C. Fransson - Stockholm University

C. Fransson
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C. Fransson
Stockholm University

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High Energy Astrophysical Phenomena (33)
Solar and Stellar Astrophysics (29)
Cosmology and Nongalactic Astrophysics (9)
Astrophysics of Galaxies (2)
High Energy Physics - Experiment (1)
Instrumentation and Methods for Astrophysics (1)

Publications Authored By C. Fransson

With the advent of new wide-field, high-cadence optical transient surveys, our understanding of the diversity of core-collapse supernovae has grown tremendously in the last decade. However, the pre-supernova evolution of massive stars, that sets the physical backdrop to these violent events, is theoretically not well understood and difficult to probe observationally. Here we report the discovery of the supernova iPTF13dqy = SN 2013fs, a mere ~3 hr after explosion. Read More

It has become clear during the last decades that the interaction between the supernova ejecta and the circumstellar medium is playing a major role both for the observational properties of the supernova and for understanding the evolution of the progenitor star leading up to the explosion. In addition, it provides an opportunity to understand the shock physics connected to both thermal and non-thermal processes, including relativistic particle acceleration, radiation processes and the hydrodynamics of shock waves. This chapter has an emphasis on the information we can get from radio and X-ray observations, but also their connection to observations in the optical and ultraviolet. Read More

Due to its proximity, SN 1987A offers a unique opportunity to directly observe the geometry of a stellar explosion as it unfolds. Here we present spectral and imaging observations of SN 1987A obtained ~10,000 days after the explosion with HST/STIS and VLT/SINFONI at optical and near-infrared wavelengths. These observations allow us to produce the most detailed 3D map of H-alpha to date, the first 3D maps for [Ca II] \lambda \lambda 7292, 7324, [O I] \lambda \lambda 6300, 6364 and Mg II \lambda \lambda 9218, 9244, as well as new maps for [Si I]+[Fe II] 1. Read More

Context: Research on supernovae (SNe) over the past decade has confirmed that there is a distinct class of events which are much more luminous (by $\sim2$ mag) than canonical core-collapse SNe (CCSNe). These events with visual peak magnitudes $\lesssim-21$ are called superluminous SNe (SLSNe). Aims: There are a few intermediate events which have luminosities between these two classes. Read More

We present photometry and spectroscopy of PS1-14bj, a hydrogen-poor superluminous supernova (SLSN) at redshift $z=0.5215$ discovered in the last months of the Pan-STARRS1 Medium Deep Survey. PS1-14bj stands out by its extremely slow evolution, with an observed rise of $\gtrsim 125$ rest-frame days, and exponential decline out to $\sim 250$ days past peak at a measured rate of $0. Read More

The progenitors of some supernovae (SNe) exhibit outbursts with super-Eddington luminosities prior to their final explosions. This behavior is common among Type IIn SNe, but the driving mechanisms of these precursors are not yet well understood. SNHunt 275 was announced as a possible new SN during May 2015. Read More

iPTF14atg, a subluminous peculiar Type Ia supernova (SN Ia) similar to SN 2002es, is the first SN Ia for which a strong UV flash was observed in the early-time light curves. This has been interpreted as evidence for a single-degenerate (SD) progenitor system where such a signal is expected from interactions between the SN ejecta and the non-degenerate companion star. Here, we compare synthetic observables of multi-dimensional state-of-the-art explosion models for different progenitor scenarios to the light curves and spectra of iPTF14atg. Read More

Both CO and SiO have been observed at early and late phases in SN 1987A. H_2 was predicted to form at roughly the same time as these molecules, but was not detected at early epochs. Here we report the detection of NIR lines from H_2 at 2. Read More

Supernova (SN) 1987A was a peculiar H-rich event with a long-rising (LR) light curve (LC), stemming from a compact blue supergiant star (BSG). Only a few similar events have been presented in the literature. We present new data for a sample of 6 LR Type II SNe (SNe II), 3 of which were discovered and observed by the Palomar Transient Factory (PTF) and 3 observed by the Caltech Core-Collapse Project (CCCP). Read More

We present optical observations of supernova SN 2014C, which underwent an unprecedented slow metamorphosis from H-poor type Ib to H-rich type IIn over the course of one year. The observed spectroscopic evolution is consistent with the supernova having exploded in a cavity before encountering a massive shell of the progenitor star's stripped hydrogen envelope. Possible origins for the circumstellar shell include a brief Wolf-Rayet fast wind phase that overtook a slower red supergiant wind, eruptive ejection, or confinement of circumstellar material by external influences of neighboring stars. Read More

The observational effects of the 'Infrared Catastrophe' are discussed in view of the very late observations of the Type Ia SN 2011fe. Our model spectra at 1000d take non-local radiative transfer into account, and find that this has a crucial impact on the spectral formation. Although rapid cooling of the ejecta to a few 100 K occurs also in these models, the late-time optical/NIR flux is brighter by 1-2 magnitudes due to redistribution of UV emissivity, resulting from non-thermal excitation and ionization. Read More

Searches for circumstellar material around Type Ia supernovae (SNe Ia) are one of the most powerful tests of the nature of SN Ia progenitors, and radio observations provide a particularly sensitive probe of this material. Here we report radio observations for SNe Ia and their lower-luminosity thermonuclear cousins. We present the largest, most sensitive, and spectroscopically diverse study of prompt (delta t <~ 1 yr) radio observations of 85 thermonuclear SNe, including 25 obtained by our team with the unprecedented depth of the Karl G. Read More

We present all X-ray and radio observations of the Type IIn supernova SN 2010jl. The X-ray observations cover a period up to day 1500 with Chandra, XMM-Newton, NuSTAR and Swift-XRT. The Chandra observations after 2012 June, the XMM-Newton observation in 2013 November, and most of the Swift-XRT observations until 2014 December are presented for the first time. Read More

We present imaging and spectroscopic observations with HST and VLT of the ring of SN 1987A from 1994 to 2014. After an almost exponential increase of the shocked emission from the hotspots up to day ~8,000 (~2009), both this and the unshocked emission are now fading. From the radial positions of the hotspots we see an acceleration of these up to 500-1000 km/s, consistent with the highest spectroscopic shock velocities from the radiative shocks. Read More

Measurements of explosive nucleosynthesis yields in core-collapse supernovae provide tests for explosion models. We investigate constraints on explosive conditions derivable from measured amounts of nickel and iron after radioactive decays using nucleosynthesis networks with parameterized thermodynamic trajectories. The Ni/Fe ratio is for most regimes dominated by the production ratio of 58Ni/(54Fe + 56Ni), which tends to grow with higher neutron excess and with higher entropy. Read More

Context. Some circumstellar-interacting (CSI) supernovae (SNe) are produced by the explosions of massive stars that have lost mass shortly before the SN explosion. There is evidence that the precursors of some SNe IIn were luminous blue variable (LBV) stars. Read More

We present radio and X-ray observations of the nearby Type IIb Supernova 2013df in NGC4414 from 10 to 250 days after the explosion. The radio emission showed a peculiar soft-to-hard spectral evolution. We present a model in which inverse Compton cooling of synchrotron emitting electrons can account for the observed spectral and light curve evolution. Read More

We present new {\it Hubble Space Telescope} images of high-velocity H-$\alpha$ and Lyman-$\alpha$ emission in the outer debris of SN~1987A. The H-$\alpha$ images are dominated by emission from hydrogen atoms crossing the reverse shock. For the first time we observe emission from the reverse shock surface well above and below the equatorial ring, suggesting a bipolar or conical structure perpendicular to the ring plane. Read More

Left-over, ablated material from a possible non-degenerate companion can reveal itself after about one year in spectra of Type Ia SNe (SNe Ia). We have searched for such material in spectra of SN 2011fe (at 294 days after the explosion) and for SN 2014J (315 days past explosion). The observations are compared with numerical models simulating the expected line emission. Read More

In this letter we present an optical spectrum of SN 2011fe taken 1034 d after the explosion, several hundred days later than any other spectrum of a Type Ia supernova (disregarding light-echo spectra and local-group remnants). The spectrum is still dominated by broad emission features, with no trace of a light echo or interaction of the supernova ejecta with surrounding interstellar material. Comparing this extremely late spectrum to an earlier one taken 331 d after the explosion, we find that the most prominent feature at 331 d - [Fe III] emission around 4700 A - has entirely faded away, suggesting a significant change in the ionisation state. Read More

Affiliations: 1UCL, 2NASA Goddard Space Flight Center, 3UCL, 4University of Wisconsin, 5Universiteit Gent, 6Space Telescope Science Institute, 7CSIC-INTA, 8Louisiana State University, 9University of Canterbury, 10Stockholm University, 11Universiteit Gent, 12Cardiff University, 13Cardiff University, 14Koninklijke Sterrenwacht van Belgie, 15University of Virginia, 16National Radio Astronomy Observatory, 17Queen's University Belfast, 18Saclay, 19Rutherford Appleton Laboratory, 20Stockholm University, 21Rutherford Appleton Laboratory, 22Space Telescope Science Institute, 23Katholieke Universiteit Leuven, 24University of Western Australia, 25UCL, 26Koninklijke Sterrenwacht van Belgie, 27Keele University, 28Universiteit Gent, 29European Southern Observatory, Santiago, 30University of Western Australia, 31Katholieke Universiteit Leuven, 32Katholieke Universiteit Leuven, 33NASA/Ames Research Center, 34NASA Goddard Space Flight Center, 35Koninklijke Sterrenwacht van Belgie, 36UCL

We present new Herschel photometric and spectroscopic observations of Supernova 1987A, carried out in 2012. Our dedicated photometric measurements provide new 70 micron data and improved imaging quality at 100 and 160 micron compared to previous observations in 2010. Our Herschel spectra show only weak CO line emission, and provide an upper limit for the 63 micron [O I] line flux, eliminating the possibility that line contaminations distort the previously estimated dust mass. Read More

SN 2012ec is a Type IIP supernova (SN) with a progenitor detection and comprehensive photospheric-phase observational coverage. Here, we present Very Large Telescope and PESSTO observations of this SN in the nebular phase. We model the nebular [O I] 6300, 6364 lines and find their strength to suggest a progenitor main-sequence mass of 13-15 Msun. Read More

