Over the course of the 20 years of Futura, it is interesting to point out some fascinating topics in astrophysics, which still raise many questions. The oldest being the dark matter that has haunted us for decades.
Evaluates the recent hot debates about very prevalent, called UDG (Ultra-diffuse galaxies). They are big galaxies, but their mass Who is this . Its surface density is very low, and theory predicts that it should be dominated by . It is true that some, on the other hand, others interact with more massive galaxies, it is not.
Is it a problem of measurement or interpretation? Or are they still unbalanced, because they are upset with? These galaxies are also tests of alternative theories of dark matter.
Another area in which progress has been rapid in recent years is the field of ). Duncan Lorimer and colleagues published their discovery in 2007, and FRBs remained a mystery for several years because they did not repeat themselves; It was impossible to know which They were responsible for that. In the past decade, repeats have been discovered, and more and more FRBs, some in the Milky Way, have been traced back to , especially things intense, and .or FRB (
Presentation by Professor Françoise Coombes for the 2016-2017 session: “Dark Energy and Models of the Universe”. © College of France
The mysterious and paradoxical accelerating expansion of the universe
The He had a turbulent history. It was discovered in 1929 with measurements From the Vesto Sliver galaxies, the distances obtained by the newly discovered law of the luminosity relationship period , via , in 1909. This first relationship between the distance and velocity of galaxies is the law of proportionality with a constant H It is equal to approximately 10 times the constant known today. Father Lemitri was the first to realize that it wasn’t really a question but who Space saved by Dr’ from The year 1915. Going back in time, the primordial universe is baptized as primitive that becomes With Fred Hoyle in 1949.
This popular constant varied a lot during XXNS century, where the distances of galaxies are unknown. They range between 50 and 100 km/s/Mpc, which has a significant impact on the age of the universe: in addition to H Bigger, younger age of the universe.
So much so that some stars are getting older in the age of the universe!
For nearly 20 years, all the observations (cosmic background withAnd And , SNIa, etc.), on creating a convergence model of the universe, with 30% matter, 70% of , the constant H = 70 km / sec / MPC. However, in recent years, tension has arisen between the value of H. Measured locally (Cepheids and other standard candles) and inferred from LCDM, with the physics of the primordial universe: H.= 73 on one side, 66 km/s/Mpc on the other side.
The area to be explored is still enormous…
For 13.7 billion years, the universe has not stopped evolving. Contrary to what our eyes tell us when we contemplate the sky, what it consists of is far from consistent. Physicists have observations of different eras of the universe and run simulations in which they reshape the universe and its evolution. Dark matter appears to have played a large role from the beginning of the universe until forming the large structures observed today. © CEA Research
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