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Title: Type Ibn Supernovae Show Photometric Homogeneity and Spectral Diversity at Maximum Light

Type Ibn supernovae (SNe) are a small yet intriguing class of explosions whose spectra are characterized by low-velocity helium emission lines with little to no evidence for hydrogen. The prevailing theory has been that these are the core-collapse explosions of very massive stars embedded in helium-rich circumstellar material (CSM). We report optical observations of six new SNe Ibn: PTF11rfh, PTF12ldy, iPTF14aki, iPTF15ul, SN 2015G, and iPTF15akq. This brings the sample size of such objects in the literature to 22. We also report new data, including a near-infrared spectrum, on the Type Ibn SN 2015U. In order to characterize the class as a whole, we analyze the photometric and spectroscopic properties of the full Type Ibn sample. Here, we find that, despite the expectation that CSM interaction would generate a heterogeneous set of light curves, as seen in SNe IIn, most Type Ibn light curves are quite similar in shape, declining at rates around 0.1 mag day -1 during the first month after maximum light, with a few significant exceptions. Early spectra of SNe Ibn come in at least two varieties, one that shows narrow P Cygni lines and another dominated by broader emission lines, both around maximum light, which maymore » be an indication of differences in the state of the progenitor system at the time of explosion. Alternatively, the spectral diversity could arise from viewing-angle effects or merely from a lack of early spectroscopic coverage. Finally, together, the relative light curve homogeneity and narrow spectral features suggest that the CSM consists of a spatially confined shell of helium surrounded by a less dense extended wind.« less
Authors:
ORCiD logo [1] ; ORCiD logo [2] ;  [3] ; ORCiD logo [1] ; ORCiD logo [1] ;  [4] ;  [5] ;  [6] ;  [6] ; ORCiD logo [7] ; ORCiD logo [8] ;  [9] ; ORCiD logo [10] ; ORCiD logo [7] ;  [6] ; ORCiD logo [9] ; ORCiD logo [11] ; ORCiD logo [5] ;  [7] ;  [5] more »; ORCiD logo [7] ;  [12] ; ORCiD logo [4] ; ORCiD logo [10] ;  [13] ;  [9] ; ORCiD logo [14] ; ORCiD logo [5] ; ORCiD logo [15] ;  [16] ; ORCiD logo [16] ; ORCiD logo [17] ; ORCiD logo [15] ;  [15] ; ORCiD logo [18] ; ORCiD logo [16] ;  [19] « less
  1. Las Cumbres Observatory, Goleta, CA (United States); Univ. of California, Santa Barbara, CA (United States). Dept. of Physics
  2. Las Cumbres Observatory, Goleta, CA (United States); Univ. of California, Santa Barbara, CA (United States). Kavli Inst. for Theoretical Physics
  3. Univ. of California, Davis, CA (United States). Dept. of Physics
  4. Weizmann Inst. of Science, Rehovot (Israel). Dept. of Particle Physics and Astrophysics
  5. Stockholm Univ. (Sweden). Oskar Klein Centre, Dept. of Astronomy
  6. INAF-Osservatorio Astronomico di Padova, Padova (Italy)
  7. California Inst. of Technology (CalTech), Pasadena, CA (United States). Cahill Center for Astronomy and Astrophysics
  8. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States). Astrophysics Science Division; Univ. of Maryland, College Park, MD (United States). Joint Space-Science Inst.
  9. Univ. of California, Berkeley, CA (United States). Dept. of Astronomy
  10. Texas Tech Univ., Lubbock, TX (United States). Dept. of Physics
  11. Space Telescope Science Inst., Baltimore, MD (United States)
  12. Univ. of Texas, Austin, TX (United States)
  13. Stockholm Univ. (Sweden). Oskar Klein Centre, Dept. of Astronomy, Albanova Univ. Centre
  14. Univ. of Cambridge (United Kingdom). Inst. of Astronomy
  15. Queen's Univ., Belfast (United Kingdom). Astrophysics Research Centre, School of Mathematics and Physics
  16. California Inst. of Technology (CalTech), Pasadena, CA (United States). Spitzer Science Center
  17. California Inst. of Technology (CalTech), La Canada Flintridge, CA (United States). Jet Propulsion Lab.
  18. Univ. of Southampton (United Kingdom). Dept. of Physics and Astronomy
  19. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-17-27743
Journal ID: ISSN 1538-4357; TRN: US1800408
Grant/Contract Number:
AC52-06NA25396; 1313484; 320360; 307260; 615929; 1545949
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 836; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Laboratory Directed Research and Development (LDRD) Program; National Science Foundation (NSF); Swedish Research Council (SRC)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Astronomy and Astrophysics; supernovae general; supernovae individual; PTF11rfh; PTF12ldy; iPTF14aki; SN 2015U; iPTF15ul; SN 2015G; iPTF15akq
OSTI Identifier:
1412905