Ruprecht Karls Universität Heidelberg

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joint [2019/05/15 14:43]
manuel [Seminar calendar]
joint [2019/07/04 10:38] (current)
marta [Seminar calendar]
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 __**Summer term 19:**__ __**Summer term 19:**__
 +
 +
 +== 26th September 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==
 +
 +TBA
 +
 +== 19th September 2019: Journal Club ==
 +
 +TBA
 +
 +== 25th July 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==
 +
 +TBA
 +
 +== 18th July 2019: Journal Club ==
 +
 +TBA
 +
 +== 11th July 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==
 +
 +Jakob Henrichs - TBA
 +
 +== 4th July 2019: Journal Club ==
 +
 +Oliver Fabio Piattella \\
 +
 +Can the quantum vacuum fluctuations really solve the cosmological constant problem? \\
 +Gabriel R. Bengochea, Gabriel León, Elias Okon, Daniel Sudarsky \\
 +[[ https://​arxiv.org/​abs/​1906.05406 | view arXiv ]]
 +
 +== 25th June 2019, PW 12, Room 060 (NOTE UNUSUAL DATE AND LOCATION): Selected topics in theory and observations of Dark Energy (Tunch) ==
 +
 +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 +outdated, a quick review to the many papers that address this pivotal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 ==
 +
 +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) ==
 +
 +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 ==
 +
 +Leonardo Giani \\
 +
 +Is Gravity Actually the Curvature of Spacetime? \\
 +Sebastian Bahamonde, Mir Faizal \\
 +[[https://​arxiv.org/​abs/​1905.04372 | view arXiv ]] \\
 +
 +Ana Marta Pinho \\
 +
 +Black hole shadow as a standard ruler in cosmology \\
 +Oleg Yu. Tsupko, Zuhui Fan, Gennady S. Bisnovatyi-Kogan \\
 +[[https://​arxiv.org/​abs/​1905.10509 | view arXiv ]] \\
 +
  
 == 29th May 2019, PW 12, Room 060 (NOTE UNUSUAL DATE AND LOCATION): Selected topics in theory and observations of Dark Energy (Tunch) == == 29th May 2019, PW 12, Room 060 (NOTE UNUSUAL DATE AND LOCATION): Selected topics in theory and observations of Dark Energy (Tunch) ==
  
-Oliver Piattella (UFES, Brazil; visitor at ITP, Universität Heidelberg) - TBA+Oliver Piattella (UFES, Brazil; visitor at ITP, Universität Heidelberg) - "​Neutron stars masses in R^2 gravity"​ 
 + 
 +We investigate the mass-radius (M-R) relation for 
 +neutron stars in f(R) = R + R^2 gravity. We adopt a spherically 
 +symmetric metric and a SLy equation of state. We stress how in f(R) 
 +gravity it is possible to define mass in many inequivalent ways which 
 +are nonetheless all equivalent in General Relativity. We investigate 
 +the role of the extra scalar degree of freedom in the definition of 
 +the masses and in the features of the M-R relation.
  
 == 23rd May 2019: Journal Club == == 23rd May 2019: Journal Club ==
  
-TBA+Adrià Gomez-Valent \\ 
 + 
 +Recasting H0 tension as OmegaM tension at low z \\ 
 +Eoin Ó Colgáin \\ 
 +[[https://​arxiv.org/​abs/​1903.11743 | view arXiv ]] \\ 
 + 
 +Leonardo Giani \\ 
 + 
 +How to Hide a Cosmological Constant \\ 
 +S. Carlip \\ 
 +[[https://​arxiv.org/​abs/​1905.05216 | view arXiv ]] 
  
 == 16th May 2019: Selected topics in theory and observations of Dark Energy (Tunch) == == 16th May 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==

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