Transcript Andreea Font - Formarea Galaxiilor de tip Caleea Lactee

Formarea Galaxiilor de tip
Caleea Lactee
(Simulari cosmologice)
Andreea Font
Institute of Astronomy, University of Cambridge
Workshop Exploratoriu ‘Astronomia Romaneasca’, Sep 22-23, 2010
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
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.
Metode computationale
I. Metode Semi-analitice:
- combina simulari N-body (dinamica)
cu tratament semi-analitic a proceselor
fizice (atomi, molecule, radiatie)
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
Virgo Consortium for
Cosmological Simulations
UK, Germany, Canada,
Netherlanda, USA, Japan
Resources:
-“Cosmology Machine” (Durham)
792 opteron cpus +500 ultrasparcIII 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
Ratii ale elementelor chimice in stele
stellar halo
[α/Fe]
How do we make
this...
.. from this?
dSph dIrr
satellite
data from Venn 04
stars
[Fe/H]
Venn et a.
(2004)
[α/Fe]
Halo is alphaenhanced because
it is formed from
earlier accretion
events.
Surviving satellite
galaxies are
accreted later
data from Venn 04
[Fe/H]
Font et al 2006
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…
Metode Computationale
II. 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
Font, McCarthy, Crain et al. in prep.
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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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