Akrami, Yashar Sasaki, Misao Solomon, Adam R. Vardanyan, Valeri

We argue that dark energy with multiple fields is theoretically well-motivated and predicts distinct observational signatures, in particular when cosmic acceleration takes place along a trajectory that is highly non-geodesic in field space. Such models provide novel physics compared to $\Lambda$CDM and quintessence by allowing cosmic acceleration o...

Abellan, Guillermo F. Murgia, Riccardo Poulin, Vivian Lavalle, Julien

Recent weak lensing surveys have revealed that the direct measurement of the parameter combination $S_8\equiv\sigma_8(\Omega_m/0.3)^{0.5}$ -- measuring the amplitude of matter fluctuations on 8 $h^{-1}$Mpc scales -- is $\sim3\sigma$ discrepant with the value reconstructed from cosmic microwave background (CMB) data assuming the $\Lambda$CDM model. ...

Di Valentino, Eleonora Anchordoqui, Luis A. Akarsu, Ozgur Ali-Haimoud, Yacine Amendola, Luca Arendse, Nikki Asgari, Marika Ballardini, Mario Battistelli, Elia Benetti, Micol
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The standard $\Lambda$ Cold Dark Matter cosmological model provides a wonderful fit to current cosmological data, but a few tensions and anomalies became statistically significant with the latest data analyses. While these anomalies could be due to the presence of systematic errors in the experiments, they could also indicate the need for new physi...

Elbistan, M. Zhang, P.M. Gibbons, G.W. Horvathy, P.A.

The Lukash metric is a homogeneous gravitational wave which approximates at late times the behaviour of a generic class of spatially homogenous cosmological models with monotonically decreasing energy density. Following pioneering work of Siklos, we provide a self-contained account of the geometry and global structure of the spacetime. The latter c...

Martin, Jerome Vennin, Vincent

The Continuous Spontaneous Localisation (CSL) model solves the measurement problem of standard quantum mechanics, by coupling the mass density of a quantum system to a white-noise field. Since the mass density is not uniquely defined in general relativity, this model is ambiguous when applied to cosmology. We however show that most natural choices ...

Martinelli, M. Martins, C.J.A.P. Nesseris, S. Sapone, D. Tutusaus, I. Avgoustidis, A. Camera, S. Carbone, C. Casas, S. Ilić, S.
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In metric theories of gravity with photon number conservation, the luminosity and angular diameter distances are related via the Etherington relation, also known as the distance-duality relation (DDR). A violation of this relation would rule out the standard cosmological paradigm and point at the presence of new physics. We quantify the ability of ...

Mastrogiovanni, S. Steer, D. Barsuglia, M.

The direct detection of gravitational waves by the LIGO-Virgo collaboration has opened a new window with which to measure cosmological parameters such as the Hubble constant $H_0$, and also probe general relativity on large scales. In this paper we present a new phenomenological approach, together with its inferencial implementation, for measuring ...

Han, Dongwon Sehgal, Neelima MacInnis, Amanda van Engelen, Alexander Sherwin, Blake D. Madhavacheril, Mathew S. Aiola, Simone Battaglia, Nicholas Beall, James A. Becker, Daniel T.
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We present LCDM cosmological parameter constraints obtained from delensed microwave background power spectra. Lensing maps from a subset of DR4 data from the Atacama Cosmology Telescope (ACT) are used to undo the lensing effect in ACT spectra observed at 150 and 98 GHz. At 150 GHz, we remove the lensing distortion with an effective efficiency of 30...

Parimbelli, G. Anselmi, S. Viel, M. Carbone, C. Villaescusa-Navarro, F. Corasaniti, P.S. Rasera, Y. Sheth, R. Starkman, G.D. Zehavi, I.
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The linear point (LP), defined as the mid-point between the dip and the peak of the two-point clustering correlation function (TPCF), has been shown to be an excellent standard ruler for cosmology. In fact, it is nearly redshift-independent, being weakly sensitive to non-linearities, scale-dependent halo bias and redshift-space distortions. So far,...

Arbey, A. Coupechoux, J.-F

Scalar fields appear in many cosmological models, in particular in order to provide explanations for dark energy and inflation, but also to emulate dark matter. In this paper, we show that it is possible for a scalar field to replace simultaneously dark matter, dark energy and inflation by assuming the existence of a non-minimal coupling to gravity...