СЕМІНАР НДІ астрономії ХНУ 8 червня 2021 р.

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Published on Monday, 07 June 2021 Written by Юлія Антоненко

astroСЕМІНАР (online) 

НДІ астрономії ХНУ 8 червня 2021 р., вівторок15:15

Kseniia Sysoliatina (Astronomisches Rechen-Institut (ARI))
"Just-Jahrei model of the Milky Way disk: basics, predictions, and calibration against Gaia data" 
 
Abstract: The most advanced Galactic models up to date can be produced by numerical simulations: N-body modeling or more realistic (magneto)hydrodynamic simulations, where not only mass particles are considered, but also stellar evolution and feedback processes are taken into account. Also, there is semi-analytic modeling: in this case, the Milky Way (MW) evolution processes are described by analytic functions. Then, fairly often, the dynamics of the stellar populations can be described with the Poisson and collisionless Boltzmann equations. This allows building realistic MW models relatively quickly and, thus, testing many different models against the observational data.
The semi-analytic Just-Jahrei (JJ) model describes the axisymmetric Galactic disk in a steady state which consists of the exponential thin, thick, and gaseous disks, as well as stellar and dark matter halo. The thin disk evolution is described by the analytic initial mass function (IMF), star formation rate (SFR), age-velocity dispersion relation (AVR), and age-metallicity relation (AMR). At each Galactocentric distance R, a self-consistent pair of the vertical density profile and gravitation potential is calculated by iterative solving of the Poisson-Boltzmann equation. Combined with a stellar library, the JJ model can be used to analyze different stellar populations in terms of vertical velocity or metallicity distributions, color-magnitude diagrams, spatial number densities, etc.
Recently, we compared the JJ model to the local Gaia data. Working within a Bayesian approach, we sampled the posterior probability distribution in a multidimensional parameter space using the MCMC method and self-consistently constrained 22 parameters of the JJ model, such that it now reproduces the local star counts with a 5-% accuracy. We found that Gaia data imply the presence of two peaks on top of the SFR declining continuum, 0.5 Gyr and 3 Gyr ago, which may point to the episodes of gas infall. 
 
Обговорення на ФБ:
 
Сторінка семінару:
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Семінар буде проходити в Zoom:

Meeting ID: 997 4811 5406
Passcode: 114313
 
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Паралельно з Zoom буде проходити трансляція у Фейсбук:

Початок трансляції: 2021.06.08 15:15 (за Київським часом)
Запитання можна буде ставити у коментарях до трансляцій або голосом в Zoom.

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