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6-8 September 2017
Staszic Palace, Warsaw, Poland
Europe/Warsaw timezone

Spectroscopy is a major tool of astrophysics. Then, the X-ray spectroscopy is a major tool of high-energy astrophysics. It can provide us with the temperature, density, velocity and gravitational redshift of the emitting and absorbing plasmas. We propose a 3-day AHEAD ( workshop on this subject in Warsaw, Poland, during 6–8 September 2017. The maximum number of participants is 90. The main organizers of the workshop are Agata Różańska and Andrzej Zdziarski.

X-ray spectroscopy still lags behind e.g. the optical spectroscopy in energy resolution, but most spectral lines from highly ionized heavy elements are visible in the X-ray range between 0.1–9.0 keV. This range overlaps with those of the currently working satellites, namely Chandra, XMM-Newton, Astrosat, NuSTAR, Swift, the upcoming missions eROSITA and Athena, and the planned mission Astro-H2. Thus, X-ray observations allow us to study processes taking place in energetic plasmas and not accessible at longer wavelengths. Main types of sources studied by X-ray spectroscopy are clusters of galaxies, supernova remnants, hot stars and their winds, and different types of accreting systems, in particular, active galactic nuclei and binary systems containing compact objects.

The proposed workshop will be devoted to selected aspects of both theoretical and observational X-ray spectroscopy, and, in particular, to the upcoming mission Athena. Athena will provide us with information about the dynamics and distribution of hot matter in the Universe. Thanks to that we will understand how supermassive black holes grow and how hot gas stabilizes clusters of galaxies. X-rays with energies 0.1–9 keV interact with matter producing emission or absorption from ionized heavy elements. Observations of those lines allow us precisely examine heavy elements content and their chemical evolution. With Athena, we will investigate process of matter falling onto supermassive black hole, in particular its relation with outflowing hot winds (galaxy feedback).Apart from more distant objects, Athena will be suitable to study objects in our Galaxy, such as X-ray binary systems and their outflows, coronae of hot stars, and the Galactic Centre.

Some key issues to be discussed during the workshop are:

  • What is the physics of innermost regions of accreting black holes? Where do the reflected and fluorescent photons come from, and what is the location of the primary X-ray source?
  • Winds, outflows and warm absorbers in AGNs. X-ray spectroscopy allows us to determine the conditions in the plasma surrounding the central X-ray source.
  • Winds and outflows are seen also in X-ray binaries. What are the similarities and differences between them and those in AGNs? What are the crucial factors responsible for the differences?
  • Stellar winds in high-mass X-ray binaries, for example in the mysterious source Cyg X-3. Studies of X-ray lines from matter surrounding the compact object can help us to determine whether it contains a neutron star or a black hole.
  • X-ray emission from galaxy clusters as a tool to determine the dynamics of their hot intergalactic gas, feedback, and the cluster mass.