2022A&A...666A..30P


Query : 2022A&A...666A..30P

2022A&A...666A..30P - Astronomy and Astrophysics, volume 666A, 30 (2022/10-1)

SN 2018bsz: A Type I superluminous supernova with aspherical circumstellar material.

PURSIAINEN M., LELOUDAS G., PARASKEVA E., CIKOTA A., ANDERSON J.P., ANGUS C.R., BRENNAN S., BULLA M., CAMACHO-INIGUEZ E., CHARALAMPOPOULOS P., CHEN T.-W., DELGADO MANCHENO M., FRASER M., FROHMAIER C., GALBANY L., GUTIERREZ C.P., GROMADZKI M., INSERRA C., MAUND J., MULLER-BRAVO T.E., MUNOZ TORRES S., NICHOLL M., ONORI F., PATAT F., PESSI P.J., ROY R., SPYROMILIO J., WISEMAN P. and YOUNG D.R.

Abstract (from CDS):

We present a spectroscopic analysis of the most nearby Type I superluminous supernova (SLSN-I), SN 2018bsz. The photometric evolution of SN 2018bsz has several surprising features, including an unusual pre-peak plateau and evidence for rapid formation of dust ≳200 d post-peak. We show here that the spectroscopic and polarimetric properties of SN 2018bsz are also unique. While its spectroscopic evolution closely resembles SLSNe-I, with early O II absorption and C II P Cygni profiles followed by Ca, Mg, Fe, and other O features, a multi-component Hα profile appearing at ∼30 d post-maximum is the most atypical. The Hα is at first characterised by two emission components, one at ∼+3000 km s–1 and a second at ∼ - 7500 km s–1, with a third, near-zero-velocity component appearing after a delay. The blue and central components can be described by Gaussian profiles of intermediate width (FWHM ∼ 2000-6000 km s–1), but the red component is significantly broader (FWHM ≳ 10 000 km s–1) and Lorentzian. The blue Hα component evolves towards a lower-velocity offset before abruptly fading at ∼ + 100 d post-maximum brightness, concurrently with a light curve break. Multi-component profiles are observed in other hydrogen lines, including Paβ, and in lines of Ca II and He I. Spectropolarimetry obtained before (10.2 d) and after (38.4 d) the appearance of the H lines shows a large shift on the Stokes Q - U plane consistent with SN 2018bsz undergoing radical changes in its projected geometry. Assuming the supernova is almost unpolarised at 10.2 d, the continuum polarisation at 38.4 d reaches P ∼ 1.8%, implying an aspherical configuration. We propose that the observed evolution of SN 2018bsz can be explained by highly aspherical, possibly disk-like, circumstellar material (CSM) with several emitting regions. After the supernova explosion, the CSM is quickly overtaken by the ejecta, but as the photosphere starts to recede, the different CSM regions re-emerge, producing the peculiar line profiles. Based on the first appearance of Hα, we can constrain the distance of the CSM to be less than ∼6.5 × 1015 cm (430 AU), or even lower (≲87 AU) if the pre-peak plateau is related to an eruption that created the CSM. The presence of CSM has been inferred previously for other SLSNe-I, both directly and indirectly. However, it is not clear whether the rare properties of SN 2018bsz can be generalised for SLSNe-I, for example in the context of pulsational pair instability, or whether they are the result of an uncommon evolutionary path, possibly involving a binary companion.

