Search for distant radio galaxies in SAO
The search for distant objects which can be both galaxies and quasars
is one of the most important problems of observational astrphysics,
because it allows one to determine cosmological parameters connected
with the time of appearence and evolution of stellar systems,
large scale structure of the Universe.
Discoveries of 1998 yr show the galaxies (i.e. objects with the stellar
population) are the most distant objects. They can have redshifts
Z up to 7. And theoretical models give for galaxies formation epoch
Z up to 17.
One of the most interesting problems in this direction is a search for
distant radio galaxies, i.e. extended objects having radio emission and
being to the current moment the eldest objects of the radio Universe
after microwave background radiation.
This problem (the search for distant radio galaxies) is a part of
the project "Early Universe",
which is described in SAO (Nizhnij Arkhyz):
<click here> ,
and in St.Petersburg:
<click here>.
Radio galaxies are important objects to be studied because they are
sources of infrared-optical-ultraviolet continuum, emission lines
and continual radio emission. Since all the components of their
radiation have an extended structure, these objects can be investigated
by the ground based telescopes.
Fanaroff and Riley in 1974 identified 2 types of radio galaxies
depending on their structure which are named now as FRI and FRII.
Radio galaxies of the first type have radio emission decreasing to the
sides of a radio source, radio galaxies of the second type
have distribution of radio emission mostly concentrating in sidelobes,
so called "hot spots".
Radio galaxies are, generally, identified with elliptical galaxies.
Radio galaxies in cluseters are identified with giant elliptical galaxies
or cD-galaxies being the most powerful radio sources in clusters of galaxies
and formed, apparantly, by the spiral galaxies merging.
Some radio galaxies are identified with N-galaxies.
The diatant radio galaxies(Z>1) are especially interesting
because they are probers of the epoch of galaxy formation in protoclusters
(or in cluseters). Besides, the detection of Ly in surrounding matter
can help to investigate neutral gas at high redshifts and to check
the galaxy formation models.
A team of atronomers
searches for and studys distant radio galaxies for several
years in the Special astrophysical observatory .
This team is headed
by Prof. Yurij Parijskij and
Prof. Natalia Soboleva.
The main optical observer of the team is
Dr. Alexander Kopylov.
The following people are also work in this team:
Dr. Adelina Temirova
(analysis of radio and optical data),
Olga Zhelenkova
(data reduction in MIDAS, radio sources identification on the
optical images),
Dr. Oleg Verkhodanov (software
design, operation with SED (Spectral Energy
Distribution) curves, ages estimation and observations).
The project of the SAO for the serach for distant radio galaxies,
called "Big Trio" (because it unifies 3 big telescopes
RATAN-600 -
VLA -
BTA),
allows one to penetrate into "the Dark ages"
with redshifts 7<Z<30 from the
"low" values.
The project of the study of distant radio galaxies consists of
several steps:
- selection of radio sources with steep spectra (spectral index
< 1) mostly with flux densities from 10 till 100 mJy
in the centimeter wavelength range at
RATAN-600.
The catalog
"Cold".
is used for this goal.
- Defenition of a sources structure with the radio interferometer
VLA.
- Selection of double radio sources (radio galaxies) having a structure
of the FRII type.
- Observations at 6m
telescope of SAO RAS to
identify
objects and to obtain multicolor photometry and redshift.
- Estimaition of ages of the stellar population of elliptical
galaxies and measurement/estimation of redshifts of identified
objects in various evolutional models.
One may read about results of the "Big Trio" project
in the following papers:
-
Kopylov A.I., Goss W.M., Parijskij Yu.N., Soboleva N.S.,
Temirova A.V., Zhelenkova O.P., Vitkovskij Val.V., Naugolnaya M.N.,
Verkhodanov O.V. 1995. Optical identifications of subsample of
steep spectra radio sources from RC catalog using 6m SAO telescope
of SAO RAS: optical observations. Astronomicheskij Zhurnal (Russia).
V.72. No.5. P.613-629.
-
Kopylov A.I., Goss W.M., Parijskij Yu.N., Soboleva N.S.,
Temirova A.V., Zhelenkova O.P., Vitkovskij Val.V., Naugolnaya M.N.,
Verkhodanov O.V. 1995. Optical identifications of subsample of
the RC catalog steep spectra radio sources with 6-meter telescope
of SAO RAS. Requirements to coordinate precision and the
image depth, VLA observations and photometric methods of
redshift estimation. Astronom. Zh. (Russia).
V.72. No 4, P.437-446.
-
Parijskij Yu. N., Goss W.M., Kopylov A.I., Soboleva N.S.,
Temirova A.V.,Verkhodanov O.V., Zhelenkova O.P., Naugolnaya M.N.
Investigation of RATAN-600 RC radio sources.
Bulletin SAO, No 40, 1996, P. 5-124.
-
Parijskij Yu.N., Soboleva N.S., Verkhodanov O.V.,
Kopylov A.I., Zhelenkova O.P. On observations of diffuse
optical emission along the axis of double radio
sources of RC catalog at the 6 m optical telescope.
Bulletin of SAO, No 40, 1996, P. 125-127.
-
A. Fletcher, S. Conner, F. Crawford, J Cartwright, B. Burke,
Yu. N. Pariiskii, N.S. Soboleva, A.I. Kopylov, A.V. Temirova,
O.V.Verkhodanov, M.N. Naugol'naya. 1996.
Identification of Objects from the RC Catalog with Accuracy
Eceeding 1" using the Palomar Prints and VLA maps from
the MIT Archive. Astronomy Reports (distr. by American
Institute of Physics). V.40, No. 6, 759-767. (in Russian:
Astronomicheskij Zhurnal V.73, No 6, 1996, 835-843.).
-
Y.Parijskij, A.Kopylov, N.Soboleva, O.Verkhodanov, A.Temirova,
O.Zhelenkova, P.Tcibulev, A.Chepurnov, V.Stolyarov and N.Bursov.
1998. "Dark ages" of the Univese.
In "Current Topics in Astropfundamental
Physics: Primordial Cosmology", eds N.Sancher and A.Zidini.
(Erice, Italy, 4-15 Sept., 1997)
Kluwer Academic Publisher. P.443-466.
-
Pariiskii Yu. N., Goss W. M., Kopylov A. I., Soboleva N. S.,
Temirova A. V., Verkhodanov O. V., Zhelenkova O. P. 1998.
Completion of the Optical Identification of RC Catalog Objects with
Ultra Steep Spectra and Estimation of Their Redshifts.
Astronomy Reports, V.42, P. 425.
-
Pursimo, T.; Nilsson, K.; Teerikorpy, P.; Kopylov, A.;
Soboleva, N.; Parijskij, Yu.; Baryshev, Yu.; Verkhodanov, O.;
Temirova, A.; Zhelenkova, O.; Goss, W.; Sillanpaa; A.;
Takalo, L.O. 1999.
Optical morphology of distant RATAN-600 radio galaxies
from subarcsecond resolution NOT images. Astron. Astrophys.
134, P.505
Some results for 1998:
RC 0105+0501(Russian KOI8)
vo@sao.ru
(Oleg Verkhodanov)