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

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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 _o 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
Article number	L18
Journal	Astrophysical Journal Letters
Volume	828
Issue number	2
DOIs	https://doi.org/10.3847/2041-8205/828/2/L18
State	Published - 10 Sep 2016
Externally published	Yes

Funding

Funders	Funder number
Science and Technology Facilities Council
Engineering Research Centers
Deutsche Forschungsgemeinschaft
European Commission
Alexander von Humboldt-Stiftung
Seventh Framework Programme	291222, 307260
National Science Foundation	1313484
UK Research and Innovation	ST/L000709/1

Keywords

supernovae: general
supernovae: individual (2015bn)

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10.3847/2041-8205/828/2/L18

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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, 828(2), Article L18. https://doi.org/10.3847/2041-8205/828/2/L18

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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 o 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.",

keywords = "supernovae: general, supernovae: individual (2015bn)",

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,

day = "10",

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

language = "אנגלית",

volume = "828",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

publisher = "American Astronomical Society",

number = "2",

}

Nicholl, M, Berger, E, Margutti, R, Chornock, R, Blanchard, PK, Jerkstrand, A, Smartt, SJ, Arcavi, I, Challis, P, Chambers, KC, Chen, TW, 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, vol. 828, no. 2, L18. https://doi.org/10.3847/2041-8205/828/2/L18

TY - JOUR

T1 - SUPERLUMINOUS SUPERNOVA SN 2015bn in the NEBULAR PHASE

T2 - 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 - 2016/9/10

Y1 - 2016/9/10

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 o 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 o 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.

KW - supernovae: general

KW - supernovae: individual (2015bn)

UR - http://www.scopus.com/inward/record.url?scp=84987875446&partnerID=8YFLogxK

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

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

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AN - SCOPUS:84987875446

SN - 2041-8205

VL - 828

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 2

M1 - L18

ER -

SUPERLUMINOUS SUPERNOVA SN 2015bn in the NEBULAR PHASE: EVIDENCE for the ENGINE-POWERED EXPLOSION of A STRIPPED MASSIVE STAR

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Keywords

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