Affiliations: 1ICRAR/UWA, 2ICRAR/UWA, CAASTRO, 3UVA, NRAO, 4UVA, 5UCL, 6CAASTRO, SIfA, 7UCL, 8U Stockholm, 9CSIRO/CASS, 10U Ghent, 11U Arizona, 12U Keele, 13U Stockholm, 14U Valencia, DIPC, 15U Chalmers, OSO, 16STScI, JHU, 17HKU, 18UT Arlington, 19NASA/GSFC, 20ESO, 21U Keele

We present a comprehensive spectral and morphological analysis of the remnant of Supernova (SN) 1987A with the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA). The non-thermal and thermal components of the radio emission are investigated in images from 94 to 672 GHz ($\lambda$ 3.2 mm to 450 $\mu$m), with the assistance of a high-resolution 44 GHz synchrotron template from the ATCA, and a dust template from ALMA observations at 672 GHz. Read More

We present optical and near-infrared (NIR) photometry and spectroscopy as well as modelling of the lightcurves of the Type IIb supernova (SN) 2011dh. Our extensive dataset spans two years, and complemented with Spitzer mid-infrared (MIR) data, we use it to build an optical-to-MIR bolometric lightcurve between days 3 and 732. To model the bolometric lightcurve before day 400 we use a grid of hydrodynamical SN models and a bolometric correction determined with steady-state NLTE modelling. Read More

We investigate line formation processes in Type IIb supernovae (SNe) from 100 to 500 days post-explosion using spectral synthesis calculations. The modeling identifies the nuclear burning layers and physical mechanisms that produce the major emission lines, and the diagnostic potential of these. We compare the model calculations with data on the three best observed Type IIb SNe to-date - SN 1993J, SN 2008ax, and SN 2011dh. Read More

We report deep EVN and eMERLIN observations of the Type Ia SN 2014J in the nearby galaxy M 82. Our observations represent, together with JVLA observations of SNe 2011fe and 2014J, the most sensitive radio studies of Type Ia SNe ever. By combining data and a proper modeling of the radio emission, we constrain the mass-loss rate from the progenitor system of SN 2014J to $\dot{M} \lesssim 7. Read More

Affiliations: 1UC Berkeley, 2STScI, 3Caltech, 4UC Berkeley, 5Stockholm University, 6NOAO, 7NASA Goddard, 8TIFA, 9Chicago, 10UC Berkeley, 11UC Berkeley, 12Steward

The Type IIb supernova (SN) 1993J is one of only a few stripped-envelope supernovae with a progenitor star identified in pre-explosion images. SN IIb models typically invoke H envelope stripping by mass transfer in a binary system. For the case of SN 1993J, the models suggest that the companion grew to 22 M_solar and became a source of ultraviolet (UV) excess. Read More

Interaction of supernova (SN) ejecta with the optically thick circumstellar medium (CSM) of a progenitor star can result in a bright, long-lived shock breakout event. Candidates for such SNe include Type IIn and superluminous SNe. If some of these SNe are powered by interaction, then there should be a relation between their peak luminosity, bolometric light-curve rise time, and shock-breakout velocity. Read More

HST and ground based observations of the Type IIn SN 2010jl are analyzed, including photometry, spectroscopy in the ultraviolet, optical and NIR bands, 26-1128 days after first detection. At maximum the bolometric luminosity was $\sim 3\times10^{43}$ erg/s and even at 850 days exceeds $10^{42}$ erg/s. A NIR excess, dominating after 400 days, probably originates in dust in the circumstellar medium (CSM). Read More

Supernova (SN) explosions are crucial engines driving the evolution of galaxies by shock heating gas, increasing the metallicity, creating dust, and accelerating energetic particles. In 2012 we used the Atacama Large Millimeter/Submillimeter Array to observe SN 1987A, one of the best-observed supernovae since the invention of the telescope. We present spatially resolved images at 450um, 870um, 1. Read More

We present nebular phase optical and near-infrared spectroscopy of the Type IIP supernova SN 2012aw combined with NLTE radiative transfer calculations applied to ejecta from stellar evolution/explosion models. Our spectral synthesis models generally show good agreement with the ejecta from a MZAMS = 15 Msun progenitor star. The emission lines of oxygen, sodium, and magnesium are all consistent with the nucleosynthesis in a progenitor in the 14 - 18 Msun range. Read More

We present extensive radio and X-ray observations of SN\, 2012au, the energetic radio luminous supernova of type Ib that may be a link between subsets of hydrogen-poor superluminous and normal core-collapse supernovae. The observations closely follow models of synchrotron emission from shock heated circum-burst medium that has a wind density profile ($\rho \propto r^{-2}$). We infer a sub-relativistic velocity for the shock wave $v \approx 0. Read More

The origin of the blue supergiant (BSG) progenitor of Supernova (SN) 1987A has long been debated, along with the role that its sub-solar metallicity played. We now have a sample of 1987A-like SNe that arise from the core collapse (CC) of BSGs. The metallicity of the explosion sites of the known BSG SNe is investigated, as well as their association to star-forming regions. Read More

