Contents of: VI/111/./abstract/RCHINI_RCQSO01.abs

The following document lists the file abstract/RCHINI_RCQSO01.abs from catalogue VI/111.
A plain copy of the file (without headers/trailers) may be downloaded.


SCIENTIFIC ABSTRACT
Most objects with cosmological redshift (z > 0.5) have been found by means
of their radio emission (radio loud quasars and radio galaxies) or due to
their optical emission lines (radio quiet quasars). Very little is known about
the FIR spectra of these objects since IRAS could obtain spectra only for
the 50 brightest members of this class. On the other hand, it is just the
range between 20 and 200 microns where one expects the thermal emission to
overrun the non-thermal radiation dominating the radio regime. Thus FIR
spectra should show both the shortest wavelengths of non-thermal and the
longest wavelengths of thermal continuum emission which are of great
importance for a theoretical understanding of the various emission pro-
cesses and their origin in the cores of AGNs.
We propose to measure the spectrum of several carefully selected quasar
samples between 5 and 200 microns with ISOPHOT-P and ISOPHOT-C in order to
identify the different components. This will be done by quasi-simultaneous
multi-band photometry. Polarization and variability studies which can
even clearer distinguish between synchrotron and other components will be
performed for a few key objects.
Evolutionary trends will be investigated by measuring quasars in the
redshift range between 0.1 and 4.5. Observations of a sample of radio gal-
axies from the 3C-Catalogue will test whether the unified schemes are
viable which interpret radio galaxies as quasars seen under distinct angles.
The total spacecraft time of the proposal is 35 hours with a mean
observing efficiency of 45 %.

OBSERVATION SUMMARY
The continuum emission of quasars between 4.8 and 200 microns will be traced
with ISOPHOT-P in six filters (P_4.85, P_7.3, P_12.8, P_20, P_60, P_100) and
ISOPHOT-C (C_160) in order to obtain an almost complete and simultaneous energy
distribution. The apertures are 23arcsec (4.85 to 20 microns) and 99arcsec (60
and 100 microns), the chopper throw is 120arcsec for the P-filters and 180
arcsec for the C-filter. A total observing time of 855sec per low redshift
quasar will result in a S/N of about 3 at 4.8 micron and more than 100 at 160
microns (on source integration times: 32s in P_4.85, 64s in P_7.3, 16s in the
remaining bands). The high redshift objects are much fainter and will be
observed only in P_12.8 (256s on-source), P_20 (256s), P_60 (128s), P_100 (32s)
and C_160(64s) resulting in a total time of 1957 sec per object. The
observations comprise various QSO samples  which are selected by the
visibility constraints of ISO, i.e. 3CR sources (30 objects, 6.4h),
3Jy catalog + BLL (35 objects, 7.6h), high-z QSOs (9 objects, 4.9h) and PG
sources (24 objects 5.2h).

The multi-band photometry should be repeated for 3 radio-loud QSOs (3C273,
FR_0133+476, FR_0208-512 (spring) or 3C273, 3C345, BL_2155-152 (autumn)) 
within weeks and for 2 optically selected QSOs (1613+658, 1634+706 (autumn 
launch) or 0946+301, 0953+414 (spring launch)) within intervals of several 
months. In total 35 measurements (8.3h) are proposed to study the variability 
on different time scales.

Four sources will be examined by polarimetric observations at 90 microns
in order to distinguish between thermal and non-thermal contributions. In order
to achieve a polarization error of less than 0.5%, on average 850sec of
observing time per source are required.



© Université de Strasbourg/CNRS

    • Contact