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Examining variable galactic nuclei with the help of astronomical databases and archives
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
2019 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

There exists many astronomical objects that vary in brightness. Objects such as variable stars like the Cepheids that periodically expands and contracts their outer layers, or the active galactic nuclei (AGN) where accretion of matter into a black hole generates a often varying brightness. Several candidates for being such variable objects have been identified as a result of the Vanishing and Appearing Stuff during a Century of Observations (VASCO) project. These candidates were then narrowed down to a handful that showed variability towards the infrared part of the spectrum. This bachelor’s thesis then aims to look further into these candidates using various databases and catalogues taking data from several sky surveys (SDSS, 2MASS etc). This is done to get better overview of the objects lightcurve over a bigger part of the spectrum, to establish whether the variability is real or a result from errors and to form a hypothesis of what kind of objects they could be. The result obtained from the data from the surveys points towards all the objects being real variable objects. The hypothesis is that all the objects are AGN’s that vary in brightness.

Abstract [sv]

Det existerar många olika astronomiska objekt som varierar i ljusstyrka. Allt från variabla stjärnor som Cepheiderna som periodvis expanderar och kontraherar dess yttre skikt, till aktiva galaxkärnor där ackretion av materia in i ett svart hål genererar en ofta varierande ljusstyrka. Ett flertal kandidater för just sådana varierande objekt har identifierats som ett resultat av VASCO projektet. Dessa kandidater har sedan skalats ner till en handfull mängd kandidater som visade variation mot den infraröda delen av spektrumet. Detta kandidatarbete siktar på att vidare undersöka dessa kandidater genom att använda diverse astronomiska databaser och kataloger för att få data från flera kartläggningsprojekt (t.ex. SDSS, 2MASS etc). Detta är gjort för att få en bättre överblick över objektens ljuskurvor över en större del av spektrumet, att fastställa ifall objekten är riktiga variabla objekt eller uppstått på grund av diverse fel, samt att framställa en hypotes för vad det är för typ av objekt de kan vara. Resultaten från undersökningarna pekar på att alla objekten är riktiga variabla objekt. Hypotesen är att alla av objekten är aktiva galaxkärnor som varierar i ljusstyrka.

Place, publisher, year, edition, pages
2019. , p. 33
Series
FYSAST ; FYSKAND1109
Keywords [en]
Active Galactic Nuclei, Variable stars, Variable objects
Keywords [sv]
Aktiva Galaxkärnor, Variabla stjärnor, Variabla objekt
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:uu:diva-389348OAI: oai:DiVA.org:uu-389348DiVA, id: diva2:1336652
Educational program
Bachelor Programme in Physics
Supervisors
Examiners
Available from: 2019-07-11 Created: 2019-07-10 Last updated: 2019-07-11Bibliographically approved

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CiteExportLink to record
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