A Comprehensive Study of AGN Optical Variability from Minute to Decade Time Scales

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

This project will comprehensively investigate the variation of radiation emitted from supermassive black holes that are actively accreting matter. Almost all galaxies harbor a supermassive black hole at their centers, and their active galactic nuclei (AGN) emit an enormous amount of energy, which can surpass that of all the stars in the galaxy. AGN radiation is varying over time, and this variability is random or stochastic, which encodes important AGN accretion physics. The team will analyze the dataset from two surveys: the All-Sky Automated Survey for Supernovae (ASAS-SN) and the Transiting Exoplanet Survey Satellite (TESS). The combined datasets will allow the team to study AGN variability in the optical band from minutes to decade time scales, spanning five orders of magnitude in frequency. The AGN sample of this project is approaching 10,000, significantly larger than previous studies. Combining with other surveys in the X-ray band, the team will measure the correlated variability characteristics of AGN between optical and X-ray bands. The team will also train a graduate student and several undergraduate students. In addition, the team will further enrich a portable planetarium program for K-12 schools in central Oklahoma. These activities will impact 1,200 K-12 students annually, engage participants of the proposed educational programs in quality learning experiences that strengthen their STEM content knowledge, and inspire the next generation of students to pursue and excel in STEM careers. ASAS-SN is a network of small telescopes distributed around the globe to provide daily, all-sky monitoring of celestial objects brighter than 18th magnitude. ASAS-SN has accumulated 10 years of monitoring data, and this enables AGN variability studies in the optical band for a large sample of bright AGN. These bright AGN will also be monitored from space by TESS in short time-scales with 10–30 minute cadences. The combined ASAS-SN and TESS data will allow AGN optical variability study in five orders of magnitude in the frequency space, probing minute to decade timescales. The combination of ASAS-SN, TESS, Swift, and RXTE surveys provide a unique data set to jointly study optical and X-ray variability of bright AGN. This project is jointly funded by MPS/Division of Astronomical Sciences (AST) and the Established Program to Stimulate Competitive Research (EPSCoR). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.