Seminars
Our seminars take place in the lecture room of the building at
Praha–Sporilov.
Next seminar:
30.10.2017 14:00
David Jones (IAC), and Petr Kabath (ASU)
1) Instituto de Astrofísica de Canarias, La Laguna; 2) Astronomical Institute of the Czech Academy of Sciences, Ondřejov
"Per aspera ad astra simul": an ERAMUS+ collaboration
Abstract
David Jones (IAC), and Petr Kabath (ASU)
"Per aspera ad astra simul": an ERAMUS+ collaboration
The "Per aspera ad astra simul" ("Through difficulties to the stars together") ERASMUS+ programme represents a strategic collaboration between the Instituto de Astrofisica de Canarias (IAC, Spain) and various institutions across the Czech Republic and Slovakia, with unique opportunities for students, postdocs and more senior researchers alike. In this talk, David Jones (via Skype) will introduce the IAC and its observatories, including the Roque de Los Muchachos Observatory - home to the World's largest optical telescope, the Gran Telescopio Canarias or GranTeCan. With Petr Kabath we will also highlight some of the planned activities of the ERASMUS+ programme, including student placements at the IAC and GranTeCan, Summer schools on astronomical observing techniques, and opportunities for Czech and Slovak institutions to host IAC researchers.
01.11.2017 14:00
Sarah Jaffa
Cardiff University, UK
Reading patterns in the sky
Abstract
Sarah Jaffa
Reading patterns in the sky
Star formation is a chaotic process, operating over a range of scales. This makes direct comparison between individual objects, whether observed or simulated, at best very difficult, and in many situations not very useful. We need unbiased statistical measures both to identify and classify the important structures; to enable a quantitative comparison of observed and simulated data; and thereby to reveal the underlying physics. I will describe a range of algorithms for detecting and quantising structure in star forming clouds and star clusters, using statistical and morphological metrics, and illustrate their application to a few representative sources.
13.11.2017 14:00
Robert Williams
Space Telescope Science Institute, Baltimore
The Hubble Deep Field and its Legacy
Abstract
Robert Williams
The Hubble Deep Field and its Legacy
The history of how and why the original Hubble Deep Field was undertaken will be described, including the features that made it unique. The characteristics of subsequent HST deep fields will be explained, including how they helped lead to the discoveries of dark energy, the distribution of dark matter, and the rate of star formation since the Big Bang. The results of all the deep fields combined with recent detailed numerical simulations from supercomputers have now produced a realistic model for galaxy formation and evolution over cosmic time.
Previous seminar:
10.10.2017 14:00
Elias Kammoun
SISSA, Trieste - Italy
Probing the close environment of supermassive black holes through X-ray spectral and temporal approaches
Abstract
Elias Kammoun
Probing the close environment of supermassive black holes through X-ray spectral and temporal approaches
The spin is one of the fundamental observable properties of black holes (BHs). The spin measurement, particularly in active galactic nuclei (AGN), is of great interest for understanding the physical processes on scales ranging from the circumnuclear region out to the host galaxy. Among the various methods used to measure spins of accreting BHs, the detection of a strong relativistic reflection component in the X-ray spectra is potentially the most powerful, and it has been shown to provide robust results mainly in the least obscured sources. It would be then timely to test how reliable the reflection-based BH spin measurements that can be currently achieved are. I will present in the first part of my talk an attempt to answer this question through blind-fitting a set of simulated high-quality XMM-Newton and NuSTAR spectra, considering the most generic configuration of AGN spectra. Our main result shows that, in spite of their quality, single-epoch observations mostly return poor constraints on the actual BH spin value, except for the case of extreme relativistic effects. I will discuss also the possible impact of ATHENA in this field and how these limitations can be overcome.
In the second part of my talk, I will present the "flux-flux plots" method that can provide model-independent clues regarding the X-ray variability of AGN. We applied this method to simultaneous XMM-Newton and NuSTAR observations of MCG-6-30-15 and we were able to identify both a variable and a constant (over >4.5 days) component of the X-ray emission in this source. The variable emission is consistent with a primary plus relativistic reflection that are modified by warm absorption. While the constant emission consists of a blackbody (kT ~ 0.1 keV) responsible of the constant soft excess and a neutral reflection, from distant neutral material, dominating at energies above ~1.6 keV.
If you would like to give a seminar in our group, please contact Petra Sukova or Vladimir Karas.
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