AstroNote 2025-316

We observed the field of the tidal disruption event (TDE) 2025aarm (Faris et al., AstroNote 2025-311; also see radio constraints in Sfaradi et al., AstroNote 2025-313 and Christy et al, AstroNote 2025-315) with the ACIS-S instrument on the Chandra Telescope as part of a DDT program (PI Somalwar, OBS ID 31982, Proposal 26629071). We observed for 25ks beginning on Nov 5 2025 22:55 UTC, about 40 days after optical discovery.

We reduced the observations following standard procedures. A source was detected at a position consistent with the optical transient. The source was detected at a flux of 3.91e-4 c/s (90% confidence [0.2-6]e-3 c/s). The spectral shape is poorly constrained, but a power-law fit prefers a photon-index of 2.2 (1.6-6.2 90% confidence). Assuming a photon index of 2.2, the Galactic hydrogen density in the direction of TDE 2025aarm of 4e20 cm^(-2) (HI4PI Collaboration, A&A, 594, A116), and a luminosity distance of 61.5 Mpc, the unabsorbed model flux is 5.9e-15 erg/cm^2/s (90% confidence interval [3-10]e-15 erg/cm2/s) in the 0.5-7.0 keV band (observed), or 2.5e39 erg/s.

We thank the Chandra PI Pat Slane and the entire Chandra team for enabling these rapid observations.