Discovery of a new extreme changing-state quasar with 4 mag variation, SDSS J125809.31+351943.0

Abstract

We report the discovery of a quasar, SDSS J125809.31+351943.0 (J1258), which brightened in optical for 4 mag from 1983 to 2015, which is one of the largest quasar brightening events so far. The history of optical photometry data of this quasar from the Catalina Real-time Transient Survey and All Sky Automated Survey for Super Novae (ASAS-SN), mid-infrared photometry data from the WISE satellite, and the broad emission line (BEL) flux obtained by spectroscopy of Sloan Digital Sky Survey shows their significant increases between 2003 and 2015. Investigating its CFHT photometric observations in 1983 and the USNO-B catalog, which contains data in 1975 and 1969, we found that the source was 4 mag fainter before than the peak of the recent ASAS-SN photometry. From the history of these data, we identified J1258 as a new Changing-State Quasar (CSQ; or Changing-Look Quasar). We also performed follow-up spectroscopic observations in December 2018 and May 2019, using the 2-meter telescope in Nishi-Harima Astronomical Observatory. The results show that the continuum flux and the BEL flux decreased to about 50 % of its peak. This indicates that J1258 is causing two changing-states for the BEL flux and continuum flux. We argue that J1258's variability, especially its brightening event, can be explained by the propagation of the heating front and the accretion disk state transitions based on the timescale and Eddington ratio variations. The estimated mass of the black hole of J1258 is about an order of magnitude larger than the CSQs found so far. Since both the changing timescale and the size of the accretion disk depend on the black hole mass, the J1258 brightening event can be interpreted as a scaled version of the variability in other CSQs. This suggests that samples of distant quasars with larger black hole masses may contain objects with longer and severer variations.

10 pages, 10 figures, accepted in Publications of the Astronomical Society of Japan

References in corpus (9)

• The 2.5 m Telescope of the Sloan Digital Sky Survey
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• Initial Performance of the NEOWISE Reactivation Mission
• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• Accretion disc viscosity: how big is alpha?
• The Discovery of the First "Changing Look" Quasar: New Insights into the Physics & Phenomenology of AGN
• iPTF Discovery of the Rapid "Turn On" of a Luminous Quasar
• The Close AGN Reference Survey (CARS) - What is causing Mrk1018's return to the shadows after 30 years?
• Polarization of the changing-look quasar J1011+5442

Cited by in corpus (4)

• The Time Domain Spectroscopic Survey: Changing-Look Quasar Candidates from Multi-Epoch Spectroscopy in SDSS-IV
• Exploring Changing-look Active Galactic Nuclei with the Sloan Digital Sky Survey V: First Year Results
• Discovering vanishing objects in POSS I red images using the Virtual Observatory
• The relation between quasars' optical spectra and variability