Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2010-02-11
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
18 pages, 19 figures, 1 table. Accepted for publication in MNRAS
Scientific paper
We assess the effects of simulated active galactic nuclei (AGNs) on the colour and morphology measurements of their host galaxies. To test the morphology measurements, we select a sample of galaxies not known to host AGNs and add a series of point sources scaled to represent specified fractions of the observed V band light detected from the resulting systems; we then compare morphology measurements of the simulated systems to measurements of the original galaxies. AGN contributions >20 per cent bias most of the morphology measurements tested, though the extent of the apparent bias depends on the morphological characteristics of the original galaxies. We test colour measurements by adding to non-AGN galaxy spectra a quasar spectrum scaled to contribute specified fractions of the rest-frame B band light detected from the resulting systems. A quasar fraction of 5 per cent can move the NUV-r colour of an elliptical galaxy from the UV-optical red sequence to the green valley, and 20 per cent can move it into the blue cloud. Combining the colour and morphology results, we find that a galaxy/AGN system with an AGN contribution >20 per cent may appear bluer and more bulge-dominated than the underlying galaxy. We conclude that (1) bulge-dominated, E/S0/Sa, and early-type morphology classifications are accurate for red AGN host galaxies and may be accurate for blue host galaxies, unless the AGN manifests itself as a well-defined point source; and (2) although highly unobscured AGNs, such as the quasar used for our experiments, can significantly bias the measured colours of AGN host galaxies, it is possible to identify such systems by examining optical images of the hosts for the presence of a point source and/or measuring the level of nuclear obscuration.
Coil Alison L.
Conselice Christopher J.
Faber Sandra M.
Griffith Roger L.
Ivison Rob J.
No associations
LandOfFree
The Effects of an AGN on Host Galaxy Colour and Morphology Measurements does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Effects of an AGN on Host Galaxy Colour and Morphology Measurements, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Effects of an AGN on Host Galaxy Colour and Morphology Measurements will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-68788