Tracing the Inner Galactic Halo with Blue Horizontal Branch Stars Using Spectrophotometry from Gaia Data Release 3

Zwerver, Annemarijn (2023) Tracing the Inner Galactic Halo with Blue Horizontal Branch Stars Using Spectrophotometry from Gaia Data Release 3. Bachelor's Thesis, Astronomy.

Preview	Text bAST_2023_ZwerverA.pdf Download (8MB) | Preview
	Text toestemming.pdf Restricted to Registered users only Download (129kB)

Abstract

In this thesis we draw synthetic photometry from novel low-resolution spectra provided by Gaia Data Release 3 to discriminate blue horizontal branch stars from the contamination population of blue stragglers. We investigate the use of several filter combinations and use synthetic Pristine CaHK and synthetic SDSS ugr photometry to create an all-sky sample of blue horizontal branch star candidates with a purity of 99% and a completeness of 75%. To pick-up fainter magnitudes, we use SDSS DR18 ugr photometry in combination with synthetic Pristine CaHK photometry, improving the completeness to 81%, but limiting us to the SDSS footprint. We also investigate the use of J-PAS 4200 photometry to compensate for the relatively large uncertainties in CaHK and suggest follow-up. We subsequently use these samples of standard candles to create 3D maps of the inner halo of the Milky Way and investigate spatial overlap with stellar streams, including the Sagittarius stream. With the currently available XP spectra of roughly 200 million stars we are restricted to 17.65 mag, but we foresee large potential in future Gaia releases, where the XP spectra of 2 billion sources (down to 20.5 mag) will become available, and by applying the methods we present in this thesis we might be able to significantly increase the number of BHB candidates, as well as mapping the halo out to distances of 100 kpc.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Starkenburg, E.
Degree programme:	Astronomy
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	27 Jul 2023 14:20
Last Modified:	04 Sep 2023 13:52
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/30209

Actions (login required)

View Item