Cosmologie

Transforming gas-rich low-mass disky galaxies into ultra-diffuse galaxies by ram pressure

Faint extended elliptically shaped ultra-diffuse galaxies and slightly brighter and more compact dwarf elliptical and lenticular stellar systems are common in galaxy clusters. Their poorly constrained evolutionary paths can be studied by identifying young ultra-diffuse galaxy and dwarf elliptical analogues populated with bright, massive stars. Using data mining we identified 11 such low-mass (2 × 10^8 M⊙ < M* < 2 × 10^9 M⊙) galaxies with large half-light radii (2.0 kpc < re < 5 kpc) and recently quenched star formation in the Coma and Abell 2147 galaxy clusters.

Results and open questions on two coasting cosmological models

The ΛCDM Model accurately reproduces most cosmological observations, including primordial nucleosynthesis, the cosmic microwave background radiation, and baryonic acoustic oscillations. However, standard baryonic matter constitutes only 5% of the total content of the ΛCDM universe, while the dominant components – cold dark matter (≈25%) and dark energy (≈70%) – are yet unobserved.

The European Low Frequency Survey: observing the radio sky to understand the beginning of the Universe

Nowadays the leading contender to understand the initial conditions of the Big Bang is inflation, which predicts the existence of a primordial background of gravitational waves that must have left its imprint in the CMB polarization: the so-called ​ B-modes. The main difficulty in measuring the ​ B-modes comes not just from its sheer faintness but from the fact that many other objects in the universe also emit polarized microwaves.

The power of probe combination : cosmology with LSS and CMB data

Through weak lensing and galaxy clustering measurements, the next generation of large-scale surveys (Euclid, LSST, ...) will provide unprecedented observations and constraints on the late Universe, and thus shed light on dark matter and dark energy. On the other hand, high-quality CMB observations (current and planned) can -- and already do -- put tight constraints on the early Universe and its content.

PPCM meeting #4 at APC

Dear cosmologists of the Parisian area and beyond,

This is a reminder that our next PPCM meeting will be held next week, on the 3rd of March at APC.

A program is available on PPCM's website and on the Indico webpage of the event where you are kindly asked to register. It is also summarised at the end of this email.

Best regards,

Yashar Akrami (ENS), Julien Grain (IAS), Sébastien Renaux-Petel (IAP),  Vincent Vennin (APC), Filippo Vernizzi (IPhT - CEA).

Cosmology with peculiar velocities

The Universe is not homogenous. Since the early times, its structures have grown and moved under the laws of gravity. By measuring these motions today we are able to trace the spatial distribution of dark matter and accurately map the Universe. The comparison of the recovered large scale structures with the predictions of the concordance model of cosmology is then a powerful test of the laws of expansion and gravity. 

Pages

S'abonner à RSS - Cosmologie