I review the basic properties of low-ionization nuclear emission-line regions (LINERs), as well as the main ionization mechanisms thus far proposed for them. There is substantial heterogeneity among LINERs, especially those with extended kpc-scale emission. An extensive survey by Ho, Filippenko, & Sargent quantifies with unprecedented accuracy the optical emission-line intensity ratios in the n...

Ever since the co-existence of an active galactic nucleus (AGN) and a starburst was observationally discovered, there has been a significant controversy over whether there is a physical connection between starbursts and AGNs. If yes, it is a subject of interest to reveal which one triggers another. Here we bring a unique insight onto the subject by identifying 840 galaxies with both a post-star...

UNJ1025−0040 is a quasar at z = 0.6344 that shows an extremely bright post starburst population of age ∼ 400 Myr (Brotherton et al. 1999). Images of UNJ1025−0040 show a nearly stellar object 4. 2 SSW of the quasar. We present imaging and spectroscopy that confirm that this object is a companion galaxy at redshift z = 0.6341. We estimate an age of ∼ 800 Myr for the dominant stellar population in...

Arcsec-resolution VLA observations – newly obtained as well as published – of 40 nearby galaxies are discussed, completing a study of the radio properties of a magnitude-limited sample of nearby galaxies of the composite LINER/H ii type. Our results reveal an overall detection rate of at least 25% AGN candidates among these composite sources. The general properties of these AGN candidates, as c...