Número de entradas: **25**

### Black holes and other compact objects in metric-affine Ricci-based theories of gravity

**Inicio:** 12:00h

**Ponente:** Diego Rubiera-García (Institute of Astrophysics, University of Lisbon)

**Lugar:** Alberto Lobo room

**Inicio:** 12:00h

**Ponente:** Diego Rubiera-García (Institute of Astrophysics, University of Lisbon)

**Lugar:** Alberto Lobo room

I will discuss recent progress on the existence of black holes and horizonless compact objects in a class of theories constructed out of contractions of the Ricci tensor with the metric, and formulated on a metric-affine approach, where metric and affine connection are independent degrees of freedom. These theories yield ghost-free second-order field equations and contain just the two standard tensor polarization models of the gravitational field that propagate at the speed of light, thus allowing these theories to survive the slaughter on modified theories of gravity resulting from the beginning of multimessenger astronomy. Several aspects of these theories and their solutions will be discussed
### Black holes and other compact objects in metric-affine Ricci-based theories of gravity

**Inicio:** 00:00h

**Ponente:** Diego Rubiera-Garcia (Institute of Astrophysics, University of Lisbon)

**Lugar:** Alberto Lobo room

**Inicio:** 00:00h

**Ponente:** Diego Rubiera-Garcia (Institute of Astrophysics, University of Lisbon)

**Lugar:** Alberto Lobo room

I will discuss recent progress on the existence of black holes and horizonless compact objects in a class of theories constructed out of contractions of the Ricci tensor with the metric, and formulated on a metric-affine approach, where metric and affine connection are independent degrees of freedom. These theories yield ghost-free second-order field equations and contain just the two standard tensor polarization models of the gravitational field that propagate at the speed of light, thus allowing these theories to survive the slaughter on modified theories of gravity resulting from the beginning of multimessenger astronomy. Several aspects of these theories and their solutions will be discussed
### The ESPRESSO spectrograph and the quest for ExoEarths

**Inicio:** 12:00h

**Ponente:** Jonay I. González Hernández (Instituto de Astrofísica de Canarias (IAC, Tenerife, Canary Islands, Spain))

**Lugar:** Alberto Lobo Seminar Room

**Inicio:** 12:00h

**Ponente:** Jonay I. González Hernández (Instituto de Astrofísica de Canarias (IAC, Tenerife, Canary Islands, Spain))

**Lugar:** Alberto Lobo Seminar Room

ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) is a VLT ultra-stable high resolution spectrograph aimed at detecting Earth-mass exoplanets in the habitable zone of quiet, nearby G to M dwarf stars.

The spectrograph is located in the combined Coudé Lab of the VLT and will be able to operate either using one 8.2m-UT or simultaneously with several of the four UT via four optical Coudé trains. ESPRESSO is expected to achieve a radial velocity precision of 10 cm/s, thus opening the possibility to explore new frontiers in science such as the search for rocky planets, the measurement of the variation of physical constants, or the analysis of the chemical composition of stars in nearby galaxies.

In this talk I will show the main characteristics of the ESPRESSO instrument and the work we have been doing with the aim of finding Earth-like planets.

### Let there be light -- faint galaxies and their pathways of formation

**Inicio:** 12:00h

**Ponente:** Anna Ferré-Mateu (Swinburne University of Technology)

**Lugar:** Sala Alberto Lobos

**Inicio:** 12:00h

**Ponente:** Anna Ferré-Mateu (Swinburne University of Technology)

**Lugar:** Sala Alberto Lobos

Only once in a generation is there the opportunity to reveal the basic properties of a new galaxy type for the first time. With the advent of more sensitive instruments in the current large telescopes, an entirely new universe is being revealed, as it had never been seen before. And it is a challenging one, a low-luminosity universe that is populated by a myriad of new galaxies that are classified into new fancy families: the ultra-compact dwarfs (UCDs), the compact ellipticals (cEs) and the ultra-diffuse galaxies (UDGs).

