Examinando por Autor "Berger, E."

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    Close, bright, and boxy: the superluminous SN 2018hti
    (Oxford University Press, 2022-05-01) Fiore, A.; Benetti, S.; Nicholl, M.; Reguitti, A.; Cappellaro, E.; Campana, S.; Bose, S.; Paraskeva, E.; Berger, E.; Bravo, T.M.; Burke, J.; Cai, Y.-Z.; Chen, T.-W.; Chen, P.; Ciolfi, R.; Dong, S.; Gomez, S.; Gromadzki, M.; Gutiérrez, C.P.; Hiramatsu, D.; Hosseinzadeh, G.; Howell, D.A.; Jerkstrand, A.; Kankare, E.; Kozyreva, A.; Maguire, K.; McCully, C.; Ochner, P.; Pellegrino, C.; Pignata, G.; Post, R.S.; Elias-Rosa, N.; Shahbandeh, M.; Schuldt, S.; Thomas, B.P.; Tomasella, L.; Vinkó, J.; Vogl, C.; Wheeler, J.C.; Young, D.R.
    SN 2018hti was a very nearby (z = 0.0614) superluminous supernova with an exceedingly bright absolute magnitude of -21.7 mag in r band at maximum. The densely sampled pre-maximum light curves of SN 2018hti show a slow luminosity evolution and constrain the rise time to ∼50 rest-frame d. We fitted synthetic light curves to the photometry to infer the physical parameters of the explosion of SN 2018hti for both the magnetar and the CSM-interaction scenarios. We conclude that one of two mechanisms could be powering the luminosity of SN 2018hti; interaction with ∼10 M⊙ of circumstellar material or a magnetar with a magnetic field of Bp∼1.3 × 1013 G, and initial period of Pspin∼1.8 ms. From the nebular spectrum modelling we infer that SN 2018hti likely results from the explosion of a ∼40M⊙ progenitor star. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
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    The high-metallicity explosion environment of the relativistic supernova 2009bb1
    (2011) Levesque, E. M.; Soderberg, A. M.; Foley, R. J.; Berger, E.; Kewley, L. J.; Chakraborti, A. Ray; Torres, M. A. P.; Challis, P.; Kirshner, R. P.; Barthelmy, S. D.; Bietenholz, M. F.; Chandra, P.; Chaplin, V.; Chevalier, R. A.; Chugai, N.; Connaughton, V.; Copete, A.; Fox, O.; Fransson, C.; Grindlay, J. E.; Hamuy, M. A.; Milne, P. A.; Pignata, G.; Stritzinger, M. D.; Wieringa, M. H.
    We investigate the environment of the nearby (d 40 Mpc) broad-lined Type Ic supernova SN 2009bb. This event was observed to produce a relativistic outflow likely powered by a central accreting compact object. While such a phenomenon was previously observed only in long-duration gamma-ray bursts (LGRBs), no LGRB was detected in association with SN 2009bb. Using an optical spectrum of the SN 2009bb explosion site, we determine a variety of ISM properties for the host environment, including metallicity, young stellar population age, and star formation rate. We compare the SN explosion site properties to observations of LGRB and broad-lined SN Ic host environments on optical emission line ratio diagnostic diagrams. Based on these analyses, we find that the SN 2009bb explosion site has a metallicity between 1.7Z⊙ and 3.5Z⊙, in agreement with other broadined SN Ic host environments and at odds with the low-redshift LGRB host environments and recently proposed maximum metallicity limits for relativistic explosions. We consider the implications of these findings and the impact that SN 2009bb’s unusual explosive properties and environment have on our understanding of the key physical ingredient that enables some SNe to produce a relativistic outflow.