We report spectroscopic and imaging observations of rotational transitions of cold CO and SiO in the ejecta of SN1987A, the first such emission detected in a supernova remnant. In addition to line luminosities for the CO J=1-0, 2-1, 6-5, and 7-6 transitions, we present upper limits for all other transitions up to J=13-12, collectively measured from the Atacama Large Millimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), and the Herschel Spectral and Photometric Imaging REceiver (SPIRE). Simple models show the lines are emitted from at least 0. Read More

We present predictions for hydrogen and helium emission line luminosities from circumstellar matter around Type Ia supernovae (SNe Ia) using time dependent photoionization modeling. ESO/VLT optical echelle spectra of the SN Ia 2000cx were taken before and up to 70 days after maximum. We detect no hydrogen and helium lines, and place an upper limit on the mass loss rate for the putative wind of less than 1. Read More

Authors: The CTA Consortium, :, O. Abril, B. S. Acharya, M. Actis, G. Agnetta, J. A. Aguilar, F. Aharonian, M. Ajello, A. Akhperjanian, M. Alcubierre, J. Aleksic, R. Alfaro, E. Aliu, A. J. Allafort, D. Allan, I. Allekotte, R. Aloisio, E. Amato, G. Ambrosi, M. Ambrosio, J. Anderson, E. O. Angüner, L. A. Antonelli, V. Antonuccio, M. Antonucci, P. Antoranz, A. Aravantinos, A. Argan, T. Arlen, C. Aramo, T. Armstrong, H. Arnaldi, L. Arrabito, K. Asano, T. Ashton, H. G. Asorey, T. Aune, Y. Awane, H. Baba, A. Babic, N. Baby, J. Bähr, A. Bais, C. Baixeras, S. Bajtlik, M. Balbo, D. Balis, C. Balkowski, J. Ballet, A. Bamba, R. Bandiera, A. Barber, C. Barbier, M. Barceló, A. Barnacka, J. Barnstedt, U. Barres de Almeida, J. A. Barrio, A. Basili, S. Basso, D. Bastieri, C. Bauer, A. Baushev, U. Becciani, J. Becerra, J. Becerra, Y. Becherini, K. C. Bechtol, J. Becker Tjus, V. Beckmann, W. Bednarek, B. Behera, M. Belluso, W. Benbow, J. Berdugo, D. Berge, K. Berger, F. Bernard, T. Bernardino, K. Bernlöhr, B. Bertucci, N. Bhat, S. Bhattacharyya, B. Biasuzzi, C. Bigongiari, A. Biland, S. Billotta, T. Bird, E. Birsin, E. Bissaldi, J. Biteau, M. Bitossi, S. Blake, O. Blanch Bigas, P. Blasi, A. Bobkov, V. Boccone, M. Böttcher, L. Bogacz, J. Bogart, M. Bogdan, C. Boisson, J. Boix Gargallo, J. Bolmont, G. Bonanno, A. Bonardi, T. Bonev, P. Bonifacio, G. Bonnoli, P. Bordas, A. Borgland, J. Borkowski, R. Bose, O. Botner, A. Bottani, L. Bouchet, M. Bourgeat, C. Boutonnet, A. Bouvier, S. Brau-Nogué, I. Braun, T. Bretz, M. Briggs, M. Brigida, T. Bringmann, R. Britto, P. Brook, P. Brun, L. Brunetti, P. Bruno, N. Bucciantini, T. Buanes, J. Buckley, R. Bühler, V. Bugaev, A. Bulgarelli, T. Bulik, G. Busetto, S. Buson, K. Byrum, M. Cailles, R. Cameron, J. Camprecios, R. Canestrari, S. Cantu, M. Capalbi, P. Caraveo, E. Carmona, A. Carosi, R. Carosi, J. Carr, J. Carter, P. -H. Carton, R. Caruso, S. Casanova, E. Cascone, M. Casiraghi, A. Castellina, O. Catalano, S. Cavazzani, S. Cazaux, P. Cerchiara, M. Cerruti, E. Chabanne, P. Chadwick, C. Champion, R. Chaves, P. Cheimets, A. Chen, J. Chiang, L. Chiappetti, M. Chikawa, V. R. Chitnis, F. Chollet, A. Christof, J. Chudoba, M. Cieślar, A. Cillis, M. Cilmo, A. Codino, J. Cohen-Tanugi, S. Colafrancesco, P. Colin, J. Colome, S. Colonges, M. Compin, P. Conconi, V. Conforti, V. Connaughton, J. Conrad, J. L. Contreras, P. Coppi, J. Coridian, P. Corona, D. Corti, J. Cortina, L. Cossio, A. Costa, H. Costantini, G. Cotter, B. Courty, S. Couturier, S. Covino, G. Crimi, S. J. Criswell, J. Croston, G. Cusumano, M. Dafonseca, O. Dale, M. Daniel, J. Darling, I. Davids, F. Dazzi, A. de