2019ApJ...870...13S

Query : 2019ApJ...870...13S

2019ApJ...870...13S - Astrophys. J., 870, 13-13 (2019/January-1)

Seeing double: ASASSN-18bt exhibits a two-component rise in the early-time K2 light curve.

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. (The ASAS-SN), BROWN J.S., BOSE S., BERSIER D., BRIMACOMBE J., CHEN P., DONG S., HOLMBO S., KATZ B., MUNOZ J.A., MUTEL R.L., POST R.S., PRIETO J.L., SHIELDS J., TALLON D., THOMPSON T.A., VALLELY P.J., VILLANUEVA S. (The ATLAS), DENNEAU L., FLEWELLING H., HEINZE A.N., SMITH K.W., STALDER B., TONRY J.L., WEILAND H., BARCLAY T., BARENTSEN G., CODY A.M., DOTSON J., FOERSTER F., GARNAVICH P., GULLY-SANTIAGO M., HEDGES C., HOWELL S., KASEN D., MARGHEIM S., MUSHOTZKY R., REST A., TUCKER B.E., VILLAR A., ZENTENO A. (The Kepler Spacecraft Team), 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 K.A., McCALMONT-EVERTON K.M., McGINN C., MIGLIORINI L., MOFFATT J., MUSZYNSKI M., NYSTROM V., OSBORNE D., PACKARD M., PETERSON C.A., REDICK M., REEDY L.H., ROSS S.E., SPENCER B., STEWARD K., VAN CLEVE J.E., VINICIUS DE MIRANDA CARDOSO J., WESCHLER T., WHEATON A. (The Pan-STARRS), BULGER J., CHAMBERS K.C., FLEWELLING H.A., HUBER M.E., LOWE T.B., MAGNIER E.A., SCHULTZ A.S.B., WATERS C.Z., WILLMAN M., BARON E., CHEN Z., DERKACY J.M., 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 P.J., HERMES J.J., NORDIN J., POINTS S., SODOR A., STRAMPELLI G.M. and ZENTENO A.

Abstract (from CDS):

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 Bmax = 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 x 105 cm–3 at a radius of 4 x 1015 cm from the progenitor star. Assuming a wind-like environment, we place mass loss limits of {dot}M< 8× 10–6M☉yr–1 for vw = 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.

Abstract Copyright: © 2018. The American Astronomical Society. All rights reserved.

Journal keyword(s): supernovae: individual: (ASASSN-18bt, SN 2018oh)

VizieR on-line data: <Available at CDS (J/ApJ/870/13): table1.dat>

Simbad objects: 17

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Number of rows : 17
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 SN 2009ig SN* 02 38 11.62 -01 18 45.3           SNIa-norm 168 1
2 SN 2012fr SN* 03 33 35.99 -36 07 37.7           SNIa-norm 178 1
3 SN 2013gy SN* 03 42 16.9 -04 43 18           SNIa-norm 55 1
4 SN 2015F SN* 07 36 15.76 -69 30 23.0           SNIa 100 1
5 Z 90-74 GiG 09 06 39.54126 +19 20 10.4907   15.0       ~ 38 0
6 SN 2018oh SN* 09 06 39.6 +19 20 18           SNIa-norm 91 0
7 SN 2014J SN* 09 55 42.12 +69 40 25.9           SNIa-norm 456 1
8 SN 2012cg SN* 12 27 12.83 +09 25 13.2           SNIa-norm 224 1
9 ASASSN -14lp SN* 12 45 09.1 -00 27 32           SNIa-norm 75 0
10 SN 2016bln SN* 13 34 45.6 +13 51 14           SNIa-norm 62 0
11 SN 2011fe SN* 14 03 05.711 +54 16 25.22   10.12 10.06     SNIa-norm 747 1
12 SN 2017cbv SN* 14 32 34.420 -44 08 02.74           SNIa 146 0
13 KSN 2011a SN* 19 00 03.868 +44 32 07.95           SNIIP 12 0
14 KSN 2011b SN* 19 20 37.540 +38 15 08.34           SNIa 14 0
15 KSN 2011c SN* 19 24 46.089 +43 40 50.68           SNIa 8 0
16 KSN 2012a SN* 19 33 30.1 +45 15 01           SNIa 12 0
17 SN 2013dy SN* 22 18 17.5 +40 34 09           SNIa-norm 128 0

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