Seeing Double: ASASSN-18bt Exhibits a Two-component Rise in the Early-time K2 Light Curve

B. J. Shappee; T. W.S. Holoien; M. R. Drout; K. Auchettl; M. D. Stritzinger; C. S. Kochanek; K. Z. Stanek; E. Shaya; G. Narayan; J. S. Brown; S. Bose; D. Bersier; J. Brimacombe; Ping Chen; Subo Dong; S. Holmbo; B. Katz; J. A. Muñoz; R. L. Mutel; R. S. Post; J. L. Prieto; J. Shields; D. Tallon; T. A. Thompson; P. J. Vallely; S. Villanueva; L. Denneau; H. Flewelling; A. N. Heinze; K. W. Smith; B. Stalder; J. L. Tonry; H. Weiland; T. Barclay; G. Barentsen; A. M. Cody; J. Dotson; F. Foerster; P. Garnavich; M. Gully-Santiago; C. Hedges; S. Howell; D. Kasen; S. Margheim; R. Mushotzky; A. Rest; B. E. Tucker; A. Villar; A. Zenteno; G. Beerman; R. Bjella; G. Castillo; J. Coughlin; B. Elsaesser; S. Flynn; R. Gangopadhyay; K. Griest; M. Hanley; J. Kampmeier; R. Kloetzel; L. Kohnert; C. Labonde; R. Larsen; K. A. Larson; K. M. McCalmont-Everton; C. McGinn; L. Migliorini; J. Moffatt; M. Muszynski; V. Nystrom; D. Osborne; M. Packard; C. A. Peterson; M. Redick; L. H. Reedy; S. E. Ross; B. Spencer; K. Steward; J. E.Van Cleve; J. Vinícius De Miranda Cardoso; T. Weschler; A. Wheaton; J. Bulger; K. C. Chambers; H. A. Flewelling; M. E. Huber; T. B. Lowe; E. A. Magnier; A. S.B. Schultz; C. Z. Waters; M. Willman; E. Baron; Zhihao Chen; James M. Derkacy; Fang Huang; Linyi Li; Wenxiong Li; Xue Li; Jun Mo; Liming Rui; Hanna Sai; Lifan Wang; Lingzhi Wang; Xiaofeng Wang; Danfeng Xiang; Jicheng Zhang; Jujia Zhang; Kaicheng Zhang; Tianmeng Zhang; Xinghan Zhang; Xulin Zhao; P. J. Brown; J. J. Hermes; J. Nordin; S. Points; A. Sódor; G. M. Strampelli; A. Zenteno

doi:10.3847/1538-4357/aaec79

Seeing Double: ASASSN-18bt Exhibits a Two-component Rise in the Early-time K2 Light Curve

B. J. Shappee, T. W.S. Holoien, M. R. Drout, K. Auchettl, M. D. Stritzinger, C. S. Kochanek, K. Z. Stanek, E. Shaya, G. Narayan, J. S. Brown, S. Bose, D. Bersier, J. Brimacombe, Ping Chen, Subo Dong, S. Holmbo, B. Katz, J. A. Muñoz, R. L. Mutel, R. S. PostJ. L. Prieto, J. Shields, D. Tallon, T. A. Thompson, P. J. Vallely, S. Villanueva, L. Denneau, H. Flewelling, A. N. Heinze, K. W. Smith, B. Stalder, J. L. Tonry, H. Weiland, T. Barclay, G. Barentsen, A. M. Cody, J. Dotson, F. Foerster, P. Garnavich, M. Gully-Santiago, C. Hedges, S. Howell, D. Kasen, S. Margheim, R. Mushotzky, A. Rest, B. E. Tucker, A. Villar, A. Zenteno, G. Beerman, R. Bjella, G. Castillo, J. Coughlin, B. Elsaesser, S. Flynn, R. Gangopadhyay, K. Griest, M. Hanley, J. Kampmeier, R. Kloetzel, L. Kohnert, C. Labonde, R. Larsen, K. A. Larson, K. M. McCalmont-Everton, C. McGinn, L. Migliorini, J. Moffatt, M. Muszynski, V. Nystrom, D. Osborne, M. Packard, C. A. Peterson, M. Redick, L. H. Reedy, S. E. Ross, B. Spencer, K. Steward, J. E.Van Cleve, J. Vinícius De Miranda Cardoso, T. Weschler, A. Wheaton, J. Bulger, K. C. Chambers, H. A. Flewelling, M. E. Huber, T. B. Lowe, E. A. Magnier, A. S.B. Schultz, C. Z. Waters, M. Willman, E. Baron, Zhihao Chen, James M. Derkacy, Fang Huang, Linyi Li, Wenxiong Li, Xue Li, Jun Mo, Liming Rui, Hanna Sai, Lifan Wang, Lingzhi Wang, Xiaofeng Wang, Danfeng Xiang, Jicheng Zhang, Jujia Zhang, Kaicheng Zhang, Tianmeng Zhang, Xinghan Zhang, Xulin Zhao, P. J. Brown, J. J. Hermes, J. Nordin, S. Points, A. Sódor, G. M. Strampelli, A. Zenteno

