MMTF Discovery of Giant Ionization Cones in MR 2251-178: Implications for Quasar Radiative Feedback

We report the discovery of giant ionization cones in the 140-kpc nebula around quasar MR 2251-178 based on deep [O III] 5007/H-beta and [N II] 6583/H-alpha flux ratio maps obtained with the Maryland-Magellan Tunable Filter (MMTF) on the Baade-Magellan 6.5m telescope. These cones are aligned with the weak double-lobed radio source observed on smaller scale <30 kpc). They have an opening angle ~120deg +/- 10deg and subtend ~65-90% of 4pi steradians, where the large uncertainty takes into account possible projection effects. The material in the outer ionization cones is matter-bounded, indicating that all ionizing photons emitted through the cones escape from the system. The quasar ionizing flux is ~2-3 times fainter outside of these cones, despite the largely symmetric geometry of the nebula in [O III]. Overall, adding up the contributions from both inside and outside the cones, we find that ~65-95% of the quasar ionizing radiation makes its way out of the system. These results emphasize the need for line ratio maps to quantify the escape fraction of ionizing radiation from quasars and the importance of quasar radiative feedback on the intergalactic medium.Comment: 9 pages, 4 figures, 1 table. Accepted for publication in ApJ Letter

HST Long Slit Spectroscopy of NGC 1068 and NGC 4151

Advisor: Charles NelsonNGC 1068 annd NGC 4151 are Seyfert Galaxies, the most common type of active galaxy, in which a luminous nucleus is powered by accretion onto a massive black hole at its center. Seyfert galaxies are known to exhibit high velocity outflows from their nuclei, however, the driving mechanisms are not fully understood. Typically, they are attributed to a nuclear wind, which blows material away from the nucleus in a bi-polar conical flow, or to interactions with a radio jet, which would expel material perpendicularly away from the jet axis. Using spectroscopic observations taken by the Hubble Space Telescope we are studying the structure and motion of the ionized gas clouds in these two objects, to understand the nature and origin of the flow. We compare our data with models of the gas kinematics to identify regions in these galaxies that display the signatures of a nuclear wind, jet-gas interaction, or both. We also measure the relative strengths of specific emission lines produced by these clouds to provide information about the ionization state of the clouds themselves. Preliminary results show high velocity gas flows in both galaxies and indicate that both jet and wind processes may be operating.Drake University, College of Arts and Sciences, Department of Physics and Astronom

Powerful Outflows in Seyfert Galaxies : Wind- Vs. Jet-Driven Models

Advisor: Charles NelsonSeyfert galaxies are active galaxies characterized by luminous outflows from a central super massive black hole. The outflow mechanism has not been fully determined, but the two primary competing systems are a wind-driven conical outflow and a jet-driven cylindrical outflow. We are developing models with a variety of parameters, including inclination, cone opening angle, etc. By varying these parameters, we can add detail to the model to more completely match the observed velocities. We compare the models to the Hubble Space Telescope long-slit spectra of the Seyfert galaxies NGC 1068 and NGC 4151 in an effort to more fully understand the actual outflow mechanism of these galaxies.Drake University, Department of Physics and Astronom