Cosmic strings: topological defects of space-time

At the heart of contemporary cosmology research are the cosmic strings, these hypothetical narrow-dimensional objects capable of revealing previously unsuspected aspects of the primitive universe. Appearing in the first moments following the Big Bang, they represent topological defects in the very fabric of spacetime, creating a kind of deformed scar on a cosmic scale. Their … Read more

Galactic halos and their dark matter

In the ever-expanding universe, galactic halos stand out as fascinating structures enveloping our familiar galaxies. These vast spherical regions are primarily composed of dark matter, an invisible substance that cannot be directly detected but whose gravitational influence is crucial for understanding modern cosmology. The study of galactic halos allows us to decipher the large-scale organization … Read more

Galactic hydrogen filaments

Galactic hydrogen filaments represent one of the fundamental components of cosmic structure, drawing a complex network that shapes the visible universe. These gigantic chains of baryonic matter, primarily composed of neutral hydrogen clouds, play a crucial role in the intergalactic medium by orchestrating galaxy formation and the evolution of galaxy clusters. Thanks to recent advances … Read more

Cosmic inflation: the blistering expansion of the early universe

Cosmic inflation unveils a fascinating chapter in the history of the primitive universe, marking a period of frenzied expansion that precedes the formation of cosmic structures such as galaxies and star clusters. This theory, initially formulated in 1980 by physicist Alan Guth, offers a compelling explanation for several enigmas of the standard cosmological model, including … Read more

Interstellar bubbles and their origin

In brief: Between diffuse matter and stellar explosions, interstellar bubbles trace the dynamics of a cosmos in perpetual change. These hollow nebulae, sometimes visible in X-rays or in the radio domain, emerge as witnesses of the winds projected by massive stars or debris from ancient supernovae. The complex interaction between these stellar winds and the … Read more

The primordial nucleosynthesis: formation of the first chemical elements

At the heart of the first minutes of the Universe, a decisive phenomenon took place, marking the origin of matter as we know it today: primordial nucleosynthesis. This brief but intense period allowed the initial formation of light atomic nuclei, notably hydrogen, helium, and lithium. The story of this cosmic alchemy dives into an expanding … Read more

The cosmic microwave background: the echo of the Big Bang in the universe

The cosmic microwave background (CMB) presents itself as an almost perfect and captivating imprint of what the Universe was like in its early moments, a true echo of the Big Bang enveloping the cosmos. This incessant radiation, invisible to the naked eye, has traversed nearly 14 billion years of expansion to provide us with crucial … Read more

Dark energy: why is the expansion of the universe accelerating?

The enigma of {{strong|dark energy}} has fascinated astrophysicists for several decades. First observed with the discovery of a {{strong|cosmic acceleration}} in the expansion of {{strong|the universe}} at the end of the 20th century, this mysterious force challenges the classical knowledge of modern {{strong|cosmology}}. Constituting about 70% of the total content of the universe, as revealed … Read more

Dark matter: understanding 85% of the invisible universe

Since the dawn of modern cosmology, dark matter has intrigued researchers with its fundamental role in the structuring of the universe while remaining practically elusive. This mysterious substance, which accounts for about 85% of the total mass of the invisible universe, profoundly influences the movement of galaxies and the evolution of large cosmic structures. Yet, … Read more

The alignment of galactic spins

In the vast universe, the rotation of galaxies continues to fascinate astronomers who seek to understand the mechanisms behind this fundamental movement. The orientation of galaxies, often perceived as random, actually reveals a more subtle organization. The alignment of galactic spins – the preferred direction in which galaxies rotate – has become a key area … Read more