Angelis, V. De Caprio, F. De Frondat, E. M. de Gouveia Dal Pino, I. de la Calle, G. A. De La Vega, R. de los Reyes Lopez, B. de Lotto, A. De Luca, M. de Naurois, Y. de Oliveira, E. de Oña Wilhelmi, F. de Palma, V. de Souza, G. Decerprit, G. Decock, C. Deil, E. Delagnes, G. Deleglise, C. Delgado, D. della Volpe, P. Demange, G. Depaola, A. Dettlaff, T. Di Girolamo, C. Di Giulio, A. Di Paola, F. Di Pierro, G. di Sciascio, C. Díaz, J. Dick, R. Dickherber, H. Dickinson, V. Diez-Blanco, S. Digel, D. Dimitrov, G. Disset, A. Djannati-Ataï, M. Doert, M. Dohmke, W. Domainko, D. Dominis Prester, A. Donat, D. Dorner, M. Doro, J. -L. Dournaux, G. Drake, D. Dravins, L. Drury, F. Dubois, R. Dubois, G. Dubus, C. Dufour, D. Dumas, J. Dumm, D. Durand, V. Dwarkadas, J. Dyks, M. Dyrda, J. Ebr, E. Edy, K. Egberts, P. Eger, S. Einecke, C. Eleftheriadis, S. Elles, D. Emmanoulopoulos, D. Engelhaupt, R. Enomoto, J. -P. Ernenwein, M. Errando, A. Etchegoyen, P. A. Evans, A. Falcone, A. Faltenbacher, D. Fantinel, K. Farakos, C. Farnier, E. Farrell, G. Fasola, B. W. Favill, E. Fede, S. Federici, S. Fegan, F. Feinstein, D. Ferenc, P. Ferrando, M. Fesquet, P. Fetfatzis, A. Fiasson, E. Fillin-Martino, D. Fink, C. Finley, J. P. Finley, M. Fiorini, R. Firpo Curcoll, E. Flandrini, H. Fleischhack, H. Flores, D. Florin, W. Focke, C. Föhr, E. Fokitis, L. Font, G. Fontaine, M. Fornasa, A. Förster, L. Fortson, N. Fouque, A. Franckowiak, F. J. Franco, A. Frankowski, C. Fransson, G. W. Fraser, R. Frei, L. Fresnillo, C. Fruck, D. Fugazza, Y. Fujita, Y. Fukazawa, Y. Fukui, S. Funk, W. Gäbele, S. Gabici, R. Gabriele, A. Gadola, N. Galante, D. Gall, Y. Gallant, J. Gámez-García, M. Garczarczyk, B. García, R. Garcia López, D. Gardiol, F. Gargano, D. Garrido, L. Garrido, D. Gascon, M. Gaug, J. Gaweda, L. Gebremedhin, N. Geffroy, L. Gerard, A. Ghedina, M. Ghigo, P. Ghislain, E. Giannakaki, F. Gianotti, S. Giarrusso, G. Giavitto, B. Giebels, N. Giglietto, V. Gika, M. Giomi, P. Giommi, F. Giordano, N. Girard, E. Giro, A. Giuliani, T. Glanzman, J. -F. Glicenstein, N. Godinovic, V. Golev, M. Gomez Berisso, J. Gómez-Ortega, M. M. Gonzalez, A. González, F. González, A. González Muñoz, K. S. Gothe, T. Grabarczyk, M. Gougerot, R. Graciani, P. Grandi, F. Grañena, J. Granot, G. Grasseau, R. Gredig, A. Green, T. Greenshaw, T. Grégoire, A. Grillo, O. Grimm, M. -H. Grondin, J. Grube, M. Grudzinska, V. Gruev, S. Grünewald, J. Grygorczuk, V. Guarino, S. Gunji, G. Gyuk, D. Hadasch, A. Hagedorn, R. Hagiwara, J. Hahn, N. Hakansson, A. Hallgren, N. Hamer Heras, S. Hara, M. J. Hardcastle, D. Harezlak, J. Harris, T. Hassan, K. Hatanaka, T. Haubold, A. Haupt, T. Hayakawa, M. Hayashida, R. Heller, F. Henault, G. Henri, G. Hermann, R. Hermel, A. Herrero, O. Hervet, N. Hidaka, J. A. Hinton, K. Hirotani, D. Hoffmann, W. Hofmann, P. Hofverberg, J. Holder, J. R. Hörandel, D. Horns, D. Horville, J. Houles, M. Hrabovsky, D. Hrupec, H. Huan, B. Huber, J. -M. Huet, G. Hughes, T. B. Humensky, J. Huovelin, J. -F. Huppert, A. Ibarra, D. Ikawa, J. M. Illa, D. Impiombato, S. Incorvaia, S. Inoue, Y. Inoue, F. Iocco, K. Ioka, G. L. Israel, C. Jablonski, A. Jacholkowska, J. Jacquemier, M. Jamrozy, M. Janiak, P. Jean, C. Jeanney, J. J. Jimenez, T. Jogler, C. Johnson, T. Johnson, L. Journet, C. Juffroy, I. Jung, P. Kaaret, S. Kabuki, M. Kagaya, J. Kakuwa, C. Kalkuhl, R. Kankanyan, A. Karastergiou, K. Kärcher, M. Karczewski, S. Karkar, J. Kasperek, D. Kastana, H. Katagiri, J. Kataoka, K. Katarzyński, U. Katz, N. Kawanaka, D. Kazanas, N. Kelley-Hoskins, B. Kellner-Leidel, H. Kelly, E. Kendziorra, B. Khélifi, D. B. Kieda, T. Kifune, T. Kihm, T. Kishimoto, K. Kitamoto, W. Kluźniak, C. Knapic, J. Knapp, J. Knödlseder, F. Köck, J. Kocot, K. Kodani, J. -H. Köhne, K. Kohri, K. Kokkotas, D. Kolitzus, N. Komin, I. Kominis, Y. Konno, H. Köppel, P. Korohoda, K. Kosack, G. Koss, R. Kossakowski, R. Koul, G. Kowal, S. Koyama, J. Kozioł, T. Krähenbühl, J. Krause, H. Krawzcynski, F. Krennrich, A. Krepps, A. Kretzschmann, R. Krobot, P. Krueger, H. Kubo, V. A. Kudryavtsev, J. Kushida, A. Kuznetsov, A. La Barbera, N. La Palombara, V. La Parola, G. La Rosa, K. Lacombe, G. Lamanna, J. Lande, D. Languignon, J. S. Lapington, P. Laporte, B. Laurent, C. Lavalley, T. Le Flour, A. Le Padellec, S. -H. Lee, W. H. Lee, J. -P. Lefèvre, H. Leich, M. A. Leigui de Oliveira, D. Lelas, J. -P. Lenain, R. Leoni, D. J. Leopold, T. Lerch, L. Lessio, G. Leto, B. Lieunard, S. Lieunard, R. Lindemann, E. Lindfors, A. Liolios, A. Lipniacka, H. Lockart, T. Lohse, S. Lombardi, F. Longo, A. Lopatin, M. Lopez, R. López-Coto, A. López-Oramas, A. Lorca, E. Lorenz, F. Louis, P. Lubinski, F. Lucarelli, H. Lüdecke, J. Ludwin, P. L. Luque-Escamilla, W. Lustermann, O. Luz, E. Lyard, M. C. Maccarone, T. J. Maccarone, G. M. Madejski, A. Madhavan, M. Mahabir, G. Maier, P. Majumdar, G. Malaguti, G. Malaspina, S. Maltezos, A. Manalaysay, A. Mancilla, D. Mandat, G. Maneva, A. Mangano, P. Manigot, K. Mannheim, I. Manthos, N. Maragos, A. Marcowith, M. Mariotti, M. Marisaldi, S. Markoff, A. Marszałek, C. Martens, J. Martí, J. -M. Martin, P. Martin, G. Martínez, F. Martínez, M. Martínez, F. Massaro, A. Masserot, A. Mastichiadis, A. Mathieu, H. Matsumoto, F. Mattana, S. Mattiazzo, A. Maurer, G. Maurin, S. Maxfield, J. Maya, D. Mazin, L. Mc Comb, A. McCann, N. McCubbin, I. McHardy, R. McKay, K. Meagher, C. Medina, C. Melioli, D. Melkumyan, D. Melo, S. Mereghetti, P. Mertsch, M. Meucci, M. Meyer, J. Michałowski, P. Micolon, A. Mihailidis, T. Mineo, M. Minuti, N. Mirabal, F. Mirabel, J. M. Miranda, R. Mirzoyan, A. Mistò, T. Mizuno, B. Moal, R. Moderski, I. Mognet, E. Molinari, M. Molinaro, T. Montaruli, C. Monte, I. Monteiro, P. Moore, A. Moralejo Olaizola, M. Mordalska, C. Morello, K. Mori, G. Morlino, A. Morselli, F. Mottez, Y. Moudden, E. Moulin, I. Mrusek, R. Mukherjee, P. Munar-Adrover, H. Muraishi, K. Murase, A. StJ. Murphy, S. Nagataki, T. Naito, D. Nakajima, T. Nakamori, K. Nakayama, C. Naumann, D. Naumann, M. Naumann-Godo, P. Nayman, D. Nedbal, D. Neise, L. Nellen, A. Neronov, V. Neustroev, N. Neyroud, L. Nicastro, J. Nicolau-Kukliński, A. Niedźwiecki, J. Niemiec, D. Nieto, A. Nikolaidis, K. Nishijima, K. -I. Nishikawa, K. Noda, S. Nolan, R. Northrop, D. Nosek, N. Nowak, A. Nozato, L. Oakes, P. T. O'Brien, Y. Ohira, M. Ohishi, S. Ohm, H. Ohoka, T. Okuda, A. Okumura, J. -F. Olive, R. A. Ong, R. Orito, M. Orr, J. P. Osborne, M. Ostrowski, L. A. Otero, N. Otte, E. Ovcharov, I. Oya, A. Ozieblo, L. Padilla, I. Pagano, S. Paiano, D. Paillot, A. Paizis, S. Palanque, M. Palatka, J. Pallota, M. Palatiello, K. Panagiotidis, J. -L. Panazol, D. Paneque, M. Panter, M. R. Panzera, R. Paoletti, A. Papayannis, G. Papyan, J. M. Paredes, G. Pareschi, J. -M. Parraud, D. Parsons, G. Pauletta, M. Paz