Searching for binary and dual supermassive black holes in large surveys

The observed structure of the universe suggests that galaxy mergers and the co-evolution of their central supermassive black holes (SMBHs) are common throughout the cosmos. While the formation of binary SMBHs seems inevitable, direct observational evidence of binary SMBHs has been elusive. No gravitational wave has yet been detected from the coalescence of a binary SMBH in the local universe. Evolution of binary SMBHs from kilo-parsec to sub-parsec scales and their interactions with host galaxies are still not well understood. Active SMBHs, known as quasars, provide an excellent way to study distant SMBHs in electromagnetic waves. A census of dual and binary quasars in different scales remains an essential puzzle in many aspects of astronomy. This dissertation consists of several studies aimed at searching for dual and binary quasars on different scales, from kiloparsec to milli-parsec. Chapter 2 focuses on discovering kilo-parsec dual quasar candidates using a novel astrometric technique. Chapter 3 presents a case study of a confirmed kiloparsec dual quasar in a galaxy merger at a redshift of 2.17. In Chapter 4, the focus shifts to the search for dual/offset quasar candidates with parsec-scale separations. Chapter 5 presents a systematic search of periodic quasars, which are thought to be sub-parsec binary SMBHs, using optical light curves. Chapter 6 investigates the precessing jet scenario for three periodic quasar candidates discovered in Chapter 5. This thesis paves the way for discovering dual and binary quasars using various methods and provides implications for future telescopes and surveys.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Astronomy

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Chen, Yu-Ching

Contributors dc:contributor

• Liu, Xin
• Gammie, Charles F
• Shen, Yue
• French, Decker K

• Active Galaxies
• Quasars
• Binaries, Galaxy Evolution
• Surveys

Statement dc:rights

• Copyright 2023 Yu-Ching (Tony) Chen

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/121390

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F121390