XRISM/Xtend Transient Search (XTS) detected an X-ray flare from a YSO

Abstract

XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1712-2310 on 2025-04-05 TT. The source position is determined to be (R.A., Dec.) = (258.042, -23.162), with a systematic error of ∼ 40 arcsec. A plausible counterpart is a YSO CD-23 13197, whose distance is 115 pc. CD-23 13197 is located ∼20 arcsec apart from the position of XRISM J1712-2310. The flare started at 2025-04-05 at ∼23:50 TT. The flare reached its peak on 2025-04-06 at ∼ 01:10. The flare was still ongoing at the end of the XRISM observation, but the e-folding time is estimated to be ∼ 20 ks. The peak flux is estimated as 1 × 10⁻¹² erg s⁻¹ cm⁻² (0.4 – 10.0 keV). Corresponding luminosity is 2 × D₁₂₀ₚ꜀ × 10³⁰ erg s⁻¹ by assuming the distance to XRISM J1712-2310 of D₁₂₀ₚ꜀. We derived the above systematic error for the flux by comparing our derived values for the sources detected with XTS in several observations with those for the corresponding X-ray counterparts. We estimated the systematic error for the source position from the separations between the detected sources with the corresponding counterparts in the same field of view.