Abstract
The many unusual properties of the enigmatic AT2018cow suggested that at
least some subset of the empirical class of fast blue optical
transients (FBOTs) represents a genuinely new astrophysical phenomenon.
Unfortunately, the intrinsic rarity and fleeting nature of these events
have made it difficult to identify additional examples early enough to
acquire the observations necessary to constrain theoretical models. We
present here the Zwicky Transient Facility discovery of AT2020xnd
(ZTF20acigmel, the ‘Camel’) at z = 0.243, the first unambiguous
AT2018cow analogue to be found and confirmed in real time. AT2018cow
and AT2020xnd share all key observational properties: a fast optical
rise, sustained high photospheric temperature, absence of a second peak
attributable to ejection of a radioactively heated stellar envelope,
extremely luminous radio, millimetre, and X-ray emission, and a
dwarf-galaxy host. This supports the argument that AT2018cow-like events
represent a distinct phenomenon from slower-evolving radio-quiet
supernovae, likely requiring a different progenitor or a different
central engine. The sample properties of the four known members of this
class to date disfavour tidal disruption models but are consistent with
the alternative model of an accretion powered jet following the direct
collapse of a massive star to a black hole. Contextual filtering of
alert streams combined with rapid photometric verification using
multiband imaging provides an efficient way to identify future members
of this class, even at high redshift.
Original language | English |
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Article number | 5138–5147 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 508 |
ISSN | 0035-8711 |
DOIs | |
Publication status | Published - 2021 |
Keywords
- Supernovae: individual: AT2020xnd
- Transients: supernovae