RSAA Colloquia / Seminars / Feast-of-Facts: Wednesday, 28 November 2018, 11:40-12:00; CSO Common Room

Umang Malik

"Simulating Lag Recovery for Low-Luminosity AGN with Reverberation Mapping"

The Australian Dark Energy Survey is entering the final year of a 6-year Reverberation Mapping program, to measure the mass of the central supermassive black holes of almost 800 Active Galactic Nuclei. Reverberation Mapping measures the time taken for continuum emission radiated from the core of AGN to ionise clouds of gas orbiting the central black hole. The ultimate goal is to develop the AGN as new “standardisable candles”, allowing us to determine distances in the Universe far beyond what is currently practical using supernovae. This would greatly improve our ability to understand dark energy and the evolution of the expansion of the Universe. We find that the current OzDES spectroscopic cadence (approximately monthly) poorly samples the emission-line light curves of the lower luminosity AGN at z < 1. This is a critical limitation as these sources anchor the calibration of high-z AGN as cosmological distance standards, and overlap with the region where type Ia supernova measurements are abundant, allowing cross-probe analysis.My analysis indicates that the window function for observational data plays a critical role in lag recovery, more so than the global number of data points, or the duration of the survey. This classic observational “quality verses quantity” problem can be ameliorated through stacking of observations from physically similar sources to recover statistical properties for this class of object.