Conveners
Tuesday morning
- Antonio López Maroto (UCM)
We are in the middle of a pause. While we ponder the results of the Planck mission and a host of probes of large scale structure, and while we wait for a host of new larhe scale surveys - Euclid, LSST, DESI, to name a few - we can take stock of where we are in our understanding of the late time evolution of the Universe. I will discuss where we are in terms of theory and talk about a few of...
The Cosmological Principle is applied to a 5D Ricci-flat (bulk) manifold. The general solution is given explicitly in the form of a single metric, namely ‘M-metric’, for every sign of the space curvature, both in the 4+1 and the 3+2 case. Friedmann-Robertson-Walker (FRW) metrics are obtained by projecting the ‘mother’ M-metric onto specific 3+1 (brane) hypersurfaces (top-down approach). This...
It has been shown that the longitudinal mode of a massive vector boson can be produced by inflationary fluctuations and account for the dark matter content of the Universe. In this work we examine the possibility of instead producing the transverse mode via the coupling ϕFF̃ between the inflaton and the vector field strength. Such a coupling leads to a tachyonic instability and exponential...
One possible and natural derivation from the collisionless cold dark matter (CDM) standard cosmological framework is the assumption of the existence of interactions between dark matter (DM) and photons or neutrinos. Such interacting DM models would imply a suppression of small-scale structures due to a large collisional damping effect and can help alleviate alleged tensions between standard...
In this talk, we present Cherenkov Telescope Array (CTA) prospects for WIMP dark matter (DM) indirect detection through very-high-energy gamma rays originated from DM annihilations in low-mass Galactic DM subhalos. Given their masses, these are not expected to host gas/stars at all and would thus appear in the sky as unidentified gamma-ray sources (unIDs). By using the latest instrumental...
The Planck Mission from ESA has recently provided the best available full-sky intensity and polarization CMB data, covering a range of frequencies from 30 to 857 GHz. In this talk I will give an overview of the main Planck legacy results, which currently provide our strongest constraints on the parameters of the standard cosmological model. I will also briefly review the current and future...
We propose a novel scenario for the detection of radio signals from axionic halo dark matter. Axions or axion-like particles produce radio waves via spontaneous decay into two photons. In addition, stimulated emission by a background containing photons of identical wavelength enhances the rate of photon emission by axionic decay. A photon background generated by a bright radio source should...
The PAU Survey (PAUS) is an imaging survey using a 40 narrow-band filter camera, named PAUCam. Images obtained with the PAUCam suffer from scattered light: an optical effect where light appears where it is not intended to be. Scattered light is not a random effect, it can be predicted and corrected for. Nevertheless, currently, around 8% of the PAUS flux measurements are flagged as scattered...
Cosmic voids gravitationally lens the cosmic microwave background (CMB) radiation, resulting in a distinct imprint on degree scales. We aimed to probe the consistency of simulated ΛCDM estimates and observed imprints of voids identified in the first year data set of the Dark Energy Survey (DES Y1). In particular, we intended to explore other aspects of the previously reported excess integrated...
Total density of the Universe is very close to the critical density; that is, the matter-energy content is exactly that required in the Universe to be flat. This strange coincidence ('flatness problem') has not yet been explained, as well as the nature of dark energy, which compensates the gavitational force caused by the matter. To explain the origin of the dark energy, this works uses a...
Using the formalism of quantum field theory in curved spacetimes, we study semiclassical effects in geometries which get close to the formation of an event horizon. These geometries are such that they imprint special features on the quantum vacuum of the fields. Specifically, we will present a series of asymptotically flat, spherically symmetric spacetimes which get close to the formation of a...
In this talk I will make a sort review on alternative theories of gravity with torsion along with a brief statement for their motivation. Then, I will focus my speech on Lagrangian densities quadratic in the curvature and torsion tensors, as they are known to produce a dynamic torsion field. By assuming that General Relativity should be recovered when the torsion vanishes and investigating the...
Regardless of the precise nature of dark matter (DM), its distribution in the central regions of galaxies remains poorly constrained at present. In particular, DM halos may be significantly affected by the presence of central supermassive black holes, leading to the possible formation of high density spikes. Two objects are of particular interest in this context: Sgr A* at the center of the...
