Published in "Extragalactic Background Radiation", Space
Telescope Science Institute Symposium Series 7, 1995, eds. D. Calzetti,
M. Livio and P. Madau
EXTRAGALACTIC ULTRAVIOLET BACKGROUND RADIATION
Richard C. Henry
Center for Astrophysical Sciences,
Henry A. Rowland
Department of Physics and Astronomy,
The Johns Hopkins
University, Baltimore, MD 21218
and
Space Astronomy and Astrophysics Group,
Los Alamos
National Laboratory
Jayant Murthy
Center for Astrophysical Sciences,
Henry A. Rowland
Department of Physics and Astronomy,
The Johns Hopkins
University, Baltimore, MD 21218
Abstract. We describe observations of the cosmic background in
the far ultraviolet. If
the Voyager upper limit on the cosmic diffuse ultraviolet background at
1100 Å at some
locations is accepted as correct, the spectrum of the high-galactic
latitude background
is most remarkable, featuring an abrupt rise at about 1216 Å. Such
a rise suggests an origin in redshifted Lyman
recombination radiation, but
that explanation requires
the existence of an ionization source such as the radiative decay of
massive neutrinos
to maintain the ionization. We therefore explore a more conservative
origin in the
scattered light of galactic plane OB stars. This explanation is fraught
with difficulties:
a dust population specially invented for the purpose seems to be
required. This ad hoc
explanation may be preferred by some; a perhaps somewhat exotic
extragalactic origin
by others. Quite simple additional observations should clarify matters
considerably.
Table of Contents
