# Differences

This shows you the differences between two versions of the page.

joint [2018/07/03 10:40]
henrik
joint [2019/02/18 16:18] (current)
marta [Seminar calendar]
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====Seminar calendar==== ====Seminar calendar====

+
+__**Winter term 18/19:**__
+
+== 14th March 2019: Journal Club ==
+
+TBA
+
+== 7th March 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==
+
+TBA
+
+== 28th February 2019: Journal Club ==
+
+TBA
+
+== 21st February 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==
+
+Ana Marta Pinho (ITP, Universität Heidelberg) - TBA
+
+
+== 14th February 2019: Journal Club ==
+
+Julius Wons \\
+
+Using a black hole to weigh light: can the Event Horizon Telescope yield new information about the photon rest mass? \\
+Robert P. Cameron \\
+ePrint: arxiv 1902.02209 \\
+
+Jiaming Zhao \\
+
+Cosmological constrains from the Hubble diagram of quasars at high redshifts \\
+Guido Risaliti and Elizabeta Lusso \\
+ePrint: arXiv: 1811.02590 \\
+
+Oliver Piattella \\
+
+On the cosmological problem \\
+Lucas Lombrasier \\
+ePrint: arXiv: 1901.08588 \\
+
+
+== 7th February 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==
+
+Manuel Wittner (ITP, Universität Heidelberg) - "​Introduction to flux compactifications and moduli stabilization"​
+
+Kaluza-Klein compactifications are the bridge between 10D string theory and our 4D world. Through the large number of possibilities of this compactified internal space, a vast landscape of string vacua arises, one of which might represent our Universe. In this talk I will introduce basic knowledge about flux compactifications and the stabilization of moduli, which are necessary steps in order to obtain realistic 4D models.
+
+
+== 31st January 2019: Journal Club ==
+
+Ana Marta Pinho \\
+
+Could Solar Radiation Pressure Explain '​Oumuamua'​s Peculiar Acceleration?​ \\
+Shmuel Bialy, Abraham Loeb \\
+ePrint: arXiv: 1810.11490 \\
+
+Xuewen Liu \\
+
+On the road to per-cent accuracy: nonlinear reaction of the matter power spectrum to dark energy and modified gravity \\
+Matteo Cataneo, Lucas Lombriser, Catherine Heymans, Alexander Mead, Alexandre Barreira, Sownak Bose, Baojiu Li \\
+ePrint: arXiv: 1812.05594 \\
+
+== 24th January 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==
+
+Salvador Ramirez (ITP, Universität Heidelberg) - "​Deser-Woodard Model and its Reconstruction Problem" ​
+
+
+Nonlocal modifications of gravity arise when one attempts to see the effects of radiative corrections at the classical level. These corrections are often impractical,​ they are difficult to calculate and depend on the method used and assumptions about the source of the corrections. To overcome this we can take a top-down approach, and construct an action with nonlocal terms based on their properties. Deser-Woodard model follows this approach and constructs an action with one of the simplest nonlocal terms and an arbitrary function. We will discuss the reconstruction problem of this model and provide a method to reproduce any given background. Since the model differs with $\Lambda$CDM at the perturbation level, we can test the model with observational data.
+
+== 17th January 2019: Journal Club ==
+
+Jiaming Zhao \\
+
+KiDS+GAMA: Constraints on Horndeski gravity from combined large-scale structure probes \\
+Alessio Spurio Mancini, Fabian Köhlinger, Benjamin Joachimi, Valeria Pettorino, Björn Malte Schäfer, Robert Reischke, Samuel Brieden, Maria Archidiacono et al. \\
