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Mon. Not. R. Astron. Soc. 384, 420439 (2008) doi:10.1111/j.1365-2966.2007.12723.x Image decomposition of barred galaxies and AGN hosts

Summary: Mon. Not. R. Astron. Soc. 384, 420­439 (2008) doi:10.1111/j.1365-2966.2007.12723.x
Image decomposition of barred galaxies and AGN hosts
Dimitri Alexei Gadotti
Max-Planck-Institut f¨ur Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching bei M¨unchen, Germany
Accepted 2007 November 14. Received 2007 November 12; in original form 2007 August 21
I present the results of multicomponent decomposition of V and R broad-band images of a
sample of 17 nearby galaxies, most of them hosting bars and active galactic nuclei (AGN).
I use BUDDA v2.1 to produce the fits, allowing the inclusion of bars and AGN in the models.
A comparison with previous results from the literature shows a fairly good agreement. It is
found that the axial ratio of bars, as measured from ellipse fits, can be severely underestimated
if the galaxy axisymmetric component is relatively luminous. Thus, reliable bar axial ratios
can only be determined by taking into account the contributions of bulge and disc to the light
distribution in the galaxy image. Through a number of tests, I show that neglecting bars when
modelling barred galaxies can result in an overestimation of the bulge-to-total luminosity
ratio of a factor of 2. Similar effects result when bright, type 1 AGN are not considered in
the models. By artificially redshifting the images, I show that the structural parameters of
more distant galaxies can in general be reliably retrieved through image fitting, at least up
to the point where the physical spatial resolution is 1.5 kpc. This corresponds, for instance,
to images of galaxies at z = 0.05 with a seeing full width at half-maximum (FWHM) of


Source: Alexei, Dimitri - European Southern Observatory


Collections: Physics