Astronomy & Astrophysics

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Abstract

On 2018 February 4.41, the All-Sky Automated Survey for SuperNovae (ASAS-SN) discovered ASASSN-18bt in the K2 Campaign 16 field. With a redshift of z = 0.01098 and a peak apparent magnitude of B _max = 14.31, ASASSN-18bt is the nearest and brightest SNe Ia yet observed by the Kepler spacecraft. Here we present the discovery of ASASSN-18bt, the K2 light curve, and prediscovery data from ASAS-SN and the Asteroid Terrestrial-impact Last Alert System. The K2 early-time light curve has an unprecedented 30-minute cadence and photometric precision for an SN Ia light curve, and it unambiguously shows a ∼4 day nearly linear phase followed by a steeper rise. Thus, ASASSN-18bt joins a growing list of SNe Ia whose early light curves are not well described by a single power law. We show that a double-power-law model fits the data reasonably well, hinting that two physical processes must be responsible for the observed rise. However, we find that current models of the interaction with a nondegenerate companion predict an abrupt rise and cannot adequately explain the initial, slower linear phase. Instead, we find that existing published models with shallow ⁵⁶Ni are able to span the observed behavior and, with tuning, may be able to reproduce the ASASSN-18bt light curve. Regardless, more theoretical work is needed to satisfactorily model this and other early-time SNe Ia light curves. Finally, we use Swift X-ray nondetections to constrain the presence of circumstellar material (CSM) at much larger distances and lower densities than possible with the optical light curve. For a constant-density CSM, these nondetections constrain ρ < 4.5 × 10⁵ cm^-3 at a radius of 4 × 10¹⁵ cm from the progenitor star. Assuming a wind-like environment, we place mass loss limits of for v _w = 100 km s^-1, ruling out some symbiotic progenitor systems. This work highlights the power of well-sampled early-time data and the need for immediate multiband, high-cadence follow-up for progress in understanding SNe Ia.

Original language	English (US)
Article number	13
Journal	Astrophysical Journal
Volume	870
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/aaec79
State	Published - Jan 1 2019

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/1538-4357/aaec79

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Shappee, B. J., Holoien, T. W. S., Drout, M. R., Auchettl, K., Stritzinger, M. D., Kochanek, C. S., Stanek, K. Z., Shaya, E., Narayan, G., Brown, J. S., Bose, S., Bersier, D., Brimacombe, J., Chen, P., Dong, S., Holmbo, S., Katz, B., Muñoz, J. A., Mutel, R. L., ... Zenteno, A. (2019). Seeing Double: ASASSN-18bt Exhibits a Two-component Rise in the Early-time K2 Light Curve. Astrophysical Journal, 870(1), Article 13. https://doi.org/10.3847/1538-4357/aaec79

@article{9e8e02bd859f49ada68db3ae40af8e4c,

title = "Seeing Double: ASASSN-18bt Exhibits a Two-component Rise in the Early-time K2 Light Curve",

abstract = "On 2018 February 4.41, the All-Sky Automated Survey for SuperNovae (ASAS-SN) discovered ASASSN-18bt in the K2 Campaign 16 field. With a redshift of z = 0.01098 and a peak apparent magnitude of B max = 14.31, ASASSN-18bt is the nearest and brightest SNe Ia yet observed by the Kepler spacecraft. Here we present the discovery of ASASSN-18bt, the K2 light curve, and prediscovery data from ASAS-SN and the Asteroid Terrestrial-impact Last Alert System. The K2 early-time light curve has an unprecedented 30-minute cadence and photometric precision for an SN Ia light curve, and it unambiguously shows a ∼4 day nearly linear phase followed by a steeper rise. Thus, ASASSN-18bt joins a growing list of SNe Ia whose early light curves are not well described by a single power law. We show that a double-power-law model fits the data reasonably well, hinting that two physical processes must be responsible for the observed rise. However, we find that current models of the interaction with a nondegenerate companion predict an abrupt rise and cannot adequately explain the initial, slower linear phase. Instead, we find that existing published models with shallow 56Ni are able to span the observed behavior and, with tuning, may be able to reproduce the ASASSN-18bt light curve. Regardless, more theoretical work is needed to satisfactorily model this and other early-time SNe Ia light curves. Finally, we use Swift X-ray nondetections to constrain the presence of circumstellar material (CSM) at much larger distances and lower densities than possible with the optical light curve. For a constant-density CSM, these nondetections constrain ρ < 4.5 × 105 cm-3 at a radius of 4 × 1015 cm from the progenitor star. Assuming a wind-like environment, we place mass loss limits of for v w = 100 km s-1, ruling out some symbiotic progenitor systems. This work highlights the power of well-sampled early-time data and the need for immediate multiband, high-cadence follow-up for progress in understanding SNe Ia.",

