SN2020qlb (ZTF20abobpcb) is an extensively sampled hydrogen-poor superluminous supernova (SLSN-I) that is among the most luminous (max. Mg = -22:25+/-0:01 magnitudes) and long-rising (77.1 days from explosion to maximum) in a category of the brightest and longest rising SNe currently known in the Universe. SN2020qlb exhibits clear light-curve undulations, a phenomenon seen in other SLSNe but whose physical origin is still a mystery. This Master of Science Thesis discusses both the potential power source of these immense explosions as well as the power mechanisms behind the observed light-curve undulations. A particularly large set of photometric data in both the visible and ultraviolet ranges and covering the first 410 days after explosion, as well as 10 spectra are available for analysis. The explosion date is constrained to +/-0.28 days; the phase and magnitude of the peak luminosity are determined; light-curves for each telescope/filter combination are constructed; the g-r color evolution is plotted; the photospheric temperature and radius evolutions are estimated; the bolometric light-curve is constructed and compared with known power source models; and the rest-frame spectral evolution is plotted for analysis. SN2020qlb is found to meet all the known criteria to be a SLSN-I. A radioactive power source model based on the decay of 56Ni is rejected due to unphysical parameter results. A source model based on the dipole spindown energy deposition of a magnetar fits well the bulk portion of the bolometric light-curve with physically possible parameter values. Two full periods of about 32+/-6 day undulations are found on top of the bulk light-curve after subtracting the smooth model values. Evidence for them is also seen in each filter light-curve. Hypothetical power sources for these striking characteristics from the literature are analyzed and discussed. In summary, a magnetar source for the bulk of the light curve is favored. An external source for the undulations is favored, e.g. interaction with variations in the progenitor star’s circumstellar material, with a caveat that an explanation involving the break-down of model assumptions cannot be ruled out. Together they are favored to explain the entire light-curve of SN2020qlb.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:su-197602 |
| Date | January 2021 |
| Creators | West, Stuart |
| Publisher | Stockholms universitet, Institutionen för astronomi |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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