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Where stars are born: Kinematics and photometry of starburst and postburst galaxies
Stockholm University, Faculty of Science, Department of Astronomy.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The understanding of the formation and evolution of galaxies will not be complete until we understand the physical processes that trigger and regulate starformation in them. This work is about star formation on several size scales. It includes the kinematic study of 157 H II regions in the spiral galaxy M83, in order to test the relation, if any, between luminosity (L) and velocity dispersion(s), indicative of virialization. We found that there is no strong correlation between the mentioned variables, but only an upper envelope with a maximum luminosity for a given velocity dispersion. We demonstrated that this envelope has a slope that is strongly dependent on an accurate correction of instrumental broadening. Using our experience in H II regions, we moved to star formation at larger scales. Thus, the bulk of this thesis is on starburst galaxies and their evolutionary descendants, the postburst galaxies. A starburst is a galaxy that is suddenly creating large amounts of stars, at a rate that is not sustainable for long periods.We performed a kinematic study of a sample of 11 such objects, showing that they are, in general, not supported by rotation and that many of them are consistent with a recent merger which affected their morphology and kinematics.Furthermore, from Sloan Digital Sky Survey (SDSS) we extracted a robust sample of 1006 starbursts and 240 postbursts at redshift 0.010<z<0.083. We performed a comparative study of their structural parameters, such as effective radius, sersic index, asymmetry and absolute magnitude. We have found that the majority of starbursts and postbursts in the nearby Universe are disky galaxies, with a tendency for starbursts to have shorter effective radii and larger asymmetries.

Place, publisher, year, edition, pages
Department of Astronomy, Stockholm University , 2012. , 66 p.
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Astronomy
Identifiers
URN: urn:nbn:se:su:diva-76454ISBN: 978-91-7447-531-9 (print)OAI: oai:DiVA.org:su-76454DiVA: diva2:526729
Public defence
2012-06-13, sal FB52, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 14:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 2: Manuscript; Paper 3: Manuscript.Available from: 2012-05-22 Created: 2012-05-14 Last updated: 2012-05-15Bibliographically approved
List of papers
1. An improved method for statistical studies of the internal kinematics of H ii regions: the case of M83
Open this publication in new window or tab >>An improved method for statistical studies of the internal kinematics of H ii regions: the case of M83
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2010 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 407, no 4, 2519-2529 p.Article in journal (Refereed) Published
Abstract [en]

We present the integrated H alpha emission line profile for 157 H ii regions in the central 3.4 x 3.4 arcmin2 of the galaxy M83 (NGC 5236). Using the Fabry-Perot interferometer GH alpha FaS, on the 4.2-m William Herschel Telescope on La Palma, we show the importance of a good characterization of the instrumental response function for the study of line profile shapes. The luminosity-velocity dispersion relation is also studied, and in the log(L)-log(Sigma) plane we do not find a linear relation, but an upper envelope with equation log(L-H alpha) = 0.9 log(Sigma) + 38.1. For the adopted distance of 4.5 Mpc, the upper envelope appears at the luminosity L = 1038.5 erg s-1, in full agreement with previous studies of other galaxies, reinforcing the idea of using H ii regions as standard candles.

Keyword
instrumentation: interferometers, methods: data analysis, H ii regions, galaxies: individual: M83, NGC 5236, galaxies: stellar content
National Category
Natural Sciences
Identifiers
urn:nbn:se:su:diva-50317 (URN)10.1111/j.1365-2966.2010.17078.x (DOI)000281948100037 ()
Note
authorCount :11Available from: 2010-12-22 Created: 2010-12-22 Last updated: 2017-12-11Bibliographically approved
2. Halpha kinematics of 11 starburst galaxies selected from the Sloan Digital Sky Survey
Open this publication in new window or tab >>Halpha kinematics of 11 starburst galaxies selected from the Sloan Digital Sky Survey
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2012 (English)Manuscript (preprint) (Other academic)
Abstract [en]

We present analysis of Fabry-Perot interferometric observations for a sample of 11starburst galaxies with redshift z . 0.03 selected from the Sloan Digital Sky Survey.We have targeted the H 6562.78 emission line at spatial sampling of 0.002−0.004 andat spectral resolution of R 16000, and studying two-dimensional velocity, velocitydispersion, line emission and continuum maps deliver new insights into the nature ofstarburst and postburst galaxies. The velocity fields are fitted to an exponential discmodel, providing scale lengths and masses, to be compared with the photometric scalelength and the mass estimated from the velocity dispersions. From the line emissionthe star formation rates are also calculated and compared with values in the literature.We have found that between 55% and 64% of our sample show large scale dominatingrotation, while 27% show local rotation typically restricted to the central part of eachsystem. The morphology and line profiles in the centre of eight objects are consistentwith a recent merger, while another two seem to be involved in a accretion processwhich has not disrupted their kin

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-76446 (URN)
Available from: 2012-05-15 Created: 2012-05-14 Last updated: 2012-05-15Bibliographically approved
3. Structural parameters of starburst and postburst galaxies
Open this publication in new window or tab >>Structural parameters of starburst and postburst galaxies
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2012 (English)Manuscript (preprint) (Other academic)
Abstract [en]

We present two samples of 1173 starbursts and 145 postburst in the redshift range0.01 < z < 0.083, selected from Sloan Digital Sky Survey Data Release 7. We charac-terize both samples using 2D Sersic profiles and measure their asymmetry. The Sersicindex, n, and the effective radii show that starburst galaxies are more concentratedthan the postburst sample, with median n 1.85 for starbursts and 2.85 for post-bursts. There is a large fraction of disky (n < 2) postbursts, a fraction larger thanreported by previous studies. Part of the excess comes from low luminosity (Mr > −19)objects, vastly dominated by discs. We estimate the mass from the velocity dispersionof the H emission line, both for the starbursts and those postbursts with residualemission, finding that Lr / Mb, with b = 1.35 for starbursts and b = 1.5 for post-bursts. The typical values of the mass-to-light ratio range between 0 and 10. This,now, is surprising for starburst galaxies, for which mass-to-light ratios 1 have beenpreviously found.

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-76448 (URN)
Available from: 2012-05-15 Created: 2012-05-14 Last updated: 2012-05-15Bibliographically approved
4.
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