Radio continuum in HI-selected galaxies from the Apertif surveys

Ussia, Giuseppe (2023) Radio continuum in HI-selected galaxies from the Apertif surveys. Master's Thesis / Essay, Astronomy.

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Abstract

I present a comparative analysis of star formation rate (SFR) tracers, at different electromagnetic bands, in a sample of HI-selected galaxies taken from Apertif HI survey. In addition to the presence of atomic gas, I require them to also have a radio continuum (RC) counterpart, performing a cross match with the Apertif DR1 catalog. I get their corresponding infrared (IR) data from WISE survey and I later use information with improved extended source photometry (T. Jarrett, priv. comm.). The purpose of this study is to explore the consistency of SF tracers at different bands, test the far-IR-Radio correlation and see how well radio continuum works as a SF tracer in dwarf galaxy regimes. I performed a visual inspection procedure, aimed at identifying possible AGN contaminations that often occur in the radio band. As a result, I created a subsample of galaxies having a good match of RC contours with the shape of the source as seen in WISE W1 photometry. Then, I investigated the relations of SFRs at different IR bands with the RC based one. Finally, I performed a further comparison with the far-ultraviolet (FUV) SFR tracer derived from GALEX data. The trends between the WISE W3 (12μm) and W4 (22μm) band derived SFRs and the RC SFRs are relatively tight linear relations. However, when using the mid-IR SF tracer, derived from a combination of W3 and W4, including a correction calibrated from galaxies with FUV data to account for the typical low dust content of smaller galaxies, the IR SFR vs RC SFR trend clearly deviates from a one-to-one line, with a discrepancy at small values. The final FUV test has not confirmed the reliability of the RC or IR tracers at lower SFR values. Therefore, further investigations are advisable, for example using improved Apertif data products and a more dwarf-dominated sample.

Item Type:	Thesis (Master's Thesis / Essay)
Supervisor name:	Adams, E.A.K.
Degree programme:	Astronomy
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	30 Jun 2023 12:10
Last Modified:	23 Jan 2024 14:56
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/30183

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