Arribas, M. Pech, G. Pedaletti, V. Pelassa, D. Pelat, M. d. C. Perez, M. Persic, P. -O. Petrucci, B. Peyaud, A. Pichel, D. Pieloth, E. Pierre, S. Pita, G. Pivato, F. Pizzolato, M. Platino, Ł. Platos, R. Platzer, S. Podkladkin, L. Pogosyan, M. Pohl, G. Pojmanski, J. D. Ponz, W. Potter, J. Poutanen, E. Prandini, J. Prast, R. Preece, F. Profeti, H. Prokoph, M. Prouza, M. Proyetti, I. Puerto-Giménez, G. Pühlhofer, I. Puljak, M. Punch, R. Pyzioł, E. J. Quel, J. Quesada, J. Quinn, A. Quirrenbach, E. Racero, S. Rainò, P. J. Rajda, M. Rameez, P. Ramon, R. Rando, R. C. Rannot, M. Rataj, M. Raue, D. Ravignani, P. Reardon, O. Reimann, A. Reimer, O. Reimer, K. Reitberger, M. Renaud, S. Renner, B. Reville, W. Rhode, M. Ribó, M. Ribordy, G. Richards, M. G. Richer, J. Rico, J. Ridky, F. Rieger, P. Ringegni, J. Ripken, P. R. Ristori, A. Rivière, S. Rivoire, L. Rob, G. Rodeghiero, U. Roeser, R. Rohlfs, G. Rojas, P. Romano, W. Romaszkan, G. E. Romero, S. R. Rosen, S. Rosier Lees, D. Ross, G. Rouaix, J. Rousselle, S. Rousselle, A. C. Rovero, F. Roy, S. Royer, B. Rudak, C. Rulten, M. Rupiński, F. Russo, F. Ryde, O. Saavedra, B. Sacco, E. O. Saemann, A. Saggion, V. Sahakian, K. Saito, T. Saito, Y. Saito, N. Sakaki, R. Sakonaka, A. Salini, F. Sanchez, M. Sanchez-Conde, A. Sandoval, H. Sandaker, E. Sant'Ambrogio, A. Santangelo, E. M. Santos, A. Sanuy, L. Sapozhnikov, S. Sarkar, N. Sartore, H. Sasaki, K. Satalecka, M. Sawada, V. Scalzotto, V. Scapin, M. Scarcioffolo, J. Schafer, T. Schanz, S. Schlenstedt, R. Schlickeiser, T. Schmidt, J. Schmoll, P. Schovanek, M. Schroedter, A. Schubert, C. Schultz, J. Schultze, A. Schulz, K. Schure, F. Schussler, T. Schwab, U. Schwanke, J. Schwarz, S. Schwarzburg, T. Schweizer, S. Schwemmer, U. Schwendicke, C. Schwerdt, A. Segreto, J. -H. Seiradakis, G. H. Sembroski, M. Servillat, K. Seweryn, M. Sharma, M. Shayduk, R. C. Shellard, J. Shi, T. Shibata, A. Shibuya, S. Shore, E. Shum, E. Sideras-Haddad, L. Sidoli, M. Sidz, J. Sieiro, M. Sikora, J. Silk, A. Sillanpää, B. B. Singh, G. Sironi, J. Sitarek, C. Skole, R. Smareglia, A. Smith, D. Smith, J. Smith, N. Smith, D. Sobczyńska, H. Sol, G. Sottile, M. Sowiński, F. Spanier, D. Spiga, S. Spyrou, V. Stamatescu, A. Stamerra, R. L. C. Starling, Ł. Stawarz, R. Steenkamp, C. Stegmann, S. Steiner, C. Stella, N. Stergioulas, R. Sternberger, M. Sterzel, F. Stinzing, M. Stodulski, Th. Stolarczyk, U. Straumann, E. Strazzeri, L. Stringhetti, A. Suarez, M. Suchenek, R. Sugawara, K. -H. Sulanke, S. Sun, A. D. Supanitsky, T. Suric, P. Sutcliffe, J. M. Sykes, M. Szanecki, T. 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Videla, C. Vigorito, P. Vincent, S. Vincent, J. Vink, N. Vlahakis, L. Vlahos, P. Vogler, V. Voisin, A. Vollhardt, H. -P. von Gunten, S. Vorobiov, C. Vuerli, V. Waegebaert, R. Wagner, R. G. Wagner, S. Wagner, S. P. Wakely, R. Walter, T. Walther, K. Warda, R. S. Warwick, P. Wawer, R. Wawrzaszek, N. Webb, P. Wegner, A. Weinstein, Q. Weitzel, R. Welsing, M. Werner, H. Wetteskind, R. J. White, A. Wierzcholska, S. Wiesand, A. Wilhelm, M. I. Wilkinson, D. A. Williams, R. Willingale, M. Winde, K. Winiarski, R. Wischnewski, Ł. Wiśniewski, P. Wojcik, M. Wood, A. Wörnlein, Q. Xiong, K. K. Yadav, H. Yamamoto, T. Yamamoto, R. Yamazaki, S. Yanagita, J. M. Yebras, D. Yelos, A. Yoshida, T. Yoshida, T. Yoshikoshi, P. Yu, V. Zabalza, M. Zacharias, A. Zajczyk, L. Zampieri, R. Zanin, A. Zdziarski, A. Zech, A. Zhao, X. Zhou, K. Zietara, J. Ziolkowski, P. Ziółkowski, V. Zitelli, C. Zurbach, P. Zychowski

