Conveners
Non Standard Cosmological Probes: Block 1
- Michele Moresco (University of Bologna)
- Lorenzo Amati (INAF - OAS Bologna)
Non Standard Cosmological Probes: Block 2
- Lorenzo Amati (INAF - OAS Bologna)
- Michele Moresco (University of Bologna)
Description
Cosmological studies of the last twenty years have mainly focused on the use of CMB, SNe, BAO, WL. While the combination of these methods has proven extremely powerful in constraining the values of cosmological parameters, some recent Ho measurements, obtained with “local” indicators such as Cepheids and type Ia SNe, show an existing tension with the prediction from Planck CMB observations under ΛCDM. This fact requires new efforts to study different approaches and methods for studying the expansion of the Universe and the evolution of dark energy. This session presents an overview of the alternative cosmological probes that have been developed in recent years, such as: GRB, QSO, GW, delayed cosmography, cosmic chronometers. We will discuss how these probes can be exploited to extract independent cosmological constraints and explore the synergies between these and standard cosmological methods. One of the goals of the session is to foster discussion of how these probes can provide, in perspective, a fundamental contribution to our understanding of the Universe.
I will describe how radio instruments like MeerKAT and the SKA can kick off an exciting new era in cosmology, by using the intensity mapping technique. I will emphasise the importance of synergies with optical galaxy surveys like Euclid and LSST. I will also talk about pathfinder data analysis work, in particular the recent GBT-eBOSS detections, and the analysis of Science Verification data...
I will present the latest results on our analysis of the non-linear X-ray to ultraviolet luminosity relation in a sample of optically selected quasars from SDSS, cross-matched with the most recent XMM-Newton and Chandra catalogues. I will show that this correlation is very tight, implying that the observed relation is the manifestation of an ubiquitous (but still unknown) physical mechanism,...
Gamma-ray bursts are among the most luminous transients in the Universe, a characteristic that permits us to observe them at very high redshifts. For this reason, many efforts have been made to identify a method to use GRBs as cosmological distance indicators through the use of luminosity correlations between their high-energy observable quantities. In this talk, I will review some of the most...
Explaining the accelerated expansion of the Universe is one of the most challenging topic in physics today. Cosmography provides information about the evolution of the universe, assuming only that the space time geometry is described by the Friedman-Lemaitre-Robertson-Walker metric.Cosmography traditionally involves Taylor expansions of the observable quantities, and the results of this...
The surface brightness fluctuations (SBF) method is one of the most robust extragalactic distance indicators: with an accuracy comparable to SNe Ia and Cepheids (∼5% per galaxy) without the limitations of the serendipitousness intrinsic of SNe, or the long observing campaigns needed for Cepheids. Moreover, it is used in a wide range of distances: from very local, up to values relevant for...
In this talk, I will present a novel approach to obtain constraints on the expansion rate of the Universe based on the differential age evolution of "cosmic chronometers". The strength of this method is that it allows a direct measurement of the Hubble parameter $H(z)$ without relying on any cosmological assumptions, providing an ideal framework to test cosmological models.
I will review the...
Massive and passive galaxies can be used as cosmic chronometers to study the expansion history of the Universe. In particular, by following their differential age evolution over different cosmic epochs it is possible to obtain direct measurements of the Hubble parameter, $H(z)$. However, robust age estimates require deep spectroscopy to break internal degeneracies between stellar population...
By observing the gravitational waves from the coalescence of a compact binary merger, it is possible to directly infer the luminosity distance to the source. This measurement does not use a distance ladder; the calibration is provided directly from the theory of general relativity. We discuss the present state of the field of GW cosmology, and its future promise.
Modern surveys provide access to high-quality measurements on large areas of the sky, sampling the galaxy distribution in detail also in the emptiest regions, voids. Void cosmology is becoming an increasingly active sector of galaxy clustering analysis: by measuring void properties, such as density profiles or void number counts, it is possible to constrain cosmological parameters. Cosmic...
In a non-empty universe, the Hubble expansion is dynamic. Under the current cosmological paradigm, the expansion decelerated when the universe was matter-dominated but is now accelerating due to dark energy. The dynamic expansion can be observed directly as a secular cosmological redshift drift, and this measurement does not rely on the cosmological distance ladder or any cosmological model....
The arrival time delays of multiply imaged strong gravitationally lensed sources provides a one-step cosmological distance measurement. The methodology, known as time-delay cosmography, rose to prominence to provide precise measurements of the Hubble constant, independent of the local distance ladder and the cosmic microwave background. I introduce the methodology and key ingredients, as well...
Velocity field provides an alternative avenue to constrain cosmological information, and one of the commonly used statistics is the mean radial pairwise velocity. In this talk, we consider the three-point mean relative velocity (i.e. the mean relative velocities between pairs in a triplet), and show that it is a novel probe of neutrino mass estimation. We explore the full cosmological...
The spatial distribution of matter depicts a complex pattern commonly referred to as the 'cosmic web' in which massive nodes are linked together by elongated filaments found at the intersection of thin mildly-dense walls, themselves surrounding large and empty voids.
The intrinsically different gravitational dynamics history that each environment experience leaves an imprint on the present...
The shape of redshift distribution for uniform sources set in our Metagalaxy defined by cosmological parameters and properties of space is Euclidean at small redshifts and de-Sitter at z>0.7. Firstly the parameters of our Metagalaxy Ω and Λ were determine due sample of Ia supernovae from the Supernova Cosmology Project analysis in 1998. Now several thousand supernovae characteristics analyzed...
The redshift drift (also known as the Sandage Test) is a model-independent probe of fundamental cosmology, enabling us to watch the universe expand in real time, and thereby to confirm (or not) the recent acceleration of the universe without any model-dependent assumptions. On the other hand, by choosing a fiducial model one can also use it to constrain the model parameters, thereby providing...
