XW is supported by the National Natural Science Foundation of China (NSFC grants 12288102 & 12033003), Scholar Program of Beijing Academy of Science and Technology (DZ:BS202002), and Tencent Xplorer Prize. AP acknowledges support from PRIN-MIUR 2022. AMG acknowledges financial support by the European Union under the 2014–2020 ERDF Operational Programme and by the Department of Economic Transformation, Industry, Knowledge, and Universities of the Regional Government of Andalusia through the FEDER-UCA18-107404 grant. Y-ZC is supported by the National Natural Science Foundation of China (NSFC, Grant No. 12303054) and the International Centre of Supernovae, Yunnan Key Laboratory (No. 202302AN360001). MF is supported by a Royal Society-Science Foundation Ireland University Research Fellowship. EC acknowledges support of MIUR, PRIN 2017 (grant 20179ZF5KS). SM acknowledges support from the Magnus Ehrnrooth Foundation and the Vilho, Yrjö, and Kalle Väisälä Foundation. TMR acknowledges the financial support of the Vilho, Yrjö and Kalle Väisälä Foundation of the Finnish academy of Science and Letters through the Finnish postdoc pool. IS is supported by fundings from MIUR, PRIN 2017 (grant 20179ZF5KS), by the PRIN-INAF 2022 project ‘Shedding light on the nature of gap transients: from the observations to the models’, and by the doctoral grant funded by Istituto Nazionale di Astrofisica via the University of Padova and the Italian Ministry of Education, University and Research (MIUR). NER acknowledges partial support from MIUR, PRIN 2017 (grant 20179ZF5KS) ‘The new frontier of the Multi-Messenger Astrophysics: follow-up of electromagnetic transient counterparts of gravitational wave sources.’, from PRIN-INAF 2022 ‘Shedding light on the nature of gap transients: from the observations to the models’, from the Spanish MICINN grant PID2019-108709GB-I00 and FEDER funds, and from the program Unidad de Excelencia María de Maeztu CEX2020-001058-M. CPG acknowledges financial support from the Secretary of Universities and Research (Government of Catalonia) and by the Horizon 2020 Research and Innovation Programme of the European Union under the Marie Skłodowska-Curie and the Beatriu de Pinós 2021 BP 00168 programme, from the Spanish Ministerio de Ciencia e Innovación (MCIN) and the Agencia Estatal de Investigación (AEI) 10.13039/501100011033 under the PID2020-115253GA-I00 HOSTFLOWS project, and the program Unidad de Excelencia María de Maeztu CEX2020-001058.

SN 2019neq was a very fast evolving superluminous supernova. At a redshift z = 0.1059, its peak absolute magnitude was −21.5 ± 0.2 mag in g band. In this work, we present data and analysis from an extensive spectrophotometric follow-up campaign using multiple observational facilities. Thanks to a nebular spectrum of SN 2019neq, we investigated some of the properties of the host galaxy at the location of SN 2019neq and found that its metallicity and specific star formation rate are in a good agreement with those usually measured for SLSNe-I hosts. We then discuss the plausibility of the magnetar and the circumstellar interaction scenarios to explain the observed light curves, and interpret a nebular spectrum of SN 2019neq using published SUMO radiative-transfer models. The results of our analysis suggest that the spin-down radiation of a millisecond magnetar with a magnetic field B 6 × 1014 G could boost the luminosity of SN 2019neq.

With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2020-001058-M).

With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2020-001058).

Peer reviewed