==================================================================== ==> in this proposal, more time is being requested for gserra.szclust ==================================================================== the spectral distorsion of the microwave cosmic background radiation by inverse compton scattering in the hot intracluster electron gas (the so-called sunyaev zel.dovitch effect, sz thereafter) is potentially a powerfull tool of observa- tional cosmology. measurements of this distorsion in the submillimeter to centimeter range, used in conjunction with x ray data, allows the determination of important parameters such as the total cluster gas mass, its peculiar velocity and the hubble constant. reliable measurements of the negative part of the effect become now available at millimeter and centimeter wavelengths. however, the knowledge of the positive part at submillimeter wavelengths is also required in order to derive the physical parameters. such measurements are now within the reach of the pronaos/spm balloon borne submillimeter instrument. the flight of the instrument sept. 22/23 1996 has revealed an excellent sensitivity. data have been accumulated on four clusters : a 478, a 2142, a 2163 and a 2218. they need a refined analysis for a possible detection of the positive sz effect. in the submilliteter range, emission from the galaxies in the cluster and fore- ground dust in our galaxy are expected to be comparable or larger than the cosmological signal, and will polute the sz measurement. individual galaxies contributing significantly must therefore be identified, and their submillimeter flux be measured with enough accuracy to allow a precise subtraction. due to its wavelength coverage iso will offer a unique opportunity to make these measurements toward clusters for which detection of the positive part is foreseen in the near future. we therefore propose to observe several clusters with phot (90 and 180 um) and cam (15 um). the clusters selected for this program are all massive clusters, for which a good measurement of the negative sz effect is available. the proposed observations will form a unique and homonegeous data set on the best sz clusters for the next coming years.
Instrument
CAM01 , PHT22 , PHT32
Temporal Coverage
1997-03-04T07:10:44Z/1998-02-21T16:14:03Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
