Eötvös Loránd Tudományegyetem
Természettudományi Kar
Fizikai Intézet







mesterszakos diplomatéma részletei

A kiíró adatai
Név: Haiman Zoltan
Tudományos fokozat: PhD
Intézet: Department of Astronomy Columbia University 1328 Pupin Physics Laboratories Mail Code 5246 550 West 120th Street New York, NY, 10027, USA
Telefonszám: +1 212 854 6822
Honlap: http://www.astro.columbia.edu/~zoltan


A mesterszakos diplomatéma:
Címe: How massive were the first stars in the universe?
A munka jellege: elméleti
Szakterületi besorolás: Asztrofizika, kozmológia
A téma rövid leírása: The first generation of stars must have formed out
of gas with primordial composition, containing only
hydrogen and helium, and no significant amounts of
other elements.
It has long been thought that H_2 molecules are the
dominant source of radiative cooling in the gas in the
first minigalaxies at redshift z=20. Because H_2 can
not cool the gas to temperatures below ~200 K, the
first stars would have been very massive (100 times
more massive than the sun). Recent work, however,
has shown that under special circumstances, HD
molecules can cool the gas to temperatures much lower
than allowed by H2 cooling alone. This would have
important implications for the properties of the first
stars, and on the subsequent evolution of the rest
of the universe, as well.
The recent calculations involving HD have so far
ignored the photo-dissociation of HD. It would be
crucial to know whether HD is an important coolant
even in the face of photodissociating UV radiation
expected to be present in the high-redshift universe.
Szükséges előismeretek: the student shoudl be familiar with basic concepts in cosmology and in radiative processes, and should have experience solving differential equations
Egyetemi konzulens: Frei Zsolt


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