Compilation of CTA contributions to the proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), which took place in 2-9 July, 2013, in Rio de Janeiro, Brazil Read More

The 2012 explosion of SN2009ip raises questions about our understanding of the late stages of massive star evolution. Here we present a comprehensive study of SN2009ip during its remarkable re-brightening(s). High-cadence photometric and spectroscopic observations from the GeV to the radio band obtained from a variety of ground-based and space facilities (including the VLA, Swift, Fermi, HST and XMM) constrain SN2009ip to be a low energy (E~ 10^50 erg for an ejecta mass ~ 0. Read More

We present optical and near-infrared (NIR) photometry and spectroscopy of the Type IIb supernova (SN) 2011dh for the first 100 days. We complement our extensive dataset with SWIFT ultra-violet (UV) and Spitzer mid-infrared (MIR) data to build a UV to MIR bolometric lightcurve using both photometric and spectroscopic data. Hydrodynamical modelling of the SN based on this bolometric lightcurve have been presented in Bersten (2012). Read More

We present a study of the morphology of the ejecta in Supernova 1987A based on images and spectra from the HST as well as integral field spectroscopy from VLT/SINFONI. The HST observations were obtained between 1994 - 2011 and primarily probe the outer hydrogen-rich zones of the ejecta. The SINFONI observations were obtained in 2005 and 2011 and instead probe the [Si I]/[Fe II] emission from the inner regions. Read More

We present observations with VLT and HST of the broad emission lines from the inner ejecta and reverse shock of SN 1987A from 1999 until 2012 (days 4381 -- 9100 after explosion). We detect broad lines from H-alpha, H-beta, Mg I], Na I, [O I], [Ca II] and a feature at 9220 A. We identify the latter line with Mg II 9218, 9244,most likely pumped by Ly-alpha fluorescence. Read More

SN 2004et is one of the nearest and best-observed Type IIP supernovae, with a progenitor detection as well as good photometric and spectroscopic observational coverage well into the nebular phase. Based on nucleosynthesis from stellar evolution/explosion models we apply spectral modeling to analyze its 140-700 day evolution from ultraviolet to mid-infrared. We find a M_ZAMS= 15 Msun progenitor star (with an oxygen mass of 0. Read More

We present X-ray, UV/optical, and radio observations of the stripped-envelope, core-collapse supernova (SN) 2011ei, one of the least luminous SNe IIb or Ib observed to date. Our observations begin with a discovery within 1 day of explosion and span several months afterward. Early optical spectra exhibit broad, Type II-like hydrogen Balmer profiles that subside rapidly and are replaced by Type Ib-like He-rich features on the timescale of one week. Read More

We present an observational study of the Type IIn supernovae (SNe IIn) 2005ip and 2006jd. Broad-band UV, optical and near-IR photometry, and visual-wavelength spectroscopy of SN 2005ip complement and extend upon published observations to 6.5 years past discovery. Read More

We present an optical and near-infrared photometric and spectroscopic study of supernova (SN) 2009kn spanning ~1.5 yr from the discovery. The optical spectra are dominated by the narrow (full width at half-maximum ~1000 km s^-1) Balmer lines distinctive of a Type IIn SN with P Cygni profiles. Read More

We report four years of radio and X-ray monitoring of the Type IIn supernova SN 2006jd at radio wavelengths with the Very Large Array, Giant Metrewave Radio Telescope and Expanded Very Large Array; at X-ray wavelengths with {\em Chandra}, {\em XMM-Newton} and {\em Swift}-XRT. We assume that the radio and X-ray emitting particles are produced by shock interaction with a dense circumstellar medium. The radio emission shows an initial rise that can be attributed to free-free absorption by cool gas mixed into the nonthermal emitting region; external free-free absorption is disfavored because of the shape of the rising light curves and the low gas column density inferred along the line of sight to the emission region. Read More

We report two epochs of Chandra-ACIS X-ray imaging spectroscopy of the nearby bright Type IIn supernova SN 2010jl, taken around 2 months and then a year after the explosion. The majority of the X-ray emission in both the spectra is characterized by a high temperature ($\ga 10$ keV) and is likely to be from the forward shocked region resulting from circumstellar interaction. The absorption column density in the first spectrum is high, ~ 10^{24} cm^{-2}, more than 3 orders of magnitude higher than the Galactic absorption column, and we attribute it to absorption by circumstellar matter. Read More

We present a generalized analytic formalism for the inverse Compton X-ray emission from hydrogen-poor supernovae and apply this framework to SN2011fe using Swift-XRT, UVOT and Chandra observations. We characterize the optical properties of SN2011fe in the Swift bands and find them to be broadly consistent with a "normal" SN Ia, however, no X-ray source is detected by either XRT or Chandra. We constrain the progenitor system mass loss rate to be lower than 2x10^-9 M_sun/yr (3sigma c. Read More