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X-ray emission from supernova shock waves
Stockholm University, Faculty of Science, Department of Astronomy.
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A theoretical study of the interaction between supernovae and their surroundings is presented.

Supernovae are the endpoint of the life of massive stars, and are the dominant contributors to the chemical evolution of the Universe. During its life a massive star greatly modifies its environment. During and after the explosion of the star it interacts with its surroundings in a number of ways. A study of this interaction yields invaluable information about the late stages of stellar evolution and the physics of supernova explosions. Recent advances in observational facilities have given a wealth of observational data on interacting supernovae, and it is therefore essential to have good theoretical models for interpreting the data.

This thesis presents an overview of the physics of supernovae and of their interaction with a circumstellar medium. In particular the reverse shock created by the interaction is investigated. In most Type IIL and Type IIn supernovae this shock is radiative, and due to the high temperature most of the radiation comes out as X-rays. A numerical model is presented which calculates the emission from the cooling region behind the reverse shock in a self-consistent way, by combining a hydrodynamic model with a time-dependent ionization balance and multilevel calculations. This has been applied to some of the best cases of circumstellar interaction.

As a further application of the model the radio and X-ray emission from Type IIP supernovae is discussed. We estimate the mass loss rate of the progenitors of Type IIP supernovae, and find that a superwind phase is not required.

VLT observations of the ring of SN 1987A show broad optical emission lines coming from a range of ionization stages, in particular optical coronal lines of Fe X-XIV. Models of the line emission indicate that the lines are formed by cooling shocks with shock velocities in the range 310-390 km/s, confirming the picture of shocks striking the protrusions from the ring obliquely.

X-ray observations of the Type IIb SN 1993J and Type IIn SN 1998S are analyzed. For SN 1993J we find that the spectrum is best fit with a CNO-enriched composition. For SN 1998S we find that the high metal overabundance that has previously been claimed, is not necessary when a self-consistent model of the cooling region is applied.

Place, publisher, year, edition, pages
Stockholm: Institutionen för astronomi , 2007. , 62 p.
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Astronomy
Identifiers
URN: urn:nbn:se:su:diva-6671ISBN: 91-7155-377-0 (print)OAI: oai:DiVA.org:su-6671DiVA: diva2:196851
Public defence
2007-03-20, sal FB53, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00
Opponent
Supervisors
Available from: 2007-02-27 Created: 2007-02-20 Last updated: 2012-08-27Bibliographically approved
List of papers
1. X-ray emission from radiative shocks in Type II supernovae
Open this publication in new window or tab >>X-ray emission from radiative shocks in Type II supernovae
2006 In: Astronomy and Astrophysics, ISSN 0004-6361, Vol. 449, no 1, 171-192 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-24138 (URN)
Note
Part of urn:nbn:se:su:diva-6671Available from: 2007-02-27 Created: 2007-02-20Bibliographically approved
2. Radio and X-ray emission as probes of Type IIP supernovae and red supergiant mass loss
Open this publication in new window or tab >>Radio and X-ray emission as probes of Type IIP supernovae and red supergiant mass loss
2006 In: Astrophysical Journal, ISSN 0004-637X, Vol. 641, 1029-1038 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-24139 (URN)
Note
Part of urn:nbn:se:su:diva-6671Available from: 2007-02-27 Created: 2007-02-20Bibliographically approved
3. Coronal emission from the shocked circumstellar ring of SN 1987A
Open this publication in new window or tab >>Coronal emission from the shocked circumstellar ring of SN 1987A
Show others...
2006 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 456, no 2, 581-589 p.Article in journal (Refereed) Published
Abstract [en]

High resolution spectra with UVES/VLT of SN 1987A from December 2000 until November 2005 show a number of high ionization lines from gas with velocities of ± 350 km s-1, emerging from the shocked gas formed by the ejecta-ring collision. These include coronal lines from [Fe X], [Fe XI] and [Fe XIV] which have increased by a factor of 20 during the observed period. The evolution of the lines is similar to that of the soft X-rays, indicating that they arise in the same component. The line ratios are consistent with those expected from radiative shocks with velocity 310{-}390 km s-1, corresponding to a shock temperature of (1.6{-}2.5)× 106 K. A fraction of the coronal emission may, however, originate in higher velocity adiabatic shocks.

Keyword
supernovae: individual: SN 1987A, circumstellar matter, shock waves
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-20166 (URN)10.1051/0004-6361:20065325 (DOI)
Available from: 2007-02-27 Created: 2007-02-27 Last updated: 2017-12-13Bibliographically approved
4. Modeling the X‐rays from SNe 1993J & 1998S
Open this publication in new window or tab >>Modeling the X‐rays from SNe 1993J & 1998S
2007 (English)In: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 937, no 430, 430-432 p.Article in journal (Refereed) Published
Abstract [en]

TheX-ray emission from the Type II supernovae SNe 1993J and1998S is modelled using the numerical code described in Nymarket al. (2006), assuming that most of the observed X-ray emissioncomes from the reverse shock created by the interaction betweenthe supernova ejecta and a dense circumstellar medium. We findthat the spectra of both SNe are compatible with aCNO-enriched composition. For SN 1998S we find evidence for acomponent from both the reverse and forward shock, while theX-ray flux for SN 1993J is dominated by the reverseshock.

Keyword
supernovae, X-ray emission spectra, circumstellar matter, shock waves
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-24141 (URN)10.1063/1.2803603 (DOI)978-0-7354-0448-9 (ISBN)
Available from: 2007-02-27 Created: 2007-02-20 Last updated: 2017-12-13Bibliographically approved

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