An INTERVIEW with
Raffaella Schneider
ESI Special Topics, May
2004
Citing URL - http://www.esi-topics.com/blackholes/interviews/RaffaellaSchneider.html
 n this
interview, Dr. Raffaella Schneider discusses her work on the
paper "First stars, very massive black holes, and
metals" (Astrophysical Journal 571: 30-9, 2002).
According to our Special Topics analysis on black holes
research, this paper is ranked at #3 among papers published on
black holes in the past two years, with 44 citations. Dr.
Schneider is a postdoc in the cosmology group at the Arcetri
Astrophysical Observatory in Firenze, Italy.
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 What
are the circumstances which led you to your work?
The Arcetri Astrophysical Observatory, where I have been working
for the past three years in collaboration with Andrea Ferrara, has a
wide and long-standing experience in primordial star formation and
high-redshift cosmology. In particular, I had the great opportunity
of interacting both with experts in the physics of star formation in
primordial environments and with experts in numerical simulations
and galaxy evolution. This was a fundamental condition that enabled
me and my collaborators to explore the impact of the first stellar
population and its dark remnants on the overall cosmic evolution. In
particular, Kazuyuki Omukai and Priyamvada Natarajan were both
visiting the Arcetri Observatory in spring 2002. This 
circumstance was critical for the work because Kazuyuki Omukai was
able to modify his primordial star formation model to study the
effects of heavy elements in the fragmentation properties of star
forming clouds; moreover, the interaction with Priyamvada Natarajan
was very important to assess the observational consequences of the
population of black-hole-remnants relics of the first stellar
generation.
Would
you describe the significance of this work for your field?
Our work has been aimed at understanding the conditions that
enable the transition from a first stellar population, characterized
by very massive stars, with characteristic masses a hundred times
that of the Sun, to an evolved stellar population forming with
characteristic masses comparable to that of the Sun and with
properties closer to those that we presently observe in the local
universe. We were able to define a physically reliable scenario in
which this transition was driven by an increased abundance of heavy
elements ("metals") above a critical threshold. This
critical metallicity scenario now appears to be widely discussed,
though its observational confirmation will have to await the next
generation of space telescopes, such as the James Webb Space
Telescope that will be launched in 2010.
Where
has this research gone since the publication of your paper?
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“My hope is that over the next 10 years we will be able to constrain the initial mass function of the first stars and to directly image the light emitted by these first stellar sources.” |
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The study of the properties of the first stars and of their role
in cosmic evolution is a very active and expanding research field. A
number of papers have appeared to assess the impact of the first
stellar generation on metal enrichment and the reionization of the
universe, particularly after the release of the first-year data of
the Wilkinson Microwave Anisotropy Probe satellite, which showed
that the universe was reionized earlier than previously thought,
requiring substantial star formation to have occurred at high
redshift.
Numerous papers have appeared giving predictions on the star
formation and reionization histories of the universe which take into
account the critical metallicity scenario through the so-called
chemical feedback of the first stellar populations on subsequent
stellar generations.
Where
do you see it going 10 years from now?
I expect that there will be a substantial advancement in
understanding the properties of the first stars, in particular the
role of various feedbacks during mass accretion onto the forming
protostar, which are now only partially understood. The increasing
number of observational campaigns that are pushing the frontier of
the observable universe to higher and higher redshift will provide a
wide variety of data to compare with the models.
My hope is that over the next 10 years we will be able to
constrain the initial mass function of the first stars and to
directly image the light emitted by these first stellar sources.
Raffaella Schneider, Ph.D.
Arcetri Astrophysical Observatory
Firenze, Italy
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ESI Special Topics, May
2004
Citing URL - http://www.esi-topics.com/blackholes/interviews/RaffaellaSchneider.html
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