AT2021lwx
AT 2021lwx
Astronomical Events
AT 2021lwx (also known as ZTF20abrbeie or "Scary Barbie"[2]) is the most energetic non-quasar optical transient astronomical event ever observed, with a peak luminosity of 7 × 1045 erg per second (erg s−1) and a total radiated energy of more than 1.5 × 1053 erg over three years.[1] Only GRB 221009A was more energetic, while also being far brighter. It was first identified in imagery obtained on 13 April 2021 by the Zwicky Transient Facility (ZTF) astronomical survey[3] and is believed to be due to the accretion of matter into a super massive black hole (SMBH) heavier than one hundred million solar masses (M☉).[2][1][4] It has a redshift of z = 0.9945,[1] which would place it at a distance of about eight billion light-years from earth,[4] and is located in the constellation Vulpecula.[5] No host galaxy has been detected.[2][1]
Forced photometry of earlier ZTF imagery showed AT 2021lwx had already begun brightening by 16 June 2020, as ZTF20abrbeie. It was also detected independently in data from the Asteroid Terrestrial-impact Last Alert System (ATLAS) as ATLAS20bkdj, and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) as PS22iin. At the Neil Gehrels Swift Observatory, X-ray observations were made with the X-ray Telescope and ultraviolet, with the Ultraviolet-Optical Telescope (UVOT).[2][1]
Subrayan et al. originally interpreted it to be a tidal disruption event between an SMBH (~108 M☉) and a massive star (~14 M☉).[2] Wiseman et al. disfavor this interpretation, and instead believe the most likely scenario is "the sudden accretion of a large amount of gas, potentially a giant molecular cloud"[1] (~1,000 M☉),[6] onto an SMBH (>108 M☉).[1][7]
The inferred mass of the SMBH, based on the light to mass ratio, is about 1 hundred million - 1 billion solar masses, given the observed brightness. However, the theoretical limit for an accreting super massive black hole is 1 hundred million solar masses. Given the best understood model of accreting SMBH's, this even may be the most massive SMBH to possibly accrete matter.[8] [citation needed]