Chinese and French scientists have revealed that the mass of the Milky Way is lighter than previous measurements

IT House January 13 news, according to the National Astronomical Observatory website, the total mass of the Milky Way is the basic parameter of astrophysics, and is directly related to many important astrophysical problems. Recently, an international team led by Wang Jianling, associate researcher of the National Astronomical Observatory, collaborated with Francois Hammer and Dr. Yang Yanbin of the Paris Observatory to derive the mass distribution of baryonic matter and dark matter in the Milky Way using the latest observation data from the Gaia satellite and combined with a new generation of dynamic modeling methods. They found that the Mass of the Milky Way ranged from 500 to 800 billion solar masses, suggesting that the Milky Way was lighter than previous measurements. This result was recently published in the international journal Royal Monthly.

According to reports, due to the importance of the mass of the Milky Way, scientists have been trying to accurately measure the mass of the Milky Way and its distribution over the past few decades. However, the results of previous studies are limited in many ways. First, the results of the study were uncertain due to the small size of the observational sample data. Second, due to the lack of high-quality 6-dimensional phase space coordinates, it is necessary to use simple hypothetical conditions to derive the mass of the Milky Way, which leads to large systematic errors. Large-scale spectral surveys in recent years and the latest dynamic information released by the Gaia satellite have provided a large amount of high-quality galactic object data. This is the golden age for studying the structure, formation, and evolution of the Milky Way. The first task before astronomers is how to use this high-quality data to study the structure and formation of the Milky Way. Dynamic modeling is one of the main tools for studying the structure of the Milky Way.

An international team composed of Dr. Wang Jianling of the National Astronomical Observatory and francois Hammer and Yang Yanbin, researchers at the Paris Observatory in France, used a new generation of dynamic modeling methods to dynamically model the Milky Way, and derived the mass distribution of baryonic matter and dark matter in the Milky Way. Using the high-precision self-contained information of the Gaia satellite, they calculated kinematic information for the Milky Way's 150 globular clusters. The Markov chain Monte Carlo method (MCMC) is used to combine the rotation curve on the disk with globular cluster dynamic information. They used a dynamical modeling method based on the action distribution function method of the Milky Way, overcoming a large number of assumptions of the predecessors, so as to obtain a more realistic distribution function of globular clusters and the distribution of matter in the Milky Way. They also used N-body numerical simulation techniques to study the possible effects of the Large Magellanic Cloud, which first passed through the Milky Way. And using real cosmological fluid dynamics simulation data, the effects of a large number of substructures that have not been relaxed on the measurement results have been studied.

They found that the total mass of the Milky Way ranges from 5 to 800 billion solar masses, suggesting that our Milky Way is less massive than previously thought. This lightweight Milky Way has implications for numerous astrophysical problems, such as the origin of dwarf galaxies in the Milky Way, the problem of galaxy galaxy lost by cosmology, and so on.

▲ Comparing the milky way rotation curve, the red dotted line is Wang et al. (2022) Measurement of the Milky Way's rotation curve, black and pink dotted lines are the rotation curves contributed by dark matter and heavy matter | Source: National Astronomical Observatory website