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Dark energy

The dominant and most mysterious ingredient of the current standard model, is, without doubt, the so-called dark energy, that contributes about 75% of the mass/energy density of the Universe, and causes the current accelerating expansion. The most direct evidence for this acceleration comes from the observation of "standard candles" at cosmological distances, or rather objects whose intrinsic luminosities can be calibrated a priori, so that their distance can be measured via their apparent luminosity. The so-called type Ia supernovae have been used in this way, and at the end of the '90s allowed the acceleration to be detected for the first time. Current and future research will concentrate on identifying a time dependence on the so-called "equation of state" of dark energy, to demonstrate whether dark energy is simply Einstein's cosmological constant, or if it is connected to a primordial energy field also related to the formation of elementary particles. To this end, various projects either underway or proposed for the future, are dedicated to systematic searches for type Ia supernovae, both from the ground and space. These will surely greatly increase the volume of data on distant SNe, shedding new light on the nature of cosmic acceleration. The search for and the calibration of new standard candles (such as "core-collapse" SNe and gamma-ray bursts) are also areas of research receiving growing attention.


Other experiments plan to cover large areas of the sky with high quality images (and so in general observed from space) to measure so-called weak lensing. This distortion, introduced in the images of "background" galaxies by the mass distribution along the path that the photons travel to reach us, depends on the gravitational growth of fluctuations, and ultimately on the cosmological parameters. The final goal of these surveys is make maps of the "shear", as the weak lensing deflection is called, in various redshift intervals and reproduce the tomographic distribution of cosmic structure at successive epochs. These "tomographic plates" directly measure the expansion and structure growth history of the Universe that depend directly on the presence of dark energy.

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Apr 25, 2022

AN ARTIFICIAL EYE FOR BILLIONS OF GALAXIES SAMPLES An international group of scientists, including researchers from the Italian National Institute for Astrophysics, has used artificial intelligence (AI) to measure the size of galaxies as far away as about seven billion light-years from Earth

The NEOROCKS project: online the newsletter first issue

Mar 25, 2022

The NEOROCKS project: online the newsletter first issue NEOROCKS (Near-Earth Object Rapid Observation, Characterization and Key Simulations) is an European project financed by the Horizon 2020 UE program. The first issue of the project newsletter is an online magazine to report about news in the NEO field

First light for SiFAP4XP

Mar 08, 2022

First light for SiFAP4XP SiFAP4XP is a new fast photometer with polarimetric capabilities at the TNG Telescope. The project was triggered by the challenging goal to observe in the optical domain the same targets of the IXPE satellite, the first to be specifically dedicated to X-ray polarimetric observations