Rubin-LSST

Abstract:

Compact object displays drastic spectral and timing changing from the beginning to the end of an outburst, showing the different efficiencies of accretion processes. Black hole binaries hence exhibit schematically two different states in X-ray spectra: The first dominated by a thermal component and the second by a hard powerlaw shape like. Whereas the hard component is often attributed to the emission of a radiatively inefficient corona, the thermal component is interpreted as the emission of the optically thick accretion disc. The commonly accepted picture suggests that the observed transition between hard and soft states is associated by a drop in the accretion efficiency of the thermal component by a recession of the internal disc radius in hard states. However, recent studies based on relativistically broadened iron line and the thermal component strength analysis would tend to show the presence of the disc in the vicinity of the horizon. By a reanalysis of archive spectra where thermal emission is present, we tracked the values of the disc radii during outbursts among several sources. Indeed, whereas a constant inner radius would imply that the disc luminosity should monotonically depends on the temperature, we show that this relationship seems to deviate at the lowest luminosities. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.

Abstract:

In order to understand the formation and subsequent evolution of galaxies one must first distinguish between the two main morphological classes of massive systems: spirals and early-type systems. This paper introduces a project, Galaxy Zoo, which provides visual morphological classifications for nearly one million galaxies, extracted from the Sloan Digital Sky Survey (SDSS). This achievement was made possible by inviting the general public to visually inspect and classify these galaxies via the internet. The project has obtained more than 4 × 107 individual classifications made by ∼10 5 participants. We discuss the motivation and strategy for this project, and detail how the classifications were performed and processed. We find that Galaxy Zoo results are consistent with those for subsets of SDSS galaxies classified by professional astronomers, thus demonstrating that our data provide a robust morphological catalogue. Obtaining morphologies by direct visual inspection avoids introducing biases associated with proxies for morphology such as colour, concentration or structural parameters. In addition, this catalogue can be used to directly compare SDSS morphologies with older data sets. The colour-magnitude diagrams for each morphological class are shown, and we illustrate how these distributions differ from those inferred using colour alone as a proxy for morphology. © 2008 RAS.

Abstract:

High energy astrophysics has made good use of combined high energy (X-ray, g-ray) and radio observations to uncover connections between outbursts, accretion, particle acceleration and kinetic feedback to the local ambient medium. In the field of microquasars the connections have been particularly important. However, radio astronomy has been relying on essentially the same facilities for the past ∼ 25 years, whereas high-energy astrophysics, in particular space-based research, has had a series of newer and more powerful missions. In the next fifteen years this imbalance is set to be redressed, with a whole familiy of new radio facilities under development en route to the Square Kilometre Array (SKA) in the 2020s. In this brief review I will summarize these future prospects for radio astronomy, and focus on possibly the most exciting of the new facilities to be built in the next decade, the Low Frequency Array LOFAR, and its uses in high energy astrophysics. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial- ShareAlike Licence.

Abstract:

High energy astrophysics has made good use of combined high energy (X-ray, g-ray) and radio observations to uncover connections between outbursts, accretion, particle acceleration and kinetic feedback to the local ambient medium. In the field of microquasars the connections have been particularly important. However, radio astronomy has been relying on essentially the same facilities for the past ∼ 25 years, whereas high-energy astrophysics, in particular space-based research, has had a series of newer and more powerful missions. In the next fifteen years this imbalance is set to be redressed, with a whole familiy of new radio facilities under development en route to the Square Kilometre Array (SKA) in the 2020s. In this brief review I will summarize these future prospects for radio astronomy, and focus on possibly the most exciting of the new facilities to be built in the next decade, the Low Frequency Array LOFAR, and its uses in high energy astrophysics. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial- ShareAlike Licence.