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
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
Since the discovery of pulsars, these rapidly rotating neutron stars that emit periodic radio impulses, humanity has found in these celestial objects one of the most fascinating astrophysical phenomena. Among them, millisecond pulsars stand out for their unique ability to combine extreme rapid rotation and unparalleled temporal precision, rivaling even the most sophisticated atomic clocks … Read more
The Drake equation, formulated in 1961 by astronomer Frank Drake, remains an essential pillar in the field of astrophysics and astrobiology. This mathematical tool aims to quantify the number of potentially communicative advanced civilizations within our galaxy. From its inception, this sophisticated relationship has paved the way for a rigorous scientific approach to the search … Read more
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
In the vast field of cosmology, topological defects emerge as silent witnesses of the first fractions of seconds of the primordial universe. These unique structures, often stable, would have formed during cosmic phase transitions, crucial moments when the universe saw its fundamental symmetries break. These breaks left behind singular configurations of matter and energy, which, … Read more
The cosmic microwave background, often referred to as fossil radiation, is an extraordinary witness of the primordial universe. Originating from the time when the first atoms could form, this radiation reveals the state of the Universe approximately 380,000 years after the Big Bang. However, far from being perfectly uniform, it presents small temperature variations known … Read more
Since the end of the 1990s, contemporary astronomy has revealed an unsuspected facet of our cosmos: a mysterious force, dubbed dark energy, which represents about 70% of the total energy density of the Universe and is responsible for the acceleration of its expansion. This phenomenon is intimately linked to the cosmological constant, a notion introduced … Read more
The cosmological horizon problem embodies one of the major challenges in modern cosmology, questioning the very foundations of our understanding of the observable universe. This conundrum raises a fascinating question: how can extremely distant regions of the universe, seemingly without any causal contact, exhibit such surprising homogeneity, particularly seen in the cosmic microwave background radiation? … Read more
Baryonic acoustic oscillations (BAO) represent a fundamental phenomenon in cosmology, marking a crucial sequence in the history of the Universe. These primordial sound waves, which occurred in the hot plasma composed of baryons and photons, have left indelible traces visible in the large-scale structure of the Universe. By studying these oscillations, astrophysicists gain access to … Read more