a prescription for high-redshift star formation
DESCRIPTION
A Prescription for High-Redshift star formation. Alexander (Sasha) Muratov University of Michigan Advisor: Oleg Gnedin. Star Formation History of The Universe. Madau et al. 1996. State of Simulations. - PowerPoint PPT PresentationTRANSCRIPT
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A Prescription for High-Redshift star formation
Alexander (Sasha) MuratovUniversity of Michigan
Advisor: Oleg Gnedin
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Star Formation History of The Universe
Madau et al. 1996
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State of Simulations
• Collisionless dark matter simulations can be run with great resolution down to zero redshift, but what are the stars and gas doing?
Kravtsov et al. (2004)
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Prescriptive Model: Advantages
All quantities available at all times Made to be consistent with observations and
simulations Can provide insight into global processes on
different scales: Star Formation. Makes testable predictions. Disadvantages: makes testable predictions – need to
match many data sets. Sometimes difficult to constrain.
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Observed fitsM
*-M
h relation (Woo et al. 2008)
logVc = -0.5 + .27logM* , M
* ~ Vc
3.8
Vc = V
max * 2½
Mh ~ V
max3.3
M*-Mgas relation (McGaugh 2005)
Mass metallicity relation: Woo et al. (2008)
Ms(z=0) = 109.6 MꙨ
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Observed fits 2 – time evolution Dave & Oppenheimer
(2007).3 dex lower over 10 Gyr
Conroy & Wechsler (2008)Well fit by M
* ~ (1+z)-2
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Equations again
• Mass
MW = 5.5 * 10^10 Solar (M*)
MW = 1 * 10^10 Solar (Mgas)
• Metallicity:
extra constraints:
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fgas(z, M)
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Anchored by GC's
• DM halos from Kravtsov et al. (2004)
• Hydro constraints from Kravtsov & Gnedin (2005)
• Bimodal metallicity distribution! (Muratov & Gnedin, in prep)
• KS Probablity: 51%
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prediction for stellar fraction in dwarf galaxies
• M* = -1.85 + 1.03*Mh
• RMS: 0.212
• Red Line : Andrey Kravtsov's relation (2009)
• Different techniques used: instead of matching brightest to most massive, we apply direct relations.
• Which is right?
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Summary
• We present a prescriptive model for baryonic mass and metallicity as a function of time and halo mass.
• Applying this prescription to DM simulations, we have studied GC formation.
• We also obtain a fit for MW Dwarfs. Produces a different result from Kravtsov 2009, Busha 2009.