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Robert
J. Trumpler Award
Steven Furlanetto
Harvard University, USA
As
the Universe expanded and cooled after the Big Bang, it underwent
several transitions, marked by eras during which it created first
baryons, then atoms, stars and finally galaxies as we see them today.
The period between the recombination of electrons and protons to
make the first neutral atoms at about 380,000 years after creation
and the subsequent reionization of these atoms when the first generation
of stars or quasars turned on is now referred to as the "Dark Ages."
The Dark Ages ended several hundred million years after recombination
in the so-called Epoch of Reionization, a time of great interest
to astrophysicists today. That is in part because studies of the
Epoch of Reionization (EoR) will tell us so much about the first
luminous objects to form in the Universe, and in part because several
planned, low frequency, radio arrays may soon detect and characterize
the EoR (through the redshifted 21 cm line of hydrogen, which is
strong in the pre-reionization Universe but disappears as the gas
is ionized).
We
honor Steven Furlanetto, the 2006 winner of the Trumpler Award,
for his contributions to our understanding of the Epoch of Reionization.
His thesis and the subsequent research derived from it have provided
important guidance to astronomers planning redshifted 21 cm observations
of the EoR. These include groups planning the Square Kilometer Array
and some of its smaller predecessors such as the Mileura Wide Field
Array (of which he is a team member). Furlanetto extended earlier
work by Chris Carilli of the National Radio Astronomy Observatory
to model the distribution of sizes and optical depths of the observable
features imprinted during the EoR. These calculations are serving
to guide the design of the experiments to characterize the EoR and
the sources of "first light" in the Universe.
Furlanetto’s
Harvard thesis produced five other novel and important astrophysical
results, all coauthored with his advisor, Abraham Loeb. One of these
explores a new mechanism for the generation of magnetic fields in
the intergalactic medium, an open and intriguing question in astrophysics.
The Furlanetto and Loeb paper argues that magnetic field originating
in the accretion disk around a central Black Hole in a galaxy can
be spread by outflows from the AGN. We see once again the close
link between the properties of galaxies and of their resident, central
Black Holes. Another of the papers derived from Furlanetto’s
thesis treats the 511 keV annihilation line from positrons produced
by relativistic jets from active Galactic nuclei. In addition to
its wide range, his thesis is praised for its mathematical sophistication,
originality and attention to detail. The papers derived from it
are already having a substantial impact on cosmology and extragalactic
astronomy generally, and the ASP is proud to highlight the excellence
of Steven Furlanetto’s thesis by presenting him the Trumpler
Award for 2006.
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