An environmental analysis of the fast transient AT2018cow and implications for its progenitor and late-time brightness

Release time:2023-03-22 Hits:

Impact Factor:4.8

DOI number:10.1093/mnras/stac3773

Journal:Monthly Notices of the Royal Astronomical Society

Abstract:The nature of the newly discovered fast blue optical transients (FBOTs) is still puzzling astronomers. In this paper, we carry out a comprehensive analysis of the molecular gas, ionized gas, and stellar populations in the environment of the nearby FBOT AT2018cow based on ALMA, VLT/MUSE, and HST/WFC3 observations. A prominent molecular concentration of 6 (± 1) × 106 M⊙ is found in the vicinity of AT2018cow, which has given rise to two active star-forming complexes with ages of 4 ± 1 and ≲2.5 Myr, respectively. Each star-forming complex has a stellar mass of 3 × 105 M⊙, and has photoionized a giant H II region with Hα luminosity even comparable to that of the 30 Dor mini-starburst region. AT2018cow is spatially coincident with one of the star-forming complexes; however, it is most likely to reside in its foreground since it has a much smaller extinction than the complex. Its progenitor could have been formed in a different star-forming event, and the non-detection of the associated stellar population constrains the progenitor’s age to be ≳10 Myr and initial mass to be ≲20 M⊙. We further find the late-time brightness of AT2018cow is unlikely to be a stellar object. Its brightness has slightly declined from 2 to 4 yr after explosion and is most likely to originate from AT2018cow itself due to some powering mechanism still working at such late times.

Co-author:Justyn R Maund, Yali Shao, Ida A Janiak

First Author:Ning-Chen Sun

Volume:519

Issue:3

Page Number:3785-3797

Translation or Not:no

Date of Publication:2023-01-06

Included Journals:SCI

Links to published journals:https://academic.oup.com/mnras/article-abstract/519/3/3785/6973226?redirectedFrom=fulltext