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Exploring the diversity in hydrogen-deficient supernovae [Elektronische Ressource] / Stefan Taubenberger

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Published 01 January 2008
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Technische Universit¨at Mu¨nchen
Max-Planck-Institut fu¨r Astrophysik
Exploring the Diversity
in
Hydrogen-Deficient Supernovae
Stefan Taubenberger
Vollsta¨ndiger Abdruck der von der Fakult¨at fu¨r Physik der Technischen Uni-
versit¨at Mu¨nchen zur Erlangung des akademischen Grades eines
Doktors der Naturwissenschaften (Dr. rer. nat.)
genehmigten Dissertation.
Vorsitzender: Univ.-Prof. Dr. L. Oberauer
Pru¨fer der Dissertation:
1. Hon.-Prof. Dr. W. Hillebrandt
2. Univ.-Prof. Dr. R. Kru¨cken
DieDissertationwurdeam22.2.2008beiderTechnischenUniversit¨atMu¨nchen
eingereicht und durch die Fakulta¨t fu¨r Physik am 11.4.2008 angenommen.Contents
1 Introduction 9
1.1 Historical overview and SN classification . . . . . . . . . . . . . 10
1.2 Thermonuclear supernovae . . . . . . . . . . . . . . . . . . . . . 16
1.2.1 Explosion mechanisms . . . . . . . . . . . . . . . . . . . 16
1.2.2 Observational facts . . . . . . . . . . . . . . . . . . . . . 20
1.2.3 SNe Ia as cosmological tools . . . . . . . . . . . . . . . . 21
1.2.4 Delay times . . . . . . . . . . . . . . . . . . . . . . . . . 25
1.2.5 Own work . . . . . . . . . . . . . . . . . . . . . . . . . . 26
1.3 Stripped-envelope core-collapse supernovae . . . . . . . . . . . . 27
1.3.1 Explosion mechanisms . . . . . . . . . . . . . . . . . . . 28
1.3.2 Observational facts . . . . . . . . . . . . . . . . . . . . . 30
1.3.3 The SN-GRB connection . . . . . . . . . . . . . . . . . . 31
1.3.4 Asphericity of the ejecta . . . . . . . . . . . . . . . . . . 33
1.3.5 Own work . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2 Data acquisition and processing 37
2.1 Data acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.2 Telescopes and instrumentation . . . . . . . . . . . . . . . . . . 38
2.3 Data reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.3.1 Pre-reduction . . . . . . . . . . . . . . . . . . . . . . . . 43
2.3.2 Photometry . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.3.3 Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . 52
Thermonuclear Supernovae 55
3 The European Supernova Collaboration 57
3.1 The concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
iiiiv CONTENTS
3.2 SNe studied by the ESC . . . . . . . . . . . . . . . . . . . . . . 58
3.3 Generic results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4 The underluminous Type Ia Supernova 2005bl 71
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.2 Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.3 Distance, extinction and host-galaxy properties. . . . . . . . . . 77
4.4 Photometric evolution . . . . . . . . . . . . . . . . . . . . . . . . 86
4.4.1 Filtered light curves . . . . . . . . . . . . . . . . . . . . . 86
4.4.2 Bolometric light curve. . . . . . . . . . . . . . . . . . . . 87
4.4.3 Colour evolution . . . . . . . . . . . . . . . . . . . . . . . 89
4.5 Spectroscopic evolution . . . . . . . . . . . . . . . . . . . . . . . 89
4.5.1 Spectra of SN 2005bl . . . . . . . . . . . . . . . . . . . . 89
4.5.2 Comparison with other underluminous SNe Ia . . . . . . 92
4.5.3 Ejecta velocities . . . . . . . . . . . . . . . . . . . . . . . 95
4.6 Spectral modelling . . . . . . . . . . . . . . . . . . . . . . . . . . 97
4.6.1 Concept of the radiative transfer code . . . . . . . . . . . 97
4.6.2 Model parameters & chemical composition . . . . . . . . 98
4.7 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
4.7.1 Photometric behaviour of underluminous SNe Ia . . . . . 101
4.7.2 The rise time of underluminous SNe Ia . . . . . . . . . . 107
4.7.3 Spectroscopic parameters . . . . . . . . . . . . . . . . . . 110
4.7.4 Element abundances from synthetic spectra . . . . . . . 114
4.8 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Stripped-envelope core-collapse Supernovae 121
5 SN 2004aw: Diversity in Type Ic Supernovae 123
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
5.2 Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
5.2.1 Photometric observations . . . . . . . . . . . . . . . . . . 126
5.2.2 Spectroscopic observations . . . . . . . . . . . . . . . . . 128
5.3 Distance and Extinction . . . . . . . . . . . . . . . . . . . . . . 128
5.4 Light curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
5.4.1 Optical light curves . . . . . . . . . . . . . . . . . . . . . 133
5.4.2 Near-IR light curves . . . . . . . . . . . . . . . . . . . . . 136
