I Congreso de Postgrado fcfm: ingeniería, ciencias e innovación

25 Santiago, 10 al 12 de agosto, 2022 A S T RONOM Í A 01 STUDYING THE VARIABILITY OF QUASARS AS A FUNCTION OF REST-FRAME WAVELENGTH Priyanjali Patel¹ , Paulina Lira¹ , Patricia Arévalo² ¹Departamento de Astronomía, Universidad de Chile, Casilla 36D, Santiago, Chile ²Instituto de Física y Astronomía, Universidad de Valparaíso, Gran Bretaña 1111, Valparaíso, Chile *Email: priya@das.uchile.cl ABSTRACT We present the study of the correlations between Active Galactic Nuclei (AGN) variability and rest-frame wavelength. We study a sample of optical light curves from the Zwicky Transient Facility Data Release 6 for Active Galactic Nuclei (AGN) in the r-band (6339.61 Å) and the g-band (4722.74 Å). We use homogeneous analysis of SDSS DR14 quasars by Rakshit et al.(2020) to define a sample with well-measured Black Hole mass (MBH) and Eddington ratio/accretion rate (Ṁ) in a well-defined redshift bin. Our sample sources have 0.1 ≲ redshift ≲ 0.8, and 10^8.0 ≲ MBH/M☉ ≲ 10^8.5, while the Eddington ratio range is between 10^(-1.3) and 10^(-0.8). This sample was selected because the emission from quasars is highly variable, and variability is a potential key to understanding the accretion process. To prevent biases from redshift effects as time dilation, the light curves were corrected. Then we calculate the amplitude of variability (or variance) at different time scales in the power spectrum using the ‘Mexican-Hat’ filter (Arévalo et al., 2012) for 3429 sources in the g-band and 3897 sources in the r- band. Redshift is used as a tool to study different rest-frame wavelengths. In this work, we study variance on 300 and 75-day timescales and find a strong anti-correlation between rest-frame wavelengths andmedian variance. This anti-correlation suggests that optical fluctuations in short and long timescales are less in the outer annuli than in the inner annuli if rest-frame wavelength represents the accretion disk’s radius. We compare our result with the Corona-heated Accretion-disk Reprocessing (CHAR) Model (Sun et al., 2020) to predict the changes in variation with rest-frame wavelengths to understand the mechanism behind such variation. The slope of our result is similar to the one from the CHAR model with 1-sigma precision. ACKNOWLEDGMENT We are grateful to Dr. Mouyuan Sun for simulating ZTF light curves using CHAR model which helped to compare the result from the ZTF data to the one from the CHAR model paper. We also thank Santiago Bernal for providing code for the spectral fitting. We acknowledge support from ANID grant number 11100449. REFERENCES [1] Rakshit, S., Stalin, C. S. & Kotilainen, J. Spectral Properties of Quasars from Sloan Digital Sky Survey Data Release 14: The Catalog. Astrophys.J. Suppl. Ser. 249, 17 (2020) [2] Arévalo, P., Churazov, E., Zhuravleva, I., Hernández-Monteagudo, C. & Revnivtsev, M. A Mexican hat with holes: calculating low-resolution power spectra from data with gaps. Mon. Not. R. Astron. Soc. 426, 1793–1807 (2012). [3] Mouyuan Sun et al 2020. Corona-heated Accretion-disk Reprocessing: A Physical Model to Decipher the Melody of AGN UV/Optical Twinkling. ApJ 891, 178 (2020)