Photometry of AGN
describes the light distribution in extended objects. It is widely used
is usually done by
to the isophotes.
This is motivated by the form of the isophotes mainly in elliptical and
lenticular galaxies. We get two types of output from these fits. First,
this is the residual image, which is the difference between the
original and the model image. Residual images are different for the
different types of galaxies and can also reveal asymmetric or weak
hidden structures. Second, we get radial profiles of the centre
position, ellipticity, position angle, intensity, deviations from
perfect elliptical isophotes and other quantities.
can be calculated from the sky subtracted intensity. They
can be integrated magnitudes within a certain aperture, or the surface
brightness at a given ellipse. Both can be transformed to a
standard photometric system with the use of standard stars.
The SP has produced up to now radial profiles
of a number of
parameters. A major task is to pick out of them the representative,
global ones. By fitting de Vaucouleurs law
an exponential law
or others to the galaxy surface brightness
the mean surface brightness Ie within re
, the central
intensity, the exponential disc scale factor and other physically less
meaningful parameters can be derived. We can determine a given global
parameter either as the extremum of the parameter profile or its value
at the effective radius or the value at a certain isophote, commonly
other criteria. Thus the global
ellipticity, position angle, colour, colour gradient (the slope of the
colour versus logr plot), etc. can be determined.
The global ellipticities and deviations from perfect elliptical
isophotes can be used to derive the relative disk
The measured values of logre
the line-of-sight stellar velocity dispersion, that stand in the
αlogre = α
do not populate this 3-parameter space evenly but are limited to a thin
plane - the Fundamental
. The FP combines SP with
spectroscopy.It can be used to study the evolution of galaxies
function of redshift
gives information about star population, dust content,
geometrical parameters and mass distribution in galaxies. SP has made
it possible to establish the distance scale in the Universeto and to
find the existence of different galaxy types and study
their global subsystems.
SP is a basic method in the study of distant galaxies. There exist 3
complicating the observational study of
galaxies. The first
cosmological dimming of surface brightness,
is the shifted
wave length of the moving object, compensated
by the so-called K-correction. Both factors originate from the Universe
expansion. The third
due to evolution of galaxy characteristics
Our publications - Surface Photometry
L., MIHOV B., PETROV G., BACHEV R., IAU Symp. 194, p.87, 1999.
Created by L.Slavcheva-Mihova, 2005
Spectrophotometry of selected AGN. Seyfert
galaxy Arakelian 564.
G., SLAVCHEVA L., BACHEV R., MIHOV
B., IAU Symp. 194, p.84, 1999.
Surface photometry of barred AGN. Arakelian
L., MIHOV B.,
Astron. Obs. Belgrade, 2004, 74, 1-2.
Surface photometry of NGC 5610 - A
Box/Peanut Structure In An Intermediately Inclined Galaxy.
L., PETROV G., MIHOV
Reserch in Bulgaria, 2005, 19
Multicolour Surface Photometry Of Seyfert
Galaxies: First Results.
G., SLAVCHEVA L., Astrophysical Investigations, 2006,
of barred AGN. Wolf Rayet galaxy NGC 6764.