+ePrint: arXiv: 1901.03686 \\
+
+Julius Wons \\
+
+Melanopogenesis:​ Dark Matter of (almost) any Mass and Baryonic Matter from the Evaporation of Primordial Black Holes weighing a Ton (or less)  \\
+Logan Morrison, Stefano Profumo, Yan Yu \\
+ePrint: arXiv: 1812.10606 \\
+
+== 10th January 2019: Selected topics in theory and observations of Dark Energy (Tunch) ==
+
+Xuewen Liu (Institute of Theoretical Physics, CAS, Peking) - Cultural Tunch
+
+
+== 3rd January 2019: Journal Club ==
+
+Christmas break
+
+== 27th December 2018: Selected topics in theory and observations of Dark Energy (Tunch) ==
+
+Christmas break
+
+== 20th December 2018: Journal Club ==
+
+Collective Discussions
+
+== 13th December 2018: Selected topics in theory and observations of Dark Energy (Tunch) ==
+
+Collective Discussions
+
+== 6th December 2018: Journal Club ==
+
+Jiaming Zhao \\
+
+Cosmological parameter constraints for Horndeski scalar-tensor gravity \\
+Johannes Noller, Andrina Nicola \\
+ePrint: arXiv: 1811.12928 \\
+
+Guillem Domenèch \\
+
+Early Dark Energy Can Resolve The Hubble Tension \\
+Vivian Poulin, Tristan L. Smith, Tanvi Karwal, Marc Kamionkowski \\
+ePrint: arXiv: 1811.04083
+
+== 29th November 2018: Selected topics in theory and observations of Dark Energy (Tunch) ==
+
+Collective Discussions
+
+== 22nd November 2018: Journal Club ==
+
+Julius Wons \\
+
+Primordial Black Holes With Multi-Modal Mass Spectra \\
+Bernard Carr, Florian Kuhnel \\
+ePrint: arXiv: 1811.06532 \\
+
+
+Current Signs of Dynamical Dark Energy \\
+Joan Sola Peracaula, Adria Gomez-Valent,​ Javier de Cruz Perez \\
+ePrint: arXiv: 1811.03505.pdf \\
+
+== 15th November 2018: Selected topics in theory and observations of Dark Energy (Tunch) ==
+
+Julius Wons (ITP, Universität Heidelberg) - "Are primordial standard clocks really standard?"​
+
+Excited heavy fields during the creation of the primordial curvature perturbation leave oscillatory patterns in the power spectrum. These patterns can be used to distinguish between different primordial scenarios (inflation, bounce, ...) and are therefore called primordial standard clocks. I will show that this is in general not true if the mass of the heavy field is time dependent or when having non-canonical kinetic terms.
+
+
+== 8th November 2018: Journal Club ==
+
+Manuel Wittner \\
+
+On the Cosmological Implications of the String Swampland \\
+Prateek Agrawal, Georges Obied, Paul J. Steinhardt, Cumrun Vafa \\
+ePrint: arXiv: 1806.09718 \\
+
+Stefano Savastano \\
+
+The Primordial Black Hole Dark Matter - LISA Serendipity \\
+N. Bartolo, V. De Luca, G. Franciolini,​ M. Peloso, A. Riotto \\
+ePrint: arXiv: 1810.12218 \\
+
+Xue-Wen Liu \\
+
+The End of Cosmic Growth \\
+Eric V. Linder, David Polarski \\
+ePrint: arXiv: 1810.10547 \\
+
+
+== 1st November 2018: NO Journal Club/Tunch ==
+
+Public Holiday
+
+
+
+== 25th October 2018: Journal Club ==
+
+Dario Bettoni \\
+
+Dark energy after GW170817, revisited \\
+Edmund J. Copeland, Michael Kopp, Antonio Padilla, Paul M. Saffin, Constantinos Skordis \\
+e-Print: arXiv:​1810.08239
+
+Ana Marta Pinho \\
+
+H0 Tension: Response to Riess et al arXiv:​1810.03526 \\
+Tom Shanks, Lucy Hogarth, Nigel Metcalfe \\
+e-Print: arXiv:​1810.07628 ​
+
+
+== 18th October 2018: Selected topics in theory and observations of Dark Energy (Tunch) ==
+
+Manuel Wittner (ITP, Universität Heidelberg) - Cultural Tunch
+
+
+__**Summer term 18:**__

