Статья

DETECTION OF BROAD Hα EMISSION LINES IN THE LATE-TIME SPECTRA OF A HYDROGEN-POOR SUPERLUMINOUS SUPERNOVA

Lin YanInfrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA; [email protected]R. M. QuimbyDepartment of Astronomy, San Diego State University, San Diego, CA 92182, USAE. O. OfekDepartment of Particle Physics and Astrophysics, Faculty of Physics, The Weizmann Institute of Science, Rehovot 76100, IsraelA. Gal‐YamDepartment of Particle Physics and Astrophysics, Faculty of Physics, The Weizmann Institute of Science, Rehovot 76100, IsraelP. A. MazzaliAstrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UKD. A. PerleyDark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen, DenmarkP. M. VreeswijkDepartment of Particle Physics and Astrophysics, Faculty of Physics, The Weizmann Institute of Science, Rehovot 76100, IsraelG. LeloudasDark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen, DenmarkA. de CiaDepartment of Particle Physics and Astrophysics, Faculty of Physics, The Weizmann Institute of Science, Rehovot 76100, IsraelFrank J. MasciInfrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA; [email protected]S. B. CenkoAstrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771, USAY. CaoAstronomy Department, California Institute of Technology, Pasadena, CA 91125, USAS. R. KulkarniAstronomy Department, California Institute of Technology, Pasadena, CA 91125, USAP. E. NugentAstronomy Department, University of California, Berkeley, 501 Campbell Hall, Berkeley, CA 94720, USAUmaa D. RebbapragadaJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USAP. R. WoźniakSpace and Remote Sensing, ISR-2, MS-B244 Los Alamos National Laboratory Los Alamos, NM 87545, USAO. YaronDepartment of Particle Physics and Astrophysics, Faculty of Physics, The Weizmann Institute of Science, Rehovot 76100, Israel

2015en

ABI

Аннотация

Discovered by the intermediate Palomar Transient Factory (iPTF), iPTF13ehe is a hydrogen-poor\nsuperluminous supernova (SLSN) at z =0.3434, with properties similar to SN2007bi. The early observations show that iPTF13ehe rises within 83 - 148 days (rest-frame) to reach a peak bolometric\nluminosity of L^(peak)_(bol) ~1.3x10^(44) erg s^(-1), then decays very slowly at 0.015 magnitude per day. The measured ejecta velocity is ~13000km s^(-1). The inferred explosion characteristics, such as the ejecta mass\n(67 - 220M⊙), the total radiative and kinetic energy (E_(rad) ~10^(51) erg, E_(kin) ~2x10^(53) erg), is typical\nof SLSN-R events. However, the late-time spectrum taken at +251 days (rest, post-peak) reveals a\nBalmer Hα emission feature with broad and narrow components, which has never been detected before\namong other H-poor SLSNe. The broad component has a velocity width of ~4500km s^(-1) and has a\n~300km s^(-1) blue-ward shift relative to the narrow component. We interpret this broad Hα emission\nline as the interaction between the supernova ejecta and a H-rich circumstellar medium (CSM) shell,\nlocated at a distance of ~4 x 10^(16) cm from the explosion site. This ejecta-CSM interaction can produce the observed Hα luminosity of ~2x10^(41) erg s^(-1) and causes the rest-frame r-band LC to brighten\nat late times. The fact that the late-time spectra are not completely absorbed by the shock ionized\nCSM shell implies that its Thomson scattering optical depth is likely ≤ 1, thus setting upper limits on\nthe CSM mass ≤ 30M⊙ and the volume number density ≤ 4 x 10^8 cm ^(-3). The early-time spectra do\nnot show any H emission lines from this CSM shell, indicating that most of the H-atoms are already\nneutral and the shell is optically thin to the visible light. We predict that this shell should produce\nLyα absorption in the UV spectra. Of the existing models, a Pulsational Pair Instability Supernova\n(PPISN) model can naturally explain the observed 30M⊙ H-shell, ejected from a progenitor star with\nan initial mass of (95-150)M⊙ about 40 years ago. By searching the PTF database for events similar\nto iPTF13ehe, we estimate that about 10% of all SLSNe-I may have late-time Balmer emission lines\nfrom ejecta interactions with H-rich shells.

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Идентификаторы

DOI: 10.1088/0004-637x/814/2/108

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Цитирований: 4Использованных источников: 0

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