HESS J1507-622: an unique unidentified source off the Galactic Plane

Galactic very high energy (VHE, > 100 GeV) gamma ray sources in the inner Galaxy H.E.S.S. survey tend to cluster within 1 degree in latitude around the Galactic plane. HESS J1507-622 instead is unique, since it is located at latitude of ~3.5 degrees. HESS J1507-622 is slightly extended over the PSF of the instrument and hence its Galactic origin is clear. The search for counterparts in other wavelength regimes (radio, infrared and X-rays) failed to show any plausible counterparts; and given its position off the Galactic plane and hence the absorption almost one order of magnitude lower, it is very surprising to not see any counterparts especially at X-rays wavelengths (by ROSAT, XMM Newton and Chandra). Its latitude implies that it is either rather close, within about 1 kpc, or is located well off the Galactic plane. And also the models reflect the uniqueness of this object: a leptonic PWN scenario would place this source due to its quite small extension to multi-kpc distance whereas a hadronic scenario would preferentially locate this object at distances of < 1 kpc where the density of target material is higher

Pasture Management Relevant Behaviour of Yaks (Bosgrunniens)

After a decline in yak populations in Central Asia, efforts have been made for several years to rebuild them. In that context, the ecological demands of the alpine landscape must be taken into account. The aim of the studies was to analyse the behaviour of yak cows in short time intervals and to deduce which sub-areas the yaks prefer more or less strongly, which altitudes in the mountains the animals visit in the course of a year, which distances they cover in summer and winter and which factors influence their grazing behaviour. The investigations were carried out on yaks in eastern Kyrgyzstan, Tian Shan Mountains. In three experimental years, 12 Yak cows were equipped with GPS receivers. The positions of the animals on the pastureland were recorded in an interval of 15 minutes. On this basis the home range as well as the walked distances, whereabouts and times (preferences) could be determined. The behaviour of the yaks depends on various factors, which are mainly related to the large grazing area: the variation in the yield of pasture, the different geographical conditions and the seasonal weather conditions. The investigations showed that the behaviour of the animals is strongly influenced by the seasons. This refers to the use of areas and altitudes as well as to movement behaviour. It was found that certain pastures are permanently more frequented than others are. The locomotion of the yaks is more pronounced in winter than in summer. This is because in winter the animals have to go long distances in search of food. Detailed knowledge of yak behaviour can help to improve pasture management in the high alpine region in order to use natural resources sustainably

Interpretation of transverse tune spectra in a heavy-ion synchrotron at high intensities

Two different tune measurement systems have been installed in the GSI heavy-ion synchrotron SIS-18. Tune spectra are obtained with high accuracy using these fast and sensitive systems. Besides the machine tune, the spectra contain information about the intensity dependent coherent tune shift and the incoherent space charge tune shift. The space charge tune shift is derived from a fit of the observed shifted positions of the synchrotron satellites to an analytic expression for the head-tail eigenmodes with space charge. Furthermore, the chromaticity is extracted from the measured head-tail mode structure. The results of the measurements provide experimental evidence of the importance of space charge effects and head-tail modes for the interpretation of transverse beam signals at high intensity

Unidentified Galactic High-Energy Sources as Ancient Pulsar Wind Nebulae in the light of new high energy observations and the new code

In a Pulsar Wind Nebula (PWN), the lifetime of inverse Compton (IC) emitting electrons exceeds the lifetime of its progenitor pulsar (as well as its shell-type remnant), but it also exceeds the age of those that emit via synchrotron radiation. Therefore, during its evolution, the PWN can remain bright in IC so that its GeV-TeV gamma-ray flux remains high for timescales much larger (for 10^5 - 10^6 yrs) than the pulsar lifetime and the X-ray PWN lifetime. In this scenario, the magnetic field in the cavity induced by the wind of the progenitor star plays a crucial role. This scenario is in line with the discovery of several unidentified or "dark" sources in the TeV gamma-ray band without X-ray counterparts; and it is also finding confirmation in the recent discoveries at GeV gamma rays. Moreover, these consequences could be also important for reinterpreting the detection of starburst galaxies in the TeV gamma-ray band when considering a leptonic origin of the gamma-ray signal. Both theoretical aspects and their observational proofs will be discussed, as well as the first results of our new modeling code.Comment: Proceedings of the 5th International Symposium on High-Energy Gamma-Ray Astronomy (Gamma2012