5.4.3 Colour evolution . . . . . . . . . . . . . . . . . . . . . . . 138
5.4.4 Absolute magnitudes, bolometric light curve . . . . . . . 139
5.5 Spectral evolution . . . . . . . . . . . . . . . . . . . . . . . . . . 141CONTENTS v
5.5.1 Sequence of optical spectra . . . . . . . . . . . . . . . . . 141
5.5.2 Comparison to optical spectra of other SNe Ic . . . . . . 143
5.5.3 Near-IR spectroscopy: Identification of Hei lines? . . . . 148
5.5.4 Ejecta velocities . . . . . . . . . . . . . . . . . . . . . . . 151
5.6 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
5.6.1 Search for an associated GRB . . . . . . . . . . . . . . . 156
5.6.2 Mass of the ejecta . . . . . . . . . . . . . . . . . . . . . . 157
5.7 Summary and Outlook . . . . . . . . . . . . . . . . . . . . . . . 159
6 Nebular line profiles of Type Ib/c SNe 161
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
6.2 The sample of SN Ibc spectra . . . . . . . . . . . . . . . . . . . 163
6.2.1 The full sample . . . . . . . . . . . . . . . . . . . . . . . 164
6.2.2 Previously unpublished spectra . . . . . . . . . . . . . . 164
6.3 Fitting the oxygen line . . . . . . . . . . . . . . . . . . . . . . . 169
6.3.1 Expected line profiles . . . . . . . . . . . . . . . . . . . . 169
6.3.2 [OI] λ6300 and [OI] λ6364 . . . . . . . . . . . . . . . . . 173
6.3.3 The fitting procedure . . . . . . . . . . . . . . . . . . . . 176
6.4 Blueshifted line centroids at early phases . . . . . . . . . . . . . 177
6.5 Statistical analysis, inferred ejecta geometries. . . . . . . . . . . 184
6.5.1 Taxonomy . . . . . . . . . . . . . . . . . . . . . . . . . . 184
6.5.2 Statistical evaluation . . . . . . . . . . . . . . . . . . . . 187
6.6 Discussion of individual objects . . . . . . . . . . . . . . . . . . 190
6.6.1 SNe 1994I, 1996N and 1996aq: blueshifted blobs? . . . . 190
6.6.2 SNe 1990B, 1993J and 2006ld: clumpy ejecta . . . . . . . 192
6.6.3 SNe 1998bw and 2002ap: narrow cores? . . . . . . . . . . 192
6.6.4 SNe 2003jd and 2006T: classical double peaks . . . . . . 193
6.6.5 SNe 2000ew and 2004gt: jet-events or ‘fake’ double peaks?194
6.6.6 SNe 1991N and 1997X: spherical explosions? . . . . . . . 195
6.7 The profile of Mgi] λ4571 . . . . . . . . . . . . . . . . . . . . . . 196
6.8 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
6.9 Appendix: fit parameters . . . . . . . . . . . . . . . . . . . . . . 201
7 Summary and outlook 207
Bibliography 213List of Tables
1.1 Historical Galactic supernovae during the past millennium. . . . 10
4.1 Properties of SN 2005bl and its host galaxy. . . . . . . . . . . . 75
4.2 BessellUBVRI andSloangriz magnitudesofthelocalsequence
stars in the field of SN 2005bl. . . . . . . . . . . . . . . . . . . . 76
4.3 S- and K-corrected Bessell magnitudes of SN 2005bl. . . . . . . 78
4.4 Amount of S- and K-correction contained in the magnitudes
reported in Table 4.3. . . . . . . . . . . . . . . . . . . . . . . . . 80
4.5 Sloan photometry of SN 2005bl. No S- and K-correction has
been applied. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.6 Journal of spectroscopic observations of SN 2005bl. . . . . . . . 82
4.7 Physical parameters of SN 2005bl inferred from synthetic spec-
tra. The mass fractions of selected elements are recorded, and
solar photospheric abundances are shown for comparison. . . . . 98
4.8 Comparison sample of SNe Ia with Δm (B) > 1.5 – dis-15 true
tances and colour excesses. . . . . . . . . . . . . . . . . . . . . . 103
4.9 ComparisonsampleofSNeIawithΔm (B) >1.5–intrinsic15 true
properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
5.1 Magnitudes of local sequence stars in the field of SN 2004aw. . . 127
5.2 IR photometry of SN 2004aw. . . . . . . . . . . . . . . . . . . . 128
5.3 Optical photometry of SN 2004aw. . . . . . . . . . . . . . . . . . 129
5.4 Spectroscopic observations of SN 2004aw. . . . . . . . . . . . . . 131
5.5 Main photometric parameters of SN 2004aw. . . . . . . . . . . . 135
5.6 Comparison of absolute magnitudes, kinetic energy, ejecta mass
and Ni mass of SNe Ic. . . . . . . . . . . . . . . . . . . . . . . . . 158
6.1 List of SNe Ib/c studied in this paper. . . . . . . . . . . . . . . . 165
6.2 Instrumental details of previously unpublished spectra. . . . . . 168
12 LIST OF TABLES
6.3 Selected ejecta geometries and corresponding line profiles. . . . . 186
6.4 SN taxonomy in terms of [Oi] line profiles. . . . . . . . . . . . . 187
6.5 Parameters of the best one-component (cols. 4–6) and two-
component (cols. 7–13) fits of [Oi] λ6300. . . . . . . . . . . . . . 202
6.6 Parameters of the best three-component fits of the [Oi] λ6300
line for selected spectra with complex line profiles. . . . . . . . . 205List of Figures