author = "Shappee, {B. J.} and Holoien, {T. W.S.} and Drout, {M. R.} and K. Auchettl and Stritzinger, {M. D.} and Kochanek, {C. S.} and Stanek, {K. Z.} and E. Shaya and G. Narayan and Brown, {J. S.} and S. Bose and D. Bersier and J. Brimacombe and Ping Chen and Subo Dong and S. Holmbo and B. Katz and Mu{\~n}oz, {J. A.} and Mutel, {R. L.} and Post, {R. S.} and Prieto, {J. L.} and J. Shields and D. Tallon and Thompson, {T. A.} and Vallely, {P. J.} and S. Villanueva and L. Denneau and H. Flewelling and Heinze, {A. N.} and Smith, {K. W.} and B. Stalder and Tonry, {J. L.} and H. Weiland and T. Barclay and G. Barentsen and Cody, {A. M.} and J. Dotson and F. Foerster and P. Garnavich and M. Gully-Santiago and C. Hedges and S. Howell and D. Kasen and S. Margheim and R. Mushotzky and A. Rest and Tucker, {B. E.} and A. Villar and A. Zenteno and G. Beerman and R. Bjella and G. Castillo and J. Coughlin and B. Elsaesser and S. Flynn and R. Gangopadhyay and K. Griest and M. Hanley and J. Kampmeier and R. Kloetzel and L. Kohnert and C. Labonde and R. Larsen and Larson, {K. A.} and McCalmont-Everton, {K. M.} and C. McGinn and L. Migliorini and J. Moffatt and M. Muszynski and V. Nystrom and D. Osborne and M. Packard and Peterson, {C. A.} and M. Redick and Reedy, {L. H.} and Ross, {S. E.} and B. Spencer and K. Steward and Cleve, {J. E.Van} and {De Miranda Cardoso}, {J. Vin{\'i}cius} and T. Weschler and A. Wheaton and J. Bulger and Chambers, {K. C.} and Flewelling, {H. A.} and Huber, {M. E.} and Lowe, {T. B.} and Magnier, {E. A.} and Schultz, {A. S.B.} and Waters, {C. Z.} and M. Willman and E. Baron and Zhihao Chen and Derkacy, {James M.} and Fang Huang and Linyi Li and Wenxiong Li and Xue Li and Jun Mo and Liming Rui and Hanna Sai and Lifan Wang and Lingzhi Wang and Xiaofeng Wang and Danfeng Xiang and Jicheng Zhang and Jujia Zhang and Kaicheng Zhang and Tianmeng Zhang and Xinghan Zhang and Xulin Zhao and Brown, {P. J.} and Hermes, {J. J.} and J. Nordin and S. Points and A. S{\'o}dor and Strampelli, {G. M.} and A. Zenteno",

