Gauge symmetries are known to be respected by gravity because gauge charges carry ๏ฌux lines, but global charges do not carry ๏ฌux lines and are not conserved by gravitational interaction. For discrete symmetries, they are spontaneously broken in the Universe, forming domain walls. Since the realization of discrete symmetries in the Universe must involve the vacuum expectation values of Higgs...
Abstract content
We consider models of chaotic inflation driven by the real parts
of a conjugate pair of Higgs superfields involved in the
spontaneous breaking of a grand unification symmetry at a scale
assuming its Supersymmetric value. Employing Kaehler potentials
with a prominent shift-symmetric part proportional to c- and a
tiny violation, proportional to c+, included in a logarithm...
We carefully study the implications of adiabaticity for the behavior of
cosmological perturbations. There are essentially three similar but
different definitions of non-adiabaticity: one is appropriate for
a thermodynamic fluid $\delta P_{nad}$, another is for a general matter field
$\delta P_{c,nad}$, and the last one is valid only on superhorizon scales.
The first two definitions coincide if...
We analyze two models in which primordial inflation has non-standard features. In the first model we study the evolution of a system in which the inflaton is slowed down by dissipation of energy into gauge bosons instead of the usual Hubble friction: in particular we study the conditions of the onset of such a scenario from a static field configuration and we briefly mention some difficulties...
The low-energy dynamics of a generic self-gravitating media can be studied by using effective field theory in terms four derivatively coupled scalar fields. Imposing SO(3) internal spatial invariance, the theory describes fluids, superfluids, solid and supersolids. Dynamical and thermodynamical properties of the medium are dictated by internal symmetries of the effective theory. From the...
We show that the dimension of spacetime becomes complex-valued when its short-scale geometry is invariant under a discrete scaling symmetry. This characteristic can arise either in quantum gravities based on combinatorial or multifractal structures or as the partial breaking of continuous dilation symmetry in any conformal-invariant theory. With its infinite scale hierarchy, discrete scale...
In an accelerating universe a maximum radius exists above which a shell of test particles cannot collapse and disperses due to the cosmic expansion. Observations of this turnaround radius for large structures could constrain the
effective equation of state of dark energy. We use the Hawking quasilocal mass to make the concept of turnaround radius well defined in general relativity and
then we...
We revisit the decoupling effects associated with heavy particles in the renormalization group running of the vacuum energy in a mass-dependent renormalization scheme. We find the running of the vacuum energy stemming from the Higgs condensate in the entire energy range and show that it behaves as expected from the simple dimensional arguments meaning that it exhibits the quadratic sensitivity...
Clusters of galaxies are unique cosmological probes sensitive to the primordial density fluctuations, and the expansion history and energy content of the Universe. The thermal Sunyaev-Zeldovich (tSZ) effect is an observable of choice for cluster cosmology due tothe low scatter in the relationship between SZ flux and cluster mass, and the construction of large tSZ selected cluster catalogs by...
In this presentation I will talk about QUBIC, an experiment that takes up the challenge posed by the detection of primordial gravitational waves with a novel approach. Detecting the signature left by primordial gravity waves in the Cosmic Microwave Background (CMB) entails measuring a tiny polarized component of the CMB, the so-called B-modes, that is literally buried in polarized...
As the Planck mission is delivering its ultimate results, it has become clear that much is still to be learnt from additional observations of the Cosmic Microwave background. In the light of current results and remaining questions, I will discuss the scientific case of some of the main future CMB projects, their complementarity, and how to address the challenges of measurement accuracy and of...
I will present an overview of the final results from the SDSS-III BOSS analysis (DR12). Using the galaxy power spectrum and correlation function, BOSS was able to measure the Baryon Acoustic Oscillations scale in two independent redshift bins to 1% precision. Such constraints allow to map out the expansion history of the Universe and represent one of the most important cosmological tools at...
The Baryon Oscillation Spectroscopic Survey (BOSS) of SDSS-III has ushered in a new era for high-redshift quasar surveys studying the large-scale structure of the Universe through intervening absorption by the intergalactic gas. The unprecedented number of quasar absorption spectra provided by BOSS allows us to measure the expansion rate and geometry of the Universe at redshift z>2 using...
Type Ia supernovae (SNe Ia) have proved to be a successful probe of dark energy thanks to their property of standardizable candle allowing us to construct a supernova Hubble diagram with very low scatter through a two-parameter empirical light-curve correction. However, 0.15 magnitude intrinsic luminosity variation remains once corrections are applied, leaving plenty of room for a third...
Gravitational lensing represents a unique tool to study the dark Universe. In the weak lensing regime small distortions in the images of galaxies caused by the large-scale structure can be detected over the whole sky. Measuring these coherent distortions yields cosmological insights complementary to other probes like the cosmic microwave background (CMB). Ongoing wide-field imaging surveys...
The Dark Energy Survey (DES) is a large galaxy survey designed to address the fundamental question of the accelerating expansion of the universe and uncover the nature of the dark energy. It started the data taking in 2013, providing high quality imaging for 1/8 of the sky. The talk will present the current status of the project and the most recent results, mainly based on data from the first...
The Esa satellite Euclid will launch in 2020. It will observe 15000deg2 of the darkest sky with his visible imager and his near-IR photometer and spectrograph.
The core science goal of the mission is to measure the evolution of the expansion of the universe up to redshift 2 in order to characterise deviations from the concordance LambdaCDM model, determine the evolution properties of dark...
The Large Synoptic Survey Telescope (LSST) is an automated ground-based 8.4m optical telescope, whose first observations are expected in 2023. The aim of this new instrument is to conduct a ten year wide and deep imaging survey of 18,000 square degrees of the sky in six broad optical bands, with a deep stack reaching magnitude $r=27.5$. The LSST design is driven by four science themes: dark...
This talk will present the status of the Advanced LIGO and Advanced Virgo detectors, a year after the first detections of gravitational waves emitted by two binary black hole coalescences. After a 10-month break due to upgrades, maintenance and commissioning, the Advanced LIGO detectors started their second ?Observation Run? (O2) on November 30th 2016. This data taking period is expected to...
The detection of gravitational waves from the merger of binary black holes during the first Advanced LIGO science runs has opened up a new field of astronomy, and a new window on the universe. During these runs, searches for different types of compact binaries are conducted. In this talk, I will review the detected black hole mergers, and discuss the implications of the non-detection of other...
The observations of the presumed binary black hole coalescences GW150914 and GW151226 during the first observing run of Advanced LIGO have allowed us to probe the genuinely strong-field dynamics of Einstein's general theory of relativity (GR) for the first time. We give a brief overview of the tests carried out on the detected signals, which showed consistency with GR within the measurement...
Gravitational-wave astronomy has made a tremendous stride forward with detections during the first observing run of the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO). The signals have been identified as originating from the merger of black holes, whose parameters it was possible to infer. This discovery has profound implications. Gravitational waves provide information on...
Transient gravitational wave emission can originate by phenomena associated with neutron stars (NSs) oscillations modes, such as hyperflares from galactic magnetars and binary coalescence. Potential signals related to these events are generally not well-modeled, requiring robust, morphology-independent analysis techniques. In particular, the coalescence of binary neutron stars (BNS) is a...
The gravitational wave era has started with the detections of gravitational waves originated from the coalescences of black holes. This gives new challenges and interests to the multi-messenger approach, which aims to reach the extraordinary result of identifying the counterparts. In this talk, we review the gravitational wave low-latency algorithms used by the LIGO-Virgo collaboration. Those...
A stochastic background of gravitational waves can be described as a superposition of several uncorrelated contributions. It can be of both cosmological and astrophysical origin. In the first case, it can constitute potentially a unique probe of the primordial universe. In the second, it can give precious information on stellar populations. After discussing how this kind of signal can be...
Continuous gravitational waves emitted by spinning neutron stars, isolated or in binary systems, are among the main targets of LIGO and Virgo interferometric detectors. No continuous wave has been detected so far, but significant upper limits, providing interesting constraints on the characteristics and demography of the potential sources, have been obtained. In this talk I will review the...
Detections of stellar mass binary black holes (BBHs) system in the first observing run of LIGO interferometers has started an exciting new era of black hole astrophysics.
Understanding the possible formation channels of the population of BBH will be important to understand the environment in which such systems are formed. Hence, the recent detections prove that BBHs exists in nature and merge...
