Anders Nyholm Supernova surroundings on circumstellar and galactic scales Supernova surroundings on circumstellar and galactic scales on circumstellar and surroundings Supernova Anders Nyholm ISBN 978-91-7797-803-9 Department of Astronomy Doctoral Thesis in Astronomy at Stockholm University, Sweden 2019 Supernova surroundings on circumstellar and galactic scales Anders Nyholm Academic dissertation for the Degree of Doctor of Philosophy in Astronomy at Stockholm University to be publicly defended on Monday 23 September 2019 at 13.00 in sal FB42, AlbaNova universitetscentrum, Roslagstullsbacken 21. Abstract Some stars cease to be in a bright and destructive display called a supernova. This thesis explores what we can learn about supernovae (SNe) by studying their immediate surroundings, and what the SNe can teach us about their environments. The work presented is mostly based on the rich harvest of observations from 2009-2017 by the Palomar Transient Factory (PTF) and its successor, the intermediate PTF (iPTF). The PTF/iPTF was an untargeted sky survey at Palomar Observatory, aimed at finding and following up astronomical transients, such as SNe. During its existence, a massive star typically loses several solar masses of material. If much mass is lost in the decades or centuries before the SN, this material around the star (the circumstellar medium, CSM) will be quickly swept up by the ejecta of the eventual SN. This interaction can contribute strongly to the luminosity of the SN and make the light curve of an interacting SN carry signs of the progenitor star mass loss history. SNe with a hydrogen-rich CSM are called SNe Type IIn. A SN of this type, iPTF13z, found and followed by iPTF, had a slowly declining lightcurve with at least 5 major rebrightenings ("bumps") indicating rich structure in the CSM. Archival images clearly shows a precursor outburst about 210 days before the SN discovery, demonstrating the iPTF13z progenitor to be restless before its demise. Type IIn supernovae are heterogeneous, but only limited statistics has been done on samples. From PTF/iPTF, a sample of 42 SNe Type IIn was therefore selected, with photometry allowing their light curve rise times, decline rates and peak luminosities to be measured. It was shown that more luminous events are generally more long-lasting, but no strong correlation was found between rise times and peak luminosities. Two clusters of risetimes (around 20 and 50 days, respectively) were identified. The less long-lasting SNe Type IIn dominate the sample, suggesting that stars with a less extended dense CSM might be more common among SN Type IIn progenitors. Thermonuclear SNe (SNe Type Ia) are useful as standardisable candles, but no secure identification has yet been made of the progenitor system of a SN Type Ia. Using a late-time spectrum from the Nordic Optical Telescope of the nearby thermonuclear SN 2014J, a search for material ablated from a possible non-compact companion gave the upper limit of about 0.0085 solar masses of hydrogen-rich ablated gas. One likely explanation is that the SN 2014J progenitor system was a binary white dwarf. Supernovae are also useful tracers of the star formation history in their host galaxies, with SNe Type Ia tracing earlier epochs of star formation and exploding massive stars tracing more recent. For active galactic nuclei (AGN, the luminous centres of galaxies harbouring accreting supermassive black holes) SNe allows the so-called unification model to be tested. The unification model assumes that the main distinction between the two types of AGN is the viewing angle towards the central black hole, and that other properties (e.g. star formation history) of the host galaxies should be the same for the two AGN types. Matching 2190 SNe from PTF/iPTF to about 89000 AGN with spectra from the Sloan Digital Sky Survey, a significantly higher number of SNe in the hosts of AGN type 2 was found, challenging the unification model. Keywords: supernovae, circumstellar medium, SNe Type IIn, iPTF13z, intermediate Palomar Transient Factory, active galactic nuclei, SN 2014J. Stockholm 2019 http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-171451 ISBN 978-91-7797-803-9 ISBN 978-91-7797-804-6 Department of Astronomy Stockholm University, 106 91 Stockholm SUPERNOVA SURROUNDINGS ON CIRCUMSTELLAR AND GALACTIC SCALES Anders Nyholm Supernova surroundings on circumstellar and galactic scales Anders Nyholm ©Anders Nyholm, Stockholm University 2019 ISBN print 978-91-7797-803-9 ISBN PDF 978-91-7797-804-6 Cover image: Scenery with star trails, showing the dome of the 1.2 m Schmidt telescope (known as P48 or the Samuel Oschin Telescope) at Palomar Observatory, USA. After first light of P48 in 1948 and up until today, this venerable workhorse has been used for several important sky surveys, including the Palomar Transient Factory (PTF) and its successor, the intermediate PTF (iPTF). Papers II, III and IV in this thesis