year = "2019",

month = jan,

day = "1",

doi = "10.3847/1538-4357/aaec79",

language = "English (US)",

volume = "870",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "1",

}

Shappee, BJ, Holoien, TWS, Drout, MR, Auchettl, K, Stritzinger, MD, Kochanek, CS, Stanek, KZ, Shaya, E, Narayan, G, Brown, JS, Bose, S, Bersier, D, Brimacombe, J, Chen, P, Dong, S, Holmbo, S, Katz, B, Muñoz, JA, Mutel, RL, Post, RS, Prieto, JL, Shields, J, Tallon, D, Thompson, TA, Vallely, PJ, Villanueva, S, Denneau, L, Flewelling, H, Heinze, AN, Smith, KW, Stalder, B, Tonry, JL, Weiland, H, Barclay, T, Barentsen, G, Cody, AM, Dotson, J, Foerster, F, Garnavich, P, Gully-Santiago, M, Hedges, C, Howell, S, Kasen, D, Margheim, S, Mushotzky, R, Rest, A, Tucker, BE, Villar, A, Zenteno, A, Beerman, G, Bjella, R, Castillo, G, Coughlin, J, Elsaesser, B, Flynn, S, Gangopadhyay, R, Griest, K, Hanley, M, Kampmeier, J, Kloetzel, R, Kohnert, L, Labonde, C, Larsen, R, Larson, KA, McCalmont-Everton, KM, McGinn, C, Migliorini, L, Moffatt, J, Muszynski, M, Nystrom, V, Osborne, D, Packard, M, Peterson, CA, Redick, M, Reedy, LH, Ross, SE, Spencer, B, Steward, K, Cleve, JEV, De Miranda Cardoso, JV, Weschler, T, Wheaton, A, Bulger, J, Chambers, KC, Flewelling, HA, Huber, ME, Lowe, TB, Magnier, EA, Schultz, ASB, Waters, CZ, Willman, M, Baron, E, Chen, Z, Derkacy, JM, Huang, F, Li, L, Li, W, Li, X, Mo, J, Rui, L, Sai, H, Wang, L, Wang, L, Wang, X, Xiang, D, Zhang, J, Zhang, J, Zhang, K, Zhang, T, Zhang, X, Zhao, X, Brown, PJ, Hermes, JJ, Nordin, J, Points, S, Sódor, A, Strampelli, GM & Zenteno, A 2019, 'Seeing Double: ASASSN-18bt Exhibits a Two-component Rise in the Early-time K2 Light Curve', Astrophysical Journal, vol. 870, no. 1, 13. https://doi.org/10.3847/1538-4357/aaec79

TY - JOUR

T1 - Seeing Double

T2 - ASASSN-18bt Exhibits a Two-component Rise in the Early-time K2 Light Curve

AU - Shappee, B. J.

AU - Holoien, T. W.S.

AU - Drout, M. R.

AU - Auchettl, K.

AU - Stritzinger, M. D.

AU - Kochanek, C. S.

AU - Stanek, K. Z.

AU - Shaya, E.

AU - Narayan, G.

AU - Brown, J. S.

AU - Bose, S.

AU - Bersier, D.

AU - Brimacombe, J.

AU - Chen, Ping

AU - Dong, Subo

AU - Holmbo, S.

AU - Katz, B.

AU - Muñoz, J. A.

AU - Mutel, R. L.

AU - Post, R. S.

AU - Prieto, J. L.

AU - Shields, J.

AU - Tallon, D.

AU - Thompson, T. A.

AU - Vallely, P. J.

AU - Villanueva, S.

AU - Denneau, L.

AU - Flewelling, H.

AU - Heinze, A. N.

AU - Smith, K. W.

AU - Stalder, B.

AU - Tonry, J. L.

AU - Weiland, H.

AU - Barclay, T.

AU - Barentsen, G.

AU - Cody, A. M.

AU - Dotson, J.

AU - Foerster, F.

AU - Garnavich, P.

AU - Gully-Santiago, M.

AU - Hedges, C.

AU - Howell, S.

AU - Kasen, D.

AU - Margheim, S.

AU - Mushotzky, R.

AU - Rest, A.

AU - Tucker, B. E.

AU - Villar, A.

AU - Zenteno, A.

AU - Beerman, G.

AU - Bjella, R.

AU - Castillo, G.

AU - Coughlin, J.

AU - Elsaesser, B.

AU - Flynn, S.

AU - Gangopadhyay, R.

AU - Griest, K.

AU - Hanley, M.

AU - Kampmeier, J.

AU - Kloetzel, R.

AU - Kohnert, L.

AU - Labonde, C.

AU - Larsen, R.

AU - Larson, K. A.

AU - McCalmont-Everton, K. M.

AU - McGinn, C.

AU - Migliorini, L.

AU - Moffatt, J.

AU - Muszynski, M.

AU - Nystrom, V.

AU - Osborne, D.

AU - Packard, M.

AU - Peterson, C. A.

AU - Redick, M.

AU - Reedy, L. H.

AU - Ross, S. E.

AU - Spencer, B.

AU - Steward, K.

AU - Cleve, J. E.Van

AU - De Miranda Cardoso, J. Vinícius

AU - Weschler, T.

AU - Wheaton, A.

AU - Bulger, J.

AU - Chambers, K. C.

AU - Flewelling, H. A.

AU - Huber, M. E.

AU - Lowe, T. B.

AU - Magnier, E. A.

AU - Schultz, A. S.B.

AU - Waters, C. Z.

AU - Willman, M.

AU - Baron, E.

AU - Chen, Zhihao

AU - Derkacy, James M.