Despite some attempts to characterize and understand such galaxies, a recurrent topic prevails: what are they really? Are they intrinsic objects, i.e. were they formed as we see them now?; or were they initially other types of galaxies that have later evolved due to external interactions, which shaped them into what we see now? In the case of cEs, we have been lucky enough to catch some of them 'in the act', being stripped by a larger galaxy. However, at the same time, some of them have been found to be completely isolated and with no signs of interaction. In this talk I will discuss the different pathways for cE formation and the expectations from their super massive black holes. I will also show how a similarly detailed study for all the faint families together can provide crucial clues for the galaxy evolution paradigm.
### 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.

15

Marzo 2018

Marzo 2018

I will discuss recent progress on the existence of black holes and horizonless compact objects in a class of theories constructed out of contractions of the Ricci tensor with the metric, and formulated on a metric-affine approach, where metric and affine connection are independent degrees of freedom.…

I will discuss recent progress on the existence of black holes and horizonless compact objects in a class of theories constructed out of contractions of the Ricci tensor with the metric, and formulated on a metric-affine approach, where metric and affine connection are independent degrees of freedom. These theories yield ghost-free second-order field equations and contain just the two standard tensor polarization models of the gravitational field that propagate at the speed of light, thus allowing these theories to survive the slaughter on modified theories of gravity resulting from the beginning of multimessenger astronomy. Several aspects of these theories and their solutions will be discussed

05

Marzo 2018

Marzo 2018

I will discuss recent progress on the existence of black holes and horizonless compact objects in a class of theories constructed out of contractions of the Ricci tensor with the metric, and formulated on a metric-affine approach, where metric and affine connection are independent degrees of freedom.…

I will discuss recent progress on the existence of black holes and horizonless compact objects in a class of theories constructed out of contractions of the Ricci tensor with the metric, and formulated on a metric-affine approach, where metric and affine connection are independent degrees of freedom. These theories yield ghost-free second-order field equations and contain just the two standard tensor polarization models of the gravitational field that propagate at the speed of light, thus allowing these theories to survive the slaughter on modified theories of gravity resulting from the beginning of multimessenger astronomy. Several aspects of these theories and their solutions will be discussed

15

Enero 2018

Enero 2018

ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) is a VLT ultra-stable high resolution spectrograph aimed at detecting Earth-mass exoplanets in the habitable zone of quiet, nearby G to M dwarf stars. The spectrograph is located in the combined Coudé Lab of…

ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) is a VLT ultra-stable high resolution spectrograph aimed at detecting Earth-mass exoplanets in the habitable zone of quiet, nearby G to M dwarf stars.

The spectrograph is located in the combined Coudé Lab of the VLT and will be able to operate either using one 8.2m-UT or simultaneously with several of the four UT via four optical Coudé trains. ESPRESSO is expected to achieve a radial velocity precision of 10 cm/s, thus opening the possibility to explore new frontiers in science such as the search for rocky planets, the measurement of the variation of physical constants, or the analysis of the chemical composition of stars in nearby galaxies.

In this talk I will show the main characteristics of the ESPRESSO instrument and the work we have been doing with the aim of finding Earth-like planets.

21

Diciembre 2017

Diciembre 2017

Only once in a generation is there the opportunity to reveal the basic properties of a new galaxy type for the first time. With the advent of more sensitive instruments in the current large telescopes, an entirely new universe is being revealed, as it had never been seen before. And it is a challenging…

Only once in a generation is there the opportunity to reveal the basic properties of a new galaxy type for the first time. With the advent of more sensitive instruments in the current large telescopes, an entirely new universe is being revealed, as it had never been seen before. And it is a challenging one, a low-luminosity universe that is populated by a myriad of new galaxies that are classified into new fancy families: the ultra-compact dwarfs (UCDs), the compact ellipticals (cEs) and the ultra-diffuse galaxies (UDGs).

Despite some attempts to characterize and understand such galaxies, a recurrent topic prevails: what are they really? Are they intrinsic objects, i.e. were they formed as we see them now?; or were they initially other types of galaxies that have later evolved due to external interactions, which shaped them into what we see now? In the case of cEs, we have been lucky enough to catch some of them 'in the act', being stripped by a larger galaxy. However, at the same time, some of them have been found to be completely isolated and with no signs of interaction. In this talk I will discuss the different pathways for cE formation and the expectations from their super massive black holes. I will also show how a similarly detailed study for all the faint families together can provide crucial clues for the galaxy evolution paradigm.

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.

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