Superluminous Supernova SN 2015bn in the Nebular Phase: Evidence for the Engine-powered Explosion of a Stripped Massive Star

M. Nicholl; E. Berger; R. Margutti; R. Chornock; P. K. Blanchard; A. Jerkstrand; S. J. Smartt; I. Arcavi; P. Challis; K. C. Chambers; T. -W. Chen; P. S. Cowperthwaite; A. Gal-Yam; G. Hosseinzadeh; D. A. Howell; C. Inserra; E. Kankare; E. A. Magnier; K. Maguire; P. A. Mazzali; C. McCully; D. Milisavljevic; K. W. Smith; S. Taubenberger; S. Valenti; R. J. Wainscoat; O. Yaron; D. R. Young

doi:10.3847/2041-8205/828/2/L18

Superluminous Supernova SN 2015bn in the Nebular Phase: Evidence for the Engine-powered Explosion of a Stripped Massive Star

M. Nicholl, E. Berger, R. Margutti, R. Chornock, P. K. Blanchard, A. Jerkstrand, S. J. Smartt, I. Arcavi, P. Challis, K. C. Chambers, T. -W. Chen, P. S. Cowperthwaite, A. Gal-Yam, G. Hosseinzadeh, D. A. Howell, C. Inserra, E. Kankare, E. A. Magnier, K. Maguire, P. A. MazzaliC. McCully, D. Milisavljevic, K. W. Smith, S. Taubenberger, S. Valenti, R. J. Wainscoat, O. Yaron, D. R. Young

Physics and Astronomy

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Abstract

We present nebular-phase imaging and spectroscopy for the hydrogen-poor superluminous supernova (SLSN) SN 2015bn, at redshift z = 0.1136, spanning +250-400 days after maximum light. The light curve exhibits a steepening in the decline rate from 1.4 mag (100 days)^-1 to 1.7 mag (100 days)^-1, suggestive of a significant decrease in the opacity. This change is accompanied by a transition from a blue continuum superposed with photospheric absorption lines to a nebular spectrum dominated by emission lines of oxygen, calcium, and magnesium. There are no obvious signatures of circumstellar interaction or large ⁵⁶Ni mass. We show that the spectrum at +400 days is virtually identical to a number of energetic SNe Ic such as SN 1997dq, SN 2012au, and SN 1998bw, indicating similar core conditions and strengthening the link between “hypernovae”/long gamma-ray bursts and SLSNe. A single explosion mechanism may unify these events that span absolute magnitudes of -22 < M _B < -17. Both the light curve and spectrum of SN 2015bn are consistent with an engine-driven explosion ejecting 7-30 M _☉ of oxygen-dominated ejecta (for reasonable choices in temperature and opacity). A strong and relatively narrow O I λ7774 line, seen in a number of these energetic events but not in normal supernovae, may point to an inner shell that is the signature of a central engine....

Original language	English
Journal	Astrophysical Journal Letters
DOIs	https://doi.org/10.3847/2041-8205/828/2/L18
Publication status	Published - Sept 2016

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Nicholl, M., Berger, E., Margutti, R., Chornock, R., Blanchard, P. K., Jerkstrand, A., Smartt, S. J., Arcavi, I., Challis, P., Chambers, K. C., Chen, T. .-W., Cowperthwaite, P. S., Gal-Yam, A., Hosseinzadeh, G., Howell, D. A., Inserra, C., Kankare, E., Magnier, E. A., Maguire, K., ... Young, D. R. (2016). Superluminous Supernova SN 2015bn in the Nebular Phase: Evidence for the Engine-powered Explosion of a Stripped Massive Star. Astrophysical Journal Letters. https://doi.org/10.3847/2041-8205/828/2/L18

@article{bd9e265e75e546fa94e59a444539d6ce,

title = "Superluminous Supernova SN 2015bn in the Nebular Phase: Evidence for the Engine-powered Explosion of a Stripped Massive Star",

abstract = "We present nebular-phase imaging and spectroscopy for the hydrogen-poor superluminous supernova (SLSN) SN 2015bn, at redshift z = 0.1136, spanning +250-400 days after maximum light. The light curve exhibits a steepening in the decline rate from 1.4 mag (100 days)-1 to 1.7 mag (100 days)-1, suggestive of a significant decrease in the opacity. This change is accompanied by a transition from a blue continuum superposed with photospheric absorption lines to a nebular spectrum dominated by emission lines of oxygen, calcium, and magnesium. There are no obvious signatures of circumstellar interaction or large 56Ni mass. We show that the spectrum at +400 days is virtually identical to a number of energetic SNe Ic such as SN 1997dq, SN 2012au, and SN 1998bw, indicating similar core conditions and strengthening the link between “hypernovae”/long gamma-ray bursts and SLSNe. A single explosion mechanism may unify these events that span absolute magnitudes of -22 < M B < -17. Both the light curve and spectrum of SN 2015bn are consistent with an engine-driven explosion ejecting 7-30 M ☉ of oxygen-dominated ejecta (for reasonable choices in temperature and opacity). A strong and relatively narrow O I λ7774 line, seen in a number of these energetic events but not in normal supernovae, may point to an inner shell that is the signature of a central engine....",

