A Simple Spectroscopic Technique To Identify Rejuvenating Galaxies
- Author
- Zhang, Junyu
- Published
- [University Park, Pennsylvania] : Pennsylvania State University, 2022.
- Physical Description
- 1 electronic document
- Additional Creators
- Leja, Joel and Schreyer Honors College
Access Online
- honors.libraries.psu.edu , Connect to this object online.
- Restrictions on Access
- Open Access.
- Summary
- Rejuvenating galaxies are unusual galaxies that fully quench and then subsequently experience a "rejuvenation" event to become star-forming once more. Such galaxies are relatively common in models of galaxy formation, where between 10%-70% of massive z = 0 galaxies are expected to experience a rejuvenation event. Observationally, the relative occurrence of rejuvenating systems is crucial for calibrating the strength of star formation feedback mechanisms in models. However, these predictions are challenging to test because rejuvenating systems blend in with normal star-forming galaxies in broadband photometry. In this paper, we use the galaxy spectral energy distribution (SED)-fitting code Prospector to search for observational markers that can distinguish normal star-forming galaxies from rejuvenating galaxies. We find that rejuvenating galaxies have smaller Balmer absorption line equivalent widths (EWs) than normal star-forming galaxies. This is analogous to the well-known "K + A" or post-starburst systems, which have strong Balmer absorption due to A-stars dominating the light: in this case, rejuvenating systems have a corresponding lack of A-stars, instead resembling "O - A" systems. We find star-forming galaxies that have H[beta], H[gamma], and/or H[delta] absorption EWs ≲ 3 ̊A correspond to a highly pure selection of rejuvenating systems. Interestingly, while this technique is highly effective at identifying systems undergoing mild rejuvenation, "strongly" rejuvenating systems remain nearly indistinguishable from star-forming galaxies due to the well-known stellar outshining effect. We conclude that measuring Balmer absorption line EWs in star-forming galaxy populations is an efficient method to identify rejuvenating populations, and discuss several techniques to either remove or resolve the nebular emission which typically lies on top of these absorption lines.
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- Genre(s)
- Dissertation Note
- B.S. Pennsylvania State University 2022.
- Technical Details
- The full text of the dissertation is available as an Adobe Acrobat .pdf file ; Adobe Acrobat Reader required to view the file.
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