Naadiyah Jagga

Ph.D. Candidate in Astrophysics

Home Research CV

Research projects

How well can we determine the stellar masses of galaxies?

Supervisors: Prof. dr. Henk Hoekstra & Dr. Alessandro Sonnenfeld

2020 - 2021

The stellar mass estimates of galaxies are key to e.g. the comparisons of observational parameters to predictions from cosmological simulations. Stellar masses are influenced by different parameters of the galaxy such as the star formation history, metallicity, time since star formation, and optical depth. We can find these parameters from multi-band observations by using broad-band spectral energy distribution fitting. We applied stellar population synthesis (BC03) to model spectra and studied the bias for an exponential star formation history model. The main interest of the research was if there are systematic uncertainties in the stellar mass when galaxies are split by color because other studies often compare astronomical parameters for blue and red galaxies such as the halo mass.

Link to stellar mass fitting code written by Alessandro Sonnenfeld: github.

Previous research on Jupiter's internal structure: Conroy (2013).

Stellar population synthesis with BC03: Bruzual & Charlot (2003).

Internal structure of Jupiter and Saturn: comparison of different equations of state for dense water

Supervisor: Dr. Yamila Miguel

2019 - 2020

A significant amount of heavy elements is expected in the core and small fractions in the interior of Jupiter and Saturn. The distribution of heavy elements in their interior are important to understand their formation history. We aimed to study the differences between equations of state of ice and their differences when applied to the interior models of Jupiter and Saturn. Within a temperature-density range that includes all (exo)planets the pressure and entropy are computed and showed that differences in the entropy values between the equations were more prevalent at higher temperatures. CEPAM is used to create planetary models and matches the equation of state to observational constraints. Temperature profiles revealed differences between the equations and this resulted in significant differences in the core mass predictions and the heavy elements abundance in the deep envelope for Jupiter and Saturn. Yet an accurate examination of the entropy calculation and the assumptions for the models is recommended before confirming these effects.

Ab initio equation of state of dense water: Mazevet et al. (2019).

Previous research on Jupiter's internal structure: Miguel et al. (2016).

Planetary modeling with CEPAM: Guillot & Morel (1995).

Difference imaging in MASCARA

Supervisor: Prof. dr. Ignas Snellen

February 2019 - June 2019

Difference imaging is introduced to MASCARA to test the ability of image subtraction for MASCARA observations. Since the MASCARA stations cover together the near-entire sky, and the stars in MASCARA observations remain in a pixel in one integration, variable sources could be detected using difference imaging. We aimed to search for variable sources in the sky, and to identify which type of sources are detectable with MASCARA. By performing image subtraction with help of ISIS and PSF photometry to obtain light curves 5 variable stars, 5 non-variable stars, and 4 unidentified targets are found in a small box of sky. The light curves have an uncertainty of approximately 3%. The identified variable sources were eclipsing and pulsating variable stars. Some light curves showed behaviour of variables but are not known as variable objects. Nevertheless, the period of the used data set is too short to report those stars as variables, hence, analysis over a larger box of sky and a longer time period will identify more variable sources.

Variable stars in MASCARA: Burggraaff et al. (2018).

The working of MASCARA: Talens et al. (2017).

Difference imaging with ISIS: Alard et al. (1998).