author = "M. Nicholl and E. Berger and R. Margutti and R. Chornock and Blanchard, {P. K.} and A. Jerkstrand and Smartt, {S. J.} and I. Arcavi and P. Challis and Chambers, {K. C.} and Chen, {T. -W.} and Cowperthwaite, {P. S.} and A. Gal-Yam and G. Hosseinzadeh and Howell, {D. A.} and C. Inserra and E. Kankare and Magnier, {E. A.} and K. Maguire and Mazzali, {P. A.} and C. McCully and D. Milisavljevic and Smith, {K. W.} and S. Taubenberger and S. Valenti and Wainscoat, {R. J.} and O. Yaron and Young, {D. R.}",

year = "2016",

month = sep,

doi = "10.3847/2041-8205/828/2/L18",

language = "English",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

publisher = "Institute of Physics Publishing Ltd",

}

Nicholl, M, Berger, E, Margutti, R, Chornock, R, Blanchard, PK, Jerkstrand, A, Smartt, SJ, Arcavi, I, Challis, P, Chambers, KC, Chen, T-W, Cowperthwaite, PS, Gal-Yam, A, Hosseinzadeh, G, Howell, DA, Inserra, C, Kankare, E, Magnier, EA, Maguire, K, Mazzali, PA, McCully, C, Milisavljevic, D, Smith, KW, Taubenberger, S, Valenti, S, Wainscoat, RJ, Yaron, O & Young, DR 2016, 'Superluminous Supernova SN 2015bn in the Nebular Phase: Evidence for the Engine-powered Explosion of a Stripped Massive Star', Astrophysical Journal Letters. https://doi.org/10.3847/2041-8205/828/2/L18

TY - JOUR

T1 - Superluminous Supernova SN 2015bn in the Nebular Phase: Evidence for the Engine-powered Explosion of a Stripped Massive Star

AU - Nicholl, M.

AU - Berger, E.

AU - Margutti, R.

AU - Chornock, R.

AU - Blanchard, P. K.

AU - Jerkstrand, A.

AU - Smartt, S. J.

AU - Arcavi, I.

AU - Challis, P.

AU - Chambers, K. C.

AU - Chen, T. -W.

AU - Cowperthwaite, P. S.

AU - Gal-Yam, A.

AU - Hosseinzadeh, G.

AU - Howell, D. A.

AU - Inserra, C.

AU - Kankare, E.

AU - Magnier, E. A.

AU - Maguire, K.

AU - Mazzali, P. A.

AU - McCully, C.

AU - Milisavljevic, D.

AU - Smith, K. W.

AU - Taubenberger, S.

AU - Valenti, S.

AU - Wainscoat, R. J.

AU - Yaron, O.

AU - Young, D. R.

PY - 2016/9

Y1 - 2016/9

N2 - We present nebular-phase imaging and spectroscopy for the hydrogen-poor superluminous supernova (SLSN) SN 2015bn, at redshift z = 0.1136, spanning +250-400 days after maximum light. The light curve exhibits a steepening in the decline rate from 1.4 mag (100 days)-1 to 1.7 mag (100 days)-1, suggestive of a significant decrease in the opacity. This change is accompanied by a transition from a blue continuum superposed with photospheric absorption lines to a nebular spectrum dominated by emission lines of oxygen, calcium, and magnesium. There are no obvious signatures of circumstellar interaction or large 56Ni mass. We show that the spectrum at +400 days is virtually identical to a number of energetic SNe Ic such as SN 1997dq, SN 2012au, and SN 1998bw, indicating similar core conditions and strengthening the link between “hypernovae”/long gamma-ray bursts and SLSNe. A single explosion mechanism may unify these events that span absolute magnitudes of -22 < M B < -17. Both the light curve and spectrum of SN 2015bn are consistent with an engine-driven explosion ejecting 7-30 M ☉ of oxygen-dominated ejecta (for reasonable choices in temperature and opacity). A strong and relatively narrow O I λ7774 line, seen in a number of these energetic events but not in normal supernovae, may point to an inner shell that is the signature of a central engine....

AB - We present nebular-phase imaging and spectroscopy for the hydrogen-poor superluminous supernova (SLSN) SN 2015bn, at redshift z = 0.1136, spanning +250-400 days after maximum light. The light curve exhibits a steepening in the decline rate from 1.4 mag (100 days)-1 to 1.7 mag (100 days)-1, suggestive of a significant decrease in the opacity. This change is accompanied by a transition from a blue continuum superposed with photospheric absorption lines to a nebular spectrum dominated by emission lines of oxygen, calcium, and magnesium. There are no obvious signatures of circumstellar interaction or large 56Ni mass. We show that the spectrum at +400 days is virtually identical to a number of energetic SNe Ic such as SN 1997dq, SN 2012au, and SN 1998bw, indicating similar core conditions and strengthening the link between “hypernovae”/long gamma-ray bursts and SLSNe. A single explosion mechanism may unify these events that span absolute magnitudes of -22 < M B < -17. Both the light curve and spectrum of SN 2015bn are consistent with an engine-driven explosion ejecting 7-30 M ☉ of oxygen-dominated ejecta (for reasonable choices in temperature and opacity). A strong and relatively narrow O I λ7774 line, seen in a number of these energetic events but not in normal supernovae, may point to an inner shell that is the signature of a central engine....

U2 - 10.3847/2041-8205/828/2/L18

DO - 10.3847/2041-8205/828/2/L18

M3 - Article

SN - 2041-8205

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

ER -

Superluminous Supernova SN 2015bn in the Nebular Phase: Evidence for the Engine-powered Explosion of a Stripped Massive Star

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