Número de entradas: **21**

### On the trace anomaly of a Weyl fermion

**Inicio:** 12:00h

**Ponente:** Fiorenzo Bastianelli (University of Bologna and INFN, Bologna)

**Lugar:** Conference Room

**Inicio:** 12:00h

**Ponente:** Fiorenzo Bastianelli (University of Bologna and INFN, Bologna)

**Lugar:** Conference Room

We discuss the status of the trace anomaly of a massless chiral fermion in a curved background, which we calculate again using a Pauli-Villars regularization. The motivation of our analysis stems from recent claims that the trace anomaly might contain a term proportional to the topological Pontryagin density of the curved background. We do not find such a term in the trace anomaly.
### Cosmological Constant and Renormalization of Gravity

**Inicio:** 11:00h

**Ponente:** Shinichi Nojiri (Kobayashi-Maskawa-Institute, Nagoya University, Japan)

**Lugar:** Conference Room

**Inicio:** 11:00h

**Ponente:** Shinichi Nojiri (Kobayashi-Maskawa-Institute, Nagoya University, Japan)

**Lugar:** Conference Room

We propose several covariant models which may solve one of the problems in the cosmological constant.
### Geometric Foundations of Gravity - An overview of research in Tartu

**Inicio:** 12:00h

**Ponente:** Manuel Hohmann (Füüsika Instituut Tartu Ülikool)

**Lugar:** D2/20

**Inicio:** 12:00h

**Ponente:** Manuel Hohmann (Füüsika Instituut Tartu Ülikool)

**Lugar:** D2/20

We present a systematic analysis of the dynamics of flat Friedmann-Lema\^{i}tre-Robertson-Walker cosmological models with radiation and dust matter in generalized teleparallel f(T) gravity. We show that the cosmological dynamics of this model is fully described by a function W(H) of the Hubble parameter, which is constructed from the function f(T). I will also give an overview of research in Tartu.
### MSSM-inspired multifield inflation

**Inicio:** 12:00h

**Ponente:** Sergey Vernov ; Ekaterina Pozdeeva

**Lugar:** Alberto Lobo Conference Room S1-01

**Inicio:** 12:00h

**Ponente:** Sergey Vernov ; Ekaterina Pozdeeva

**Lugar:** Alberto Lobo Conference Room S1-01

We analyze the inflationary scenarios which could be induced by the two-Higgs-doublet potential of the Minimal Supersymmetric Standard Model (MSSM) where five scalar fields have nonminimal couplings to gravity. Observables following from such MSSM-inspired multifield inflation are calculated and a number of consistent inflationary scenarios are constructed. Cosmological evolution with different initial conditions for the multifield system leads to consequences fully compatible with observational data on the spectral index and the tensor-to-scalar ratio.
### Modeling the distribution of HI in the post-reionization era: Cosmology with SKA

**Inicio:** 12:30h

**Ponente:** Francisco Villaescusa-Navarro (Center for Computational Astrophysics (Simons Foundation, New York))

**Lugar:** Sala Alberto Lobo

**Inicio:** 12:30h

**Ponente:** Francisco Villaescusa-Navarro (Center for Computational Astrophysics (Simons Foundation, New York))

**Lugar:** Sala Alberto Lobo

I will discuss the possibility of sampling the large-scale structure of the Universe using radio-telescopes through the 21cm intensity mapping technique in the post-reionization era. I will show how to model the spatial distribution of cosmic neutral hydrogen using numerical simulations and the constraints that the Square Kilometre Array (SKA) instrument will place on warm dark matter and massive neutrinos. I will also examine how well the SKA1-MID instrument will be able to detect the BAO. Finally, I will discuss the potential problems such as the presence of bright foregrounds and the role of instrument calibration.
### Sufficient Statistics for Cosmology

**Inicio:** 12:00h

**Ponente:** Istvan Szapudi (Institute of Astronomy (University of Hawai))

**Lugar:** Sala Alberto Lobo

**Inicio:** 12:00h

**Ponente:** Istvan Szapudi (Institute of Astronomy (University of Hawai))

**Lugar:** Sala Alberto Lobo

Sufficient statistics extract all the cosmological information from a large scale structure survey, thus they sharpen constraints available from traditional statistics, such as power spectrum. The log-power spectrum, the simplest among the approximations studies to date, will double the effective survey volume of future surveys, such as EUCLID and WFIRST. I will review the theory of sufficient statistics, forecasting, and recent results on predicting the log power spectrum.
### Redshift-space distortions - Measuring the growth rate of structures from the final VIPERS dataset