1.1 Classical distinctioninto Type Ia, Ib, Icand Type IISNeon the
basis of representative spectra. . . . . . . . . . . . . . . . . . . . 12
1.2 Up-to-date SN classification scheme, with a number of recently
established subclasses added. . . . . . . . . . . . . . . . . . . . . 13
1.3 Formation of P-Cygni line profiles in expanding atmospheres.
Absoption and emission regions are indicated in the figure. . . . 14
1.4 Schematic light curves of different SN classes.. . . . . . . . . . . 16
1.5 Snapshots of a full 3D multi-spot-ignited simulation of a SN-
Ia deflagration. Rayleigh-Taylor instabilities (‘mushrooms’) are
evident. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.6 Peak absolute magnitudes of SNe Ia as a function of their LC
decline rate in the B band, Δm (B). . . . . . . . . . . . . . . . 2215
1.7 Top panel: SN-Ia Hubble diagram. The best-fitting flat ΛCDM
cosmology is overplotted on the observed data.
Bottom panel: Confidence contours for a parametrisation of the
equation-of-state parameter as w = w +w z/(1+z), obtained0 a
from high-z SN data using different priors.. . . . . . . . . . . . . 24
1.8 CC-models showing strong convection with dominant l = 1
mode in the neutrino-heated region below the shock. . . . . . . . 29
1.9 Ejecta distribution in Maeda et al.’s parametrised jet-model for
GRB-SNe. The resulting [Oi] λλ6300,6364 profiles for different
viewing angles are also shown. . . . . . . . . . . . . . . . . . . . 34
2.1 PSF-fittingSNphotometrywithsnoopy. Fromlefttorightthe
original image, the fit of the background, the fitted SN PSF and
the residuals after SN subtraction are displayed. . . . . . . . . . 46
2.2 Template-subtraction technique, shown for an R-band image of
SN 2005bl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
34 LIST OF FIGURES
2.3 Instrumental BVRI/ri passbands used for the observations of
SNe 2004aw and 2005bl. . . . . . . . . . . . . . . . . . . . . . . . 50
2.4 Two-dimensional spectroscopic image of SN 2004aw taken on
2004 April 14 with CAFOS. Overplotted is the extracted, back-
ground-subtracted 1D spectrum which results from apall. . . . 52
3.1 High-velocity features in the Siii λ6355 lines of a number of
SNe Ia at very early phases. The left panel shows the observed
lineprofiles, andsynowfitswithandwithouthigh-velocitySiii.
The residuals of the fits are shown in the right panel. . . . . . . . 64
3.2 ‘Zorro’ diagram, analysing the distribution of the principal iso-
topicgroupsinasampleofSNeIa. Theenclosedmassofdifferent
burning products is plotted vs. Δm (B). . . . . . . . . . . . . . 6715
3.3 Abundance stratification of SN 2002bo from tomography. A
larger degree of mixing in SN 2002bo than in the W7 model is
suggested. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.1 R-band image of the SN 2005bl field taken with the Calar Alto
2.2m Telescope + CAFOS on UT 2005 May 14.. . . . . . . . . . 74
4.2 B−R difference image of NGC 4070. Dark shades in the figure
correspond to red areas. . . . . . . . . . . . . . . . . . . . . . . . 81
4.3 Deep exposure of NGC 4070 and its neighbour NGC 4066 ob-
tained on UT 2006 March 28 with CAFOS. The distorted shape
of NGC 4070 and the bridge of luminous matter connecting the
two galaxies are discernible. . . . . . . . . . . . . . . . . . . . . . 84
4.4 UBVRI Bessell and gz Sloan light curves of SN 2005bl. Hamuy
et al.’s templates for SN 1991bg are shown for comparison. . . . 86
4.5 Quasi-bolometric light curves of SNe 2005bl, 1991bg, 1997cn,
1998de, 1999by, 2004eo and 2005cf, obtained by integrating the
U-through-I-band fluxes. . . . . . . . . . . . . . . . . . . . . . . 88
4.6 Time-evolution of the U−B, B−V, V −R and V −I colour
indices of SN 2005bl. . . . . . . . . . . . . . . . . . . . . . . . . . 90
4.7 Time sequence of SN 2005bl spectra in the observer frame. . . . 91
4.8 Comparison of pre-maximum spectra of underluminous SNe Ia.. 92
4.9 Like Fig. 4.8, but some days after maximum light in B. . . . . . 93
4.10 Like Fig. 4.8, but 4–5 weeks after maximum light in B. . . . . . 94
4.11 Spectroscopic comparison of SN 2005bl and the intermediate
decliner SN 2004eo at three different epochs. . . . . . . . . . . . 95