Einstein Probe detection of the onset of a new X-ray outburst of MAXI J1816-195
ATel #17734; H. N. Yang, X. Mao (NAO, CAS), Q. C. Liu (THU), H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team
on 1 Apr 2026; 09:19 UT
Credential Certification: Yuan Liu (liuyuan@bao.ac.cn)
Subjects: X-ray, Neutron Star, Pulsar
We report the detection of a new outburst from MAXI J1816-195 with the Wide-field X-ray Telescope (WXT) onboard the Einstein Probe (EP). The source was discovered in June 2022 (Negoro et al., 2022), and has exhibited multiple outbursts since then. Most recently, the source underwent an outburst in 2025 (ATel #17339). EP-WXT detected an onset of a new outburst on 2026 March 28, with a flux of about 2.2e-11 erg cm-2 s-1 in 0.5-4 keV. The source was not detected in the observation on March 26, with an exposure time of 3 ks, corresponding to a flux upper limit of 9e-12 erg cm-2 s-1. The latest WXT spectrum can be fitted with an absorbed power-law model, with a frozen absorption column density of 2.36e22 according to previous study and a photon index of 1.3 (+0.9/-1.1). The unabsorbed flux in 0.5-4 keV is 3.8 (+1.7/-1.4) e-10 erg cm-2 s-1. FXT follow-up observations have been arranged.
Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).