**Inicio:** 12:00h

**Ponente:** Andrea Pezzotta (Brera Observatory (Milan))

**Lugar:** Sala Alberto Lobo

**Inicio:** 12:00h

**Ponente:** Andrea Pezzotta (Brera Observatory (Milan))

**Lugar:** Sala Alberto Lobo

Observations of Type Ia Supernovae combined with the anisotropies of the Cosmic Microwave Background have reinforced the conclusion that our Universe is dominated by a repulsive dark energy capable of driving the observed accelerated expansion. Unfortunately this scenario is highly degenerate with the more radical breakdown of General Relativity on cosmological scales, since modified gravity can predict the same expansion history H(z) as in a LCDM (dark energy+ GR). In principle, this degeneracy can be lifted by measuring the growth rate of structure, which depends on the specific theory describing gravity. One of the most reliable probes of the growth of structures is provided by redshift-space distortions (RSD). These arise when measured redshifts, that contain also the contribution of galaxy peculiar velocities, are used as distance proxy, introducing an anisotropy in the measured clustering. Unfortunately, extracting the linear RSD signal from galaxy redshift surveys is non-trivial, because much of the RSD signal lies on quasi-linear and non-linear scales. This requires a strong effort to properly model non-linear clustering and velocities. Here I present measurements of the growth rate of structure from the new data of the complete VIPERS survey. We implement and improve specific techniques and models, both to correct for any defects inside the measured 2PCF and also to understand the impact of different RSD models on the recovery of the growth rate. Measurements of the growth rate from VIPERS are in agreement with standard cosmology predictions assuming Einstein gravity in a LCDM background, although they still do not exclude a variety of models in which gravity is modified on cosmic scales
### Photometric redshift estimation for precision cosmology

**Inicio:** 10:30h

**Ponente:** markus rau (LMU (Munich))

**Lugar:** Sala Alberto Lobo

**Inicio:** 10:30h

**Ponente:** markus rau (LMU (Munich))

**Lugar:** Sala Alberto Lobo

Abstract: Photometric redshift uncertainty is one of the dominant sources of systematic error in ongoing and future large area photometric surveys like DES, KiDS, LSST and Euclid. Accurate photometric redshift validation and treatment of redshift uncertainty is therefore a vital requirement to enter the era of precision cosmology using these surveys. In my talk I will discuss these challenges and present a Machine Learning based photometric redshift methodology, that uses synthetic data from simulations, templates and spectroscopic data to produce highly accurate photometric redshift predictions. In combination with the Smoothed Bootstrap, a specialized resampling technique, it is then possible to incorporate the remaining photometric redshift error into the cosmological parameter constraint.
### Addressing systematic effects in the new generation of galaxy surveys

**Inicio:** 10:30h

**Ponente:** Jonás Chaves Montero (CEFCA (Teruel))

**Lugar:** Sala Alberto Lobo

**Inicio:** 10:30h

**Ponente:** Jonás Chaves Montero (CEFCA (Teruel))

**Lugar:** Sala Alberto Lobo

There is a world-wide effort to unravel the nature of gravity and the expansion history of the Universe. The new generation of cosmological surveys such as DES, PAUS, J-PAS, DESI, LSST, Euclid, WFIRST, etc., will provide tons of data that will no longer be dominated by statistical errors but by systematic uncertainties. I will study the impact of some of these systematic uncertainties on the large-scale structure. I will address baryonic effects using a new implementation of subhalo abundance matching, a model for connecting dark matter haloes with galaxies, that produces the same galaxy clustering as hydrodynamical simulations within statistical errors. Then, I will show the effect of sub-percent redshift uncertainties on the baryonic acoustic oscillations (BAO). I will provide analytical expressions for their effects and I will show how the cosmological information encoded in the BAO is modulated by the interplay of redshift space distortions, redshift errors, bias, and number density of the sample. Finally, I will present ELDAR, a new method for detecting AGN and computing their redshifts in medium- and narrow-band photometric surveys.
### Galaxy formation in the Planck Millennium

**Inicio:** 12:00h

**Ponente:** Carlton Baugh (Durham)

**Lugar:** Sala Alberto Lobo

**Inicio:** 12:00h

**Ponente:** Carlton Baugh (Durham)

**Lugar:** Sala Alberto Lobo

I will give an overview of semi-analytical modelling of galaxy formation, and show how the model predictions are affected by the uncertainty in the modelling of sub-grid physics, as set out in Lacey et al. (2016). I will then show how the model can be used to make predictions for HI intensity mapping experiments.

