Unprecedented X-Ray Emission from the Fast Blue Optical Transient AT2022tsd
Abstract
We present the X-ray monitoring campaign of AT2022tsd in the time range δ t rest = 23-116 days rest-frame since discovery. With an initial 0.3-10 keV X-ray luminosity of L x ≈ 1044 erg s-1 at δ t rest ≈ 23 days, AT2022tsd is the most luminous FBOT to date and rivals 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 ${\rm{\Gamma }}={1.89}_{-0.08}^{+0.09}$ and marginal evidence at the 3σ confidence level for intrinsic absorption NHint ≈ 4 × 1019 cm-2. The X-ray light-curve 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.
- Publication:
-
Research Notes of the American Astronomical Society
- Pub Date:
- June 2023
- DOI:
- 10.3847/2515-5172/acdde1
- arXiv:
- arXiv:2306.01114
- Bibcode:
- 2023RNAAS...7..126M
- Keywords:
-
- Supernovae;
- X-ray transient sources;
- Transient sources;
- High energy astrophysics;
- 1668;
- 1852;
- 1851;
- 739;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 5 pages, 1 figure, 1 table. Submitted to RNAAS