File:COSMOS survey.jpg

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English: A team of astronomers studied over 1400 galaxies snapped by Hubble in the COSMOS survey, to test the hypothesis that galactic mergers trigger active galactic nuclei (AGN). In order to make this a blind test, the team modelled and removed the active nucleus (which normally appears as a bright spot) from each galaxy, and then cosmetically added a similar mark to the galaxies without an AGN, to make them visually indistinguishable. This explains the black dot visible near the centre of each of these images.

They then categorised the galaxies, according to whether they showed no sign of recent mergers (top), minor signs (middle row) or clear signs of disruption from a recent merger (bottom).

Analysing these results, they found that galaxies with active nuclei (left) and those with inactive nuclei (right) showed no statistically significant difference in the proportion that had undergone mergers. This means that processes other than galactic mergers must trigger AGN activity.
Date
Source http://www.spacetelescope.org/images/heic1101a/
Author NASA, ESA, M. Cisternas (Max-Planck Institute for Astronomy)
Permission
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Public domain This file is in the public domain because it was created by NASA and ESA. NASA Hubble material (and ESA Hubble material prior to 2009) is copyright-free and may be freely used as in the public domain without fee, on the condition that only NASA, STScI, and/or ESA is credited as the source of the material. This license does not apply if ESA material created after 2008 or source material from other organizations is in use.
The material was created for NASA by Space Telescope Science Institute under Contract NAS5-26555, or for ESA by the Hubble European Space Agency Information Centre. Copyright statement at hubblesite.org or 2008 copyright statement at spacetelescope.org. For material created by the European Space Agency on the spacetelescope.org site since 2009, use the {{ESA-Hubble}} tag.

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5 January 2011

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current16:46, 21 January 2011Thumbnail for version as of 16:46, 21 January 20112,650 × 1,964 (1.22 MB)Jmencisom{{Information |Description={{en|1=A team of astronomers studied over 1400 galaxies snapped by Hubble in the COSMOS survey, to test the hypothesis that galactic mergers trigger active galactic nuclei (AGN). In order to make this a blind test, the team mode

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