfert 2 nucleus. The X-ray image shows the nucleus, southern extranuclear cloud, and northern loop, the morphology of the extended emission being very similar to those seen in radio continuum and optical emission line images. The X-ray spectrum of the nucleus is well represented by a model consisting of soft thermal plasma with kT ~0.5 keV, a very hard continuum, and an Fe Kalpha emission line at 6.45 keV with an equivalent width of >2 keV. The very strong Fe line and the flat continuum indicate that the nucleus is obscured by a column density in excess of 10^24 cm^-2 and the spectrum is dominated by reflected emission from cold matter near the nucleus. The X-ray spectra of the extranuclear clouds are well fitted by a thermal plasma model with kT ~0.5 keV. This spectral shape and morphology strongly suggest that the clouds are shock heated by the bi-polar outflow from the nucleus. The shock velocities of the extranuclear cloud and northern loop inferred from the temperatures of the X-ray gas are 690 km/s and 660 km/s, respectively. By assuming a steady-state situation in which the emission of the extranuclear clouds is powered by the jets, the mechanical energy in the jets is found to be comparable to the bolometric luminosity of the nucleus.Comment: 7 pages, 5 figures, Accepted for publication in the Astrophyscal Jouna