Peter Michaud
Science Highlights
Figure 1.
Minimum ionizing
luminosity of extended
AGN-ionized clouds
along the projected
radius. These Hubble
Space Telescope data
show a luminosity
drop in the last 20,000
years before our direct
view of the nucleus,
characteristic for all
AGN of this study.
Gemini follow-up on fading active galactic nuclei (AGN) help
confirm that they are dynamically different from radio-loud AGN.
Gemini Multi-Object Spectrograph data assist astronomers in seeing
for the first time clear signatures of rocky planet assembly via large
asteroids in a dwarf binary system. And Gemini Planet Imager data
reveal that exoplanet β Pictoris b appears to have an atmosphere
similar to those found around low-surface-gravity brown dwarfs.
New Insights on Fading Active Galactic Nuclei in Collaboration
with Galaxy Zoo
William C. Keel (University of Alabama) and collaborators use Hα narrowband filters on the
Hubble Space Telescope (HST), in conjunction with the Gemini Multi-Object Spectrograph
integral field unit (GMOS IFU) on the Gemini North telescope on Maunakea, to observe a
set of fading active galactic nuclei (AGN). These AGN
were first identified/classified as part of the Galaxy
Zoo project — an online citizen science project in
which the public help researchers deal with floods
of incoming data aimed at classifying galaxies.
This work focuses on nine AGN with ionized gas
clouds extending more than 10 kiloparsecs from
them. Because these clouds span galaxy scales (or
even larger) they can implicitly tell us about the lu-
minosity history of the AGN. Based on this research,
the nine observed AGN appear to have experienced
a significant reduction in luminosity within 20,000
years or less (Figure 1).
12
GeminiFocus
April 2017