== 19th July 2018: Journal Club == == 19th July 2018: Journal Club ==

Collective Journal Club Collective Journal Club
-

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arXiv 1804.09206 arXiv 1804.09206

+
+__**Winter term 17/18:**__

== 27th March 2018: Selected topics in theory and observations of Dark Energy (Tunch) == == 27th March 2018: Selected topics in theory and observations of Dark Energy (Tunch) ==
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Alessio Spurio Mancini - Dark Energy after GW170817 - 1710.05901 Alessio Spurio Mancini - Dark Energy after GW170817 - 1710.05901

-== 18th July : Journal Club ==+__**Summer term 17:**__
+
+== 18th July 2017: Journal Club ==

-== 11th July : Selected topics in theory and observations of Dark Energy (Tunch) ==+== 11th July 2017: Selected topics in theory and observations of Dark Energy (Tunch) ==
Martin Pauly (ITP, Heidelberg) - "​Predictions of renormalized Higgs inflation"​ Martin Pauly (ITP, Heidelberg) - "​Predictions of renormalized Higgs inflation"​

Abstract: Higgs inflation is a model, that allows to explain inflation with the standard model degrees of freedom by introducing an additional coupling between the Higgs field and gravity. In this talk, I am going to explore the influence of the running of the standard model couplings on the observational predictions of Higgs inflation. In particular, the running of the Higgs-self-coupling and sudden changes in that coupling will be important. These sudden changes can be induced by the effective-field-theory nature of Higgs inflation. I will show that as long as the coupling stays sufficiently large in the inflationary region the predictions are insensitive to the running and become sensitive once the coupling approaches the critical point. Abstract: Higgs inflation is a model, that allows to explain inflation with the standard model degrees of freedom by introducing an additional coupling between the Higgs field and gravity. In this talk, I am going to explore the influence of the running of the standard model couplings on the observational predictions of Higgs inflation. In particular, the running of the Higgs-self-coupling and sudden changes in that coupling will be important. These sudden changes can be induced by the effective-field-theory nature of Higgs inflation. I will show that as long as the coupling stays sufficiently large in the inflationary region the predictions are insensitive to the running and become sensitive once the coupling approaches the critical point.

-== 4th July : Journal Club ==+==  4th July 2017: Journal Club ==

Caroline Heneka \\ Caroline Heneka \\
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arXiv:​1705.04861 arXiv:​1705.04861

-== 27th June : Selected topics in theory and observations of Dark Energy (Tunch) ==+== 27th June 2017: Selected topics in theory and observations of Dark Energy (Tunch) ==

​Cornelius Rampf (ITP, Heidelberg University ) - "​Shell-crossing in quasi one-dimensional flow "  ​Cornelius Rampf (ITP, Heidelberg University ) - "​Shell-crossing in quasi one-dimensional flow "
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Abstract: So far exact analytic solutions to the cosmological fluid equations existed for initial data that only depend on one space variable. Exact solutions (until shell-crossing) play an important role in cosmology, not only because they are simple but because the breakdown of smooth 3D solution through the development of infinite density caustics begins generically as an almost 1D phenomenon with the formation of pancakes. I present recent work on quasi-one-dimensional (Q1D) flow that depends on all three coordinates but differs only slightly from a strictly 1D flow, thereby allowing a perturbative treatment of shell-crossing using the Euler-Poisson equations written in Lagrangian coordinates. The signature of shell-crossing is then just the vanishing of the Jacobian of the Lagrangian map, a regular perturbation problem. In essence, the problem of the first shell-crossing,​ which is highly singular in Eulerian coordinates,​ has been desingularized by switching to Lagrangian coordinates,​ and can then be handled by perturbation theory. All-order recursion relations are obtained for the time-Taylor coefficients of the displacement field, and it is shown that the Taylor series has an infinite radius of convergence. This allows the determination of the time and location of the first shell-crossing,​ which is generically shown to be taking place earlier than for the unperturbed 1D flow. Abstract: So far exact analytic solutions to the cosmological fluid equations existed for initial data that only depend on one space variable. Exact solutions (until shell-crossing) play an important role in cosmology, not only because they are simple but because the breakdown of smooth 3D solution through the development of infinite density caustics begins generically as an almost 1D phenomenon with the formation of pancakes. I present recent work on quasi-one-dimensional (Q1D) flow that depends on all three coordinates but differs only slightly from a strictly 1D flow, thereby allowing a perturbative treatment of shell-crossing using the Euler-Poisson equations written in Lagrangian coordinates. The signature of shell-crossing is then just the vanishing of the Jacobian of the Lagrangian map, a regular perturbation problem. In essence, the problem of the first shell-crossing,​ which is highly singular in Eulerian coordinates,​ has been desingularized by switching to Lagrangian coordinates,​ and can then be handled by perturbation theory. All-order recursion relations are obtained for the time-Taylor coefficients of the displacement field, and it is shown that the Taylor series has an infinite radius of convergence. This allows the determination of the time and location of the first shell-crossing,​ which is generically shown to be taking place earlier than for the unperturbed 1D flow.