31

Octubre 2017

Octubre 2017

We discuss the status of the trace anomaly of a massless chiral fermion in a curved background, which we calculate again using a Pauli-Villars regularization. The motivation of our analysis stems from recent claims that the trace anomaly might contain a term proportional to the topological Pontryagin…

We discuss the status of the trace anomaly of a massless chiral fermion in a curved background, which we calculate again using a Pauli-Villars regularization. The motivation of our analysis stems from recent claims that the trace anomaly might contain a term proportional to the topological Pontryagin density of the curved background. We do not find such a term in the trace anomaly.

31

Octubre 2017

Octubre 2017

We propose several covariant models which may solve one of the problems in the cosmological constant.

We propose several covariant models which may solve one of the problems in the cosmological constant.

19

Octubre 2017

Octubre 2017

We present a systematic analysis of the dynamics of flat Friedmann-Lema\^{i}tre-Robertson-Walker cosmological models with radiation and dust matter in generalized teleparallel f(T) gravity. We show that the cosmological dynamics of this model is fully described by a function W(H) of the Hubble parameter,…

We present a systematic analysis of the dynamics of flat Friedmann-Lema\^{i}tre-Robertson-Walker cosmological models with radiation and dust matter in generalized teleparallel f(T) gravity. We show that the cosmological dynamics of this model is fully described by a function W(H) of the Hubble parameter, which is constructed from the function f(T). I will also give an overview of research in Tartu.

27

Septiembre 2017

Septiembre 2017

We analyze the inflationary scenarios which could be induced by the two-Higgs-doublet potential of the Minimal Supersymmetric Standard Model (MSSM) where five scalar fields have nonminimal couplings to gravity. Observables following from such MSSM-inspired multifield inflation are calculated and a number…

We analyze the inflationary scenarios which could be induced by the two-Higgs-doublet potential of the Minimal Supersymmetric Standard Model (MSSM) where five scalar fields have nonminimal couplings to gravity. Observables following from such MSSM-inspired multifield inflation are calculated and a number of consistent inflationary scenarios are constructed. Cosmological evolution with different initial conditions for the multifield system leads to consequences fully compatible with observational data on the spectral index and the tensor-to-scalar ratio.

01

Marzo 2017

Marzo 2017

I will discuss the possibility of sampling the large-scale structure of the Universe using radio-telescopes through the 21cm intensity mapping technique in the post-reionization era. I will show how to model the spatial distribution of cosmic neutral hydrogen using numerical simulations and the constraints…

I will discuss the possibility of sampling the large-scale structure of the Universe using radio-telescopes through the 21cm intensity mapping technique in the post-reionization era. I will show how to model the spatial distribution of cosmic neutral hydrogen using numerical simulations and the constraints that the Square Kilometre Array (SKA) instrument will place on warm dark matter and massive neutrinos. I will also examine how well the SKA1-MID instrument will be able to detect the BAO. Finally, I will discuss the potential problems such as the presence of bright foregrounds and the role of instrument calibration.

16

Febrero 2017

Febrero 2017

Sufficient statistics extract all the cosmological information from a large scale structure survey, thus they sharpen constraints available from traditional statistics, such as power spectrum. The log-power spectrum, the simplest among the approximations studies to date, will double the effective survey…

Sufficient statistics extract all the cosmological information from a large scale structure survey, thus they sharpen constraints available from traditional statistics, such as power spectrum. The log-power spectrum, the simplest among the approximations studies to date, will double the effective survey volume of future surveys, such as EUCLID and WFIRST. I will review the theory of sufficient statistics, forecasting, and recent results on predicting the log power spectrum.

