Dating COINS: Kinematic Ages for Compact Symmetric Objects

We present multi-epoch VLBA observations of Compact Symmetric Objects (CSOs) from the COINS sample (CSOs Observed In the Northern Sky). These observations allow us to make estimates of, or place limits on, the kinematic ages for those sources with well-identified hot spots. This study significantly increases the number of CSOs with well-determined ages or limits. The age distribution is found to be sharply peaked under 500 years, suggesting that many CSOs die young, or are episodic in nature, and very few survive to evolve into FR II sources like Cygnus A. Jet components are found to have higher velocities than hot spots which is consistent with their movement down cleared channels. We also report on the first detections of significant polarization in two CSOs, J0000+4054 (2.1%) and J1826+1831 (8.8%). In both cases the polarized emission is found in jet components on the stronger side of the center of activity. Subject headings: galaxies: active – galaxies: ISM – galaxies: jets – galaxies: nuclei – radio continuum: galaxies Lycoming College, Williamsport, PA 17701 National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 Kavli Institute of Particle Astrophysics and Cosmology, Menlo Park, CA 94025 Harvard-Smithsonian CfA, SAO/SMA Project, 645 N. A’ohoku Pl., Hilo, HI 96720 Istituto di Radioastronomia del CNR, via Gobetti 101, 40129 Bologna, Italy Work supported in part by the Department of Energy contract DE-AC02-76SF00515. astro-ph/0412199 SLAC-PUB-10889 Submitted to Astrophysical Journal Kavli Institute of Particle Astrophysics and Cosmology, Stanford Linear Accelerator Center, 2575 Sand Hill Road, Menlo Park, CA 94025