College of Science

Seminar: Rosalie McGurk [Carnegie Observatories]

Searching for Close Pairs of Active Black Holes by Combining Chandra Observations, Near-Infrared Imaging, and Optical Integral Field Spectroscopy

Oct 4, 2018 11:00 AM to Oct 4, 2018 12:00 PM at Building 8 - Room 241

When galaxies merge, gas accretes onto both central supermassive black holes, allowing us to see them as active black holes in the nuclei of galaxies. Thus, one expects to see close pairs of active galactic nuclei (AGNs), or dual AGNs, in a fraction of galaxy mergers. However, finding them remains a challenge. We studied a sample of double-peaked SDSS [O III] AGNs using Keck Laser Guide Star Adaptive Optics assisted imaging to find that 30% of double-peaked Sloan Digitial Sky Survey AGNs have two spatial components within a 3" radius. Unfortunately, the identity of the companion object is not revealed with imaging; X-ray observations can confirm these galaxy pairs as systems containing two AGNs. We performed Chandra X-ray ACIS-S observations on 12 double-peaked candidate dual AGNs with a possible near-infrared companion 1-3" away. While our X-ray observations confirm several dual AGNs among our sample, the rest of the candidates are too faint to be observed with Chandra. The candidates are more easily observed with optical spectroscopy, but to confirm these candidates we need more spatial information than is provided by long-slit spectroscopy. Integral field spectroscopy delivers spatially-resolved spectra over a large area, so we are building a new add-on to the IMACS spectrograph on the Magellan Telescope to enable its use as an integral field spectrograph. By assessing what fraction of double-peaked emission line SDSS AGNs are true dual AGNs, we can better determine whether double-peaked [O III] is an efficient dual AGN indicator and constrain the statistics of dual AGNs.

10:50 a.m. Refreshments

11:00 a.m. Seminar

Building 8 - Room 241

For further information, please call (909) 869-4014