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Formarea Galaxiilor de tip Caleea Lactee (Simulari cosmologice)

Formarea Galaxiilor de tip Caleea Lactee (Simulari cosmologice). Workshop Exploratoriu ‘Astronomia Romaneasca’, Sep 22-23, 2010. Andreea Font Institute of Astronomy, University of Cambridge. Calea Lactee in context cosmologic (Lambda CDM) - formare hierarhica.

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Formarea Galaxiilor de tip Caleea Lactee (Simulari cosmologice)

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  1. Formarea Galaxiilor de tip Caleea Lactee (Simulari cosmologice) Workshop Exploratoriu ‘Astronomia Romaneasca’, Sep 22-23, 2010 • Andreea Font • Institute of Astronomy, University of Cambridge

  2. Calea Lactee in context cosmologic (Lambda CDM) - formare hierarhica In paradigma cosmologiei de tip Lambda CDM galaxiile se alcatuiesc hierarhic (structuri mici -> mari). Galaxia noastra s-a alcatuit prin asimilarea multor galaxii mici (“pitice”). Urmele acestor procese de asimilare ramin in constitutia actuala de stele din galaxia noastra -> “arheologie” stelara 1. Reconstruirea procesului de asamblare a diverselor componente ale galaxiei noastre: halo, bulge, disk, satellites (Culegere de date obs). 2. Comparatie cu predictiile modelului LambdaCDM (Simulari pe calculator). 3. (In)Validare a modelului cosmologic

  3. A New Era of Galaxy Surveys • RAVE(The Radial Velocity Experiment): • all sky survey to measure radial velocities • and spectra of about 50 million stars in the Galaxy. • SEGUE2(Sloan Extension for Galaxy Underpinnings and Exploration): SDSS extension; survey to produce high resolution spectra for about 240,000 stars in the Galaxy. • GAIA(Global Astrometric Interferometer for Astrophysics): will measure positions, line of sight velocities and proper motions of about • 1 billion stars in the Galaxy; also spectroscopy. • Other: LAMOST, PanStarrs, LSST, SkyMapper, HERMES, etc.

  4. Metode computationale I. Metode Semi-analitice: - combina simulari N-body (dinamica) cu tratament semi-analitic a proceselor fizice (atomi, molecule, radiatie)

  5. Metode computationale I. Metode Semi-analitice: - combina simulari N-body (dinamica) cu tratament semi-analitic a proceselor fizice (atomi, molecule, radiatie) - Componentele stelare se modeleaza separat in interiorul fiecarui halou de materie intunecata

  6. Virgo Consortium for Cosmological Simulations • UK, Germany, Canada, Netherlanda, USA, Japan • Resources: • -“Cosmology Machine” (Durham) 792 opteron cpus +500 ultra-sparcIII processors • IBM Regatta System (Garching) • 816 power-4 processors • Blue Gene Supercomputer (Groningen) • Darwin supercomputer (Cambridge) • The Aquarius Project • - State-of-the-art in Milky Way simulations • 1.5 billion dark matter particles • mass/particle 10^3 Msol

  7. Ratii ale elementelor chimice in stele How do we make this... .. from this? stellar halo [α/Fe] dSph dIrr satellite stars data from Venn 04 Venn et a. (2004) [Fe/H]

  8. Halo is alpha-enhanced because it is formed from earlier accretion events. [α/Fe] Surviving satellite galaxies are accreted later data from Venn 04 [Fe/H] Font et al 2006

  9. Recent, high lum streams are more metal-rich. Explains why most observed streams are metal-rich. We’re currently detecting the tip of the iceberg…

  10. Metode ComputationaleII. Simulari hidro-dinamice (SPH) GIMIC(Galaxies Intergalactic Medium Interaction Calculation) Virgo Consortium for Computational Cosmology Gadget-3 : updated prescriptions of radiative cooling, reionization, star formation, feedback from Type Ia/II sNe, chemical enrichment from Sne and AGB stars

  11. Font, McCarthy, Crain et al. in prep.

  12. Concluzii • Predictiile modelului Lambda CDM sunt in general de acord cu observatiile • Directii de cercetare: • reconstructia in detaliu a procesului de formare a galaxiei noastre (when, what and how?) • este galaxia noastra o galaxie tipica? (cat din ceea ce intelegem despre Calea Lactee se poate extrapola si la alte galaxii spirale?)

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