-== 20th June : Journal Club ==+== 20th June 2017: Journal Club ==

Caroline Heneka \\ Caroline Heneka \\
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arXiv:​1706.05205 ​ arXiv:​1706.05205 ​

-== 13th June : Selected topics in theory and observations of Dark Energy (Tunch) ==+== 13th June 2017: Selected topics in theory and observations of Dark Energy (Tunch) ==

Santiago Casas (ITP, Heidelberg University) - "​Non-linear structure formation"​ Santiago Casas (ITP, Heidelberg University) - "​Non-linear structure formation"​

-==  6th June : NO Journal Club on this day ==+==  6th June 2017: NO Journal Club on this day ==

-== 30th May : Selected topics in theory and observations of Dark Energy (Tunch) ==+== 30th May 2017: Selected topics in theory and observations of Dark Energy (Tunch) ==

Javier Rubio (ITP, Heidelberg University) - "Scale invariance: connecting inflation and dark energy"​ Javier Rubio (ITP, Heidelberg University) - "Scale invariance: connecting inflation and dark energy"​
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Abstract: Inflation and dark energy share many essential properties. I will show that these two eras can be accommodated into a common framework based on scale invariance. I will discuss the phenomenological consequences of two scenarios based on i) exact scale symmetry and ii) broken scale invariance with symmetry resurgence at UV and IR fixed points. Abstract: Inflation and dark energy share many essential properties. I will show that these two eras can be accommodated into a common framework based on scale invariance. I will discuss the phenomenological consequences of two scenarios based on i) exact scale symmetry and ii) broken scale invariance with symmetry resurgence at UV and IR fixed points.

-== 23rd May : Journal Club ==+== 23rd May 2017: Journal Club ==

Henrik Nersisyan \\ Henrik Nersisyan \\
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-== 16th May : Selected topics in theory and observations of Dark Energy (Tunch) ==+== 16th May 2017: Selected topics in theory and observations of Dark Energy (Tunch) ==

Alefe Almeida(ITP,​ Heidelberg University) - " A method for evaluating models that use galaxy rotation curves to derive matter density profiles"​ Alefe Almeida(ITP,​ Heidelberg University) - " A method for evaluating models that use galaxy rotation curves to derive matter density profiles"​
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Abstract: There are some approaches, either based on GR or modified gravity that use galaxy rotation to derive the matter density of the corresponding galaxy. In this work, we proposed a test for evaluating them. Abstract: There are some approaches, either based on GR or modified gravity that use galaxy rotation to derive the matter density of the corresponding galaxy. In this work, we proposed a test for evaluating them.

-== 9th May  Journal Club ==+== 9th May 2017: Journal Club ==

Kevin Wolz Kevin Wolz
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arXiv:​1701.08724 ​ arXiv:​1701.08724 ​

-== 25th April : Selected topics in theory and observations of Dark Energy (Tunch) ==+== 25th April 2017: Selected topics in theory and observations of Dark Energy (Tunch) ==

Yves Dirian (Geneva University ) - "A numerical relativity scheme for cosmological simulations"​  Yves Dirian (Geneva University ) - "A numerical relativity scheme for cosmological simulations"​
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Abstract: I present a new 3+1 integration scheme which allows one to pass an adaptation of the robustness test to the cosmological context, at least in the case of General Relativity with a pressureless perfect fluid field. As an interesting by-product of this construction,​ a novel constraint-damping method is obtained. ​ Abstract: I present a new 3+1 integration scheme which allows one to pass an adaptation of the robustness test to the cosmological context, at least in the case of General Relativity with a pressureless perfect fluid field. As an interesting by-product of this construction,​ a novel constraint-damping method is obtained. ​

-== 18th April : Journal Club ==+== 18th April 2017: Journal Club ==

Viviana Niro Viviana Niro