26

Enero 2017

Enero 2017

Observations of Type Ia Supernovae combined with the anisotropies of the Cosmic Microwave Background have reinforced the conclusion that our Universe is dominated by a repulsive dark energy capable of driving the observed accelerated expansion. Unfortunately this scenario is highly degenerate with the…

Observations of Type Ia Supernovae combined with the anisotropies of the Cosmic Microwave Background have reinforced the conclusion that our Universe is dominated by a repulsive dark energy capable of driving the observed accelerated expansion. Unfortunately this scenario is highly degenerate with the more radical breakdown of General Relativity on cosmological scales, since modified gravity can predict the same expansion history H(z) as in a LCDM (dark energy+ GR). In principle, this degeneracy can be lifted by measuring the growth rate of structure, which depends on the specific theory describing gravity. One of the most reliable probes of the growth of structures is provided by redshift-space distortions (RSD). These arise when measured redshifts, that contain also the contribution of galaxy peculiar velocities, are used as distance proxy, introducing an anisotropy in the measured clustering. Unfortunately, extracting the linear RSD signal from galaxy redshift surveys is non-trivial, because much of the RSD signal lies on quasi-linear and non-linear scales. This requires a strong effort to properly model non-linear clustering and velocities. Here I present measurements of the growth rate of structure from the new data of the complete VIPERS survey. We implement and improve specific techniques and models, both to correct for any defects inside the measured 2PCF and also to understand the impact of different RSD models on the recovery of the growth rate. Measurements of the growth rate from VIPERS are in agreement with standard cosmology predictions assuming Einstein gravity in a LCDM background, although they still do not exclude a variety of models in which gravity is modified on cosmic scales

24

Enero 2017

Enero 2017

Abstract: Photometric redshift uncertainty is one of the dominant sources of systematic error in ongoing and future large area photometric surveys like DES, KiDS, LSST and Euclid. Accurate photometric redshift validation and treatment of redshift uncertainty is therefore a vital requirement…

Abstract: Photometric redshift uncertainty is one of the dominant sources of systematic error in ongoing and future large area photometric surveys like DES, KiDS, LSST and Euclid. Accurate photometric redshift validation and treatment of redshift uncertainty is therefore a vital requirement to enter the era of precision cosmology using these surveys. In my talk I will discuss these challenges and present a Machine Learning based photometric redshift methodology, that uses synthetic data from simulations, templates and spectroscopic data to produce highly accurate photometric redshift predictions. In combination with the Smoothed Bootstrap, a specialized resampling technique, it is then possible to incorporate the remaining photometric redshift error into the cosmological parameter constraint.

23

Enero 2017

Enero 2017

There is a world-wide effort to unravel the nature of gravity and the expansion history of the Universe. The new generation of cosmological surveys such as DES, PAUS, J-PAS, DESI, LSST, Euclid, WFIRST, etc., will provide tons of data that will no longer be dominated by statistical errors but by systematic…

There is a world-wide effort to unravel the nature of gravity and the expansion history of the Universe. The new generation of cosmological surveys such as DES, PAUS, J-PAS, DESI, LSST, Euclid, WFIRST, etc., will provide tons of data that will no longer be dominated by statistical errors but by systematic uncertainties. I will study the impact of some of these systematic uncertainties on the large-scale structure. I will address baryonic effects using a new implementation of subhalo abundance matching, a model for connecting dark matter haloes with galaxies, that produces the same galaxy clustering as hydrodynamical simulations within statistical errors. Then, I will show the effect of sub-percent redshift uncertainties on the baryonic acoustic oscillations (BAO). I will provide analytical expressions for their effects and I will show how the cosmological information encoded in the BAO is modulated by the interplay of redshift space distortions, redshift errors, bias, and number density of the sample. Finally, I will present ELDAR, a new method for detecting AGN and computing their redshifts in medium- and narrow-band photometric surveys.

19

Enero 2017

Enero 2017

I will give an overview of semi-analytical modelling of galaxy formation, and show how the model predictions are affected by the uncertainty in the modelling of sub-grid physics, as set out in Lacey et al. (2016). I will then show how the model can be used to make predictions for HI intensity…

I will give an overview of semi-analytical modelling of galaxy formation, and show how the model predictions are affected by the uncertainty in the modelling of sub-grid physics, as set out in Lacey et al. (2016). I will then show how the model can be used to make predictions for HI intensity mapping experiments.

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