Revisiting The Radio Dichotomy of Quasars

Wortelboer, Mariëlle (2023) Revisiting The Radio Dichotomy of Quasars. Bachelor's Thesis, Astronomy.

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Abstract

This thesis revisits the debate about the radio-loudness dichotomy by separating the total luminosity in the radio and optical bands into two components: star formation (SF) and active galactic nuclei (AGN). Afterward, the obtained distribution is examined as a function of quasar properties. The parameter used for the radio-loudness is given as $\mathcal{R} = L_\text{144 MHz}/L_i$. I used the SDSS DR16 Quasar catalog and cross-matched it to radio data from LOFAR, far-infrared data from Herschel, ancillary x-ray data from eROSITA and Chandra, and mid-infrared data from WISE. With the cross-matched data, SEDs were modeled by a multi-wavelength SED fitting code: CIGALE. The SEDs provided AGN fractions to separate the SF in the i-band. The LOFAR 144 MHz luminosity was separated by converting the total infrared dust luminosity, obtained by CIGALE, into 144 MHz radio luminosity. This was done using the far-infrared radio correlation (FIRC). The result was subtracted from the total. The separated distribution of $\mathcal{R}$ shows a slight bump which might hint at a potential dichotomy. However, no obvious bimodality was found. Quasar properties portray weak to no dependencies on $\mathcal{R}$. Although weak, the different correlations could indicate that radio-loudness is a quasar property that changes with the evolution of quasars.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Wang, L.
Degree programme:	Astronomy
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	12 Jul 2023 09:13
Last Modified:	12 Jul 2023 09:13
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/30551

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