rely heavily on data from this telescope, obtained during PTF and iPTF. The image is cropped and used with permission. Photo credit: Palomar Observatory/California Institute of Technology Printed in Sweden by Universitetsservice US-AB, Stockholm 2019 Till Dasha List of included papers The four papers included in this PhD thesis will be referred to as Paper I, Paper II, Paper III and Paper IV. Their numeration is in chronological order. Summaries of the papers are given in Chapter 6. Paper I Lundqvist, P., Nyholm, A., Taddia, F., Sollerman, J., Johansson, J., Kozma, C., Lundqvist, N., Fransson, C., Garnavich, P. M., Kromer, M., Shappee, B. J. and Goobar, A. (2015). No trace of a single-degenerate companion in late spectra of supernovae 2011fe and 2014J. A&A, 577, A39. Paper II Villarroel, B., Nyholm, A., Karlsson, T., Comerón, S., Korn, A. J., Sollerman, J., and Zackrisson, E. (2017). AGN Luminosity and Stellar Age: Two Missing Ingredients for AGN Unification as Seen with iPTF Supernovae. ApJ, 837, 110V. Paper III Nyholm, A., Sollerman, J., Taddia, F., Fremling, C., Moriya, T. J., Ofek, E. O., Gal-Yam, A., De Cia, A., Roy, R., Kasliwal, M. M., Cao, Y., Nugent, P. E. and Masci, F. J. (2017). The bumpy light curve of Type IIn supernova iPTF13z over 3 years. A&A, 605, A6. Paper IV Nyholm, A., Sollerman, J., Tartaglia, L., Taddia, F., Fremling, C., Blagorodnova, N., Filippenko, A. V., Gal-Yam, A., Howell, D. A., Karamehmetoglu, E., Kulkarni, S. R., Laher, R., Masci, F., Leloudas, G., Kasliwal, M. M., Morå, K., Moriya, T. J., Ofek, E. O., Papadogiannakis, S., Quimby, R., Rebbapragada, U. and Schulze, S. (2019). Type IIn supernova light-curve properties measured from an untargeted survey sample. In review (A&A). Preprint: arXiv:1906.05812v1 Paper I, Paper III (©ESO) and Paper II (©AAS) reproduced with permission. Contributions of the author Contribution to Paper I: The author wrote the proposal to the Nordic Optical Telescope, manually reduced the spectrum of SN 2014J using IRAF (via PyRAF interface), wrote Section 2.2 in the paper, and contributed to the interpretation of the results. Lundqvist led the paper and the analysis. Contribution to Paper II: The author and Villarroel co-developed the idea (in the version applied here) to use supernovae for studying AGN hosts. The author provided the catalogue of PTF/iPTF supernovae, wrote and ran the computer scripts used to evaluate the presence of supernovae around AGN using the catalogues, wrote Sections 2.1, 2.2, 2.5 and 4.3 (Section 4.3.1 with contributions from Villarroel) and made Figure 3 in the paper, did the manual inspections mentioned in Sections 2.5 and 4.3.1, and contributed to the interpretation of the results. Karlsson did the statistical work. Contribution to Paper III: The author led the work on the paper and, from 2014, organised requests for photometry and spectra. The author wrote paper sections Abstract, 1, 2, 3.1, 3.2.3, 3.5, 3.6.1 and 4 (interpreting the results). A first, brief version of Section 3.6.2 was written by Moriya, then revised and expanded by the author (by e.g. adding the Monte Carlo experiment and making Figures 13 and 14 based on input from Moriya). The other sections were written together with Taddia. Figures 2, 5, 6 were drawn by the author. The remaining figures were prepared by Taddia and revised by the author. The photometry was obtained by Fremling from P48 and P60 images, as a part of his development of the FPIPE pipeline. Comments by Sollerman were incorporated in all parts of the paper. Contribution to Paper IV: The author initiated the project, selected the sample of supernovae, ran the PTFIDE pipeline for P48 photometry, wrote the manuscript (except for Appendix A and a part of Section 5.5) incorporating comments from co-authors, drew the figures (except Figures A.1 and A.2) and wrote a version of the NED distance calculator. Appendix A was written by Tartaglia (and modified by the author). Equation 3 and its adjacent text in Section 5.5 was written by Morå (who also wrote the script for the related statistical calculations). Karamehmetoglu helped developing the ∝ t2 rise time routine, Taddia assisted with figures, the cubic spline method and the Malmquist bias compensation. The GMM script used was by Papadogiannakis. Fremling ran FPIPE on P60 images. Re-use of material from the licentiate thesis of the author: Some of the introduction chapters of this PhD thesis (here called "P") are based on the introduction chapters of the author’s licentiate thesis (Nyholm, 2017, here called "L") as follows: P1 (L1), P1.1 (L1.1), P2 (L2), P2.1 (L2.1), P2.2 (L2.2 & L2.2.1), P2.3 (L2.3), P2.3.1 (L2.3.1), P2.3.2 (L2.3.2), P2.3.4 (L2.3.3), P2.3.5 (L2.3.4), P3 (L3), P3.1 (L3.1), P3.2 (L3.2), P4 (L3.3), P4.1 (L3.3.1), P4.2 (L3.3.2), P5 (L4), P5.1 (L4.1), P5.1.1 (L4.1.1), P5.2 (L4.2), P5.2.1 (L4.2.3), P5.3 (L4.2.2), P5.3.2 (L4.2.2), P5.3.3 (L4.2.2), P5.3.4 (L4.2.2), P5.3.5 (L4.4), P5.3.6 (L5.3.1 & L5.5.2), P5.4 (L4.3).