Ruprecht Karls Universität Heidelberg

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joint [2019/06/06 10:55]
marta [Seminar calendar]
joint [2019/06/24 13:19] (current)
manuel [Seminar calendar]
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 == 11th July 2019: Selected topics in theory and observations of Dark Energy (Tunch) == == 11th July 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==
  
-TBA+Jakob Henrichs - TBA
  
 == 4th July 2019: Journal Club == == 4th July 2019: Journal Club ==
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 TBA TBA
  
-== 27th June 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==+== 25th June 2019, PW 12, Room 060 (NOTE UNUSUAL DATE AND LOCATION): Selected topics in theory and observations of Dark Energy (Tunch) ==
  
-TBA+Adria Gomez-Valent (ITP, Universität Heidelberg) - "​Quantifying the evidence for the current speed-up of the 
 +Universe with low and intermediate-redshift data. A more 
 +model-independent approach"​ 
 + 
 +According to cosmological low and intermediate-redshift 
 +data, what is the statistical evidence in favor of the current 
 +speed-up of the Universe? Although this question seems to be kind of 
 +outdated, a quick review to the many papers that address this pivotal 
 +question in the literature tells us that the answer is not obvious at 
 +all. Determining the value of the deceleration parameter in the 
 +context of particular cosmological models, concrete parametrizations 
 +of the cosmographical quantities, or even using truncated 
 +cosmographical expansions in which the truncation order is set in an 
 +ad hoc way 
 +can lead to biased estimations of the value of the deceleration 
 +parameter at present, q0, and its uncertainty. In this talk, which is 
 +based on arXiv:​1810.02278,​ JCAP 05 (2019) 026, I present a new 
 +determination of q0 obtained with data from the Pantheon+MCT 
 +compilation of supernovae of Type Ia, cosmic chronometers and baryon 
 +acoustic oscillations. I apply the so-called Weighted Function 
 +Regression method to reconstruct q(z) more model-independently than 
 +many analyses in the literature, improving in this way the usual 
 +cosmograhical approach. We will see, for instance, that using only the 
 +first two data sets the level of evidence for the current positive 
 +acceleration of the universe is only moderate (using Jeffreys'​ scale 
 +and jargon), contrary to the more than 17\sigma-evidence found in the 
 +framework of the standard flat LCDM model. The level of evidence grows 
 +up to the very strong one when BAO data are also considered, giving 
 +rise to q0= -0.60 +- 0.10, with a deceleration-acceleration transition 
 +redshift at z_t = 0.80 +- 0.10. The jerk is also reconstructed,​ 
 +although unfortunately current data is unable to set stringent 
 +constraints to this cosmographical parameter.
  
 == 19th June 2019, PW 12, Room 060 (NOTE UNUSUAL DATE AND LOCATION): Journal Club == == 19th June 2019, PW 12, Room 060 (NOTE UNUSUAL DATE AND LOCATION): Journal Club ==
  
-TBA+Giorgio Laverda \\ 
 + 
 +Strong gravity signatures in the polarization of gravitational waves \\ 
 +S. Shankaranarayanan \\ 
 +[[https://​arxiv.org/​abs/​1905.03943 | view arXiv ]] \\ 
 + 
 +Julius Wons 
 + 
 +Gravitational wave standard sirens and cosmological parameter measurement \\ 
 +Xin Zhang \\ 
 +[[https://​arxiv.org/​abs/​1905.11122 | view arXiv ]] \\
  
 == 13th June 2019: Selected topics in theory and observations of Dark Energy (Tunch) == == 13th June 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==
  
-TBA+Arvid Weyrauch & Manuel Wittner (ITP, Universität Heidelberg) - “Cosmology,​ philosophically speaking” (Collective Discussions)  
 + 
 +As researchers we tend to find answers using the scientific method. However, some questions may not have an answer but still spark a lot of different thoughts and perspectives. In this tunch, we will address some of these questions, from the nature of time to its beginning.
  
 == 6th June 2019: Journal Club == == 6th June 2019: Journal Club ==

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