February 24
Renbin Yan (NYU)
The
Puzzle of LINERs and the Warm Ionized Gas in Early-type Galaxies
Ever since
their discovery, the nature of low ionization nuclear emission-line regions
(LINERs) has been hotly debated. Some authors treat them as AGNs, others argue
they are not AGNs but powered by shocks or hot old stars. No universal agreement has been reached.
On the other hand, early-type galaxies frequently contain spatially extended
warm ionized gas and have spectra similar to LINERs. How is this large-scale
emission related to the nuclear LINERs? Because LINER-like spectrum is the most
common spectral type found in early-type galaxies in both nuclear and
integrated spectra, understanding its nature is important to AGN demographics
and numerous other topics in astrophysics.
In this talk,
you will hear a story of how I converted from a supporter for AGN-powering of
LINER line emission to an opponent, and what kind of convincing evidence I find
made me convert. I will also discuss what we can learn about the warm ionized
gas in early-type galaxies from this line emission, given that it is not an AGN
indicator.