Abstract Copyright: © M. Pursiainen et al. 2022

Journal keyword(s): circumstellar matter - supernovae: individual: SN 2018bsz

Simbad objects: 43

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Number of rows : 43
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 iPTF 13iqb SN* 00 34 04.84 -09 42 17.9           SNIIn 65 0
2 CRTS CSS121015 J004244+132827 SN* 00 42 44.380 +13 28 26.20           SNII/IIB 31 0
3 SN 2013hx SN* 01 35 33.28 -57 57 50.6           SNIc 19 1
4 LSQ 12dlf SN* 01 50 29.80 -21 48 45.4           SNIc 51 0
5 SN 2007gr SN* 02 43 27.98 +37 20 44.7       12.77   SNIc 237 1
6 SN 2006gy SN* 03 17 27.06 +41 24 19.5       14.20   SNIIn 340 1
7 DES15C3hav SN* 03 31 52.17 -28 15 09.5           SLSN-I 16 0
8 OGLE 2012-SN-6 SN* 03 33 34.79 -74 23 40.1           SNIbn 33 0
9 OGLE16dmu SN* 04 48 26.34 -62 20 10.6           SLSN 7 0
10 SN 1987A SN* 05 35 28.020 -69 16 11.07           SNIIpec 4945 2
11 iPTF 13ehe SN* 06 53 21.50 +67 07 56.0           SLSN-I 71 0
12 2MASS J07371703+6535579 HXB 07 37 17.0432126424 +65 35 57.826001220           SNIIP 282 1
13 SN 2016wi SN* 07 58 50.67 +66 07 39.1           SLSN-I 40 0
14 SN 2006jd SN* 08 02 07.43 +00 48 31.5   22.5 21.8 20.4 21.3 SNIIn 112 1
15 SN 2008D SN* 09 09 30.625 +33 08 20.16     17.5     SNIb 406 1
16 SN 2005ip SN* 09 32 06.42 +08 26 44.4 18.1 18.7 18.5     SNII 191 1
17 PTF 10aagc SN* 09 39 56.923 +21 43 17.09           SLSN-I 27 0
18 SN 1993J SN* 09 55 24.77476 +69 01 13.7026   10.8 12.0     SNIIb 1419 1
19 PSN J10081059+5150570 s*b 10 08 10.58 +51 50 57.1           LBV 98 0
20 SN 2017egm SN* 10 19 05.620 +46 27 14.08           SLSN-I 78 0
21 LSQ 14mo ev 10 22 41.53 -16 55 14.4           SLSN-I 55 0
22 SN 2005bf SN* 10 23 56.99 -03 11 29.3     18.0     SNIb 204 1
23 NAME Homunculus Nebula ISM 10 45 03.5 -59 41 04           ~ 369 1
24 * eta Car Em* 10 45 03.545808 -59 41 03.95124 6.37 7.03 6.48 6.123 4.41 LBV 2442 0
25 PSST 17bek SN* 10 47 41.90 +26 50 06.0           SLSN-I 4 0
26 PSST 15br SN* 11 25 19.23 +08 14 18.5           SNSL 15 0
27 SN 2015bn SN* 11 33 41.57 +00 43 32.2           SNIc 136 0
28 SN 2013L SN* 11 45 29.55 -50 35 53.1           SNIIn 26 1
29 SN 1998S SN* 11 46 06.1 +47 28 55     12.2     SNIIn 464 1
30 SN 2008es SN* 11 56 49.13 +54 27 25.7           SNIIL 116 1
31 SN 2004aw SN* 11 57 50.24 +25 15 55.1   18.06       SNIc 201 1
32 iPTF 16eh SN* 12 41 06.21 +32 48 30.9           SLSN-I 24 0
33 PTF 12dam SN* 14 24 46.20 +46 13 48.3           SLSNIc 160 0
34 SN 2012aa SN* 14 52 33.48 -03 31 54.0           SNIc: 18 1
35 iPTF 13bvn SN* 15 00 00.152 +01 52 53.17           SNIb 172 0
36 DENIS J160938.8-320343 Sy2 16 09 39.056 -32 03 44.33   15.88       ~ 6 0
37 SN 2018bsz SN* 16 09 39.110 -32 03 45.63           SNII 42 0
38 PTF 09cnd SN* 16 12 08.94 +51 29 16.1           SLSNIc 114 0
39 iPTF 16bad SN* 17 16 39.73 +28 22 12.6           SLSN-I 30 0
40 V* RY Sct Be* 18 25 31.4771300232 -12 41 24.192361500 10.25 10.38 9.12 9.46   O9.7Ibep 300 2
41 SN 2019hcc SN* 21 00 20.92 -21 20 36.0           SLSN 5 0
42 SN 2009ip s*b 22 23 08.26 -28 56 52.4           LBV 349 0
43 SN 2001ig SN* 22 57 30.69 -41 02 25.9     14.5     SNIIb 174 1

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