Universität zu Köln

Steiniger, Lukas ORCID: 0000-0002-5859-3932 (2023). Linking Star Formation and Black Hole Mass Growth in External Galaxies. PhD thesis, Universität zu Köln.

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Abstract

Active galactic nuclei (AGNs) count among the most extreme phenomena in astrophysics. An AGN lies at the center of an active galaxy and at the heart of an AGN lies in turn a supermassive black hole (SMBH). Multiple connections have been found between the central SMBH and the bulge of its host galaxy. A co-evolution is implied from this, as a bulge is typically more massive than the SMBH at its center by virtually always more than a factor of 100. Some objects from the so-called low-luminosity type-1 quasi-stellar object (LLQSO) sample have been analyzed with respect to black hole mass - bulge luminosity relations for inactive galaxies. It was found that LLQSOs deviate from these relations either due to undermassive SMBHs or overluminous bulges. The latter is a more likely explanation, as there are signs for star formation in the bulges. This work increases the previous sample size by almost a factor of 2 and examines findings in the context of the overall larger sample. The additional LLQSOs were observed in two epochs in 2019, utilizing the New Technology Telescope equipped with the near-infrared instrument SOFI. Bulge magnitudes as substitutes for the luminosities are found from K-band imaging, while long-slit spectroscopy, covering roughly the H- and K-band, enables the identification of diagnostic lines and SMBH mass estimates. The addition of the new LLQSOs to the previously analyzed objects within the same diagram reveals a similar scatter for both samples. LLQSOs lie on average below the suggested literature relations for inactive galaxies, strengthening previous findings significantly. Furthermore, the new LLQSOs also show signs for star formation based on spectral features that originate from molecular gas. The results support a scenario, in which star formation precedes the growth of the SMBH. This matches the idea of a trajectory of LLQSOs in the diagram, that first shifts these objects away from literature relations and subsequently back towards these.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Steiniger, Lukas lukas.d.steiniger@gmail.com orcid.org/0000-0002-5859-3932 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-708021
Date:	2023
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute of Physics I
Subjects:	Physics
Uncontrolled Keywords:	Keywords Language Astrophysics, Black Holes, Galaxies, Active Galactic Nuclei, Near-Infrared English
Date of oral exam:	19 July 2023
Referee:	Name Academic Title Eckart, Andreas Prof. Dr. Zensus, J. Anton Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/70802