SN 2024ggi: detection of X-ray emission by EP-FXT
ATel #16588; J. Zhang, C. K. Li (IHEP, CAS), H. Q. Cheng, Q. Y. Wu (NAOC, CAS), S. M. Jia , Y. Chen, W. W. Cui, H. Feng, J. Guan, D. W. Han, W. Li, C. Z. Liu, F. J. Lu, L. M. Song, J. Wang, J. J. Xu, S. N. Zhang, H. S. Zhao, X. F. Zhao (IHEP, CAS), C. C. Jin, Z. X. Ling, H. Y. Liu, M. J. Liu, Y. Liu, D. Y. Li, H. Sun, W. Yuan, C. Zhang, W. D. Zhang (NAOC, CAS), R. Z. Li (YNAO, CAS), Y. Wang, H. Zhou (PMO, CAS), K. Nandra, A. Rau, P. Friedrich, N. Meidinger, V. Burwitz (MPE), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (UoL) and B. Cordier (CEA), X. F. Wang (THU), W. X. Li (NAOC, CAS) on behalf of the Einstein Probe team
on 16 Apr 2024; 09:52 UT
Credential Certification: Yuan Liu (liuyuan@bao.ac.cn)
Subjects: X-ray, Supernovae
Following the discovery of the optical transient ATLAS24fsk (SN 2024ggi) in NGC 3621 (Srivastav et al., AstroNote 2024-100; Killestein et al., AstroNote 2024-101; Chen et al., AstroNote 2024-102), we have performed two X-ray observations of SN 2024ggi with the Follow-up X-ray Telescope (FXT) on board Einstein Probe (EP) before 2024-04-15. The observation information and detection results are listed as below:
Obs. No. | Start Time | Exp.(ks) | Flux@0.5-2 keV (erg/s/cm2) | Flux@2-10 keV (erg/s/cm2) | SNR
1 | 2024-04-11T20:22:01 | 17.8 | 0.9e-13 | 2.7e-13 | <5
2 | 2024-04-13T20:32:01 | 8.5 | 0.4(-/0.1+0.2)e-12 | 1.0(-0.4/+0.5)e-12 | >5
The flux is obtained by assuming an absorbed power-law spectrum with N_H=3E23cm^-2 and photon index of 1.4 inferred from the NuSTAR observation (ATEL #16587). In the first observation, EP did not detect X-ray emission associated with SN 2025ggi and the upper limit is given above.
Please note that EP-FXT is currently undergoing in-flight calibration. The derived source parameters may be subject to larger uncertainties, so please use them with caution. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE, and CNES, aimed at enhancing our understanding of transient phenomena across the electromagnetic spectrum.