AU - Huang, Fang

AU - Li, Linyi

AU - Li, Wenxiong

AU - Li, Xue

AU - Mo, Jun

AU - Rui, Liming

AU - Sai, Hanna

AU - Wang, Lifan

AU - Wang, Lingzhi

AU - Wang, Xiaofeng

AU - Xiang, Danfeng

AU - Zhang, Jicheng

AU - Zhang, Jujia

AU - Zhang, Kaicheng

AU - Zhang, Tianmeng

AU - Zhang, Xinghan

AU - Zhao, Xulin

AU - Brown, P. J.

AU - Hermes, J. J.

AU - Nordin, J.

AU - Points, S.

AU - Sódor, A.

AU - Strampelli, G. M.

AU - Zenteno, A.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - On 2018 February 4.41, the All-Sky Automated Survey for SuperNovae (ASAS-SN) discovered ASASSN-18bt in the K2 Campaign 16 field. With a redshift of z = 0.01098 and a peak apparent magnitude of B max = 14.31, ASASSN-18bt is the nearest and brightest SNe Ia yet observed by the Kepler spacecraft. Here we present the discovery of ASASSN-18bt, the K2 light curve, and prediscovery data from ASAS-SN and the Asteroid Terrestrial-impact Last Alert System. The K2 early-time light curve has an unprecedented 30-minute cadence and photometric precision for an SN Ia light curve, and it unambiguously shows a ∼4 day nearly linear phase followed by a steeper rise. Thus, ASASSN-18bt joins a growing list of SNe Ia whose early light curves are not well described by a single power law. We show that a double-power-law model fits the data reasonably well, hinting that two physical processes must be responsible for the observed rise. However, we find that current models of the interaction with a nondegenerate companion predict an abrupt rise and cannot adequately explain the initial, slower linear phase. Instead, we find that existing published models with shallow 56Ni are able to span the observed behavior and, with tuning, may be able to reproduce the ASASSN-18bt light curve. Regardless, more theoretical work is needed to satisfactorily model this and other early-time SNe Ia light curves. Finally, we use Swift X-ray nondetections to constrain the presence of circumstellar material (CSM) at much larger distances and lower densities than possible with the optical light curve. For a constant-density CSM, these nondetections constrain ρ < 4.5 × 105 cm-3 at a radius of 4 × 1015 cm from the progenitor star. Assuming a wind-like environment, we place mass loss limits of for v w = 100 km s-1, ruling out some symbiotic progenitor systems. This work highlights the power of well-sampled early-time data and the need for immediate multiband, high-cadence follow-up for progress in understanding SNe Ia.

AB - On 2018 February 4.41, the All-Sky Automated Survey for SuperNovae (ASAS-SN) discovered ASASSN-18bt in the K2 Campaign 16 field. With a redshift of z = 0.01098 and a peak apparent magnitude of B max = 14.31, ASASSN-18bt is the nearest and brightest SNe Ia yet observed by the Kepler spacecraft. Here we present the discovery of ASASSN-18bt, the K2 light curve, and prediscovery data from ASAS-SN and the Asteroid Terrestrial-impact Last Alert System. The K2 early-time light curve has an unprecedented 30-minute cadence and photometric precision for an SN Ia light curve, and it unambiguously shows a ∼4 day nearly linear phase followed by a steeper rise. Thus, ASASSN-18bt joins a growing list of SNe Ia whose early light curves are not well described by a single power law. We show that a double-power-law model fits the data reasonably well, hinting that two physical processes must be responsible for the observed rise. However, we find that current models of the interaction with a nondegenerate companion predict an abrupt rise and cannot adequately explain the initial, slower linear phase. Instead, we find that existing published models with shallow 56Ni are able to span the observed behavior and, with tuning, may be able to reproduce the ASASSN-18bt light curve. Regardless, more theoretical work is needed to satisfactorily model this and other early-time SNe Ia light curves. Finally, we use Swift X-ray nondetections to constrain the presence of circumstellar material (CSM) at much larger distances and lower densities than possible with the optical light curve. For a constant-density CSM, these nondetections constrain ρ < 4.5 × 105 cm-3 at a radius of 4 × 1015 cm from the progenitor star. Assuming a wind-like environment, we place mass loss limits of for v w = 100 km s-1, ruling out some symbiotic progenitor systems. This work highlights the power of well-sampled early-time data and the need for immediate multiband, high-cadence follow-up for progress in understanding SNe Ia.

UR - http://www.scopus.com/inward/record.url?scp=85059871487&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85059871487&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aaec79

DO - 10.3847/1538-4357/aaec79

M3 - Article

AN - SCOPUS:85059871487

SN - 0004-637X

VL - 870

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 13

ER -

Seeing Double: ASASSN-18bt Exhibits a Two-component Rise in the Early-time K2 Light Curve

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