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Khazov, D, Yaron, O, Gal-Yam, A, Manulis, I, Rubin, A, Kulkarni, SR, Arcavi, I, Kasliwal, MM, Ofek, EO, Cao, Y, Perley, DA, Sollerman, J, Horesh, A, Sullivan, M, Filippenko, AV, Nugent, PE, Howell, DA, Cenko, SB, Silverman, JM, Ebeling, H , Taddia, F, Johansson, J, Laher, RR, Surace, J, Rebbapragada, UD, Wozniak, PR and Matheson, T (2016) Flash Spectroscopy: Emission Lines from the Ionized Circumstellar Material Around <10-Day-Old Type II Supernovae. The Astrophysical Journal, 818 (1). ISSN 1538-4357
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Abstract
The American Astronomical Society. All rights reserved.Supernovae (SNe) embedded in dense circumstellar material (CSM) may show prominent emission lines in their early-time spectra (≤10 days after the explosion), owing to recombination of the CSM ionized by the shock-breakout flash. From such spectra ("flash spectroscopy"), we can measure various physical properties of the CSM, as well as the mass-loss rate of the progenitor during the year prior to its explosion. Searching through the Palomar Transient Factory (PTF and iPTF) SN spectroscopy databases from 2009 through 2014, we found 12 SNe II showing flash-ionized (FI) signatures in their first spectra. All are younger than 10 days. These events constitute 14% of all 84 SNe in our sample having a spectrum within 10 days from explosion, and 18% of SNe II observed at ages <5 days, thereby setting lower limits on the fraction of FI events. We classified as "blue/featureless" (BF) those events having a first spectrum that is similar to that of a blackbody, without any emission or absorption signatures. It is possible that some BF events had FI signatures at an earlier phase than observed, or that they lack dense CSM around the progenitor. Within 2 days after explosion, 8 out of 11 SNe in our sample are either BF events or show FI signatures. Interestingly, we found that 19 out of 21 SNe brighter than an absolute magnitude MR = -18.2 belong to the FI or BF groups, and that all FI events peaked above MR = -17.6 mag, significantly brighter than average SNe II.
| Item Type: | Article |
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| Uncontrolled Keywords: | 0201 Astronomical And Space Sciences, 0305 Organic Chemistry, 0306 Physical Chemistry (Incl. Structural) |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | American Astronomical Society |
| Date Deposited: | 17 Feb 2017 12:35 |
| Last Modified: | 03 Aug 2022 07:52 |
| DOI or ID number: | 10.3847/0004-637X/818/1/3 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/5610 |
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