 |
 |
Astron. Astrophys. 332, 739-747 (1998)
Available formats: HTML | PDF | (gzipped) PostScript
Small-scale structures in the far-infrared background *
Uwe Herbstmeier 1,
Péter Ábrahám 1, 2,
Dietrich Lemke 1,
R.J. Laureijs 3,
Ulrich Klaas 1, 3,
Kalevi Mattila 4,
Christoph Leinert 1,
Christian Surace 1 and
Michael Kunkel 1
1 Max-Planck-Institut für Astronomie, Königstuhl
17, D-69117 Heidelberg, Germany
2 Konkoly Observatory of the Hungarian Academy of Sciences,
P.O. Box 67, 1525 Budapest, Hungary
3 ISO Science Operation Centre, Astrophysics Division,
Space Science Department of ESA, Villafranca, P.O. Box 50727, E-28080
Madrid, Spain
4 University of Helsinki, Observatory, P.O. Box 14,
Tähtitorninmäki, FIN-00014 Helsinki, Finland
Received 22 September 1997 / Accepted 20 January 1998
Abstract
Four fields with areas ranging from 80 to 2000 arcmin2
have been mapped with the photometer on board of the Infrared Space
Observatory (ISO) at 90 and around 180 µm in regions of
bright and faint cirrus. We examined the spatial characteristics of
the infrared background emission with high spatial resolution and
found that the fluctuations in the background emission limit the
detection sensitivity of ISOPHOT for most of our observations. At
90 µm the power law relation between the power in the
fluctuations and the spatial frequencies established from IRAS data
could be extended to twice as high spatial frequencies. At
180 µm the small-scale fluctuations were studied for the
first time by a cold space telescope with arcminute-resolution. A
similar power law and spectral index down to spatial scales of
![[FORMULA]](img1.gif)
as for the 90 µm component is
found. For cirrus clouds the spatial frequency spectrum in the
far-infrared has a similar shape as that derived from 21 cm line
observations of the interstellar neutral hydrogen. In faint regions
the fluctuations are caused presumably by randomly distributed
extragalactic sources. Future 3 m class space telescopes surveying the
sky around 200 µm will not be hampered by cirrus over
most of the sphere.
Key words: methods:
observational 
ISM: structure
Infrared: ISM:
continuum
diffuse radiation
* Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA
Send offprint requests to: Uwe Herbstmeier (uherbst@mpia-hd.mpg.de)
© European Southern Observatory (ESO) 1998
Online publication: March 23, 1998
helpdesk@link.springer.de