TY - JOUR
T1 - DETECTION of BROAD Hα EMISSION LINES in the LATE-TIME SPECTRA of A HYDROGEN-POOR SUPERLUMINOUS SUPERNOVA
AU - [Unknown], Yan
AU - Quimby, R.
AU - Ofek, Eran Oded
AU - Gal-Yam, Avishay
AU - Mazzali, P.
AU - Perley, D.
AU - Vreeswijk, P.M.
AU - Leloudas, Georgios
AU - De Cia, Cia, Annalisa
AU - Masci, F.
AU - Cenko, S.B.
AU - Cao, Y.
AU - Kulkarni, S.R.
AU - Nugent, P.E.
AU - Rebbapragada, U.D.
AU - Wozniak, P.R.
AU - Yaron, Ofer
N1 - We thank the anonymous referee for the positive and constructive suggestions, which have helped to improve the paper. We benefited from discussions with Nick Scoville and Orly Gnat on collisional excitations in ISM. We thank Mansi Kasliwal, Thomas Prince, and Howard Bond for helping us obtain the P200 photometry at one epoch. Vicki Toy and John Capone from University of Maryland are acknowledged for taking the photometry observation using LMI on DCT. A.G.Y. is supported by EU/FP7 via ERC grant No. 307260, the Quantum universe I-Core program by the Israeli Committee for planning and budgeting and the ISF; by Minerva and ISF grants; by the Weizmann-UK "making connections" program; and by Kimmel and ARCHES awards. The Dark Cosmology Centre is funded by the Danish National Research Foundation. This paper made use of Lowell Observatory's Discovery Channel Telescope (DCT). Lowell operates the DCT in partnership with Boston University, Northern Arizona University, the University of Maryland, and the University of Toledo. Partial support of the DCT was provided by Discovery Communications. The Large Monolithic Imager (LMI) on DCT was built by Lowell Observatory using funds from the National Science Foundation (AST-1005313). LANL participation in iPTF is supported by the US Department of Energy as a part of the Laboratory Directed Research and Development program. A portion of this work was carried out at the Jet Propulsion Laboratory under a Research and Technology Development Grant, under contract with the National Aeronautics and Space Administration. US Government support is acknowledged. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
PY - 2015/12/1
Y1 - 2015/12/1
N2 - iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z = 0.3434, with a slow-evolving light curve and spectral features similar to SN2007bi. It rises in 83-148 days to reach a peak bolometric luminosity of ∼1.3 × 1044 erg s-1, then decays slowly at 0.015 mag day-1. The measured ejecta velocity is ∼ 13,000 km s-1. The inferred explosion characteristics, such as the ejecta mass (70-220 Mo), and the total radiative and kinetic energy (Erad ∼ 1051 erg, Ekin ∼ 2 × 1053 erg), are typical of slow-evolving H-poor SLSN events. However, the late-time spectrum taken at +251 days (rest, post-peak) reveals a Balmer Hα emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ∼4500 km s-1 and a ∼300 km s-1 blueward shift relative to the narrow component. We interpret this broad Hα emission with a luminosity of ∼2 × 1041 erg s-1 as resulting from the interaction between the supernova ejecta and a discrete H-rich shell, located at a distance of ∼4 × 1016 cm from the explosion site. This interaction causes the rest-frame r-band LC to brighten at late times. The fact that the late-time spectra are not completely absorbed by the shock-ionized H-shell implies that its Thomson scattering optical depth is likely ≤1, thus setting upper limits on the shell mass ≤30 Mo. Of the existing models, a Pulsational Pair Instability supernova model can naturally explain the observed 30 Mo H-shell, ejected from a progenitor star with an initial mass of (95-150) Mo about 40 years ago. We estimate that at least ∼15% of all SLSNe-I may have late-time Balmer emission lines.
AB - iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z = 0.3434, with a slow-evolving light curve and spectral features similar to SN2007bi. It rises in 83-148 days to reach a peak bolometric luminosity of ∼1.3 × 1044 erg s-1, then decays slowly at 0.015 mag day-1. The measured ejecta velocity is ∼ 13,000 km s-1. The inferred explosion characteristics, such as the ejecta mass (70-220 Mo), and the total radiative and kinetic energy (Erad ∼ 1051 erg, Ekin ∼ 2 × 1053 erg), are typical of slow-evolving H-poor SLSN events. However, the late-time spectrum taken at +251 days (rest, post-peak) reveals a Balmer Hα emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ∼4500 km s-1 and a ∼300 km s-1 blueward shift relative to the narrow component. We interpret this broad Hα emission with a luminosity of ∼2 × 1041 erg s-1 as resulting from the interaction between the supernova ejecta and a discrete H-rich shell, located at a distance of ∼4 × 1016 cm from the explosion site. This interaction causes the rest-frame r-band LC to brighten at late times. The fact that the late-time spectra are not completely absorbed by the shock-ionized H-shell implies that its Thomson scattering optical depth is likely ≤1, thus setting upper limits on the shell mass ≤30 Mo. Of the existing models, a Pulsational Pair Instability supernova model can naturally explain the observed 30 Mo H-shell, ejected from a progenitor star with an initial mass of (95-150) Mo about 40 years ago. We estimate that at least ∼15% of all SLSNe-I may have late-time Balmer emission lines.
UR - http://www.scopus.com/inward/record.url?scp=84948779371&partnerID=8YFLogxK
U2 - 10.1088/0004-637X/814/2/108
DO - 10.1088/0004-637X/814/2/108
M3 - مقالة
SN - 0004-637X
VL - 814
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 108
ER -