University of Oulu

2D spectroscopy in astronomy

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Author: Rautiainen, Joona1
Organizations: 1University of Oulu, Faculty of Science, Physics
Format: ebook
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 5.7 MB)
Pages: 46
Persistent link: http://urn.fi/URN:NBN:fi:oulu-201905282219
Language: English
Published: Oulu : J. Rautiainen, 2019
Publish Date: 2019-06-04
Thesis type: Bachelor's thesis
Description:

Abstract

2D-spectroscopy in astronomy is defined as a technique where a spatially resolved electromagnetic spectrum is obtained over a two-dimensional field. In this paper the very basic principles of spectroscopy are briefly covered starting from the single slit concept via the Huygens principle and the Fraunhofer diffraction. The basic concept of a grating-based spectrograph is described. The connection between observed spectra, the chemical footprints and the underlying physical properties of the systems are briefly covered. The main IFU techniques used in the field of integral field spectroscopy are introduced. The basic ideas on how the data from the observed targets are produced and the wanted physical properties from the data are recovered are discussed. The work demonstrates the usage of 2D-spectroscopic data and its usefulness. The decay in the velocity dispersion profiles in the near central regions of galaxies known as sigma-drop is briefly introduced and a sample of 13 galaxies hosting a possible sigma-drop is analyzed via elliptical apertures. The radial profiles of each galaxy are extracted from given 2D-data connected to the kinematics of the sample galaxies. The radial profiles are then graphically presented with kinematic maps corresponding to the rotation velocity, the velocity dispersion, h₄ and h₃ profiles of the galaxy. Here the h₄ and h₃ are the amplitudes of the Gauss-Hermite series corresponding to the symmetric and asymmetric deviation from a Gaussian. The sample consists of only barred galaxies which could indicate star formation caused sigma-drops due to the bar-driven inflow of the gas to the central regions of the galaxies. Well-defined dust lanes are seen in ~70% of the sample showing a possible relation between the dust and the sigma-drops. There is no direct connection observed between the sigma-drops and the sizes of the galaxies.

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Copyright information: © Joona Rautiainen, 2019. This publication is copyrighted. You may download, display and print it for your own personal use. Commercial use is prohibited.