Helium-rich Superluminous Supernovae from the Zwicky Transient FacilityShow others and affiliations
Number of Authors: 422020 (English)In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 902, no 1, article id L8Article in journal (Refereed) Published
Abstract [en]
Helium is expected to be present in the massive ejecta of some hydrogen-poor superluminous supernovae (SLSN-I). However, until now only one event has been identified with He features in its photospheric spectra (PTF10hgi). We present the discovery of a new He-rich SLSN-I, ZTF19aawfbtg (SN2019hge), atz = 0.0866. This event has more than 10 optical spectra at phases from -41 to +103 days relative to the peak, most of which match well with that of PTF10hgi. Confirmation comes from a near-IR spectrum taken at +34 days, revealing Heifeatures with P-Cygni profiles at 1.083 and 2.058 mu m. Using the optical spectra of PTF10hgi and SN2019hge as templates, we examined 70 other SLSNe-I discovered by Zwicky Transient Facility in the first two years of operation and found five additional SLSNe-I with distinct He-features. The excitation of Heiatoms in normal core-collapse supernovae requires nonthermal radiation, as proposed by previous studies. These He-rich events cannot be explained by the traditional(56)Ni mixing model because of their blue spectra, high peak luminosities, and long rise timescales. Magnetar models offer a possible solution since pulsar winds naturally generate high-energy particles, potential sources of nonthermal excitation. An alternative model is the interaction between the ejecta and dense H-poor circumstellar material, which may be supported by observed undulations in the light curves. These six SLSNe-Ib have relatively low-peak luminosities (rest frameM(g) = -20.06 0.16).
Place, publisher, year, edition, pages
2020. Vol. 902, no 1, article id L8
Keywords [en]
Supernovae, Type Ib supernovae
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:su:diva-187650DOI: 10.3847/2041-8213/abb8c5ISI: 000579276300001OAI: oai:DiVA.org:su-187650DiVA, id: diva2:1516033
2021-01-112021-01-112022-02-25Bibliographically approved