Unprecedented X-ray Emission from the Fast Blue Optical Transient AT2022tsd

2023/06/01 by Matthews, D. J., Margutti, R., Metzger, B. D. +8 · 4 citations
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE)

paper · doi:10.48550/arxiv.2306.01114

Abstract

We present the X-ray monitoring campaign of AT2022tsd in the time range δt_rest = 23 - 116 d rest-frame since discovery. With an initial 0.3-10 keV X-ray luminosity of L_x ≈ 10⁴⁴ erg s^-1 at δt_rest≈ 23 d, AT2022tsd is the most luminous FBOT to date and rivals even the most luminous GRBs. We find no statistical evidence for spectral evolution. The average X-ray spectrum is well described by an absorbed simple power-law spectral model with best-fitting photon index Γ= 1.89 ^+0.09_-0.08 and marginal evidence at the 3σ confidence level for intrinsic absorption NH_int≈ 4×10¹⁹ cm^-2. The X-ray light-curve behavior can be either interpreted as a power-law decay L_x∝ t^α with α≈ -2 and superimposed X-ray variability, or as a broken power-law with a steeper post-break decay as observed in other FBOTs such as AT2018cow. We briefly compare these results to accretion models of TDEs and GRB afterglow models.

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