Search the repository

A+ | A- | | SLO | ENG

Abstract: The Large Synoptic Survey Telescope (LSST) will produce a multi-colour survey of 25000 square deg of the Southern sky during its 10 years of operations. It will observe over 20 billion galaxies and a similar number of stars, map the Solar System and the Milky Way, and probe dark matter and dark energy. In addition, it will discover thousands of transients every night, including new classes of objects, which have not yet been observed. Due to its large coverage of the sky it will be a perfect tool for the search of rare Tidal Disruption Events (TDEs), which occur when a star passes close by a supermassive black hole and gets disrupted by its tidal force. Afterwards the stellar debris fall back to the black hole, initially at a rate exceeding the Eddington rate, producing an outflow, which releases a flare of energy. When the fallback rate subsides below the Eddington rate, the gas accretes onto the black hole via accretion disk. The LSST simulation framework enables us to simulate observations of different types of objects with the LSST. In this work, we include TDEs in the LSST simulation framework, estimate the number of detected TDEs, and simulate their light curves using a theoretical model, which predicts a t^(-2.6) light curve decline with time in the outflow phase and a t^{-0.4} decline in the disk phase. We also take a closer look at the distribution of the detected TDEs over cosmological redshift and black hole mass.
Keywords: Astronomical observations, Large Synoptic Survey Telescope, Tidal Disruption Events, Black Holes, simulations
Published in RUNG: 17.10.2017; Views: 5488; Downloads: 0
This document has many files! More...

Keywords: Cherenkov Telescope Array (CTA), Large-Sized Telescope (LST), imaging camera, readout system
Published in RUNG: 24.03.2016; Views: 5943; Downloads: 368
Full text (927,35 KB)

Keywords: Cherenkov Telescope Array (CTA), Large Size Telescopes (LST), optical system, active mirror control system
Published in RUNG: 21.03.2016; Views: 5621; Downloads: 269
Full text (1,10 MB)

Keywords: Cherenkov Telescope Array (CTA), Large Size Telescopes (LST), design requirements, element prototyping, installation and operation plans
Published in RUNG: 16.03.2016; Views: 5258; Downloads: 226
Full text (5,17 MB)

Abstract: The large-scale distribution of arrival directions of high-energy cosmic rays carries major clues to understanding their origin. The Pierre Auger Collaboration have implemented different analyses to search for dipolar and quadrupolar anisotropies in different energy ranges spanning four orders of magnitude. A common phase ≈270◦ of the first harmonic modulation in right-ascension was found in adjacent energy intervals below 1 EeV, and another common phase ≈100◦ above 4 EeV. A constancy of phase measurements in ordered energy intervals originating from a genuine anisotropy is expected to appear with a smaller number of events than those needed to achieve significant amplitudes. This led us to design a prescribed test aimed at establishing whether this consistency in phases is real at 99% CL. The test required a total independent exposure of 21,000 km2 sr yr. We report on the status of this prescription. We also report the results of the search for a dipole anisotropy for cosmic rays with energies above 4 EeV using events with zenith angles between 60◦ and 80◦. Compared to previous analyses of events with zenith angles smaller than 60◦, this extension increases the size of the data set by 30%, and enlarges the fraction of exposed sky from 71% to 85%. The largest departure from isotropy is found in the energy range above 8 EeV, with an amplitude for the first harmonic in right ascension r1 = (4.4 ± 1.0) × 10[sup]−2, that has a chance probability P(≥ r1) = 6.4×10[sup]−5, reinforcing the hint previously reported with vertical events alone.
Keywords: high-energy cosmic rays large-scale distribution anisotropy studies Pierre Auger Observatory
Published in RUNG: 02.03.2016; Views: 6454; Downloads: 243
Full text (862,90 KB)