Found 62 talks archived in Particle astrophysics, physical data and processes

There is a "Warped side" of our universe, consisting of objects and phenomena that are made solely or largely from warped spacetime. Examples are black holes, singularities (inside black holes and in the big bang), and cosmic strings. Numerical-relativity simulations are revolutionizing our understanding of what could exist on our universe's Warped Side; and gravitational-wave observations (LIGO, VIRGO, LISA, ...) will reveal what phenomena actually do exist on the Warped Side, and how they behave.

Over the next decade or so, the gravitational-wave window onto the Universe will be opened in four frequency bands that span 22 orders of magnitude: The high-frequency band, 10 to 10,000 Hz (ground-based interferometers such as LIGO and VIRGO), the low-frequency band, 10^-5 to 0.1 Hz (the space-based interferometer LISA), the very-low frequency band, 10^-9 to 10^-7 Hz (pulsar timing arrays), and the extremely-low-frequency band, 10^-18 to 10^-16 Hz (polarization of the cosmic microwave background). This lecture will describe these four bands, the detectors that are being developed to explore them, and what we are likely to learn about black holes, neutron stars, white dwarfs and early-universe exotica from these detectors' observations.

I present some recent results from our Optical and NIR studies of five short period low-mass X-ray binaries (LMXB's; X1822-371, X1957+115, UW CrB, X1916-05 and X0614+091). Optical photometry and spectroscopy reveal some surprising results on the geometry and evolution of accretions discs in LMXB's. Based on our data, it is increasingly clear that accretion discs in these systems are far from being stable and must undergo substantial precession and/or warping behaviour on timescales less than a day in case of the shortest period systems.

The window of very high energy (VHE) gamma-ray astronomy was only opened 20 years ago by the first observation of TeV gamma-rays from the CRAB nebula. Since then the field is rapidly expanding and we are approaching the first 100 VHE sources. In contrast to the many orders of magnitude larger flux of charged VHE Cosmic Rays, gamma-rays can be extrapolated back to their sources, the high energy particle processes mostly in stellar environments and thus allows us to retrieve basic information about the ultra-relativistic universe. In my talk I will shortly describe the gamma-ray production mechanisms related to these ultra relativistic processes, losses during the transport of gamma-rays through the universe and the detection methods. This is followed by a review of classes of gamma ray emitters and the relation to multi-wavelength respectively multi-messenger observations. Because of the very rich findings of the past years some restriction to highlight observations have to be made. The talk concludes with an outlook for the next years including possible prospects to build the so-called North-CTA (Cherenkov Telescope Array) on the Canary Islands.

History: astroparticle physics emerged from particle physics and connects it to astrophysics. Early particle physics was based on cosmic ray studies. The 1930s and 1940s were dominated by the discovery of new particles (positron, muon, pion) and the problems of their identification. In the 1950s, the era of the big accelerators began. Recent astroparticle physics started in the 1980s, with solar neutrino measurements and the investigation of cosmic rays by means of particle detectors.