University of Leicester
Browse
aa44751-22.pdf (4.23 MB)

Panning for gold, but finding helium: Discovery of the ultra-stripped supernova SN 2019wxt from gravitational-wave follow-up observations

Download (4.23 MB)
journal contribution
posted on 2023-09-14, 10:02 authored by I Agudo, L Amati, T An, FE Bauer, S Benetti, MG Bernardini, R Beswick, K Bhirombhakdi, T De Boer, M Branchesi, SJ Brennan, E Brocato, MD Caballero-García, E Cappellaro, N Castro Rodríguez, AJ Castro-Tirado, KC Chambers, E Chassande-Mottin, S Chaty, TW Chen, A Coleiro, S Covino, F Da'ammando, P Da'avanzo, V Da'elia, A Fiore, A Flörs, M Fraser, S Frey, C Frohmaier, M Fulton, L Galbany, C Gall, H Gao, J García-Rojas, G Ghirlanda, S Giarratana, JH Gillanders, M Giroletti, BP Gompertz, M Gromadzki, KE Heintz, J Hjorth, YD Hu, ME Huber, A Inkenhaag, L Izzo, ZP Jin, PG Jonker, DA Kann, EC Kool, R Kotak, G Leloudas, AJ Levan, CC Lin, JD Lyman, EA Magnier, K Maguire, I Mandel, B Marcote, D Mata Sánchez, S Mattila, A Melandri, MJ Michaåà  Owski, J Moldon, M Nicholl, A Nicuesa Guelbenzu, SR Oates, F Onori, M Orienti, R Paladino, Z Paragi, M Perez-Torres, E Pian, G Pignata, S Piranomonte, J Quirola-Vásquez, F Ragosta, A Rau, S Ronchini, A Rossi, R Sánchez-Ramírez, OS Salafia, S Schulze, SJ Smartt, KW Smith, J Sollerman, S Srivastav, RLC Starling, D Steeghs, HF Stevance, NR Tanvir, V Testa, MAP Torres, A Valeev, SD Vergani, D Vescovi, R Wainscost, D Watson, K Wiersema, Ł. Wyrzykowski, J. Yang, S. Yang, D. R. Young
We present the results from multi-wavelength observations of a transient discovered during an intensive follow-up campaign of S191213g, a gravitational wave (GW) event reported by the LIGO-Virgo Collaboration as a possible binary neutron star merger in a low latency search. This search yielded SN 2019wxt, a young transient in a galaxy whose sky position (in the 80% GW contour) and distance (∼150 Mpc) were plausibly compatible with the localisation uncertainty of the GW event. Initially, the transienta's tightly constrained age, its relatively faint peak magnitude (Mi ∼ -16.7 mag), and the r-band decline rate of ∼1 mag per 5 days appeared suggestive of a compact binary merger. However, SN 2019wxt spectroscopically resembled a type Ib supernova, and analysis of the optical-near-infrared evolution rapidly led to the conclusion that while it could not be associated with S191213g, it nevertheless represented an extreme outcome of stellar evolution. By modelling the light curve, we estimated an ejecta mass of only ∼0.1 M·, with 56Ni comprising ∼20% of this. We were broadly able to reproduce its spectral evolution with a composition dominated by helium and oxygen, with trace amounts of calcium. We considered various progenitor channels that could give rise to the observed properties of SN 2019wxt and concluded that an ultra-stripped origin in a binary system is the most likely explanation. Disentangling genuine electromagnetic counterparts to GW events from transients such as SN 2019wxt soon after discovery is challenging: in a bid to characterise this level of contamination, we estimated the rate of events with a volumetric rate density comparable to that of SN 2019wxt and found that around one such event per week can occur within the typical GW localisation area of O4 alerts out to a luminosity distance of 500 Mpc, beyond which it would become fainter than the typical depth of current electromagnetic follow-up campaigns.

History

Author affiliation

School of Physics & Astronomy, University of Leicester

Version

  • VoR (Version of Record)

Published in

Astronomy and Astrophysics

Volume

675

Pagination

A201 - A201

Publisher

EDP Sciences

issn

0004-6361

eissn

1432-0746

Copyright date

2023

Available date

2023-09-14

Language

en

Usage metrics

    University of Leicester Publications

    Categories

    Licence

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC